Horizon Pharma's inflammatory eye drug aces phase 3, poised for midyear BLA

Horizon Pharma’s inflammatory eye drug teprotumumab met its primary endpoint in a phase 3 study, with topline data showing the drug beat out placebo in reducing proptosis, or bulging of the eye. The candidate also met its secondary endpoints, and Horizon plans to submit a BLA in mid-2019. 

Teprotumumab is a fully human monoclonal antibody inhibitor of the insulin-like growth factor type 1 receptor. Dublin-based Horizon picked it up in its $145 million acquisition of River Vision in May 2017. The deal came after The New England Journal of Medicine published phase 2 data looking at teprotumumab in patients with recent-onset, moderate-to-severe thyroid eye disease (TED), a rare autoimmune inflammatory disorder. Active TED is characterized by inflammation and tissue expansion behind the eye and can lead to proptosis, strabismus—misalignment of the eyes—and double vision. In some patients, it progresses to blindness. 

The phase 3 data show that after 24 weeks of treatment, 82.9% of teprotumumab patients achieved a 2-mm or greater reduction in proptosis, compared to 9.5% of placebo patients. The drug also outperformed placebo on all the secondary endpoints, which included a decrease in Clinical Activity Score, a change from baseline in a measurement of double vision and a change from baseline in a quality-of-life measure for patients with TED. 

The company’s stock was up 27% on the news. 

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TED is active for about two to three years before it stabilizes. Treatment for the active period “focuses on preserving sight and the integrity of the cornea as well as providing treatment for double vision,” according to the Kellogg Eye Center at Michigan Medicine. Once the disease becomes inactive, patients may then undergo surgery to treat certain symptoms, such as double vision or returning the eye to a normal position in the eye socket. 

“In the study, patients treated with teprotumumab had an unprecedented reduction in proptosis, which is currently only treatable via surgery after the active disease has ended,” said Raymond Douglas, M.D., Ph.D., the study’s co-principal investigator and director of the orbital and thyroid eye disease program at Cedars-Sinai Medical Center, in the statement. “If approved, teprotumumab would give physicians the first medicine shown to reduce proptosis during active thyroid eye disease, in addition to treating other painful symptoms.”  

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“This is a key milestone as we evolve into a research-focused company developing innovative new medicines to address challenging diseases with very few effective options,” said Horizon Pharma CEO Timothy Walbert in the statement. “We are one step closer to delivering the first FDA-approved treatment to people living with active thyroid eye disease.”