The concept of immune checkpoint knockout in redirected T cells has been demonstrated in vitro and in vivo, both for tTCR-T cells74 and CAR-T cells.75, 76, 77, 78, 79 Improved antitumor reactivity of redirected T cells after PD-1 disruption was observed in a range of preclinical cancer models, for example, models of melanoma,74 hepatocellular carcinoma,75 glioma,76,79 breast cancer,77 and erytroleukemia.78 The gene discussed is PDCD1; the disease is melanoma.