IL21 and neoplasm: Finally, taking advantage of the host’s response to personalized neoantigens, PD-1 antibody-producing CAR T cells that also produce cytokines like IL-12, IL-15, IL-18, or IL-21 locally in the tumor after engaging a tumor-specific antigen would counteract the highly suppressive environment and synergize the power of the endogenous immune response with the genetically redirected CAR T cell response.