There are three classes of ICIs in widespread use, each of which augments the anti-tumor response by blocking either the receptor or the ligand in one of the aforementioned pathways: anti-CTLA-4 ICIs, such as ipilimumab and tremelimumab; anti-PD-1 ICIs, such as nivolumab, pembrolizumab, and cemiplimab; and anti-PD-L1 ICIs, such as atezolizumab, avelumab, and durvalumab (Figure 2) [2,3,4,5,6,7,8,9]. This evidence concerns the gene PDCD1 and neoplasm.