Abstract 38: AB-2100, a PSMA-inducible CA9-specific CAR T cell product for the treatment of ccRCC provides long-term tumor responses in preclinical mouse model

Abstract Common challenges of CAR-T cell therapies in solid tumors, such as clear cell renal cell carcinoma (ccRCC), include insufficient therapeutic potency and lack of tumor specificity. We have developed AB-2100, an autologous integrated circuit T (ICT) cell product, generated via CRISPR-mediated knock-in of a single transgene into a safe-harbor locus. AB-2100 encodes a transcriptionally regulated sequential AND gate that comprises a priming receptor (PrimeR) specific for PSMA and an inducible CAR targeting CA9 antigen, which is widely expressed on local and metastatic lesions. AB-2100’s sequential AND logic-gate confers tumor-specific activity by priming off of PSMA-expressing tumor vasculature to induce CA9 CAR expression. This unique feature of the logic gate is intended to increase the safety profile of AB-2100 given that PSMA and CA9 are predicted to have limited co-expression in normal tissues. Additional functionality includes short-hairpin RNAs (shRNA) against Fas and TGFBR designed to prevent tumor-mediated resistance, and a synthetic pathway activator (SPA) that drives constitutive STAT3 signaling and enhanced T cell cytotoxicity and expansion. Mechanism of action studies demonstrate that AB-2100 can prime off of PSMA-expressing endothelial cells and induce tumor-specific killing of CA9 tumor cells, leading to the eradication of ccRCC targets in vitro. AB-2100 also exhibited selective killing of dual antigen expressing tumors in vivo using a dual-flank subcutaneous xenograft model. Preclinical xenograft studies also demonstrated that TGFBR shRNA and SPA modules enhanced antitumor activity of ICTs. When AB-2100 potency was evaluated in the subcutaneous A498 xenograft model, treatment with AB-2100 resulted in complete and durable anti-tumor responses. In summary, preclinical data demonstrate that AB-2100 selectively targets tumors co-expressing PSMA and CA9, and can overcome multiple suppressive mechanisms in the tumor microenvironment. These results support the evaluation of AB-2100 in the clinic for the treatment of advanced or metastatic ccRCC. Citation Format: Suchismita Mohanty, Jeremy Chen, Alma Gomez, Angela Boroughs, Irene Scarfo, Laura Lim, Kevin Dang, Marvin Chew, Rakesh Sudhakah, Michelle Nguyen, Thomas J. Gardner, Beatriz Millare, James Zhang, Darrian Moskowitz, Stanley Zhou, Neroli H. Xie, Nickolas Attanasio, Amanda Fearon, Ivan Chan, Vibhavari Sail, Vince Thomas, Jennesa Smith, Jennifer McDevitt, Levi Gray-Rupp, Alba Gonzalez, Christopher Murriel, W. Nicholas Haining. AB-2100, a PSMA-inducible CA9-specific CAR T cell product for the treatment of ccRCC provides long-term tumor responses in preclinical mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 38.