CD8A and neoplasm: Furthermore, since we have previously observed increased expression of PD-1 on tumor-infiltrating CD8+ T cells following α-4-1BB/α-OX-40 treatment, we next investigated the efficacy of combining MEKi with both an agonist immunotherapy regimen (α-4-1BB/α-OX-40) and blockade with α-PD-1 antibody.