BACKGROUND
Graves’ disease is a common cause of hyperthyroidism. It is an autoimmune disease in which the person makes antibodies that attack the thyroid gland (TSI or TRAb) and turns on the thyroid, causing an overactive thyroid. This condition can be associated with inflammation of the muscles that control eye movements. This can cause eye bulging (proptosis) and difficulty with eye movements leading to pain, eye irritation, double vision and even loss of vision. These symptoms are known as thyroid eye disease (TED). Moderate to severe cases of TED are typically treated with high doses of glucocorticoids (steroids) and some patients may require surgery to correct the eye changes. In recent years, agents that modify the immune system have been studied as alternative treatments to steroids and surgery. One drug, Teprotumumab, was approved by the FDA in 2020 for the treatment of TED. Patients treated with this medication showed significant improvement in TED symptoms. A second drug, Tocilizumab, has been studied and used off label (not FDA-approved) for TED. This drug works by inhibiting an important immune system mediator known as interleukin-6 and is FDA-approved for other immune mediated disorders. The aim of this study was to report real world experience with these new medical therapies in the treatment of TED at a single medical center in the US.

THE FULL ARTICLE TITLE
Toro-Tobon et al. 2023 Medical therapy in patients with moderate to severe, steroid-resistant, thyroid eye disease. Thyroid. Epub 2023 Jul 29. PMID: 37515425.

SUMMARY OF THE STUDY
This study examines the real-world experience of patients treated with medical therapy for TED at a large, multicenter health system in the US. Patients were identified by screening the electronic medical record database of the Mayo Clinic health system and records reviewed in detail. Adult subjects with TED treated with either teprotumumab (10–20 mg/kg every 3 weeks for a total of eight intravenous infusions) or tocilizumab (4 mg/kg for the first infusion, followed by 8 mg/kg every month, for a total of four intravenous infusions) between 2018-2022 were identified.

Prior treatment with steroids was recorded and it was documented whether patients had progression of TED on steroids (steroid resistant). Overall, 37 patients were identified with moderate to severe TED that had been treated with either teprotumumab (31 patients, 13 steroid resistant and 18 who had not previously received steroids) or tocilizumab (6 patients all with steroid resistance). Eye symptoms were evaluated at baseline, 12, 24, and 52 weeks after medication infusion.

Patients treated with either teprotumumab or tocilizumab reported improved eye symptoms including proptosis and double vision at week 24. Both medications showed a tendency for worsening symptoms at further time points following completion of the therapy. Patients with and without steroid resistance prior teprotumumab therapy demonstrated benefits. Teprotumumab therapy was associated with side effects of ear issues (including hearing loss and ear ringing) and high blood glucose levels. There were no side effects reported in the tocilizumab group, but this group included very few patients (6). The authors concluded that both medications showed promise in improving TED and further studies are needed to better understand their long term benefits and safety, especially in steroid resistant patients.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
Medical therapy may be a good option for TED and importantly may become an alternative treatment to high dose steroids or surgery. Although a small study, both agents, teprotumumab and tocilizumab, were associated with a reduction in TED symptoms. Currently, only Teprotumumab is FDA-approved for the treatment of TED. More studies in larger groups of patients are needed to fully understand the safety and efficacy of these newer medications in the treatment of TED.

— Whitney W. Woodmansee MD

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