Depressing news here, and I need advice. I am now on my fourth pleural effusion and second Sprycel break. The onc is talking about switching to Bosutinib. He's willing to start at a reduced dose since I have been at < 0.01% IS for awhile, in an effort to lessen the diarrhea and elevated liver enzymes that are common Bosutinib side effects. But I am reluctant to move to a new drug, particularly one that's only been around since 2012. The Phase 3 trial only followed 200-odd patients in the Bosutinib arm. There have been case studies in which pleural effusions continued under Bosutinib, with PAH developing, to boot. Although it doesn't target cKIT or PDGFR, it does target the SRC family of kinases, and they could contribute to pleural effusions. Plus . . . diarrhea! Need I say more? Gleevec permanently screwed up my kidney values, but the old liver is doing just fine - why mess with that?
What I would like to do is reduce my Sprycel further (I currently am on 50 mg, which obviously didn't keep the pleural effusion away) to 20 mg, plus I'd like to experiment with intermittent dosing. I'm 66 and have been taking TKI's for 8 years. I've been MMR or below for 6 years; MR4 (except for the break) for a year or two. It's going to be a fight; he's a believer in "underdosing" breeds resistance. But I have a lot of literature and research to cite; I just dread the confrontation.
What should I do? I have some specific questions: What would be a good starting dose if I did choose the Bosutinib? If I could persuade him to go down to 20 mg Sprycel, what would be a good intermittent plan? 5 days a week on with the weekends off? Every other day? One week on, one week off? And, most importantly, if my PCR continued to be at or below 0.01, would that "prove" there was no resistance developing?
Trey and Scuba, especially, but everybody: please weigh in and help me figure this out. I'm wondering if I could email Dr. Cortes, since I know he's OK with 20 mg Sprycel for patients, and he worked on Bosutinib.
Thanks in advance!