Bevacizumab-based Chemotherapy for Poorly-differentiated Neuroendocrine Tumors

Aim: To assess and report the efficacy of and tolerance to bevacizumab-based chemotherapy in treatment outcome of metastatic poorly differentiated neuroendocrine tumors. Patients and Methods: From 2007 to 2018, 11 consecutive patients with metastatic poorly differentiated neuroendocrine treated in first- or second-line with bevacizumab-based chemotherapies were included in this monocentric retrospective cohort. Tumor response was evaluated by computed tomographic scans. Results: Administered treatment included 5-fluorouracil and irinotecan (FOLFIRI) bevacizumab, 5-fluorouracil and oxaliplatin (FOLFOX) bevacizumab and 5-fluorouracil, oxaliplatin and irinotecan (FOLFIRINOX) bevacizumab for four, two and five patients, respectively. Three were treated in first-line and eight in second-line after cisplatin-etoposide regimen. Using Response Evaluation Criteria in Solid Tumors, partial response was observed for seven patients, and stable disease for one patient, giving a response rate of 63.6% (95% confidence interval=35 .2-92.1%) and disease control rate of 72.7% (95% confidence interval=46 .6-99 .0%). All patients had died by the time of analysis, median progression free survival was 14 months, and median overall survival was 15.3 months. Observed toxicity with such protocols was classical with 10 grade 3-4 toxic events, including three of hematological toxicity, three of infection, and three of digestive toxicity. Conclusion: Bevacizumab-based chemotherapy gave surprising efficacy and safety in first-or second-line treatment for metastatic poorly differentiated neuroendocrine tumor in this retrospective cohort. Prospective randomized trials of such therapy are warranted.