This study is sponsored by Genzyme Japan K.K. The purpose of this study is to assess the safety, tolerability and pharmacokinetics of Clofarabine (JC0707) intravenously administered to Japanese adult patients with newly diagnosed or relapsed/refractory Acute Myeloid Leukemia (AML) at 20, 30, and 40 mg/m2/day on a 5-day dose schedule.