I was PCRU in less than a year, remained PCRU for about 3 years, then went from 400mg Gleevec down to 200mg and have remained PCRU for 4 years while on 200mg. Side effects are minimal on 200mg Gleevec. Still have occasional muscle cramps and some scalp itching. I think the continued side effects help show that 200mg is a dosage that has impact.
I believe it is a low risk strategy, and better than stopping drugs entirely which is an approved strategy by some Oncs under certain conditions. So if stopping is acceptable, why not reduced dosage, also? Those who think a lower dosage invites developing resistance are deluded, in my opinion. TKI drugs are nothing like antibiotics which can train a bacteria to defeat it in low dosages. And some Oncs now regularly use lower dosage such as Dr Cortes at MD Anderson.
The theory that led me to do this (on my own without my Onc's agreement) is that after several years of PCRU we are only trying to keep a "handful" of leukemic cells under control. So if 400mg works well when our blood is full of leukemic cells, why would we need 400mg when we have only a few remaining leukemic cells to keep under control? I think 3 years PCRU is the right timing. I also think that the person should be a "quick responder", meaning they achieved MMR and PCRU fairly quickly. This shows that the person has unusually good absorption and cellular uptake of the TKI drug. So a lower dosage actually acts like a higher dosage would for most other people. That combined with the better than average uptake of the drug allows for taking a lower TKI drug dosage in very low state minimum residual disease.
I have PCRs and blood tests every 6 months. For me this lower dosage has been the right approach. I can't say it is right for everyone.