Combining MCL-1 Inhibition and CD37-directed CAR T Cells as an Effective Strategy to Target T-cell Lymphoma

Chimeric antigen receptor (CAR) T cell therapy has not yet been realized for T-cell lymphomas (TCL), partially due to challenges in identifying tumor-specific antigens. We previously reported selective expression of CD37 on malignant T cells in a subset of TCL. Herein, we demonstrate CAR-37 T cells specifically target CD37-positive TCL in part by activating the intrinsic apoptotic pathway. To maximize therapeutic index, we identified selective/targetable BH3 dependences in individual TCL models and combined with CAR-37 T cells. We show that BH3 mimetics do not alter CD37 antigen binding capacity on TCL and have minimal effects on CAR-37 T-cell phenotype or function. In TCL models with dependence on MCL-1, combining CAR-37 T cells and the MCL-1 inhibitor AZD5991 increases anti-TCL response and prolongs survival of xenografted mice. These findings suggest that personalized selection of BH3 mimetic/CAR-T combinations could maximize the therapeutic index for patients with TCL and possibly other diseases. Overall design: Splenic cells were harvested from DFTL-69579 engrafted mice on treatment day 14 from the vehicle and CAR-37 cohorts and on treatment day 15 from the AZD5991 and CAR-37+AZD5991 cohorts within 1 hour of receiving the final AZD5991 dose. Cells were stained with antibodies against human CD45, EGFR, and CD5. Cells were stained with DAPI to gate on viability. Tumor cells were gated as CD45+, CD5+, EGFR-. CART T cells were gated as CD45+, CD5+, EGFR+. Mixed plats/cells were gated as CD45+ and CD5+ and were later differentiated as tumor or CAR T cells during analysis. Single cells were sorted into 96-well plates using a Sony SH800, immediately centrifuged, and stored at -80°C until library preparation.