Tisagenlecleucel, a CAR T-cell therapy, has been approved as the standard of care for CD19-positive pediatric ALL patients with primary refractory/resistant disease who failed two lines of therapy or those with second or greater relapse (US, Canada, and Europe) and any relapse after HSCT (Canada and Europe only) (8–10). The gene discussed is CD19; the disease is acute lymphoblastic leukemia.