Abstract B080: AB-1015, an Integrated Circuit T (ICT) cell therapy containing an ALPG/MSLN logic gate and FAS/PTPN2 shRNA-miR, for the treatment of ovarian cancer

Abstract CAR T cell activity in solid tumors is limited by off-tumor toxicity and functional suppression from the tumor microenvironment (TME). To address these challenges, we have developed AB-1015, an autologous ICT cell product intended for use in ovarian cancer. AB-1015 incorporates two functional modules: an” AND” logic gate designed to limit off-tumor toxicity through dual tumor antigen recognition, and a dual shRNA-miR targeting FAS and PTPN2 to resist TME suppression and to improve ICT cell function. The AB-1015 logic gate consists of a priming receptor (PrimeR) against ALPG/P and an inducible anti-MSLN CAR that is upregulated upon PrimeR engagement. At basal state, only a small percentage of AB-1015 cells have detectable CAR present at low MFI. The percentage of AB-1015 cells that express CAR, as well as the CAR MFI, increase in response to increasing levels of ALPG. This unique feature of the logic gate aims to increase the tumor specificity of AB-1015, given that ALPG/P and MSLN are not co-expressed in the normal tissues. To functionally test the dual-antigen specificity, AB-1015 cells were co-cultured with K562 cells engineered with only one target antigen (ALPG or MSLN), both antigens (ALPG and MSLN), or neither antigen. AB-1015 demonstrated potent killing of K562-ALPG/MSLN cells, and minimal activity against K562 cells expressing only MSLN. In addition, AB-1015 showed over 100-fold increase in IFNg production when co-cultured with K562-ALPG/MSLN cells, compared to co-culture with K562-MSLN cells that do not express ALPG. The dual-antigen specificity of the logic gate was further assessed in vivo using a dual flank tumor xenograft model where one tumor expressed both ALPG and MSLN, and the contralateral tumor expressed MSLN alone. Compared with the RNP group, the constitutive anti-MSLN CAR demonstrated tumor reduction on both flanks. In contrast, the activity of AB-1015 was specific to the ALPG+MSLN+ tumor. The anti-tumor activity of AB-1015 was established in an intraperitoneal OVCAR3 ovarian xenograft model that resembles high-grade serous ovarian cancer histology. AB-1015 demonstrated potent anti-tumor activity as demonstrated by a decrease in bioluminescent signal from the tumors treated with AB-1015. To further increase the stringency of our preclinical models, we engineered the subcutaneous MSTO xenograft model to express FASL. In this model, conventional anti-MSLN CAR T cells failed to control tumor outgrowth. In contrast, AB-1015 resists FASL suppression via knockdown of FAS on the ICT surface. As a result, AB-1015 is capable of completely clearing these otherwise difficult-to-treat tumors in this model. In summary, maximal AB-1015 effector function depends on PrimeR engagement with ALPG/P and CAR binding to MSLN. AB-1015 demonstrates superior potency compared with conventional anti-MSLN CAR T cells and is resistant to ovarian TME suppression in preclinical studies. Based on these promising preclinical data, AB-1015 is being studied in a phase I clinical trial (NCT05617755) for patients with platinum-resistant ovarian cancer. Citation Format: Jun Feng, Jasper Williams, Hongruo Yun, Dina Polyak, James Zhang, Michelle Nguyen, Irene Scarfo, Jessica Fuhriman, Aaron Cooper, Jennifer McDevitt, Stephen Santoro. AB-1015, an Integrated Circuit T (ICT) cell therapy containing an ALPG/MSLN logic gate and FAS/PTPN2 shRNA-miR, for the treatment of ovarian cancer abstract. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84 (5 Suppl₂): Abstract nr B080.