Inclusion Criteria:

- Provide signed, written informed consent

- Have untreated AML according to World Health Organization (WHO) classification

- Male or post-menopausal female ≥ 65 years of age

- Unsuitable for intensive chemotherapy

- Be able to comply with study procedures and follow-up examination

- Male patient who are fertile agree to use and effective barrier method of birth
control to avoid pregnancies

- Have adequate liver and renal function as indicated by certain laboratory values

Exclusion Criteria:

- Received previous treatment with clofarabine

- Are receiving other chemotherapy or corticosteroids (low-dose corticosteroid for
pre-medication purposes are allowed)

- Have received prior treatment for leukemia. Growth factor, cytokine support,
leukopheresis or hydroxyurea will be allowed but must be discontinued at least 24
hours prior to start of treatment with clofarabine

- Have a psychiatric disorder that would interfere with consent, study participation,
or follow-up

- Have an active, uncontrolled systemic infection

- Are currently participating in other investigational drug studies or having received
other investigational drugs within the previous 30 days

- Have symptomatic central nervous system (CNS) involvement

- Blast transformation of chronic myeloid leukemia or acute promyelocytic leukemia