8. In the absence of rapidly progressing disease, the interval from prior treatment to time of initiation of ponatinib administration will be at least 2 weeks for cytotoxic agents OR at least 5 half-lives for cytotoxic/non-cytotoxic agents. Use of one dose of cytarabine (up to 2 g/m2) or hydroxyurea for patients with rapidly proliferative disease is allowed before the start of study therapy and for the first eight weeks on study therapy from the day of enrollment, either prior to or concomitantly with ponatinib administration initially to control the peripheral blast count. Concurrent therapy for central nervous system (CNS) prophylaxis or continuation of therapy for controlled CNS disease is permitted. Controlled CNS leukemia is defined by the absence of active clinical signs of CNS disease and no evidence of CNS leukemia on the most recent 2 simultaneous cerebrospinal fluid (CSF) evaluations.