In a case series by Grupp et al., two children with relapsed and refractory pre-B cell ALL received 1.4 × 106–1.2 × 107/kg CD19 4-1BB CAR T cells and both patients showed a complete remission, one of which was ongoing 11 months post-treatment (current status unknown) [80]. This evidence concerns the gene CD19 and acute lymphoblastic leukemia.