Horizon Pharma says it has completed enrollment in a confirmatory Phase III trial of teprotumumab in patients living with moderate-to-severe active thyroid eye disease (TED) ahead of schedule.

TED is a rare autoimmune disease in which the insulin-like growth factor receptor (IGF-1R) is overexpressed on eye tissues, causing local inflammation, orbital fibroblast proliferation and tissue expansion, which can in turn lead to proptosis, or bulging of the eye.

The Phase III study (NCT03298867), which enrolled 83 patients at 13 sites across the US, Germany and Italy, will be randomise patients to receive either eight infusions of teprotumumab or placebo every three weeks for 21 weeks.

The primary endpoint is the responder rate of ≥ 2 mm reduction of proptosis, or bulging of the eye, at week 24, in teprotumumab treated versus those in the placebo arm.

Topline results are expected in the second quarter of 2019.

“Our success in rapidly enrolling this trial speaks to the significant unmet need and the strong collaboration with Phase III study investigators,” said Timothy Walbert, Horizon’s chairman, president and chief executive.

“There is no FDA-approved therapy for TED, which can result in bulging of the eyes, known as proptosis, and cause additional challenges for those living with the disease. Completing enrollment in our confirmatory Phase III trial marks a key milestone for people living with TED and Horizon Pharma.”