PDCD1 and neoplasm: Evaluation of the radiopharmaceutical in numerous immunogenically “cold” and “hot” syngeneic tumor models treated with Sym021, an anti-PD-1 antibody, found that maximum tumor-to-heart values at the start of treatment were significantly able to predict response to therapy with immunologically cold tumors, with those that were poorly immune infiltrated being non-responders and those that were immunology hot, or highly tumor infiltrated, being responders to immunotherapy (60).