Chimeric antigen receptor (CAR) T cell therapy has transformed hematological cancer treatment, with six therapies now approved by the FDA. Four of these therapies (tisa-cel, axi-cel, brexu-cel, and liso-cel) target CD19 using single chain variable fragments (scFvs) derived from the heavy and light chain variable (VH and VL) regions of the monoclonal antibody FMC63.