It is indeed an interesting case. There are two issues here worth considering which affect what you would do. The first is whether you consider this accelerated phase or blast phase. To me this is accelerated phase. The data we have with TKI comes from studies that have used the standard definition rather than the WHO thus it is somewhat easier to know what to expect. Next is what to do with such patients. For patients with blast phase at any time I would unquestionably advocate SCT even with a good early response. For a patient with blast accelerated phase at the time of diagnosis, we recently published our experience and they do actually quite well, particularly when treated with 2nd generation TKI at the time of diagnosis, with most of our experience coming from nilotinib (only because of administrative reasons where one sponsor allowed us to include AP patients in our frontline studies). So in such a setting, a patient like this I would monitor very closely and see that they meet goals as required. The other side of the equation is the local experience with SCT in this setting. If the expected mortality is low, then SCT makes more sense; if not too low, then clos emonitoring is appropriate. One other thing I would add is that for a patient in blast phase, particularly if I am not going to transplant, I prefer to use TKI in combination with chemo. Currently we are doing combination with decitabine in a clinical trial but outside of the trial I would consider ara-C (low dose if concerned about co-morbidities/age) ± idarubicin.
I hope this helps.
JC