Efficacy and safety of sunitinib in Chinese patients with imatinib-resistant or -intolerant gastrointestinal stromal tumors

Aims: To assess the efficacy and safety of sunitinib in Chinese patients with imatinib-resistant or -intolerant gastrointestinal stromal tumors (GISTs), and evaluate the impact of genotype on sunitinib efficacy. Materials & methods: In a single-arm retrospective study, 55 patients with recurrent or metastatic GISTs who were resistant or intolerant to prior imatinib treatment received sunitinib for at least one treatment cycle. Results: The median progression-free survival was 35 weeks (95% CI: 24.6-45.4) in patients who received sunitinib 37.5 mg/day as a continuous daily dose versus 30 weeks (95% Cl: 12.8-47.2) in those who received sunitinib 50 mg/day as a 4-weeks-on, 2-weeks-off (4/2) schedule (p = 0.707). The median overall survival of all patients was 86 weeks (95% Cl: 75.0-97.0). Patients with KIT exon 9 mutations had a significantly longer progression-free survival compared with those with KITexon 11 mutations and patients with wild-type GISTs (p = 0.022). Sunitinib therapy was well tolerated, with most adverse events rated as grade 1 or 2 in severity. The sunitinib 37.5 mg/day continuous daily dose schedule was better tolerated by Chinese GIST patients than the 50 mg/day 4/2 schedule. Conclusion: Sunitinib was effective and well tolerated in Chinese patients with imatinib-resistant or -intolerant GISTs. Patients with KIT exon 9 mutations showed the best efficacy. A 37.5 mg/day continuous daily dose sunitinib dosing schedule appears to be the optimal choice for Chinese patients due to a decreased incidence of adverse events.