CD19 and acute lymphoblastic leukemia: The addition of PD-1 blockade to CD19 CAR-T therapy in 14 children (13 with pembrolizumab and 1 with nivolumab) with heavily pre-treated B-ALL including allo-SCT who initially had poor response to CD19 CAR-T therapy had improved persistence of CAR-T cells, thus resulting in better outcomes in this small, single-center study at Children’s Hospital of Pennsylvania (CHOP).