Predictive biomarkers and new developments of immunotherapy in gastric cancer: a 2023 update

Gastric cancer is an extremely common digestive tract tumor. The promotion and application of standardized therapy, treatment scheme optimization, and development of new targeted drugs and immunotherapies have improved gastric cancer survival somewhat. However, gastric cancer prognosis generally remains non-optimistic. Immune checkpoint inhibitors (ICI) have gradually become a new choice for gastric cancer treatment and can prolong the survival of some patients. Among them, high-microsatellite instability, Epstein-Barr virus-positive status, or high-tumor mutational burden patients with gastric cancer may be the potential population to benefit from immunotherapy. Nevertheless, there remains a lack of unified and effective predictive markers. Accordingly, this review mainly focused on the possible predictive biomarkers of anti-PD-1/PD-L1 in gastric cancer treatment. Furthermore, the application of anti-PD-1/PD-L1 therapy-related clinical trials on gastric cancer is discussed. The current findings suggest that immunotherapy is a promising application in gastric cancer treatment. Therefore, combining immunotherapy and other therapies may be the trend in the future. Nevertheless, exploring biomarkers to predict ICI response remains a major challenge.