How to better select patients with advanced gastric cancer for immunotherapy

Concomitantly to the development of biological agents in the treatment of gastric cancer, immunotherapy has revolutionized the oncology landscape by targeting the host immune system. The efficacy of immunotherapy seems to be related to the immune microenvironment of the tumor and its immunogenicity. Blocking immune checkpoint has already proven efficacy in several solid cancers (1). Based on phase II trials, the FDA has already approved the pembrolizumab (anti-PD-1 monoclonal antibody) for the treatment of patients with refractory advanced gastric cancer expressing PD-L1 [combined positive score (CPS) ≥1%] (2) or for the treatment of patients with refractory advanced solid tumors with dMMR/MSI (deficient mismatch repair/microsatellite instability) phenotype (3). However, different studies with immunotherapy have showed a rather wide range of tumor response rate in gastric cancer, highlighting the need to identify biomarkers to better select patients who might benefit most from immune checkpoint inhibitors.