Primary Outcome Measures:
- incidence of hematopoietic recovery and engraftment [ Time Frame: at day 42 after HCT ] [ Designated as safety issue: No ]
Secondary Outcome Measures:
- - Incidence of secondary graft failure [ Time Frame: at day 100 after HCT ] [ Designated as safety issue: No ]
- - Incidence of acute graft-versus-host disease (GVHD) [ Time Frame: at 100 days after HCT ] [ Designated as safety issue: No ]
- - Incidence of chronic GVHD [ Time Frame: at 1 year after HCT ] [ Designated as safety issue: No ]
- - Incidence of regimen-related toxicity (RRT) [ Time Frame: at 1 year after HCT ] [ Designated as safety issue: No ]
- - Immune reconstitution [ Time Frame: over the first two years after HCT ] [ Designated as safety issue: No ]
- Probability of survival [ Time Frame: at 1 and 2 years after HCT ] [ Designated as safety issue: No ]
Intervention Details:
Procedure: Hematopoietic Stem Cell Transplant
Certain cancers can be treated by giving patients stem cells that come from someone else. This is called a stem-cell transplant. As part of the transplant process, patients receive high doses of chemotherapy and/or radiation to treat their underlying disease, such as cancer. As one of its effects, this treatment also kills the healthy stem cells that are already in the marrow. The transplant provides new stem cells for the patient from a healthy donor; that replace the bone marrow and allow the blood counts to recover.
Procedure: Thymic Shielding
protecting the thymus during radiation
Procedure: Total Body Irradiation
Six days before the stem cells are given (day -6), subjects will receive total body irradiation with thymic shielding. Thymic shielding is done by placing a piece of lead on the chest during the irradiation treatment so that the irradiation beams do not go to the thymus.
Drug: Cyclophosphamide, Fludarabine
Day -5 through Day -2, subjects will receive a chemotherapy regimen of Fludarabine, Cyclophosphamide via central line
All subjects will be given the same treatment regimen of TBI, Fludarabine, Cyclophosphamide, and ATG, followed by an alternate donor stem cell transplant. Since this treatment regimen has been given before, without thymic shielding, we will compare the outcomes of these patients with the historical data from subjects who did not receive thymic shielding.