Oxaliplatin and 5-fluorouracil (FOLFOX) in advanced well differentiated digestive neuroendocrine tumors: a multicenter national retrospective study from the French Group of Endocrine Tumors (GTE)

Introduction: Oxaliplatin-based regimens have shown promising antitumor activity in digestive neuroendocrine tumors (NETs); however, the available data are limited. Our aim was to assess the efficacy of FOLFOX (association of 5-fluorouracil with oxaliplatin) in a large series of patients with advanced digestive NETs. Methods: All patients with advanced digestive well-differentiated NETs treated with at least 3 cycles of FOLFOX between January 2004 and December 2018 in 12 centers from the French Group of Endocrine Tumors were included. Tumor response rate according to Response Evaluation Criteria in Solid Tumors version 1.1 criteria, progression free survival (PFS), and overall survival, as well as prognostic factors, were analyzed retrospectively. Results: One hundred fifty-five patients were included. Primary tumor locations were pancreas (n = 89), small intestine (n = 40), unknown with no evidence for lung primary (n = 13), stomach (n = 7), and rectum (n = 6). Median Ki-67 was 10%, and 65% of the tumors were grade 2. The partial response rate was 30% for pancreatic NETs, 12.5% for small intestine NETs, 38.5% for unknown primary NETs, 14% for gastric NETs, and 17% for rectal NETs. Significant prognostic factors for poor PFS after FOLFOX were progressive disease at the beginning of treatment (hazard ratio [HR] = 1.83, p = 0.007), hepatic involvement superior to 50% (HR = 2.67, p = 0.0001), and rectal primary tumor location (HR = 2.6, p = 0.0036). Among pancreatic NETs, insulinomas had a better median PFS (22 months) than other pancreatic NETs (9 months, p = 0.026) and showed a high rate (8/9) of serum glucose normalization. Conclusions: FOLFOX shows a promising antitumor activity in advanced digestive NETs. Rapid symptomatic response is observed in metastatic insulinomas. © 2021