Much of what we know about the long-term outcomes of people with chronic myelogenous leukemia comes from clinical studies. Such studies provide important information about how well a person with CML can do over the longer term. But one of their limitations is that studies are selective in who is admitted, so the outcomes may not reflect what goes on in the real world of people with other illnesses, missed appointments, and doctors who may make different decisions.
So there is a need for studies looking at real-world circumstances. One such study in the Netherlands examined the registry of over 400 people with CML to see how they fared (Geelen and colleagues. Haematologica 2017; epublished August 31, 2017). The registry included people treated from 2008 to 2013.
Overall, 75% of people started treatment with Gleevec. However, almost one-half (44%) changed treatments within the first three years – mostly because of side effects or because the drug wasn’t effective enough.
In the first 18 months of treatment, 73% had achieved a complete cytogenetic response (CCyR, roughly corresponding to a 2-log reduction), and 63% had achieved a major molecular response (MMR; a 3-log reduction). At two years, most had achieved a deep molecular response: 69% had a 4-log reduction, and 56% had a 4.5-log reduction.
People who switched to a second-generation medication (Tasigna, Sprycel or Bosulif) reached these response milestones much earlier than those who took Gleevec. But many people on Gleevec eventually did reach these milestones.
A deep molecular response is important for two reasons. It shows that the person is responding very well to the treatment – CML is virtually undetectable in the person’s body. And a deep molecular response one of the criteria for entering a Stop trial, which enables people to go without medication (and be potentially drug-free for the foreseeable future).
The study also found that over the 6 year treatment period, about 1 in 3 people had a good enough response to make them eligible to enter a Stop trial. It’s likely that a higher proportion would have been eligible if they’d started treatment with a second-generation drug. However, these results show that entering a Stop trial – for those people interested in this option – is an achievable goal for many people with CML.