PDCD1 and melanoma: Since 2012, numerous clinical reports (11–19) have shown the unprecedented efficacy of anti-PD antibodies for the treatment of metastatic bladder cancer, renal-cell cancer, colorectal cancer (CRC), non–small-cell lung cancer (NCSLC), and melanoma, etc. Frustratingly, durable responses to PD-1/PD-L1 antibodies are only achieved in about 10-40% of patients, with the majority not benefiting (20).