TCRαβ-depleted Progenitor Cell Graft With Early Memory T-cell DLI, Plus Selected Use of Blinatumomab, in naïve T-cell Depleted Haploidentical Donor Hematopoietic Cell Transplantation for Hematologic Malignancies

This is a phase I, prospective clinical trial studying the safety and feasibility of providing early memory T-cell DLI. The primary objective is: \- To assess the safety and feasibility of early CD45RA-depleted DLI administration. The secondary objectives are * To assess the safety and feasibility of the addition of blinatumomab in the early post-transplant period in patients with CD19+ malignancy. * To measure and describe the pharmacokinetics of rabbit ATG in HCT recipients on this study.

The purpose of the study is to learn more about the effects (good and bad) of transplanting progenitor (blood making) cells and donor lymphocytes (white blood cells) donated by a partially matched family member that have been modified in a laboratory, to children and young adults with a high risk cancer that is in remission but is at high risk of relapse. This study builds upon what we have learned from recently completed studies and will be testing the safety and effects of the chemotherapy and the combination of two different types of blood cell infusions on the transplant recipient's disease and overall survival. In this study, participants with high-risk hematologic malignancies who lack an available suitable human leukocyte antigen (HLA) matched related/sibling donor (MSD) or matched unrelated donor (MUD), will undergo allogeneic hematopoietic cell transplantation (HCT) consisting of a TCRαβ-depleted haploidentical donor product with additional memory cell donor lymphocyte infusion (DLI) given in the early postHCT time period. Prior to the infusion of donor cells, a preparative regimen consisting of antibodies and chemotherapy will be given. The preparative regimen includes the following total dosages: ATG 5mg/kg (over days -12 to -10); Cyclophosphamide 60 mg/kg (day -9); Fludarabine 150 mg/m2 (over days -8 to -4); Thiotepa 10 mg/kg (divided in two doses on day -3); Melphalan 70 mg/m2 (over days -2 to -1). Following this regimen the TCRαβ-depleted haploidentical donor product will be given on day 0 (subsequent infusion given on day +1 if needed to achieve goal CD34+ cell dose. Approximately 2 weeks later the memory cell donor lymphocyte infusion (DLI) will be given at a dose previously determined to be safe and effective. Blinatumomab will be empirically added for patients with CD19+ malignancy and given at least four weeks after the memory cell DLI.