In a phase 1 study of a CAR T-cell targeting CD19 and containing a CD28 costimulatory domain, Lee et al. showed that children and young adults with heavily pretreated B-lineage ALL receiving this agent achieved a 70% CR, with 12/20 (60%) of patients attaining an MRD-negative CR (47). This evidence concerns the gene CD19 and acute lymphoblastic leukemia.