Horizon Therapeutics plc announced that the U.S. Food and Drug Administration has approved TEPEZZATM (teprotumumab-trbw) for the treatment of Thyroid Eye Disease (TED). TEPEZZA is the first and only FDA-approved medicine for the treatment of TED, a serious, progressive and vision-threatening rare autoimmune disease that is associated with proptosis (eye bulging), diplopia (double vision), blurred vision, pain, inflammation and facial disfigurement. TEPEZZA is a fully human monoclonal antibody (mAb) and a targeted inhibitor of the insulin-like growth factor-1 receptor (IGF-1R) that is administered to patients once every three weeks for a total of eight infusions. The FDA approval of TEPEZZA comes ahead of the Prescription Drug User Fee Act (PDUFA) goal date of March 8, 2020. The medicine received Priority Review, Orphan Drug, Fast Track and Breakthrough Therapy designations from the FDA. The FDA approval of TEPEZZA is supported by a robust body of clinical evidence, including statistically significant, positive results from the Phase 2 clinical study, as well as the Phase 3 confirmatory clinical study OPTIC (Treatment of Graves’ Orbitopathy [Thyroid Eye Disease] to Reduce Proptosis with Teprotumumab Infusions in a Randomized, Placebo-Controlled, Clinical Study). The OPTIC study found that significantly more patients treated with TEPEZZA (82.9%) had a meaningful improvement in proptosis (= 2 mm) as compared with placebo patients (9.5%) (p?0.001) without deterioration in the fellow eye at Week 24. Additional secondary endpoints were also met, including a change from baseline of at least one grade in diplopia (double vision) in 67.9% of patients receiving TEPEZZA compared to 28.6% of patients receiving placebo (p=0.001) at Week 24. In a related analysis of the Phase 2 and Phase 3 clinical studies, there were more patients with complete resolution of diplopia among those treated with TEPEZZA (53%) compared with those treated with placebo (25%). The majority of adverse events experienced with TEPEZZA treatment were graded as mild to moderate and were manageable in the trials, with few discontinuations or therapy interruptions. Horizon will conduct a post-marketing study to evaluate safety in a larger patient population as was discussed at the Dermatologic and Ophthalmic Drugs Advisory Committee (DODAC) FDA Advisory Committee meeting on December 13, 2019, where the committee voted unanimously (12-0) that TEPEZZA demonstrated a positive benefit risk profile. This study will also evaluate retreatment rates relative to how long patients receive the medicine.