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3-months results reveal that I achieved MMR in the peripheral blood but not CCyR in the bone marrow

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In early June this year, I have diagnosed with CML and I am on Dasatinib 100mg. About a week ago, I got my 3 months BCR-ABL measurements, in the peripheral blood, from 2 different labs (and two different countries) verifying that I've achieved MMR which based on the guidelines is a very good result. So far everything was great. 

As a part of my 3-months tests, I had a bone marrow biopsy as well. Few days ago I received the bone marrow results, where in my surprise it mentions that out of 20 mitigations that have been analysed one had the Ph+ mutation. Does this mean that I haven't achieved CCyR? Or I was unlucky enough the test to "select" and analyse a 1 molecule out of 1000 that has the mutation (since MMR is 0.1% or better). Having less 1% of BCR-ABL in the peripheral blood means that you are expecting the bone marrow to be clear? 

Looking forward for your thoughts. 

L.

Hi,

You are right - it means you are in an unusual situation where your PCR is below 0.1% but you have not yet achieved CCyR. CCyR is usually roughly proxied to a PCR of about 1%.

You may well be right and this test was unlucky enough to select 1 single cell that had the BCR-Abl gene from your marrow. There's no real way to be certain, but that's certainly a very real possibility. Had you had 2 or more then it might be harder to walk past.

David.

I always wondered about this correlation of PCR <1% and CCYR through bone marrow. I always wondered why if the <1% PCR do they even do a bone marrow test if that is the correlation. I realise CCYR is the most important of all milestones and wonder if too much emphasis is on achieving MMR. I also realise for a lot of people this is the case PCR <1% does correlate to CCYR. But in this case it proves not. I was diagnosed with a presenting PCR of only 13% (the lowest I’ve ever seen and still has me suspicious to this day). Last test 0.3% approaching my 18month test which will hopefully be MMR but looking at your story I am worried it may have no correlation to the marrow or it may do. The science and numbers is quite baffling sometimes.

Lets hope it’s a lab error and you are in CCYR. Otherwise MMR prob doesn’t mean a lot.

Keep us updated and all the best.

Alex

Thank you both for your answers. I've called the lab that did the analysis of the bone marrow, since I was curious as well. They've informed me that more than 20 molecules have been tested (that was just the number mentioned in the report) and the one molecule that they found having the abnormality was controversial. The quality of the DNA wasn't good enough to evaluate but they were sure that there was a missing part from chromosome 9, which though wasn't located at chromosome 22. 

Generally the scientist that I talked with, told me that there should be nothing to worry about, she just wanted to mention that into the report in order to repeat the test at six months and be 100% that CCyR has been achieved. Generally from my understanding they've done a lot of effort to find this one molecule and they were not 100% sure that it was Ph+.

I am planning to ask my doctor about the difference of MMR in the peripheral blood and CCyR in bone marrow, so in case I have more information I will let you know.

 

I had a strange result about a year ago too but probably the opposite from this example. My BMB showed 0.11 while blood pcr was around 0.3.....Dont fully understand it but don't really want another BMB.