Efficacy and Safety of Sunitinib in Patients with Well-Differentiated Pancreatic Neuroendocrine Tumours

Background: In a phase III study, sunitinib led to a significant increase in progression-free survival (PFS) versus placebo in patients with pancreatic neuroendocrine tumours (panNETs). This study was a post-marketing commitment to support the phase III data. Methods: In this ongoing, open-label, phase IV trial (NCT01525550), patients with progressive, advanced unresectable/metastatic, well-differentiated panNETs received continuous sunitinib 37.5 mg once daily. Eligibility criteria were similar to those of the phase III study. The primary endpoint was investigator-assessed PFS per Response Evaluation Criteria in Solid Tumours v1.0 (RECIST). Other endpoints included PFS per Choi criteria, overall survival (OS), objective response rate (ORR), and adverse events (AEs). Results: Sixty-one treatment-naive and 45 previously treated patients received sunitinib. By March 19, 2016, 82 (77%) patients had discontinued treatment, mainly due to disease progression. Median treatment duration was 11.7 months. Investigator-assessed median PFS per RECIST (95% confidence interval [CI]) was 13.2 months (10.9–16.7): 13.2 (7.4–16.8) and 13.0 (9.2–20.4) in treatment-naive and previously treated patients, respectively. ORR (95% CI) per RECIST was 24.5% (16.7–33.8) in the total population: 21.3% (11.9–33.7) in treatment-naive and 28.9% (16.4–44.3) in previously treated patients. Median OS, although not yet mature, was 37.8 months (95% CI, 33.0–not estimable). The most common treatment-related AEs were neutropenia (53.8%), diarrhoea (46.2%), and leukopenia (43.4%). Conclusions: This phase IV trial confirms sunitinib as an efficacious and safe treatment option in patients with advanced/metastatic, well-differentiated, unresectable panNETs, and supports the phase III study outcomes. AEs were consistent with the known safety profile of sunitinib.