CD8A and neoplasm: The effects of both CAR T cells and ICB depend on the activation of CD8+ CTLs to kill the tumor, either by bypassing the TCR signal (‘signal 1’) and replacing it with transferred T cells that express a CAR that binds to a tumor-specific cell surface ligand and is fused to activating intracellular signaling domains, or by counteracting inhibitory signals that block T cell costimulation (‘signal 2’).