Stem Cell Transplant for Juvenile Myelomonocytic Leukemia (JMML)

Prior to transplantation, subjects will receive BUSULFAN via the central venous line, six
times a day for four days, CYCLOPHOSPHAMIDE via the central venous line once a day for two
days, and MELPHALAN via the central venous line for one day. Busulfan, cyclophosphamide, and
melphalan are given to destroy the subject's leukemia. As well, these drugs will destroy the
subject's own immune system to help ensure the new bone marrow takes and grows after
transplantation.

On the day of transplantation, bone marrow or umbilical cord blood from the donor will arrive
to the bone marrow transplant unit and be transfused via venous line. These new cells will
replace the subject's bone marrow.

Inclusion Criteria:

- Patients must have a diagnosis of JMML and fulfill these minimal criteria
(International diagnostic criteria for JMML):

- Leukocytosis (> 13,000) with absolute monocytosis (> 1,000)

- The presence of immature myeloid cells in the peripheral blood

- Less than 30% marrow blasts

- Absence of t(9:22) or BCR-ABL transcript

- Adequate major organ function including:

- Cardiac: ejection fraction > 45%

- Hepatic: no clinical evidence of hepatic failure (e.g. coagulopathy,
ascites)

- Karnofsky performance status > 70% or Lansky score > 50%

- Creatinine must be < 2 x normal for age

- Written informed consent.

Exclusion Criteria:

- Active uncontrolled infection within one week of HCT.