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Thyroid eye disease drug meets primary endpoint for proptosis reduction
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Top-line results from the OPTIC trial showed that the phase 3 study met its primary endpoint, demonstrating that more patients with active thyroid eye disease assigned teprotumumab experienced a meaningful improvement in proptosis, or protrusion of the eyeball, compared with patients assigned placebo, according to a press release from Horizon Pharma.
In the study, designed to investigate the efficacy, tolerability and safety of teprotumumab in patients with active thyroid eye disease, researchers assigned 83 patients to teprotumumab or placebo in eight IV infusions (10 mg/kg for the first infusion followed by 20 mg/kg for the remaining seven infusions) every 3 weeks for 21 weeks, according to the release. The primary endpoint was a 2 mm or more reduction of proptosis in the study eye, without deterioration in the fellow eye, at week 24. Proptosis is the main cause of morbidity in thyroid eye disease.
In the intent-to-treat population, 82.9% of patients assigned teprotumumab and 9.5% patients assigned placebo were proptosis responders at week 24 (P < .001), according to researchers.
“The dramatic results of the teprotumumab phase 3 confirmatory trial, in addition to positive phase 2 data, form a highly convincing body of clinical evidence supporting teprotumumab for the treatment of active thyroid eye disease,” Timothy P. Walbert, chairman, president and CEO of Horizon Pharma, said in the release. “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. We are one step closer to delivering the first FDA-approved treatment to people living with active thyroid eye disease, and we are grateful to the patients, physicians and investigational sites who have partnered with Horizon to make the teprotumumab research and development program possible.”
All secondary endpoints were also met, including a 2-point or greater reduction in clinical activity score by week 24 and a 2-mm or greater reduction in proptosis from baseline, provided there is no corresponding deterioration in the fellow eye, according to the release.
The safety profile of teprotumumab in OPTIC was similar to that seen in the phase 2 study with no new safety observations. The dropout rate was low (< 5%) and balanced across placebo and treatment arms. There were no deaths during the study and three serious adverse events, including one infusion reaction that led to discontinuation of the study drug, according to the release.
“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,” Raymond Douglas, MD, PhD, director of the orbital and thyroid eye disease program at Cedars-Sinai Medical Center and a co-principal investigator of the phase 3 study, said in the release. “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.”
The company said it expects to submit a biologics license application to the FDA in mid-2019. Teprotumumab has received breakthrough therapy, orphan drug and fast track designations from the FDA.
Horizon said detailed phase 3 data will be submitted for publication in a peer-reviewed journal and presented at a medical congress later this year.
Disclosure: Walbert reports he is chairman, president and CEO of Horizon Pharma.