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Dasatinib cessation failure. Try Bosutinib or reduced dasatinib dose?

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Hi everyone. I was diagnosed 11/2016 when I was 38 years old. I was treated with 100mg of Dasatinib and was undetectable from 08/2019. Late last year I trialed coming off treatment. The last few months were nothing short of amazing, living free from pain and discomfort is absolutely awesome!! I had suffered badly with bone and muscular pain, fatigue & exhaustion, shortness of breath, no libido, water retention, flushing, digestion problems. (On many occasions during my treatment I asked to lower my dose, to see if it would help reduce side effects but my hematologist refused.) So after an initial increase in bone pain within the first month of stopping dasatinib, all of the above listed problems have gone!! I'm back to swimming kms in the pool, being able to keep my house clean, I started a new job, and can stay on my feet all day long without a rest! I don't have to go to bed early anymore, nor rest during the day.
Unfortunately yesterday I saw my consultant for the first time in 5 months and it turns out I have to start treatment again.So, of course, I am pretty devastated.
Here are my options: 1) 500mg Bosutinib, or 2) 100mg of Dasatinib and once I am undetectable again reduce the dose in hope to curb side effects.
Does anyone have an experience like this who could advise me please? Or has anyone changed from dasatinib to bosutinib around my age (43) who could tell me how it is influencing their life?

Given that you were undetectable, you are an excellent candidate for low dose dasatinib. Your doctor appears not well informed about dasatinib and its pharmokinetic profile in comparison to other TKI's regarding response. All he is doing is prescribing the old standard protocol of 100 mg. In your case, it is too much drug leading to the toxicities and discomfort you feel.

This is important .... in my case, my CML response to dasatinib went UP after my initial dose was LOWERED from 70 mg to 20 mg. I had never taken more than 20 mg per day since then and my bcr-abl levels plummeted. Ultimately I decreased further to 20 mg every other day and eventually stopped drug altogether.

Dasatinib inhibits not just CML but also suppresses immune function. By lowering dose, my immune function (which also attacks cancer) improved while also attacking CML. So finding a correct dose is what is important in dasatinib treatment so that both your immune system and dasatinib are attacking CML.

You should consider resuming your therapy at 20 mg per day and track whether you regain your "undetected" status. You can always increase dose. Also be sure you are supplementing with 400 mg magnesium (citrate or taurate forms) per day to lessen muscular pain. Dasatinib depletes magnesium.

(Approach your doctor by suggesting you want to re-start dasatinib at 20 mg per day and track bcr-abl at 3 months to see how you do. If he refuses, find a new doctor.)

I think that my haematologist is reluctant to reduce my dasatinib dosage because of other factors:

- hit a plateau well short of MMR on imatinib before changing to dasatinib
- snail's pace responder
- transcript type e13a2

Ro6ue1, Thankyou but I don’t think this is relevant to my question. I was undetectable for over 3 years on dasatinib, I’m not now because I stopped treatment.

Thanks scuba. Getting a new doctor isn’t on the cards. Yes I take Mag etc… I just am wondering about people’s experience on Bosutinib compared to Dasatinib? Perhaps a silly question as we all seem to have quite personal & varied responses our treatments. It’s not an easy decision… Better the devil I know, or risk the unknown?