PDCD1 and cancer: The trial involved the CRISPR/Cas9-based deletion of the genes encoding TCRα, TCRβ and programmed cell death protein 1 (PD-1; PDCD1), in T cells derived from patients, followed by lentiviral transduction of a transgenic TCR specific for the cancer antigen New York oesophageal squamous cell carcinoma 1 (NY-ESO-1).