Dutch Gastrointestinal Stromal Tumor (GIST) Registry Data Comparing Sunitinib with Imatinib Dose Escalation in Second-Line Advanced Non- KIT Exon 9 Mutated GIST Patients

Background The prognosis of patients with advanced gastrointestinal stromal tumor (GIST) has improved greatly after the introduction of imatinib. However, primary or secondary resistance to imatinib occurs in the majority of patients. Sunitinib is the standard second line treatment in exon-9 mutated GIST. Objective We compared the clinical outcomes of sunitinib with imatinib dose escalation in patients with progressive advanced non- KIT exon 9 mutated GIST after failure of first line imatinib. Patients and Methods A retrospective study was performed, retrieving data from a real-life database (Dutch GIST Registry) including patients with GIST treated with sunitinib or imatinib dose escalation after failure on first line imatinib 400 mg daily. Primary outcome measures were progression free survival (PFS) and overall survival (OS). Results In total, 110 patients were included, 72 (65.5%) patients were treated with sunitinib (group A) and 38 (34.5%) received an imatinib dose escalation (group B). Important prognostic features at baseline, such as tumor size, stage at diagnosis, mitotic count and localization were equally distributed in both groups. No significant difference ( p = 0.88) between median PFS in group A [8.7 months (95% CI 5.6–11.3)] and group B [5.6 months, (95% CI 2.6–8.7)] was observed. Moreover, the OS was similar between group A and group B; 63.2 months and 63.4 months, respectively. Conclusion This study represents a proper sample size cohort containing detailed data on mutational status of patients with advanced GIST. We illustrated that imatinib dose escalation could serve as a good alternative for sunitinib as second-line treatment in patients with a non- KIT exon 9 mutation.