Abstract 1768: Multiplexed shRNA cassettes targeting orthogonal pathways (FAS/PTPN2/TGFBR) enhance the potency of integrated circuit T cells (ICTs) in multiple solid tumor models

• Published in: Cancer research (Chicago, Ill.) Vol. 83; no. 7_Supplement; p. 1768
• Main Authors: Gardner, Thomas J., Litterman, Adam, Singh, Brenal K., Silva, Luisa, Hari, Mukund, Zhou, Stanley, Tang, Colin, Joshi, Sahil, Gagnon, John, Takacsi-Nagy, Oliver, Hall, Jason, Pope, Hans, Zhang, James, Gomez, Alma, Chen, Jeremy, Mohanty, Suchismita, Thomas, Vince, Quant, Nicholas, Millare, Beatriz, Casbon, Amy-Jo, Bezman, Natalie, Gray-Rupp, Levi, Boroughs, Angela C., Haining, W. Nicholas
• Format: Journal Article
• Language: English
• Published: 04.04.2023
• ISSN: 1538-7445; 1538-7445
• DOI: 10.1158/1538-7445.AM2023-1768

Abstract T cell exhaustion resulting from chronic antigen stimulation and immunosuppression in the tumor microenvironment (TME) limits CAR T efficacy in the solid tumor setting. We have previously shown that engineering therapeutic T cell products using CRISPR-based gene insertion of a dual shRNA cassette targeting Fas and PTPN2 significantly increased antitumor efficacy of Integrated Circuit T cells (ICTs) in ovarian cancer models. We sought to build on this finding to induce additional gene perturbations that improve the efficacy of ICTs. Transforming growth factor (TGF)-b is an immunosuppressive cytokine that potently inhibits T cell responses and is present at high levels in numerous solid tumors, including renal cell carcinoma (RCC). In order to render ICT cells less susceptible to TGF-b-mediated suppression, we developed a quadruple shRNA cassette that simultaneously targets Fas, PTPN2, and TGFBR. Candidate TGFBR-targeting shRNAs were selected for their ability to reduce surface TGFBR receptor expression and impair proximal (pSMAD) or distal (CD103, PD-1) signaling through TGFBR. While single shRNAs against TGFBR did not rescue ICT cell activity in the presence of TGF-b, likely due to partial knockdown of TGFBR signaling, a cassette encoding two shRNAs against TGFBR restored ICT function to similar levels observed in the absence of TGF-b. The quadruple shRNA cassettes targeting Fas/PTPN2/TGFBR significantly enhanced antitumor activity of ICT cells in multiple xenograft tumor models relative to Fas/PTPN2 cassettes. These results demonstrate the utility of multiplexed shRNA strategies to render therapeutic T cells resistant to orthogonal suppressive pathways in solid tumors. Citation Format: Thomas J. Gardner, Adam Litterman, Brenal K. Singh, Luisa Silva, Mukund Hari, Stanley Zhou, Colin Tang, Sahil Joshi, John Gagnon, Oliver Takacsi-Nagy, Jason Hall, Hans Pope, James Zhang, Alma Gomez, Jeremy Chen, Suchismita Mohanty, Vince Thomas, Nicholas Quant, Beatriz Millare, Amy-Jo Casbon, Natalie Bezman, Levi Gray-Rupp, Angela C. Boroughs, W. Nicholas Haining. Multiplexed shRNA cassettes targeting orthogonal pathways (FAS/PTPN2/TGFBR) enhance the potency of integrated circuit T cells (ICTs) in multiple solid tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1768.