On June 10, 2024 Arcus Biosciences, Inc. (NYSE:RCUS), a clinical-stage, global biopharmaceutical company focused on developing differentiated molecules and combination therapies for people with cancer, reported the completion of patient enrollment for STAR-221, a Phase 3 study in collaboration with Gilead Sciences, evaluating the combination of the Fc-silent anti-TIGIT antibody domvanalimab plus the anti-PD-1 monoclonal antibody zimberelimab and chemotherapy in patients with locally advanced unresectable or metastatic gastric, gastroesophageal junction or esophageal adenocarcinoma (Press release, Arcus Biosciences, JUN 10, 2024, View Source [SID1234644237]).

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"STAR-221 completed enrollment well ahead of schedule, driven by significant interest from the global medical community in the potential for an anti-TIGIT-based regimen to address the high unmet need in this setting," said Dimitry S.A. Nuyten, M.D., Ph.D., chief medical officer of Arcus Biosciences. "Domvanalimab is the first and only anti-TIGIT antibody to be studied in a Phase 3 trial in upper gastrointestinal adenocarcinoma. We are now preparing for the readout and look forward to the potential opportunity to make a meaningful difference for patients with this disease."

Earlier this month at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting, Arcus and Gilead presented results from Arm A1 of the Phase 2 EDGE-Gastric study evaluating the same regimen in the same setting as the STAR-221 Phase 3 study. Data from this arm of EDGE-Gastric showed that patients treated with domvanalimab plus zimberelimab and chemotherapy had a median progression-free survival (PFS) of 12.9 months, which exceeds the historical benchmarks for anti-PD-1 plus chemotherapy alone. Notably, nearly 60% of patients in the EDGE-Gastric study achieved PFS at 12 months, and the domvanalimab plus zimberelimab and chemotherapy regimen demonstrated sustained improvement across efficacy measures, including in those patients who have low PD-L1 expression. No unexpected safety signals were observed at the time of data cutoff, March 12, 2024. The domvanalimab plus zimberelimab and chemotherapy regimen was generally well tolerated and showed an overall safety profile consistent with the known safety profiles of each individual molecule to date.

Domvanalimab and zimberelimab are investigational molecules. Neither Gilead nor Arcus has received approval from any regulatory authority for any use of these molecules, and their safety and efficacy for the treatment of gastrointestinal cancers have not been established.

About the STAR-221 Study

The ongoing, global STAR-221 trial (NCT05568095) enrolled approximately 1,050 participants with locally advanced unresectable or metastatic gastric, gastroesophageal junction, or esophageal adenocarcinoma. The primary endpoints of the study are overall survival in PD-L1-high tumors and in the intent-to-treat population (all PD-L1 levels); secondary endpoints include progression-free survival, objective response rate and duration of response. Participants were randomized 1:1 between two arms:

1600 mg of domvanalimab intravenously (IV) every four weeks plus 480 mg of zimberelimab IV every four weeks plus FOLFOX (oxaliplatin, leucovorin, fluorouracil) every two weeks or 1200 mg of domvanalimab plus 360 mg of zimberelimab every three weeks plus CAPOX (capecitabine and oxaliplatin) every three weeks
240 mg of nivolumab IV every two weeks plus FOLFOX every two weeks or 360 mg of nivolumab plus CAPOX every three weeks
About Domvanalimab

Domvanalimab is the first and most clinically advanced Fc-silent investigational monoclonal antibody that is specifically designed with Fc-silent properties to block and bind to the T-cell immunoreceptor with Ig and ITIM domains (TIGIT), a checkpoint receptor on immune cells that acts as a brake on the anticancer immune response. By binding to TIGIT with Fc-silent properties, domvanalimab is believed to work by freeing up immune-activating pathways and activate immune cells to attack and kill cancer cells without depleting the peripheral regulatory T cells important in avoiding immune-related toxicity.

Combined inhibition of both TIGIT and programmed cell death protein-1 (PD-1) is believed to significantly enhance immune cell activation, as these checkpoint receptors play distinct, complementary roles in anti-tumor activity. Domvanalimab is being evaluated in combination with anti-PD-1 monoclonal antibodies, including zimberelimab, as well as other investigational cancer immunotherapies and A2a/A2b adenosine receptor antagonist etrumadenant, in multiple ongoing and planned early and late-stage clinical studies in various tumor types.

About Zimberelimab

Zimberelimab is an anti-programmed cell death protein-1 (PD-1) monoclonal antibody that binds PD-1, with the goal of restoring the antitumor activity of T cells. Zimberelimab has demonstrated high affinity, selectivity and potency in various tumor types.

Zimberelimab is being evaluated in the U.S. and globally as a foundational anti-PD-1 treatment option in multiple ongoing and planned early and late-stage clinical studies in combination with other immunotherapies, including investigational Fc-silent anti-TIGIT monoclonal antibody domvanalimab and A2a/A2b adenosine receptor antagonist etrumadenant.

Guangzhou Gloria Biosciences Co. Ltd., which holds commercialization rights for zimberelimab in greater China, has obtained approval for zimberelimab for the treatment of recurrent or metastatic cervical cancer and for relapsed or refractory classical Hodgkin’s lymphoma. Zimberelimab is not approved for any use in the U.S. or other regions outside of China. Gloria conducts its development and commercialization activities independent of Arcus and Gilead.