KIT and gastrointestinal stromal tumor: For metastatic GIST, imatinib was used in doses ranging from 400 to 800 mg, and a higher PFS was observed with the 800-mg dose in GIST with KIT exon 9 mutations, although the number of interruptions were more.30,40 In a Phase 1, dose-finding study of buparlisib in patients with advanced solid tumours, the MTD was determined to be 100 mg.41 In this study, the MTD was 80 mg for buparlisib in combination with 400 mg for imatinib, which was 80% of the MTD of buparlisib as monotherapy (confirmed in Phase 1 studies in patients with solid tumours).