Developing a Dual-Targeting CD33/CD70 CAR T-Cell Strategy Against Acute Myeloid Leukemia to Overcome Tumor Heterogeneity.

backgroundAcute myeloid leukemia (AML) remains the deadliest form of leukemia in children and adults despite therapeutic advances in recent decades. Chimeric antigen receptor (CAR) T-cell therapy is one such therapeutic approach that has been explored preclinically and clinically in AML; however, its efficacy is limited by antigen heterogeneity. To overcome this roadblock, we propose a dual-targeting CAR T-cell strategy, targeting the AML-associated antigens CD33 and CD70.

methodsTo recapitulate tumor heterogeneity, we genetically edited the AML cell line Molm-13 using CRISPR-Cas9 to generate distinct sublines, namely CD33+/CD70-, CD33-/CD70+, and CD33+/CD70+. Two dual-targeting CAR T-cell approaches were developed: a "pooled" product, in which CAR T cells directed towards CD33 or CD70 are combined and co-administered, and a "co-transduced" product, wherein one population of T cells is transduced with both CD33-CAR- and CD70-CAR-encoding viral vectors.

resultsPooled and co-transduced products demonstrated potent cytotoxicity against all Molm-13 populations, whereas single-antigen CAR approaches were not as effective when their respective target antigen was absent. Mice engrafted with CD33/CD70 heterogeneous Molm-13 cells were treated with pooled or co-transduced CD33/CD70 CAR T cells. Both groups exhibited a significant survival advantage over the untreated group, with the co-transduced approach showing a statistically significant advantage over the pooled group.

conclusionsIn summary, engineering one T cell to express both CARs yielded superior cytotoxicity when targeting a heterogeneous AML blast population.