* https://ashpublications.org/blood/article/136/Supplement%201/3/471908/Th...
* https://ashpublications.org/blood/article/138/Supplement%201/3601/479738...
There is evidence lowering dasatinib dose from the usually prescribed "100 mg" starting dose can indeed lead to better response.
This was certainly the case with me. Like you, I suffered myelosuppression and always had a low neutrophil count while on dasatinib. My doctor (Dr. Jorge Cortes) lowered my dose to 20 mg based on his knowledge (he is a co-author on one of the papers linked above) and my response shot up (PCR fell dramatically). My dose never went above 20 mg.
It does seem counterintuitive as we are often told efficacy is dose dependent (i.e. more drug = better response). This is certainly true with drugs like imatinib up to the toxicity limit. But this is not the case for threshold drugs like dasatinib. Finding the best dose which works is key. Adding more drug does not lead to better response and in some cases, it can lead to a worse response. And in situations where pleural effusion and myelosuppression develop, lower dasaintib dose has proven to be more effective.
What you can consider trying is lower your dose to 50 mg as the papers suggest (with your doctors concurrence) and test your PCR levels after 3 months. If you find that your response has improved, you might even go lower.
It is possible you have a CML clone emerging that is resistant to dasatinib. At 0.2, however, you have time to test if lowering dose can work.
