Chimeric antigen receptor (CAR) T-cell immunotherapy has shown tremendous success in the treatment of acute lymphocytic leukemia (ALL) and refractory diffuse large B-cell lymphoma (DLBCL) led by the FDA-approved CD19 targeting CARs Kymriah (tisagenlecleucel) and Yescarta (axicabtagene ciloleucel; refs. 2, 3). The gene discussed is CD19; the disease is acute lymphoblastic leukemia.