Tumor intrinsic factors, such as extensive heterogeneity in protein expression and mutational status, competition for limited nutrients, infiltration of CD8-supressing immune populations, such as Tregs and tumor-associated macrophages and secretion of immunosuppressive factors, can limit efficacy of endogenous T cells following immunotherapy as well as that of adoptively transferred CAR-T cells. Here, CD8A is linked to neoplasm.