Highlights from the American Society of Hematology (ASH) annual meeting, San Diego CA, December 3-6, 2016 – A new Canadian study has examined how often people with CML are tested to determine their response to medication (Hillis and colleagues. ASH 2016; abstract 3079). Information was obtained from patient registries for over 600 people treated with Gleevec in the Canadian provinces of Ontario, Quebec, British Columbia and Saskatchewan for the period 2001-2015. The authors found that there was room for improvement in how often physicians obtain blood tests, and how they make decisions about treatment based on the test results.
The current recommendation is that people should be tested at 3, 6 and 12 months after starting a medication (Baccarani and colleagues. Blood 2013;122:872-884). The goal is to achieve certain “milestones” that indicate a good response to treatment: a 1-log reduction at 3 months, a 2-log reduction at 6 months, and a 3-log reduction at 12 months. (“Log” means that the number of leukemia cells has been reduced by a factor of 10 against a lab standard, so that 1-log means from 100% to 10%, 2-log from 100% to 1%, and so on.)
Overall, about 70-80% of doctors adhered to the 12-month test, but the results were not uniform in the different provinces. In Ontario, only 66% of doctors ordered a test at 3 months, but this proportion increased to 80% at months 6 and 12, and to 84% at month 18. The reverse was seen in B.C.: the rate of testing was high at 3 months (95%), then steadily declined to 86% at month 6, 73% at month 12, and 65% at month 18. However, it should be noted that part of the discrepancy was due to different guidelines used across Canada during this time period. In B.C. and Saskatchewan, doctors were told to follow guidelines produced by European LeukemiaNet, whereas Quebec developed its own guidelines, and Ontario doctors were given no guidelines to follow.
Treatment decisions also differed across provinces. People in B.C. were less likely to continue taking Gleevec (39%), compared to people in Quebec (55%) and Saskatchewan (67%). A similar proportion of people in B.C. and Quebec (36-39%) were switched to a second-generation medication (Tasigna or Sprycel). People in B.C. were three-fold more likely to undergo a bone-marrow transplant compared to people in Quebec (11% vs 4%). More troubling was that in the period 2009-2014, about 1 in 4 people in Saskatchewan who didn’t respond to Gleevec were kept on the medication and were not switched to a more effective therapy such as Tasigna or Sprycel.