FDA approves Pfizer’s Bosulif for Ph+ CML

The FDA on Tuesday approved Pfizer’s Bosulif (bosutinib) for the treatment of adult patients with chronic, accelerated, or blast phase Philadelphia chromosome-positive (Ph+) chronic myelogenous leukemia (CML) who are resistant to or who cannot tolerate other therapies, including Novartis' Gleevec (imatinib). "With the approval of tyrosine kinase inhibitors, we are seeing improvements in the treatment of CML based on a better understanding of the molecular basis of the disease," remarked Richard Pazdur, director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research.

The approval of the once-daily Abl and Src kinase inhibitor was based on data from Study 200, which included 546 patients with chronic, accelerated or blast phase Ph+ CML. All patients had disease that progressed after treatment with Gleevec or Gleevec followed by Bristol-Myers Squibb’s Sprycel (dasatinib) and/or Novartis’ Tasigna (nilotinib) and all patients were given Bosulif. At 24 weeks, data showed that 33.8 percent of patients treated with Gleevec only achieved a major cytogenetic response (MCyR). Of the patients who achieved MCyR at any time, 52.8 percent had their response last at least 18 months. Among patients previously treated with Gleevec followed by Sprycel and/or Tasigna, 26.9 percent achieved MCyR within the first 24 weeks of treatment and of these patients, 51.4 percent had their MCyR last at least nine months.

In patients with accelerated CML previously treated with at least Gleevec, 33 percent had a complete hematologic response and 55 percent had an overall hematologic response within the first 48 weeks of treatment. Meanwhile, 15 percent and 28 percent of patients with blast phase CML achieved complete hematologic response and overall hematologic response, respectively.

European regulators accepted a filing for the therapy in newly diagnosed Ph+ CML in the chronic phase in August 2011.

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