Mechanistic modeling predicts efficacy of CISH knockout in tumor-infiltrating lymphocytes with synergistic gene editing

Tumor-infiltrating lymphocyte (TIL) therapy is a type of adoptive cell therapy, where the lymphocytes of a cancer patient's tumor are harvested, expanded<i>in vitro</i>using IL-2 stimulation, and then infused back into the patient Rosenberg and Restifo (2015<i>Science</i><b>348</b>62-68), Bonini and Mondino (2015<i>Eur. J. Immunol.</i><b>45</b>2457-69). However, even with the use of TIL therapy, cancer cells can survive for various reasons, such as poor lymphocyte infiltration into tumors, chronic activation of the T cell receptor and the immunosuppressive tumor microenvironment Morgan<i>et al</i>(1976<i>Science</i><b>193</b>1007-8). Cytokine-inducible SH2-containing (CISH) protein is a negative regulator of T cell activation, and in a recent clinical trial was knocked out in TILs to improve TIL therapy efficacy Rosenberg<i>et al</i>(1985<i>J. Exp. Med.</i><b>161</b>1169-88). A mechanistic signaling pathway model was developed to theoretically evaluate the efficacy of<i>CISH</i>knockout (<i>CISH</i>KO) in T cell activation and examine potential alternative target genes that can theoretically be targeted using multiplex gene-editing or drugs to further improve T cell activation and function Donohue<i>et al</i>(1984<i>J. Immunol.</i><b>132</b>2123-8). Based on the results,<i>CISH</i>knockout increases the transcription of activation biomarkers IL-2 and TNF-<i>α</i>, but also inhibitory biomarkers such as PD1 and FasL. Using global sensitivity analysis, we also found that<i>GSK3B</i>, which is responsible for the deactivation of NFAT, is also predicted to further increase T cell activation when knocked out. In addition, it was predicted that<i>PDCD1, FAS</i>and<i>CTLA4</i>can be knocked out in combination with<i>CISH</i>to further enhance T cell activation and prevent exhaustion and apoptosis.