Arcus Biosciences to Present First Clinical Data from ARC-20 Study at the 2024 EORTC-NCI-AACR Symposium

• Data from the 100mg expansion cohort of ARC-20, a Phase 1/1b study of casdatifan in clear cell renal cell carcinoma (ccRCC), will be presented in an oral plenary session by Dr. Toni Choueiri, Dana-Farber Cancer Institute.

• Two posters will be presented on the preclinical evaluation and human pharmacokinetics/ pharmacodynamics of casdatifan, respectively, and a third poster will be presented on AB801, Arcus's AXL inhibitor.

• Arcus will also host a conference call to discuss the ARC-20 results at 5:00 AM PT / 8:00 AM ET on Thursday, October 24, 2024.

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 four accepted abstracts at the 2024 EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapeutics being held October 23-25, 2024, in Barcelona, Spain. The data being presented include a growing body of evidence supporting the potential of casdatifan as a best-in-class HIF-2a inhibitor for the treatment of ccRCC.

The oral presentation will highlight data from the approximately 30 patients in the 100mg daily monotherapy expansion cohort of ARC-20, a Phase 1/1b study evaluating casdatifan in late-line ccRCC. It will include data on safety and efficacy, including objective response rate and rate of primary progression, as well as other data to assess the depth and duration of responses. The presentation will also highlight data from the 50mg monotherapy expansion cohort of approximately 30 patients in the same setting.

"We are thrilled to be presenting the first clinical efficacy data from the ARC-20 study for our HIF-2a inhibitor, casdatifan, in an oral plenary session, as well as two additional posters that further highlight the differentiation of casdatifan in ccRCC and the therapeutic opportunities in other tumor types," said Terry Rosen, Ph.D., chief executive officer of Arcus. "These data support a potential best-in-class profile, and we are rapidly advancing a differentiated development program for casdatifan, including the planned initiation of our first Phase 3 study in the first half of 2025."

Arcus is pursuing a broad development program in both the first-line and post-anti-PD-1 settings with differentiated combinations to maximize the opportunity for casdatifan in ccRCC. In addition to the monotherapy cohorts of ARC-20, the study is also enrolling a cohort to evaluate casdatifan in combination with cabozantinib, a VEGFR tyrosine kinase inhibitor, which is intended to support the initiation of Arcus's first Phase 3 study, PEAK-1, evaluating casdatifan in combination with cabozantinib versus cabozantinib monotherapy in patients with metastatic ccRCC who have previously received anti-PD-1 therapy. The primary endpoint will be progression-free survival with a key secondary endpoint of overall survival. Arcus also recently announced a clinical collaboration as part of its first-line strategy in advanced first-line ccRCC to evaluate casdatifan in combination with volrustomig, an investigational PD-1/CTLA-4 bispecific antibody.

Investors may dial in to the conference call at +1 (404) 975-4839 (local) or +1 (833) 470-1428 (toll-free), using Conference ID: 595409 on Thursday, October 24, 2024, at 5:00 AM PT / 8:00 AM ET. 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.

Four Accepted Abstracts Will Be Presented

About Arcus Biosciences

Arcus Biosciences is a clinical-stage, global biopharmaceutical company developing differentiated molecules and combination medicines 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, dual A2a/A2b receptor, CD39, and AXL. For more information about Arcus Biosciences' clinical and preclinical programs, please visit www.arcusbio.com.

Casdatifan and AB801 are investigational molecules, and Arcus has not received approval from any regulatory authority for any commercial use globally, and their safety and efficacy have not been established.

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: the potency, efficacy or safety of casdatifan, including its potential for a best-in-class profile; how data from ARC-20 will support or advance Arcus's development program for casdatifan, including plans for future development; plans to initiate a new Phase 3 study with casdatifan; and combinations that Arcus plans to explore in future studies. 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: interim data not being replicated in future studies evaluating the same investigational molecules or regimen; the unexpected emergence of adverse events or other undesirable side effects in Arcus's investigational products, including domvanalimab and zimberelimab; risks associated with the manufacturing or supplying product for such clinical trials; uncertainties in timelines associated with the conduct of clinical studies and with respect to the regulatory application process; Arcus's dependence on the collaboration with Gilead for the successful development and commercialization of its optioned molecules; difficulties associated with the management of the collaboration activities with our strategic partners 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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