Specifically, anti-programmed cell death protein 1 (PD-1) antibodies have shown more durable anticancer immunity and longer survival in untreated metastatic GC patients with highly unstable microsatellites (microsatellite instability-high (MSI-H)/deficient mismatch repair (dMMR)) (Chao et al. 2021). The gene discussed is PDCD1; the disease is gastric cancer.