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Transient drop of platelets due to Dasatinib


I would like to draw your attention to an "unreported" side effect of dasatinib that might affect someone's treatment plan and lead to discontinuation of Dasatinib due to myelosuppression and low platelets side effect. It is well known that 100mg of dasatinib can be too much for a lot of people causing serious side effects and extreme myelosuppression. I wasn't one of these cases, but generally my platelets dropped once I've started my treatment for CML

After few weeks on Dasatinib, I went to the hospital for the regular blood tests and the doctor suggested that we should stop the medicine for few days due to a virus inflection (not 100% verified, but I had a bit high Lymphocytes) that I had, which might had dropped my platelets and since dasatinib could cause further drop of platelets, the doctor wanted for us to be on the safe side (at that point my platelets were about 60 K/μL). Therefore, I went off dasatinib for few days and the PLTs appeared to get back to normal after 3-4 days.

After 2-3 weeks, once again the blood tests showed low PLTs and the doctor suggested to stop again the dasatinib for few days and then come back with lower dose. At that point, I was convinced that the fluctuation of the PLTs wasn't permanent and should had been caused by something else. Trying to think what might cause this, I found out that I tended to have lower PLTs when my appointment was around 12pm and normal PLTs, when my appointment was before 10pm or after 2pm (I am taking the dasatinib at 10pm). Therefore, I realised that the dasatinib was causing the low PLTs for few hours. I decided to continue my medication and after 3 days when I went to the hospital, I didn't take the medicine till the point I got my blood tests done.. and off course everything was normal. I explained to my doctor, what I have noticed and we decided to stay at 100mg and see how it goes. 

I wanted to be sure that dasatinib was causing this transient drop of platelets and that's why I performed two measurements, in the same Lab as following.

                                   Two Hour before Dasatinib 100mg      Two Hour after Dasatinib 100mg

WBC Total (K/μL)                           9                                                              12.7
Ne (K/μL)                                       6                                                               7.1
Ly (K/μL)                                       1.9                                                              4
Mo (K/μL)                                      0.9                                                            1.2
Eos (K/μL)                                     0.2                                                            0.2
Bas (K/μL)                                     0.0                                                            0.1
RBC (M/μL)                                   4.47                                                          4.48
HGB (g/dl)                                     13.4                                                          14.3
HCT (%)                                        42.1                                                          42.1
PLT (K/μL)                                     185                                                            94
PCT (%)                                        0.137                                                       0.064

I've discussed this with 2-3 different doctors and none was aware that dasatinib could cause that kind of transient side effect. Not sure if anyone else is aware of a similar type of side effect, but it's good for everyone to keep this in mind, since this might play a huge role in our treatment plan and lead to discontinuation, change of medication etc.

I'm really excited about your post. I am currently on 70 mg Dasatinib and suffer from Myelosuppression and low platelets side effect. 

I have an appointment with my consultant this Tuesday and will not take my tablet until after the full blood count and appointment. Usually I take the tablet each morning before breakfast.

I know its not a valid experiment but I would like to avoid either having to come off the Dasatinib or be put on Elthromopag.

Thanks for posting.

Hello Rosiem,

How low are your PLTs in general? What made me try this "experiment" was the fact that some days the PLTs were low (below 75, BUT still above 50) and some others normal (above 150). Delaying my dose for few hours, it's something that I used to do at least once per 2 weeks and it doesn't seem to affect dasatinib's effectiveness since my BCR-ABL measurement is very low (for sure there are plenty of factors affecting how successful will be somenone's treatment). Anyway, I would dare to say that it would be worthy to try delaying your dose for few hours.


I has posted the same in the other thread. Not taking the pill before the blood draw made the difference.