Clofarabine and Cytarabine in Treating Older Patients With AML or High-Risk MDS

Inclusion Criteria:

Diagnosis of 1st relapse or refractory AML; or patients with high risk MDS (10-19% blasts) who have received previous therapy 1st remission must have been < 1 year
Must not have received previous ara-C (cytarabine) or clofarabine
Eastern Cooperative Oncology Group (ECOG) Performance Status of 0-2
Not candidates for standard 7 + 3 regimen (Ara-C and an anthracycline), high dose Ara-C, or hematopoietic stem-cell transplantation
Serum creatinine =< 1.0 mg/dL; if serum creatinine > 1.0 mg/dL, then the estimated glomerular filtration rate (GFR) must be > 50 L/min/1.73 m^2 as calculated by the Modification of Diet in Renal Disease equation
Serum bilirubin =< 1.5 x upper limit of normal (ULN)
Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) =< 2.5 x ULN
Alkaline phosphatase =< 2.5 x ULN
Capable of understanding the investigational nature, potential risks and benefits of the study, and able to provide valid informed consent
Female patients of childbearing potential must have a negative serum pregnancy test within 2 weeks prior to enrollment
Male and female patients should use an effective contraceptive method during the study and for a minimum of 6 months after study treatment

Exclusion Criteria:

Current concomitant chemotherapy, radiation therapy, or immunotherapy other than as specified in the protocol
Patients with acute promyelocytic leukemia (APL)
Use of investigational agents within 30 days or any anticancer therapy within 2 weeks before study entry with the exception of hydroxyurea; the patient must have recovered from all acute toxicities from any previous therapy
Have 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 treatment
Patients with a 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)
Pregnant or lactating patients
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

Have had a diagnosis of another malignancy, unless the patient has been disease free for at least 3 years following the completion of curative intent therapy including the following:

Patients with treated non-melanoma skin cancer, in situ carcinoma, or cervical intraepithelial neoplasia, regardless of the disease-free duration, are eligible for this study if definitive treatment for the condition has been completed.
Patients with organ-confined prostate cancer with no evidence of recurrent or progressive disease based on prostate-specific antigen (PSA) values are also eligible for this study if hormonal therapy has been initiated, or a radical prostatectomy or definitive radiotherapy has been performed
Have currently active gastrointestinal disease, or prior surgery that may affect the ability of the patient to absorb oral clofarabine