Bevacizumab combined with 5-FU/streptozocin in patients with progressive metastatic well-differentiated pancreatic endocrine tumours (BETTER trial) - A phase II non-randomised trial

Aim of the study Neuroendocrine tumours are highly vascular neoplasms known to overexpress vascular endothelial growth factor (VEGF) and its receptor. Bevacizumab, an inhibitor of VEGF, was assessed in combination with chemotherapy in pancreatic neuroendocrine tumour (P-NET). Patients and methods BETTER was a multicentre, open-label, non-randomised, two-group phase II trial. Patients with progressive metastatic, well-differentiated P-NET received a minimum of 6 month treatment of bevacizumab at 7.5 mg/kg IV on d1 q3w with 5-FU at 400 mg/m²/day and streptozocin at 500 mg/m²/day IV from d1 to d5 every 42 days. The primary end-point was progression-free survival (PFS); secondary end-points were overall survival (OS), overall response rate, safety and quality of life. Results A total of 34 patients were included. Median age was 55 years, 65% of patients were men, 97% had an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 and 97% had a Ki-67 proliferative index of <15%. After a maximum of 24 month follow-up per patient, the median PFS assessed by investigators was 23.7 months [95% confidence interval (CI): 13.1; not reached], 19 (56%) patients had a partial response and 15 (44%) had stable disease as best response. OS rate at 24 months was 88%. The most frequently reported grade 3-4 adverse events were hypertension (21% patients), abdominal pain (12%) and thromboembolic events (9%). Conclusion Bevacizumab with 5-FU/streptozocin in the treatment of pancreatic NETs seems to be feasible with a PFS of 23.7 months, which deserves further attention. No unexpected toxicity was observed.