Gilead and Arcus Report Over 1-Year Median PFS for Domvanalimab, Zimberelimab, and Chemo in First-Line Upper GI Cancer Treatment

Gilead Sciences, Inc. and Arcus Biosciences, Inc. have unveiled longer-term efficacy and safety data from Arm A1 of their Phase 2 EDGE-Gastric study. The study focuses on the combination of domvanalimab (an anti-TIGIT antibody), zimberelimab (an anti-PD-1 monoclonal antibody), and chemotherapy in treating patients with advanced, unresectable, or metastatic upper gastrointestinal (GI) cancers, including gastric, gastroesophageal junction, and esophageal adenocarcinomas. This data was presented at the American Society of Clinical Oncology (ASCO) Plenary Series: Rapid Abstract Updates session by Dr. Yelena Y. Janjigian, Chief of Gastrointestinal Oncology at Memorial Sloan Kettering Cancer Center and principal investigator for the EDGE-Gastric study.

Key efficacy results from the study include an objective response rate (ORR) and progression-free survival (PFS) metrics. Among the treated patients, a median PFS extending beyond one year was noted, surpassing historical benchmarks for anti-PD-1 therapies combined with chemotherapy alone. Almost 60% of the patients achieved PFS at the 12-month mark. The detailed breakdown of the efficacy outcomes indicated a median PFS of 12.9 months overall, 13.8 months for patients with high PD-L1 expression, and 11.3 months for those with low PD-L1 expression. The 12-month PFS rate stood at 57.6% overall, with specific rates of 68.8% for high PD-L1 patients and 46.8% for low PD-L1 patients.

Additional efficacy data showed an overall ORR of 58.5%, including a 68.8% ORR for patients with high PD-L1 expression and 50.0% for those with low PD-L1 expression. The study also recorded a complete response in 7.3% of patients and a partial response in 51.2%, with stable disease observed in 34.1% of participants.

No unforeseen safety issues were reported, indicating that the treatment regimen is generally well tolerated, with most adverse reactions being infusion-related and tied to chemotherapy. At the data cutoff on March 12, 2024, the median treatment duration was 49.4 weeks. The ongoing Phase 3 STAR-221 study aims to validate these findings further and is expected to finish enrolling participants by mid-2024. If successful, this regimen could become the first anti-TIGIT combination therapy available for these cancers.

Domvanalimab and zimberelimab are still investigational and have not received regulatory approval for any indication. Domvanalimab is designed to block the T-cell immunoreceptor with Ig and ITIM domains (TIGIT) without depleting peripheral regulatory T cells. Zimberelimab aims to restore T-cell antitumor activity by binding to the programmed cell death protein-1 (PD-1). Both drugs are being evaluated in various combinations across multiple tumor types in ongoing clinical trials.

Gilead Sciences is a biopharmaceutical company dedicated to developing innovative medicines to treat life-threatening diseases such as HIV, viral hepatitis, COVID-19, and cancer. Arcus Biosciences is a clinical-stage biopharmaceutical company focusing on developing novel cancer treatments through strategic industry collaborations and rigorous scientific research. Together, they aim to bring groundbreaking therapies to patients in need.