Short Background, I am 65 years old. I was diagnosed in 2005 and have been on Gleevec since then, except for a short duration, I tried out 50mg Sprycel, a couple of weeks ago, and did not like them one bit & didn't feel up to the duration of waiting it out. I went back to Gleevec, at least I know what to expect, don't think I can go thru another change with my ange and other chronic illnesses.
From 2005 until I think 2011 ( I would have to go back thru my labs, but I think that is close enough) I was going to an hem/onc, who sent my labs for PCR & FISH to GenCorp N.J. from where I live in Indiana. Yep from very early on, for about 6 years I was PCRU, but strangely my FISH was alway dedectable, but very low. Then all of a sudden I believe in 2011 the PCR jumped up, I can't remember something like 18 % then maybe it was somewhere around 48%, retested right away ( you know they are only looking at a drop of blood & lots of things can go wrong from here, Indiana to Gen Corp in New Jersey) anyhow after last labs were retested at Gen Corp, it dropped back down to somewhere around 12 %. In reality nothing had really changed concerning the CML, only the Lab. Also Novartis sent me a letter, that they would not pay anyone's co-pays for Gleevec, only Tasingna. But never the less, instead of changing drugs right away, like the onc wanted me to, I called Gen Corp, they didn't want to tell me anything, but I kept pressureing them with questions, and yes they had changed over to IS. There were several on the LLS board at that time that were complaining of the same thing. I thought it was rather strange that I at about the same time as my PCR jumped up and onc was pressuring me to change TKI's and also there were others that were on Gleevec, who also recieved a letter that Novartis that they would no longer pay, co-pay for Gleevec, only Tasingna, and their labs had jumped up, lots of patients were freaking out.
For me it was not a big deal about novartis paying co-pays, in that my Insurance (so far) is paying all but a very small co-pay. But it was a big deal when my labs took a sudden jump up, and that I did not want to change TKI's and to much pressure from my onc to change to new/better. I don't know how onc could possible know newer better. I think most literature's says long term side effects.... etc... unknow. I mean you can't know the long term of a new drug that has been out a short time and maybe short clinical trials. Just my opinion.
During all that time I didn't know that there was CML Specilist, at a hospital just 15 miles away, who did their own labs FISH & PCR. Anyhow I changed to the new onc, the new oncologist said he didn't know how I could ever have been PCRU with a positive FISH. I do know the FISH & PCR are done differently, so it probably is the managacture and kit, don't really know? It's funny as I still have strange comparison from FISH / PCR. So there you go, that's the way it works some time, for some folks.
I have had my FISH & PCR done there, locally, for 1 1/2 years now, the results have jumped around from 1% to as high as 13 % and the last one in June 2013, both PCR/FISH were both 3%, so go figure.
However I don't really worry that much about being dedectible +. Being 65 years my quality of life is important to be as well, as long as my other organ's functions such as liver/kidneys etc. My pharmacist will tell me that patients over 65 with other chronic illness should consider a lower dose of whatever. However Oncologist will always come back and say makes you a bigger risk for other things, such as blast, etc. Then I say losing my kidney's liver, etc. and quality of life at my age and other chronic illnesses are big deal to me, too!
I am always mindful of the mother stem cell, one oncologist told me the mother stem cells (from the bone marrow) duplicates 10 to 20 more stem cells, and I don't believe the TKI's ever get that high up to kill those PH+. I think a lot of things are theory and every one is different as to how the TKI'S work with their paticular CML & body and other chronic illnesses.
The above is just my opinion and there are others who have many other theories as to the effectiviness and how the TKI' s work to kill PH+.