Feasibility and preclinical efficacy of CD7-unedited CD7 CAR T cells for T cell malignancies

• Published in: Molecular therapy 2023-01, Vol.31 (1), p.24-34
• Main Authors: Watanabe, Norihiro, Mo, Feiyan, Zheng, Rong, Ma, Royce, Bray, Vanesa C., van Leeuwen, Dayenne G., Sritabal-Ramirez, Juntima, Hu, Hongxiang, Wang, Sha, Mehta, Birju, Srinivasan, Madhuwanti, Scherer, Lauren D., Zhang, Huimin, Thakkar, Sachin G., Hill, LaQuisa C., Heslop, Helen E., Cheng, Chonghui, Brenner, Malcolm K., Mamonkin, Maksim
• Format: Article
• Language: English
• Subjects: adoptive cell therapy; Animals; CD7; chimeric antigen receptor; Dasatinib - metabolism; engineered T cells; Feasibility Studies; fratricide; Humans; Immunotherapy, Adoptive - methods; Mice; Original; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Receptors, Chimeric Antigen - genetics; Receptors, Chimeric Antigen - metabolism; T cell lymphoma; T cell malignancies; T-ALL; T-Lymphocytes
• ISSN: 1525-0016; 1525-0024
• DOI: 10.1016/j.ymthe.2022.09.003

Chimeric antigen receptor (CAR)-mediated targeting of T lineage antigens for the therapy of blood malignancies is frequently complicated by self-targeting of CAR T cells or their excessive differentiation driven by constant CAR signaling. Expression of CARs targeting CD7, a pan-T cell antigen highly expressed in T cell malignancies and some myeloid leukemias, produces robust fratricide and often requires additional mitigation strategies, such as CD7 gene editing. In this study, we show fratricide of CD7 CAR T cells can be fully prevented using ibrutinib and dasatinib, the pharmacologic inhibitors of key CAR/CD3ζ signaling kinases. Supplementation with ibrutinib and dasatinib rescued the ex vivo expansion of unedited CD7 CAR T cells and allowed regaining full CAR-mediated cytotoxicity in vitro and in vivo on withdrawal of the inhibitors. The unedited CD7 CAR T cells persisted long term and mediated sustained anti-leukemic activity in two mouse xenograft models of human T cell acute lymphoblastic leukemia (T-ALL) by self-selecting for CD7−, fratricide-resistant CD7 CAR T cells that were transcriptionally similar to control CD7-edited CD7 CAR T cells. Finally, we showed feasibility of cGMP manufacturing of unedited autologous CD7 CAR T cells for patients with CD7+ malignancies and initiated a phase I clinical trial (ClinicalTrials.gov: NCT03690011) using this approach. These results indicate pharmacologic inhibition of CAR signaling enables generating functional CD7 CAR T cells without additional engineering. [Display omitted] Mamonkin and colleagues demonstrate CAR-mediated fratricide in T cells can be effectively minimized ex vivo by reversible pharmacologic inhibition of CAR signaling kinases. Removal of the inhibitors restores T cell cytotoxicity and enables selection for a fratricide-resistant CAR T cell population with potent anti-tumor activity in vivo.