This is a multi-center, open-label extension study of HZNP-TEP-301 (NCT03298867) examining the safety and efficacy of teprotumumab in the treatment of TED in adult participants. Participants who complete the 24-week double-masked Treatment Period in Study HZNP-TEP-301 and are proptosis non-responders or are proptosis responders at Week 24 but meet the criteria for re-treatment due to relapse during the Follow-Up Period of HZNP-TEP-301 will be eligible for enrollment.~All participants who choose to participate will receive 8 infusions of teprotumumab (10 mg/kg for the first infusion followed by 20 mg/kg for the remaining 7 infusions) in an open-label fashion. The Baseline (Day 1) Visit of this extension study will occur within 14 days after the final visit of Study HZNP-TEP-301 (Week 24 for proptosis non-responders and up to Week 72 for participants who relapse). During the open-label Treatment Period, study drug infusions are scheduled for Day 1 (Baseline), and Weeks 3, 6, 9, 12, 15, 18, and 21, (with the final visit at Week 24). After completion of the Treatment Period, subjects who were proptosis non-responders in Study HZNP-TEP-301 will enter a 24-week Follow-Up Period during which study drug will not be administered and clinic visits are scheduled for 1, 3, and 6 months (Visits Month 7, 9, and 12) after the Week 24 visit. Subjects will be contacted 6 and 12 months later by phone or email to enquire if any treatment for TED had been received since the last study contact.~Participants who relapse during the Follow-Up Period of HZNP-TEP-301 and choose to enter this extension study will not participate in the Follow-Up Period of this study but will be contacted by phone or email 6 and 12 months after the Week 24 visit.
The overall objective is to evaluate the safety and efficacy of teprotumumab in the treatment of thyroid eye disease (TED) in participants who participated in the lead-in study HZNP-TEP-301 (NCT03298867; OPTIC) and who were either proptosis non-responders at Week 24 of HZNP-TEP-301 or were proptosis responders at Week 24 but met the criteria for re-treatment due to relapse during the Follow-Up Period of HZNP-TEP-301.