First Treatment for Thyroid Eye Disease Gets FDA Approval

The Food and Drug Administration (FDA) has approved Tepezza™ (teprotumumab-trbw; Horizon Therapeutics) for the treatment of thyroid eye disease.

Tepezza™, a fully human monoclonal antibody, works by binding to insulin-like growth factor 1 receptor and blocking its activation and signaling. The treatment is administered as an intravenous infusion.

The approval of Tepezza™ was supported by data from 2 studies evaluating the safety and efficacy of teprotumumab in a total of 170 patients with active thyroid eye disease. Across both trials, 84 patients were randomized to Tepezza™ and 87 were randomized to placebo. The primary end point was proptosis responder rate at week 24, defined as the percentage of patients with ≥2mm reduction in proptosis in the study eye from baseline, without deterioration in the nonstudy eye (≥2mm increase) in proptosis. 

Results showed a proptosis responder rate of 71% and 83% in Tepezza™-treated patients compared with 20% and 10% with placebo in Study 1 and Study 2, respectively; Tepezza™ was also associated with improvement in the less severely impacted nonstudy eye. 

In addition, a subgroup of patients were evaluated for diplopia, a secondary end point, using a 4-point scale where scores ranged from 0 for no diplopia to 3 for constant diplopia. A diplopia responder was defined as a patient with baseline diplopia >0 and a score of 0 at week 24. Among these patients, 53% of Tepezza™-treated patients (n=35/66) and 25% of placebo-treated patients (n=15/59) were diplopia responders.

Regarding safety, the most common adverse reactions reported were muscle spasm, nausea, alopecia, diarrhea, fatigue, hyperglycemia, hearing impairment, dry skin, dysgeusia and headache.

“Currently, there are very limited treatment options for this potentially debilitating disease,” said Wiley Chambers, MD, deputy director of the Division of Transplant and Ophthalmology Products in the FDA’s Center for Drug Evaluation and Research. “This treatment has the potential to alter the course of the disease, potentially sparing patients from needing multiple invasive surgeries by providing an alternative, non‑surgical treatment option.”

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In December 2019, the FDA’s Dermatologic and Ophthalmic Drugs Advisory Committee voted unanimously (12-0) in favor of the approval of Tepezza™. The Company plans to conduct a post-marketing study to further assess its safety.

The product is expected to be available in the coming weeks as a 500mg lyophilized powder in single-dose vials for reconstitution.

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