Rational design of a SOCS1-edited tumor infiltrating lymphocyte therapy for solid tumors using CRISPR/Cas9 screens [TIL5746_human_invitro]
Tumor Infiltrating Lymphocyte (TIL) therapy have shown promise  in the treatment of patients with refractory solid tumors, with improvement in response rates and durability of responses nevertheless sought.  To identify targets capable of enhancing the anti-tumor activity  of T cell therapies, large-scale in vitro and in vivo CRISPR/Cas9 screens were performed, with the suppressor of cytokine signaling 1 (SOCS1) gene identified as a top T cell-enhancing target.  In murine CD8 T cell therapy models, SOCS1 served as a critical checkpoint in restraining the accumulation of T central memory cells in lymphoid organs as well as intermediate (Texint) and effector (Texeff) exhausted T cell subsets derived from progenitor exhausted T cell (Texprog) cells in tumors. A comprehensive CRISPR tiling screen of the SOCS1 coding region identified sgRNAs targeting the SH2 domain of SOCS1 as the most potent, with a sgRNA with minimal off-target cut sites used to manufacture KSQ-001, an engineered TIL therapy with SOCS1 inactivated by CRISPR/Cas9.  KSQ-001 possessed increased responsiveness to cytokine signals and enhanced in vivo anti-tumor function in mouse models. These data demonstrate the use of CRISPR/Cas9 screens in the rational design of T cell therapies. Overall design: A large-scale in vitro CRISPR/Cas9 screen was performed to identify targets that can enhance TIL function. A barcoded sgRNA library encompassing a curated list of 5137 genes involved in T cell function, all predicted cell surface receptors (CSRs), and genes found to be expressed within immune cells and peripheral blood was introduced by lentiviral transduction into pre-REP TIL together with Cas9.  Engineered sgRNA Lib+ TIL were then expanded under REP conditions. One input population of transferred T cells was sequenced and endpoint T cells were collected at day 17 and sequenced.