AMD3100 for Sensitizing in Allogeneic Blood or Marrow Transplant for Chemotherapy Resistant Pediatric Acute Leukemia

This study is for patients 2-21 years old who have acute leukemia that has not responded well to chemotherapy and will have a bone marrow transplant. This is a pilot (phase 1) study of AMD3100(also called Plerixafor, Mozobil). AMD3100 is given in combination with a standard pre-transplant conditioning regimen (total body irradiation, etoposide and cyclophosphamide). The conditioning regimen is the treatment that is given just before the transplant. This treatment kills leukemia cells as well as healthy bone marrow and immune cells. Researchers want to learn more about how AMD3100 affects acute leukemia cells. Blood and bone marrow samples from study participants will be collected to find out if AMD3100 is making patients' cells more sensitive to the conditioning regimen and to find out how it does this.

The first six patients receive three daily doses (240 mcg/kg via IV). If it appears that three doses do not significantly increase the side effects of transplant conditioning, the investigators will give a second group of six patients five daily doses.

The first six patients will receive three daily doses of AMD3100 (240 mcg/kg via IV). If it appears that three doses do not significantly increase the side effects of transplant conditioning, the investigators will give a second group of six patients five daily doses.

AMD3100 is given in combination with a standard pre-transplant conditioning regimen (total body irradiation, etoposide and cyclophosphamide.) AMD3100 causes healthy bone marrow cells to be released from the bone marrow into the blood so that they can be collected in patients who will have peripheral (blood stream) blood stem cell transplants. AMD3100 also pushes out leukemia cells from the bone marrow. Research in animals and in test tubes shows that the bone marrow partially protects leukemia cells from chemotherapy and radiation. AMD3100 could make leukemia treatments better by pushing out the leukemia cells from the bone marrow and making them more sensitive to treatment. Clinical trials combining AMD3100 with normal doses of chemotherapy are being done for relapsed acute leukemia. Researchers hope AMD3100 can be given with conditioning regimen safely without causing more side effects. Up to 12 participants will be enrolled and estimated accrual duration is 2 years.

Eligibility Criteria:
Inclusion Criteria:

* Must have chemotherapy-resistant acute leukemia (primary refractory or relapsed and refractory AML, ALL, undifferentiated, bi-lineage or mixed lineage leukemia)
* Participant must have a well HLA matched related, mismatched related or unrelated marrow donor with whom the patient is allele matched at at least 7 of 8 HLA loci or a single unrelated cord blood unit matched at at least 4 of 6 HLA loci with minimal dose of 4x10(7)NC/Kg

Exclusion Criteria:

* Prior allogeneic or autologous hematopoietic stem cell transplantation
* Prior exposure to AMD3100
* Active central nervous system leukemia
* Uncontrolled viral, bacterial, fungal, protozoal infection
* HIV infection
* Does not meet standard organ function for transplant