Hi Bill,
My comment to Basil about the dose reduction was only in the context of him having acheived a molecular response. What the CML doctors in Italy were saying was that to reduce doses for this reasons... i.e maybe as a cost saving or to reduce side effects ... is not recommended if the patient is to continue with low molecular levels.
To get to a 3 or 4 log reduction with any of the TKI's like Glivec/Sprycel or Tasigna is the goal. To stay there over the long term is the challenge!
As I have commented to Elaine in anther post on this page, the most effective way to sustain low levels of molecular remission is to maintain the dose that got you there.... side effects permitting.
For some of us (using Glivec as the example) this dose may be 400mg, 600mg or 800mg.
In any one individual there are factors that can effect the plasma levels of the active drug.
These may be issues with drug adherence i.e taking the right dose consistantly and not missing doses on a regular basis.... or drug to drug interactions which affect bio-availability, as does food and drink interactions such as grapefruit juice etc.... or the individual pharmocokinetic profile of a patient.
So if a patient has already found the level of the drug which will get them, over time, from cytogenetic remission to molecular remission (3 or 4 log reduction from the level at diagnosis) ... and note that this may take up to and over 12 months... then they should keep with that dose as long as it maintains that level of molecular remission.
If a patient shows signs of losing their response on the molecular level then the doctor concerned should consider why this may be happening. It is not always caused by a mutation or further chromosomal abnormalities.
It may be that as time goes on people begin to regularly miss a few doses, or may just forget to take the drug (again not just one dose here and there but on a regular basis).
Adherence to long term therapy is quite challenging for patients, especially if there are side effects.
Drug holidays, if taken on a regular basis, are inevitably going to effect our responses to these drugs because the way they work is to do with maintaining a consistant plasma level (at or above 1000 ng/ml)of the drug.
Over the next few weeks... and when I have more time.... I will be writing a synopsis of the presentation I took part in during the EBMT meeting last weekend in Florence.
'Targeted therapy in CML:improving adherence, improving outcomes'
I hope to get permission from the doctors concerned to reproduce some of their slides on this site.
Meanwhile please do not worry about losing your response during this period of dose reduction. You really need to find the right dose that is effective and tolerable for you as an individual and this does take some time.
best wishes,
Sandy