The FDA has approved bosutinib (Bosulif) to treat chronic myelogenous leukemia (CML). The drug 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 (Gleevec).
The safety and effectiveness of Bosulif was evaluated in a single clinical trial that enrolled 546 adult patients with chronic, accelerated, or blast phase CML. All patients had disease that progressed after treatment with imatinib or imatinib followed by dasatinib (Sprycel) and/or nilotinib (Tasigna), or who could not tolerate the side effects of prior therapy.
Results showed 34% of patients with chronic phase CML who had been previously treated with imatinib achieved a major cytogenetic response after 24 weeks. Of the patients who achieved a major cytogenetic response at any time, 52.8% had their response last at least 18 months. Among patients previously treated with imatinib followed by dasatinib and/or nilotinib, about 27% achieved a major cytogenetic response within the first 24 weeks of treatment. Of those who achieved a major cytogenetic response at any time, 51.4% had their response last at least 9 months.
In patients with accelerated CML previously treated with at least imatinib, 33% had blood counts return to normal range (complete hematologic response) and 55% achieved normal blood counts with no evidence of leukemia (overall hematologic response) within the first 48 weeks of treatment. Meanwhile, 15% and 28% of patients with blast phase CML achieved complete hematologic response and overall hematologic response, respectively.
The most common side effects observed in those receiving bosutinib were diarrhea, nausea, thrombocytopenia, vomiting, abdominal pain, rash, anemia, fever, and fatigue. ■