They are running trials in the UK (Hammersmith) on people with low levels of CML, under MMR, to see if they can stay at the same level while off the TKI.
That is essentially what I did. I had low level residual disease that fell below 0.01 and was termed "undetected" on a few reports. Once I started my own personal trial (with Dr. oversight and monthly PCR tests), my PCR levels slowly increased, but not in a straight line. One month there was a sharp uptick and then the following month a sharp drop - all within the one log precision of the test and all below MMR. The decision was to continue my personal trial (Dr. was intrigued that I was 'stable'), but when the last two tests showed back to back bump ups, I decided to resume my low level Sprycel (20mg) and "verify" that my 'bouncing' PCR's would fall back down.
And they did, by more than a log. I'm borderline PCRU again just where I was when I tried to stop. (i.e. <0.01%). It took nine months to creep up and two months to fall back. Next test won't be until March and if I am PCRU, I will try cessation again....and then again .... and again ... until it sticks.