Clofarabine and High-Dose Melphalan Followed by Donor Stem Cell Transplant in Patients With Acute Myeloid Leukemia, Acute Lymphocytic Leukemia, or Myelodysplastic Syndromes

DISEASE CHARACTERISTICS:

* Diagnosis of one of the following:

  * Acute myeloid leukemia
  * Acute lymphocytic leukemia
  * Myelodysplastic syndromes
* Disease meets 1 of the following criteria:

  * In first complete remission (CR)
  * In second CR
  * In relapse
* No more than 50% blasts in bone marrow
* Not deemed eligible for standard transplantation regimens by the attending physician, or at high risk for relapse
* No suspected or proven CNS leukemia
* HLA-matched (6/6) sibling donor available

PATIENT CHARACTERISTICS:

* Karnofsky performance status 50-100%
* Glomerular filtration rate (pediatric patients) or creatinine clearance ≥ 60 mL/min OR serum creatinine \< 1.5 times upper limit of normal (ULN)
* Serum bilirubin ≤ 2.0 mg/dL
* AST and ALT ≤ 2.5 times ULN
* LVEF ≥ 50% by ECHO or MUGA scan
* DLCO or FEV\_1 ≥ 40% predicted
* Not pregnant
* Negative pregnancy test
* No concurrent uncontrolled illness including, but not limited to, any of the following:

  * Ongoing, active, or poorly controlled infection
  * Symptomatic congestive heart failure
  * Unstable angina pectoris
  * Cardiac arrhythmia
  * Poorly controlled pulmonary disease
  * Psychiatric illness/social situation that would limit compliance with study requirement
* No active cytomegalovirus (CMV) or fungal disease
* HIV negative

PRIOR CONCURRENT THERAPY:

* Recovered from prior intensive chemotherapy (pediatric patients)
* At least 100 days since prior autologous stem cell transplantation
* At least 100 days since prior radiotherapy administered as part of a transplantation conditioning regimen
* At least 4 weeks since prior chemotherapy
* At least 24 hours since prior hydroxyurea for blast count control