Prof Carlo Gambacorti-Passerini talks about his research into bosutinib as a treatment for patients with Philadelphia chromosome–positive chronic phase chronic myeloid leukaemia. The trial compared bosutinib with imatinib, the current standard therapy for newly diagnosed patients, and patients in the bosutinib group were shown to respond almost twice as quickly as those treated with imatinib. Bosutinib produced similar levels of patient response as other tyrosine kinase inhibitors such as nilotinib and dasatinib but is associated with a lower toxicity profile. Prof Gambacorti-Passerini discusses this difference, talks about the benefits in terms of patient tolerance, safety levels and disease progression but also explains the adverse events encountered by the patients entered into this trial.