Report from the American Society of Clinical Oncology (ASCO), Chicago IL, May 29-June 2, 2015 – Bosulif (bosutinib) is one of the more recent TKIs used for the treatment of CML. It’s a potent drug that is generally kept in reserve for people with an inadequate response or poor tolerability with another TKI, such as Gleevec, Tasigna or Sprycel.
According to new results of five years of treatment, people who respond well to Bosulif are likely to continue doing well (Lipton and colleagues. ASCO 2015; abstract 7076). The study is an ongoing phase I/II trial of people who started to take Bosulif after they didn’t respond to Gleevec. At the 5-year mark, 41% were still taking their medication. Overall, 60% had achieved a major cytogenetic response or complete cytogenetic response. People generally responded within the first two years, and very few lost their response thereafter. Over the 5-year period, only 4% of those remaining in the study progressed to accelerated-phase CML. Overall survival at five years in this group of initially treatment-resistant people was 84%.
The most common side effect in the first year of treatment was diarrhea, but very few people experienced diarrhea thereafter. The incidence of cardiac and vascular (mostly high blood pressure) side effects was about 12% in the first year, declining to about 7% at five years. Other side effects included cough, fever, and fluid around the lung (pleural effusion).
A separate study presented the long-term results of Bosulif in people with advanced CML (Gambacorti-Passerini and colleagues. ASCO 2015; abstract 7068). At four years, only 21% of people were still on treatment. The reasons for stopping were commonly disease progression or death. Among those who responded, a majority achieved a hematologic response and about 40% had a major cytogenetic response. Side effects were the same as those seen in other studies: diarrhea, hypertension, and pleural effusion. A majority of people experienced a serious side effect, most commonly pneumonia.