A PD-1KO anti-CD19 CAR T cell therapy has been evaluated in a Phase I clinical trial for relapsed/refractory B cell non-Hodgkin lymphoma, demonstrating improved preclinical survival and extended in vivo efficacy compared to PD-1–intact CAR T cells, thereby supporting the clinical feasibility of PD-1KO in engineered cell products.63 The gene discussed is PDCD1; the disease is B-cell non-Hodgkin lymphoma.