CD19 and acute lymphoblastic leukemia: We have previously shown that some LPC subpopulations (CD34+/CD19− in BCP‐ALL and CD34+/CD7− and CD34− in T‐ALL), that have self‐renewal capacity over several generations in NSG mice, are resistant to therapy.8,12,16 The results in this study add to the evidence of refractoriness in these subpopulations, which would also be resistant to chimaeric antigen receptor (CAR) T cells directed at CD19 or CD7.