Chimeric antigen receptor (CAR) T cell therapy targeting the CD19 antigen on B-cell acute lymphoblastic leukemia (B-ALL) has transitioned from a highly investigational therapy with limited access to a commercial therapy with established toxicities, response and survival rates, and access in numerous countries. With over a decade of clinical study and 5 years of commercial access, data showing associations with success and failure have emerged. To address CAR T cell functional limitations …