Evaluation of Efficacy and Safety of Ponatinib as Third-line Treatment in Patients with the Diagnosis of Chronic Phase Chronic Myeloid Leukemia

Philadelphia (Ph) is a fusion protein product of BCRABL and is a structurally active tyrosine kinase that causes chronic myeloid leukemia (CML) and a subgroup of acute lymphoblastic leukemia (ALL).1,2 Three tyrosine kinase inhibitors (TKI) (imatinib, dasatinib and nilotinib) targeting the BCR-ABL protein have been approved in the treatment of newly diagnosed chronic phase CML (CML-CP).3-5 Ponatinib is an orally applied, third generation strong BCR-ABL inhibitor that demonstrates activity against natural and mutational BCR-ABL proteins. Ponatinib includes a new triple bond connection that prevents the steric barrier that is caused by the remnant of the large isoleucine at 315th position in the T315I mutation.6 Ponatinib has been developed in order to overcome the limitations of TKI that are used in the current management of CML. We hereby retrospectively evaluated 6 patients (4 women and 2 men) with the diagnosis of CML and who had loss of response during second-line TKI treatments and who were treated with ponatinib as a third-line treatment.