CD8A and neoplasm: One possibility is that the additive or synergistic effects of KS-58 plus anti-PD-1 are mediated by antitumor immunity and that KS-58 entry into leukocytes disrupts this process, but immunostaining of CT26 tumors revealed that KS-58 did alter effector T-cell (CD8+) tumor infiltration or PD-L1 expression levels.