The purpose of this study is to determine whether Clofarabine in combination with Busulfan is effective as a preparative transplant regimen for the treatment of leukemia and myelodysplastic syndromes

The success of allogeneic hematopoietic transplantation in the treatment of myeloid malignancies is determined by two main factors: the limiting of regimen-related toxicity and the prevention of recurrent leukemia. Over the past 10 years, considerable clinical research has been devoted to the reduction of regimen-related toxicity through the use of reduced-intensity (nonmyeloablative) transplants. However, leukemic relapse has remained a difficult obstacle. Thus, the need for highly effective, yet non-toxic regimens persists, particularly for elderly patients for whom very little overall progress has been made. Clofarabine is a chemotherapeutic agent with novel myelotoxic properties and proven low toxicity in older patients. These qualities suggest clofarabine may be a useful component of conditioning regimens for stem cell transplantation.

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