Bevacizumab-based Chemotherapy for Poorly-differentiated Neuroendocrine Tumors

To assess and report the efficacy of and tolerance to bevacizumab-based chemotherapy in treatment outcome of metastatic poorly differentiated neuroendocrine tumors.

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.

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.

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.