Based on this evidence, the Food and Drug Administration (FDA) approved programmed cell death protein-1 (PD-1) inhibitors monotherapy (and cytotoxic T lymphocyte-associated antigen 4 inhibitors) for patients with MSI-H/dMMR colorectal cancer and multiple other cancers, regardless of the location [3, 8–11]. The gene discussed is PDCD1; the disease is colorectal cancer.