Different Response to the Long-Acting Somatostatin Analogues Lanreotide and Octreotide in a Patient with a Malignant Carcinoid

Introduction: Somatostatin (SST) analogues are cornerstones in the symptomatic management of patients suffering from carcinoid tumors, and antiproliferative activity has also been reported for these agents. The most commonly applied SST analogues are octreotide (OCT) and lanreotide (LAN), which are both available in a slow release formulation. To the current knowledge, both OCT and LAN are thought to be equally effective for the management of various disorders. We report the case of a patient with a disseminated carcinoid, who progressed during dose-intensified treatment with slow-release LAN in combination with interferon-α, but developed a pronounced response after treatment was switched to the application of a depot formulation of OCT. Case Report: A 46-year-old woman was admitted to our department for the evaluation of persistent flushing, diarrhea and dyspnea. After a diagnosis of metastatic carcinoid had been established, treatment with LAN (30 mg i.m. every 10 days) along with interferon-α 3 × 5 MU/week was initiated. In spite of successful blocking of tumoral SST receptors as judged by SST receptor scintigraphy and subjective improvement of symptoms, the patient had progressive disease. As she refused chemotherapy, treatment was switched to a depot formulation of OCT (20 mg i.m. every 4 weeks), resulting both in a disappearance of symptoms as well as tumor regression as seen on CT scanning. Conclusion: To our knowledge, this is the first case demonstrating both a symptomatic as well as objective response to OCT following progression during therapy with LAN in a patient with a carcinoid tumor. Our results suggest that refractoriness to treatment including a long-acting SST analogue does not automatically imply resistance to a related agent and should alert clinicians to the potential of non-cross-resistance between SST analogues in neuroendocrine malignancies.