Assessment of the Efficacy of Bevacizumab in Combination With Folfiri as Second-line Treatment in Patients Suffering From an Advanced Inoperable Poorly Differentiated Neuroendocrine Carcinoma of an Unknown or Gastroentero-pancreatic Primary Cancer

Poorly differentiated neuroendocrine carcinomas (NEC) are a sub-group of aggressive neuroendocrine neoplasms (NEN). The most common primary sites are broncho-pulmonary and digestive. The gastroentero-pancreatic NECs (GEP-NEC) represent 7-21% of all of the NENs. Recent data on the initial presentation of GEP-NEC have been reported in two retrospective studies and a French cohort study. No standard second-line treatment has been defined for NECs. Despite a very negative prognosis, these NECs have a certain amount of chemosensitivity, close to that of bronchial NECs. Multiple-drug therapies such as Folfiri, or Folfox, or single drug treatments such as temozolomide are the proposed options but with a low level of proof Bevacizumab associated with a cytotoxic chemotherapy has shown promising results in well differentiated neuroendocrine tumors (NET), known for being hypervascular. The efficacy of bevacizumab has also been suggested in patients with NEC, but never in the context of a phase II study. Its combination with Folfiri is efficient and well tolerated in metastatic colorectal cancer. The combination Folfiri-bevacizumab potentially represents an optimized treatment compared to chemotherapy with only Folfiri. No phase II or III studies have reported results for these patients, and no on-going phase II or III trial have been identified to date. The main objective of this study is to show that, after the failure of a first-line chemotherapy using platinum-etoposide, the combination Folfiri-bevacizumab allows significant prolongation of overall survival in adult patients with GEP-NEC.