The reason why Gleevec at first was thought to be a niche drug is that the incidence of CML is pretty low - about 4,500 cases per year in the US - and it used to be that all those patients used to die within a year or two, and so the prevalence was maybe 6,000 cases. Once Gleevec arrived on the scene that changed dramatically - CML patients now have a virtually normal life expectancy and so the prevalence of CML patients has dramatically increased. So this is a drug that essentially created its own market - each year the market grows by some 5,000 or so patients (new cases less deaths). (We might see the same phenomenon with ALK inhibitors).
T315I truly is a niche indication, but it is by no means the only indication for pona - it's just the most obvious in that it's known that patients who have this mutation will die without pona. So it provides an essential guarantee that pona will get approved and will be reimbursed in the US and Europe (maybe not the UK). So that's why it's important - not because of its size, but because of its clarity. The initial market for pona will be T315i plus patients that have failed Sprycel or Tasigna plus blast/accelerated phase patients. Some clued-in docs will likely also put some patients that have failed Gleevec on pona, but that will be a small market initially (albeit a growing one).
These sort of sales build slowly, albeit with an initial bolus from the patients continuing from the trial and compassionate use. I'd guess the drug will have a >$50m run rate right out of the gate, but will build relatively slowly from there. Once they get a label for 2nd line, sales will accelerate further.
About a 1/3 of patients fail Gleevec, so the 2nd line market is very significant. But the CML market is fairly sticky - most patients do fine on their existing drug for several years, so it will take some years for pona to realize its full potential. So this is truly a long-term story.
Peter
