Everolimus dramatically improves glycemic control in unresectable metastatic insulinoma: a case report

Hypoglycemia poses a significant management challenge in patients with unresectable metastatic insulinoma. A 57-year-old woman with pancreatic neuroendocrine tumor with multiple liver metastases was referred to our institution. During the clinical course of pancreatic neuroendocrine tumor, she had experienced palpitations, cold sweats and faintness between meals that indicated her tumors had attained the characteristics of an insulinoma, and her quality of life was impacted by frequent hypoglycemic episodes which could not be prevented by conventional therapies. Shortly after the approval of everolimus for pancreatic neuroendocrine tumor in Japan, we began oral administration at 10 mg per day, which produced a rapid and substantial improvement in glycemic control. The serum insulin level decreased dramatically despite the tumor size remaining stable on computed tomography evaluation. Despite a dose reduction of everolimus to 5 mg per day in response to the adverse reaction of interstitial pneumonitis and a subsequent moderate increase in the serum insulin level, the patient has maintained normoglycemia for a year. Everolimus might represent the treatment of choice for unresectable insulinoma in terms of not only tumor stabilization but also glycemic control.