Teprotumumab (TEPEZZA®) is currently under evaluation by the European Medicines Agency (EMA) for market authorisation and is expected to be approved by the European Commission (EC) in July 2025 for the treatment of patients with moderate-to-severe thyroid eye disease (TED). It is the first monoclonal antibody targeting IGF-1R, blocking its activation and signalling to prevent symptom manifestation, including lid retraction, moderate-to-severe soft tissue involvement, proptosis, and diplopia. In the United States, the Food and Drug Administration (FDA) approved Tepezza® (teprotumumab-trbw) in January 2020 for the treatment of TED.

Three clinical studies (OPTIC, OPTIC-J and OPTIC-X) and an observational study evaluated teprotumumab for moderate-to-severe TED. It significantly improved proptosis response, clinical activity score (CAS), and Graves’ ophthalmopathy-specific quality-of-life scores compared to placebo. The most frequent adverse events included muscle spasms, alopecia, nausea and fatigue. Additionally, 12-15% of teprotumumab patients reported, in some cases, irreparable hearing damage. TED reactivation rates varied from 26% to 29%, and 65.4% experienced a regression. Notably, 33% maintained a sustained response through the 24-month follow-up.

Teprotumumab is a second-line treatment option for moderate-to-severe TED. However, the scientific evidence remains limited, as efficacy has only been tested against a placebo, not against the standard of care. Furthermore, the lack of European registries for TED reinforces the evidence gap. Besides, clinical experts highlighted the importance of interdisciplinary collaborations (e.g., of ophthalmology, endocrinology, nuclear medicine, and surgery) and recommend patient treatment in specialised centres to achieve optimal results. In Austria, approximately 148 patients receive first-line therapy, with about 30% (n=45) requiring additional treatment. Teprotumumab might demonstrate promising potential as a second-line treatment option for these.