Toxicity of high-activity In-111-Octreotide therapy in patients with disseminated neuroendocrine tumours

Disseminated neuroendocrine tumours are difficult to treat and are generall y not responsive to radiotherapy or chemotherapy. Nuclear medicine techniqu es using a radiolabelled somatostatin analogue, In-111-Octreotide, have bee n used for the diagnosis of neuroendocrine tumours. It has been suggested t hat high activities of such an agent may have a therapeutic effect. The aim s of this study were to assess toxicity and to determine if there had been evidence of efficacy. Eight patients with known disseminated neuroendocrine tumours were enrolled in the study; six had carcinoid tumours, one had a m edullary cell carcinoma of the thyroid and one patient had a malignant gast rinoma. Between 1.3 and 4.6 GBq of In-111-Ochreotide were administered to e ach patient for up to five administrations over 12 months. A total of 23 ad ministrations were given. Tests of vital signs, renal, Liver and endocrine function as well as haematological markers were taken before and after trea tment. The treatment was well tolerated with only one patient suffering fro m a sensation of flushing during the infusion but no changes in vital signs . There was a transient (up to 48 h) drop in circulating lymphocytes in fou r patients and platelets in two patients; no supportive therapy was needed. One patient with severe renal impairment had a slight reduction in glomeru lar filtration rate. We conclude that high-activity In-111-Octreotide is we ll tolerated with low toxicity and can be considered for use in patients wi th disseminated neuroendocrine tumours. Further work is now being performed to assess efficacy. ((C) 2000 Lippincott Williams & Wilkins).