There are several factors associated with ICI resistance: loss of expression of PD-1/PD-L1 in tumor and antigen-presenting cells [23,41]; low mutation burden limiting tumor associated antigen expression; canonical Wnt/β-catenin pathway activation affecting immune-mediated cell infiltration [42,43,44]; β−2 microglobulin mutations impairing antigen presentation [35,45,46]; and alterations in the janus kinase-signal transducers and activators of transcription pathway affecting interferon-γ signaling [36]. This evidence concerns the gene PDCD1 and neoplasm.