I had a very similar issue involving neutrophil suppression at 70 mg sprycel (dasatinib). I was taken off treatment until my counts recovered. Then restarted, then had to stop to allow counts to recover and then ultimately stabilized.*
What my doctor did after stopping me the first time is what I suggest your wife consider. He restarted me on 20 mg dasatinib. His research showed lower dose would work better than the higher dose when suppression was occurring. In other words, your wife is likely to have a better response on 20 mg than 70 mg and with less myelosuppression. This is what happened to me. Once on 20 mg, my CML fell back and then plummeted to very low levels and ultimately undetected. I remained at 20 mg for several years but now I am now drug free for over six months with no loss of remission (yet). I have a suspicion your wife could follow a similar path.
(*interestingly my CML levels did not rise much while I was off treatment for about 3 months at that time. But I was by then taking 8 grams of Curcumin per day as well as increasing my vitamin D levels. Your wife can benefit from doing every thing she can to improve her immune health as her CML stabilizes. And it will stabilize and then plummet)