Initiation of phase III clinical trial (OPTIC-J) in Japan evaluating teprotumumab for the treatment of active thyroid eye disease (TED).

TED is a serious, progressive and potentially vision-threatening rare autoimmune disease that can cause proptosis (eye bulging), diplopia (double vision), eye pain, redness and swelling.

Teprotumumab, marketed under the brand name Tepezza in the United States was approved by the FDA in January 2020 as the first and only medicine for TED, and received Priority Review, Orphan Drug, Fast Track and Breakthrough Therapy designations. Teprotumumab has not been approved for commercial use in Japan.

The OPTIC-J trial is a randomized, double-masked, placebo-controlled, parallel-group study that will evaluate the efficacy, tolerability and safety of teprotumumab in the treatment of patients in Japan with moderate-to-severe active TED. The trial methodology is based on the OPTIC Phase III trial conducted in the United States and Europe and will include approximately 50 adults who meet the trial eligibility criteria at trial sites across Japan. Patients will be randomized in a 1:1 ratio to receive teprotumumab or placebo once every three weeks for a total of eight infusions (10 mg/kg for the first infusion and 20 mg/kg for the remaining seven infusions). This dosage and administration are based on approval in the United States and may not be the same if approved in Japan.

The primary efficacy endpoint is proptosis response rate at Week 24, measured by the percentage of participants with at least a 2 mm reduction in proptosis from baseline in the study eye, without deterioration in the fellow eye less than 2 mm increase). The trial will also assess overall responder rate, the percentage of patients with a Clinical Activity Score (CAS) of 0 or 1 at Week 24 in the study eye, change from baseline at Week 24 in proptosis measurement in the study eye, diplopia responder rate, and the change from baseline to Week 24 in the Graves’ Ophthalmopathy Quality of Life (GO-QoL) questionnaire. Study participants who complete the treatment period and are proptosis non-responders at Week 24 or relapse during the 48-week follow-up may choose to enter an open-label extension period to receive an additional eight infusions of teprotumumab.