In view of their encouraging results in anti-tumor function, ICIs involved with CTLA-4 inhibitors (ipilimumab), PD-1 inhibitors (nivolumab, pembrolizumab, and cemiplimab), and PD-L1 inhibitors (atezolizumab, avelumab, and durvalumab) have been approved by the FDA to treat numerous types of solid tumors: Hodgkin and non-Hodgkin lymphomas, melanoma, Merkel cell carcinoma, and liver, kidney, cervical, head and neck, lung, gastric, colorectal, and bladder cancers, and cutaneous squamous cell carcinoma (100). Here, PDCD1 is linked to melanoma.