Tyrosine kinase inhibitors (TKIs) have been the standard of care for chronic myelogenous leukemia for over a decade, and a number of studies have collected data on their use. While the results show many common findings, there are some interesting differences in from one country to another.
In the U.S., the most commonly used TKI was Gleevec (82%) during the period 2007-2011, followed by Tasigna and Sprycel (both at 9%) (Henk and colleagues. Clin Ther 2015;37:124-133). About 20% of people were taking a second-generation TKI (Tasigna or Sprycel), in most cases after having been on Gleevec beforehand. Over time, 43% ultimately ended up taking one of the second-generation medications. During the five year period, people took an average of 90% of the doses prescribed.
Gleevec was also the most popular TKI in Canada, Australia and South Korea (Whiteley and colleagues. Curr Med Res Opin 2015;31:299-314). People typically started treatment about four months after being diagnosed with CML. About 30% of people switched to Sprycel or Tasigna because they couldn’t tolerate Gleevec or didn’t respond well enough. The proportion of people who achieved a major molecular response (MMR, i.e. a three-log reduction) or better within the first six months of treatment was substantially higher in Australia (54%) compared to South Korea (38%) or Canada (22%). However, at 18 months, about 60% of people overall had achieved MMR or better with treatment.
Treatment response was also examined in an analysis of medical records in the U.K., U.S., Germany and Japan (Trask and colleagues. Int J Hematol 2012;95:535-544). Among those starting with Gleevec, 53% achieved a complete cytogenetic response (CCyR) at one year, and 58% achieved MMR or better within 18 months.