Abstract 5510: Preclinical study of allogeneic CD19-CAR-DNT cells as an off-the-shelf immunotherapy drug for NHL

Abstract Introduction Allogeneic Double Negative T (DNT, CD3+CD4-CD8-) cells have shown great potential as a novel off-the-shelf immunotherapy drug candidate in clinic trials for r/r/AML patients. This is our first report to demonstrate that CD19-CAR-DNT cells with high percentage of Tscm+Tcm phenotypes have been successfully developed with strong immunotherapeutic effects on Raji-luciferase tumor cells from non-Hodgkin’s lymphoma both in vitro and in vivo. Methods DNT cells were expanded ex vivo from healthy donors and then were transduced with CD19-CAR lentivirus in the presence of IL-2. The CD19-CAR-DNT cell expansions were performed under GMP condition and then harvested and cryo-preserved by CryStor®CS5 in liquid nitrogen for future use. Summary The ex vivo expanded CD19-CAR-DNT cells has more than 50% of Tscm and Tcm phenotypes. The viability and CAR+ percentage of CD19-CAR-DNT cells were 84.40% and 34.98% respectively. The killing of CD19-CAR-DNT cells on Raji-luciferase cells was 77.92% (n=6) at the effector to target ratio of 4:1. Elevated IFN-γ release from CD19-CAR-DNT cells after overnight co-culture with Raji cells was observed. The antitumor efficacy was evaluated in the xenografted NHL mice model. After the first infusion of the cells, the tumor growth inhibitory rates (TGI %) of CD19-CAR-DNT cells at 1×106, 5×106 and 1×107 per mouse on day14 were 80.54%, 98.31% and 99.05% respectively, the killing effects were in a dose-dependent manner. After the second infusion of the CD19-CAR-DNT cells at day 14, median survival times (MST) of the treated three groups mice were elongated till Day60, that is twice longer than that of the xenografted vehicle group. In the subsequent PKPD study, infusion CD19-CAR-DNT cells into Raji-luciferase cell xenografted mice were primarily distributed in lungs, peripheral blood, spleen, and bone marrow within 72h, homing back to liver and spleen on Day36. All animal body weights in both fresh and frozen reconstituted CD19-CAR-DNT cells treated mice were increased with no observed toxicities. Conclusions ex vivo expansion of CD19-CAR-DNT cells were successfully developed to explore its potential as a novel off-the-shelf universal CART drug for malignant B cells leukemia. The cell subsets consist of more than 50% of Tscm and Tcm cells whereas most immunological check point inhibitors were not elevated after priming by target tumor cells except a slight increase of PD-1 molecule. Fresh or frozen CD19-CAR-DNT cells can kill Raji cells in vitro and in vivo studies in a dose-dependent manner although the frozen one showed a delayed killing in vivo. The tumor cells were almost depleted and the MST was significantly increased with NOAEL at 1x107 cells/mouse. The amounts of CD19-CAR-DNT cells are re-distributed from early lungs, peripheral blood to live, spleen later. Citation Format: Liming Yang, Dan Wang, Shangzhi Xu, Liuyang Wang, Jianjun Tong, Honglin Zhu, Man Xu, Xiancai Li, Letu Ji, Chuntao Zheng, Zhiqiang Xiang, Qinghua Sun, Hengcai Wang. Preclinical study of allogeneic CD19-CAR-DNT cells as an off-the-shelf immunotherapy drug for NHL [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5510.