Karlsson H, Karlsson SC, Lindqvist AC, Fransson M, Paul-Wetterberg G, Nilsson B, Essand M, Nilsson K, Frisk P, Jernberg-Wiklund H, Loskog A, Loskog SI
Cancer Gene Ther. 20 (7) 386-393 [2013-07-00; online 2013-06-21]
B-cell malignancies upregulate the B-cell lymphoma 2 (Bcl-2) family inhibitors of the intrinsic apoptosis pathway, making them therapy resistant. However, small-molecule inhibitors of Bcl-2 family members such as ABT-737 restore a functional apoptosis pathway in cancer cells, and its oral analog ABT-263 (Navitoclax) has entered clinical trials. Gene engineered chimeric antigen receptor (CAR) T cells also show promise in B-cell malignancy, and as they induce apoptosis via the extrinsic pathway, we hypothesized that small-molecule inhibitors of the Bcl-2 family may potentiate the efficacy of CAR T cells by engaging both apoptosis pathways. CAR T cells targeting CD19 were generated from healthy donors as well as from pre-B-ALL (precursor-B acute lymphoblastic leukemia) patients and tested together with ABT-737 to evaluate apoptosis induction in five B-cell tumor cell lines. The CAR T cells were effective even if the cell lines exhibited different apoptosis resistance profiles, as shown by analyzing the expression of apoptosis inhibitors by PCR and western blot. When combining T-cell and ABT-737 therapy simultaneously, or with ABT-737 as a presensitizer, tumor cell apoptosis was significantly increased. In conclusion, the apoptosis inducer ABT-737 enhanced the efficacy of CAR T cells and could be an interesting drug candidate to potentiate T-cell therapy.