Arcus Biosciences to Present First Combination Data for HIF-2a Inhibitor Casdatifan Plus Cabozantinib in an Oral Presentation at the 2025 ASCO Annual Meeting

• New data from the Phase 1/1b ARC-20 cohort evaluating HIF-2a inhibitor casdatifan in combination with cabozantinib in clear cell renal cell carcinoma (ccRCC) will be presented in an oral session by Dr. Toni Choueiri, Dana-Farber Cancer Institute

• The ASCO presentation will include a more mature data cut than that described in the abstract and will include safety and initial efficacy data for the 100mg casdatifan once-daily (QD) plus 60mg cabozantinib QD cohort

• Arcus will host a conference call to discuss the ARC-20 data at 5:00 AM PT / 7:00 AM CT on Monday, June 2, 2025

Arcus Biosciences, Inc. (NYSE:RCUS), a clinical-stage, global biopharmaceutical company focused on developing differentiated molecules and combination therapies for people with cancer, today announced that data from the ARC-20 study will be presented in an oral session at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting taking place May 30 – June 3, 2025.

The oral presentation will highlight the first safety and efficacy data for the ARC-20 expansion cohort evaluating the HIF-2a inhibitor casdatifan plus cabozantinib, an anti-vascular endothelial growth factor receptor 2 tyrosine kinase inhibitor (VEGFR2-TKI), in patients with ccRCC that had previously been treated with immunotherapy alone or in combination with anti-VEGFR2-TKI therapies.

"We are thrilled to be presenting the first combination data evaluating our HIF-2a inhibitor, casdatifan, in combination with cabozantinib in an oral presentation at ASCO," said Terry Rosen, Ph.D., chief executive officer of Arcus. "The data being presented support our rapidly advancing and differentiated development program for casdatifan, which includes the initiation of our Phase 3 trial, PEAK-1, that will evaluate the same combination as this cohort. The development plan also includes our clinical collaboration to evaluate casdatifan in combination with AstraZeneca's PD-1/CTLA-4 bispecific antibody, volrustomig, in immuno-oncology-naive ccRCC patients. We look forward to presenting additional data from the ARC-20 study throughout the year."

Investors may dial in to the conference call at +1 404 975 4839 (local) or +1 833 470 1428 (toll-free) using Conference ID: 446724 on Monday, June 2, 2025, at 5:00 AM PT / 7:00 AM CT. Participants may also register for the call online using the following link: https://events.q4inc.com/attendee/154065244. To access the live webcast and accompanying slide presentation, please visit the "Investors & Media" section of the Arcus Biosciences website at www.arcusbio.com. A replay will be available following the live event.

About RCC

According to the American Cancer Society, kidney cancer is among the top 10 most commonly diagnosed forms of cancer among both men and women in the U.S., and an estimated 80,980 Americans will be diagnosed with kidney cancer in 2025. Clear cell RCC is the most common type of kidney cancer in adults. If detected in its early stages, the five-year survival rate for RCC is high; for patients with advanced or late-stage metastatic RCC, however, the five-year survival rate is only 18%. In 2022, approximately 32,200 patients with advanced kidney cancer required systemic therapy in the U.S., with over 20,000 patients receiving first-line treatment.

About Casdatifan (AB521)

Casdatifan is a small-molecule inhibitor of HIF-2a, a transcription factor responsible for activating multiple tumor growth pathways in hypoxic and pseudo-hypoxic tumor environments. By selectively binding HIF-2⍺, casdatifan is designed to shut down hypoxic oncogenesis, which blocks tumor growth and key oncogenic pathways, leading to cancer cell death. Clear cell RCC (ccRCC) is almost universally associated with HIF-2a dysregulation. Casdatifan is currently being evaluated in ARC-20, a Phase 1/1b study in renal cell carcinoma and other cancers.

Casdatifan is an investigational molecule. Approval from any regulatory authority for its use has not been received, and its safety and efficacy have not been established.

About Arcus Biosciences

Arcus Biosciences is a clinical-stage, global biopharmaceutical company developing differentiated molecules and combination therapies for people with cancer. In partnership with industry collaborators, patients and physicians around the world, Arcus is expediting the development of first- or best-in-class medicines against well-characterized biological targets and pathways and studying novel, biology-driven combinations that have the potential to help people with cancer live longer. Founded in 2015, the company has expedited the development of multiple investigational medicines into clinical studies, including new combination approaches that target TIGIT, PD-1, HIF-2a, CD73, A2a/A2b receptors, CD39, and AXL. For more information about Arcus Biosciences' clinical and preclinical programs, please visit www.arcusbio.com.

Forward-Looking Statements

This press release contains forward-looking statements. All statements regarding events or results to occur in the future contained herein are forward-looking statements reflecting the current beliefs and expectations of management made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, including, but not limited to, the statements in Dr. Rosen's quote and statements regarding how data from ARC-20 will support or advance Arcus's development program for casdatifan, including plans for future development. All forward-looking statements involve known and unknown risks and uncertainties and other important factors that may cause Arcus's actual results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to: risks associated with preliminary and interim data not being guarantees that future data will be similar; the unexpected emergence of adverse events or other undesirable side effects in Arcus's investigational products; difficulties or delays in initiating or conducting clinical trials due to difficulties or delays in the regulatory process, enrolling subjects or manufacturing or supplying product for such clinical trials; unfavorable global economic, political and trade conditions; Arcus's dependence on the collaboration with third parties such as Gilead and Taiho for the successful development and commercialization of its optioned molecules; difficulties associated with the management of the collaboration activities or expanded clinical programs; changes in the competitive landscape for Arcus's programs; and the inherent uncertainty associated with pharmaceutical product development and clinical trials. Risks and uncertainties facing Arcus are described more fully in the "Risk Factors" section of Arcus's most recent periodic report filed with the U.S. Securities and Exchange Commission. You are cautioned not to place undue reliance on the forward-looking statements, which speak only as of the date of this press release. Arcus disclaims any obligation or undertaking to update, supplement or revise any forward-looking statements contained in this press release except to the extent required by law.

The Arcus name and logo are trademarks of Arcus Biosciences, Inc. All other trademarks belong to their respective owners.

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