Adjuvant imatinib is associated with a significant reduction in recurrence risk (HR 0.19) and improved overall survival (HR 0.37) in patients with resected KIT exon 9-mutated GIST.
The therapeutic effect of imatinib in this subgroup appears primarily cytostatic, with recurrence risk increasing following the cessation of therapy, as evidenced by time-interaction hazard ratios.
In contrast to the advanced/metastatic setting, evidence from a large international cohort suggests no clinical benefit to adjuvant doses of 800 mg/day compared to the standard 400 mg/day for high-risk exon 9 patients.
Molecular subtyping remains the cornerstone of GIST management, and high-risk patients with KIT exon 9 mutations should be routinely considered for adjuvant treatment.
