Combination of targeted pharmacotherapy and immunotherapy with anti-CD19 CAR NK cells in acute lymphoblastic leukemia

Anti-CD19 CAR NK cells may provide a promising non-HLA-restricted immune cell product and have been clinically studied primarily on low-grade B-cell lymphoma patients. We used retroviral gene transfer to generate aCD19 CAR NK cells from the peripheral blood of healthy volunteers. We evaluated their efficacy in B-lineage acute lymphoblastic leukemia (BCP-ALL) using patient-derived xenograft (PDX) cells in vitro and in vivo. aCD19 CAR NK cells showed potent specific cytotoxicity against eleven BCP-ALL PDX models in vitro. When used as monotherapy in vivo, they provided a survival benefit, albeit complete remissions were not achieved. Due to the low accumulation of aCD19 CAR NK cells in the bone marrow, we used targeted pharmacotherapy based on venetoclax, dexamethasone, and dasatinib to induce remission in BCR-ABL-positive ALL and combined it with aCD19 NK cell therapy for consolidation. Overlapping therapy enhanced aCD19 CAR NK cell cytotoxicity in vitro and significantly prolonged survival in two high-risk BCP-ALL PDX models with individual long-term remissions. Relapse cells showed no signs of therapy-induced evolution as CD19 expression, sensitivity to venetoclax, and aCD19 CAR cell cytotoxicity remained unchanged. These data demonstrate the potential of aCD19 CAR NK cells as a component of combinatorial therapy for BCP-ALL, which should be further evaluated in clinical trials.