Background: Pancreatic neuroendocrine tumors (NETs) are rare but are frequently diagnosed at advanced stages and require systemic therapy.
Patients and methods: This multicenter, open-label, phase II study evaluated sunitinib in Japanese patients with well-differentiated pancreatic NET. Patients received sunitinib 37.5 mg/day on a continuous daily dosing (CDD) schedule. The primary endpoint was clinical benefit rate (CBR; percentage of complete responses [CRs] plus partial responses [PRs] plus stable disease [SD] ≥ 24 weeks). Secondary endpoints included objective response rate (ORR), tumor shrinkage, progression-free survival (PFS) probability, safety, pharmacokinetics, and biomarkers.
Results: Twelve patients received treatment. The CBR was 75 % (95 % confidence interval [CI], 43-94) and included 6 patients with a PR and 3 with SD. The ORR was 50 % (95 % CI, 21-79). PFS probability was 91 % (95 % CI, 54-99) at 6 months and 71 % (95 % CI, 34-90) at 12 months. Commonly reported treatment-emergent (all-causality), any-grade adverse events included diarrhea (n=10), hand-foot syndrome and hypertension (both n=8), fatigue and headache (both n=7), and neutropenia (n=6). No deaths on study were reported; one death due to disease progression occurred >28 days after end of treatment. Sunitinib on a CDD schedule resulted in sustained drug concentrations without accumulation across cycles. Tumor responses in all 12 patients did not appear to correlate with decreases in chromogranin A levels.
Conclusions: Sunitinib 37.5 mg/day on a CDD schedule demonstrated antitumor activity in Japanese patients with unresectable, well-differentiated pancreatic NET. Commonly reported adverse events were consistent with the known safety profile of sunitinib.
Trial registration: ClinicalTrials.gov NCT01121562.