The first treatment for a rare disease that causes eye bulging and double vision received an FDA nod on Tuesday, weeks ahead of the agency’s March 8 deadline to review the drug.
Dublin, Ireland-based Horizon Therapeutics (NASDAQ: HZNP) tested the medicine, teprotumumab-trbw (Tepezza), in thyroid eye disease, which occurs when the muscles and fatty tissues behind the eye become inflamed, causing the eyes to be pushed forward and bulge outwards. In addition to causing physical discomfort and impaired vision that can impair daily activities, the autoimmune condition can also cause facial disfigurement.
In two studies enrolling 170 patients with active thyroid eye disease randomized to receive either the test drug or a placebo, 71 percent and 83 percent of patients who received the drug had eye protrusion reduced by more than 2 millimeters compared to 20 percent and 10 percent of those who received placebo, respectively, according to the FDA. In addition to achieving the studies’ main goal, secondary goals were also met, including an improvement in double vision.
Teprotumumab works by blocking a growth factor known as IGF-1R. It’s the first FDA-approved treatment option for thyroid eye disease, which progresses to an inactive form of the condition over about one to three years, but can later require surgeries to reverse the damage caused during that active period, including vision impairment.
The medicine is administered via eight infusions that take about an hour to 90 minutes, delivered every three weeks over a six-month period, CEO Tim Walbert said on a conference call following the FDA’s OK. He said the average net price for teprotumumab will be about $200,000.
The company aims to treat 15,000 to 20,000 people yearly in the US, Horizon’s estimate of the subset of those with active thyroid eye disease whose condition is moderate to severe, Walbert said on the conference call. The FDA approval, however, made the drug eligible for all patients with the disease. The agency said prescribers should monitor patients with inflammatory bowel disease who receive the drug for an exacerbation of IBD; some patients in the clinical trials experienced hyperglycemia, or increased blood glucose, so the FDA advised monitoring patients for symptoms of elevated blood glucose too.
Patients’ most common reported adverse reactions were muscle spasm, nausea, hair loss, diarrhea, fatigue, hyperglycemia, hearing impairment, an altered sense of taste, headache, and dry skin.
Teprotumumab’s approval didn’t come as a surprise given that last month an advisory committee to the FDA unanimously recommended the agency approve the drug. However, Horizon must continue to study teprotumumab in a larger group of patients because of designations the FDA awarded the company, given the lack of treatments for the condition, which sped up the review of the treatment on a slimmer body of evidence than otherwise would be required.
Horizon acquired the drug in 2017 when it bought River Vision Development—launched solely to develop the drug, which was initially developed by Denmark’s Genmab (NASDAQ: GMAB) and licensed from Roche—for $145 million up front, plus potential milestone payments. The Irish pharma will pay about $105 million in milestone payments related to teprotumumab in the first half of 2020. At the time of the acquisition Horizon anticipated peak annual sales would be about $250 million in the US. Horizon later increased that estimate to about $750 million, then, last week, to more than $1 billion.
It based the change on a better understanding of the market based on its research and preparation for the drug’s launch, plus the “dramatic” results from its Phase 3 trial.
Horizon anticipates the drug will become available in the coming weeks.