In one of the larger studies from Memorial Sloan Kettering Cancer Center, details of severity, duration and associated factors were studied for 83 patients including those who received FDA‐approved (axicabtagene ciloleucel and tisagenlecleucel) and institutionally developed products (19‐28z CD19 CAR T‐cell for relapsed/refractory ALL and BCMA directed for relapsed/refractory multiple myeloma) [26]. This evidence concerns the gene CD19 and acute lymphoblastic leukemia.