Dose and schedule modification are required for long-term continuation of sunitinib in Japanese patients with advanced pancreatic neuroendocrine tumors

Purpose: This study aimed to clarify the efficacy and safety of sunitinib in Japanese patients with pancreatic neuroendocrine tumors (PNET), especially by focusing on dose and schedule modification. Methods: Sixteen patients with advanced PNET treated with sunitinib were reviewed retrospectively. Efficacy was evaluated by progression-free survival (PFS) and objective tumor response. Toxicity profile was assessed regularly. Correlation between relative dose intensity (RDI) and treatment period was also evaluated. Results: The median PFS was 25.8 months, and the probability of PFS at 1-year was 92%. The objective response rate and clinical benefit rate were 44% and 69%, respectively. The common adverse drug reactions (ADRs) were hand-foot syndrome (88%), neutropenia (75%), leucopenia (75%), and diarrhea (63%). Due to the development of severe ADRs, 81% required dose reduction and 31% discontinued sunitinib treatment, respectively. Prolonged treatment period was significantly correlated with decreased RDI (Spearman r = − 0.57, P = 0.022). The median RDI among 9 patients whom continued sunitinib more than 1 year was 49%. Conclusions: Sunitinib showed significant clinical benefit in Japanese patients with advanced PNET in the real-world clinical setting. Successful management of ADRs with appropriate dose reduction and interruption can enable long-term continuation of sunitinib.