Study of Stem Cell Transplant for Leukemia and Myelodysplastic Syndromes Using Clofarabine and Busulfan Regimen

Inclusion Criteria:

Disease Criteria:

* Acute myelogenous leukemia (AML)
* Acute lymphocytic leukemia (ALL)
* Myelodysplastic syndromes (MDS) Refractory anemia (RA) with adverse cytogenetics (SWOG criteria) or beyond (RAEB, RAEB-T, AML)
* Other Myeloproliferative Disorders Myelofibrosis, Agnogenic Myeloid Metaplasia, Chronic Myelomonocytic Leukemia (CMML)
* Chronic lymphocytic leukemia (CLL) High risk or advanced disease

Other Inclusion Criteria:

* 18 years of age or older
* Related or unrelated donor with HLA criteria as follows:

  * Related donors: a serologic equivalent HLA Class I (A, B, and C) and Class II DRB1 or DQB1 matched donor OR a donor who is a single 1 antigen mismatched for A, B, C, DRB1, or DQB1 loci
  * Unrelated donors: sequence-based typing fully matched A, B, C, DRB1, and DQB1 allele-matched donor OR a donor who is no greater than 1 antigen mismatched for A, B, C, DRB1, or DQB1 loci
* Able to provide valid informed consent.
* Female patients must have a negative serum pregnancy test within 2 weeks prior to enrollment.
* Male and female patients must use an effective contraceptive method during the study and for up to 12 months after study treatment.

Exclusion Criteria:

Organ Function Criteria:

* Cardiac: symptomatic coronary artery disease or ejection fraction \<45% or uncontrolled cardiac failure
* Pulmonary: FEV1 or DLCO (corrected) \<50% of predicted values and/or receiving continuous supplementary oxygen
* Hepatic: Bilirubin ≥ 1.2 mg/dL or AST/ALT ≥ 3x upper limit of normal (ULN) unless the liver is involved with malignant disease
* Renal: creatinine clearance \< 60 mL/min (24-hour urine collection) or \<50 mL/min (Glofil test)
* Karnofsky score \<60%
* Active CNS disease
* Prior hematopoietic transplantation (autologous or allogeneic) \<6 months prior to study entry
* Use of investigational agents less than or equal to 30 days before study entry.
* Life threatening, or clinically significant infection
* Any significant concurrent disease, illness, or psychiatric disorder that would compromise patient safety or compliance, interfere with consent, study participation, follow up, or interpretation of study results.
* Female patients who are pregnant or breast feeding
* HIV-positive