Dear Richard,
You must be relieved that the cause of your recent problems has been identified...i.e lack of B12, which of course is not something that you would welcome under normal circumstances. However, in this case at least you can now take steps to increase your levels and I assume that you are receiving B12 injections on a regular basis? I hope so.
I wonder if this is something that may be a consequence of long term therapy? I know a few people on longer term therapy who suffer from a lack of B12, but having said that it might well be that there are many different causes and they would have developed low B112 levels anyway.
As for low and stable PCR results, yes your doctor is right of course, but I have just been to a meeting in Milan regarding how long term deep molecular responses indicate not only that you have a good response to therapy, but also that you may be in the select few that can stop therapy and live in treatment free remission.
TFR will not be achievable for the majority, but studies are showing that for the lucky few who reach MR3 (0.1% BCR-ABL) very quickly, at least within 3-6 months, and go on to achieve deeper stable MRs (preferably more than 3 years) down towards MR4.5 MR5 etc. are the people who have the best chance of stopping and living in TFR for the long term.
The thinking is that although a small number of people do achieve fast and deep MRs on imatinib in first line, there is an increase in the number of people on 2nd gen TKIs in first line who reach deeper MRs at a faster rate. 2Gen TKIs undoubtedly have a more profound effect on the BCR-ABL gene and consequently get it down to deeper molecular levels (like MR4 etc) in less time, but they also have potentially more grade 3 and 4 side effects than imatinib (particularly cardiac effects in those who may have existing or unidentified conditions) so there is a trade off that we should be aware of. There is always risk, no matter what.
Of course, not everyone has the goal to stop therapy and a lot of people are content to stay on therapy as long as quality of life is not an issue. But for younger people, say under 45, as well as those who may be older but continue to work or lead active lives etc. TFR might well be a reasonable goal for them.
Long term low grade side effects and maybe for some, coupled with additional treatments for co-morbidities can put a bit of a strain on quality of life. In my opinion, if stable deeper MRs are there then it can do no harm to at least discuss with doctors the pros and cons of joining one of the stopping studies, of which there are many currently recruiting in Europe, including the UK (DESTINY).
Of course TFR, as I said, will only be achievable for between 9-15% of first line imatinib users, but with 2nd gen TKIs now being used as first line therapy, we may see an increase in that percentage in the future.
Having been TKI free since a year after my SCT in 2003, I can see both sides of the issue of to stop or not to stop, especially as my PCRs have now been at a low positive for around 18 months and are consistently at MR5 (0.001%). It seems that my immune system is perfectly capable of controlling the BCR-ABL gene and although it is there if you look hard enough, it is unlikely to cause me any problem in future, so I am comfortable in my TFR.
Someone at the meeting I attended mentioned that if you tested the whole population of any country, you would be likely to find some level of BCR-ABL in 70%, but for some unknown reason this abnormality does not go on to develop into CML. Curious but fascinating.
Good luck with getting your B12 up to normal levels.
Sandy