Cumulative data from the clinical trials of donor-derived CAR-T cells have shown that donor-derived CAR-T cells targeting CD19 could effectively salvage relapsed B-ALL after allogeneic hematopoietic stem cell transplantation (HSCT) with a lesser risk of graft versus host disease (GVHD) flare [11–13]. Here, CD19 is linked to precursor B-cell acute lymphoblastic leukemia.