Abstract 6593: PRGN-3005 UltraCAR-T™: multigenic CAR-T cells generated using non-viral gene delivery and rapid manufacturing process for the treatment of ovarian cancer (2020)

Abstract Ovarian cancer is the most lethal of gynecologic cancers. Chimeric antigen receptor (CAR)-T cells have improved clinical outcomes in hematological malignancies; however similar responses have not yet been achieved for solid tumors. Furthermore, traditional methods for CAR-T manufacturing utilize viral vectors and weeks of ex vivo expansion to achieve clinically relevant cell numbers. This leads to CAR-T cells with an exhausted T cell phenotype, high manufacturing costs, and treatment delays. We have developed the UltraCAR-T™ platform to overcome these limitations by utilizing an advanced non-viral gene delivery system and a rapid, decentralized manufacturing process. Our non-viral gene delivery platform is based on Sleeping Beauty transposon system precision engineered for optimal delivery of multiple genes of UltraCAR-T. UltraCAR-T cells are manufactured at medical center's cGMP facility using autologous T cells and administered back to patient only one day after gene transfer. PRGN-3005 UltraCAR-T cells simultaneously co-express (i) a CAR specifically targeting MUC16 which is highly expressed on ovarian tumors with limited normal tissue expression; (ii) membrane bound IL-15 (mbIL15) for enhanced in vivo expansion and persistence; and (iii) a kill switch for improved therapeutic control. Healthy donor T cells were transfected with non-viral system encoding CAR, mbIL15 and kill switch to generate PRGN-3005 cells. Expression of transgenes was confirmed by flow cytometry and western blot analyses. PRGN-3005 demonstrated a robust MUC16-specific cytotoxicity of ovarian cancer cells in vitro. PRGN-3005 exhibited a stem-cell like memory phenotype, significant improvement in survival even in absence of exogenous cytokines and lacked autonomous proliferation in vitro in the absence of MUC16 compared to conventional CAR-T cells, demonstrating beneficial effects of mbIL15 on phenotype and persistence of UltraCAR-T cells. Furthermore, we demonstrated that PRGN-3005 cells were selectively and effectively eliminated by kill switch activator antibody via ADCC. For in vivo anti-tumor efficacy of PRGN-3005, an ovarian cancer model of MUC16+ SK-OV-3 cell line was evaluated in NSG mice. In tumor-bearing mice, a single administration of PRGN-3005 one day after gene transfer resulted rapid in vivo expansion and significant increase in UltraCAR-T cells, in particular T stem cell memory (TSCM) population compared to mbIL15neg CAR-T cells. PRGN-3005 demonstrated significantly higher anti-tumor effect (p&amp;lt;0.01) compared to mbIL15neg CAR-T and led to complete tumor regression in all treated mice. PRGN-3005 UltraCAR-T administered one day after non-viral gene transfer has superior anti-tumor efficacy and persistence compared traditional CAR-T cells and represent a promising opportunity for ovarian cancer treatment. Based on these results, FDA has approved an IND application and the first in human PRGN-3005 Phase I clinical trial for advanced ovarian cancer is currently under evaluation (NCT03907527). Citation Format: Tim Chan, Marion Chakiath, Lindsey Shepard, Simon Metenou, Fernando Carvajal-Borda, Jose Velez, Adeline Govekung, Jacques Plummer, Carol Poortman, Padma Kamineny, Xiaohong Ma, Rutul R. Shah, Mary L. Disis, Helen Sabzevari. PRGN-3005 UltraCAR-T™: multigenic CAR-T cells generated using non-viral gene delivery and rapid manufacturing process for the treatment of ovarian cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6593.