ICIs, such as monoclonal antibodies targeting PD-1 (pembrolizumab, nivolumab), PD-L1 (atezolizumab, durvalumab, avelumab), and CTLA-4 (ipilimumab), have resulted in long-term responses in numerous tumor types (Table 1) [37,38,39]. Here, PDCD1 is linked to neoplasm.