Effects of octreotide treatment on Graves' ophthalmopathy and circulating sICAM-1 levels

Efficacy of octreotide treatment for Graves' ophthalmopathy (GO) and the effects of this treatment on the serum levels of the circulating intercellular adhesion molecule-1 (sICAM-1) were evaluated. Ten patients with GO were treated with octreotide three daily SC injections of 100 micrograms, for 3 months. Octreotide treatment was initiated after restoration of euthyroidism with antithyroid drugs. All patients were treated with methimazole to maintain euthyroidism during the study. Sera were collected from all patients before and 3 months after initiation of the study, and from 20 age- and sex-matched healthy subjects for sICAM-1 measurement. sICAM-1 was measured by a sandwich ELISA method. Proptosis in all patients was evaluated by orbital CT scan before and 3 months after initiation of the study. Two of 10 patients did not respond to octreotide therapy, while the remaining eight patients showed regression or improvement after therapy. Octreotide therapy was particularly successful in patients with soft tissue involvement of GO (class II or III disease). Mean proptosis and ophthalmopathy index scores were significantly decreased after 3 months of octreotide therapy. Mean sICAM-1 levels were significantly higher in patients before octreotide therapy (470.5 +/- 52.6 ng/mL, p < 0.0001) when compared to normal subjects (186.5 +/- 53.3 ng/mL). Mean sICAM-1 levels were significantly decreased 3 months after octreotide therapy (from 478.7 +/- 52.6 to 415 +/- 42.8 ng/mL, p = 0.012) in the 8 patients who responded to therapy. In contrast, sICAM-1 levels remained unchanged or increased in two patients with poor response to octreotide therapy. Our results suggest that octreotide therapy could be a treatment modality in patients with GO. The mechanism by which octreotide acts on GO is not clear. The observed decrease in sICAM-1 levels during octreotide therapy suggests that octreotide may have immunomodulatory properties. Further investigation is needed to determine the optimal dose and duration of octreotide therapy.