Open-label, non-randomized, Phase 1b/2 trial investigating the safety, tolerability, and antitumor activity of S095029 (anti-NKG2A antibody) as a part of combination therapy in participants with locally advanced and unresectable or metastatic MSI-H/dMMR gastroesophageal junction/gastric cancer

A new drug combination is being tested in people with advanced stomach cancer that has spread to other parts of the body. This matters because gastric and gastroesophageal junction cancers that are mismatch repair deficient (MSI-H/dMMR) often do not respond well to standard treatments, and new options are urgently needed. The study combines S095029, an experimental antibody that blocks a natural brake on immune cells called NKG2A, with pembrolizumab, an existing immunotherapy that releases a different immune checkpoint. The idea is that blocking two separate immune-suppressing pathways at once might shrink tumours that resist single-agent immunotherapy. If the combination proves safe and active, it could offer a new treatment pathway for patients with this specific genetic subtype of stomach cancer, who currently have limited choices. The research is a clinical trial, not fundamental science—it directly tests a potential therapy in people. Success would mean a new drug regimen entering later-stage trials, potentially changing clinical practice for a hard-to-treat cancer population.