FATP2-mediated lipid metabolism enhances chimeric antigen receptor T-cell therapy resistance in B-cell acute lymphoblastic leukemia.

Relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL) remains a leading cause of cancer-related death in children and young adults. While CD19-directed chimeric antigen receptor T cell (CAR-T) therapy offers promise, high rates of long-term failure underscore the need to understand resistance mechanisms. Our studies found p53 inactivation promotes CAR-T resistance in human pre-B-ALL cell lines. Through genome-wide CRISPR/Cas9 screening of CAR-sensitive TP53-wildtype and CAR-resistant TP53-mutated CD19 + B-ALL cell lines, we found the Fatty Acid Transport Protein 2 (FATP2, encoded by SLC27A2) is a leukemia-intrinsic mechanism of CAR-T resistance in TP53-mutant B-ALL. High SLC27A2 expression in pediatric B-ALL patients correlate with worse survival outcomes following conventional chemotherapy. Using B-ALL cell lines and patient-derived xenografts, we show that FATP2-expressing TP53-mutant B-ALL resistance to CAR-T is dependent on exogenous lipid uptake to fuel fatty acid oxidation (FAO) and cell survival, which can be pharmacologically targeted through inhibition of neutral lipolysis and CPT1. These findings identify FATP2-mediated fatty acid uptake and downstream FAO as a potential target to improve existing CAR-T efficacy in human B-ALL.