Bosutinib continues to demonstrate durable long-term efficacy and manageable toxicity in patients with chronic myeloid leukemia (CML) in chronic phase who are resistant or intolerant to imatinib, a new study published in the British Journal of Haematology has shown.1
Bosutinib is a dual SCR/ABL1 tyrosine kinase inhibitor approved by the U.S. Food and Drug Administration for the treatment of adult patients with chronic, accelerated, or blast phase Philadelphia chromosome (Ph)-positive CML with resistance or intolerance to prior therapy.
Researchers sought to evaluate patients factors that may impact long-term efficacy and safety of bosutinib 500 mg/day in adults with chronic phase CML resistant or intolerant to imatinib.
Results showed that after a median treatment duration of 24.8 months and a median follow-up of 43.6 months, the cumulative major cytogenetic response rate was 59%. The probability of maintaining cumulative major cytogenetic response at 4 years was 75% and 2-year overall survival was 91%.
Researchers found that prior imatinib cytogenetic response, baseline cumulative major cytogenetic response, prior interferon therapy and less than 6 months duration from diagnosis to imatinib treatment initiation, and no interferon treatment before imatinib were the most significant baseline predictors of both cumulative major cytogenetic response and complete cytogenetic response at 3 and 6 months.
In regard to safety, 86% of patients experienced diarrhea. Grade 3 to 4 diarrhea was significantly predicted by baseline bosutinib-sensitive BCR-ABL1 mutation.
“The baseline factors predictive of long-term patient outcomes identified here may allow identification of patient subgroups with Ph+ CML who might benefit optimally from bosutinib treatment. Overall, these findings highlight the therapeutic potential of bosutinib as second-line therapy in imatinib-resistant or –intolerant patients with CML in chronic phase,” the authors conclude.
1. Brümmendorf TM, Cortes JE, Khoury HJ, et al. Factors influencing long-term efficacy and tolerability of bosutinib in chronic phase chronic myeloid leukemia resistant or intolerant to imatinib [published online ahead of print November 4, 2015]. Brit J Haematol. doi: 10.1111/bjh.13801.