This randomized, double-masked, placebo-controlled, parallel-group, multicenter trial is evaluating the efficacy, safety and tolerability of TEPEZZA compared to placebo in treating TED patients with a low CAS (1 or less at the screening and baseline visits), two to 10 years since eye symptom onset, and non-worsening proptosis for at least a year. Adult participants who met the trial eligibility criteria were randomized in a 2:1 ratio to receive an infusion of either TEPEZZA or placebo, 10 mg/kg for the first infusion and 20 mg/kg for the remaining seven infusions, once every three weeks, for a total of eight infusions.