|Exclusion Criteria:||1) Diagnosis of acute promyelocytic leukemia (APL), (French-American-British classification M3 or WHO classification of APL with t(15;17)(q22;q12), (PML/RAR alpha fusion gene and variants).|
2) Prior treatment with clofarabine.
3) Prior treatment for AML or an AHD (excluding supportive care, hydroxyurea, hematopoietic cytokines, or lenalidomide [the latter specifically for an AHD only]). Hematopoietic cytokines and lenalidomide must not have been received within 14 days prior to first dose of study drug; hydroxyurea is allowed on study to control WBC counts. If any of the above treatments have been received for AML or an AHD within the permissible time periods, drug-related toxicities must have recovered to Grade 1 or less prior to first dose of study drug.
4) Prior hematopoietic stem cell transplant (HSCT).
5) Prior external beam radiation therapy to the pelvis.
6) Investigational agent received within 30 days prior to the first dose of study drug. If received any investigational agent prior to this time point, drug-related toxicities must have recovered to Grade 1 or less prior to first dose of study drug.
7) Systemic fungal, bacterial, viral, or other infection not controlled (defined as exhibiting ongoing signs/symptoms related to the infection and without improvement, despite appropriate antibiotics or other treatment).
8) Any other severe concurrent disease, or have a history of serious organ dysfunction or disease involving the heart, kidney, liver or other organ system that may place the patient at undue risk to undergo therapy with clofarabine.
9) Clinical evidence suggestive of central nervous system (CNS) involvement with leukemia unless a lumbar puncture confirms the absence of leukemic blasts in the cerebrospinal fluid (CSF)
10) Prior positive test for the human immunodeficiency virus (HIV).
11) WBC >50 × 10^9/L; the first 3 patients enrolled on the study will be required to have a WBC of <20 × 10^9/L.
12) Have psychiatric disorders that would interfere with consent, study participation, or follow-up.
13) Have been diagnosed with another malignancy, unless the patient has been disease free for at least 5 years following curative intent therapy, following exceptions: Patients with treated nonmelanoma skin cancer, in situ carcinoma, or cervical intraepithelial neoplasia, regardless of disease-free duration, if definitive treatment for the condition has been completed or patients with organ-confined prostate cancer with no evidence of recurrent or progressive disease based on prostate-specific antigen (PSA) values if hormonal therapy has been initiated or radical prostatectomy has been performed.
14) Are pregnant or lactating.