Horizon Pharma PLC's thyroid eye disease drug maintained its effectiveness in patients for nearly a year after completing therapy, according to new follow-up data from a phase 2 trial.
The company released new data for its drug teprotumumab on Oct. 4 during the American Thyroid Association Annual Meeting in Washington, D.C., based on follow-up results from a phase 2 trial. The drug treats moderate-to-severe active thyroid eye disease, which can cause proptosis, or bulging of the eyes. Patients with the disease are also at risk for blindness and ulcers on the cornea.
The drug reduced these symptoms in a majority of patients with active thyroid eye disease for up to 48 weeks after completion of the phase 2 clinical trial. Specifically, the follow-up data found that four weeks after the 24-week treatment period, eye displacement response for patients receiving teprotumumab was 73.8% compared to 13.3% for patients receiving placebo. And at week 72, 53% of the patients who responded to teprotumumab maintained at least a 2 mm improvement relative to baseline.
Teprotumumab is the only medicine currently in clinical development for thyroid eye disease, said Horizon's Senior Vice President of Investor Relations Tina Ventura during an Oct. 4 conference call. Ventura said the follow-up data shows that the drug has a "durable" response.
Data from a phase 3 trial for the drug is expected in the second quarter of 2019, and the medicine should be submitted to the U.S. Food and Drug Administration in mid-2019 if the trial is successful, according to Horizon Head of Research and Development and Chief Scientific Officer Shao-Lee Lin.
Horizon Chief Commercial Officer Vikram Karnani estimates that the annual addressable patient population in the U.S. is between 15,000 and 20,000 patients, which could lead to more than $750 million in annual peak net sales. The drug could launch in 2020, Karnani said.
The company also plans to conduct a follow-up study of the phase 3 trial, with 24 additional weeks of treatment with teprotumumab.
Teprotumumab has received breakthrough therapy, orphan drug and fast-track designations from the FDA.
Horizon Pharma, an Irish biopharmaceutical company, added teprotumumab to its pipeline in May 2017 through the $145 million acquisition of River Vision Development Corp.