Bosutinib is a protein kinase inhibitor which inhibits the abnormal Bcr-Abl kinase that promotes CML.1
Bosutinib was evaluated in a phase I/II open-label study involving 570 patients with chronic, accelerated or blast phase, imatinib-resistant or imatinib-intolerant CML that had been previously treated with at least one tyrosine kinase inhibitor.1
Marketing approval was granted primarily on the basis of findings in 52 patients deemed as having an unmet medical need because other tyrosine kinase inhibitors were not appropriate due to resistance or the risk of adverse effects. Of these, 36 had chronic phase CML and 16 had either accelerated or blast phase CML.1
In patients with chronic phase CML treated previously with imatinib only, 59% (95% CI 52.9-65.0) achieved a major cytogenetic response (MCyR) at week 24 (primary efficacy endpoint). This compared with 40.9% (95% CI 31.6-50.7) of those treated previously with imatinib and dasatinib or nilotinib.1
In patients with accelerated or blast phase CML treated previously with at least imatinib, the proportions achieving MCyR at week 24 were 34.8% (95% CI 23.7-47.2) and 29.6% (95% CI 18.0-43.6), respectively.1
The most commonly reported adverse effects were GI upset, thrombocytopenia, rash, anaemia, pyrexia and raised serum ALT. 1
Bosulif has been given conditional marketing approval pending further evidence of clinical benefit and safety.
Further information: Pfizer