In a Phase II single-cohort, multi-center global trial, the investigational Cluster of Differentiation 19 (CD19)-directed CAR T-cell therapeutic CTL019 (Tisagenlecleucel, Kymriah®, Novartis) demonstrated high response rates with an overall remission rate of 81% within 3 months and overall survival of 76% at 12 months in pediatric and young adult patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) (13). This evidence concerns the gene CD19 and precursor B-cell acute lymphoblastic leukemia.