MBX MBX Biosciences Inc

The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

 Name of Reporting Persons.

 Frazier Life Sciences Public Fund, L.P.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 WC

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 1,103,920 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 1,103,920 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 1,103,920 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 3.5% (2)

 Type of Reporting Person (See Instructions)

 PN

Consists of 1,103,920 shares of Common Stock held directly by Frazier Life Sciences Public Fund, L.P. FHMLSP, L.P. is the general partner of Frazier Life Sciences Public Fund, L.P. and FHMLSP, L.L.C. is the general partner of FHMLSP, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Fund, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 FHMLSP, L.P.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 1,103,920 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 1,103,920 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 1,103,920 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 3.5% (2)

 Type of Reporting Person (See Instructions)

 PN

Consists of 1,103,920 shares of Common Stock held directly by Frazier Life Sciences Public Fund, L.P. FHMLSP, L.P. is the general partner of Frazier Life Sciences Public Fund, L.P. and FHMLSP, L.L.C. is the general partner of FHMLSP, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Fund, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 FHMLSP, L.L.C.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 1,103,920 shares (1)

 Sole Dispositive Power

 0

 Shared Dispositive Power

 1,103,920 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 1,103,920 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 3.5% (2)

 Type of Reporting Person (See Instructions)

 OO

Consists of 1,103,920 shares of Common Stock held directly by Frazier Life Sciences Public Fund, L.P. FHMLSP, L.P. is the general partner of Frazier Life Sciences Public Fund, L.P. and FHMLSP, L.L.C. is the general partner of FHMLSP, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Fund, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 Frazier Life Sciences Public Overage Fund, L.P.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 WC

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 325,653 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 325,653 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 325,653 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 1.0% (2)

 Type of Reporting Person (See Instructions)

 PN

Consists of 325,653 shares of Common Stock held directly by Frazier Life Sciences Public Overage Fund, L.P. FHMLSP Overage, L.P. is the general partner of Frazier Life Sciences Public Overage Fund, L.P. and FHMLSP Overage, L.L.C. is the general partner of FHMLSP Overage, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP Overage, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Overage Fund, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 FHMLSP Overage, L.P.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 325,653 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 325,653 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 325,653 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 1.0% (2)

 Type of Reporting Person (See Instructions)

 PN

Consists of 325,653 shares of Common Stock held directly by Frazier Life Sciences Public Overage Fund, L.P. FHMLSP Overage, L.P. is the general partner of Frazier Life Sciences Public Overage Fund, L.P. and FHMLSP Overage, L.L.C. is the general partner of FHMLSP Overage, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP Overage, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Overage Fund, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 FHMLSP Overage, L.L.C.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 325,653 shares (1)

 Sole Dispositive Power

 0

 Shared Dispositive Power

 325,653 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 325,653 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 1.0% (2)

 Type of Reporting Person (See Instructions)

 OO

Consists of 325,653 shares of Common Stock held directly by Frazier Life Sciences Public Overage Fund, L.P. FHMLSP Overage, L.P. is the general partner of Frazier Life Sciences Public Overage Fund, L.P. and FHMLSP Overage, L.L.C. is the general partner of FHMLSP Overage, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP Overage, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Overage Fund, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 Frazier Life Sciences X, L.P.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 WC

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 4,552,774 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 4,552,774 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 4,552,774 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 14.3% (2)

 Type of Reporting Person (See Instructions)

 PN

Consists of 4,552,774 shares of Common Stock held directly by Frazier Life Sciences X, L.P. FHMLS X, L.P. is the general partner of Frazier Life Sciences X, L.P. and FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. Patrick J. Heron and James N. Topper are the members of FHMLS X, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences X, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 FHMLS X, L.P.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 4,552,774 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 4,552,774 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 4,552,774 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 14.3% (2)

 Type of Reporting Person (See Instructions)

 PN

Consists of 4,552,774 shares of Common Stock held directly by Frazier Life Sciences X, L.P. FHMLS X, L.P. is the general partner of Frazier Life Sciences X, L.P. and FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. Patrick J. Heron and James N. Topper are the members of FHMLS X, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences X, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 FHMLS X, L.L.C.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 4,552,774 shares (1)

 Sole Dispositive Power

 0

 Shared Dispositive Power

 4,552,774 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 4,552,774 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 14.3% (2)

 Type of Reporting Person (See Instructions)

 OO

Consists of 4,552,774 shares of Common Stock held directly by Frazier Life Sciences X, L.P. FHMLS X, L.P. is the general partner of Frazier Life Sciences X, L.P. and FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. Patrick J. Heron and James N. Topper are the members of FHMLS X, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences X, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 Frazier Life Sciences XI, L.P.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 WC

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 3,000 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 3,000 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 3,000 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 0.0% (2)

 Type of Reporting Person (See Instructions)

 PN

Consists of 3,000 shares of Common Stock held directly by Frazier Life Sciences XI, L.P. FHMLS XI, L.P. is the general partner of by Frazier Life Sciences XI, L.P. and FHMLS XI, L.L.C. is the general partner of FHMLS XI, L.P. Patrick J. Heron, James N. Topper and Daniel Estes are the members of FHMLS XI, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences XI, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 FHMLS XI, L.P.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 3,000 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 3,000 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 3,000 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 0.0% (2)

 Type of Reporting Person (See Instructions)

 PN

Consists of 3,000 shares of Common Stock held directly by Frazier Life Sciences XI, L.P. FHMLS XI, L.P. is the general partner of by Frazier Life Sciences XI, L.P. and FHMLS XI, L.L.C. is the general partner of FHMLS XI, L.P. Patrick J. Heron, James N. Topper and Daniel Estes are the members of FHMLS XI, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences XI, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 FHMLS XI, L.L.C.

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 Delaware

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 3,000 shares (1)

 Sole Dispositive Power

 0

 Shared Dispositive Power

 3,000 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 3,000 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 0.0% (2)

 Type of Reporting Person (See Instructions)

 OO

Consists of 3,000 shares of Common Stock held directly by Frazier Life Sciences XI, L.P. FHMLS XI, L.P. is the general partner of by Frazier Life Sciences XI, L.P. and FHMLS XI, L.L.C. is the general partner of FHMLS XI, L.P. Patrick J. Heron, James N. Topper and Daniel Estes are the members of FHMLS XI, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences XI, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 James N. Topper

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 United States Citizen

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 5,985,347 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 5,985,347 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 5,985,347 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 18.8% (2)

 Type of Reporting Person (See Instructions)

 IN

Consists of (i) 1,103,920 shares of Common Stock held directly by Frazier Life Sciences Public Fund, L.P., (ii) 325,653 shares of Common Stock held directly by Frazier Life Sciences Public Overage Fund, L.P., (iii) 4,552,774 shares of Common Stock held directly by Frazier Life Sciences X, L.P. and (iv) 3,000 shares of Common Stock held directly by Frazier Life Sciences XI, L.P. FHMLSP, L.P. is the general partner of Frazier Life Sciences Public Fund, L.P. and FHMLSP, L.L.C. is the general partner of FHMLSP, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Fund, L.P. FHMLSP Overage, L.P. is the general partner of Frazier Life Sciences Public Overage Fund, L.P. and FHMLSP Overage, L.L.C. is the general partner of FHMLSP Overage, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP Overage, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Overage Fund, L.P. FHMLS X, L.P. is the general partner of Frazier Life Sciences X, L.P. and FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. Patrick J. Heron and James N. Topper are the members of FHMLS X, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences X, L.P. FHMLS XI, L.P. is the general partner of by Frazier Life Sciences XI, L.P. and FHMLS XI, L.L.C. is the general partner of FHMLS XI, L.P. Patrick J. Heron, James N. Topper and Daniel Estes are the members of FHMLS XI, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences XI, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 Patrick J. Heron

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 United States Citizen

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 5,985,347 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 5,985,347 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 5,985,347 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 18.8% (2)

 Type of Reporting Person (See Instructions)

 IN

Consists of (i) 1,103,920 shares of Common Stock held directly by Frazier Life Sciences Public Fund, L.P., (ii) 325,653 shares of Common Stock held directly by Frazier Life Sciences Public Overage Fund, L.P., (iii) 4,552,774 shares of Common Stock held directly by Frazier Life Sciences X, L.P. and (iv) 3,000 shares of Common Stock held directly by Frazier Life Sciences XI, L.P. FHMLSP, L.P. is the general partner of Frazier Life Sciences Public Fund, L.P. and FHMLSP, L.L.C. is the general partner of FHMLSP, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Fund, L.P. FHMLSP Overage, L.P. is the general partner of Frazier Life Sciences Public Overage Fund, L.P. and FHMLSP Overage, L.L.C. is the general partner of FHMLSP Overage, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP Overage, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Overage Fund, L.P. FHMLS X, L.P. is the general partner of Frazier Life Sciences X, L.P. and FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. Patrick J. Heron and James N. Topper are the members of FHMLS X, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences X, L.P. FHMLS XI, L.P. is the general partner of by Frazier Life Sciences XI, L.P. and FHMLS XI, L.L.C. is the general partner of FHMLS XI, L.P. Patrick J. Heron, James N. Topper and Daniel Estes are the members of FHMLS XI, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences XI, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 Albert Cha

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 United States Citizen

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 1,429,573 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 1,429,573 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 1,429,573 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 4.5% (2)

 Type of Reporting Person (See Instructions)

 IN

Consists of (i) 1,103,920 shares of Common Stock held directly by Frazier Life Sciences Public Fund, L.P., and (ii) 325,653 shares of Common Stock held directly by Frazier Life Sciences Public Overage Fund, L.P. FHMLSP, L.P. is the general partner of Frazier Life Sciences Public Fund, L.P. and FHMLSP, L.L.C. is the general partner of FHMLSP, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Fund, L.P. FHMLSP Overage, L.P. is the general partner of Frazier Life Sciences Public Overage Fund, L.P. and FHMLSP Overage, L.L.C. is the general partner of FHMLSP Overage, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP Overage, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Overage Fund, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 James Brush

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 United States Citizen

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 1,429,573 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 1,429,573 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 1,429,573 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 4.5% (2)

 Type of Reporting Person (See Instructions)

 IN

Consists of (i) 1,103,920 shares of Common Stock held directly by Frazier Life Sciences Public Fund, L.P., and (ii) 325,653 shares of Common Stock held directly by Frazier Life Sciences Public Overage Fund, L.P. FHMLSP, L.P. is the general partner of Frazier Life Sciences Public Fund, L.P. and FHMLSP, L.L.C. is the general partner of FHMLSP, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Fund, L.P. FHMLSP Overage, L.P. is the general partner of Frazier Life Sciences Public Overage Fund, L.P. and FHMLSP Overage, L.L.C. is the general partner of FHMLSP Overage, L.P. Patrick J. Heron, James N. Topper, Albert Cha and James Brush are the members of FHMLSP Overage, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences Public Overage Fund, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

 Name of Reporting Persons.

 Daniel Estes

 Check the Appropriate Box if a Member of a Group (See Instructions)

 (a) ☐  (b) ☒

 SEC USE ONLY

 Source of Funds (See Instructions)

 AF

 Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e)

 ☐

 Citizenship or Place of Organization

 United States Citizen

Number of

Shares

Beneficially 

Owned by

Each

Reporting

Person

With:

 Sole Voting Power

 0 shares

 Shared Voting Power

 3,000 shares (1)

 Sole Dispositive Power

 0 shares

 Shared Dispositive Power

 3,000 shares (1)

 Aggregate Amount Beneficially Owned by Each Reporting Person

 3,000 shares (1)

 Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See Instructions)

 ☐

 Percent of Class Represented by Amount in Row (11)

 0.0% (2)

 Type of Reporting Person (See Instructions)

 IN

Consists of 3,000 shares of Common Stock held directly by Frazier Life Sciences XI, L.P. FHMLS XI, L.P. is the general partner of by Frazier Life Sciences XI, L.P. and FHMLS XI, L.L.C. is the general partner of FHMLS XI, L.P. Patrick J. Heron, James N. Topper and Daniel Estes are the members of FHMLS XI, L.L.C. and therefore share voting and investment power over the shares held by Frazier Life Sciences XI, L.P.

Based on 31,853,698 shares of Common Stock that were anticipated to be outstanding following the Issuer’s initial public offering as set forth in the Issuer’s final prospectus filed with the SEC pursuant to Rule 424(b)(5) on September 13, 2024.

Security and Issuer.

Identity and Background

Name:

Residence or Business Address:

Present principal occupation or employment and the name, principal business and address of any corporation or other organization in which such employment is conducted:

Whether or not, during the last five years, such person has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) and, if so, give the dates, nature of conviction, name and location of court, and penalty imposed, or other disposition of the case:

Whether or not, during the last five years, such person was a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws; and, if so, identify and describe such proceedings and summarize the terms of such judgment, decree or final order:

Citizenship:

Source and Amount of Funds or Other Consideration

Purpose of Transaction

The acquisition by any person of additional securities of the Issuer, or the disposition of securities of the Issuer;

An extraordinary corporate transaction, such as a merger, reorganization or liquidation, involving the Issuer or any of its subsidiaries;

A sale or transfer of a material amount of assets of the Issuer or any of its subsidiaries;

Any change in the present board of directors or management of the Issuer, including any plans or proposals to change the number or term of directors or to fill any existing vacancies on the board;

Any material change in the present capitalization or dividend policy of the Issuer;

Any other material change in the Issuer’s business or corporate structure;

Changes in the Issuer’s charter, bylaws or instruments corresponding thereto or other actions which may impede the acquisition of control of the Issuer by any person;

Causing a class of securities of the Issuer to be delisted from a national securities exchange or to cease to be authorized to be quoted in an inter-dealer quotation system of a registered national securities association;

A class of equity securities of the Issuer becoming eligible for termination of registration pursuant to Section 12(g)(4) of the Securities Exchange Act of 1934, as amended; or

Any action similar to any of those enumerated above.

Interest in Securities of the Issuer

State the aggregate number and percentage of the class of securities identified pursuant to Item 1 (which may be based on the number of securities outstanding as contained in the most recently available filing with the Commission by the issuer unless the filing person has reason to believe such information is not current) beneficially owned (identifying those shares which there is a right to acquire) by each person named in Item 2. The information should also be furnished with respect to persons who, together with any of the persons named in Item 2, comprise a group within the meaning of Section 13(d)(3) of the Act:

For each person named in response to paragraph (a), indicate the number of shares as to which there is sole power to vote or to direct the vote, shared power to vote or to direct the vote, sole power to dispose or to direct the disposition, or shared power to dispose or to direct the disposition. Provide the applicable information required by Item 2 with respect to each person with whom the power to vote or to direct the vote or to dispose or direct the disposition is shared:

Sole power to vote or to direct the vote: See line 7 of cover sheets.

Shared power to vote or to direct the vote: See line 8 of cover sheets.

Sole power to dispose or to direct the disposition: See line 9 of cover sheets.

Shared power to dispose or to direct the disposition: See line 10 of cover sheets.

Describe any transactions in the class of securities reported on that were effected during the past sixty days or since the most recent filing of Schedule 13D (§240.13d-191), whichever is less, by the persons named in response to paragraph (a):

Date of

Transaction

These shares were purchased in a private transaction and later converted into 623,608 shares of the Issuer’s Common Stock upon closing of the IPO.

Date of

Transaction

Date of

Transaction

Date of

Transaction

These shares were purchased in a private transaction and later converted into 183,965 shares of the Issuer’s Common Stock upon closing of the IPO.

Date of

Transaction

Date of

Transaction

Date of

Transaction

Date of

Transaction

Date of

Transaction

Date of

Transaction

Date of

Transaction

Date of

Transaction

Date of

Transaction

Date of

Transaction

Date of

Transaction

Date of

Transaction

Date of

Transaction

If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than five percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of an employee benefit plan, pension fund or endowment fund is not required:

If applicable, state the date on which the reporting person ceased to be the beneficial owner of more than five percent of the class of securities:

Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer

Material to Be Filed as Exhibits

Agreement regarding filing of joint Schedule 13D.

Form of Lock-up Agreement (incorporated by reference to Exhibit D to that certain Underwriting Agreement between the Issuer and the Underwriters (as defined therein) filed as Exhibit 1.1 to the Issuer’s Registration Statement on Form S-1/A filed with the Commission on September 9, 2024).

Second Amended and Restated Investors’ Rights Agreement (incorporated by reference to Exhibit 4.1 to the Issuer’s Registration Statement on Form S-1 filed with the Commission on August 23, 2024).

/s/ Steve R. Bailey

/s/ Steve R. Bailey

/s/ Steve R. Bailey

/s/ Steve R. Bailey

/s/ Steve R. Bailey

/s/ Steve R. Bailey

/s/ Steve R. Bailey

/s/ Steve R. Bailey

/s/ Steve R. Bailey

/s/ Steve R. Bailey

/s/ Steve R. Bailey

/s/ Steve R. Bailey

*

*

**

**

***

/s/ Steve R. Bailey

This Schedule 13D was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on July 31, 2017.

This Schedule 13D was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on August 16, 2021.

This Schedule 13D was executed by Steve R. Bailey on behalf of the individual listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on April 18, 2022.

FHMLSP OVERAGE, L.P.

This Agreement was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on July 31, 2017.

This Agreement was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on August 16, 2021.

This Agreement was executed by Steve R. Bailey on behalf of the individual listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on April 18, 2022.