PDCD1 and melanoma: Multiple solid tumors, including non-small cell lung cancer (NSCLC) [5], melanoma [6], triple negative breast cancer (TNBC] [7], liver cancer [8], and cervical cancer [9], as well as blood cancers like Hodgkin’s lymphoma (HL) [10] and NK/T-cell lymphoma, have been treated with PD-1/PD-L1 inhibitory drugs.