Second-line sunitinib for Chinese patients with advanced gastrointestinal stromal tumor: 37.5 mg schedule outperformed 50 mg schedule in adherence and prognosis

BACKGROUND: Sunitinib is widely accepted as a second-line treatment for advanced gastrointestinal stromal tumor (GIST). This study aimed to evaluate patients’ adherence to sunitinib treatment and optimize the dosing schedule for Chinese patients. METHODS: The present study analyzed medical data of patients with advanced GIST treated in Shanghai Ruijin Hospital and Shaoxin Shangyu People’s Hospital. Adherence to sunitinib was evaluated through questionnaires. Treatment outcomes were evaluated during follow-up. RESULTS: Medical data of 107 patients were included in the analysis. The overall progression free survival (PFS) was 41 weeks (95% CI: 39.0–43.0 weeks), and overall survival (OS) was 70 weeks (95% CI: 68.1–71.9 weeks). Sixty-five patients completed the questionnaire evaluation of sunitinib adherence. Patients with good adherence had longer PFS than patients with poor adherence (P=0.032). Patients following the 37.5 mg continuous daily dosage (CDD) schedule had significantly longer PFS and OS than those following the 50 mg “4-week on 2-week off” schedule (50 mg 4/2 schedule), (P=0.044, and 0.016 respectively). Meanwhile, 64.1% of patients following the 50 mg 4/2 schedule suffered severe treatment toxicity Grade 2–3, and this percentage was significantly higher than that of patients following the 37.5 mg CDD schedule (P=0.010). The 50 mg 4/2 schedule and severe treatment toxicity were independent risk factors related to poor adherence (P=0.039, and 0.006 respectively). CONCLUSIONS: Sunitinib 37.5 mg CDD schedule was related to improved adherence and prognosis compared with 50 mg 4/2 schedule. Sunitinib 37.5 mg CDD schedule might be a more suitable dosage schedule in Chinese patients with advanced GIST after imatinib failure.