TCRαβ/CD19 Depletion of Stem Cell Grafts for Transplant

Inclusion Criteria: * Written informed consent (and written assent, if applicable) obtained prior to enrollment. * Age \< 21. * Lansky Play-Performance Scale or Karnofsky Index score ≥ 60%. * Adequate organ function (within 4 weeks of initiation of preparative regimen) as evaluated per institutional guidelines. Adequate major organ system function as demonstrated by: * Renal: Creatinine clearance or GFR of ≥ 60mL/min/1.73m2. * Hepatic: total bilirubin \< 2 mg/dL (unless due to Gilbert syndrome) and ALT/AST ≤ 2.5 times the upper limit of normal. * Cardiac: LVEF at rest ≥ 50% or SF ≥ 27% (by MUGA or ECHO). * Pulmonary: DLCO, FEV1, and FVC ≥ 50% of predicted corrected for hemoglobin. For patients \< 7 years of age or those unable to perform PFTs: O2 Sat ˃ 92% on room air by pulse oximetry and on no supplemental O2 at rest. * Available donor (matched/mismatched unrelated, mismatched related, related haploidentical) who is healthy and willing to donate peripheral blood stem cells. * Patients that have been diagnosed with graft rejection/failure or relapse may be eligible to receive a second transplant pending patient status. Exclusion Criteria: * Patients with HIV or uncontrolled fungal, bacterial, or viral infections. * Patients with active CNS leukemia or any other active site of extramedullary disease at the time of enrollment. * Recipient with HLA antibody against donor. * Patients that are pregnant, breastfeeding or unwilling to practice birth control during parti…