Phase 2 Trial Update of Ponatinib for Chronic Myeloid Leukemia and Philadelphia-positive Acute Lymphoblastic Leukemia

Ariad Pharmaceuticals announced updated clinical data from the pivotal PACE trial of ponatinib in patients with chronic myeloid leukemia (CML) or Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL) who are resistant or intolerant to Sprycel (dasatinib; Bristol-Myers Squibb) or Tasigna (nilotinib; Novartis) or who have the T315I mutation. These data show that 54% of chronic-phase CML patients in the trial, including 70% of patients who have a T315I mutation, achieved a major cytogenetic response.

Efficacy data were reported on 444 treated patients in six pre-specified cohorts receiving 45mg of ponatinib administered orally once daily. Patients were assigned to a cohort based on their phase of disease (chronic-phase, accelerated-phase or blast-phase CML/Ph+ALL) and T315I mutation status (with or without the mutation). Based on assessment of all evaluable chronic-phase patients in the trial, 54% achieved a major cytogenetic response (MCyR), with 44% achieving a complete cytogenetic response (CCyR). The median follow up of the chronic-phase CML patients was 10.1 months. MCyR was the primary end-point for chronic-phase CML patients. Of the 64 evaluable chronic-phase CML patients with the T315I mutation, 70% of these patients achieved a MCyR, with 66% achieving a CCyR. The MCyR rate in evaluable chronic-phase patients without the T315I mutation was 49%.

There were a total of 19 chronic-phase patients treated with ponatinib in the PACE trial who had previously received only one tyrosine kinase inhibitor (TKI). Thirteen of these patients had previously been treated with Gleevec (imatinib; Novartis) only and six had previously received either dasatinib or nilotinib. Of the 19 patients who received ponatinib following treatment with only one prior TKI, 84% achieved a MCyR.

Major hematologic response (MaHR) was the primary end-point in accelerated and blast-phase CML or Ph+ALL patients in the trial. Sixty percent of accelerated-phase patients in the resistant or intolerant cohort achieved a MaHR. Fifty percent of accelerated-phase patients with the T315I mutation achieved a MaHR. Thirty five percent of blast-phase CML or Ph+ALL patients in the resistant or intolerant group achieved a MaHR. Similarly, 33% of blast-phase CML or Ph+ALL patients with the T315I mutation also had a MaHR.

Thirty four percent of accelerated phase patients and 27% of blast phase or Ph+ALL patients in the resistant or intolerant cohorts achieved a MCyR. Twenty percent of patients in accelerated phase and 23% of patients in blast phase or Ph+ALL in this same group achieved a CCyR.

Ponatinib is an oral multi-targeted kinase inhibitor being developed for the treatment of hematological cancers. 

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