Medication Summary
Somatostatin reduces serum vasoactive intestinal polypeptide (VIP) levels and controls diarrhea in patients with VIPomas. To circumvent the short serum half-life of somatostatin, the derivative octreotide is used. An available long-acting formulation of octreotide allows once-monthly intragluteal administration. Long-term treatment with octreotide often causes resistance to the drug. When maximum tolerable octreotide doses cannot control symptoms, interferon alfa may be added to control diarrhea.
Glucocorticoids are less effective but also less expensive.
Somatostatin Analogues
Class Summary
Somatostatin analogues may control diarrheal symptoms in as many as 80% of patients with unresectable or metastatic tumors. High-dose treatment may lead to additional, antiproliferative effects. However, long-term application of somatostatin may downregulate receptor expression levels, resulting in decreased efficiency despite increasing doses. Short-acting and long-acting depot preparations are available.
Octreotide acetate (Sandostatin, Sandostatin LAR)
Octreotide acetate acts similarly to the natural hormone somatostatin and has the ability to suppress the secretion of gastroenteropancreatic peptides, including VIP. Octreotide treatment in patients with VIPomas should start with low dosages, which are then titrated on the basis of patient response. Sandostatin LAR is a long-acting depot dosage formulation intended for intramuscular injection.
Lanreotide (Somatuline)
Lanreotide is a long-acting synthetic analogue of somatostatin. It binds to the same receptors as somatostatin but with higher affinity to peripheral receptors. It has a much longer biological half-life than octreotide, and its pharmacological effects are longer than octreotide.
Lanreotide's action is similar to the natural hormone somatostatin, but it is long-acting. It suppresses peptide secretion, including VIP, from gastroenteropancreatic tumors. It controls diarrhea in 80% of patients with unresectable or metastatic tumors. It is available in two formulations: sustained-release Somatuline La for IM injection every 10-14 days, and a depot formulation Somatuline Depot injected SC monthly.
Corticosteroids
Class Summary
Glucocorticoids have anti-inflammatory properties and cause profound and varied metabolic effects, modifying the body’s immune response to diverse stimuli. In the treatment of VIPomas, these agents are less expensive than octreotide but also less effective; they reduce symptoms in approximately 50% of patients.
Prednisone (Rayos)
Prednisone is an immunosuppressant used to treat autoimmune disorders. It may decrease inflammation by reversing increased capillary permeability and suppressing polymorphonuclear leukocyte (PMN) activity. It stabilizes lysosomal membranes and also suppresses lymphocytes and antibody production.
Prednisolone (Pediapred, Prelone, Orapred, Millipred, Flo-Pred)
Prednisolone may decrease inflammation by reversing increased capillary permeability and suppressing PMN activity. It is a commonly used oral agent.
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Patient with a large VIPoma. (A) Arteriogram showing vascularity of a large VIPoma preoperatively. (B) Large mass seen intraoperatively. (C) Gross pathologic specimen. Patient subsequently developed liver metastases; he was treated with chemoembolization of liver masses multiple times and finally succumbed to disease 20 years after initial surgical treatment.
