Pfizer and Avillion have filed applications on both sides of the Atlantic seeking to expand the treatment scope of chronic myeloid leukaemia therapy Bosulif.

The companies are seeking approval for the drug’s use to treat patients with newly diagnosed chronic phase Philadelphia chromosome-positive (Ph+) CML.

In the US, Bosulif (bosutinib) is already approved to treat of adult patients with PH+ CML who are resistant or intolerant to prior therapy.

In the EU, the drug has a conditional marketing authorisation for the treatment of those previously treated with one or more tyrosine kinase inhibitors (TKIs) and for whom imatinib, nilotinib and dasatinib are not considered appropriate treatment options.

The submissions are based on results from BFORE, a multi-centre multinational, open-label Phase III study which showed that the drug was linked with a significantly higher rate of patients achieving major molecular response (the primary endpoint) at 12 months versus the rate achieved in patients treated with imatinib (Novartis' Gleevec).

Bosulif is an oral, once-daily, tyrosine kinase inhibitor which inhibits the Bcr-Abl kinase that promotes CML; it is also an inhibitor of Src-family kinases.