Product-intrinsic NF-κB-driven transcriptional programs connote durability of CAR-T response in multiple myeloma

Idecabtagene vicleucel (ide-cel) induces deep responses in relapsed/refractory multiple myeloma, yet more than half of patients relapse within 1 year. The intrinsic features of chimeric antigen receptor T-cell (CAR-T) products that distinguish durable from nondurable responders are poorly defined, particularly at single-cell resolution, and defining drivers of durable response is critical to guide patient counseling and to inform strategies for optimizing CAR-T manufacturing and efficacy. To address this need, 40 ide-cel infusion products (184 398 cells) were profiled using single-cell RNA sequencing. These analyses revealed that a transcriptional program in CD4 CAR-T cells that led to durable responses is characterized by NF-κB signaling, prosurvival circuits, tonic/chemokine signaling, and elevated CAR transgene expression. These features were associated with prolonged progression-free and overall survival irrespective of baseline clinical characteristics. Further, analyses of paired apheresis and tumor microenvironment samples showed that elevated NF-κB activity is an intrinsic hallmark of T-cell fitness that is characterized by a central memory phenotype and the lack of checkpoint receptor expression, and that these features were manifest in marrow-derived and peripheral blood T cells before CAR-T manufacturing. Finally, validating functional relevance, the pharmacologic inhibition of NF-κB abrogated CAR-T cytotoxicity and cytokine production in vitro. Our results support that NF-κB in the ide-cel product marks a signaling axis affecting CAR-T function and that NF-κB activity represents a global marker of T-cell fitness present before CAR-T manufacture.