FDA grants fast review for Horizon's rare eye disease drug

The FDA has granted a fast review for Horizon Therapeutics’ teprotumumab for active thyroid eye disease (TED), a rare vision-threatening autoimmune condition.

After accepting Horizon’s filing, the FDA granted priority review designation for teprotumumab, meaning the product could be on the market within six months, instead of the standard 10 months.

If approved, teprotumumab would be the first FDA-approved medicine for active TED, and with around 15,000 to 20,000 affected patients in the US the company expects peak sales to exceed $750 million.

The FDA has said it will make a regulatory decision on the drug before March 8 next year, and if no issues arise the regulator will communicate proposed labelling and any post-marketing requests by late December.

As is often the case with novel drugs there will also be an advisory committee meeting to discuss trial results, and the FDA has not identified any potential issues at this early stage of the review.

The filing includes results from a pivotal phase 3 trial, OPTIC, as well as phase 2 trial results.

OPTIC found that significantly more patients with TED treated with teprotumumab had a meaningful improvement in proptosis – bulging of the eye – compared with a placebo group, with 82.9% of patients improving on treatment compared with 9.5% of placebo patients.

All secondary endpoints were also met, including reduced diplopia (double vision), improved quality of life and reductions in Clinical Activity Score.

Teprotumumab was generally well tolerated and the majority of adverse events were mild or moderate, manageable and resolved during or after treatment, Horizon said.

TED is a serious, progressive and vision-threatening autoimmune disease that often occurs in people living with hyperthyroidism or Graves’ disease.

It is caused by autoantibodies activating an insulin-like growth factor receptor (IGF-1R) mediated signalling complex on cells within the eye socket.

This can lead to a cascade of effects that can cause long-term, irreversible damage, such as eye bulging, misalignment of the eyes, double vision, and in some cases blindness.

Teprotumumab works by inhibiting IGF-1R, reducing inflammation and preventing excessive muscle and fat cell expansion in the eye.

Aside from the Priority Review, the FDA also granted Breakthrough Therapy, Fast Track and Orphan Drug designations.