In fact, immune checkpoint blockade (ICB) with anti-programmed cell death 1 (anti-PD-1), anti-programmed cell death ligand 1 (anti-PD-L1), and anti-CTLA-4 antibodies have demonstrated their clinical efficacy in treating previously untreatable advanced-stage cancer patients since 2011 [1,2]. Here, PDCD1 is linked to cancer.