8537 Refractory Hypoglycemia Secondary To Metastatic Insulinoma Treated With Novel Insulin Receptor Antibody - A Case Report

Abstract

Abstract Disclosure: J. Lloyd: None. S. Abu Omar: None. L. Lester: None. L. Wilson: None. Introduction: Insulinoma is the most common functional pancreatic neuroendocrine tumor, characterized by hypersecretion of insulin, causing hypoglycemia. Insulinomas are mostly benign, however malignant neoplasms account for 5-10 % of cases. Surgical resection is the preferred treatment for solitary tumor, however metastatic insulinoma requires a more aggressive approach with medications to prevent hypoglycemia, resection of primary tumor, resection of metastasis, and chemoembolization. We describe a case of metastatic insulinoma with refractory hypoglycemia despite treatment with multiple medications, surgical resection of tumor, embolization of liver metastasis and successfully treated with a novel monoclonal antibody that blocks insulin receptor. Clinical Case: 43-year-old female was initially diagnosed with metastatic insulinoma in 2021. The primary tumor was pancreatic with metastasis to the liver. She was treated with surgical resection of the primary tumor and three hepatic embolizations for liver metastasis. She required a progressive number of medications to treat frequent, debilitating hypoglycemia. These medications included diazoxide, verapamil, lanreotide then changed to pasireotide, everolimus, and dexamethasone. Despite these treatments, she experienced refractory hypoglycemia and was admitted to the hospital. She required continuous dextrose infusion up to 100ml/hr of D50. Due to the large volume of fluid from dextrose infusion and other medications, she developed severe edema and AKI and required aggressive diuretic regimens and briefly intermittent CRRT. As there were no additional medications to add and prospects for future liver embolization were limited, we requested use of RZ358 through the manufacturer’s Expanded Patient Access program. This medication is a monoclonal antibody that blocks the insulin receptor to counteract the effects of insulin and thereby reduce hypoglycemia. This mechanism of action is unique from medications used to manage insulinoma induced hypoglycemia. She received her first infusion of RZ358 which she tolerated well. She had baseline elevation of ALP due to liver metastasis with further rise after liver embolizations, most recently 4 weeks prior. There was a rise in ALP levels which stabilized after 3 days. She experienced no significant side effects. For the first time in two months, five days after her first infusion of RZ358, the dextrose infusion could be stopped. She received her second infusion of RZ358 one week after first infusion. She was discharged home in a stable condition shortly after the second infusion. Conclusion: The Insulin receptor blocking monoclonal antibody, RZ358, offers a promising approach to patients with metastatic insulinoma who have refractory hypoglycemia despite maximal medical and surgical therapy. Presentation: 6/1/2024