RXDX Prometheus Biosciences Inc

Prometheus Biosciences, Inc. (Nasdaq: RXDX), a clinical-stage biotechnology company pioneering a precision medicine approach for the discovery, development, and commercialization of novel therapeutics for the treatment of immune-mediated diseases, today announced two oral presentations on PRA023 at the 18th Congress of European Crohn’s and Colitis Organisation (ECCO), taking place in Copenhagen, Denmark, March 1- 4, 2023.

The presentations will review the positive Phase 2 data on PRA023 from both UC and CD studies reported in December 2022. All primary and secondary endpoint data from Cohort 1 of the ARTEMIS-UC study will be presented as well as additional subgroup analyses including prior exposure to advanced therapies. The company also plans to present primary and key secondary endpoint data for the APOLLO-CD Study along with disease surrogate biomarker levels and subgroup analyses including prior exposure to biologics.

Oral Presentation Details:

Title: “The Anti-TL1A Antibody PRA023 Demonstrated Proof-of-Concept in Crohn’s Disease: Phase 2a APOLLO-CD Study Results” Session title/type: DOP Session 10: Therapy: Biologics, Digital oral presentation  Presenter: Brian G. Feagan, MD, FRCPC, Professor of Medicine, Epidemiology and Biostatistics, Western UniversitySession Date/Time: Friday, March 3, 2023, 17:55 - 18:01Session hall: Room C-M4-5

Title: “PRA023 Demonstrated Efficacy and Favorable Safety as Induction Therapy for Moderately to Severely Active UC: Phase 2 ARTEMIS-UC Study Results” Session title/type: Sequencing in IBD - Scientific Session 11: Fibrosis in IBD, Scientific Programme, Oral presentation  Presenter: Bruce E. Sands, MD, MS, Professor of Medicine, Gastroenterology, Icahn School of Medicine, Mount SinaiSession Date/Time: Saturday, March 4, 2023, 11:50-12:00Session hall: Plenary Hall

About Prometheus Biosciences

Prometheus Biosciences, Inc. is a clinical-stage biotechnology company pioneering a precision medicine approach for the discovery, development, and commercialization of novel therapeutics for the treatment of immune-mediated diseases. The Company’s target discovery engine, Prometheus360TM, combines proprietary machine learning-based analytical approaches with one of the world’s largest gastrointestinal bioinformatics databases to identify novel therapeutic targets and develop therapeutic candidates to engage those targets.

The Company’s lead candidate, PRA023, is a humanized IgG1 monoclonal antibody (mAb) that has been shown to block the tumor necrosis factor (TNF)-like ligand 1A (TL1A), a target associated with both intestinal inflammation and fibrosis. Prometheus is developing PRA023 for the treatment of immune-mediated diseases including ulcerative colitis (UC), Crohn’s Disease (CD), and systemic sclerosis-associated interstitial lung disease (SSc-ILD).   The Company plans to advance PRA023 into Phase 3 trials in UC and CD later this year.

Forward Looking Statements

Prometheus cautions readers that statements contained in this press release regarding matters that are not historical facts are forward-looking statements. These statements are based on the company’s current beliefs and expectations. Such forward-looking statements include, but are not limited to statements regarding: the potential of PRA023 to improve IBD treatment and to be both a first-in-class and best-in-class anti-TL1A mAb; the potential of PRA052 to be a first-in-class mAb blocking CD30L; the timing of results from Cohort 2 of the ARTEMIS-UC trial, topline results from the ATHENA-SSc-ILD trial, and results from the Phase 1 NHV study of PRA052; plans to advance PRA023 into Phase 3 trials in UC and CD, including the timing thereof; plans to submit an IND for PR1100, including the timing thereof; plans to develop diagnostic candidates; and the potential of Prometheus’ diagnostic candidates to identify potential responders. The inclusion of forward-looking statements should not be regarded as a representation by Prometheus that any of its plans will be achieved. Actual results may differ from those set forth in this press release due to the risks and uncertainties inherent in our business, including, without limitation: topline results Prometheus reports are based on preliminary analysis of key efficacy and safety data, and such data may change following a more comprehensive review of the data related to the clinical trial and such topline data may not accurately reflect the complete results of a clinical trial; Prometheus’ approach to the discovery and development of precision medicines based on Prometheus360TM is unproven; interim results of a clinical trial do not predict final results and the clinical outcomes may materially change following more comprehensive reviews of the data, as follow-up on the outcome of any particular patient continues and as more patient data become available, including from Cohort 2 of the ARTEMIS-UC trial; potential delays in the commencement, enrollment and completion of clinical trials and preclinical studies; the results of clinical trials are not necessarily predictive of future results; Prometheus’ dependence on third parties in connection with product manufacturing, research and preclinical and clinical testing; Prometheus’ ability to develop companion diagnostics for its therapeutic product candidates; unexpected adverse side effects or inadequate efficacy of its product candidates that may limit their development, regulatory approval and/or commercialization, or may result in recalls or product liability claims; planned future trials of PRA023 may not support regulatory registration; regulatory developments in the United States and foreign countries; Prometheus’ ability to maintain undisrupted business operations due to the COVID-19 pandemic, including delaying or otherwise disrupting its preclinical studies, clinical trials, manufacturing and supply chain; and other risks described in the company’s prior press releases and filings with the Securities and Exchange Commission (SEC), including under the heading “Risk Factors” in Prometheus’ most recent annual report on Form 10-K and any subsequent filings with the SEC. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and Prometheus undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement, which is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

Contacts:

Noel KurdiVP Investor Relations and Communications(646) 241-4400nkurdi@prometheusbiosciences.com

Media contact:

Juniper PointAmy Conrad(858) 914-1962media@prometheusbiosciences.com