Bevacizumab plus capecitabine in patients with progressive advanced well-differentiated neuroendocrine tumors of the gastro-intestinal (GI-NETs) tract (BETTER trial) - A phase II non-randomised trial

Aim of the study Gastro-intestinal neuroendocrine tumours (GI-NETs) are chemotherapy-resistant tumours. Bevacizumab, an inhibitor of vascular endothelial growth factor (VEGF), has shown promising results in several phase II trials of gastro-entero-pancreatic-NETs. We assessed bevacizumab combined with capecitabine, specifically in GI-NET patients. Patients and methods BEvacizumab in The Treament of neuroEndocrine tumoRs (BETTER) was a multicentre, open-label, non-randomised, two-group phase II trial. Here we present the group of patients with progressive, metastatic, well-differentiated GI-NETs. Patients Eastern Cooperative Oncology Group-performance status (ECOG-PS) ≤ 2, Ki-67 proliferation rate <15% and no prior systemic chemotherapy were treated with bevacizumab (7.5 mg/kg/q3w) and capecitabine (1000 mg/m² twice daily, orally d1-14, resumed on d22) for 6-24 months. The primary end-point was progression-free survival (PFS); secondary end-points included overall survival (OS), response rate, safety and quality of life. Results Of the 49 patients included, 53% were men, median age was 60 years (41-82), primary tumour site was ileal in 82% patients and Ki-67 was <15% in 48 patients and not available for one patient. After a maximum of 24 month follow-up per patient, the median PFS by investigator assessment was 23.4 months [95% confidence interval (CI): 13.2; not reached] and the overall disease control rate was 88% (18% partial response, 70% stable disease). The 2-year survival rate was 85%. Median OS was not reached. The most frequent grade 3-4 adverse events were hypertension (31%), diarrhoea (14%) and hand-foot syndrome (10%). Conclusion The combination of bevacizumab and capecitabine showed clinical activity and a manageable safety profile in the treatment of GI-NETs that warrant confirmation in a randomised phase III trial.