Form 10-Q - Quarterly report [Sections 13 or 15(d)]

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 10-Q

(Mark One)


☒			QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2024


☐			TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission File Number: 001-39593

Shattuck Labs, Inc.

(Exact name of registrant as specified in its charter)


Delaware						81-2575858
(State or other jurisdiction of incorporation or organization)						(I.R.S. Employer Identification Number)

500 W. 5th Street, Suite 1200

Austin, TX 78701

(512) 900-4690


(Address of principal executive offices including zip code)

Former name, former address and former fiscal year, if changed since last report: N/A

Securities registered pursuant to Section 12(b) of the Exchange Act:


Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, par value $0.0001 per share	STTK	The Nasdaq Global Select Market

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.


Large accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☒
		Emerging growth company	☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of November 1, 2024, the registrant had 47,739,708 shares of common stock, $0.0001 par value per share, outstanding.

SHATTUCK LABS, INC.

TABLE OF CONTENTS


		Page
PART I	FINANCIAL INFORMATION	1
Item 1.	Condensed Financial Statements (Unaudited)	1
	Condensed Balance Sheets as of September 30, 2024 and December 31, 2023	1
	Condensed Statements of Operations and Comprehensive Loss for the Three and Nine Months Ended September 30, 2024 and 2023	2
	Condensed Statements of Changes in Stockholders’ Equity for the Three and Nine Months Ended September 30, 2024 and 2023	3
	Condensed Statements of Cash Flows for the Nine Months Ended September 30, 2024 and 2023	4
	Notes to the Unaudited Interim Condensed Financial Statements	5
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	16
Item 3.	Quantitative and Qualitative Disclosures About Market Risk	24
Item 4.	Controls and Procedures	24
PART II	OTHER INFORMATION	25
Item 1.	Legal Proceedings	25
Item 1A.	Risk Factors	25
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	25
Item 3.	Defaults Upon Senior Securities	25
Item 4.	Mine Safety Disclosures	25
Item 5.	Other Information	25
Item 6.	Exhibits	26

	Signatures	27

CAUTIONARY NOTE ABOUT FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q contains “forward-looking statements” within the meaning of the federal securities laws, which statements are subject to substantial risks and uncertainties and are based on estimates and assumptions. All statements, other than statements of historical facts, including statements concerning our plans, objectives, goals, strategies, future events, future revenues or performance, financing needs, plans or intentions relating to products and markets, and business trends and other information referred to under the sections entitled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “might,” “will,” “objective,” “intend,” “should,” “could,” “can,” “would,” “expect,” “believe,” “design,” “estimate,” “predict,” “potential,” “plan,” "develop" or the negative of these terms, and similar expressions intended to identify forward-looking statements. Forward-looking statements are not historical facts and reflect our current views with respect to future events. Given the significant uncertainties, you should not place undue reliance on these forward-looking statements.

There are a number of risks, uncertainties and other factors that could cause our actual results to differ materially from the forward-looking statements expressed or implied in this Quarterly Report on Form 10-Q. Such risks, uncertainties and other factors include, among others, the following:

•the timing of the initiation, progress, and expected results of our nonclinical studies, our clinical trials, and our research and development programs;

•our ability to enroll patients in our clinical trials;

•the costs related to our nonclinical studies, our clinical trials and our research and development programs, and the impact of inflationary pressures on such costs;

•our ability to retain the continued service of our key executives and to identify, hire, and retain additional qualified professionals;

•our ability to advance product candidates into, and successfully complete, nonclinical studies and clinical trials;

•the timing or likelihood of regulatory filings and approvals;

•the commercialization of our product candidates, if approved;

•our ability and the potential to successfully manufacture and supply our product candidates for clinical trials and for commercial use, if approved;

•the pricing, coverage, and reimbursement of our product candidates, if approved;

•the implementation of our business model, strategic plans for our business, and product candidates;

•the scope of protection we are able to establish and maintain for intellectual property rights covering our product candidates, and the defense of such intellectual property rights;

•our potential need to obtain additional licenses of third-party technology that may not be available to us or are available only on commercially unreasonable terms, and which may cause us to operate our business in a more costly or otherwise adverse manner that was not anticipated;

•our ability to enter into strategic arrangements and/or collaborations and to realize the potential benefits of such arrangements;

•our ability to contract with third-party suppliers and manufacturers and their ability to perform adequately;

•our estimates regarding the market opportunity for our product candidates, if approved;

•our estimates regarding expenses, capital requirements, and needs for additional financing and our ability to obtain additional capital;

•our financial performance; and

•developments relating to our competitors and our industry, including competing product candidates and therapies.

There may be other factors that may cause our actual results to differ materially from the forward-looking statements expressed or implied in this Quarterly Report on Form 10-Q, including factors disclosed in “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” You should evaluate all forward-looking statements made in this Quarterly Report on Form 10-Q in the context of these risks and uncertainties.

We caution you that the risks, uncertainties, and other factors referred to above and elsewhere in this Quarterly Report on Form 10-Q may not contain all of the risks, uncertainties and other factors that may affect our future results and operations. Moreover, new risks will emerge from time to time. It is not possible for our management to predict all risks. In addition, we cannot assure you that we will realize the results, benefits or developments that we expect or anticipate or, even if substantially realized, that they will result in the consequences or affect us or our business in the way expected.

Any forward-looking statements contained in this Quarterly Report on Form 10-Q speak only as of the date hereof and not of any future date, and we expressly disclaim any intent to update any forward-looking statements, whether as a result of new information, future events or otherwise.

PART I - FINANCIAL INFORMATION

Item 1. Condensed Financial Statements

SHATTUCK LABS, INC.

CONDENSED BALANCE SHEETS

(In thousands, except share and per share amounts)


	September 30, 2024		December 31, 2023
	(unaudited)
Assets
Current assets:
Cash and cash equivalents	$	43,829	$	125,626
Investments	46,229		4,999
Prepaid expenses and other current assets	8,682		12,595
Total current assets	98,740		143,220
Property and equipment, net	10,827		13,804
Other assets	2,153		2,540
Total assets	$	111,720	$	159,564

Liabilities and Stockholders’ Equity
Current liabilities:
Accounts payable	$	2,927	$	1,587
Accrued expenses and other current liabilities	9,474		9,866
Total current liabilities	12,401		11,453
Non-current operating lease liabilities	2,742		3,406
Total liabilities	15,143		14,859
Commitments and contingencies (Note 5)
Stockholders’ equity:
Common stock, $0.0001 par value: 300,000,000 shares authorized; 47,739,708 shares issued and outstanding at September 30, 2024 and 47,260,108 shares issued and outstanding at December 31, 2023	5		5
Additional paid-in capital	459,561		451,006
Accumulated other comprehensive (loss) income	52		4
Accumulated deficit	(363,041)		(306,310)
Total stockholders’ equity	96,577		144,705
Total liabilities and stockholders’ equity	$	111,720	$	159,564

See accompanying notes to unaudited interim condensed financial statements

SHATTUCK LABS, INC.

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

(Unaudited)

(In thousands, except share and per share amounts)


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Collaboration revenue	$	2,997	$	686	$	5,721	$	943
Operating expenses:
Research and development	16,313		24,211		51,816		59,083
General and administrative	4,604		5,073		14,831		14,866
Expense from operations	20,917		29,284		66,647		73,949
Loss from operations	(17,920)		(28,598)		(60,926)		(73,006)
Other income	1,245		1,057		4,195		3,395
Net loss	$	(16,675)	$	(27,541)	$	(56,731)	$	(69,611)
Unrealized gain on investments	57		81		48		884
Comprehensive loss	$	(16,618)	$	(27,460)	$	(56,683)	$	(68,727)

Net loss per share – basic and diluted	$	(0.33)	$	(0.65)	$	(1.12)	$	(1.64)
Weighted-average shares outstanding – basic and diluted	50,833,538		42,477,642		50,730,767		42,461,644

See accompanying notes to unaudited interim condensed financial statements

SHATTUCK LABS, INC.

CONDENSED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY

(Unaudited)

(In thousands, except share amounts)


	Nine months ended September 30, 2024
	Common Stock			Additional Paid-In Capital		Accumulated Other Comprehensive (Loss) Income		Accumulated Deficit		Total Stockholders’ Equity
	Shares	Amount
Balance at December 31, 2023	47,260,108	$	5	$	451,006	$	4	$	(306,310)	$	144,705
Exercise of stock options and purchases pursuant to employee stock purchase plan	145,841	—		609		—		—		609
Issuance of common stock upon settlement of restricted stock units	156,803	—		—		—		—		—
Shares withheld related to net share settlement	(43,533)	—		(437)		—		—		(437)
Stock-based compensation expense	—	—		2,475		—		—		2,475
Proceeds from sale of common stock	—	—		(17)		—		—		(17)
Unrealized loss on investments	—	—		—		(18)		—		(18)
Net loss	—	—		—		—		(18,504)		(18,504)
Balance at March 31, 2024	47,519,219	$	5	$	453,636	$	(14)	$	(324,814)	$	128,813
Exercise of stock options	205,042	—		691		—		—		691
Issuance of common stock upon settlement of restricted stock units	3,975	—		—		—		—		—
Shares withheld related to net share settlement	(967)	—		(10)		—		—		(10)
Stock-based compensation expense	—	—		2,665		—		—		2,665
Unrealized gain on investments	—	—		—		9		—		9
Net loss	—	—		—		—		(21,552)		(21,552)
Balance at June 30, 2024	47,727,269	$	5	$	456,982	$	(5)	$	(346,366)	$	110,616
Exercise of stock options and purchases pursuant to employee stock purchase plan	10,122	—		27		—		—		27
Issuance of common stock upon settlement of restricted stock units	3,375	—		—		—		—		—
Shares withheld related to net share settlement	(1,058)	—		(4)		—		—		(4)
Stock-based compensation expense	—	—		2,556		—		—		2,556
Proceeds from sale of common stock	—	—		—		—		—		—
Unrealized loss on investments	—	—		—		57		—		57
Net loss	—	—		—		—		(16,675)		(16,675)
Balance at September 30, 2024	47,739,708	$	5	$	459,561	$	52	$	(363,041)	$	96,577

See accompanying notes to unaudited interim condensed financial statements

SHATTUCK LABS, INC.

CONDENSED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY

(Unaudited)

(In thousands, except share amounts)


	Nine Months Ended September 30, 2023
	Common Stock			Additional Paid-In Capital		Accumulated Other Comprehensive (Loss) Income		Accumulated Deficit		Total Stockholders’ Equity
	Shares	Amount
Balance at December 31, 2022	42,390,586	$	5	$	396,041	$	(877)	$	(219,012)	$	176,157
Exercise of stock options and purchases pursuant to employee stock purchase plan	11,888	—		39		—		—		39
Issuance of common stock upon settlement of restricted stock units	73,937	—		—		—		—		—
Shares withheld related to net share settlement	(16,153)	—		(39)		—		—		(39)
Stock-based compensation expense	—	—		1,683		—		—		1,683
Unrealized gain on investments	—	—		—		538		—		538
Net loss	—	—		—		—		(20,724)		(20,724)
Balance at March 31, 2023	42,460,258	$	5	$	397,724	$	(339)	$	(239,736)	$	157,654
Exercise of stock options	11,077	—		33		—		—		33
Stock-based compensation expense	—	—		1,852		—		—		1,852
Unrealized gain on investments	—	—		—		265		—		265
Net loss	—	—		—		—		(21,346)		(21,346)
Balance at June 30, 2023	42,471,335	$	5	$	399,609	$	(74)	$	(261,082)	$	138,458
Exercise of stock options and purchases pursuant to employee stock purchase plan	11,849	—		21		—		—		21
Issuance of common stock upon settlement of restricted stock units	3,375	—		—		—		—		—
Shares withheld related to net share settlement	(1,074)	—		—		—		—		—
Stock-based compensation expense	—	—		1,764		—		—		1,764
Unrealized gain on investments	—	—		—		81		—		81
Net loss	—	—		—		—		(27,541)		(27,541)
Balance at September 30, 2023	42,485,485	$	5	$	401,394	$	7	$	(288,623)	$	112,783

See accompanying notes to unaudited interim condensed financial statements

SHATTUCK LABS, INC.

CONDENSED STATEMENTS OF CASH FLOWS

(Unaudited)

(In thousands)


	Nine Months Ended September 30,
	2024		2023
Cash flows from operating activities:
Net loss	$	(56,731)	$	(69,611)
Adjustments to reconcile net loss to net cash used in operations:
Stock-based compensation	7,696		5,299
Depreciation	2,889		3,061
Impairment loss	147		204
Non-cash operating lease expense	315		267
Net amortization of investments	(1,730)		(1,055)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	3,913		11,890
Other assets	72		129
Accounts payable	1,340		(5,154)
Accrued expenses and other current liabilities	(392)		(6,252)
Non-current operating lease liabilities	(664)		(587)
Net cash used in operating activities	(43,145)		(61,809)
Cash flows from investing activities:
Purchase of property and equipment	(59)		(390)
Maturities of investments	54,100		130,199
Purchases of investments	(93,552)		(74,801)
Net cash (used in) provided by investing activities	(39,511)		55,008
Cash flows from financing activities:
Proceeds from the exercises of stock options and purchases pursuant to employee stock purchase plan	1,327		93
Taxes paid related to net share settlement of equity awards	(451)		(39)
Proceeds from sale of common stock	(17)		—
Net cash provided by financing activities	859		54
Net decrease in cash and cash equivalents	(81,797)		(6,747)
Cash and cash equivalents, beginning of period	125,626		47,379
Cash and cash equivalents, end of period	$	43,829	$	40,632
Supplemental disclosures of non-cash financial activities:
Deferred revenue billed but not received	$	—	$	500

See accompanying notes to unaudited interim condensed financial statements

SHATTUCK LABS, INC.

NOTES TO THE UNAUDITED INTERIM CONDENSED FINANCIAL STATEMENTS

1. Organization and Description of Business

Shattuck Labs, Inc. (the “Company”) was incorporated in 2016 in the State of Delaware and is a biotechnology company specializing in the development of potential treatments for inflammatory and immune-mediated diseases, cancer, and other therapeutic areas. Shattuck is developing a potentially first-in-class antibody for the treatment of inflammatory bowel disease ("IBD") and other inflammatory and immune-mediated diseases. Shattuck’s expertise in protein engineering and the development of novel tumor necrosis factor ("TNF") receptor agonist and antagonist therapeutics come together in its lead program, SL-325, which it believes could be a first-in-class death receptor 3 ("DR3") antagonist antibody designed to achieve a more complete blockade of the clinically validated TL1A/DR3 pathway.

Liquidity

The Company has incurred losses and negative cash flows from operations since inception and has an accumulated deficit of $363.0 million as of September 30, 2024. The Company anticipates incurring additional losses and negative cash flows from operations until such time, if ever, that it can generate significant sales of its product candidates currently in development, and is highly dependent on its ability to find additional sources of funding in the form of licensing of its technology, collaboration agreements and/or public and private debt and equity financings. Adequate additional funding may not be available to the Company on acceptable terms, or at all. The failure to raise funds as and when needed could have a negative impact on the Company’s financial condition and ability to pursue its clinical operations, research and development and commercialization of its product candidates. Management believes that the Company’s cash, cash equivalents and investments of $90.1 million as of September 30, 2024 are sufficient to fund projected operations of the Company for at least the next twelve months.

Global Economic Considerations

The global macroeconomic environment is uncertain and could be negatively affected by, among other things, increased U.S. trade tariffs and trade disputes with other countries, instability in the global capital and credit markets, supply chain weaknesses, financial institution instability, and instability in the geopolitical environment. Such challenges have caused, and may continue to cause, recession fears, high interest rates, foreign exchange volatility and inflationary pressures. At this time, the Company is unable to quantify the potential effects of this economic instability on its future operations.

2. Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited interim condensed financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”).

Unaudited Interim Condensed Financial Statements

In the opinion of management, the accompanying interim financial statements include all normal and recurring adjustments (which consist primarily of accruals, estimates and assumptions that impact the financial statements) considered necessary to present fairly the Company’s financial position, its results of operations, statements of changes in stockholders’ equity and cash flows for the interim periods presented. Operating results for interim periods presented are not necessarily indicative of the results that may be expected for the year ending December 31, 2024. The interim financial statements presented herein do not contain all required disclosures under GAAP for annual financial statements. The accompanying unaudited interim condensed financial statements should be read in conjunction with the annual audited financial statements and related notes in the Company's Annual Report on Form 10-K for the year ended December 31, 2023.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, revenue recognition,

the accrual of research and development expenses, and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates, if any, are recorded in the period in which they become known and actual results could differ from management’s estimates.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business as one segment.

Fair Value of Financial Instruments

Fair value is defined as the price that would be received upon the sale of an asset or paid upon the transfer of a liability in an orderly transaction between market participants at the measurement date and in the principal or most advantageous market for that asset or liability. Fair value measurements are classified and disclosed in one of the following categories:

•Level 1: Observable inputs such as quoted prices in active markets for identical assets the reporting entity has the ability to access as of the measurement date;

•Level 2: Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and

•Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.

Fair value measurements are classified based on the lowest level of input that is significant to the measurement. The Company’s assessment of the significance of a particular input to the fair value measurement requires judgment, which may affect the valuation of the assets and liabilities and their placement within the fair value hierarchy levels. The determination of the fair values takes into account the market for its financial assets and liabilities, the associated credit risk and other factors as required. The Company considers active markets as those in which transactions for the assets or liabilities occur with sufficient frequency and volume to provide pricing information on an ongoing basis.

Management believes that the carrying amounts of the Company’s financial instruments, including investments and accounts payable, approximate fair value due to the short-term nature of those instruments.

Concentration of Risk

Financial instruments that potentially subject the Company to concentrations of credit risk primarily consist of cash, cash equivalents and investments. The Company maintains its cash and cash equivalents at two accredited financial institutions in amounts that exceed federally-insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company invests in only U.S. Treasury securities that management believes protects the Company from risk of default and impairment of value.

All of the Company’s revenue in 2024 has been derived from collaborations with Ono Pharmaceutical Co., Ltd (“Ono”) and ImmunoGen, Inc. ("ImmunoGen"), and revenue in 2023 was derived from a collaboration agreement with ImmunoGen (the “ImmunoGen Agreement”). In February 2024, ImmunoGen was acquired by AbbVie, Inc.

The Company is highly dependent on a limited number of contract development and manufacturing organizations (“CDMOs”) to supply drug products for its research and development activities of its programs, including clinical trials and non-clinical studies. These programs could be adversely affected by a significant interruption in the supply of such drug products.

The Company is highly dependent on a limited number of contract research organizations (“CROs”) and third-party service providers to manage and support its clinical trials. These programs could be adversely affected by a significant disruption in services provided by these CROs and third parties.

Cash and Cash Equivalents

The Company considers all demand deposits with financial institutions and all highly liquid investments with original maturities of 90 days or less at the date of purchase to be cash and cash equivalents. Cash and cash equivalents consisted of $3.1 million held in operating accounts, $32.4 million held in money market funds and $8.4 million in U.S. Government Securities as of September 30, 2024, and $4.8 million held in operating accounts, $81.1 million held in money market funds and $39.7 million in U.S. Government Securities as of December 31, 2023.

Investments

The Company’s investments consist of highly-rated U.S. Treasury securities and have been classified as available-for-sale and are carried at estimated fair value as determined based upon quoted market prices. Management determines the appropriate classification of its investment securities at the time of purchase. The Company may hold securities with stated maturities greater than one year. All available-for-sale securities are considered available to support current operations and are classified as current assets. Credit impairments for available-for-sale securities are recorded through an allowance rather than a direct write-down of the security and are recorded through a charge to the statements of operations. Unrealized gains or losses not related to credit impairments are recorded in accumulated other comprehensive income (loss), a component of stockholders’ equity, until realized. The Company reviews available-for-sale debt securities for impairments related to credit losses and other factors each quarter. There were no impairments of investments for the three and nine months ended September 30, 2024 and 2023.

Impairment of Long-Lived Assets

Long-lived assets are reviewed for indications of possible impairment whenever events or changes in circumstance indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amounts to the future undiscounted cash flows attributable to these assets. An impairment loss is recognized to the extent an asset group is not recoverable and the carrying amount exceeds the projected discounted future cash flows arising from these assets. There were $0.1 million and $0.2 million of impairments of long-lived assets for the three and nine months ended September 30, 2024, respectively, and there were $0.2 million of impairments of long-lived assets for both the three and nine months ended September 30, 2023.

Leases

The Company determines if an arrangement is a lease at inception. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The classification of the Company’s leases as operating or finance leases, along with the initial measurement and recognition of the associated ROU assets and lease liabilities, are performed at the lease commencement date. The measurement of lease liabilities is based on the present value of future lease payments over the lease term. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of future lease payments. The ROU asset is based on the measurement of the lease liability and also includes any lease payments made prior to or on lease commencement and excludes lease incentives and initial direct costs incurred, as applicable. The lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise any such options. Rent expense for the Company’s operating leases is recognized on a straight-line basis over the lease term. The Company has elected to not apply the recognition requirement of Accounting Standards Codification (“ASC”) 842, Leases of the Financial Accounting Standards Board (“FASB”) to leases with a term of 12 months or less for all classes of assets.

Commitments and Contingencies

The Company follows ASC 450-20, Contingencies of the FASB to report accounting for contingencies. Certain conditions may exist as of the date the condensed financial statements are issued, which may result in a loss to the Company but which will only be resolved when one or more future events occur or fail to occur. The Company assesses such contingent liabilities, and such assessment inherently involves an exercise of judgment. In assessing loss contingencies related to legal proceedings that are pending against the Company or unasserted claims

that may result in such proceedings, the Company evaluates the perceived merits of any legal proceedings or unasserted claims as well as the perceived merits of the amount of relief sought or expected to be sought therein.

If the assessment of a contingency indicates that it is probable that a material loss has been incurred and the amount of the liability can be estimated, then the estimated liability would be accrued in the Company’s condensed financial statements. If the assessment indicates that a potential material loss contingency is not probable but is reasonably possible, or is probable but cannot be estimated, then the nature of the contingent liability, and an estimate of the range of possible losses, if determinable and material, would be disclosed.

Loss contingencies considered remote are generally not disclosed unless they involve guarantees, in which case the guarantees would be disclosed.

Revenue Recognition

Collaboration revenue is recognized in accordance with ASC 606, Revenue from Contracts with Customers (“ASC 606”). Arrangements with collaborators may include licenses to intellectual property, research and development services, manufacturing services for clinical and commercial supply and participation on joint steering committees. The Company evaluates the promised goods or services in the contract to determine which promises, or group of promises, represent performance obligations. In contemplation of whether a promised good or service meets the criteria required of a performance obligation, the Company considers the stage of development of the underlying intellectual property, the capabilities and expertise of the customer relative to the underlying intellectual property and whether the promised goods or services are integral to or dependent on other promises in the contract. When accounting for an arrangement that contains multiple performance obligations, the Company must develop judgmental assumptions, which may include market conditions, reimbursement rates for personnel costs, development timelines and probabilities of regulatory success to determine the stand-alone selling price for each performance obligation identified in the contract.

Upon the amendment of an existing agreement, the Company evaluates whether the amendment represents a modification to an existing contract that would be recorded through a cumulative catch-up to revenue, or a separate contract. If it is determined that it is a separate contract, the Company will evaluate the necessary revenue recognition through the five-step process described below.

When the Company concludes that a contract should be accounted for as a combined performance obligation and recognized over time, the Company must then determine the period over which revenue should be recognized and the method by which to measure revenue. The Company generally recognizes revenue using a cost-based input method.

The Company recognizes collaboration revenue in an amount that reflects the consideration that the Company expects to receive in exchange for those goods or services when its customer or collaborator obtains control of promised goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the following five steps are performed:

i.identify the contract(s) with a customer;

ii.identify the performance obligations in the contract;

iii.determine the transaction price;

iv.allocate the transaction price to the performance obligations within the contract; and

v.recognize revenue when (or as) the entity satisfies a performance obligation.

The Company only applies the five-step model to contracts when it determines that it is probable it will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer.

At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within the contract to determine whether each promised good or service is a performance obligation. The promised goods or services in the Company’s arrangements may consist of a license of, or options to license, the Company’s intellectual property and research, development and manufacturing services. The Company may provide options to additional items in such arrangements, which are accounted for as separate contracts when the customer elects to exercise such options, unless the option provides a material right to the

customer. Performance obligations are promises in a contract to transfer a distinct good or service to the customer that (i) the customer can benefit from on its own or together with other readily available resources and (ii) are separately identifiable from other promises in the contract. Goods or services that are not individually distinct performance obligations are combined with other promised goods or services until such combined group of promises meet the requirements of a performance obligation.

The Company determines transaction price based on the amount of consideration the Company expects to receive for transferring the promised goods or services in the contract. Consideration may be fixed, variable or a combination of both. At contract inception for arrangements that include variable consideration, the Company estimates the probability and extent of consideration it expects to receive under the contract utilizing either the most-likely amount method or expected amount method, whichever best estimates the amount expected to be received. The Company then considers any constraints on the variable consideration and includes variable consideration in the transaction price to the extent it is deemed probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved.

The Company then allocates the transaction price to each performance obligation based on the relative standalone selling price and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. For performance obligations that consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition.

The Company records amounts as accounts receivable when the right to consideration is deemed unconditional. When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded as deferred revenue.

Amounts received prior to satisfying the revenue recognition criteria are recognized as deferred revenue in the Company’s accompanying balance sheet. Deferred revenues expected to be recognized as revenue within the 12 months following the balance sheet date are classified as a current liability. Deferred revenues not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as non-current liabilities.

The Company’s collaboration revenue arrangements may include the following:

Up-front License Fees: If a license is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from nonrefundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition.

Milestone Payments: At the inception of an agreement that includes research and development milestone payments, the Company evaluates each milestone to determine when and how much of the milestone to include in the transaction price. The Company first estimates the amount of the milestone payment that the Company could receive using either the expected value or the most-likely amount approach. The Company primarily uses the most-likely amount approach as that approach is generally most predictive for milestone payments with a binary outcome. The Company then considers whether any portion of that estimated amount is subject to the variable consideration constraint (that is, whether it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty). The Company updates the estimate of variable consideration included in the transaction price at each reporting date which includes updating the assessment of the likely amount of consideration and the application of the constraint to reflect current facts and circumstances.

Royalties: For arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company will

recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

To date, the Company has not granted a development and commercialization license nor recognized any revenue related to sales-based royalties or milestone payments based on the level of sales.

Research and Development Services: The Company will record costs associated with development and process optimization activities as research and development expenses in the statements of operations and comprehensive loss consistent with ASC 730, Research and Development. The Company considered the guidance in ASC 808, Collaborative Arrangements ("ASC 808") and will recognize the payments received from these agreements as revenue when the related costs are incurred.

Research and Development Costs

Research and development costs are expensed as incurred, and include salaries, stock-based compensation and other personnel-related costs, equipment and supplies, depreciation, nonclinical studies, clinical trials and manufacturing development activities.

A substantial portion of the Company’s ongoing research and development activities are conducted by third-party service providers, including CROs and CDMOs. The Company accrues for expenses resulting from obligations under agreements with CROs, CDMOs and other outside service providers for which payment flows do not match the periods over which materials or services are provided to the Company. Accruals are recorded based on estimates of services received and efforts expended pursuant to agreements established with CROs, CDMOs and other outside service providers. These estimates are typically based on contracted amounts applied to the proportion of work performed and determined through an evaluation of the progress or stage of completion of the services. In the event advance payments are made to a CRO, CDMO or outside service provider, the payments will be recorded as a prepaid asset, which will be amortized as the contracted services are performed. As actual costs become known, the Company adjusts its accruals and prepaid assets accordingly. Inputs, such as the services performed, the number of patients enrolled or the study duration, may vary from the Company’s estimates, resulting in adjustments to research and development expense in future periods. The Company makes significant judgments and estimates in determining the accrual and/or prepaid balance in each reporting period and changes in these estimates may result in material changes to the Company’s accruals that could materially affect the Company’s results of operations.

Net Loss Per Share

Basic loss per share of common stock is computed by dividing net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during each period. Basic shares outstanding includes the weighted average effect of the Company’s outstanding 3,100,823 pre-funded warrants, the exercise of which requires nominal consideration for the delivery of shares of common stock. Diluted loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as redeemable convertible preferred stock or convertible notes, if any, stock options and unvested shares of restricted stock, which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive.

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding as they would be anti-dilutive:


	As of September 30,
	2024	2023
Stock options	6,419,787	5,357,517
Unvested restricted stock units	1,008,535	655,777
	7,428,322	6,013,294

Other Comprehensive Income (Loss)

Other comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Other comprehensive income (loss) is comprised of the net loss and unrealized gains and losses on investments.

Recently Adopted Accounting Pronouncements

The Company will adopt Update 2023-07 in the period required and while it will require the Company to expand certain disclosures within the notes to its financial statements, the Company does not expect the adoption to have a material impact on the its financial position, operating results or cash flows.

In November 2024, the FASB issued ASU 2024-03, Accounting Standards Update 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses to improve financial reporting by requiring that public business entities disclose additional information about specific expense categories in the notes to financial statements at interim and annual reporting periods. This ASU is effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently evaluating the impact of adopting this ASU to its notes to the consolidated financial statements and processes.

3. Investments

The following table represents the Company’s available-for-sale investments by major security type (amounts in thousands):


	September 30, 2024
	Amortized Cost		Gross Unrealized Gain		Total Fair Value
Investments:
U.S. government securities	$	46,181	$	48	$	46,229
Cash equivalents:
U.S. government securities	8,348		4		8,352
Total level 1 debt securities	$	54,529	$	52	$	54,581


	December 31, 2023
	Amortized Cost		Gross Unrealized Gain		Total Fair Value
Investments:
U.S. government securities	$	4,998	$	1	$	4,999
Cash equivalents:
U.S. government securities	39,657		3		39,660
Total level 1 debt securities	$	44,655	$	4	$	44,659

The Company’s investment instruments and cash and cash equivalents are classified using Level 1 inputs within the fair value hierarchy and are valued using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Debt securities have a weighted-average maturity of 0.17 years as of September 30, 2024.

4. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (amounts in thousands):


	September 30, 2024		December 31, 2023
Research and development contract costs	$	4,868	$	4,235
Compensation and related benefits	1,885		3,794
Customer refund	1,613		—
Operating lease liabilities	873		796
Other	235		1,041
Total accrued expenses and other current liabilities	$	9,474	$	9,866

5. Commitments and Contingencies

Operating Leases

The Company leases certain office space, laboratory facilities, and equipment. These leases require monthly lease payments that may be subject to annual increases throughout the lease term. Certain of these leases also include renewal options at the election of the Company to renew or extend the lease. These optional periods have not been considered in the determination of the ROU assets or lease liabilities associated with these leases as the Company did not consider it reasonably certain it would exercise the options. The Company performed evaluations of its contracts and determined it has operating leases. There have been no material changes in the Company's operating leases as compared to the operating leases disclosed in the Company's Annual Report on Form 10-K for the year ended December 31, 2023.

Kopfkino License Agreement

The Company is party to an Exclusive License Agreement (the “Kopfkino License Agreement”), with Kopfkino IP, LLC (“Kopfkino”). As of October 2024, the Company discontinued clinical development of its SL-172154 product candidate that was subject to the Kopfkino License Agreement. The Company retains the exclusive license, but does not have any plans for clinical development or commercialization of any products that would be subject to the Kopfkino License Agreement and, therefore, the Company does not expect to owe milestone payments or royalties under the agreement.

Litigation

From time to time, the Company may become involved in various legal actions arising in the ordinary course of business. As of September 30, 2024, the Company was not aware of any existing, pending, or threatened legal actions that would have a material impact on the financial position, results of operations, or cash flows of the Company.

Contractual Obligations

Contractual obligations represent future cash commitments and liabilities under agreements with third parties, and exclude contingent liabilities for which the Company cannot reasonably predict future payment. The Company’s contractual obligations result primarily from obligations for various CDMOs and CROs, which include potential payments that may be required under its agreements. The contracts also contain variable costs and milestones that are hard to predict, as they are based on such things as patients enrolled and clinical trial sites. The timing of payments and actual amounts paid under CDMO and CRO agreements may be different depending on the timing of receipt of goods or services or changes to agreed-upon terms or amounts for some obligations. Such agreements are cancellable upon written notice by the Company and, therefore, are not long-term liabilities.

6. Collaboration Agreements

The Company recognizes revenue for collaboration agreements using a cost-based input measure. In applying the cost-based input method of revenue recognition, the Company uses actual costs incurred relative to budgeted costs expected to be incurred, and any upfront payments are deferred accordingly.

Ono Pharmaceutical Co., Ltd

In February 2024, the Company entered into a collaboration and license agreement (the “Ono Agreement”) with Ono, pursuant to which the parties collaborated in the research and preclinical development of certain compounds selected by Ono from the Company’s pipeline of bifunctional fusion proteins directed toward a pair of prespecified targets for potential treatment of autoimmune and inflammatory diseases. On September 30, 2024, the Company and Ono mutually agreed to terminate the Ono Agreement (the "Ono Termination Agreement"). Following the mutual termination, the Company is no longer required to satisfy any remaining performance obligations, and will not receive any future research activity reimbursements or upfront, milestone, or royalty payments from Ono. All options and licenses held by Ono under the Collaboration Agreement were terminated.

The Ono Agreement was a collaborative arrangement under ASC 808 as both companies were active participants that were exposed to significant risks and rewards. However, since the units of account identified under ASC 808 followed a typical vendor/customer relationship, the Company accounted for the transaction under ASC 606.

Under the Ono Agreement, the Company granted Ono an exclusive option (the “Option”) to obtain an exclusive, sublicensable license to further research, develop, manufacture and commercialize products containing the specified bifunctional fusion proteins in any therapeutic area worldwide. The Company determined that the contingent promise to provide the license upon the exercise of the Option should be accounted for as a customer option, and the $2.0 million amount allocated to that option was recognized as revenue upon the termination of the Option pursuant to the termination of the Ono Agreement.

The Company identified a single performance obligation consisting of the preclinical research activities to develop certain bifunctional fusion proteins. The Company recognized revenue for the preclinical research activities as the services were performed using an inputs method. The Company recognized revenue pursuant to the Ono Agreement of $3.0 million and $5.4 million for the three and nine months ended September 30, 2024, respectively, and did not recognize any revenue pursuant to the Ono Agreement in 2023.

In August of 2024 the Company received an additional prepayment of $1.6 million for services to be performed in the fourth quarter of 2024. Pursuant to the Ono Termination Agreement, this prepayment was refunded to Ono in the fourth quarter of 2024.

ImmunoGen

In 2022, the Company entered into the ImmunoGen Agreement, pursuant to which ImmunoGen will reimburse the Company for $2.0 million of the costs the Company incurs in the Phase 1B combination cohort evaluating SL-172154 in combination with mirvetuximab soravtansine in patients with platinum-resistant ovarian cancer. The Company dosed its first patient with mirvetuximab soravtansine in 2023 and completed all of its obligations under the ImmunoGen Agreement in the second quarter of 2024. The Company recognized revenue of $0.0 million and $0.3 million pursuant to the ImmunoGen Agreement for the three and nine months ended September 30, 2024, respectively, and $0.7 million and $0.9 million pursuant to the ImmunoGen Agreement for the three and nine months ended September 30, 2023, respectively.

7. Equity

The Company is authorized to issue up to 300,000,000 shares of common stock and 10,000,000 shares of preferred stock, all with a par value of $0.0001 per share. The holders of the Company’s common stock are entitled to one vote per share on all matters submitted to a vote of stockholders. The Company’s common stock is not entitled to preemptive rights, and is not subject to conversion, redemption or sinking fund provisions. Subject to preferences that may apply to any shares of preferred stock outstanding at the time, the holders of the Company’s common stock will receive ratably any dividends declared by the Company’s board of directors (the “Board”) out of funds legally available. In the event of the Company’s liquidation, dissolution or winding-up, the holders of the

Company’s common stock will be entitled to share ratably in all assets remaining after payment of or provision for any liabilities. As of the periods presented, no common stock dividends had been declared by the Board. As of September 30, 2024, none of the 10,000,000 shares of preferred stock were outstanding, and the Company has no present plans to issue any shares of preferred stock.

In July 2022, the Company entered into a sales agreement (the “Sales Agreement”) with Leerink Partners LLC (the “Sales Agent”), pursuant to which it may offer and sell up to $75.0 million of shares of its common stock from time to time (the “ATM Facility”). The Sales Agent is generally entitled to compensation at a commission equal to 3.0% of the aggregate gross sales price per share sold under the Sales Agreement. As of September 30, 2024, there were no sales pursuant to the ATM Facility.

In December 2023, the Company sold 4,651,163 shares of common stock through an underwritten public offering, and concurrently completed a private placement of 3,100,823 pre-funded warrants. The purchase price per share of common stock was $6.45, and the purchase price per pre-funded warrant was $6.4499, which was the purchase price per share of common stock minus the $0.0001 per share exercise price of such pre-funded warrant. Each pre-funded warrant may be exercised for one share of common stock, is immediately exercisable, does not expire, and is subject to a beneficial ownership limitation of 9.99% on a post-exercise basis. As of September 30, 2024, all 3,100,823 pre-funded warrants remain outstanding.

8. Stock-Based Compensation and Employee Benefit Plans

2020 Equity Incentive Plan

In September 2020, the Company adopted the 2020 Stock Incentive Plan (the “2020 Plan”) which, as of the adoption date, replaced the 2016 Stock Incentive Plan. Under the 2020 Plan, the share reserve automatically increases on January 1st of each year beginning in 2021 and ending with a final increase on January 1, 2030 in an amount equal to 4% of the Company’s outstanding shares of common stock on December 31st of the preceding calendar year. The Board may provide that there will be no increase in the share reserve for any such year or that the increase in the share reserve may be smaller than would otherwise occur. On January 1, 2024, the share reserve automatically increased by 1,890,404 shares. As of September 30, 2024, there were 3,516,051 shares available for future grants. The 2020 Plan permits the granting of options, stock appreciation rights, restricted stock units (“RSUs”), performance stock and performance cash awards. The terms of the agreements under the 2020 Plan are determined by the Board. The Company’s awards generally vest over four years and have a term of 10 years. Periodically, the Company also grants awards that vest based on the Company's stock achieving certain closing share prices for a specified number of consecutive trading days.

2020 Employee Stock Purchase Plan

The 2020 Employee Stock Purchase Plan (the “2020 ESPP”) became effective in October 2020. Eligible employees may purchase shares of common stock under the 2020 ESPP at 85% of the lower of the fair market value of the Company’s common stock as of the first or the last day of each offering period. Employees are limited to contributing 15% of the employee’s eligible compensation and may not purchase more than $25,000 of stock during any calendar year or more than 600 shares during any one purchase period. The 2020 ESPP share reserve automatically increases on January 1st of each calendar year, for ten years, commencing on January 1, 2021, in an amount equal to 1% of the total number of shares of common stock outstanding on December 31st of the preceding calendar year. The Board may act prior to January 1st of a given year to provide that there will be no January 1st increase of the share reserve for such year or that the increase in the share reserve for such year will be a smaller number of shares of common stock than would otherwise occur pursuant to the preceding sentence. On January 1, 2024, the share reserve increased by 472,601 shares of common stock. As of September 30, 2024, there were 1,660,229 shares available for future purchases. There were 9,960 and 11,849 shares issued under the Company’s 2020 ESPP for aggregate proceeds of less than $0.1 million during the three months ended September 30, 2024 and 2023, respectively. During the nine months ended September 30, 2024 and 2023, the Company issued 17,246 and 23,020 shares of common stock for aggregate cash proceeds of $0.1 million and $0.1 million, respectively.

Summary of Stock-Based Compensation Expense

The Company recorded stock-based compensation expense in the following expense categories of its accompanying unaudited interim condensed statements of operations and comprehensive loss (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	1,420	$	921	$	4,131	$	2,681
General and administrative	1,136		843		3,565		2,618
Total stock-based compensation	$	2,556	$	1,764	$	7,696	$	5,299

Stock Options

The following table summarizes option activity under the 2020 Plan for the nine months ended September 30, 2024:


	Options	Weighted Average Exercise Price		Weighted Average Remaining Life (Years)
Balance at December 31, 2023	4,942,164	$	7.21	7.62
Granted	2,038,268	9.24
Exercised	(343,759)	3.75
Forfeited	(216,886)	11.54
Balance at September 30, 2024	6,419,787	$	7.89	7.64
Vested and expected to vest	6,175,278	$	7.87	7.61
Exercisable at the end of the period	3,487,703	$	7.63	6.60

Options granted during the nine months ended September 30, 2024 and 2023 had weighted-average grant-date fair values of $7.29 and $2.50 per share, respectively. As of September 30, 2024, the unrecognized compensation cost for options issued was $17.0 million and will be recognized over an estimated weighted-average amortization period of 2.47 years. The total intrinsic value of options exercised during the nine months ended September 30, 2024 and 2023 was $1.9 million and $0, respectively. The aggregate intrinsic value of options outstanding and exercisable as of September 30, 2024 was $0.8 million.

Restricted Stock Units

The following table summarizes employee RSU activity for the nine months ended September 30, 2024:


	Awards	Weighted Average Grant Date Fair Value
Balance at December 31, 2023	590,403	$	4.80
Granted	638,476	10.09
Released	(164,153)	5.05
Forfeited	(56,191)	6.29
Balance at September 30, 2024	1,008,535	$	8.03

The Company recognized $1.6 million and $0.7 million of stock-based compensation cost related to RSUs for the nine months ended September 30, 2024 and 2023, respectively. As of September 30, 2024, the unrecognized compensation cost for RSUs issued was $5.6 million and will be recognized over an estimated weighted-average amortization period of 2.80 years. The fair values of RSUs are based on the fair value of the Company’s common stock on the date of the grant.

Fair Value of Stock Options and Shares Issued

The Company accounts for stock-based compensation by measuring and recognizing as compensation expense the fair value of all share-based payment awards made to employees, including employee stock options and restricted stock awards. The Company uses the Black-Scholes option pricing model to estimate the fair value of employee stock options that only have service or performance conditions. The Company uses the Monte Carlo pricing model to estimate the fair value of options that have market-based conditions. The inputs to both pricing models require a number of management estimates such as the expected term, volatility, risk-free interest rate and dividend yield. The fair value of stock options was determined using the methods and assumptions discussed below.

•The expected term of employee stock options with service-based vesting is determined using the “simplified” method, whereby the expected life equals the arithmetic average of the vesting term and the original contractual term of the option due to the Company’s lack of sufficient historical data.

•The expected stock price volatility assumption is based on the historical volatilities of the common stock of a peer group of publicly traded companies as well as the historical volatility of the Company’s common stock since the Company began trading subsequent to the Company’s initial public offering (“IPO”) in October 2020 over the period corresponding to the expected life as of the grant date. The historical volatility data was computed using the daily closing prices during the equivalent period of the calculated expected term of the stock-based awards. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of the Company’s stock price becomes available, or until circumstances change, such that the identified entities are no longer comparable companies. In the latter case, other suitable, similar entities whose share prices are publicly available would be utilized in the calculation.

•The risk-free interest rate is based on the interest rate payable on U.S. Treasury securities in effect at the time of grant for a period that is commensurate with the expected term.

•The expected dividend yield is 0% because the Company has not historically paid, and does not expect, for the foreseeable future, to pay dividends on its common stock.

•Prior to the Company’s IPO, the Board periodically estimated the fair value of the Company’s common stock considering, among other things, contemporaneous valuations of its common stock prepared by an unrelated third-party valuation firm. Subsequent to the Company’s IPO, options are issued with a strike price no less than the market price on date of grant.

The grant-date fair value of options calculated using the Black-Scholes option pricing model granted under the Company’s 2020 Plan were estimated using the following weighted-average assumptions:


	Nine Months Ended September 30,
	2024		2023
2020 Plan
Expected term - years	6.02		6.02
Expected volatility	96.1	%	84.6	%
Risk-free interest rate	4.1	%	3.6	%
Expected dividends	—		—

For the nine months ended September 30, 2024, there have been no options granted that require the use of the Monte Carlo option pricing model. For the nine months ended September 30, 2023, the grant-date fair value of

options calculated using the Monte Carlo option pricing model granted under the Company’s 2020 Plan were estimated using the following assumptions.


	Nine Months Ended September 30, 2023
2020 Plan
Expected term - years	4.00
Expected volatility	80.0	%
Risk-free interest rate	3.6	%
Expected dividends	—

The grant-date fair value of shares issued calculated using the Black-Scholes option pricing model under the Company’s 2020 ESPP were estimated using the following weighted-average assumptions:


	Nine Months Ended September 30,
	2024		2023
2020 ESPP
Expected term - years	0.50		0.50
Expected volatility	115.1	%	85.5	%
Risk-free interest rate	5.1	%	4.0	%
Expected dividends	—		—

9. Discontinuation of SL-172154 Clinical Development

On October 1, 2024, the Company approved a restructuring plan to prioritize the development of the Company’s DR3 program. The restructuring plan is intended to optimize the Company’s cost structure by aligning the size and structure of its workforce with the Company’s current goals and strategy. The organizational realignment includes discontinuing the Company’s SL-172154 program in view of overall survival data readouts from its studies in higher-risk myelodysplastic syndromes and acute myeloid leukemia. Approximately 40% of Shattuck’s workforce was impacted by the changes. The Company has substantially completed the reduction in force.

As a result of these changes, the Company expects to incur restructuring charges between $1.5 million and $1.75 million, the majority of which are related to employee severance costs. The Company anticipates recognizing these expenses in the fourth quarter of 2024. Substantially all of the charges are expected to be future cash expenditures. The estimates of costs and expenses that the Company expects to incur in connection with the changes are contingent on various assumptions and actual results may differ materially. The Company may also incur additional costs not currently contemplated due to events related to or resulting from these strategic steps.

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

You should read the following discussion and analysis of our financial condition and results of operations together with our unaudited condensed financial statements and related notes appearing in this Quarterly Report on Form 10-Q, as well as the audited financial statements, notes and Management’s Discussion and Analysis of Financial Condition and Results of Operations included in our Annual Report on Form 10-K for the year ended December 31, 2023. This discussion and other parts of this Quarterly Report on Form 10-Q contain forward-looking statements that involve risks and uncertainties, such as statements of our plans, objectives, expectations and intentions. Our actual results could differ materially from those discussed in these forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed in the “Risk Factors” section of this Quarterly Report on Form 10-Q. You should carefully read the “Cautionary Note About Forward-Looking Statements” of this Quarterly Report on Form 10-Q and the “Risk Factors” section of our Annual Report on Form 10-K for the year ended December 31, 2023 to gain an understanding of the important factors that could cause actual results to differ materially from the results described below.

Overview

We are a biotechnology company specializing in the development of potential treatments for inflammatory and immune-mediated diseases and cancer. We are developing a potentially first-in-class antibody for the treatment of inflammatory bowel disease ("IBD") and other inflammatory and immune-mediated diseases. Our expertise in protein engineering and the development of novel tumor necrosis factor ("TNF") receptor agonist and antagonist therapeutics come together in our lead program, SL-325, which we believe could be a first-in-class death receptor 3 ("DR3") antagonist antibody designed to achieve a more complete blockade of the clinically validated TL1A/DR3 pathway.

SL-325 is a DR3 blocking antibody for the potential treatment of IBD and other inflammatory and immune-mediated diseases. In preclinical studies, SL-325 demonstrated high affinity binding to DR3 and superior potency in comparison to TL1A blocking antibodies. SL-325 blocks the TL1A binding pocket on DR3 and also interferes with trimerization of DR3. We believe that these characteristics, together with underlying biological differences in DR3 and TL1A expression, may provide a more durable blockade of the DR3/TL1A signaling axis compared to TL1A blocking antibodies.

TL1A is the sole known signaling ligand for DR3, and DR3 is the sole known signaling receptor for TL1A. Thus, we believe that the clinical safety profile of TL1A blocking antibodies generated to date (in clinical trials conducted by other parties) could de-risk the clinical safety profile for our DR3 blocking antibodies. We engineered SL-325 to lack any Fc gamma receptor binding function and SL-325 has not shown any evidence to date of antibody dependent cellular cytotoxicity or cellular phagocytosis, which further derisks the safety profile. In contrast to TL1A, DR3 is constitutively expressed by lymphocytes both in the peripheral blood and in tissues. We have demonstrated that SL-325 binds an epitope on DR3 that does not trigger receptor mediated endocytosis, and binding of SL-325 to DR3 was shown to be highly durable in preclinical assays. Thus, a pharmacodynamic biomarker of SL-325 includes direct observation of DR3 receptor occupancy on peripheral blood lymphocytes, and our pre-clinical studies suggest that blockade will last for weeks to months as a result of the properties of SL-325 and the stable expression of DR3.

DR3 and TL1A have distinct expression patterns within the small and large intestines of patients with IBD. TL1A is expressed in a pulsatile manner only in actively inflamed areas of the bowel. In contrast, DR3 is highly expressed in both inflamed and adjacent non-inflamed areas of the bowel. The absence of TL1A in non-inflamed areas of the bowel eliminates the mechanism whereby TL1A blocking antibodies would be retained in non-inflamed areas of the bowel. Because bowel inflammation observed in Crohn’s disease and ulcerative colitis can wax and wane in different areas of the bowel, stable blockade of DR3 may reduce the spread of inflammation, and contribute to higher rates of endoscopic remission.

Initial clinical development of SL-325 is planned for patients with IBD, including ulcerative colitis and Chron’s disease. The clinical success of TL1A blocking antibodies to date suggests that SL-325 will have monotherapy disease modifying activity early in clinical development. We believe that targeting DR3 may be more efficacious than targeting TL1A in patients with IBD. Additionally, the DR3/TL1A axis is implicated in a variety of other inflammatory and immune-mediated diseases. Following initial development in IBD, SL-325 may be

developed in other diseases. We expect to file an Investigational New Drug ("IND") application for SL-325 in the third quarter of 2025.

Research Programs

We maintain a strong research organization that has developed a diverse pipeline of preclinical compounds.

One of our guiding principles for considering additional pipeline candidates in oncology is a preference for compounds that we expect to have monotherapy activity early in clinical development. Through a series of studies, which were recently published in Cancer Cell, we gained an understanding of cellular targets which appear to play a pivotal role in determining acquired resistance ("AR") to immune checkpoint blockade. We reported that aberrant IFN regulation in the setting of AR suggests that tumor cell intrinsic mechanisms have conferred a growth advantage despite the presence of immune-mediated pressure unleashed by PD-1/L1 antibody blockade. Analysis of transcripts progressively upregulated during acquisition of AR in vivo and transcripts upregulated by IFN exposure of isolated AR cell lines in vitro identified the E3 ubiquitin ligase TRIM7 as a candidate mediator of the AR phenotype. Interestingly, TRIM7 is required for cell proliferation downstream of KRAS signaling as well. We have developed small molecule inhibitors ("SMI") designed to the TRIM7 PRY/SPRY viral-pocket domain, where binding specificity was confirmed using mass spec analysis. These SMI suppressed proliferation of tumor cells as monotherapy both in vitro and in vivo using preclinical models, as reported during an oral presentation at the American Association for Cancer Research Annual Meeting in 2024. We are advancing lead TRIM7 inhibitors through pre-clinical development as future internal pipeline candidates in oncology.

We have also demonstrated the feasibility of delivering certain dual-sided fusion proteins as lipid-encapsulated mRNA in a collaboration with Moderna, Inc. This work was published in Cancer Research in February 2024. We have independently extended this work to dual-sided fusion proteins in non-oncology indications, wherein mRNA/LNP based delivery methods may provide pharmacokinetic, pharmacodynamic and pharmacoeconomic advantages in comparison to traditional, intravenous delivery of recombinant proteins for chronic, non-lethal diseases. We are developing a platform of mRNA/LNP administered GLP-1 containing multifunctional constructs with potential therapeutic utility in certain cardiometabolic disorders.

Overview of Operations

Since our inception in 2016, we have devoted substantially all of our resources to conducting research and development activities, including undertaking nonclinical studies of our product candidates, conducting clinical trials of our most advanced product candidates, manufacturing our product candidates, developing and perfecting our intellectual property rights, organizing and staffing our company, business planning and raising capital. We do not have any products approved for sale, and we have not generated any revenue from product sales. We have funded our operations as of the filing date of this Quarterly Report on Form 10-Q through the net proceeds from the sale of our common stock and pre-funded warrants for approximately $262.4 million, the sale of redeemable convertible preferred stock for approximately $152.9 million, the issuance of convertible notes for approximately $10.5 million and payments received pursuant to our collaboration agreements for approximately $89.6 million.

For the nine months ended September 30, 2024 and 2023, our net loss was $56.7 million and $69.6 million, respectively. We have not been profitable since inception, and as of September 30, 2024, we had an accumulated deficit of $363.0 million and $90.1 million in cash and cash equivalents and investments. We expect to continue to incur significant expenses and operating losses in the near term in connection with our ongoing activities, as we:

•continue to advance the preclinical development and initiate Phase 1 clinical development of our product candidate, SL-325;

•initiate nonclinical studies and clinical trials for additional product candidates that we may identify in the future, including potential bi-specific DR3 antagonist antibody product candidates;

•manufacture sufficient quantities of bulk drug substance and drug product to support our ongoing and planned nonclinical studies and clinical trials;

•maintain our operational, financial, and management systems;

•retain key personnel and infrastructure to support our nonclinical development, research and manufacturing, and future clinical development efforts;

•utilize our in-house process development and manufacturing capabilities;

•continue to develop, perfect, and defend our intellectual property portfolio; and

•incur additional legal, accounting, or other expenses in operating our business, including the additional costs associated with operating as a public company and expenses incurred in connection with ongoing and future litigation, if any.

We do not expect to generate significant product revenue unless and until we successfully complete development and obtain regulatory and marketing approval of, and begin to sell, one or more of our product candidates, if ever, which we expect will take several years. We expect to spend a significant amount in development and marketing costs prior to such time. We may never succeed in achieving regulatory and marketing approval for our product candidates. We may obtain unexpected results from our nonclinical studies and clinical trials. We may elect to discontinue, delay, or modify nonclinical studies and clinical trials of our product candidates. We may be adversely affected by inflationary pressures and the macroeconomic environment, which are beyond our control. A change in the outcome of any of these variables with respect to the development of a product candidate could mean a significant change in the costs and timing associated with the development of that product candidate. Accordingly, until such time as we can generate significant product revenue, if ever, we expect to continue to seek private or public equity and debt financing, and/or additional collaborations with third parties, to meet our capital requirements. There can be no assurance that such funding may be available to us on acceptable terms, or at all, or that we will be able to commercialize our product candidates. In addition, we may not be profitable even if we commercialize any of our product candidates.

Global Economic Considerations

The global macroeconomic environment is uncertain, and could be negatively affected by, among other things, increased U.S. trade tariffs and trade disputes with other countries, instability in the global capital and credit markets, supply chain weaknesses, financial institution instability, and instability in the geopolitical environment. Such challenges have caused, and may continue to cause, recession fears, high interest rates, foreign exchange volatility and inflationary pressures. At this time, we are unable to quantify the potential effects of this economic instability on our future operations.

Components of our Results of Operations

Collaboration Revenue

We have no products approved for commercial sale, and we have not generated any revenue from commercial product sales. Our total revenue to date has been generated from our collaboration and research agreements with various third parties. Revenue recognized in 2024 was a result of collaboration agreements with Ono Pharmaceutical Co., Ltd ("Ono") and ImmunoGen, Inc. (“ImmunoGen”).

In February 2024, we entered into a collaboration and license agreement (the "Ono Agreement") pursuant to which we and Ono collaborated in the research and preclinical development of certain compounds selected by Ono from our pipeline of bifunctional fusion proteins directed toward a pair of prespecified targets for potential treatment of autoimmune and inflammatory diseases. Under the terms of the Ono Agreement, we were primarily responsible for carrying out research activities in accordance with a mutually agreed upon research plan.

Pursuant to the Ono Agreement, we granted Ono an exclusive option (the “Option”) to obtain an exclusive, sublicensable license to further research, develop, manufacture and commercialize products containing these specified bifunctional fusion proteins in any therapeutic area worldwide.

On September 30, 2024 Shattuck and Ono mutually agreed to terminate the Ono Agreement and Option pursuant to the terms of the agreement. We have completed all obligations under the agreement and have accordingly recognized $5.4 million in revenue pursuant to terms of the Ono Agreement including the $2.0 million paid for the Option. Additionally, in October 2024, the Company refunded a $1.6 million prepayment that was received in August 2024 for additional services to be performed under the Ono Agreement that was terminated before any of the additional services were performed.

As of September 30, 2024, we completed our obligations under the collaboration agreement with ImmunoGen (the “ImmunoGen Agreement”), and have recognized all revenue pursuant to the terms of that agreement.

Operating Expense

Research and Development Expense

Our research and development expenses consist primarily of costs incurred in connection with the discovery and development of our current and potential future product candidates. These expenses include:

•expenses incurred to conduct our clinical trials, including expenses associated with clinical trials of SL-172154 and the associated wind-down activities and any potential product candidates we may advance in the future, including SL-325;

•costs of manufacturing nonclinical study and clinical trial materials, including the costs of raw materials required for manufacturing;

•process development activities to optimize manufacturing processes, including the development and validation of Phase 3 and commercial manufacturing processes and analytical methods;

•expenses incurred to conduct our nonclinical studies, including research conducted on our wholly-owned compounds and those subject to the Ono Agreement;

•employee-related expenses, including salaries, benefits, and stock-based compensation;

•laboratory materials and supplies used to support our research activities;

•fees paid to third parties who assist with research and development activities;

•expenses relating to regulatory activities, including filing fees paid to regulatory agencies; and

•allocated expenses for facility-related costs

The following table summarizes our research and development expenses by product candidate:


	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands)	2024		2023		2024		2023
	(unaudited)				(unaudited)
SL-172154	$	7,160	$	10,596	$	23,430	$	22,929
Other pipeline compounds	3,210		6,075		8,845		14,359
Internal costs, including personnel related benefits, facilities and depreciation	5,943		7,540		19,541		21,795
	$	16,313	$	24,211	$	51,816	$	59,083

Research and development activities are central to our business model. Product candidates in earlier stages of development generally have lower development costs than those in later stages of development. We have discontinued clinical development of SL-172154 and are no longer conducting research activities performed under the Ono Agreement. We are now focused on the preclinical development of SL-325 and other DR3 targeted assets, and conducting additional research on other potential product candidates. As a result of these operational changes, we expect a decrease in operating expense year-over-year, primarily associated with a reduction in clinical development, manufacturing, and process development costs earmarked to SL-172154 and the reduction in costs associated with our workforce.

The process of conducting the necessary nonclinical and clinical research to obtain regulatory approval is costly and time consuming. The actual probability of success for our product candidates may be affected by a variety of factors including:

•the safety and efficacy of our product candidates;

•nonclinical data for our product candidates;

•investment in our pipeline;

•competition;

•manufacturing capability; and

•commercial viability.

We may never succeed in achieving regulatory approval for any of our product candidates due to the uncertainties discussed above. We are unable to determine the duration and completion costs of our research and development projects or when and to what extent we will generate revenue from the commercialization and sale of our product candidates, if ever.

General and Administrative Expense

General and administrative expense consists primarily of personnel expenses, including salaries, benefits, and stock-based compensation expense, for employees and consultants in executive, finance, accounting, legal, information technology, business development and human resource functions. General and administrative expense also includes corporate facility costs, including rent, utilities, depreciation, and maintenance, not otherwise included in research and development expense, as well as legal fees related to intellectual property, corporate, and litigation matters and fees for accounting and tax services.

We expect that our general and administrative expense may decrease in the future due to workforce reductions that occurred as a result of discontinuing clinical development of SL-172154. If any of our current or future product candidates advances to clinical development or obtains regulatory approval, we expect that we would incur increased expenses associated with building the appropriate general and administrative support for our increased research and development activities, or building a sales and marketing team, respectively.

Other Income

Other income consists of interest earned on our cash, cash equivalents and investments, which consists of amounts held in a money market fund and government obligations as well as investment fees and realized gain or losses on investments (if any).

Income Taxes

Since our inception, we have not recorded any income tax benefits for the net operating losses ("NOLs") we have incurred or for our research and development tax credits, as we believe, based upon the weight of available evidence, that it is more likely than not that all of our NOLs and tax credits will not be realized. Our NOLs and tax credit carryforwards have begun to expire in 2024. We have recorded a full valuation allowance against our deferred tax assets at each balance sheet date.

Results of Operations

Comparison of the Three Months Ended September 30, 2024 and 2023

The following table sets forth our results of operations for the three months ended September 30, 2024 and 2023.


	Three Months Ended September 30,				Change
(in thousands)	2024		2023		Dollar		Percentage
	(unaudited)
Collaboration revenue	$	2,997	$	686	$	2,311	336.9	%
Operating expenses:
Research and development	16,313		24,211		(7,898)		(32.6)	%
General and administrative	4,604		5,073		(469)		(9.2)	%
Loss from operations	(17,920)		(28,598)		10,678		(37.3)	%
Other income:
Other	1,245		1,057		188		17.8	%
Net loss	$	(16,675)	$	(27,541)	$	10,866	(39.5)	%

Collaboration Revenue

Collaboration revenue increased by $2.3 million, or 336.9%, to $3.0 million for the three months ended September 30, 2024 from $0.7 million for the three months ended September 30, 2023. The increase in collaboration

revenue was attributable to the research activities conducted pursuant to the Ono Agreement and recognition of the $2.0 million Option pursuant to the termination of the Ono Agreement. As of September 30, 2024 we have completed our obligations under the Ono and Immunogen agreements and have recognized all revenue pursuant to those agreements.

Research and Development Expense

Research and development expenses decreased by $7.9 million, or (32.6)%, to $16.3 million for the three months ended September 30, 2024 from $24.2 million for the three months ended September 30, 2023. The decrease in research and development expenses was primarily a result of a decrease in SL-172154 costs related to the good manufacturing practice ("GMP") manufacture of clinical trial material of $5.1 million, a 3.1 million decrease in our pipeline research, and a decrease in employee-related costs of $1.4 million, partially offset by increased clinical activity for SL-172154 of $1.7 million.

General and Administrative Expense

General and administrative expenses decreased by $0.5 million, or (9.2)%, to $4.6 million for the three months ended September 30, 2024 from $5.1 million for the three months ended September 30, 2023 as a result of a decrease in employee related cost.

Results of Operations

Comparison of the Nine Months Ended September 30, 2024 and 2023

The following table sets forth our results of operations for the nine months ended September 30, 2024 and 2023.


	Nine Months Ended September 30,				Change
(in thousands)	2024		2023		Dollar		Percentage
	(unaudited)
Collaboration revenue	$	5,721	$	943	$	4,778	506.7	%
Operating expenses:
Research and development	51,816		59,083		(7,267)		(12.3)	%
General and administrative	14,831		14,866		(35)		(0.2)	%
Loss from operations	(60,926)		(73,006)		12,080		(16.5)	%
Other income:
Other	4,195		3,395		800		(23.6)	%
Net loss	$	(56,731)	$	(69,611)	$	12,880	(18.5)	%

Collaboration Revenue

Collaboration revenue increased by $4.8 million, or 506.7%, to $5.7 million for the nine months ended September 30, 2024 from $0.9 million for the nine months ended September 30, 2023. The increase in revenue was primarily attributable to research activities performed pursuant to the Ono Agreement, recognition of the $2.0 million Option pursuant to the termination of the Ono Agreement and continued clinical activities pursuant to the ImmunoGen Agreement. As of September 30, 2024 we have completed our obligations under the Ono and ImmunoGen agreements and have recognized all revenue pursuant to those agreements.

Research and Development Expense

Research and development expenses decreased by $7.3 million, or (12.3)%, to $51.8 million for the nine months ended September 30, 2024 from $59.1 million for the nine months ended September 30, 2023. The decrease in research and development expenses was primarily a result of a decrease in expenses of $9.6 million related to preclinical research activities associated with potential product candidates and a decrease in employee-related costs $2.1 million, partially offset by an increase in the preclinical development activities associated with our DR3 programs, including SL-325, and other potential product candidates and work performed under the Ono agreement of $4.0 million, and an increase in SL-172154 clinical expense of $0.4 million.

General and Administrative Expense

General and administrative expenses remained flat for the nine months ended September 2024 compared to the nine months ended September 2023.

Liquidity and Capital Resources

Since our inception, our primary sources of liquidity have been generated by sales of our common stock, pre-funded warrants, convertible preferred stock and convertible notes, and through our collaboration and research agreements with various third parties.

In July 2022, we entered into a sales agreement ("the Sales Agreement") with Leerink Partners LLC (formerly known as SVB Securities LLC) (the "Sales Agent") pursuant to which we may offer and sell up to $75.0 million of shares of our common stock from time to time in an at-the-market facility (the "ATM Facility"). The Sales Agent is generally entitled to compensation at a commission equal to 3.0% of the aggregate gross sales price per share sold under the Sales Agreement. As of September 30, 2024, there were no sales pursuant to the ATM Facility.

Capital Resources and Funding Requirements

Our primary uses of cash and cash equivalents and investments are to fund our operations, which consist primarily of research and development expenditures related to our programs, product development costs, research expenses, administrative support, and capital expenditures related to bringing in-house certain process development and manufacturing capabilities and working capital requirements. We anticipate incurring additional net losses and negative cash flows from operations in the near future until such time, if ever, that we can generate significant sales of our product candidates currently in development. Our future funding requirements will depend on many factors, including:

•the scope, timing, progress and results of discovery, nonclinical development, laboratory testing, and clinical trials for our product candidates;

•the costs of process development and scale up of a commercially ready manufacturing process to support registrational clinical trials;

•the costs of manufacturing our product candidates for clinical trials and in preparation for marketing approval and commercialization;

•the extent to which we enter into collaborations or other arrangements with additional third parties in order to further develop our product candidates;

•the costs of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending other intellectual property-related claims;

•the costs and fees associated with the discovery, acquisition or in-license of additional product candidates or technologies;

•the costs of future commercialization activities, if any, including establishing sales, marketing, manufacturing, distribution and storage capabilities, for any of our product candidates for which we receive marketing approval; and

•revenue, if any, received from commercial sales of our product candidates, should any of our product candidates receive marketing approval.

Until we obtain regulatory approval to market our product candidates, if ever, we cannot generate revenues from sales of our products. Even if we are able to sell our products, we may not generate a sufficient amount of product revenues to finance our cash requirements. Accordingly, it will be necessary for us to seek to raise additional capital through equity offerings and/or debt financings or from other potential sources of liquidity, which may include new collaborations, licensing or other commercial agreements for one or more of our development programs or patent portfolios. Additionally, we are currently evaluating our options related to the advancement of our platform of mRNA/LNP administered multifunctional GLP-1 constructs, which may include the independent financing of a subsidiary or spun-out entity. There can be no assurance that such funding may be available to us on acceptable terms, or at all. The issuance of equity securities may result in dilution to stockholders and the issuance

of debt securities may have rights, preferences and privileges senior to those of our common stock and the terms of any such debt securities could impose significant restrictions on our operations. The failure to raise funds as and when needed could have a negative impact on our financial condition and ability to pursue our business strategies. Additionally, if additional funding is not secured when required, we may need to delay or curtail our operations until such funding is received, which would have a material and adverse impact on our business prospects and results of operations.

We believe that our cash and cash equivalents and investments as of September 30, 2024 are sufficient to fund projected operations into 2027.

Cash Flows

The following table shows a summary of our cash flows for the periods indicated:


	Nine Months Ended September 30,
(in thousands)	2024		2023
	(unaudited)
Net cash used in operating activities	$	(43,145)	$	(61,809)
Net cash provided by (used in) investing activities	(39,511)		55,008
Net cash provided by financing activities	859		54
Net decrease in cash and cash equivalents	$	(81,797)	$	(6,747)

Net Cash Used in Operating Activities

During the nine months ended September 30, 2024, net cash used in operating activities was $43.1 million and primarily reflected our net loss of $56.7 million, offset by $4.3 million in net changes to our operating assets and liabilities, and net noncash operating charges of $9.3 million for stock-based compensation, depreciation expense, accretion of investments and non-cash operating lease expense. We expect to continue to use cash in our operating activities as we conduct our clinical trials and nonclinical studies, incur costs of manufacturing clinical trial and nonclinical study materials and continue process development activities to optimize our manufacturing processes.

During the nine months ended September 30, 2023, net cash used in operating activities was $61.8 million and primarily reflected our net loss of $69.6 million offset by noncash charges of $7.8 million in stock-based compensation, depreciation expense, amortization of investments and operating lease expense.

Net Cash Provided by (Used in) Investing Activities

During the nine months ended September 30, 2024, net cash used in investing activities was $39.5 million, as a result of the net change in investments of $39.5 million.

During the nine months ended September 30, 2023, net cash provided by investing activities was $55.0 million, of which $55.4 million was the net change in investments, offset by $0.4 million in purchases of property and equipment.

Net Cash Provided by Financing Activities

During the nine months ended September 30, 2024, net cash provided by financing activities was $0.9 million and was primarily from $1.3 million in cash received for the exercise of stock options and purchases pursuant to our employee stock purchase plan offset by taxes paid related to net share settlement of equity awards of $0.5 million.

During the nine months ended September 30, 2023, minimal cash was provided by financing activities.

Contractual Obligations and Other Commitments

See Note 5 to our financial statements found elsewhere in this Quarterly Report on Form 10-Q for additional disclosures. There have been no other material changes from the Contractual Obligations and Other Commitments disclosed in Note 6 and 7 of our Annual Report on Form 10-K for the year ended December 31, 2023.

Critical Accounting Policies

Our management’s discussion and analysis of our financial condition and results of operations are based on our financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States of America. The preparation of these financial statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities and expenses and the disclosure of contingent assets and liabilities in our financial statements. On an ongoing basis, we evaluate our estimates and judgments, including those related to revenue recognition, the accrual for research and development expenses, and the valuation of stock-based awards. We base our estimates on historical experience, known trends and events, and various other factors that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions.

Our critical accounting policies are those policies which require the most significant judgments and estimates in the preparation of our financial statements. We believe that the assumptions and estimates associated with our most critical accounting policies are those relating to revenue, accrued research and development costs and stock-based compensation.

There have been no material changes in our critical accounting policies and estimates as compared to the critical accounting policies and estimates disclosed in Management’s Discussion and Analysis of Financial Condition and Results of Operations included in our Annual Report on Form 10-K for the year ended December 31, 2023.

Recent Accounting Pronouncements

See Note 2 to our financial statements found elsewhere in this Quarterly Report on Form 10-Q for a description of recent accounting pronouncements applicable to our financial statements.

Emerging Growth Company and Smaller Reporting Company Status

We are an emerging growth company as defined in the JOBS Act. Under the JOBS Act, an emerging growth company can take advantage of the extended transition period for complying with new or revised accounting standards and delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to avail ourselves of this exemption from complying with new or revised accounting standards and, therefore, will not be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies. As a result, our financial statements may not be comparable to companies that comply with new or revised accounting pronouncements as of public company effective dates.

We have evaluated the benefits of relying on other exemptions and reduced reporting requirements under the JOBS Act. Subject to certain conditions, as an emerging growth company, we may rely on certain of these exemptions, including without limitation exemptions to the requirements for (1) providing an auditor’s attestation report on our system of internal controls over financial reporting pursuant to Section 404(b) of the Sarbanes-Oxley Act and (2) complying with any requirement that may be adopted by the Public Company Accounting Oversight Board regarding mandatory audit firm rotation or a supplement to the auditor’s report providing additional information about the audit and the financial statements, known as the auditor discussion and analysis. We will remain an emerging growth company until the earlier of (a) the last day of the fiscal year (i) following the fifth anniversary of the completion of our initial public offering, (ii) in which we have total annual gross revenues of at least $1.235 billion or (iii) in which we are deemed to be a “large accelerated filer” under the rules of the SEC, which means the market value of our common stock that is held by non-affiliates exceeds $700.0 million as of the prior June 30th, or (b) the date on which we have issued more than $1.0 billion in non-convertible debt during the prior three-year period.

We are also a “smaller reporting company” as defined under the Securities and Exchange Act of 1934, as amended (the "Exchange Act"). We may continue to be a smaller reporting company if either (i) the market value of our stock held by non-affiliates is less than $250.0 million or (ii) our annual revenue is less than $100.0 million during the most recently completed fiscal year and the market value of our stock held by non-affiliates is less than $700.0 million. If we are a smaller reporting company at the time we cease to be an emerging growth company, we

may continue to rely on exemptions from certain disclosure requirements that are available to smaller reporting companies. Specifically, as a smaller reporting company we may choose to present only the two most recent fiscal years of audited financial statements in our Annual Report on Form 10-K and, similar to emerging growth companies, smaller reporting companies have reduced disclosure obligations regarding executive compensation.

Item 3. Quantitative and Qualitative Disclosures About Market Risk

We are a smaller reporting company, as defined by Rule 12b-2 under the Exchange Act and in Item 10(f)(1) of Regulation S-K, and are not required to provide the information under this item.

Item 4. Controls and Procedures

Evaluation of Disclosure Controls and Procedures

Our management, with the participation of our principal executive officer and our principal financial officer, evaluated, as of the end of the period covered by this Quarterly Report on Form 10-Q, the effectiveness of our disclosure controls and procedures. Based on this evaluation of our disclosure controls and procedures as of September 30, 2024, our principal executive officer and principal financial officer concluded that our disclosure controls and procedures as of such date are effective at the reasonable assurance level. The term “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act means controls and other procedures of a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act are recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by us in the reports we file or submit under the Exchange Act is accumulated and communicated to our management, including our principal executive officer and principal financial officer, as appropriate to allow timely decisions regarding required disclosure. Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and our management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures.

Changes in Internal Control over Financial Reporting

There were no changes in our internal control over financial reporting during the third quarter of the year ending December 31, 2024 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

PART II - OTHER INFORMATION

Item 1. Legal Proceedings

None.

Item 1A. Risk Factors

Investing in shares of our common stock involves a high degree of risk. You should carefully consider the following risks and uncertainties, together with all of the other information contained in this Quarterly Report on Form 10-Q and in our other filings with the SEC before making an investment decision. The occurrence of any of the following risks could materially and adversely affect our business, financial condition, reputation, or results of operations. In such case, the trading price of shares of our common stock could decline, and you may lose all or part of your investment. It is not possible to predict or identify all such risks; our operations could also be affected by factors, events or uncertainties that are not presently known to us or that we currently do not consider to present significant risks to our operations. Therefore, you should not consider the following risks to be a complete statement of all the potential risks or uncertainties that we face.

Summary of Key Risk Factors

•We are a preclinical-stage biotechnology company and have incurred significant losses since our inception, and we expect to incur losses for the foreseeable future. We have no products approved for commercial sale, have never generated revenue from product sales, and may never achieve or maintain profitability.

•We will require additional funding in order to complete development of our product candidate(s), including SL-325, and commercialize our products, if approved. Additional funding may not be available on acceptable terms, or at all. If we are unable to raise capital when needed, we could be forced to delay, reduce, or eliminate our product development programs and any future clinical trials, our efforts to access manufacturing capacity, and any commercialization efforts.

•Raising additional capital may cause dilution to our existing stockholders, restrict our operations, or require us to relinquish rights to our technologies or product candidates.

•Our limited operating history may make it difficult for you to evaluate the success of our business to date and to assess our future viability.

•We are substantially dependent on the success of our product candidate, SL-325, and our anticipated clinical trials of such product candidate may not be successful.

•Our product candidate(s) are in preclinical stages of development and may fail in development or suffer delays. We depend on the successful initiation and completion of clinical trials for our product candidates to advance our product development plans.

•Our clinical trials may fail to demonstrate substantial evidence of the safety and efficacy of our product candidate(s) or any future product candidates, which would prevent or delay or limit both the scope of regulatory approval and our ability to successfully commercialize.

•Preclinical and clinical development is a lengthy and expensive process that is subject to delays and uncertain outcomes, and results of earlier studies and trials may not be predictive of future clinical trial results. If preclinical studies and clinical trials of our product candidate(s) are prolonged or delayed, we may be unable to obtain required regulatory approvals, and, therefore, be unable to complete the development of and commercialize our product candidate(s) on a timely basis or at all.

•We may not be successful in our efforts to identify or discover additional product candidates.

•We face competition from entities that have developed or may develop programs for the diseases addressed by product candidates developed by us.

•Our product candidate(s) may have serious adverse, undesirable, or unacceptable side effects or other properties that may delay or prevent marketing approval.

•If we experience delays or difficulties initiating clinical trial sites or enrolling patients in our planned clinical trials, our research and development efforts, business, financial condition, and results of operations could be materially and adversely affected.

•The development and commercialization of biopharmaceutical products is subject to extensive regulation, and the regulatory approval processes of the FDA and comparable foreign authorities are lengthy, time-consuming, and inherently unpredictable. If we are ultimately unable to obtain regulatory approval for our product candidate(s) on a timely basis, if at all, our business will be substantially harmed. We operate in highly-competitive and rapidly-changing industries, which may result in others discovering, developing, or commercializing competing products before or more successfully than we do.

•We rely on third parties to supply raw materials and to manufacture our product candidate(s). The manufacture of our product candidate(s) is complex and our third-party manufacturers may encounter difficulties in production, which could delay or entirely halt their ability to supply our product candidate(s) for clinical trials or, if approved, for commercial sale.

•Our success depends upon our ability to obtain and maintain patents and other intellectual property rights to protect our technology, including SL-325, methods used to manufacture those product candidate(s), formulations thereof, and the methods for treating patients using those product candidate(s).

•Economic downturns, inflation, fluctuating interest rates, natural disasters, public health crises such as pandemics or other events could materially and adversely affect our business operations, workforce, product development activities, research and development activities, preclinical and clinical trials, and financial condition.

Risks Related to Our Business, Our Financial Condition and Capital Requirements

We are a preclinical-stage biotechnology company and have incurred significant losses since our inception, and we expect to incur losses for the foreseeable future. We have no products approved for commercial sale, have never generated revenue from product sales, and may never achieve or maintain profitability.

We are a preclinical stage biotechnology company and will need to raise substantial additional capital to continue to fund our operations in the future. We have based our estimates on assumptions that may prove to be wrong, and could exhaust our available financial resources sooner than we currently anticipate.

Biotechnology product development is a highly speculative undertaking and involves a substantial degree of risk. We have incurred significant operating losses since inception. For the nine months ended September 3, 2024 and 2023, we reported a net loss of $56.7 million and $69.6 million, respectively. As of September 330, 2024, we had an accumulated deficit of $363.0 million. We expect to continue to incur significant operating losses for the foreseeable future, including as our product candidate(s) enter clinical trials. We expect to invest significant funds into the research and development of our current programs to determine the potential to advance product candidate(s) to regulatory approval. To become and remain profitable, we must succeed in developing and eventually commercializing products that generate significant revenue. We may never succeed in these activities and, even if we do, we may never generate revenue that is sufficient to achieve profitability.

We expect to continue to incur significant expenses and increasing operating losses for the foreseeable future and our expenses will increase substantially if and as we:

•continue the preclinical development and initiate the clinical development of our lead product candidate, SL-325;

•continue efforts to discover and develop new product candidates;

•continue the manufacturing of our product candidate(s) or increase volumes manufactured by third parties;

•initiate additional preclinical and nonclinical studies or clinical trials for our product candidate(s);

•seek regulatory and marketing approvals for our product candidate(s)

•establish a sales, marketing, and distribution infrastructure to commercialize any products for which it may obtain marketing approval and market for ourselves;

•see to maintain, protect, and expand our intellectual property portfolio; and

•experience any delays or encounter issues with the development and potential regulatory approval of our clinical and product candidate(s) such as safety issues, manufacturing delays, clinical trial accrual delays, longer follow-up for planned studies or trials, additional major studies or trials, or supportive trials necessary to support marketing approval.

We will require additional funding in order to complete development of our product candidate(s), including SL-325, and commercialize our products, if approved. Additional funding may not be available on acceptable terms, or at all. If we are unable to raise capital when needed, we could be forced to delay, reduce, or eliminate our product development programs and other operations.

Based on our current business plans, we estimate that our existing cash and cash equivalents and investments will enable us to fund our operating expenses into 2027. We have based this estimate on assumptions that may prove to be wrong, and we could use our capital resources sooner than we currently expect, requiring us to seek additional funds sooner than planned through public or private equity or debt financings or other sources, such as strategic collaborations. In addition, we may seek additional capital due to favorable market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. Attempting to secure additional financing may divert our management from our day-to-day activities, which may materially and adversely affect the development of our product candidates. Our ability to raise additional funds will depend on financial, economic, and market conditions and other factors, over which we may have no or limited control. Additional funds may not be available when we need them, on terms that are acceptable to us or at all.

Raising additional capital may cause dilution to our existing stockholders, restrict our operations, or require us to relinquish rights to our technologies or product candidate(s).

If we raise additional capital through the sale of equity, including through our “at-the-market” offerings (the “ATM Facility”), or convertible debt securities, the ownership interests of existing stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect our existing stockholders’ rights as holders of our common stock. In addition, the possibility of such issuance may cause the market price of our common stock to decline. Debt financing, if available, may result in increased fixed payment obligations and involve agreements that include covenants limiting or restricting our ability to take certain actions, such as incurring additional debt, making capital expenditures, making additional product acquisitions, or declaring dividends, which could materially and adversely impact our ability to conduct our business.

If we raise additional funds through collaborations, strategic alliances or marketing, distribution or licensing arrangements with third parties, we may be required to relinquish valuable rights to our research programs or product candidate(s) or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings or other arrangements with third parties when needed, we may be required to delay, limit, reduce or terminate our product development or future commercialization efforts or grant rights to third parties to develop and market product candidate(s) that we would otherwise prefer to develop and market ourselves.

Our ability to compete depends on retaining our key personnel and recruiting additional qualified personnel.

Our success depends upon the continued contributions of our key management, scientific, and technical personnel, many of whom have been instrumental for us and have substantial experience with our product candidate(s) and related technologies. Although we have employment agreements with certain of our key employees, including our Chief Executive Officer, these employment agreements provide for at-will employment, which means that any of our employees could leave our employment at any time, with or without notice.

In the future, we expect to experience periods of growth in the number of our employees and the scope of our operations, particularly in the areas of drug development, clinical operations, business development, manufacturing, regulatory affairs, quality assurance, human resources, legal, accounting and finance, and, ultimately, sales and marketing. The competition for qualified personnel in the biotechnology and pharmaceutical industries is intense, and our future success depends upon our ability to attract, retain, and motivate highly skilled scientific, technical, and managerial employees. If our recruitment and retention efforts are unsuccessful, when needed, in the future, it may be difficult for us to implement our business strategy, which could have a material adverse effect on our business.

To manage any future growth, we must continue to implement and improve our managerial, operational, and financial systems, and expand our facilities. Due to our limited financial resources and the limited experience of our management team in managing a growing company, we may not be able to effectively manage the expansion of our operations systems and facilities. These activities may lead to significant costs and may divert our management and other resources. Any inability to manage growth could delay the execution of our business plans or disrupt our operations.

In addition, we are a small company with limited resources, our business prospects are uncertain, and our stock price is volatile. For some or all of the foregoing reasons, we may not be able to recruit all of the management, technical, and other personnel that we require or we may be unable to retain all of our existing personnel. In such event, we may be required to limit our growth and expansion efforts and our business and financial results may suffer.

Our limited operating history may make it difficult for you to evaluate the success of our business to date and to assess our future viability.

Since our inception in 2016, we have devoted a significant portion of our resources to developing our product candidates, our other research and development efforts, building our intellectual property portfolio, raising capital, and providing general and administrative support for these operations. We have not yet demonstrated our ability to successfully complete product development activities, complete clinical trials (including Phase 3 or other pivotal clinical trials), obtain regulatory approvals, manufacture a commercial-scale product or arrange for a third-party to

do so on our behalf, or conduct sales and marketing activities necessary for successful product commercialization. Additionally, we expect our financial condition and operating results to continue to fluctuate significantly from period to period due to a variety of factors, many of which are beyond our control. Consequently, any predictions you or we may make about our future success or viability may not be as accurate as they could be if we had a longer operating history.

Risks Related to the Development and Clinical Testing of Our Product Candidates

We are substantially dependent on the success of our lead product candidate, SL-325, and our anticipated clinical trials of such product candidate(s) may not be successful.

Our lead product candidate, SL-325, is in preclinical development, and if that product candidate is not successful, our business could be materially impacted. While we have other preclinical programs, there is no guarantee that these programs will advance into clinical development. Our future success is substantially dependent on our ability to develop and timely obtain marketing approval for, and then successfully commercialize, SL-325. We are investing the majority of our efforts and financial resources into the research and development of SL-325 and other DR3 antagonists, including bispecific antibodies targeting DR3 together with another biologically relevant target.

Our pipeline candidates are in the early stages of development and will require substantial preclinical and clinical development and testing, manufacturing process development, improvement and validation, and regulatory approval prior to commercialization and before we generate any revenues from product sales. The success of our product candidate(s) will depend on a variety of factors. We do not have complete control over many of these factors, including certain aspects of clinical development and the regulatory submission process, potential threats to our intellectual property rights and the manufacturing, marketing, distribution and sales efforts of any future collaborator.

Of the large number biologics and drugs in development in the pharmaceutical industry, only a small percentage result in the submission of a biologics license application (“BLA”) to the FDA or marketing authorization application (“MAA”) to the European Medicines Agency (“EMA”), and even fewer are approved for commercialization. Furthermore, even if we do receive regulatory approval to market any of our product candidates, any such approval may be subject to limitations on the indicated uses for which we may market the product, or limitations related to its distribution, or be conditional on future development activities and clinical results. Accordingly, even if we are able to obtain the requisite financing to continue to fund our development programs, there can be no assurance that any of our product candidates will be successfully developed or commercialized. If we or any of our future development partners are unable to develop, or obtain regulatory approval, or, if approved, successfully commercialize, any of our product candidates, we may not be able to generate sufficient revenue to continue the operation of our business.

Our product candidate(s) are in preclinical stages of development and may fail in development or suffer delays. We depend on the successful initiation and completion of clinical trials for our product candidate(s) to advance our product development plans.

We have no products on the market, and our product candidate(s) are in preclinical stages of development and have not been tested in humans. As a result, we expect it will be years before we can obtain regulatory approval for and commercialize any product candidate, if ever. We must initiate and complete clinical trials that demonstrate the safety and efficacy of our product candidates in humans, and we do not yet know if our lead product candidate, SL‑325, will be safe or effective in humans. Clinical testing is expensive, difficult to design and implement, and can take years to complete and is uncertain as to outcome. A failure of one or more of our clinical trials can occur at any stage of testing. The outcome of preclinical testing and early clinical trials may not be predictive of the success of later clinical trials, and interim results of a clinical trial do not necessarily predict final results. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that have believed their product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval for their products.

Preclinical and clinical development is a lengthy and expensive process that is subject to delays and uncertain outcomes, and results of earlier preclinical studies and clinical trials may not be predictive of future clinical trial results. If preclinical studies and clinical trials of our product candidate(s) are prolonged or delayed, we may be

unable to obtain required regulatory approvals, and, therefore, be unable to complete the development of and commercialize our product candidate(s) on a timely basis or at all.

It is impossible to predict when or if any of our product candidate(s) will prove safe and effective in humans or will receive regulatory approval. Before obtaining marketing approval from regulatory authorities for the sale of any drug candidate, we must complete preclinical studies and then conduct extensive clinical trials to demonstrate the safety and efficacy of our product candidate(s) in humans. Our clinical trials may not be conducted as planned or completed on schedule, if at all, and a failure can occur at any time or stage of the preclinical study or clinical trial process. Additionally, there is no guarantee that our IND filing(s) will be accepted by the FDA, or comparable foreign regulatory authorities, or that these filings(s) will be accepted within our expected timelines. The outcome of preclinical studies and early-stage clinical trials may not be predictive of the success of later clinical trials, and interim results of a clinical trial do not necessarily predict final results. The design of a clinical trial can determine whether its results will support approval of a product candidate, and flaws in the design of a clinical trial may not become apparent until the clinical trial is well advanced. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that have believed their compounds and product candidates performed satisfactorily in preclinical studies and clinical trials have nonetheless failed to obtain marketing approval of their product candidates. In addition, the results of our preclinical animal studies, including our non-human primate studies, may not be predictive of the results of outcomes in subsequent clinical trials on human subjects. Product candidates in clinical trials may fail to show the desired pharmacological properties or safety and efficacy traits despite having progressed through preclinical studies.

We could also encounter delays if a clinical trial is suspended or terminated by us, by the independent institutional review boards of the institutions in which such clinical trials are being conducted, by the Data Safety Monitoring Board, if any, for such clinical trial, or by the FDA or other regulatory authorities. Such authorities may suspend or terminate a clinical trial due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements or our clinical trial protocols, inspection of the clinical trial operations or trial site by the FDA or other regulatory authorities resulting in the imposition of a clinical hold, unforeseen safety issues or adverse side effects, failure to demonstrate a benefit from the product candidates, changes in governmental regulations or administrative actions, or lack of adequate funding to continue the clinical trial. If we are required to conduct additional clinical trials or other testing of our product candidate(s) beyond those that we currently contemplate, if we are unable to successfully complete clinical trials of our product candidate(s), if the results of these trials are not positive or are only moderately positive, or if there are safety concerns, our business and results of operations may be materially and adversely affected, and we may incur significant additional costs.

Our clinical trials may fail to demonstrate substantial evidence of the safety and efficacy of our product candidates or any future product candidates, which would prevent, delay or limit both the scope of regulatory approval and our ability to successfully commercialize.

To obtain the requisite regulatory approvals to market and sell any product candidates, we must demonstrate through extensive preclinical studies and clinical trials that our compounds and investigational drug products are safe and effective for use in each targeted indication in humans. Clinical testing is expensive and takes many years to complete, and its outcome is inherently uncertain. The process of obtaining regulatory approval is expensive, often taking many years following the commencement of clinical trials, and can vary substantially based upon the type, complexity, and novelty of the product candidates involved, as well as the target indications, patient population, and regulatory agency.

Clinical trials that we conduct may not demonstrate the efficacy and safety that is necessary to obtain regulatory approval to market our product candidate(s). If the results of our future clinical trials are inconclusive with respect to the efficacy of our product candidate(s), if we do not meet the clinical endpoints with statistical and clinically meaningful significance, or if there are safety concerns associated with our product candidate(s), we may be delayed in obtaining marketing approval, if at all. Additionally, any safety concerns observed in any one of our future clinical trials could limit the prospects for regulatory approval of that product candidate or other product candidates in any indications. Even if our clinical trials are successfully completed, clinical data are often susceptible to varying interpretations and analyses, and we cannot guarantee that the FDA or comparable foreign regulatory authorities will interpret the results as we do, and more trials could be required before we are able to submit our product candidate(s) for approval. Moreover, results that are acceptable to support approval in one

jurisdiction may be deemed inadequate to support regulatory approval in other jurisdictions. Even if regulatory approval is secured for a product candidate, the terms of such approval may limit the scope and use of the specific product candidate in a manner that does not meet our expectations, which limitations may reduce its commercial potential.

We may not be successful in our efforts to identify or discover additional product candidates.

The success of our business depends primarily upon our ability to identify, develop and commercialize products. Our research programs may fail to identify other potential product candidates for clinical development for a number of reasons. For example, our research methodology may be unsuccessful in identifying potential product candidates or our potential product candidates may be shown to lack efficacy, have harmful side effects, or may have other characteristics that may make the products unmarketable or unlikely to receive marketing approval.

If any of these events occur, we may be forced to abandon our development efforts for a program or programs, which could have a material adverse effect on our business, financial condition, results of operations, and prospects. Research programs to identify new product candidates require substantial technical, financial and human resources. We may focus our efforts and resources on potential programs or product candidates that may ultimately prove to be unsuccessful.

We face competition from entities that have developed or may develop programs for the diseases addressed by product candidate(s) developed by us.

The development and commercialization of drugs is highly competitive. Product candidate(s) developed by us, if approved, will face significant competition and our failure to effectively compete may prevent us from achieving significant market penetration. We compete with a variety of biopharmaceutical companies as well as academic institutions, governmental agencies, and public and private research institutions, among others. Many of the companies with which we are currently competing or will compete against in the future have significantly greater financial resources and expertise in research and development, manufacturing, preclinical testing, clinical trials, regulatory approvals, and marketing than we do. Mergers and acquisitions in the pharmaceutical and biotechnology industry may result in even more resources being concentrated among a smaller number of our competitors. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These competitors also compete with us in recruiting and retaining qualified scientific and management personnel, establishing clinical trial sites, recruiting participants for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our product candidate(s).

Our competitors have developed, are developing or will develop programs and processes competitive with our programs and processes. Competitive therapeutic treatments include those that have already been approved and accepted by the medical community and any new treatments. Our success will depend partially on our ability to develop and commercialize products that have a competitive safety, efficacy, dosing and/or presentation profile. Our commercial opportunity and success will be reduced or eliminated if competing products are safer, more effective, have a more attractive dosing profile or presentation or are less expensive than the products we develop, or if our competitors develop competing products or if biosimilars enter the market more quickly than we do and are able to gain market acceptance.

Our product candidate(s) may have serious adverse, undesirable, or unacceptable side effects or other properties that may delay or prevent marketing approval and our ability to market and derive revenue from our product candidate(s) could be compromised.

Undesirable side effects that may be caused by our product candidate(s) could cause us or regulatory authorities to interrupt, delay, or halt clinical trials and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or other comparable foreign authorities. Our lead product candidate, SL-325 has not been tested in humans, and we do not yet know if it will have serious, undesirable, or unacceptable side effects. Results of our preclinical studies or clinical trials could reveal a high and unacceptable severity and/or prevalence of side effects. In such an event, our clinical trials could be suspended or terminated and the FDA or comparable foreign authorities could order us to cease further development or deny approval of our product candidate(s) for any or all targeted indications. The drug-related side effects could affect patient recruitment or the ability of enrolled patients to complete the clinical trial or result in potential product liability claims. Any of these occurrences may significantly harm our business, financial condition and results of operations.

Further, clinical trials by their nature utilize a sample of the potential patient population. With a limited number of patients and limited duration of exposure, rare and severe side effects of our product candidate(s) may only be uncovered with a significantly larger number of patients exposed to the product candidate.

If we experience delays or difficulties initiating clinical trial sites or enrolling patients in our planned clinical trials, our research and development efforts, business, financial condition, and results of operations could be materially and adversely affected.

We have not yet initiated clinical trials for our lead product candidate, SL-325. Successful and timely completion of our planned clinical trials will require that we initiate our clinical trial sites in a timely manner and enroll a sufficient number of patient candidates. Trials may be subject to delays for a variety of reasons, including as a result of delays to clinical trial site start up and initiation, patient enrollment taking longer than anticipated, fewer than expected patients who meet enrollment eligibility criteria, patient withdrawal, or AEs. Our clinical trials may compete with other clinical trials that are in the same therapeutic areas as our product candidate(s) and/or that seek to enroll the same specific patient populations as our clinical trials, which reduces the number and types of patients available to us. We may also compete with head-to-head clinical trials, in which patients may prefer to participate, which may further reduce the number of patients available to us.

If we are unable to initiate or adequately enroll our clinical trial sites, our clinical trials may be delayed. Receiving approval for and establishing clinical trial sites in other countries may be more challenging or lengthy than in the United States. As a result of any of the aforementioned factors, we may in the future decide to use clinical trial sites in other parts of the world. It may be more difficult to control international clinical trials and the results may be less reliable. In addition, if the international clinical trial was conducted in a country with lower quality healthcare than in developed countries, the patients may experience side effects not experienced by patients in developed countries.

Delays in the completion of any clinical trial of our product candidate(s) will increase our costs, slow down our product candidate development and approval process, and delay or potentially jeopardize our ability to commence product sales and generate revenue. In addition, some of the factors that cause, or lead to, a delay in the commencement or completion of clinical trials may also ultimately lead to the denial of regulatory approval of our product candidate(s).

We may expend our limited resources to pursue a particular product candidate and fail to capitalize on product candidates that may be more profitable or for which there is a greater likelihood of success.

Because we have limited financial resources, we focus our research and development efforts on certain selected product candidate(s), including SL-325. As a result, we may forgo or delay pursuit of opportunities with other product candidates that later prove to have greater commercial potential. Our resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market opportunities. Our spending on current and future research and development programs and product candidates for specific indications may not yield any commercially viable product candidates. In addition, if we do not accurately evaluate the commercial potential or target market for a particular product candidate, we may relinquish valuable rights to that product candidate through collaboration, licensing, or other royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate.

Risks Related to Our Regulatory Environment

The development and commercialization of biopharmaceutical products is subject to extensive regulation, and the regulatory approval processes of the FDA and comparable foreign authorities are lengthy, time-consuming, and inherently unpredictable. If we are ultimately unable to obtain regulatory approval for our product candidate(s) on a timely basis, if at all, our business will be substantially harmed.

The clinical development, manufacturing, labeling, packaging, storage, recordkeeping, advertising, promotion, export, import, marketing, distribution, adverse event reporting (including the submission of safety and other post-marketing information and reports), and other possible activities relating to our product candidate(s) are subject to extensive regulation by the FDA and by comparable regulatory authorities outside the United States. Obtaining approval of a BLA can be a lengthy, expensive, and uncertain process, and as a company we have no experience with the preparation of a BLA submission or any other application for marketing approval. This lengthy

approval process may result in our failing to obtain regulatory approval to market any of our product candidates, which would significantly harm our business, results of operations, and prospects. See “Business-Government Regulation-BLA Submission and Review” in our Annual Report on Form 10-K.

In addition, the FDA or comparable foreign authorities may change the requirements for clinical development and approval, which may alter our clinical development plans and increase our costs. If the FDA does not believe we have sufficiently demonstrated that the selected doses for our product candidates maximize not only the efficacy of such candidate, but the safety and tolerability as well, our ability to progress our clinical trials and ultimately commercialize a product candidate may be delayed and our costs may be increased.

Any regulatory approvals that we may receive for our programs will require the submission of reports to regulatory authorities and surveillance to monitor the safety and efficacy of the program, may contain significant limitations related to use restrictions for specified age groups, warnings, precautions or contraindications, and may include burdensome post-approval study or risk management requirements. For example, the FDA may require a risk evaluation and mitigation strategy in order to approve our programs, which could entail requirements for a medication guide, physician training and communication plans or additional elements to ensure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. In addition, if the FDA or comparable foreign regulatory authorities approve our programs, our programs and the activities associated with their development and commercialization, including their design, testing, manufacture, safety, efficacy, recordkeeping, labeling, storage, approval, advertising, promotion, sale, distribution, import and export will be subject to comprehensive regulation by the FDA and other regulatory agencies in the United States and by comparable foreign regulatory authorities. These requirements include submissions of safety and other post-marketing information and reports, registration, as well as on-going compliance with current cGMPs and GCPs for any clinical trials that we conduct following approval.

If we or a regulatory authority discover previously unknown problems with a product, such as adverse events of unanticipated severity or frequency, or problems with the facilities where the product is manufactured, a regulatory authority may impose restrictions on that product, the manufacturing facility or us, including requiring recall or withdrawal of the product from the market or suspension of manufacturing, restrictions on our ability to conduct clinical trials, including full or partial clinical holds on ongoing or planned trials, restrictions on the manufacturing process, warning or untitled letters, civil and criminal penalties, injunctions, product seizures, detentions or import bans, voluntary or mandatory publicity requirements and imposition of restrictions on operations, including costly new manufacturing requirements. The occurrence of any event or penalty described above may inhibit our ability to commercialize our product candidate(s) and generate revenue and could require us to expend significant time and resources in response and could generate negative publicity.

Our product candidates for which we intend to seek approval as biologics may face competition sooner than anticipated.

The Patient Protection and Affordable Act, as amended by the Healthcare and Education Reconciliation Act (the “ACA”), includes a subtitle called the Biologics Price Competition and Innovation Act of 2009 (“BPCIA”), which created an abbreviated approval pathway for biological products that are biosimilar to or interchangeable with an FDA-licensed reference biological product. Under the BPCIA, an application for a highly similar or “biosimilar” product may not be submitted to the FDA until four years following the date that the reference product was first approved by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first approved. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing the sponsor’s own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of their product.

We believe that our product candidate(s) approved as biologics under a BLA should qualify for the 12-year period of exclusivity. However, there is a risk that this exclusivity could be shortened due to congressional action or otherwise, or that the FDA will not consider our product candidate(s) to be reference products for competing products, potentially creating the opportunity for competition sooner than anticipated. Other aspects of the BPCIA, some of which may impact the BPCIA exclusivity provisions, have also been the subject of recent litigation. Moreover, the extent to which a biosimilar, once approved, will be substituted for any reference products in a way

that is similar to traditional generic substitution for non-biological products is not yet clear, and will depend on a number of marketplace and regulatory factors that are still developing.

We may not be able to meet requirements for the chemistry, manufacturing and control of our programs.

In order to receive approval of our products by the FDA and comparable foreign regulatory authorities, we must show that we and our CMO partners are able to characterize, control and manufacture our drug products safely and in accordance with regulatory requirements. This includes manufacturing the active ingredient, developing an acceptable formulation, manufacturing the drug product, performing tests to adequately characterize the formulated product, documenting a repeatable manufacturing process, and demonstrating that our drug products meet stability requirements. Meeting these chemistry, manufacturing and control requirements is a complex task that requires specialized expertise. We are currently developing the manufacturing process for our lead product candidate, SL‑325 and we have not yet transferred a manufacturing process for our lead product candidate, SL-325, to a third-party CMO, and if we are not able to meet the chemistry, manufacturing and control requirements, we may not be successful in getting our products, including SL-325, approved.

Disruptions at the FDA and other government agencies could negatively affect the review of our regulatory submissions, which could negatively impact our business.

The ability of the FDA to review and approve regulatory submissions can be affected by a variety of factors, including disruptions caused by government shutdowns, changes in leadership at FDA and/or the department of health and human services, and public health crises. Such disruptions could significantly impact the ability of the FDA or other regulatory authorities to timely review and process our regulatory submissions, which could have a material adverse effect on our business.

Our research and development activities could be affected or delayed as a result of possible restrictions on animal testing.

Certain laws and regulations require us to test our compounds on animals before initiating clinical trials involving humans. To the extent the activities of animal rights groups are successful, our research and development activities may be interrupted, delayed, or become more expensive.

Current and future laws and regulations may increase the difficulty and cost for us, and any collaborators, to obtain marketing approval of and commercialize our drug candidates and affect the prices we, or they, may obtain.

Heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products has resulted in several recent Congressional inquiries and proposed and enacted federal and state legislation designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for products. We expect that additional state and federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that federal and state governments will pay for healthcare therapies, which could result in reduced demand for our product candidate(s) or additional pricing pressures. In August 2022, President Biden signed into law the IRA, which, among other provisions, included several measures intended to lower the cost of prescription drugs and enact related healthcare reforms. We cannot be sure whether additional legislation or rulemaking related to the IRA will be issued or enacted, or what impact, if any, such changes will have on the profitability of any of our drug candidates, if approved for commercial use, in the future.

Our business operations and current and future relationships with healthcare professionals, principal investigators, consultants, vendors, customers, and third-party payors are subject to applicable healthcare laws, which could expose us to penalties.

Our business operations and current and future arrangements with investigators, healthcare professionals, consultants, third-party payors, patient organizations, and customers may expose us to broadly applicable fraud and abuse and other healthcare laws and regulations. These laws may constrain the business or financial arrangements and relationships through which we conduct our operations, including how we research, market, sell, and distribute our product candidate(s), if approved. See “Business-Government Regulation-Other Healthcare Laws and Compliance Requirements” in our Annual Report on Form 10-K for a more detailed description of the laws that may affect our ability to operate.

Ensuring that our internal operations and future business arrangements with third parties comply with applicable healthcare laws and regulations will involve substantial costs. If our operations are found to be in violation of any of these laws or any other governmental laws and regulations that may apply to us, we may be subject to significant penalties, including civil, criminal, and administrative penalties, as well as damages, fines, exclusion from government-funded healthcare programs, integrity oversight and reporting obligations to resolve allegations of non-compliance, disgorgement, individual imprisonment, contractual damages, reputational harm, diminished profits, and the curtailment or restructuring of our operations. Further, defending against any such actions can be costly, time-consuming, may require significant personnel resources, and may impair our business even if we are successful in defending against such claims. Therefore, even if we are successful in defending against any such actions that may be brought against us, our business may be impaired.

Our employees, independent contractors, principal investigators, contract research organizations (“CROs”), consultants, commercial partners, suppliers, and vendors acting for us or on our behalf may engage in misconduct or other improper activities, including noncompliance with applicable laws and regulations.

We have adopted a code of conduct, but it is not always possible to identify and deter such misconduct, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to comply with these laws or regulations.

If we fail to comply with environmental, health and safety laws and regulations, we could become subject to fines or penalties or incur costs that could have a material adverse effect on the success of our business.

We are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. Our operations may involve the use of hazardous and flammable materials, including chemicals and biological and radioactive materials. In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. These current or future laws and regulations may impair our research, development or commercialization efforts. Failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions.

Risks Related to Our Dependence on Third Parties

We rely on third parties to supply raw materials and to manufacture our product candidate(s). The manufacture of our product candidate(s) is complex and our third-party manufacturers may encounter difficulties in production, which could delay or entirely halt their ability to supply our product candidate(s) for clinical trials or, if approved, for commercial sale.

The process of manufacturing our current and future product candidates is complex and highly regulated. We do not currently own or operate any cGMP manufacturing facilities, and we do not currently have any in-house cGMP manufacturing capabilities. Consequently, we expect to rely on third-party contract manufacturers to produce sufficient quantities of our current and future product candidates for preclinical testing and clinical trials, in compliance with applicable regulatory and quality standards. We have not yet transferred the manufacturing process for our lead product candidate, SL-325, to a third-party contract manufacturer and there can be no assurance that a manufacturer will be able to successfully produce satisfactory product on a timely basis. With legacy programs in the past, the manufacture of our product candidates by third-party manufacturers has, in the normal course of business, been negatively impacted by equipment failure, improper installation or operation of equipment, vendor or operator error, inconsistency in yields, variability in product characteristics, and difficulties in scaling the production process. If we are unable to successfully and timely produce sufficient supply of our current and future product candidates, our planned clinical trials may be delayed and materially and adversely harm our business.

As part of our process development efforts, we also may make changes to our manufacturing processes at various points during development for various reasons, such as controlling costs, achieving scale, decreasing processing time, increasing manufacturing success rate, or other reasons. We have invested in an in-house process development pilot plant to reduce our reliance on third parties for our process development efforts, however we cannot guarantee that these efforts will result in useful changes to our manufacturing processes. Any changes to our manufacturing processes carry the risk that they will not achieve their intended objectives, and any of these changes could cause our product candidate(s) to perform differently and affect the results of our ongoing clinical trials or

future clinical trials. In some circumstances, changes in the manufacturing process may require us to perform ex vivo comparability studies and to collect additional data from patients prior to undertaking more advanced clinical trials.

In addition, the FDA and other regulatory authorities require that our product candidate(s) be manufactured according to cGMPs and similar foreign standards relating to methods, facilities, and controls used in the manufacturing, processing, packing, storage, and distribution of the product, which are intended to ensure that biological products are safe and that they consistently meet applicable requirements and specifications. We are dependent on third parties for all of these activities, and we have limited ability to prevent or control the risk that such activities will not be in compliance with cGMP. In addition, the storage and distribution of our product candidate(s) for use in clinical trials is subject to extensive regulation by the FDA and other regulatory authorities. Any failure by our third-party manufacturers to comply with cGMP or failure to scale up manufacturing processes, including any failure to deliver sufficient quantities of product candidate(s) in a timely manner, could lead to a delay in our clinical trials and development efforts, or a delay in or failure to obtain regulatory approval of any of our product candidate(s).

Pharmaceutical manufacturers are also subject to extensive oversight by the FDA and comparable regulatory authorities in other jurisdictions, which include continual review and periodic unannounced and announced inspections by the FDA to assess compliance with cGMP requirements. If an FDA inspection of a manufacturer’s facilities reveals conditions that the FDA determines not to comply with applicable regulatory requirements, the FDA may issue observations through a Notice of Inspectional Observations, commonly referred to as a “Form FDA 483” report. If observations in the Form FDA 483 report are not addressed in a timely manner and to the FDA’s satisfaction, the FDA may issue a Warning Letter or proceed directly to other forms of enforcement action. Any failure by one of our contract manufacturers to comply with cGMP or to provide adequate and timely corrective actions in response to deficiencies identified in a regulatory inspection could result in further enforcement action that could lead to a shortage of products and harm our business. The failure of a manufacturer to address any concerns raised by the FDA or foreign regulators could also lead to plant shutdown or the delay or withholding of product approval by the FDA in additional indications, or by foreign regulators in any indication. Moreover, if the FDA determines that our third-party manufacturers are not in compliance with applicable laws and regulations, including those governing cGMPs, the FDA may deny BLA approval until the deficiencies are corrected or we replace the manufacturer in our BLA with a manufacturer that is in compliance. Certain countries may impose additional requirements on the manufacturing of drug products or drug substances, and on manufacturers, as part of the regulatory approval process for products in such countries. The failure by our third-party manufacturers to satisfy such requirements could impact our ability to obtain or maintain approval of our products in such countries.

We rely, and expect to continue to rely, on third parties to conduct preclinical studies, nonclinical studies, and clinical trials. If these third parties do not successfully carry out their contractual duties, comply with applicable regulatory requirements, or meet expected deadlines, we may not be able to obtain regulatory authorizations or approvals required to develop or commercialize our product candidate(s) and our business could be materially and adversely affected.

We have relied, and plan to continue to rely, upon third parties, including independent clinical investigators and third-party CROs, to help establish and conduct certain preclinical studies, nonclinical studies, and future clinical trials and to monitor, record, and manage data for our ongoing preclinical and nonclinical programs and future clinical programs. We currently and in future expect to rely on these parties for execution of certain preclinical studies and clinical trials, and control only certain aspects of their activities. As a result, we will have less direct control over the conduct, timing, and completion of these preclinical studies, nonclinical studies, and clinical trials and the management of data developed through these preclinical studies and clinical trials than would be the case if we were relying entirely upon our own staff. If we or any of these third parties fail to comply with applicable good laboratory practice, or good clinical practice regulations, such data may be deemed unreliable and the FDA or comparable foreign regulatory authorities may require us to perform additional preclinical or nonclinical studies, or clinical trials before approving our marketing applications. Moreover, our business may be implicated if any of these third parties violates federal or state fraud and abuse or false claims laws and regulations or healthcare privacy and security laws.

There is a limited number of third-party service providers that specialize in or have the expertise required to achieve our business objectives. If any of our relationships with these third parties terminate, we may not be able to

enter into arrangements with alternative third parties or to do so in a timely manner or on commercially reasonable terms. If the third parties do not successfully carry out their contractual duties or obligations or meet expected deadlines; if they need to be replaced; or if the quality or accuracy of the preclinical, nonclinical, or clinical data they obtain is compromised due to the failure to adhere to our preclinical or clinical protocols, regulatory requirements, or for other reasons, our preclinical studies, nonclinical studies, or clinical trials may be extended, delayed, or terminated and we may not be able to obtain regulatory approval for or successfully commercialize our product candidate(s).

We may not realize the benefits of any future collaborative or licensing arrangement, and if we fail to enter into new strategic relationships our business, financial condition, commercialization prospects, and results of operations may be materially and adversely affected.

We have in the past entered into, and may decide in the future to enter into, collaborations with pharmaceutical or biopharmaceutical companies for the development and potential commercialization of our product candidate(s). We cannot be certain that, following a strategic transaction or license, we will achieve the results, revenue, or specific net income that justifies such transaction. We may not be able to control the amount and timing of resources that is required of us to complete our development obligations or that the collaboration partner devotes to the product development or marketing programs. We also may not be able to ensure that our collaboration partner adequately protects and does not misuse our intellectual property. We and our future collaboration partner may disagree regarding the research plan or the development plan for product candidate(s) on which we are collaborating and disputes could arise between the collaborators and us that result in the delay or termination of the research, development or commercialization of our product candidate(s) or that result in costly litigation or arbitration that diverts management attention and resources. If our strategic collaborations do not result in the successful development and commercialization of product candidate(s) or if one of our collaborators fails to act under the collaboration agreement or terminates its agreement with us, we may not receive any future research funding or milestone or royalty payments under the collaboration. In addition, if a collaboration is terminated, it may result in a need for additional capital to pursue further development or commercialization of the applicable product candidate(s). If we license products or businesses, we may not be able to realize the benefit of such transactions if we are unable to successfully integrate such products or business into our existing operations and company culture.

If we are unable to obtain sufficient raw and intermediate materials on a timely basis or if we experience other supply difficulties, our business may be materially and adversely affected.

We work closely with our suppliers to ensure the continuity of supply of raw and intermediate materials but cannot guarantee these efforts will always be successful. We have experienced, and may continue to experience in the future, raw and intermediate materials supply shortages, which has contributed to manufacturing delays and impacted the progress of our clinical trials. Further, while we work to diversify our sources of raw and intermediate materials, in certain instances we acquire raw and intermediate materials from a sole supplier, and there can be no assurance that we will be able to quickly establish additional or replacement sources for some materials. A reduction or interruption in supply, and an inability to develop alternative sources for such supply, could adversely affect our ability to manufacture our product candidate(s) in a timely or cost-effective manner and could delay completion of our early-stage clinical trials, product testing, and potential regulatory approval of our product candidate(s).

Risks Related to Intellectual Property and Information Technology

Our success depends upon our ability to obtain and maintain patents and other intellectual property rights to protect our technology, including SL-325, methods used to manufacture those product candidate(s), formulations thereof, and the methods for treating patients using those product candidate(s).

The prosecution, enforcement, defense, and maintenance of intellectual property rights is often challenging, costly, and uncertain. Contributors to these challenges and uncertainty include the early stage of our products and our intellectual property portfolio development; the unpredictability of what patent claim scope will ultimately be issued to protect our products and how the law will change or develop as to scope, length, and enforcement of patent protection; the competitive and crowded inflammatory and autoimmune space; complicated and unforgiving procedural, documentary, and fee requirements of the U.S. PTO, and foreign patent offices; lack of perfect visibility into what our competitors are doing and the patent claim scope they are obtaining; lack of perfect ability to determine what prior art may exist; and the expense and time consuming nature of patent portfolio development

across relevant jurisdictions. For at least these reasons, the issuance, scope, validity, enforceability, and commercial value of our current or future patent rights are highly uncertain. We cannot be sure that patent coverage will issue, or will be maintained, to protect our products in some or all relevant jurisdictions. We cannot be sure that we will not encounter freedom-to-operate challenges in the development and commercialization of our product candidate(s). We cannot be sure our trademarks and trade names are sufficient to build name recognition in our markets of interest. We cannot be sure our measures to protect our trade secrets will be sufficient. Failure to protect or enforce these rights adequately could harm our ability to develop and market our product candidate(s) and could impair our business.

Others may challenge our patents or other intellectual property as invalid or unenforceable.

Our patent applications cannot be enforced against third parties practicing the technology claimed in such applications unless and until a patent issues from such applications, and then only to the extent the issued claims cover the technology. Given the amount of time required for the development, testing and regulatory review of new product candidates, patents protecting such candidates might expire before or shortly after such candidates are commercialized. As a result, our intellectual property may not provide us with sufficient rights to exclude others from commercializing products similar or identical to ours. Even if patents do successfully issue and even if such patents cover our product candidate(s) and extend for a commercially-relevant time, third parties may initiate invalidity, non-infringement, opposition, interference, re-examination, post-grant review, inter partes review, nullification, or derivation actions in court, before patent offices, or similar proceedings challenging the validity, inventorship, ownership, enforceability, or scope of such patents, which may result in the patent claims being narrowed, invalidated, held unenforceable, or circumvented. Such challenges and potential negative results could materially and adversely affect our business.

Furthermore, even where we have a valid and enforceable patent, we may not be able to exclude others from practicing our invention, such as where the other party can show that they used the invention in commerce before our filing date or the other party benefits from a compulsory license. Additionally, some countries, including China and India, have compulsory licensing laws under which a patent owner may be compelled to grant licenses to third parties; and some countries limit the enforceability of patents against government agencies or government contractors. In these countries, the patent owner may have limited remedies, which could materially diminish the value of such patent. Additionally, our competitors or other third parties may be able to evade our patent rights by developing new fusion proteins, antibodies, biosimilar antibodies, or alternative technologies or products in a non-infringing manner. These risks may impact our ability to enjoy the protection we obtain, and may materially and adversely impact our business.

Our commercial success depends, in part, on our ability to develop, manufacture, market, and sell our product candidate(s) without infringing or otherwise violating the intellectual property and other proprietary rights of third parties.

Others may accuse us of infringing their intellectual property. Contested proceedings are lengthy, time consuming, and costly, and we cannot guarantee that our operations and activities do not, or will not in the future, infringe existing or future patents. We also cannot guarantee that any of our patent searches or analyses, including the identification of relevant patents, the scope of patent claims, or the expiration of relevant patents, are complete or thorough, nor can we be certain that we have identified each and every third-party patent and pending application in the United States and abroad that is relevant to our product candidate(s) or necessary for the commercialization of our product candidate(s) in any jurisdiction. Furthermore, we may be subject to third-party claims asserting that our employees, consultants, contractors, collaborators, or advisors have misappropriated or wrongfully used or disseminated their intellectual property, or claiming ownership of what we regard as our own intellectual property. These and related risks to defending against third-party claims may materially and adversely affect our business.

Our competitors in both the United States and abroad, many of which have substantially greater resources and have made substantial investments in patent portfolios and competing technologies, may have applied for or obtained or may in the future apply for and obtain, patents that will prevent, limit, or otherwise interfere with our ability to make, use, and sell our product candidate(s). We do not always conduct independent reviews of pending patent applications of and patents issued to third parties. As such, there may be applications of third parties now pending or recently revived patents of which we are unaware.

Our interpretation of the relevance or the scope of a patent or a pending application may be incorrect, which may negatively impact our ability to market our product candidate(s). We may incorrectly determine that our product candidate(s) are not covered by a third-party patent or may incorrectly predict whether a third party’s pending application will issue with claims of relevant scope. Our determination of the expiration date of any patent in the United States or abroad that we consider relevant may be incorrect, which may negatively impact our ability to develop and market our product candidate(s). We cannot provide any assurances that third-party patents do not exist that might be enforced against our current technology, including our platform technologies, product candidate(s) and their respective methods of use, manufacture, and formulations thereof, and could result in either an injunction prohibiting our manufacture, future sales, or, with respect to our future sales, an obligation on our part to pay royalties and/or other forms of compensation to third parties, which could be significant.

We rely, in part, on in-licensed patents and other intellectual property rights to develop and commercialize our product candidate(s). We may need to obtain additional licenses of third-party technology that may not be available to us or are available only on commercially unreasonable terms, and which may cause us to operate our business in a more costly or otherwise adverse manner that was not anticipated.

Our competitive position may suffer if patents issued to third parties or other third-party intellectual property rights cover our methods or product candidate(s) or elements thereof, our manufacture or uses relevant to our development plans, our product candidate(s) or other attributes of our product candidate(s), or our compounds, including SL-325. In such cases, we may not be in a position to develop or commercialize product candidate(s) unless we successfully pursue litigation to nullify or invalidate the third-party intellectual property right concerned, which can be expensive and time-consuming, or we may have to enter into a license agreement with the intellectual property right holder, which may not be available on commercially reasonable terms, if at all.

There is a substantial amount of intellectual property litigation in the biotechnology and pharmaceutical industries, and we may become party to, or threatened with, litigation or other adversarial proceedings regarding intellectual property rights with respect to our product candidate(s). Parties making claims against us may seek and obtain injunctive or other equitable relief, which could effectively block our ability to further develop and commercialize our product candidate(s). The target of our product candidate(s) has also been the subject of research by many companies that have filed patent applications or have patents related to such target and therapeutics methods related to that target.

Disputes may arise with our licensors of patents and other intellectual property rights. We may yet need to obtain licenses from others for continued development and commercialization of our product candidate(s), and we may be unable to secure those licenses on commercially reasonable terms or at all. Should we be required to obtain licenses to any third-party technology, including any such patents required to manufacture, use, or sell our product candidate(s), the growth of our business will likely depend in part on our ability to acquire, in-license, maintain, or use these proprietary rights. The inability to obtain any third-party license required to develop or commercialize any of our product candidate(s) could cause us to abandon any related efforts, which could seriously harm our business and operations.

In addition, companies that perceive us to be a competitor may be unwilling to assign or license rights to us. We also may be unable to license or acquire third-party intellectual property rights on terms that would allow us to make an appropriate return on our investment. Even if we are able to obtain a license, it may be non-exclusive, thereby giving our competitors access to the same technologies licensed to us. If we are unable to successfully obtain a license to third-party intellectual property rights necessary for the development of a product candidate or program, we may have to abandon development of that product candidate or program and our business and financial condition could suffer. All licenses impose obligations upon us that must be met to maintain the license. If we are unable to meet these obligations, we may be required to pay damages and our licensors may be able to license their rights to other third parties, including our competitors, and our competitors could market competing products and technology. In addition, we and/or our licensors must cooperate in order to enforce such patents against third parties, and such cooperation may not be provided. We also may rely on our licensors to file and prosecute patent applications and maintain patents and otherwise protect the intellectual property rights we license from them and may have limited control over these activities or any other intellectual property rights that may be related to our in-licensed intellectual property rights.

In addition, our competitors may independently develop substantially equivalent trade secrets, proprietary information, or know-how and may even apply for patent protection in respect of the same. If successful in obtaining such patent protection, our competitors could limit our use of our trade secrets and/or confidential know-how. Under certain circumstances, and to make it more likely that we have our freedom to operate, we may also decide to publish some know-how to make it difficult for others to obtain patent rights covering such know-how, at the risk of potentially exposing our trade secrets to our competitors. Any of the foregoing could have a material adverse effect on our competitive position, business, financial conditions, results of operations, and prospects.

We may depend on intellectual property licensed from third parties and if we fail to comply with our obligations under any license or other agreements, we may be required to pay damages and could lose intellectual property rights that are necessary for developing and protecting our product candidate(s) or we could lose certain rights to grant sublicenses.

Our current licenses impose, and any future licenses we enter into are likely to impose, various development, commercialization, funding, milestone, royalty, diligence, sublicensing, insurance, patent prosecution and enforcement, and/or other obligations on us. If we breach any of these obligations, or use the intellectual property licensed to us in an unauthorized manner, we may be required to pay damages and the licensor may have the right to terminate the license, which could result in us being unable to develop, manufacture, and sell any future products that are covered by the licensed technology or enable a competitor to gain access to the licensed technology. Moreover, our licensors may own or control intellectual property that has not been licensed to us and, as a result, we may be subject to claims, regardless of their merit, that we are infringing or otherwise violating the licensor’s rights. In addition, while we cannot determine currently the amount of the royalty obligations we would be required to pay on sales of future products, if any, the amounts may be significant. The amount of our future royalty obligations will depend on the technology and intellectual property we use in products that we successfully develop and commercialize, if any. Therefore, even if we successfully develop and commercialize products, we may be unable to achieve or maintain profitability.

We may enjoy only limited geographical protection with respect to certain patents and may not be able to protect our intellectual property rights throughout the world.

Patents are of national or regional effect. While we will endeavor to try to protect our technologies, products and product candidates with intellectual property rights such as patents throughout the world, as appropriate, the process of obtaining patents is time-consuming, expensive, and sometimes unpredictable in other countries. In addition, differences in patent laws throughout the world may make it difficult to obtain uniform patent coverage in the jurisdictions where we have patent protection. We may not be able to file, prosecute, maintain, enforce, or license all necessary or desirable patent rights at a commercially reasonable cost or in a timely manner. In addition, we may not pursue or obtain patent protection in all markets. We have not, and will not, file for patent protection in all national and regional jurisdictions where such protection may be available. Filing, prosecuting, and defending patents on all of our research programs, compounds, and product candidates in all countries throughout the world would be prohibitively expensive, and, therefore, the scope and strength of our intellectual property rights will vary from jurisdiction to jurisdiction.

Changes in patent laws in the United States and in foreign jurisdictions could diminish the value of patents in general, thereby impairing our ability to protect our products.

Changes in either the patent laws or interpretation of the patent laws in the United States or in foreign jurisdictions could increase the uncertainties and costs surrounding the prosecution of patent applications and the enforcement or defense of issued patents. The patent laws of the U.S. and foreign jurisdictions, as well as the rules of the U.S. PTO and foreign patent offices, change from time to time. Further changes to the patent laws and/or rules of the U.S. PTO and foreign patent offices may have a significant impact on our ability to protect our technology and enforce our intellectual property rights. The Supreme Court and other federal courts also regularly rule on patent cases, including those involving the life sciences. Those decisions can change the interpretation of patent laws; for example, narrowing the scope of patent protection available in certain circumstances or weakening the rights of patent owners in certain situations. These changes to patent laws and subsequent court decisions related to patent rights have created uncertainty with respect to the value of patents once obtained. Depending on decisions by Congress, the federal courts and the U.S. PTO, and similar legislative and regulatory bodies in other countries in which we may pursue patent protection, the laws and regulations governing patents could change in unpredictable

ways that would weaken our ability to obtain new patents or to enforce our existing patents and patents that we might obtain in the future.

We may become subject to claims challenging the inventorship or ownership of our patents and other intellectual property.

We generally enter into confidentiality and intellectual property assignment agreements with our employees, consultants, and contractors. These agreements generally provide that inventions conceived by the party in the course of rendering services to us will be our exclusive property. However, those agreements may not be honored and may not effectively assign intellectual property rights to us. Moreover, there may be some circumstances where we are unable to negotiate for such ownership rights. Disputes regarding ownership or inventorship of intellectual property can also arise in other contexts, such as collaborations and sponsored research. If we are subject to a dispute challenging our rights in or to patents or other intellectual property, such a dispute could be expensive and time consuming. If we were unsuccessful, we could lose valuable rights in intellectual property that we regard as our own.

Intellectual property rights do not necessarily address all potential threats to our competitive advantage.

The degree of future protection afforded by our intellectual property rights is uncertain because intellectual property rights have limitations, and may not adequately protect our business, or permit us to maintain our competitive advantage. Moreover, if a third party has intellectual property rights that cover the practice of our technology, we may not be able to fully exercise or extract value from our intellectual property rights. The following examples are illustrative:

•others may be able to make product candidates similar to our product candidate(s) but that are not covered by the claims of the patents that we own or have exclusively licensed;

•the patents of third parties may have a material and adverse effect on our business;

•we or any future strategic partners might not have been the first to conceive or reduce to practice the inventions covered by the issued patent or pending patent application that we own or have exclusively licensed;

•we or any future strategic partners might not have been the first to file patent applications covering certain of our inventions;

•others may independently develop similar or alternative technologies or duplicate any of our technologies without infringing, misappropriating, or otherwise violating our intellectual property rights;

•our pending patent applications might not lead to issued patents;

•issued patents that we own or have exclusively licensed may not provide us with any competitive advantage, or may be held invalid or unenforceable, as a result of legal challenges by our competitors;

•we cannot predict the degree and range of protection any issued patents will afford us against competitors, whether or not others will obtain patents claiming aspects similar to those covered by our patents and patent applications, or whether we will need to initiate litigation or administrative proceedings which may be costly whether we win or lose;

•our competitors might conduct research and development activities in countries where we do not have patent rights and then use the information learned from such activities to develop competitive products for sale in our major commercial markets;

•third parties performing manufacturing or testing for us using our product candidate(s) or technologies could use the intellectual property of others without obtaining a proper license; and

•we may not develop additional technologies that are patentable.

Should any of these events occur, they could significantly harm our business, results of operations, and prospects.

We rely on trade secret and proprietary know-how, which can be difficult to trace and enforce and, if we are unable to protect the confidentiality of our trade secrets, our business and competitive position would be harmed.

Trade secrets and/or proprietary know-how can be difficult to protect or maintain as confidential. To protect this type of information against disclosure or appropriation by competitors, we generally require our employees, consultants, contractors, collaborators, advisors, and other third parties to enter into confidentiality agreements with us. Despite these efforts, any of these parties may unintentionally or willfully breach the agreements and disclose our confidential information, and confidentiality agreements may not provide an adequate remedy in the event of unauthorized disclosure of confidential information. Monitoring unauthorized uses and disclosures is difficult, and we do not know whether the steps we have taken to protect our proprietary technologies will be effective. Enforcing a claim that a third party illegally obtained and is using trade secrets and/or confidential know-how is also expensive, time-consuming, and unpredictable.

The enforceability of confidentiality agreements may vary from jurisdiction to jurisdiction. The laws of some foreign countries do not protect proprietary rights to the same extent or in the same manner as the laws of the United States. As a result, we may encounter significant problems in protecting and defending our intellectual property both in the United States and abroad. Furthermore, if a competitor lawfully obtained or independently developed any of our trade secrets, we would have no right to prevent such competitor from using that technology or information to compete with us, which could harm our competitive position. Additionally, if the steps taken to maintain our trade secrets are deemed inadequate, we may have insufficient recourse against third parties for misappropriating the trade secret. In addition, some courts inside and outside the United States are less willing or are unwilling to protect trade secrets or other proprietary information.

Any sort of contested proceeding related to intellectual property, whether offensive or defensive, may cause us to incur significant expenses and would be likely to divert significant resources from our core business, including distracting our technical and management personnel from their normal responsibilities, and may impact our reputation.

There could be public announcements of the results of or developments in hearings, motions or other interim proceedings and if securities analysts or investors perceive these results or developments to be negative, it could have a material and adverse effect on the price of our common stock. Such litigation or proceedings could substantially increase our operating losses and reduce our resources available for development activities. We may not have sufficient financial or other resources to adequately conduct such litigation or proceedings. Some of our competitors may be able to sustain the costs of such litigation or proceedings more effectively than we can because of their greater financial resources. Infringement or related suits against us by others could result in damages awards against us or injunction or other equitable relief precluding continued commercialization of our products. Uncertainties resulting from the initiation and continuation of patent litigation or other proceedings could have a material adverse effect on our ability to compete in the marketplace.

Obtaining and maintaining our patent protection depends on compliance with various procedural, document submission, fee payment, and other requirements imposed by governmental patent agencies, and our patent protection could be reduced or eliminated for noncompliance with these requirements.

Periodic maintenance and annuity fees on any issued patent are due to be paid to the U.S. PTO and foreign patent agencies in several stages over the lifetime of the patent. The U.S. PTO and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment, and other similar provisions during the patent application process and in order to maintain the patent once issued. While an inadvertent lapse can, in many cases, be cured by payment of a late fee or by other means in accordance with the applicable rules, there are situations in which noncompliance can result in abandonment or lapse of the patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. Noncompliance events that could result in abandonment or lapse of a patent or patent application include failure to respond to official actions within prescribed time limits, non-payment of fees, and failure to properly legalize and submit formal documents within prescribed time limits. If we fail to maintain the patents and patent applications covering our product candidate(s) or if we otherwise allow our patents or patent applications to be abandoned or lapse, our competitors might be able to enter the market, which would have a material and adverse effect on our business.

Our information technology systems, or those used by our CROs or other contractors or consultants, may fail or suffer security breaches, which could materially and adversely affect our business.

In the ordinary course of our business, we collect, store, and transmit large amounts of confidential information in digital form. Despite the implementation of security measures, our information technology systems and data, and those of our current or future CROs or other contractors and consultants, are vulnerable to compromise or damage from computer hacking, malicious software, fraudulent activity, employee misconduct, human error, telecommunication and electrical failures, natural disasters, or other cybersecurity attacks or accidents. While we continue to make investments to improve the protection of data and information technology, there can be no assurance that our efforts will prevent service interruptions or security breaches. Although, to our knowledge, we have not experienced any material cybersecurity incident to date, if such an event were to occur, it could seriously harm our development programs and our business operations or subject us to litigation or regulatory actions taken by governmental authorities. See Part I, Item 1. “Business-Government Regulation-Data Privacy and Security” and Part I, item 1C. “Cybersecurity” in our Annual Report on Form 10-K. Further, a cybersecurity incident may disrupt our business or damage our reputation, which could have a material adverse effect on our business, prospects, operating results, share price, stockholder value, and financial condition. We could also incur substantial remediation costs, including the costs of investigating the incident, repairing or replacing damaged systems, restoring normal business operations, implementing increased cybersecurity protections, and paying increased insurance premiums.

In addition, because we collect, store and transmit confidential information in digital form, we, and third parties who we work with, are or may become subject to numerous domestic and foreign laws, regulations, and standards relating to privacy, data protection, and data security, the scope of which is changing, subject to differing applications and interpretations, and may be inconsistent among countries, or conflict with other rules. We are or may become subject to the terms of contractual obligations related to privacy, data protection, and data security. Our obligations may also change or expand as our business grows. The actual or perceived failure by us or third parties related to us to comply with such laws, regulations and obligations could increase our compliance and operational costs, expose us to regulatory scrutiny, actions, fines and penalties, result in reputational harm, lead to a loss of customers, result in litigation and liability, and otherwise cause a material adverse effect on our business, financial condition, and results of operations. See the section titled “Business-Government Regulation-Data Privacy and Security” in our Annual Report on Form 10-K for a more detailed description of the laws that may affect our ability to operate.

Risks Related to Ownership of Our Common Stock

Our stock price may be volatile or may decline regardless of our operating performance, resulting in substantial losses for investors.

The market price of our common stock may be highly volatile and may fluctuate significantly as a result of a variety of factors, some of which are related in complex ways and many of which are beyond our control, including the factors described in this “Risk Factors” section and elsewhere in this Quarterly Report on Form 10-Q. In addition, the stock market in general, and The Nasdaq Stock Market and biopharmaceutical companies in particular, have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies. Broad market and industry factors may negatively affect the market price of our common stock, regardless of our actual operating performance. Securities class action litigation has often been instituted against companies following periods of volatility in the market price of a company’s securities. We have in the past been subject to securities class action litigation following periods of volatility in the market price of our securities. While this litigation was settled, if any similar litigation was instituted in the future, it could result in substantial costs and a diversion of management’s attention and resources, which would harm our business, operating results, or financial condition. See the discussion of Legal Proceedings in Part II, Item 1 of this Form 10-Q.

Our principal stockholders and management own a significant percentage of our stock and are able to exert significant control over matters subject to stockholder approval.

As of November 14th, 2024, our executive officers, directors, holders of 5% or more of our capital stock and their respective affiliates beneficially owned a significant percentage of our outstanding common stock. Therefore, these stockholders have the ability to influence us through this ownership position and may be able to determine all

matters requiring stockholder approval. For example, these stockholders may be able to control elections of directors, amendments of our organizational documents, or approval of any merger, sale of assets, or other major corporate transaction. This may prevent or discourage unsolicited acquisition proposals or offers for our common stock that you may feel are in your best interest as one of our stockholders.

A sale of a substantial number of shares of our common stock may cause the price of our common stock to decline.

We cannot predict what effect, if any, sales of our shares in the public market or the availability of shares for sale will have on the market price of our common stock. However, future sales of substantial amounts of our common stock in the public market, including shares sold through our ATM Facility or shares issued upon exercise of outstanding options or warrants, or the perception that such sales may occur, could adversely affect the market price of our common stock. We also expect that significant additional capital may be needed in the future to continue our planned operations. To raise capital, we may sell common stock, convertible securities, or other equity securities in one or more transactions at prices and in a manner we determine from time to time. These sales, or the perception in the market that the holders of a large number of shares intend to sell shares, could reduce the market price of our common stock.

Because we do not anticipate paying any dividends on our capital stock in the foreseeable future, capital appreciation, if any, will be your sole source of gain.

We have never declared or paid dividends on our capital stock. We currently intend to retain all of our future earnings, if any, to finance the growth and development, operation and expansion of our business and do not anticipate declaring or paying any dividends for the foreseeable future. As a result, capital appreciation, if any, of our common stock will be your sole source of gain for the foreseeable future.

General Risk Factors

Our business could be adversely affected by economic downturns, inflation, fluctuating interest rates, natural disasters, public health crises, such as pandemics, political crises, geopolitical events, or other macroeconomic conditions, which could have a material and adverse effect on our results of operations and financial condition.

The global economy, including credit and financial markets, has experienced extreme volatility and disruptions, including, among other things, diminished liquidity and credit availability, declines in consumer confidence, declines in economic growth, supply chain shortages, increases in inflation rates, fluctuating interest rates, and uncertainty about economic stability. For example, fluctuating interest rates, coupled with reduced government spending and volatility in financial markets, may increase economic uncertainty and affect consumer spending, and ongoing military conflicts throughout the world have created extreme volatility in the global capital markets and may have further global economic consequences, including disruptions of the global supply chain. Any such volatility and disruptions may adversely affect our business or the third parties on whom we rely. If the equity and credit markets deteriorate, including as a result of political unrest or war, it may make any necessary debt or equity financing more costly, more dilutive, or more difficult to obtain in a timely manner or on favorable terms, if at all. Increased inflation rates can adversely affect us by increasing our costs, including labor and employee benefit costs.

We have experienced and may in the future experience disruptions as a result of such macroeconomic conditions, including delays or difficulties in initiating or expanding clinical trials and manufacturing sufficient quantities of materials. Any one or a combination of these events could have a material and adverse effect on our results of operations and financial condition.

Adverse developments affecting the financial services industry, including events or concerns involving liquidity, defaults or non-performance by financial institutions or transactional counterparties, could adversely affect our business, financial condition or results of operations.

Our cash held in non-interest-bearing and interest-bearing accounts exceeds the Federal Deposit Insurance Corporation (“FDIC”) insurance limits. If such banking institutions were to fail, we could lose all or a portion of those amounts held in excess of such insurance limitations. The FDIC may not make all account holders whole in the event of bank failures. In addition, even if account holders are ultimately made whole with respect to a future bank failure, account holders’ access to their accounts and assets held in their accounts may be substantially delayed.

Any material loss that we may experience in the future or inability for a material time period to access our cash and cash equivalents could have an adverse effect on our ability to pay our operational expenses or make other payments, which could adversely affect our business.

If securities or industry analysts either do not publish research about us or publish inaccurate or unfavorable research about us, our business or our market, or if they change their recommendations regarding our common stock adversely, the trading price or trading volume of our common stock could decline.

The trading market for our common stock depends in part upon research and reports that securities or industry analysts may publish about us, our business, our market, or our competitors. As we have experienced in the past, if any analyst who may cover us in the future were to cease coverage of us or fail to regularly publish reports on us, we could lose visibility in the financial markets, which in turn could cause the trading price or trading volume of our common stock to decline. In addition, the price of our common stock could decline if one or more analysts downgrade our stock or issue inaccurate or other unfavorable commentary or research.

The requirements of being a public company may strain our resources, result in litigation, and divert management’s attention.

As a public company, we are subject to certain reporting requirements, listing requirements, and other applicable securities rules and regulations. Complying with these rules and regulations has increased and will continue to increase our legal and financial compliance costs, make some activities more difficult, time consuming or costly and increase demand on our systems and resources. As a result, management’s attention may be diverted from other business concerns, which could materially and adversely affect our business and operating results. In addition, a change in our filer status could trigger a requirement to begin complying with Section 404(b) of the Sarbanes-Oxley Act of 2002, and our independent registered public accounting firm would have to evaluate and report on the effectiveness of internal control over financial reporting, increasing our costs. We may also need to hire additional employees or engage outside consultants to comply with these requirements, which will increase our costs and expenses.

By disclosing information in this and in future filings required of a public company, our business and financial condition will become more visible, which has resulted in, and may in the future result in, threatened or actual litigation, including by competitors and other third parties. If those claims are successful, our business could be seriously harmed. Even if the claims do not result in litigation or are resolved in our favor, the time and resources needed to resolve them could divert our management’s resources and seriously harm our business.

Litigation filed against us could harm our business, and insurance coverage may not be sufficient to cover all related costs and damages.

We face the threat of legal claims and regulatory matters involving various aspects of our business. Given the volatility of the trading price of our common stock, and the prevalence of shareholder litigation generally, we face a risk of lawsuits alleging violations of the securities laws. Litigation is inherently uncertain, and adverse rulings may occur, including awards of monetary damages, that may have a material adverse impact on our business. These lawsuits may also divert management’s attention and resources, and may require us to incur substantial costs, some of which will not be covered by insurance.

We may become exposed to costly and damaging liability claims, either when testing a product candidate(s) in the clinic or at the commercial stage, and our product liability insurance may not cover all damages from such claims.

We are exposed to potential product liability and professional indemnity risks that are inherent in the research, development, manufacturing, marketing, and use of pharmaceutical products. While we currently have no products that have been approved for commercial sale, the future use of a product candidate(s) in clinical trials, and the sale of any approved products in the future, may expose us to liability claims. These claims may be made by patients that use the product, healthcare providers, pharmaceutical companies, or others selling such products. Any claims against us, regardless of their merit, could be difficult and costly to defend and could materially and adversely affect the market for our product candidate(s) or any prospects for commercialization of our product candidate(s). Although we currently maintain adequate product liability insurance for our product candidate(s), it is possible that any liabilities could exceed our insurance coverage or that in the future we may not be able to maintain

insurance coverage at a reasonable cost or obtain insurance coverage that will be adequate to satisfy any liability that may arise. If a successful product liability claim or series of claims is brought against us for uninsured liabilities or in excess of insured liabilities, our assets may not be sufficient to cover such claims and our business operations could be impaired.

If we fail to maintain proper and effective internal controls over financial reporting our ability to produce accurate and timely financial statements could be impaired.

We are required to report upon the effectiveness of our internal control over financial reporting. To comply with the requirements of being a reporting company under the Exchange Act, we have implemented and will continue to implement additional financial and management controls, reporting systems, and procedures and we have hired and will continue to hire additional accounting and finance staff. We cannot assure you that there will not be material weaknesses or significant deficiencies in our internal control over financial reporting in the future.

Our disclosure controls and procedures may not prevent or detect all errors or acts of fraud.

We are subject to the periodic reporting requirements of the Exchange Act. We have designed our disclosure controls and procedures to reasonably assure that information we must disclose in reports we file or submit under the Exchange Act is accumulated and communicated to management, and recorded, processed, summarized, and reported within the time periods specified in the rules and forms of the SEC. We believe that any disclosure controls and procedures or internal controls and procedures, no matter how well-conceived and operated, can provide only reasonable, not absolute, assurance that the objectives of the control system are met. These inherent limitations include the realities that judgments in decision-making can be faulty, and that breakdowns can occur because of simple error or mistake. For example, our directors or executive officers could inadvertently fail to disclose a new relationship or arrangement causing us to fail to make a required related party transaction disclosure. Additionally, controls can be circumvented by the individual acts of some persons, by collusion of two or more people, or by an unauthorized override of the controls. Accordingly, because of the inherent limitations in our control system, misstatements due to error or fraud may occur and not be detected.

Provisions in our amended and restated certificate of incorporation and our amended and restated bylaws and Delaware law might discourage, delay, or prevent a change in control of our company or changes in our management and, therefore, depress the market price of our common stock.

Our amended and restated certificate of incorporation and our amended and restated bylaws each contain provisions that could depress the market price of our common stock by acting to discourage, delay, or prevent a change in control of the Company or changes in our management that the stockholders of the Company may deem advantageous. As a Delaware corporation, we are subject to the anti-takeover provisions of Section 203 of the Delaware General Corporation Law, which prohibits a Delaware corporation from engaging in a business combination specified in the statute with an interested stockholder (as defined in the statute) for a period of three years after the date of the transaction in which the person first becomes an interested stockholder, unless the business combination is approved in advance by a majority of the independent directors or by the holders of at least two-thirds of the outstanding disinterested shares. The application of Section 203 of the Delaware General Corporation Law could also have the effect of delaying or preventing a change of control of the Company.

Our amended and restated certificate of incorporation provides that the Court of Chancery of the State of Delaware will be the exclusive forum for substantially all disputes between us and our stockholders, which could limit our stockholders’ ability to obtain a favorable judicial forum for disputes.

Our amended and restated certificate of incorporation provides that the Court of Chancery of the State of Delaware (or another state court or the federal court located within the State of Delaware if the Court of Chancery does not have or declines to accept jurisdiction) is the exclusive forum for certain actions. It also provides that the federal district courts of the United States will be the exclusive forum for resolving any complaint asserting a cause of action arising under the Securities Act but that the forum selection provision will not apply to claims brought to enforce a duty or liability created by the Exchange Act. These exclusive forum provisions may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes, which may discourage lawsuits. In addition, there is uncertainty as to whether a court would enforce such provisions. If a court were to find these types of provisions to be inapplicable or unenforceable, and if a court were to find the exclusive forum provision in our amended and restated certificate of incorporation to be inapplicable or unenforceable in an action, we may incur

additional costs associated with resolving the dispute in other jurisdictions, which could materially and adversely affect our business.

Our ability to use our net operating loss carryforwards and other tax attributes may be limited.

As of December 31, 2023, we had U.S. federal and state net operating loss (“NOL”), carryforwards of $149.5 million, which may be available to offset future taxable income. As of December 31, 2023, we also had gross federal tax credits of $16.9 million, which may be used to offset future tax liabilities. These NOLs and tax credit carryforwards will begin to expire in 2024. Use of our NOL carryforwards and tax credit carryforwards depends on many factors, including having current or future taxable income, which cannot be assured.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds

None.

Item 3. Defaults Upon Senior Securities

None.

Item 4. Mine Safety Disclosures

Not Applicable.

Item 5. Other Information

During the three months ended September 30, 2024, none of the Company’s directors or executive officers adopted, modified or terminated any contract, instruction or written plan for the purchase or sale of the Company’s securities that was intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) or any “non-Rule 10b5-1 trading arrangement” as defined in Item 408(a) of Regulation S-K).

Item 6. Exhibits

The exhibits filed or furnished as part of this Quarterly Report on Form 10-Q are set forth below.


Exhibit Number						Description of Exhibit

3.1						Amended and Restated Certificate of Incorporation of Shattuck Labs, Inc. (incorporated by reference from Exhibit 3.1 to Shattuck’s Current Report on Form 8-K filed on October 14, 2020 (Commission File No. 001-39593))

3.2						Amended and Restated Bylaws of Shattuck Labs, Inc. (incorporated by reference from Exhibit 3.2 to Shattuck’s Current Report on Form 8-K filed on October 14, 2020 (Commission File No. 001-39593))

4.1						Form of common stock certificate of Shattuck (incorporated by reference from Exhibit 4.1 of Shattuck’s Amendment No. 2 to Registration Statement on Form S-1 filed on October 8, 2020 (Commission File No. 333-248918))

4.2						Second Amended and Restated Investors’ Rights Agreement, dated as of June 12, 2020, by and among Shattuck Labs, Inc. and certain of its stockholders (incorporated by reference from Exhibit 4.2 of Shattuck’s Amendment No. 2 to Registration Statement on Form S-1 filed on October 8, 2020 (Commission File No. 333-248918))

31.1*						Certification of the principal executive officer pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934

31.2*						Certification of the principal financial officer pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934

32.1* (1)						Certification of the principal executive officer and principal financial officer pursuant to 18 U.S.C. Section 1350 and Rule 13a-14(b) under the Securities Exchange Act of 1934

101.INS*						Inline XBRL Instance Document

101.SCH*						Inline XBRL Taxonomy Extension Schema Document

101.CAL*						Inline XBRL Taxonomy Extension Calculation Linkbase Document

101.DEF*						Inline XBRL Taxonomy Extension Definition

101.LAB*						Inline XBRL Taxonomy Extension Label Linkbase Document

101.PRE*						Inline XBRL Taxonomy Extension Presentation Linkbase Document

104*						The cover page for this report, formatted in Inline XBRL (included in Exhibit 101)

______________

* Filed herewith

(1) The certifications on Exhibit 32 hereto are deemed not “filed” for purposes of Section 18 of the Exchange Act or otherwise subject to the liability of that Section. Such certifications will not be deemed incorporated by reference into any filing under the Securities Act or the Exchange Act.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.


	Shattuck Labs, Inc.

Date: November 14, 2024	By:	/s/ Dr. Taylor Schreiber
		Dr. Taylor Schreiber Chief Executive Officer (principal executive officer)

Date: November 14, 2024	By:	/s/ Andrew R. Neill
		Andrew R. Neill Chief Financial Officer (principal financial and accounting officer)

Exhibit 31.1

CERTIFICATION PURSUANT TO RULES 13a-14(a) AND 15d-14(a) UNDER THE SECURITIES

EXCHANGE ACT OF 1934, AS ADOPTED PURSUANT TO

SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Taylor Schreiber, certify that:


1.			I have reviewed this Quarterly Report on Form 10-Q of Shattuck Labs, Inc.;


2.			Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;


3.			Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;


4.			The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:


			a.			Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant is made known to us by others within those entities, particularly during the period in which this report is being prepared;


			b.			Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;


			c.			Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and


			d.			Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and


5.			The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):


			a.			All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and


			b.			Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.


Date: November 14, 2024	By:	/s/ Dr. Taylor Schreiber
		Dr. Taylor Schreiber Chief Executive Officer (principal executive officer)

Exhibit 31.2

CERTIFICATION PURSUANT TO RULES 13a-14(a) AND 15d-14(a) UNDER THE SECURITIES

EXCHANGE ACT OF 1934, AS ADOPTED PURSUANT TO

SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Andrew R. Neill, certify that:


1.			I have reviewed this Quarterly Report on Form 10-Q of Shattuck Labs, Inc.;


2.			Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;


3.			Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;


4.			The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:


			a.			Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant is made known to us by others within those entities, particularly during the period in which this report is being prepared;


			b.			Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;


			c.			Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and


			d.			Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and


5.			The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):


			a.			All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and


			b.			Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.



Date: November 14, 2024	By:	/s/ Andrew R. Neill
		Andrew R. Neill Chief Financial Officer (principal financial and accounting officer)

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report on Form 10-Q of Shattuck Labs, Inc. (the “Company”) for the period ended September 30, 2024 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), each of the undersigned officers of the Company hereby certifies, pursuant to 18 U.S.C. § 1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that to the best of his knowledge:


(1)			The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and


(2)			The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.



Date: November 14, 2024	By:	/s/ Dr. Taylor Schreiber
		Dr. Taylor Schreiber
		Chief Executive Officer (principal executive officer)
Date: November 14, 2024	By:	/s/ Andrew R. Neill
		Andrew R. Neill
		Chief Financial Officer (principal financial and accounting officer)

The foregoing certification is being furnished solely to accompany the Report pursuant to 18 U.S.C. §1350, and is not being filed for purposes of Section 18 of the Securities Exchange Act of 1934, and is not to be incorporated by reference into any filing of the Company, whether made before or after the date hereof, regardless of any general incorporation language in such filing.

Note: A signed original of this written statement required by §906 has been provided to Shattuck Labs, Inc. and will be retained by Shattuck Labs, Inc. and furnished to the Securities and Exchange Commission or its staff upon request.

Cover - shares	9 Months Ended
Cover - shares	Sep. 30, 2024	Nov. 01, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	001-39593
Entity Registrant Name	Shattuck Labs, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-2575858
Entity Address, Address Line One	500 W. 5th Street
Entity Address, Address Line Two	Suite 1200
Entity Address, City or Town	Austin
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	78701
City Area Code	512
Local Phone Number	900-4690
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	STTK
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		47,739,708
Entity Central Index Key	0001680367
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 43,829	$ 125,626
Investments	46,229	4,999
Prepaid expenses and other current assets	8,682	12,595
Total current assets	98,740	143,220
Property and equipment, net	10,827	13,804
Other assets	2,153	2,540
Total assets	111,720	159,564
Current liabilities:
Accounts payable	2,927	1,587
Accrued expenses and other current liabilities	9,474	9,866
Total current liabilities	12,401	11,453
Non-current operating lease liabilities	2,742	3,406
Total liabilities	15,143	14,859
Commitments and contingencies (Note 5)
Stockholders’ equity:
Common stock, $0.0001 par value: 300,000,000 shares authorized; 47,739,708 shares issued and outstanding at September 30, 2024 and 47,260,108 shares issued and outstanding at December 31, 2023	5	5
Additional paid-in capital	459,561	451,006
Accumulated other comprehensive (loss) income	52	4
Accumulated deficit	(363,041)	(306,310)
Total stockholders’ equity	96,577	144,705
Total liabilities and stockholders’ equity	$ 111,720	$ 159,564

CONDENSED BALANCE SHEETS - Parenthetical - $ / shares	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	47,739,708	47,260,108
Common stock, shares outstanding (in shares)	47,739,708	47,260,108

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Statement [Abstract]
Revenue from Contract with Customer, Product and Service [Extensible List]	License	License	License	License
Collaboration revenue	$ 2,997	$ 686	$ 5,721	$ 943
Operating expenses:
Research and development	16,313	24,211	51,816	59,083
General and administrative	4,604	5,073	14,831	14,866
Expense from operations	20,917	29,284	66,647	73,949
Loss from operations	(17,920)	(28,598)	(60,926)	(73,006)
Other income	1,245	1,057	4,195	3,395
Net loss	(16,675)	(27,541)	(56,731)	(69,611)
Unrealized gain on investments	57	81	48	884
Comprehensive loss	$ (16,618)	$ (27,460)	$ (56,683)	$ (68,727)
Net loss per share – basic (in dollars per share)	$ (0.33)	$ (0.65)	$ (1.12)	$ (1.64)
Net loss per share – diluted (in dollars per share)	$ (0.33)	$ (0.65)	$ (1.12)	$ (1.64)
Weighted-average shares outstanding – basic (in shares)	50,833,538	42,477,642	50,730,767	42,461,644
Weighted-average shares outstanding – diluted (in shares)	50,833,538	42,477,642	50,730,767	42,461,644

CONDENSED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2022		42,390,586
Beginning balance at Dec. 31, 2022	$ 176,157	$ 5	$ 396,041	$ (877)	$ (219,012)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and purchases pursuant to employee stock purchase plan (in shares)		11,888
Exercise of stock options and purchases pursuant to employee stock purchase plan	39		39
Issuance of common stock upon settlement of restricted stock units (in shares)		73,937
Shares withheld related to net share settlement (in shares)		(16,153)
Shares withheld related to net share settlement	(39)		(39)
Stock-based compensation expense	1,683		1,683
Unrealized gain on investments	538			538
Net loss	(20,724)				(20,724)
Ending balance (in shares) at Mar. 31, 2023		42,460,258
Ending balance at Mar. 31, 2023	157,654	$ 5	397,724	(339)	(239,736)
Beginning balance (in shares) at Dec. 31, 2022		42,390,586
Beginning balance at Dec. 31, 2022	176,157	$ 5	396,041	(877)	(219,012)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain on investments	884
Net loss	(69,611)
Ending balance (in shares) at Sep. 30, 2023		42,485,485
Ending balance at Sep. 30, 2023	112,783	$ 5	401,394	7	(288,623)
Beginning balance (in shares) at Mar. 31, 2023		42,460,258
Beginning balance at Mar. 31, 2023	157,654	$ 5	397,724	(339)	(239,736)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and purchases pursuant to employee stock purchase plan (in shares)		11,077
Exercise of stock options and purchases pursuant to employee stock purchase plan	33		33
Stock-based compensation expense	1,852		1,852
Unrealized gain on investments	265			265
Net loss	(21,346)				(21,346)
Ending balance (in shares) at Jun. 30, 2023		42,471,335
Ending balance at Jun. 30, 2023	138,458	$ 5	399,609	(74)	(261,082)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and purchases pursuant to employee stock purchase plan (in shares)		11,849
Exercise of stock options and purchases pursuant to employee stock purchase plan	21		21
Issuance of common stock upon settlement of restricted stock units (in shares)		3,375
Shares withheld related to net share settlement (in shares)		(1,074)
Shares withheld related to net share settlement	0		0
Stock-based compensation expense	1,764		1,764
Unrealized gain on investments	81			81
Net loss	(27,541)				(27,541)
Ending balance (in shares) at Sep. 30, 2023		42,485,485
Ending balance at Sep. 30, 2023	112,783	$ 5	401,394	7	(288,623)
Beginning balance (in shares) at Dec. 31, 2023		47,260,108
Beginning balance at Dec. 31, 2023	144,705	$ 5	451,006	4	(306,310)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and purchases pursuant to employee stock purchase plan (in shares)		145,841
Exercise of stock options and purchases pursuant to employee stock purchase plan	609		609
Issuance of common stock upon settlement of restricted stock units (in shares)		156,803
Shares withheld related to net share settlement (in shares)		(43,533)
Shares withheld related to net share settlement	(437)		(437)
Stock-based compensation expense	2,475		2,475
Proceeds from sale of common stock	(17)		(17)
Unrealized gain on investments	(18)			(18)
Net loss	(18,504)				(18,504)
Ending balance (in shares) at Mar. 31, 2024		47,519,219
Ending balance at Mar. 31, 2024	128,813	$ 5	453,636	(14)	(324,814)
Beginning balance (in shares) at Dec. 31, 2023		47,260,108
Beginning balance at Dec. 31, 2023	144,705	$ 5	451,006	4	(306,310)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain on investments	48
Net loss	(56,731)
Ending balance (in shares) at Sep. 30, 2024		47,739,708
Ending balance at Sep. 30, 2024	96,577	$ 5	459,561	52	(363,041)
Beginning balance (in shares) at Mar. 31, 2024		47,519,219
Beginning balance at Mar. 31, 2024	128,813	$ 5	453,636	(14)	(324,814)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and purchases pursuant to employee stock purchase plan (in shares)		205,042
Exercise of stock options and purchases pursuant to employee stock purchase plan	691		691
Issuance of common stock upon settlement of restricted stock units (in shares)		3,975
Shares withheld related to net share settlement (in shares)		(967)
Shares withheld related to net share settlement	(10)		(10)
Stock-based compensation expense	2,665		2,665
Unrealized gain on investments	9			9
Net loss	(21,552)				(21,552)
Ending balance (in shares) at Jun. 30, 2024		47,727,269
Ending balance at Jun. 30, 2024	110,616	$ 5	456,982	(5)	(346,366)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and purchases pursuant to employee stock purchase plan (in shares)		10,122
Exercise of stock options and purchases pursuant to employee stock purchase plan	27		27
Issuance of common stock upon settlement of restricted stock units (in shares)		3,375
Shares withheld related to net share settlement (in shares)		(1,058)
Shares withheld related to net share settlement	(4)		(4)
Stock-based compensation expense	2,556		2,556
Proceeds from sale of common stock	0		0
Unrealized gain on investments	57			57
Net loss	(16,675)				(16,675)
Ending balance (in shares) at Sep. 30, 2024		47,739,708
Ending balance at Sep. 30, 2024	$ 96,577	$ 5	$ 459,561	$ 52	$ (363,041)

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities:
Net loss	$ (56,731)	$ (69,611)
Adjustments to reconcile net loss to net cash used in operations:
Stock-based compensation	7,696	5,299
Depreciation	2,889	3,061
Impairment loss	147	204
Non-cash operating lease expense	315	267
Net amortization of investments	(1,730)	(1,055)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	3,913	11,890
Other assets	72	129
Accounts payable	1,340	(5,154)
Accrued expenses and other current liabilities	(392)	(6,252)
Non-current operating lease liabilities	(664)	(587)
Net cash used in operating activities	(43,145)	(61,809)
Cash flows from investing activities:
Purchase of property and equipment	(59)	(390)
Maturities of investments	54,100	130,199
Purchases of investments	(93,552)	(74,801)
Net cash (used in) provided by investing activities	(39,511)	55,008
Cash flows from financing activities:
Proceeds from the exercises of stock options and purchases pursuant to employee stock purchase plan	1,327	93
Taxes paid related to net share settlement of equity awards	(451)	(39)
Proceeds from sale of common stock	(17)	0
Net cash provided by financing activities	859	54
Net decrease in cash and cash equivalents	(81,797)	(6,747)
Cash and cash equivalents, beginning of period	125,626	47,379
Cash and cash equivalents, end of period	43,829	40,632
Supplemental disclosures of non-cash financial activities:
Deferred revenue billed but not received	$ 0	$ 500

Organization and Description of Business	9 Months Ended
Organization and Description of Business	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Shattuck Labs, Inc. (the “Company”) was incorporated in 2016 in the State of Delaware and is a biotechnology company specializing in the development of potential treatments for inflammatory and immune-mediated diseases, cancer, and other therapeutic areas. Shattuck is developing a potentially first-in-class antibody for the treatment of inflammatory bowel disease ("IBD") and other inflammatory and immune-mediated diseases. Shattuck’s expertise in protein engineering and the development of novel tumor necrosis factor ("TNF") receptor agonist and antagonist therapeutics come together in its lead program, SL-325, which it believes could be a first-in-class death receptor 3 ("DR3") antagonist antibody designed to achieve a more complete blockade of the clinically validated TL1A/DR3 pathway. Liquidity The Company has incurred losses and negative cash flows from operations since inception and has an accumulated deficit of $363.0 million as of September 30, 2024. The Company anticipates incurring additional losses and negative cash flows from operations until such time, if ever, that it can generate significant sales of its product candidates currently in development, and is highly dependent on its ability to find additional sources of funding in the form of licensing of its technology, collaboration agreements and/or public and private debt and equity financings. Adequate additional funding may not be available to the Company on acceptable terms, or at all. The failure to raise funds as and when needed could have a negative impact on the Company’s financial condition and ability to pursue its clinical operations, research and development and commercialization of its product candidates. Management believes that the Company’s cash, cash equivalents and investments of $90.1 million as of September 30, 2024 are sufficient to fund projected operations of the Company for at least the next twelve months. Global Economic Considerations The global macroeconomic environment is uncertain and could be negatively affected by, among other things, increased U.S. trade tariffs and trade disputes with other countries, instability in the global capital and credit markets, supply chain weaknesses, financial institution instability, and instability in the geopolitical environment. Such challenges have caused, and may continue to cause, recession fears, high interest rates, foreign exchange volatility and inflationary pressures. At this time, the Company is unable to quantify the potential effects of this economic instability on its future operations.

Basis of Presentation and Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited interim condensed financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”).

Unaudited Interim Condensed Financial Statements

Use of Estimates

Segment Information

Fair Value of Financial Instruments

•Level 1: Observable inputs such as quoted prices in active markets for identical assets the reporting entity has the ability to access as of the measurement date;

•Level 2: Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and

•Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.

Concentration of Risk

Cash and Cash Equivalents

Investments

Impairment of Long-Lived Assets

Leases

Commitments and Contingencies

Loss contingencies considered remote are generally not disclosed unless they involve guarantees, in which case the guarantees would be disclosed.

Revenue Recognition

i.identify the contract(s) with a customer;

ii.identify the performance obligations in the contract;

iii.determine the transaction price;

iv.allocate the transaction price to the performance obligations within the contract; and

v.recognize revenue when (or as) the entity satisfies a performance obligation.

The Company’s collaboration revenue arrangements may include the following:

To date, the Company has not granted a development and commercialization license nor recognized any revenue related to sales-based royalties or milestone payments based on the level of sales.

Research and Development Costs

Net Loss Per Share

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding as they would be anti-dilutive:


	As of September 30,
	2024	2023
Stock options	6,419,787	5,357,517
Unvested restricted stock units	1,008,535	655,777
	7,428,322	6,013,294

Other Comprehensive Income (Loss)

Recently Adopted Accounting Pronouncements

Investments

9 Months Ended

Sep. 30, 2024

Investments, Debt and Equity Securities [Abstract]

Investments

The following table represents the Company’s available-for-sale investments by major security type (amounts in thousands):


	September 30, 2024
	Amortized Cost		Gross Unrealized Gain		Total Fair Value
Investments:
U.S. government securities	$	46,181	$	48	$	46,229
Cash equivalents:
U.S. government securities	8,348		4		8,352
Total level 1 debt securities	$	54,529	$	52	$	54,581


	December 31, 2023
	Amortized Cost		Gross Unrealized Gain		Total Fair Value
Investments:
U.S. government securities	$	4,998	$	1	$	4,999
Cash equivalents:
U.S. government securities	39,657		3		39,660
Total level 1 debt securities	$	44,655	$	4	$	44,659

Accrued Expenses and Other Current Liabilities

9 Months Ended

Sep. 30, 2024

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (amounts in thousands):


	September 30, 2024		December 31, 2023
Research and development contract costs	$	4,868	$	4,235
Compensation and related benefits	1,885		3,794
Customer refund	1,613		—
Operating lease liabilities	873		796
Other	235		1,041
Total accrued expenses and other current liabilities	$	9,474	$	9,866

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases The Company leases certain office space, laboratory facilities, and equipment. These leases require monthly lease payments that may be subject to annual increases throughout the lease term. Certain of these leases also include renewal options at the election of the Company to renew or extend the lease. These optional periods have not been considered in the determination of the ROU assets or lease liabilities associated with these leases as the Company did not consider it reasonably certain it would exercise the options. The Company performed evaluations of its contracts and determined it has operating leases. There have been no material changes in the Company's operating leases as compared to the operating leases disclosed in the Company's Annual Report on Form 10-K for the year ended December 31, 2023. Kopfkino License Agreement The Company is party to an Exclusive License Agreement (the “Kopfkino License Agreement”), with Kopfkino IP, LLC (“Kopfkino”). As of October 2024, the Company discontinued clinical development of its SL-172154 product candidate that was subject to the Kopfkino License Agreement. The Company retains the exclusive license, but does not have any plans for clinical development or commercialization of any products that would be subject to the Kopfkino License Agreement and, therefore, the Company does not expect to owe milestone payments or royalties under the agreement. Litigation From time to time, the Company may become involved in various legal actions arising in the ordinary course of business. As of September 30, 2024, the Company was not aware of any existing, pending, or threatened legal actions that would have a material impact on the financial position, results of operations, or cash flows of the Company. Contractual Obligations Contractual obligations represent future cash commitments and liabilities under agreements with third parties, and exclude contingent liabilities for which the Company cannot reasonably predict future payment. The Company’s contractual obligations result primarily from obligations for various CDMOs and CROs, which include potential payments that may be required under its agreements. The contracts also contain variable costs and milestones that are hard to predict, as they are based on such things as patients enrolled and clinical trial sites. The timing of payments and actual amounts paid under CDMO and CRO agreements may be different depending on the timing of receipt of goods or services or changes to agreed-upon terms or amounts for some obligations. Such agreements are cancellable upon written notice by the Company and, therefore, are not long-term liabilities.

Collaboration Agreements	9 Months Ended
Collaboration Agreements	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaboration Agreement - Related Party	Collaboration Agreements The Company recognizes revenue for collaboration agreements using a cost-based input measure. In applying the cost-based input method of revenue recognition, the Company uses actual costs incurred relative to budgeted costs expected to be incurred, and any upfront payments are deferred accordingly. Ono Pharmaceutical Co., Ltd In February 2024, the Company entered into a collaboration and license agreement (the “Ono Agreement”) with Ono, pursuant to which the parties collaborated in the research and preclinical development of certain compounds selected by Ono from the Company’s pipeline of bifunctional fusion proteins directed toward a pair of prespecified targets for potential treatment of autoimmune and inflammatory diseases. On September 30, 2024, the Company and Ono mutually agreed to terminate the Ono Agreement (the "Ono Termination Agreement"). Following the mutual termination, the Company is no longer required to satisfy any remaining performance obligations, and will not receive any future research activity reimbursements or upfront, milestone, or royalty payments from Ono. All options and licenses held by Ono under the Collaboration Agreement were terminated. The Ono Agreement was a collaborative arrangement under ASC 808 as both companies were active participants that were exposed to significant risks and rewards. However, since the units of account identified under ASC 808 followed a typical vendor/customer relationship, the Company accounted for the transaction under ASC 606. Under the Ono Agreement, the Company granted Ono an exclusive option (the “Option”) to obtain an exclusive, sublicensable license to further research, develop, manufacture and commercialize products containing the specified bifunctional fusion proteins in any therapeutic area worldwide. The Company determined that the contingent promise to provide the license upon the exercise of the Option should be accounted for as a customer option, and the $2.0 million amount allocated to that option was recognized as revenue upon the termination of the Option pursuant to the termination of the Ono Agreement. The Company identified a single performance obligation consisting of the preclinical research activities to develop certain bifunctional fusion proteins. The Company recognized revenue for the preclinical research activities as the services were performed using an inputs method. The Company recognized revenue pursuant to the Ono Agreement of $3.0 million and $5.4 million for the three and nine months ended September 30, 2024, respectively, and did not recognize any revenue pursuant to the Ono Agreement in 2023. In August of 2024 the Company received an additional prepayment of $1.6 million for services to be performed in the fourth quarter of 2024. Pursuant to the Ono Termination Agreement, this prepayment was refunded to Ono in the fourth quarter of 2024. ImmunoGen In 2022, the Company entered into the ImmunoGen Agreement, pursuant to which ImmunoGen will reimburse the Company for $2.0 million of the costs the Company incurs in the Phase 1B combination cohort evaluating SL-172154 in combination with mirvetuximab soravtansine in patients with platinum-resistant ovarian cancer. The Company dosed its first patient with mirvetuximab soravtansine in 2023 and completed all of its obligations under the ImmunoGen Agreement in the second quarter of 2024. The Company recognized revenue of $0.0 million and $0.3 million pursuant to the ImmunoGen Agreement for the three and nine months ended September 30, 2024, respectively, and $0.7 million and $0.9 million pursuant to the ImmunoGen Agreement for the three and nine months ended September 30, 2023, respectively.

Equity	9 Months Ended
Equity	Sep. 30, 2024
Equity [Abstract]
Equity	Equity The Company is authorized to issue up to 300,000,000 shares of common stock and 10,000,000 shares of preferred stock, all with a par value of $0.0001 per share. The holders of the Company’s common stock are entitled to one vote per share on all matters submitted to a vote of stockholders. The Company’s common stock is not entitled to preemptive rights, and is not subject to conversion, redemption or sinking fund provisions. Subject to preferences that may apply to any shares of preferred stock outstanding at the time, the holders of the Company’s common stock will receive ratably any dividends declared by the Company’s board of directors (the “Board”) out of funds legally available. In the event of the Company’s liquidation, dissolution or winding-up, the holders of the Company’s common stock will be entitled to share ratably in all assets remaining after payment of or provision for any liabilities. As of the periods presented, no common stock dividends had been declared by the Board. As of September 30, 2024, none of the 10,000,000 shares of preferred stock were outstanding, and the Company has no present plans to issue any shares of preferred stock. In July 2022, the Company entered into a sales agreement (the “Sales Agreement”) with Leerink Partners LLC (the “Sales Agent”), pursuant to which it may offer and sell up to $75.0 million of shares of its common stock from time to time (the “ATM Facility”). The Sales Agent is generally entitled to compensation at a commission equal to 3.0% of the aggregate gross sales price per share sold under the Sales Agreement. As of September 30, 2024, there were no sales pursuant to the ATM Facility. In December 2023, the Company sold 4,651,163 shares of common stock through an underwritten public offering, and concurrently completed a private placement of 3,100,823 pre-funded warrants. The purchase price per share of common stock was $6.45, and the purchase price per pre-funded warrant was $6.4499, which was the purchase price per share of common stock minus the $0.0001 per share exercise price of such pre-funded warrant. Each pre-funded warrant may be exercised for one share of common stock, is immediately exercisable, does not expire, and is subject to a beneficial ownership limitation of 9.99% on a post-exercise basis. As of September 30, 2024, all 3,100,823 pre-funded warrants remain outstanding.

Stock-Based Compensation

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

Stock-Based Compensation and Employee Benefit Plans

2020 Equity Incentive Plan

2020 Employee Stock Purchase Plan

Summary of Stock-Based Compensation Expense


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	1,420	$	921	$	4,131	$	2,681
General and administrative	1,136		843		3,565		2,618
Total stock-based compensation	$	2,556	$	1,764	$	7,696	$	5,299

Stock Options

The following table summarizes option activity under the 2020 Plan for the nine months ended September 30, 2024:


	Options	Weighted Average Exercise Price		Weighted Average Remaining Life (Years)
Balance at December 31, 2023	4,942,164	$	7.21	7.62
Granted	2,038,268	9.24
Exercised	(343,759)	3.75
Forfeited	(216,886)	11.54
Balance at September 30, 2024	6,419,787	$	7.89	7.64
Vested and expected to vest	6,175,278	$	7.87	7.61
Exercisable at the end of the period	3,487,703	$	7.63	6.60

Restricted Stock Units

The following table summarizes employee RSU activity for the nine months ended September 30, 2024:


	Awards	Weighted Average Grant Date Fair Value
Balance at December 31, 2023	590,403	$	4.80
Granted	638,476	10.09
Released	(164,153)	5.05
Forfeited	(56,191)	6.29
Balance at September 30, 2024	1,008,535	$	8.03

Fair Value of Stock Options and Shares Issued

•The risk-free interest rate is based on the interest rate payable on U.S. Treasury securities in effect at the time of grant for a period that is commensurate with the expected term.

•The expected dividend yield is 0% because the Company has not historically paid, and does not expect, for the foreseeable future, to pay dividends on its common stock.

The grant-date fair value of options calculated using the Black-Scholes option pricing model granted under the Company’s 2020 Plan were estimated using the following weighted-average assumptions:


	Nine Months Ended September 30,
	2024		2023
2020 Plan
Expected term - years	6.02		6.02
Expected volatility	96.1	%	84.6	%
Risk-free interest rate	4.1	%	3.6	%
Expected dividends	—		—

options calculated using the Monte Carlo option pricing model granted under the Company’s 2020 Plan were estimated using the following assumptions.


	Nine Months Ended September 30, 2023
2020 Plan
Expected term - years	4.00
Expected volatility	80.0	%
Risk-free interest rate	3.6	%
Expected dividends	—

The grant-date fair value of shares issued calculated using the Black-Scholes option pricing model under the Company’s 2020 ESPP were estimated using the following weighted-average assumptions:


	Nine Months Ended September 30,
	2024		2023
2020 ESPP
Expected term - years	0.50		0.50
Expected volatility	115.1	%	85.5	%
Risk-free interest rate	5.1	%	4.0	%
Expected dividends	—		—

Discontinuation of SL-172154 Clinical Development	9 Months Ended
Discontinuation of SL-172154 Clinical Development	Sep. 30, 2024
Restructuring and Related Activities [Abstract]
Discontinuation of SL-172154 Clinical Development	Discontinuation of SL-172154 Clinical Development On October 1, 2024, the Company approved a restructuring plan to prioritize the development of the Company’s DR3 program. The restructuring plan is intended to optimize the Company’s cost structure by aligning the size and structure of its workforce with the Company’s current goals and strategy. The organizational realignment includes discontinuing the Company’s SL-172154 program in view of overall survival data readouts from its studies in higher-risk myelodysplastic syndromes and acute myeloid leukemia. Approximately 40% of Shattuck’s workforce was impacted by the changes. The Company has substantially completed the reduction in force. As a result of these changes, the Company expects to incur restructuring charges between $1.5 million and $1.75 million, the majority of which are related to employee severance costs. The Company anticipates recognizing these expenses in the fourth quarter of 2024. Substantially all of the charges are expected to be future cash expenditures. The estimates of costs and expenses that the Company expects to incur in connection with the changes are contingent on various assumptions and actual results may differ materially. The Company may also incur additional costs not currently contemplated due to events related to or resulting from these strategic steps.

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net loss	$ (16,675)	$ (21,552)	$ (18,504)	$ (27,541)	$ (21,346)	$ (20,724)	$ (56,731)	$ (69,611)

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Unaudited Interim Condensed Financial Statements	Basis of Presentation The accompanying unaudited interim condensed financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Unaudited Interim Condensed Financial Statements In the opinion of management, the accompanying interim financial statements include all normal and recurring adjustments (which consist primarily of accruals, estimates and assumptions that impact the financial statements) considered necessary to present fairly the Company’s financial position, its results of operations, statements of changes in stockholders’ equity and cash flows for the interim periods presented. Operating results for interim periods presented are not necessarily indicative of the results that may be expected for the year ending December 31, 2024. The interim financial statements presented herein do not contain all required disclosures under GAAP for annual financial statements. The accompanying unaudited interim condensed financial statements should be read in conjunction with the annual audited financial statements and related notes in the Company's Annual Report on Form 10-K for the year ended December 31, 2023.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, revenue recognition, the accrual of research and development expenses, and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates, if any, are recorded in the period in which they become known and actual results could differ from management’s estimates.
Segment Information	Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business as one segment.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the price that would be received upon the sale of an asset or paid upon the transfer of a liability in an orderly transaction between market participants at the measurement date and in the principal or most advantageous market for that asset or liability. Fair value measurements are classified and disclosed in one of the following categories: •Level 1: Observable inputs such as quoted prices in active markets for identical assets the reporting entity has the ability to access as of the measurement date; •Level 2: Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and •Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Fair value measurements are classified based on the lowest level of input that is significant to the measurement. The Company’s assessment of the significance of a particular input to the fair value measurement requires judgment, which may affect the valuation of the assets and liabilities and their placement within the fair value hierarchy levels. The determination of the fair values takes into account the market for its financial assets and liabilities, the associated credit risk and other factors as required. The Company considers active markets as those in which transactions for the assets or liabilities occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Management believes that the carrying amounts of the Company’s financial instruments, including investments and accounts payable, approximate fair value due to the short-term nature of those instruments.
Concentration of Risk	Concentration of Risk Financial instruments that potentially subject the Company to concentrations of credit risk primarily consist of cash, cash equivalents and investments. The Company maintains its cash and cash equivalents at two accredited financial institutions in amounts that exceed federally-insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company invests in only U.S. Treasury securities that management believes protects the Company from risk of default and impairment of value. All of the Company’s revenue in 2024 has been derived from collaborations with Ono Pharmaceutical Co., Ltd (“Ono”) and ImmunoGen, Inc. ("ImmunoGen"), and revenue in 2023 was derived from a collaboration agreement with ImmunoGen (the “ImmunoGen Agreement”). In February 2024, ImmunoGen was acquired by AbbVie, Inc. The Company is highly dependent on a limited number of contract development and manufacturing organizations (“CDMOs”) to supply drug products for its research and development activities of its programs, including clinical trials and non-clinical studies. These programs could be adversely affected by a significant interruption in the supply of such drug products. The Company is highly dependent on a limited number of contract research organizations (“CROs”) and third-party service providers to manage and support its clinical trials. These programs could be adversely affected by a significant disruption in services provided by these CROs and third parties.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all demand deposits with financial institutions and all highly liquid investments with original maturities of 90 days or less at the date of purchase to be cash and cash equivalents.
Investments	Investments The Company’s investments consist of highly-rated U.S. Treasury securities and have been classified as available-for-sale and are carried at estimated fair value as determined based upon quoted market prices. Management determines the appropriate classification of its investment securities at the time of purchase. The Company may hold securities with stated maturities greater than one year. All available-for-sale securities are considered available to support current operations and are classified as current assets. Credit impairments for available-for-sale securities are recorded through an allowance rather than a direct write-down of the security and are recorded through a charge to the statements of operations. Unrealized gains or losses not related to credit impairments are recorded in accumulated other comprehensive income (loss), a component of stockholders’ equity, until realized. The Company reviews available-for-sale debt securities for impairments related to credit losses and other factors each quarter.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets are reviewed for indications of possible impairment whenever events or changes in circumstance indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amounts to the future undiscounted cash flows attributable to these assets. An impairment loss is recognized to the extent an asset group is not recoverable and the carrying amount exceeds the projected discounted future cash flows arising from these assets.
Leases	Leases The Company determines if an arrangement is a lease at inception. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The classification of the Company’s leases as operating or finance leases, along with the initial measurement and recognition of the associated ROU assets and lease liabilities, are performed at the lease commencement date. The measurement of lease liabilities is based on the present value of future lease payments over the lease term. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of future lease payments. The ROU asset is based on the measurement of the lease liability and also includes any lease payments made prior to or on lease commencement and excludes lease incentives and initial direct costs incurred, as applicable. The lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise any such options. Rent expense for the Company’s operating leases is recognized on a straight-line basis over the lease term. The Company has elected to not apply the recognition requirement of Accounting Standards Codification (“ASC”) 842, Leases of the Financial Accounting Standards Board (“FASB”) to leases with a term of 12 months or less for all classes of assets.
Commitments and Contingencies	Commitments and Contingencies The Company follows ASC 450-20, Contingencies of the FASB to report accounting for contingencies. Certain conditions may exist as of the date the condensed financial statements are issued, which may result in a loss to the Company but which will only be resolved when one or more future events occur or fail to occur. The Company assesses such contingent liabilities, and such assessment inherently involves an exercise of judgment. In assessing loss contingencies related to legal proceedings that are pending against the Company or unasserted claims that may result in such proceedings, the Company evaluates the perceived merits of any legal proceedings or unasserted claims as well as the perceived merits of the amount of relief sought or expected to be sought therein. If the assessment of a contingency indicates that it is probable that a material loss has been incurred and the amount of the liability can be estimated, then the estimated liability would be accrued in the Company’s condensed financial statements. If the assessment indicates that a potential material loss contingency is not probable but is reasonably possible, or is probable but cannot be estimated, then the nature of the contingent liability, and an estimate of the range of possible losses, if determinable and material, would be disclosed. Loss contingencies considered remote are generally not disclosed unless they involve guarantees, in which case the guarantees would be disclosed.
Revenue Recognition	Revenue Recognition Collaboration revenue is recognized in accordance with ASC 606, Revenue from Contracts with Customers (“ASC 606”). Arrangements with collaborators may include licenses to intellectual property, research and development services, manufacturing services for clinical and commercial supply and participation on joint steering committees. The Company evaluates the promised goods or services in the contract to determine which promises, or group of promises, represent performance obligations. In contemplation of whether a promised good or service meets the criteria required of a performance obligation, the Company considers the stage of development of the underlying intellectual property, the capabilities and expertise of the customer relative to the underlying intellectual property and whether the promised goods or services are integral to or dependent on other promises in the contract. When accounting for an arrangement that contains multiple performance obligations, the Company must develop judgmental assumptions, which may include market conditions, reimbursement rates for personnel costs, development timelines and probabilities of regulatory success to determine the stand-alone selling price for each performance obligation identified in the contract. Upon the amendment of an existing agreement, the Company evaluates whether the amendment represents a modification to an existing contract that would be recorded through a cumulative catch-up to revenue, or a separate contract. If it is determined that it is a separate contract, the Company will evaluate the necessary revenue recognition through the five-step process described below. When the Company concludes that a contract should be accounted for as a combined performance obligation and recognized over time, the Company must then determine the period over which revenue should be recognized and the method by which to measure revenue. The Company generally recognizes revenue using a cost-based input method. The Company recognizes collaboration revenue in an amount that reflects the consideration that the Company expects to receive in exchange for those goods or services when its customer or collaborator obtains control of promised goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the following five steps are performed: i.identify the contract(s) with a customer; ii.identify the performance obligations in the contract; iii.determine the transaction price; iv.allocate the transaction price to the performance obligations within the contract; and v.recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it determines that it is probable it will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within the contract to determine whether each promised good or service is a performance obligation. The promised goods or services in the Company’s arrangements may consist of a license of, or options to license, the Company’s intellectual property and research, development and manufacturing services. The Company may provide options to additional items in such arrangements, which are accounted for as separate contracts when the customer elects to exercise such options, unless the option provides a material right to the customer. Performance obligations are promises in a contract to transfer a distinct good or service to the customer that (i) the customer can benefit from on its own or together with other readily available resources and (ii) are separately identifiable from other promises in the contract. Goods or services that are not individually distinct performance obligations are combined with other promised goods or services until such combined group of promises meet the requirements of a performance obligation. The Company determines transaction price based on the amount of consideration the Company expects to receive for transferring the promised goods or services in the contract. Consideration may be fixed, variable or a combination of both. At contract inception for arrangements that include variable consideration, the Company estimates the probability and extent of consideration it expects to receive under the contract utilizing either the most-likely amount method or expected amount method, whichever best estimates the amount expected to be received. The Company then considers any constraints on the variable consideration and includes variable consideration in the transaction price to the extent it is deemed probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. The Company then allocates the transaction price to each performance obligation based on the relative standalone selling price and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. For performance obligations that consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The Company records amounts as accounts receivable when the right to consideration is deemed unconditional. When consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract, a contract liability is recorded as deferred revenue. Amounts received prior to satisfying the revenue recognition criteria are recognized as deferred revenue in the Company’s accompanying balance sheet. Deferred revenues expected to be recognized as revenue within the 12 months following the balance sheet date are classified as a current liability. Deferred revenues not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as non-current liabilities. The Company’s collaboration revenue arrangements may include the following: Up-front License Fees: If a license is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from nonrefundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments: At the inception of an agreement that includes research and development milestone payments, the Company evaluates each milestone to determine when and how much of the milestone to include in the transaction price. The Company first estimates the amount of the milestone payment that the Company could receive using either the expected value or the most-likely amount approach. The Company primarily uses the most-likely amount approach as that approach is generally most predictive for milestone payments with a binary outcome. The Company then considers whether any portion of that estimated amount is subject to the variable consideration constraint (that is, whether it is probable that a significant reversal of cumulative revenue would not occur upon resolution of the uncertainty). The Company updates the estimate of variable consideration included in the transaction price at each reporting date which includes updating the assessment of the likely amount of consideration and the application of the constraint to reflect current facts and circumstances. Royalties: For arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not granted a development and commercialization license nor recognized any revenue related to sales-based royalties or milestone payments based on the level of sales. Research and Development Services: The Company will record costs associated with development and process optimization activities as research and development expenses in the statements of operations and comprehensive loss consistent with ASC 730, Research and Development. The Company considered the guidance in ASC 808, Collaborative Arrangements ("ASC 808") and will recognize the payments received from these agreements as revenue when the related costs are incurred.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred, and include salaries, stock-based compensation and other personnel-related costs, equipment and supplies, depreciation, nonclinical studies, clinical trials and manufacturing development activities. A substantial portion of the Company’s ongoing research and development activities are conducted by third-party service providers, including CROs and CDMOs. The Company accrues for expenses resulting from obligations under agreements with CROs, CDMOs and other outside service providers for which payment flows do not match the periods over which materials or services are provided to the Company. Accruals are recorded based on estimates of services received and efforts expended pursuant to agreements established with CROs, CDMOs and other outside service providers. These estimates are typically based on contracted amounts applied to the proportion of work performed and determined through an evaluation of the progress or stage of completion of the services. In the event advance payments are made to a CRO, CDMO or outside service provider, the payments will be recorded as a prepaid asset, which will be amortized as the contracted services are performed. As actual costs become known, the Company adjusts its accruals and prepaid assets accordingly. Inputs, such as the services performed, the number of patients enrolled or the study duration, may vary from the Company’s estimates, resulting in adjustments to research and development expense in future periods. The Company makes significant judgments and estimates in determining the accrual and/or prepaid balance in each reporting period and changes in these estimates may result in material changes to the Company’s accruals that could materially affect the Company’s results of operations.
Net Loss Per Share	Net Loss Per Share Basic loss per share of common stock is computed by dividing net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during each period. Basic shares outstanding includes the weighted average effect of the Company’s outstanding 3,100,823 pre-funded warrants, the exercise of which requires nominal consideration for the delivery of shares of common stock. Diluted loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as redeemable convertible preferred stock or convertible notes, if any, stock options and unvested shares of restricted stock, which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive.
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Other comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Other comprehensive income (loss) is comprised of the net loss and unrealized gains and losses on investments.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements The Company will adopt Update 2023-07 in the period required and while it will require the Company to expand certain disclosures within the notes to its financial statements, the Company does not expect the adoption to have a material impact on the its financial position, operating results or cash flows. In November 2024, the FASB issued ASU 2024-03, Accounting Standards Update 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses to improve financial reporting by requiring that public business entities disclose additional information about specific expense categories in the notes to financial statements at interim and annual reporting periods. This ASU is effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently evaluating the impact of adopting this ASU to its notes to the consolidated financial statements and processes.

Basis of Presentation and Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of antidilutive securities excluded from computation of net loss per share

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding as they would be anti-dilutive:


	As of September 30,
	2024	2023
Stock options	6,419,787	5,357,517
Unvested restricted stock units	1,008,535	655,777
	7,428,322	6,013,294

Investments (Tables)

9 Months Ended

Sep. 30, 2024

Investments, Debt and Equity Securities [Abstract]

Schedule of investments

The following table represents the Company’s available-for-sale investments by major security type (amounts in thousands):


	September 30, 2024
	Amortized Cost		Gross Unrealized Gain		Total Fair Value
Investments:
U.S. government securities	$	46,181	$	48	$	46,229
Cash equivalents:
U.S. government securities	8,348		4		8,352
Total level 1 debt securities	$	54,529	$	52	$	54,581


	December 31, 2023
	Amortized Cost		Gross Unrealized Gain		Total Fair Value
Investments:
U.S. government securities	$	4,998	$	1	$	4,999
Cash equivalents:
U.S. government securities	39,657		3		39,660
Total level 1 debt securities	$	44,655	$	4	$	44,659

Accrued Expenses and Other Current Liabilities (Tables)

9 Months Ended

Sep. 30, 2024

Payables and Accruals [Abstract]

Schedule of accrued expenses and other current liabilities

Accrued expenses and other current liabilities consisted of the following (amounts in thousands):


	September 30, 2024		December 31, 2023
Research and development contract costs	$	4,868	$	4,235
Compensation and related benefits	1,885		3,794
Customer refund	1,613		—
Operating lease liabilities	873		796
Other	235		1,041
Total accrued expenses and other current liabilities	$	9,474	$	9,866

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Schedule of stock-based compensation expense


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	1,420	$	921	$	4,131	$	2,681
General and administrative	1,136		843		3,565		2,618
Total stock-based compensation	$	2,556	$	1,764	$	7,696	$	5,299

Schedule of option activity

The following table summarizes option activity under the 2020 Plan for the nine months ended September 30, 2024:


	Options	Weighted Average Exercise Price		Weighted Average Remaining Life (Years)
Balance at December 31, 2023	4,942,164	$	7.21	7.62
Granted	2,038,268	9.24
Exercised	(343,759)	3.75
Forfeited	(216,886)	11.54
Balance at September 30, 2024	6,419,787	$	7.89	7.64
Vested and expected to vest	6,175,278	$	7.87	7.61
Exercisable at the end of the period	3,487,703	$	7.63	6.60

Schedule of RSU activity

The following table summarizes employee RSU activity for the nine months ended September 30, 2024:


	Awards	Weighted Average Grant Date Fair Value
Balance at December 31, 2023	590,403	$	4.80
Granted	638,476	10.09
Released	(164,153)	5.05
Forfeited	(56,191)	6.29
Balance at September 30, 2024	1,008,535	$	8.03

Schedule of valuation assumptions

The grant-date fair value of options calculated using the Black-Scholes option pricing model granted under the Company’s 2020 Plan were estimated using the following weighted-average assumptions:


	Nine Months Ended September 30,
	2024		2023
2020 Plan
Expected term - years	6.02		6.02
Expected volatility	96.1	%	84.6	%
Risk-free interest rate	4.1	%	3.6	%
Expected dividends	—		—

options calculated using the Monte Carlo option pricing model granted under the Company’s 2020 Plan were estimated using the following assumptions.


	Nine Months Ended September 30, 2023
2020 Plan
Expected term - years	4.00
Expected volatility	80.0	%
Risk-free interest rate	3.6	%
Expected dividends	—

The grant-date fair value of shares issued calculated using the Black-Scholes option pricing model under the Company’s 2020 ESPP were estimated using the following weighted-average assumptions:


	Nine Months Ended September 30,
	2024		2023
2020 ESPP
Expected term - years	0.50		0.50
Expected volatility	115.1	%	85.5	%
Risk-free interest rate	5.1	%	4.0	%
Expected dividends	—		—

Organization and Description of Business (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ 363,041	$ 306,310
Cash, cash equivalents, and short-term investments	$ 90,100

Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($) shares	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) segment shares	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) shares
Cash and Cash Equivalents [Line Items]
Number of operating segments \| segment			1
Cash and cash equivalents	$ 43,829,000		$ 43,829,000		$ 125,626,000
Investment impairment	0	$ 0	0	$ 0
Tangible asset impairment charges	$ 100,000	$ 200,000	$ 200,000	$ 200,000
Number of securities called by warrants or rights (in shares) \| shares	3,100,823		3,100,823		3,100,823
Operating Account
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 3,100,000		$ 3,100,000		$ 4,800,000
Money Market Funds
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	32,400,000		32,400,000		81,100,000
Government Obligations
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 8,400,000		$ 8,400,000		$ 39,700,000

Basis of Presentation and Summary of Significant Accounting Policies - Schedule of anti-dilutive securities (Details) - shares	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	7,428,322	6,013,294
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	6,419,787	5,357,517
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (in shares)	1,008,535	655,777

Investments - Schedule of available for sale investments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Investments:
Amortized Cost	$ 54,529	$ 44,655
Gross Unrealized Gain	52	4
Total Fair Value	54,581	44,659
U.S. government securities \| Investments:
Investments:
Amortized Cost	46,181	4,998
Gross Unrealized Gain	48	1
Total Fair Value	46,229	4,999
U.S. government securities \| Cash equivalents:
Investments:
Amortized Cost	8,348	39,657
Gross Unrealized Gain	4	3
Total Fair Value	$ 8,352	$ 39,660

Investments - Narrative (Details)	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Debt securities, average maturity term	2 months 1 day

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Research and development contract costs	$ 4,868	$ 4,235
Compensation and related benefits	1,885	3,794
Customer refund	1,613	0
Operating lease liabilities	873	796
Other	235	1,041
Total accrued expenses and other current liabilities	$ 9,474	$ 9,866

Collaboration Agreements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Collaboration Agreements (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Aug. 31, 2024	Feb. 29, 2024	Dec. 31, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue	$ 2,997	$ 686	$ 5,721	$ 943
Ono Pharmaceutical Co. \| License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract with customer, liability					$ 1,600
Collaboration revenue	3,000		5,400
Ono Pharmaceutical Co., Option \| License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract with customer, liability						$ 2,000
ImmunoGen \| Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Remaining performance obligation, amount							$ 2,000
Collaboration revenue	$ 0	$ 700	$ 300	$ 900

Equity (Details) $ / shares in Units, $ in Millions	1 Months Ended	9 Months Ended
Equity (Details) $ / shares in Units, $ in Millions	Dec. 31, 2023 $ / shares shares	Sep. 30, 2024 vote $ / shares shares	Jul. 31, 2022 USD ($)
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Preferred stock, shares authorized (in shares)		10,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001
Preferred stock, par value (in dollars per share) \| $ / shares		$ 0.0001
Common stock, number of votes per common share \| vote		1
Preferred stock, shares outstanding (in shares)		0
Stock issued during period, new issues (in shares)	4,651,163
Number of securities called by warrants or rights (in shares)	3,100,823	3,100,823
Sale of preferred stock (in dollars per share) \| $ / shares	$ 6.45
Price of pre-funded warrants (in dollars per share) \| $ / shares	6.4499
Exercise price of warrants or rights (in dollars per share) \| $ / shares	$ 0.0001
Number of securities called by each warrant or right (in share per share)	1
Pre-funded warrants, ownership limitation post-exercise	0.0999
Class of warrant or right, outstanding (in shares)		3,100,823
Private Placement
Class of Stock [Line Items]
Sale of stock maximum aggregate sales price \| $			$ 75.0
Sale of stock commission			3.00%
Preferred stock sold (in shares)		0

Stock-Based Compensation - Narrative (Details) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 01, 2024 shares	Oct. 31, 2020 USD ($) shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2024 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value (in dollars per share) \| $ / shares					$ 7.29	$ 2.50
Unrecognized compensation cost			$ 17,000		$ 17,000
Intrinsic value of options exercised					1,900	$ 0
Aggregate intrinsic value of options exercisable			800		800
Aggregate intrinsic value of options outstanding			800		800
Total stock-based compensation			2,556	$ 1,764	$ 7,696	5,299
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average amortization period					2 years 5 months 20 days
Expected dividends					0.00%
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average amortization period					2 years 9 months 18 days
Total stock-based compensation					$ 1,600	$ 700
Unrecognized compensation cost for RSU			$ 5,600		$ 5,600
2020 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares authorized, percentage of capital stock outstanding							0.04
Common stock, additional capital shares reserved for future issuance (in shares) \| shares	1,890,404
Shares reserved for future issuance (in shares) \| shares			3,516,051		3,516,051
Stock-based compensation, vesting period					4 years
Share-based compensation, expiration period					10 years
2020 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares authorized, percentage of capital stock outstanding		0.01
Common stock, additional capital shares reserved for future issuance (in shares) \| shares	472,601
Shares reserved for future issuance (in shares) \| shares			1,660,229		1,660,229
Purchase price of common stock in percent		85.00%
Contribution limit in percentage of employee's eligible compensation		15.00%
Maximum value of shares per employee during any calendar year		$ 25
Maximum number of shares per employee during any one purchase period (in shares) \| shares		600
Annual increase in number of shares authorized, term					10 years
Stock issued under ESPP (in shares) \| shares			9,960	11,849	17,246	23,020
Proceeds from ESPP			$ 100	$ 100	$ 100	$ 100

Stock-Based Compensation - Schedule of stock-based compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 2,556	$ 1,764	$ 7,696	$ 5,299
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	1,420	921	4,131	2,681
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 1,136	$ 843	$ 3,565	$ 2,618

Stock-Based Compensation - Schedule of option activity (Details) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Options
Beginning balance (in shares)	4,942,164
Granted (in shares)	2,038,268
Exercised (in shares)	(343,759)
Forfeited (in shares)	(216,886)
Ending balance (in shares)	6,419,787	4,942,164
Vested and expected to vest (in shares)	6,175,278
Exercisable (in shares)	3,487,703
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 7.21
Granted (in dollars per share)	9.24
Exercised (in dollars per share)	3.75
Forfeited (in dollars per share)	11.54
Ending balance (in dollars per share)	7.89	$ 7.21
Vested and expected to vest (in dollars per share)	7.87
Exercisable (in dollars per share)	$ 7.63
Weighted Average Remaining Life (Years)
Outstanding	7 years 7 months 20 days	7 years 7 months 13 days
Vested and expected to vest	7 years 7 months 9 days
Exercisable	6 years 7 months 6 days

Stock-Based Compensation - Schedule of restricted stock activity (Details) - Restricted Stock Units (RSUs)	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Awards
Awards, beginning balance (in shares) \| shares	590,403
Granted (in shares) \| shares	638,476
Released (in shares) \| shares	(164,153)
Forfeited (in shares) \| shares	(56,191)
Awards, ending balance (in shares) \| shares	1,008,535
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share) \| $ / shares	$ 4.80
Granted (in dollars per share) \| $ / shares	10.09
Released (in dollars per share) \| $ / shares	5.05
Forfeited (in dollars per share) \| $ / shares	6.29
Ending balance (in dollars per share) \| $ / shares	$ 8.03

Stock-Based Compensation - Schedule of valuation assumptions (Details)	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividends	0.00%
Stock options \| 2020 Stock Incentive Plan \| Black-Scholes Option Pricing Model
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term - years	6 years 7 days	6 years 7 days
Expected volatility	96.10%	84.60%
Risk-free interest rate	4.10%	3.60%
Expected dividends	0.00%	0.00%
Stock options \| 2020 Stock Incentive Plan \| Monte Carlo Option Pricing Model
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term - years		4 years
Expected volatility		80.00%
Risk-free interest rate		3.60%
Expected dividends		0.00%
ESPP \| 2020 Employee Stock Purchase Plan \| Black-Scholes Option Pricing Model
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term - years	6 months	6 months
Expected volatility	115.10%	85.50%
Risk-free interest rate	5.10%	4.00%
Expected dividends	0.00%	0.00%

Discontinuation of SL-172154 Clinical Development (Details) $ in Thousands	Aug. 01, 2024 USD ($)
Minimum
Restructuring Cost and Reserve [Line Items]
Expected cost	$ 1,500
Maximum
Restructuring Cost and Reserve [Line Items]
Expected cost	$ 1,750

Shattuck Labs (NASDAQ:STTK)
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