Abstract 20: KSQ-001EX: An engineered TIL therapy manufactured from a clinical-scale, feeder-free process for the treatment of solid tumor indications

Abstract Tumor Infiltrating Lymphocyte (TIL) therapy is an autologous adoptive cell therapy involving the isolation, ex vivo expansion and infusion of tumor infiltrating lymphocytes (TIL) into late-stage cancer patients for therapeutic benefit. While clinical responses to TIL therapy have been observed in metastatic melanoma, efficacy in other tumor types including non-small cell lung cancer (NSCLC), and head and neck squamous cell carcinoma (HNSCC) [SM1] is limited by the intrinsic functionality and persistence of transferred T cells and the immunosuppressive tumor microenvironment. To improve the clinical outcome of TIL therapy, we have developed KSQ-001EX, an engineered TIL therapy using CRISPR/Cas9 technology to knockout the SOCS1 gene, for the treatment of solid tumors. SOCS1 is a negative regulator of cytokine signaling in T cells that we previously identified as a top target restraining T cell anti-tumor function and persistence using genome-wide in vivo CRISPR screens. To streamline and shorten TIL manufacture, we established a next-generation manufacturing process with resected tumors or core biopsies as starting materials that eliminates the use of feeder cells and REP, shortening the length of manufacture to 22 days. We demonstrated robust manufacture of cryopreserved KSQ-001EX at clinical scale from NSCLC, HNSCC, checkpoint refractory melanoma, and heavily pre-treated colorectal carcinoma (CRC). KSQ-001EX manufactured from clinical-scale runs were highly viable (>90%) following cryopreservation and thaw, with > 90% SOCS1 on-target editing and complete knockdown of SOCS1 at the protein level. Importantly, KSQ-001EX across all indications assessed showed high frequency of CD8 (median ~80%), an attribute associated with TIL clinical responses. KSQ-001EX also retained high diversity of TCR repertoire. Consistent with the biology of SOCS1 editing, KSQ-001EX exhibited greater cytotoxicity and higher IFNγ production against tumor spheroids in comparison to TIL and enhanced induction of pSTAT4 upon IL-12 stimulation, demonstrating heightened sensitivity of KSQ-001EX to cytokines. In conclusion, KSQ-001EX, an engineered TIL therapy with CRISPR/Cas9 mediated inactivation of SOCS1, can be manufactured at clinical doses from surgical resections or core biopsies within 22 days using a simplified feeder-free manufacturing process from multiple indications. KSQ-001EX exhibits heightened anti-tumor activity in preclinical models, with therapeutic benefit to be evaluated in a planned clinical trial in patients with treatment-refractory melanoma, NSCLC, and HNSCC. [SM1]Spell out these at first instance? Citation Format: Sharon Lin, Gustavo Martinez, Marie-Andrée Forget, Katrina Adlerz, Mitali Ghose, Leila Williams, Paul Dunbar, Frank Thompson, Fiona Sharp, Hugh Gannon, Conor Calnan, Ashish Yeri, Dipen Sangurdekar, Donald Sakellariou-Thompson, Samantha Fix, Tamara Griffith, Ellie Jafari, Jane Zulovich, Priya Balasubramanian, Erin Willert, MIcah Benson, Chantale Bernatchez, Karrie Ka Wai Wong. KSQ-001EX: An engineered TIL therapy manufactured from a clinical-scale, feeder-free process for the treatment of solid tumor indications [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 20.