Combination Immunotherapy with CAR T Cells and Checkpoint Blockade for the Treatment of Solid Tumors

Checkpoint blockade (CPB) therapy can elicit durable clinical responses by reactivating an exhausted immune response. However, response rates remain limited, likely secondary to a lack of a tumor-reactive immune infiltrate. Chimeric antigen receptor (CAR) T cells may provide the necessary tumor-targeting immune infiltrate and a highly specific antitumor immune response. This can be further amplified by the addition of CPB agents, which serve to counteract the immune inhibitory environment undermining optimal CAR T cell efficacy. Herein, we review preclinical and clinical combination therapy with CAR T cells and CPB agents, with a focus on solid tumor malignancies.