The company reported strong survival data from its mid-stage trial combining domvanalimab and zimberelimab with chemotherapy in advanced stomach and esophageal cancer.
Retail chatter around Arcus Biosciences picked up late Sunday after the company reported that its experimental cancer drug combination — domvanalimab and zimberelimab, given with chemotherapy — helped patients with advanced stomach and esophageal cancer live a median of 26.7 months in a mid-stage (Phase 2) study.
The first overall survival results from Arm A1 of the trial will be presented on Oct. 18 at the European Society for Medical Oncology 2025 Congress, with data supporting ongoing development of the regimen in the Phase 3 STAR-221 study.
According to the company’s statement, half of the patients enrolled in Arm A1 lived more than two years following treatment with domvanalimab plus zimberelimab and chemotherapy. Median progression-free survival reached 12.9 months, while confirmed objective response rate stood at 59% across all PD-L1 subgroups.
Sun Young Rha, professor of Medical Oncology in the Department of Internal Medicine at Yonsei University College of Medicine, said the 26.7-month survival “is well beyond what would be required to demonstrate clinically meaningful benefit over standard of care.”
As of March 3, the treatment demonstrated benefits across various patient groups based on PD-L1, a protein that enables tumors to evade the immune system, with approximately half of the patients still alive two years after initiating therapy. No new safety concerns were seen, and side effects were similar to what’s usually expected with immune therapy and chemotherapy.
Arcus, working together with Gilead Sciences, is studying how combinations of anti-TIGIT and anti-PD-1 therapies might help people with advanced stomach and esophageal cancers.
The ongoing Phase 3 STAR-221 trial has already enrolled over 1,000 patients around the world to see whether the domvanalimab and zimberelimab combo can perform better than current treatments using nivolumab. Both drugs are still experimental and have not yet been approved by regulators.
One user said that the results showed more than a year of added survival compared with current treatments, calling it an “unprecedented” outcome for such a hard-to-treat cancer.
Another user praised the 26-month figure as a standout result, saying it easily surpassed data from the CheckMate-649 study.
Arcus Biosciences’ stock has declined 2% so far in 2025.
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