hi Dennis,
as you can see from the replies to your post, this is a contentious issue and how patients experience side effects, as far as i can see, is the main reason for doctors to consider a reduction in dose.
Nancy has provided a link to a study in France ... if you follow that link you will see that the patients that did not replapse after discontinuation with Glivec were those that had previously been treated with Interferon.... here is a snip from the article:
"The BCR-ABL tyrosine kinase inhibitor imatinib mesylate (Gleevec) induces complete cytogenetic responses (CCRs) in more than 85% of patients with chronic myelogenous leukemia (CML). However, patients in CCR relapse after imatinib interruption in the case of detectable residual disease.1 In fact, fewer than 10% of patients achieve a molecular remission, defined by an undetectable residual disease using real-time quantitative–polymerase chain reaction (RTQ-PCR).2 We previously reported the outcome of patients with CML in CCR after cessation of interferon-alpha during the pre-imatinib era. Seven (all with a negative PCR) of 15 patients did not relapse.3 Here, we discontinued imatinib in patients with CML with undetectable residual disease for longer than 2 years, under strict monitoring of the reappearance of BCR-ABL transcript, using monthly RTQ-PCR. Relapses (ie, positivity of RTQ-PCR) were observed early after imatinib discontinuation in 6 patients. Six patients previously exposed to interferon for more than 6 months are still in molecular remission with a median follow-up of 18 months (range, 9-24 months) after imatinib discontinuation."
i am aware of other studies where patients with very low residual disease have stopped Glivec and replaced it with low dose Interferon.
i know of one person who is on this study and who has had successfully maintained low pcr's, without intolerable side effects, over the last 18 months or so.
for myself, i would not consider a reduction in dose unless i had a plasma level test beforehand. but then i did not suffer from severe side effects when i was treated with Glivec (600mg) apart from peri-orbital oedaema, so it is easier for me to say that.
the issue surrounding the 'sub-optimal' (below 400mg) dose is that this may lead to resistance and once resistance is established you would be in more difficult territory and other therapies would have to be considered, but i am sure you are aware of these consequences.
If your side effects are intolerable then maybe you should discuss the possibilities of changing therapy to Dasatinib, or getting on to one of the ENACT trials as Pennie has done.
side effects can be difficult for some to cope with and they do differ in severity, which is why i believe there is a need for a plasma level test in some cases.
best wishes,
Sandy