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BCR results trending in the wrong direction


Hi all,

I'm writing on behalf of my mother who was diagnosed with CML in February of 2020. She started on Imatinib which she could not tolerate and which didn't work, so was switched to Dasatinib in July of 2020. It worked well right away, but she has not sustained an MMR yet in the ~18 months she's been on it, below are her recent numbers. She progressed over the year toward a log reduction of 3.1, which we thought was great, but she has since declined slightly.

I'm wondering if anyone has similar long term experience with this and if it is recommended she try another drug? I read about chances of "progression free survival" and worry that the drug will stop working for her. Thank you in advance and for this forum which I have found to be very helpful! 

  • September 2021 - 3.1 log reduction, .087% 
  • October 2021 - 2.9 log reduction, .128%
  • December 2021 - 2.8 log reduction, .155%


Hi Nicole,

These sort of blips can happen. It’s of course not ideal, and while almost all scientific literature gives a number of 0.1% as strongly associated with progression free survival there are plenty of people hovering around 1% who continue to do well - this is what an expert CML doctor in the UK has told me. 

I guess what I am saying is that there is absolutely no imminent danger for your mother with this recent slight uptick. It is over a fairly short period so if I were you I would be tempted to hold firm for a while more.

Also, it’s probably a good idea to have some system in place to ensure your mother is 100% adherent to her medication if you aren’t already doing this. Has anything else changes in recent months for any other medication she’s taking?


Hi David,

Thanks so much for your reply! I do believe she is adhering to her medication, although I know I can't be certain as I don't live with her. But she is very focused on keeping the CML under control. As far as I know she has not had any other medical changes that would explain this, she got her Covid booster in the fall but I haven't seen too much about that affecting numbers. 

Thank you! 


Purely anecdotal - but there was a poll on a Facebook group recently about PCR numbers following vaccinations and there didn’t seem to be any reason to think the vaccinations affected results. Not a scientific study of course.

Great that she’s focused on it - which as you say probably means she is highly adherent. May numbers have gone up and down over the years but I totally get when that goes over the MMR threshold it’s more worrying. But I still do think there’s plenty of scope to stay as things are for a while longer … you never know, the next result might have a big drop. 

Very lastly, do you know if these results are on the International Scale? 


Hi David,

I just double checked (we are in the US if that changes anything) and next to her results it does say "BCR-ABL1/ABL1 (% IS)" which I assume stands for International Scale? I admit I haven't looked into that before so I'm not sure! 

Great - that means it’s international standard, which makes it simple to compare to treatment goals. 

Without that there can be a bit of extra maths required.