Case Series of Metastatic VIPoma With Partial Response to Somatostatin Receptor Ligand and Review of Therapeutic Options

Abstract

Background: Vasoactive intestinal polypeptide secreting islet cell tumors (VIPoma) are rare neuroendocrine tumors of pancreatic origin, characterized by secretory diarrhoea and electrolyte imbalances. Metastasis, commonly hepatic, frequently occur at diagnosis in up to 80% patients. Surgery of the primary tumour remains the gold standard management and in metastatic tumors, somatostatin receptor ligands (SRL) are the drugs of choice for symptom relief and disease control. Some patients will require other approaches to control symptoms, such as liver-targeted therapy, peptide receptor radionuclide therapy (PRRT) or chemotherapy. We describe a case series of metastatic VIPoma which partially-responded to SRL and review of other treatment modalities to achieve disease and symptom control. Case: We report 3 cases, ages 37 to 58 years, with metastatic VIPoma whom presented with secretory diarrhoea, hypokalaemia, achlorhydria and elevated serum VIP levels. CT and 68Gallium PET-CT imaging identified metastases in liver, bone, lungs, spleen and lymph nodes. One case underwent distal pancreatectomy and splenectomy at diagnosis and two cases were advanced and non-resectable. All received long-acting SRL initially and achieved partial control of the gastrointestinal symptoms. Two cases underwent Peptide Receptor Radionuclide Therapy (PRRT) and one case received cytotoxic chemotherapy. Two patients have progressive disease and one succumbed to advanced disease. For inoperable disease, PRRT is useful adjuvant therapy for symptom relief and may improve progression free survival (PFS). Cytotoxic chemotherapy is an option for patients with progressive or symptomatic unresectable tumor. Chemoembolization or liver-targeted therapy are used in liver metastasis for loco-regional control. Alfa-interferon and targeted therapies such as everolimus and sunitinib are other treatment options that can be considered. Conclusion: Metastatic VIPoma remains a challenging disease to manage, requiring multimodal treatment approaches. With timely diagnosis and advancing therapeutic options, more patients can achieve improved symptom and disease control as well as increased survival.