Horizon's thyroid eye disease drug teprotumumab gets backing from FDA panel

Horizon Therapeutics announced Friday that an FDA advisory committee voted 12-0 that the benefits of the experimental drug teprotumumab, a monoclonal antibody directed against IGF-1R, outweigh its risks for the treatment of thyroid eye disease (TED). The company noted that if approved, teprotumumab would be the first treatment for patients with TED, with CEO Timothy Walbert saying the drug "has the potential to address a significant unmet need." 

The agency, which has granted teprotumumab, also known as RG-1507, orphan drug, fast-track and breakthrough therapy designations, is expected to render its decision by March 8, 2020. Analysts estimate the drug could bring in US sales of over $700 million at its peak. 

According to Horizon, its filing is supported by data from the Phase III OPTIC trial, which demonstrated that a significant 82.9% of teprotumumab-treated patients experienced a meaningful improvement in proptosis, versus 9.5% for placebo, with results achieved within a six-month course of therapy. 

Further, all secondary endpoints were also met, including reduced diplopia, improved quality of life and reductions in Clinical Activity Score (CAS), which measures the degree of inflammation, including pain, swelling and redness. In terms of safety, Horizon said the majority of adverse events experienced with teprotumumab were considered to be mild-to-moderate and were managed in the trials, with few discontinuations. 

Teprotumumab was originally developed by Roche and Genmab for multiple indications including sarcoma and non-small-cell lung cancer, with the Swiss drugmaker withdrawing from the partnership in 2009. Genmab later restarted development of teprotumumab in the TED indication, with Horizon eventually gaining the drug in 2017 via the acquisition of River Vision Development Corporation, to whom Roche had licensed it out previously.

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