Impact of diabetes and metformin use on enteropancreatic neuroendocrine tumors : Post hoc analysis of the CLARINET study

Simple Summary: Lanreotide was found to be effective for preventing tumors from worsening in patients with neuroendocrine tumors of the intestines and pancreas, regardless of whether or not patients also had diabetes. Metformin, a drug for treating diabetes, also seemed to prevent tumors from worsening. Abstract: The prognostic role of diabetes mellitus (DM) in advanced enteropancreatic neuroendocrine tumors (NETs) is unclear. Progression free survival (PFS) was assessed in post‐hoc analyses of the 96‐week, phase III, double‐blind, placebo‐controlled CLARINET study of lanreotide 120 mg in patients with advanced non‐functional enteropancreatic NETs with DM (with/without metformin) and without DM. Of 204 patients, there were 79 with DM (lanreotide, n = 42 {metformin, n = 14}; placebo, n = 37 {metformin, n = 10}) and 125 without DM (lanreotide, n = 59; placebo, n = 66). Median PFS was 96.0 and 98.0 weeks with and without DM, respectively (hazard ratio 1.20 {95% confidence interval 0.79 to 1.82}; p = 0.380). No difference in PFS was observed in lanreotide‐treated patients with/without DM (p = 0.8476). In the placebo group, median PFS was numerically shorter with versus without DM (p = 0.052) and was significantly longer in patients with DM and metformin (85.7 weeks) versus without metformin (38.7 weeks; p = 0.009). Multivariable Cox analyses showed that DM at baseline was not associated with PFS (p = 0.079); lanreotide was significantly associated with lower disease progression risk (p = 0.017). Lanreotide efficacy was confirmed in patients with advanced enteropancreatic NETs, regardless of diabetic status; DM was not a negative prognostic factor. A potential antitumor effect of metformin was observed in patients receiving placebo.