No abstract

Key Points Genomic disruption of CD7 prior to CAR transduction allows generation of CD7 CAR T cells without extensive self-antigen-driven fratricide. CD7 CAR T cells have robust activity against T-cell malignancies in vitro and in vivo.

Summary Antigen-independent tonic signaling by chimeric antigen receptors (CARs) can increase differentiation and exhaustion of T cells, limiting their potency. Incorporating 4-1BB costimulation in CARs may enable T cells to resist this functional exhaustion; however, the potential ramifications of tonic 4-1BB signaling in CAR T cells remain unclear. Here, we found that tonic CAR-derived 4-1BB signaling can produce toxicity in T cells via continuous TRAF2-dependent activation of the NF-kB pathway and augmented Fas-dependent cell death. This mechanism was amplified in a non-self-inactivating gammaretroviral vector through positive feedback on the LTR promoter, further enhancing CAR expression and tonic signaling. Attenuating CAR expression by substitution with a self-inactivating lentiviral vector minimized tonic signaling and improved T-cell expansion and anti-tumor function. These studies illuminate the interaction between tonic CAR signaling and the chosen expression platform and identify inhibitory properties of the 4-1BB costimulatory domain that have direct implications for rational CAR design.

Key Points T cells transduced with a CD5 CAR demonstrate limited and transient fratricide and expand ex vivo. CD5 CAR T cells eliminate T-ALL blasts in vitro and control disease progression in xenograft T-ALL mouse models.