The “Phase I/II Trial in Patients with Metastatic Gastrointestinal Epithelial Cancer Administering Tumor-Infiltrating Lymphocytes in which the Gene Encoding CISH was Inactivated using the CRISPR/Cas9 System” (NCT04426669) is one of the pioneers in this type of study, which is a clinical trial to evaluate the safety and efficacy of genetically modified neoantigen-specific tumor-infiltrating lymphocytes (TILs), in which the intracellular immune checkpoint CISH (cytokine-induced SH2 protein) will be inhibited using CRISPR/Cas9 gene editing for the treatment of gastrointestinal (GI) cancer [68]. The gene discussed is CISH; the disease is neoplasm.