CD274 and neoplasm: Prior studies also identified multiple additional mechanisms of intrinsic or acquired resistance, including decreased expression of programmed death ligand 1 (PD-L1), increased upregulation of other immune checkpoints, alternative defects in antigen presentation or T cell activation, and reduced T cell trafficking and tumor infiltration or other alterations in the tumor microenvironment.3,6–9 Thus, antigen presentation and innate immune pathways play important roles in both intrinsic and acquired resistance to ICIs.