INTRODUCTION: Thyroid-associated ophthalmopathy (TAO) is a disfiguring, 
potentially blinding, and sub-optimally managed autoimmune condition. Current 
therapy of active TAO consists most frequently of glucocorticoid steroids, 
orbital radiation, or B-cell depletion; all of which are associated with 
substantial side effects. Teprotumumab (Tepezza) is a human monoclonal antibody 
against the insulin-like growth factor type I receptor (IGF-IR), recently 
evaluated in two clinical trials for active moderate-to-severe TAO that was 
recently approved by the United States Food and Drug Administration (FDA) for 
use in TAO.
AREAS COVERED: This article reviews phase II and III placebo-controlled, 
double-masked, prospective, multicenter studies assessing the efficacy and 
safety of teprotumumab for the treatment of active, moderate-to-severe TAO.
EXPERT OPINION: Teprotumumab has demonstrated substantial and rapid improvement 
in Clinical Activity Score and proptosis reduction in TAO compared to placebo. 
Subjective diplopia and quality of life were also improved in both clinical 
trials. Teprotumumab exhibited a favorable safety profile, with transient 
hyperglycemia, muscle cramps, and auditory side effects being associated with 
the drug; these were usually transient. The trial findings indicate that 
teprotumumab is a promising, potential first-line therapy for treating TAO.