Naïve T Cell Depletion

Sometimes the transplanted white blood cells from a donor attack the body's normal tissues (called graft versus host disease). Removing a particular type of T cell (naive T cells) from the donor cells before the transplant may stop this from happening.

Patients are randomized to 1 of 2 arms. All patients receive 1 of 3 conditioning regimens.

CONDITIONING REGIMEN A: Patients undergo total body irradiation (TBI) twice daily (BID) on days -10 to -7, then receive thiotepa intravenously (IV) over 3 hours once daily (QD) on days -6 and -5, and fludarabine IV over 30 minutes once daily on days -6 to -2.

CONDITIONING REGIMEN B: Patients undergo TBI BID on days -8 to -5, then receive fludarabine IV over 30 minutes QD on days -4 to -2, and cyclophosphamide IV over 1 hour QD on days -3 and -2.

CONDITIONING REGIMEN C: Patients receive fludarabine IV over 30 minutes QD on days -6 to -2, busulfan IV over 180 minutes QD on days -5 to -2, and undergo total body irradiation BID on day -1.

ARM I: Patients receive naive T-cell depleted PBSCs on day 0.

ARM II: Patients receive unmanipulated T cell-replete BM on day 0.

GVHD PROPHYLAXIS: All patients receive tacrolimus IV on days -1 to +50 followed by a taper in the absence of grade II-IV aGVHD. Patients also receive methotrexate IV on days +1, +3, +6, and +11.

Additionally, all patients undergo echocardiography (ECHO) and cerebrospinal fluid (CSF) collection at baseline as well as blood sample collection and bone marrow aspiration with or without biopsy throughout the trial.

After completion of study treatment, patients are followed up at days 28, 56, 90, 180, 270, and 365 and then at months 15, 18, 21, and 24.