Abstract 2175: KSQ-001: A CRISPR/Cas9-engineered tumor infiltrating lymphocyte (eTILTM) therapy for solid tumors
Authors: Schlabach Mike , Colletti Nick , Hohmann Anja , Wrocklage Christopher , Gannon Hugh , Falla Alejandra , Tubo Noah , LaMothe Robert A. , Bullock Caroline , Mitchell Pete T. , Hafeez Nafeeza , Sathithloetsakun Suphinya , Grasberger Paula E. , Le Mercier Isabelle , Garrett Tracy E. , Keegan Sean , Shenker Sol , Franco Charlotte , Stegmeier Frank , Kryukov Gregory V. , Cadzow Louise , Benson Micah 
Published: September 2020

Abstract
Adoptive cell therapy (ACT) with ex vivo expanded tumor infiltrating lymphocytes (TIL) offers a potentially transformative treatment for treatment refractory solid tumors. However, the immunosuppressive tumor microenvironment (TME) limits the effectiveness of TIL therapy. To systematically identify targets that have the potential to improve T-cell function in the TME, we conducted two genome-wide CRISPR/Cas9 functional screens of immune cells using our proprietary CRISPRomics® platform. The first screen employed primary mouse T cells and assessed in vivo T cell infiltration into tumors by measuring sgRNA guide enrichment. Notably, this screen identified clinically active targets, such as PD-1, and identified multiple targets, including Cell Therapy-1 (CT-1), that demonstrated anti-tumor T-cell function superior to PD-1. The potential of inactivating CT-1 for ACT was subsequently validated in both PD-1 sensitive and insensitive syngeneic tumor models in the absence of any additional conditioning regimens. CT-1 edited T cells established durable anti-tumor memory characterized by a T central memory state. A second genome-wide screen employed human TIL and assessed the impact of gene inactivation on human TIL expansion under standard manufacturing conditions. This screen also identified CT-1 as a top target. We therefore prioritized the development of KSQ-001, an engineered TIL (eTILTM) therapy, created via CRISPR/Cas9-mediated editing of CT-1. Potent and selective sgRNAs targeting CT-1 were identified and characterized, and manufacturing methods to engineer human TIL with high efficiency have been developed. Together, these data demonstrate that our CRISPRomics® platform enables comprehensive target identification and validation of compelling new targets for the development of robust eTILTM therapies, and support the clinical evaluation of KSQ-001 as a next generation adoptive cell therapy in a variety of treatment-refractory solid tumors.
Citation Format: Mike Schlabach, Nick Colletti, Anja Hohmann, Christopher Wrocklage, Hugh Gannon, Alejandra Falla, Noah Tubo, Robert A. LaMothe, Caroline Bullock, Pete T. Mitchell, Nafeeza Hafeez, Suphinya Sathithloetsakun, Paula E. Grasberger, Isabelle Le Mercier, Tracy E. Garrett, Sean Keegan, Sol Shenker, Charlotte Franco, Frank Stegmeier, Gregory V. Kryukov, Louise Cadzow, Micah Benson. KSQ-001: A CRISPR/Cas9-engineered tumor infiltrating lymphocyte (eTILTM) therapy for solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2175.