PT - JOURNAL ARTICLE AU - Santoro, Stephen AU - Cooper, Aaron AU - Bezman, Natalie AU - Feng, Jun AU - Chawla, Kanika AU - Williams, Jaspar AU - Gagnon, John AU - Hall, Jason AU - Polyak, Dina AU - Boroughs, Angela AU - Nguyen, Michelle AU - Mohanty, Suchismita AU - Litterman, Adam AU - Granja, Jeff AU - DeTomaso, David AU - Zheng, Grace AU - Smith, Jenessa AU - LeFace, Drake AU - Mikkelsen, Tarjei AU - Jun, Susie TI - 213 AB-X integrated circuit T cells demonstrate improved potency, expansion, and specificity compared to MSLN CAR T cells AID - 10.1136/jitc-2021-SITC2021.213 DP - 2021 Nov 01 TA - Journal for ImmunoTherapy of Cancer PG - A226--A226 VI - 9 IP - Suppl 2 4099 - http://jitc.bmj.com/content/9/Suppl_2/A226.short 4100 - http://jitc.bmj.com/content/9/Suppl_2/A226.full SO - J Immunother Cancer2021 Nov 01; 9 AB - Background In solid tumors, CAR T cell efficacy is limited by off-tumor toxicity and suppression by the tumor microenvironment (TME). AB-X is an integrated circuit T cell (ICT cell) intended for the treatment of ovarian cancer. AB-X includes a transgene cassette with two functional modules: 1) an ”AND” logic gate designed to limit off-tumor toxicity through dual tumor antigen recognition; 2) a dual shRNA-miR to resist TME suppression and improve ICT cell function. The AB-X logic gate consists of a priming receptor that induces expression of an anti-mesothelin (MSLN) CAR upon engagement of a ALPG/P (alkaline phosphatase germ-line/placental). The dual shRNA-miR mediates downregulation of FAS and PTPN2. The AB-X DNA cassette is inserted into the T cell genome at a defined novel genomic site via CRISPR-based gene editing.Methods Dual-antigen specificity of the logic gate was assessed in mice harboring MSLN+ and ALPG/P+MSLN+ K562 tumors established on contralateral flanks. Potency was measured in a subcutaneous MSTO xenograft model. Logic-gated ICT cells were compared with MSLN CAR T cells in both models. In vitro, expansion of ICT cells with the FAS/PTPN2 shRNA-miR was evaluated in a 14 day repetitive stimulation assay (RSA). In vivo, expansion and potency were measured in the MSTO xenograft model. An in vitro FAS cross-linking assay was conducted to assess the impact of FAS knockdown on FAS-mediated apoptosis.Results Logic-gated ICT cells demonstrated specific activity against ALPG/P+MSLN+ tumors, but had no effect against MSLN+ tumors in the K562 in vivo specificity model. In addition, logic-gated ICT cells demonstrated greater in vivo potency than MSLN CAR T cells in the MSTO xenograft model. In our RSA, ICT cells containing the FAS/PTPN2 shRNA-miR had 8-fold greater expansion than the MSLN CAR T cells. Enhanced expansion was confirmed in vivo with ICT cells demonstrating >10-fold expansion in tumors and peripheral blood, enabling comparable growth inhibition in MSTO xenografts at less than one quarter the dose of the MSLN CAR T cells. Importantly, PTPN2 knockdown resulted in balanced expansion of all T cell subsets, including CD45RA+, CCR7+ memory cells. Lastly, ICT cells containing the FAS/PTPN2 shRNA-miR were resistant to FAS-mediated apoptosis.Conclusions AB-X ICT cells specifically recognize ALPG/P+MSLN+ tumors, demonstrate superior potency, expansion, and persistence compared with MSLN CAR T cells, and are resistant to ovarian TME suppression. AB-X will be evaluated in clinical trials for treatment of platinum resistant/refractory ovarian cancer.Acknowledgements We would like to acknowledge all of our colleagues at Arsenal Biosciences, without whom this work would not have been possible.