A randomised, double-masked, placebo-controlled trial evaluating the efficacy and safety of teprotumumab for active thyroid eye disease in Japanese patientsResearch in context

Summary: Background: Teprotumumab significantly improved proptosis and diplopia in patients with active, moderate-to-severe thyroid eye disease (TED) in previous North American and European studies. This is the first evaluation of efficacy and safety of teprotumumab for active, moderate-to-severe TED in Japanese patients. Methods: This randomised, double-masked, placebo-controlled trial was conducted in 16 centres in Japan. Main inclusion criteria were as follows: age 20–80 years; Graves’ disease, in a euthyroid or mild hypo/hyperthyroid state; clinical activity score (CAS) ≥3; moderate-to-severe TED; ≥3-mm increase in proptosis before TED onset and/or proptosis ≥18 mm at baseline; and TED duration ≤9 months. Patients were randomised (1:1, stratified by smoking status) to either teprotumumab or placebo. Patients received eight intravenous infusions, one every three weeks for 24 weeks. Patients, investigators, site personnel (except formulating pharmacists) were masked. Primary endpoint was proptosis responder rate (percentage of patients with ≥2-mm proptosis reduction from baseline) at week 24 in the intent-to-treat population. Adverse events were assessed in all patients. This trial was registered at Japan Registry for Clinical Trials (jRCT2031210453). Findings: Fifty-four patients were randomised (teprotumumab, 27; placebo, 27) between February and November 2022. All patients completed the randomised period, although one teprotumumab patient and two placebo patients missed ≥2 doses. At week 24, the proportion of patients with proptosis response was higher in the teprotumumab group (89%, 24/27) compared with the placebo group (11%, 3/27), 95% confidence interval, 61–95; P