CT-227 Dual CAR-Engineered NK92 Cells: An Off-the-Shelf Cell Therapy for Cancer

Abstract

Autologous chimeric antigen receptor T (CAR-T) cell therapy is an effective treatment for relapsed/refractory acute lymphoblastic leukemia (r/r ALL). However, certain characteristics of autologous CAR-T cells can delay treatment availability. Relapse caused by antigen escape after CAR-T therapy is another issue. Moreover, their therapeutic efficacy against solid tumors is limited. CAR-NK cells have a more favorable toxicity profile compared to CAR T cells, especially in avoiding adverse effects such as cytokine release syndrome and since NK92 cell line can be easily expanded to clinical-grade numbers under current Good Manufacturing Practice (cGMP) conditions, treatment with CAR-modified NK92 should be considered a treatment option for patients with lymphoid and solid malignancies. In an attempt to improve the efficacy of our, already described, NK92/CAR cells against PSMA (prostate-specific membrane antigen), and to prevent some weaknesses in targeting one antigen, such as "on-target off-tumor" cytotoxicity and the tumor escape, we have developed a universal off-the-shelf dual CAR-NK92 cells targeting simultaneously PSMA and prostate stem cell antigen (PSCA), two antigens overexpressed on prostate tumors. To express the Dual CAR system, we used a Lentiviral Vector (LV) carrying a bidirectional promoter that drives the simultaneous expression of the anti-PSMA CAR and the anti-PSCA CAR into NK92 cells. Immune effects, including cytokine release and cytotoxicity of the CAR-NK92 cells against PSMA-PSCA positive prostate cancer cells, were evaluated in vitro. Preclinical study - Outcome measures not used. The CAR-NK92 cells can specifically recognize PSMA+/PSCA+ prostate cancer cells and release cytokines, including IFN-γ, perforin, and granzyme B, and show specific cytotoxicity in vitro. More importantly, we observed a synergistic effect of the dual CAR system in presence of both the antigens. The robust ex vivo expansion of NK92 cells and their exquisite safety profile, as well as the ease of genetic modification, make this cell line an ideal platform for the development of an off-the-shelf therapeutic CAR-engineered variant to target other tumors. Overall, CAR NK-92 cells can be produced at much lower cost compared to CAR T cells and will be a ready-to-use drug, immediately available for cancer patients, with a significant implication for their survival.