Trial Evaluating MGTA-456 in Patients With High-Risk Malignancy

25 mg/m2 IV over 1 hour (\<10 kg: 0.83 mg/kg IV over 1 hour)

60 mg/kg IV over 2 hours

165 cGy twice daily

Tacrolimus will start day -3 and will be administered as a continuous IV infusion at a starting dose of 0.03 mg/kg/day. Goal trough levels will be 10-15 ng/mL for the first 14 days post-transplant and then decreased to a goal of 5-10 ng/ml thereafter.

MMF 3 gram/day IV/PO for adult patients divided in 2 or 3 doses. Pediatric patients will receive MMF at the dose of 15 mg/kg/dose (max 1 gram per dose) every 8 hours beginning day -3.

5 ug/kg/d until the absolute neutrophil count (ANC) is \>2500/uL for 2 consecutive days

BU IV once daily with dose based on Pharmacokinetics (PK) calculator over 3 hours

50 mg/m2/day (1.7 mg/kg/day if \< 10 kg) IV over 30 min

The target cell dose is \>10 x 106 CD34/kg with a maximum TNC 2.7 x 108/kg for children (\<18 years) and 8.1 × 108 cells/kg \[expanded product only\] for adults based on the highest cell dose windows evaluated in prior studies.