PDCD1 and cancer: To date, numerous immune checkpoint blockade (ICB) therapies have received FDA approval for use in cancer treatment, including two CTLA-4 inhibitors (ipilimumab and tremelimumab), eight PD-1 inhibitors (nivolumab, pembrolizumab, cemiplimab, dostarlimab, retifanlimab, toripalimab, tislelizumab, and penpulimab), four PD-L1 inhibitors (atezolizumab, durvalumab, avelumab, and cosibelimab), and one LAG-3 inhibitor (relatlimab) [9].