Michael Heinrich, MD who presented at ASCO and treats GIST indicated that he tests all patients before he sees them.
5-10% will present with PDGFRa and 75-80% with KIT. (Slide 9 investor presentation at ASCO)
KIT mutation rapidly rises to 90%: to 23% in 2L and 90% in 3L.
BLU285 seems to be effective approaching 100% in GIST PDGFRa D842V. BLU285 also appears to have activity in KIT (56%). Cp 2L sunitinib 7% and 3L regorafenib 5%.
Another factor worth noting is that IF BLU285 maintains that level of activity (56%) in KIT it could displace the current 2L treatments where there is a substantial population of new patients each year. (7,700 slide 11)