Currently available somatostatin analogs are not good for Graves' orbitopathy

Thyroid eye disease: current and potential medical management

INTRODUCTION

Thyroid eye disease (TED) is the most frequent extra-thyroid manifestation of Graves' disease and it is more frequent in middle age and in female gender. Nowadays, the causal mechanisms of this disease are not completely understood, but the current available studies suggest that the main causative factor is the thyroid stimulating hormone receptor.

MATERIALS AND METHODS

To collect reports on TED medical management, a thorough literature search was performed in PubMed database. An additional search was made in Google Scholar to complete the collected items.

RESULTS

Among the indentified risk factors, tobacco habit is the most relevant. The main criteria to choose a suitable treatment are the activity and severity of the disease. Support measures can be used to improve the patient's symptoms in any phase of the disease. There is a large number of drugs proposed to manage TED, although with different reported rates of success.

CONCLUSIONS

Currently, the drugs of choice are corticosteroids in moderate-to-severe and in sight-threatening forms. The main problem of corticosteroids is their spectrum of side effects. Therefore, other alternatives are being suggested for medical management of this disease. The efficacy of these alternatives remains unclear.

Advances in treatment of active, moderate-to-severe Graves' ophthalmopathy

Graves' ophthalmopathy is defined as autoimmune inflammation of extraocular muscles and orbital fat or connective tissue, usually in patients with Graves' disease. About one in 20 patients with Graves' hyperthyroidism has moderate-to-severe Graves' ophthalmopathy. Corticosteroids have been the mainstay of treatment, but new evidence about immune mechanisms has provided a basis to explore other drug classes. Intravenous methylprednisolone pulses are more effective and better tolerated than oral prednisone in the treatment of active, moderate-to-severe Graves' ophthalmopathy. Rituximab has also been suggested as a possible replacement for intravenous corticosteroids. Two randomised controlled trials of rituximab reached seemingly contradictory conclusions-rituximab was not better with respect to the primary outcome (clinical activity score) than placebo in one trial (which, however, was confounded by rather long Graves' ophthalmopathy duration), but was slightly better than intravenous methylprednisolone pulses in the other (disease flare-ups occurred only in the latter group). On the basis of evidence published so far, rituximab cannot replace intravenous methylprednisolone pulses, but could have a role in corticosteroid-resistant cases. Open-label studies of tumour-necrosis-factor-α blockade had limited efficacy, but other studies showed that interleukin-6 receptor antibodies were effective. Results of randomised controlled trials investigating the efficacy of the IGF-1 receptor antibody teprotumumab and the interleukin-6 receptor antibody tocilizumab are expected shortly. Approaches that target the causal mechanism of Graves' ophthalmopathy (antibodies or antagonists that block thyroid-stimulating-hormone receptors) also look promising.

Perspectives in pharmacological management of Graves' hyperthyroidism and orbitopathy

Drugs currently used for Graves' hyperthyroidism (thionamides) or for the major extrathyroidal expression of Graves' disease, Graves' orbitopathy (systemic glucocorticoids with or without orbital radiotherapy), have limited effects on the autoimmune processes underpinning these disorders. Thionamides show a high rate of treatment failure and at least 30% of patients with Graves' orbitopathy are eventually dissatisfied with treatment outcome. Progress in our understanding of the autoimmune basis of Graves' hyperthyroidism and orbitopathy made it possible, similar to other autoimmune disorders, to envision the use of novel immunomodulating drugs. Among the currently available biologic agents, the CD20(+) B-cell-depleting agent, rituximab, and TNF-alpha inhibitors are the drugs that have the highest chance of finding a place in the treatment of Graves' hyperthyroidism and orbitopathy, although randomized, controlled clinical trials are warranted to support their use.