Horizon Therapeutics enrolls first patient in TEPEZZA study for chronic TED

Horizon Therapeutics announced Tuesday the enrollment of the first patient in its Phase 4 clinical trial analyzing TEPEZZA® (teprotumumab-trbw), currently the only medicine approved by the Food and Drug Administration (FDA) for the treatment of thyroid eye disease (TED).

The randomized, double-masked, placebo-controlled, parallel-group, multicenter trial will evaluate the efficacy, safety, and tolerability of TEPEZZA® in comparison to a placebo in treating patients with chronic TED, according to a company news release.

“In a number of published case reports and analyses, TEPEZZA® improved (TED) symptoms, including eye bulging (proptosis), when administered in the chronic phase,” said Raymond Douglas, MD, PhD., trial investigator and director of the Orbital and Thyroid Eye Disease Program, Cedars-Sinai Medical Center. “This trial will help us understand these observations in a controlled clinical setting.”

All participants must be 18 years of age or older and have had an initial diagnosis of TED within the last three to at least eight years. They also cannot have had prior orbital irradiation, orbital decompression, or strabismus surgery.

An approximate 60 individuals meeting the trial requirements will be randomized in a 2:1 ration to receive either an infusion of TEPEZZA® or a placebo — 10 mg/kg for the first infusion, 20 mg/kg for the remaining seven infusions, once a week for three weeks, for a total of eight infusions, the company reported.

Primary efficacy endpoint for the trial includes change from baseline at Week 24 in proptosis in the study eye, according to the news release.

Proptosis responder rate and diplopia responder rate as well as changes in orbital pain, muscle volume , and in the Graves’ Ophthalmopathy Quality of Life (GO-QoL) questionnaire appearance and visual functioning subscales will also be assessed.

Participants categorized as proptosis non-responders who have completed the treatment period may elect to enter an open-label extension period and receive eight infusions of TEPEZZA®.

Further information regarding the trial can be found here.