Shares of Acelyrin Inc. fell by more than 36% following the release of Phase II clinical trial data for its drug lonigutamab, developed for the treatment of thyroid eye disease (TED). The market reacted negatively to the news, despite positive trial results.

The company reported “clinically meaningful” improvements, such as reductions in proptosis and double vision. However, investors were concerned about the revised dosing regimen planned for Phase III trials and the modest results compared to competitors.

Lonigutamab is positioned as a competitor to Amgen’s Tepezza, with potentially lower risks of side effects, including hearing loss and hyperglycemia. Despite this, the stock price continued to decline.

Thyroid eye disease is a rare condition causing inflammation behind the eyes. Lonigutamab offers a more convenient subcutaneous administration compared to Tepezza’s infusions and aims to carve out its market niche by 2030.