Less than two years after Horizon Pharma $HZNP procured phase III-ready thyroid eye disease (TED) drug teprotumumab for $145 million upfront by acquiring a unit of Narrow River, biotech veteran David Madden’s investment firm — the bet has paid off, as the autoimmune inflammatory disorder drug passed its late-stage test on Thursday.
In TED patients, the eye muscles and fatty tissue behind the eye become inflamed, causing the eyes to appear to be ‘bulging’ and eyelids to become swollen and red, eventually culminating in eye misalignment, double vision and in some cases even blindness — but there is limited window of up to three years during which the condition can be treated without surgical intervention.
Teprotumumab is a monoclonal antibody designed to inhibit insulin-like growth factor 1 receptor (IGF-1R). In the 83-patient phase III trial, 82.9% of patients treated with teprotumumab experienced a meaningful improvement in proptosis or bulging of the eye (a 2 mm or more reduction (p<0.001)) compared to 9.5% of patients on the placebo — meeting the main goal of the study. All the secondary endpoints were also met, the company said.
The rare disease drugmaker is working on submitting a marketing application for teprotumumab by the middle of 2019, it said. The FDA has granted the experimental TED treatment — which was originally developed by Genmab and subsequently licensed from Roche — all the bells and whistles: breakthrough therapy, orphan drug and fast track designations that should make a speedy review likely.
“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,” said Raymond Douglas, the study’s co-principal investigator and director of the orbital and thyroid eye disease program at the Cedars-Sinai Medical Center, in a statement.
If the BLA is accepted, the drug is positioned for launch in the first half of next year — given the possibility of priority review, Jefferies analyst David Steinberg wrote in a note, adding that there are roughly 15,000 to 20,000 active TED US patients eligible for treatment.
Steinberg estimated $500 million in peak sales of the drug by 2024, but added that Horizon management has forecast $750 million, given the drug has secured orphan status and is disease-modifying — potentially paving the way for robust pricing.
Horizon currently sells the drug with the highest price tag in the United States — Actimmune.
“Given the strong execution in the relaunch of Krystexxa (a drug for chronic gout) and now on the cusp of introducing another long duration orphan drug with tepro, we increasingly see HZNP becoming a leader in the rare disease area,” Steinberg wrote.
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