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FDA Approves Bosulif (Bosutinib) for Chronic, Treatment-Resistant CML
The FDA announced on September 4 that it has approved Bosulif (bosutinib) for the treatment of chronic myelogenous leukemia (CML), a blood and bone marrow disease that usually affects older adults.
An estimated 5,430 men and women will be diagnosed with CML in 2012. Most people with CML have a genetic mutation, called the Philadelphia chromosome, which causes the bone marrow to produce tyrosine kinase. This enzyme triggers the development of too many abnormal and unhealthy granulocytes, a type of white blood cell. Granulocytes fight infection.
Bosulif is intended for patients with chronic, accelerated or blast-phase Philadelphia chromosome-positive CML who are resistant to or who cannot tolerate other therapies, including imatinib. Bosulif works by blocking the signal of the tyrosine kinase that promotes the development of abnormal and unhealthy granulocytes.
Other drugs recently approved by the FDA to treat various forms of CML include imatinib (2001), dasatinib (2006), and nilotinib (2007).
The safety and effectiveness of Bosulif were evaluated in a single clinical trial that enrolled 546 adult patients with chronic, accelerated or blast-phase CML. All of the patients had disease that progressed after treatment with imatinib or with imatinib followed by dasatinib and/or nilotinib, or who could not tolerate the side effects of prior therapy. All of the patients in the trial were treated with Bosulif.
In patients with chronic-phase CML, efficacy was determined by the number of patients who experienced a major cytogenetic response (MCyR) within the first 24 weeks of treatment. Results showed that 34% of patients who had been previously treated with imatinib achieved MCyR after 24 weeks. Of the patients who achieved MCyR at any time, 52.8% had a response that lasted at least 18 months. Among patients previously treated with imatinib followed by dasatinib and/or nilotinib, about 27% achieved MCyR within the first 24 weeks of treatment. Of those who achieved MCyR at any time, 51.4% had an MCyR that lasted at least 9 months.
In patients with accelerated CML previously treated with imatinib, 33% had blood counts that returned to the normal range (a complete hematologic response) and 55% achieved normal blood counts with no evidence of leukemia (an overall hematologic response) within the first 48 weeks of treatment. In addition, 15% and 28% of patients with blast-phase CML achieved a complete hematologic response and an overall hematologic response, respectively.
The most common side effects observed in patients receiving Bosulif were diarrhea, nausea, thrombocytopenia, vomiting, abdominal pain, rash, anemia, fever, and fatigue.
Bosulif is marketed by Pfizer.
For more information, visit the FDA Web site.