Immune checkpoint blockade (ICB) therapies, such as programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) inhibitors and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors, have exhibited promising therapeutic effects in the treatment of various malignancies, such as non-small cell lung cancer (NSCLC) and melanoma. Here, PDCD1 is linked to melanoma.