KIT and gastrointestinal stromal tumor: Progression free survival and OS were significantly higher in KIT exon 9 mutation and WT-GIST subtypes with sunitinib, as well as KIT exon 11 mutations with secondary KIT exon 13 or 14 mutations (14), while secondary KIT exon 17 and 18 mutations involving the KIT activation loop had poor outcomes with sunitinib (60).