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Low WBC and sensitivity to TKIs


Hi all,

ive been diagnosed with CML  back in Sept 2017. Was first put on hydroxyurea then started on Nilotinib. However after a week into Nilotinib, my liver function test went up very high that my doctor ordered me to stop Nilotinib. A week later I was asked to turn on Imatinib 400mg. As I am also having some problems with my uric levels, I also had to take Allopurinol. 1.5 months into Imatinib, my WBC became very low (2.2). So my doc asked me to Change to 300mg per day. She told me that anything below 300mg, the body would start to build resistance.

my question: what does extreme low WBC means?how will it impact my PCR results? My doc said I’m a special case which develops high sensitivity to TKIs...



Hi John, 

your overall white cell count is lower than the normal ref count but given you are being treated with TKI therapy (and so recently diagnosed) your white cell count will be lower than the 'normal' range (ie. for healthy adults) and shows you are responding to therapy. I am not sure why your doctor is so worried about a white count of 2.2 but that may be because of your individual case. I advise you to look at the 'About CML'  page and scroll down to 'testing for CML' where you will find lots of info on the various tests including blood cell counts. I have copied a para from that page below which I hope will help allay any worries you have.


When are low counts cause for concern?
The answer to that question depends somewhat on the individual patient, the larger clinical picture and the therapy received. In general, for patients on imatinib mesylate therapy ( Gleevec or Glivec ), the following levels may warrant a decrease in dose, an interruption of therapy or the use of growth factors : WBC less than 1.0 k/ul; platelets less than 50 k/ul; hemoglobin less than 10.0 gm/dL; and ANC less than 1.0 k/ul.

Hi John. Low WBC on imatinib has been my experience since I was diagnosed in 2007.

I always had low wbc, first investigated in the 1980s when I had a testicular cancer. (it is likely that the radiotherapy I had at  that time is behind my CML) I survive quite happily on a WBC of around 2. I carry a stock of broad spectrum antibiotics but seldom have to use them - more likely to get them replaced when they go out of date. In the early  days I was on 400mg Imatinib and my consultant got worried and for a few months cut my imatinib to 200mg, but this slowed down the progression on my BCR-ABL so we went back to 400mg and I got to MMR in about 18 months. Have been stable for around 10 years.

Knowing what I know now, in your shoes I would ask my consultant to get my imatinib blood levels checked on the lower dose to see if I was still in the therapeutic zone.This has become available in the last few years -  Kings College Hospital provide this service to the NHS see this link

I hope this is useful

best wishes