Abstract LB027: Adoptive cell therapy with genetically engineered T cells for epithelial ovarian cancer

Abstract The limited clinical benefits of immunotherapy in epithelial ovarian cancer (EOC) highlight the urgent need for innovative treatment strategies to improve outcomes. This study employs a dual-pronged strategy to promote EOC immunotherapy, focusing on tumor-specific T-cell receptor (TCR)-redirected T cells. Cancer cells derived from the ascites of EOC patients were analyzed to determine the expression of selected tumor-associated antigens (Mesothelin, HER2, NY-ESO-1, and WT1) and membrane-bound inhibitory receptor (IR) ligands. These antigens, critical for tumor progression, were selected as targets for our T cell products. Using TCR gene editing techniques, T cells with HLA-A*02:01-restricted receptors specific for these antigens were generated, drawing from both our laboratory’s library and relevant literature. In clinically relevant models using patient ascites-derived primary cultures (PC), T cells engineered with WT1-, MSLN-, and NY-ESO-1-specific TCRs exhibited potent and specific elimination of target cells, with WT1-TCR emerging as the most promising candidate for further development. We hypothesized that disrupting IR pathways could shield engineered T cells from immunosuppression within the tumor microenvironment (TME), thereby enhancing their therapeutic efficacy. To explore this, T-cell products were engineered to express WT1-TCR while incorporating gene disruptions of specific IRs (TIM3 or LAG3) (IRKO WT1-TCR). To assess the impact of IR disruption on anti-tumor efficacy, WT1-TCR and IRKO WT1-TCR T cells were tested against WT1-positive, HLA-A*02:01-positive PC and tumor organoids (PDOs). Evaluations included cytokine secretion, T cell activation using flow cytometry, and apoptosis measured via Incucyte live cell imaging. IRKO WT1-TCR T cells demonstrated superior cytotoxicity compared to WT1-TCR T cells, with TIM3KO WT1-TCR showing heightened effectiveness against tumor cells expressing TIM3 ligands. Co-culture experiments with PDOs further confirmed the increased induction of apoptosis mediated by TIM3KO and LAG3KO WT1-TCR T cells compared to their IR-competent counterparts. Finally, in vivo experiments were conducted to monitor tumor growth using IVIS live imaging and ultrasound. Considering the results of in vitro experiments, our primary focus was to analyze the efficacy of TIM3KO WT1-TCR T cells in comparison to IRCOMPETENT WT1-TCR T cells. Both T cell products significantly inhibited tumor growth compared to control groups that received no T cell therapy. Ultrasound imaging revealed a reduction in the size of abdominal masses, with TIM3KO WT1-TCR treatment achieving the most pronounced decrease in mass diameter, particularly in the intermediate size range (4-8 mm). These findings support the hypothesis that TIM3 knockout enhances the anti-tumor efficacy of WT1-TCR-engineered T cells for EOC. Citation Format: Maria Chiara Maffia, Eliana Ruggiero, Elena Tassi, Anna Simioni, Zulma Magnani, Alice Bergamini, Giorgia Mangili, Giorgio Candotti, Luca Bocciolone, Giacomo Pavone, Massimo Candiani, Miriam Sant’Angelo, Claudio Doglioni, Birgit Schultes, Aaron Prodeus, Chiara Bonini. Adoptive cell therapy with genetically engineered T cells for epithelial ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB027.