The first clinical trial using the revolutionary CRISPR/Cas9 technique for cancer treatment recruited its first patient in West China Hospital, Sichuan University in 2016.265 In this nonrandomized, open-label phase I study (NCT02793856), the safety of ex vivo engineered PD-1 knockout T cells has been evaluated in the treatment for metastatic non-small cell lung cancer with progression after all standard treatments. The gene discussed is SNCA; the disease is cancer.