Immunoablative Mini Transplant (Hematopoietic Peripheral Blood Stem Cell Transplant [HPBSC])

• Evaluate the morbidity and mortality of matched related and unrelated hematopoietic progenitor cell (HPC) transplantation at Children's Memorial Hospital using high dose CD34+ rich HPCs after a reduced intensity conditioning regimen. [ Time Frame: To study end ] [ Designated as safety issue: Yes ]
  
• Determine the toxicity of a reduced intensity conditioning regimen consisting of Fludarabine and Busulfan. [ Time Frame: To study end ] [ Designated as safety issue: Yes ]
  

• Validate the pharmacokinetics of once-a-day dosing of intravenous Busulfan given as a 3-hour infusion, using a limited number of samples. [ Time Frame: To study end ] [ Designated as safety issue: No ]
  
• Assess chimeric engraftment utilizing this regimen in malignant and non-malignant disorders. [ Time Frame: To study end ] [ Designated as safety issue: No ]
  
• Assess the relapse rate of patients transplanted with this reduced intensity regimen. [ Time Frame: To study end ] [ Designated as safety issue: No ]
  
• Determine the incidence of acute and chronic Graft vs. Host Disease (GVHD) using prophylaxis with Cyclosporine A and mycophenolate mofetil following this reduced intensity regimen. [ Time Frame: To study end ] [ Designated as safety issue: No ]
  

Procedure: Immunoablative Hematopoietic PBSC Transplant
Immunoablative conditioning chemotherapy regimen, followed by transplantation of peripheral blood stem cells on Day 0 of the conditioning regimen.
Procedure: Busulfan pharmacokinetics
Pharmacokinetics of once-a-day dosing of intravenous busulfan as a 3-hour infusion
Radiation: CNS prophylaxis radiation
• Patients diagnosed with ALL over 1 year of age and without prior CNS disease will receive CNS prophylaxis radiation to the whole brain prior to transplant.
• Patients diagnosed with ALL with prior CNS disease over the age of 1 year will be treated with prophylaxis radiation to the whole brain and spine prior to transplant.

The standard treatment in many disorders of the bone marrow is high dose chemotherapy and whole-body radiation treatment followed by the stem cell transplant. This type of transplant not only suppresses or kills off the immune system, but is very toxic to the bone marrow. This study uses a chemotherapy regimen that will suppress the patient's immune system; however, it is non-myeloablative (not toxic to the bone marrow). It does not use whole-body radiation treatment. This approach can minimize the short- and long-term effects of transplantation. Other studies have shown that using chemotherapy followed by bone marrow transplantation without whole-body radiation can produce similar results as treatment with whole-body radiation.

Patients will be given chemotherapy with Fludarabine and Busulfan prior to the stem cell transplant. This treatment not only destroys diseased cells, but it also kills normal bone marrow cells. Following this experimental treatment, the patient will be given the stem cells through a central venous catheter (tube inserted in a vein). When the healthy stem cells are given to the patient, they will replace the destroyed bone marrow cells and produce new blood cells. The Allogeneic (not one's own) stem cells used in this experimental transplant will be obtained from a related matched donor or from an unrelated matched donor located through the National Marrow Donor Program.