Immunotherapy has been a breakthrough approach for metastatic melanoma, such as anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and anti-programmed cell death protein 1 (PD-1) antibodies, which are based on the activation of the anticancer immune system (Marzagalli et al., 2019). The gene discussed is PDCD1; the disease is metastatic melanoma.