TEPEZZA® (Teprotumumab-trbw) Post-Marketing Requirement Study

This is a double-masked, randomized, parallel-assignment, multicenter trial examining the safety and tolerability of teprotumumab in the treatment of Thyroid Eye Disease (TED) in adult participants. This international, Phase 3b/4 trial is being conducted to fulfill an FDA post-marketing requirement for a descriptive trial to evaluate the safety, efficacy and need for re-treatment of 3 different teprotumumab treatment durations for TED. In addition, serum samples from participants with a Baseline Clinical Activity Score (CAS) ≥3 will be evaluated for biomarkers of disease.

Inclusion Criteria: 1. Written informed consent. 2. Male or female between the ages of 18 and 80 years, inclusive, at Screening. 3. Initial diagnosis of TED within 7 years prior to Screening. 4. Proptosis ≥3 mm from baseline (prior to diagnosis of TED), as estimated by treating physician, and/or proptosis \>3 mm above normal for race and gender. 5. Participants must be euthyroid with the baseline disease under control or have mild hypo or hyperthyroidism (defined as free thyroxine and free triiodothyronine levels \