Acelyrin is a pre-revenue, late-stage clinical biopharma company focused on developing lonigutamab for the treatment of Thyroid Eye Disease (TED), a progressive autoimmune condition affecting over 100,000 patients in the U.S. that causes eye bulging, double vision, and in severe cases, blindness. Lonigutamab is a subcutaneously administered monoclonal antibody targeting the IGF-1 receptor, and Acelyrin argues that its subcutaneous delivery offers a meaningful convenience advantage over the only currently approved TED therapy, Tepezza, which is administered intravenously. Acelyrin also argues that lonigutamab's mechanism enables lower drug exposure levels and potential for chronic dosing, which could improve safety and durability relative to Tepezza. Acelyrin completed a Phase 1/2 dose-ranging trial with positive results across proptosis, diplopia, and quality-of-life measures, and completed a positive end-of-Phase 2 meeting with the FDA. The Phase 3 LONGITUDE registrational program had been planned for Q1 2025, but has been delayed pending completion of a merger agreement with Alumis announced in February 2025. Lonigutamab is Acelyrin's sole pipeline asset, following the wind-down of two earlier programs. Acelyrin holds global rights to lonigutamab for non-oncology indications, licensed from Pierre Fabre, and funds operations from its cash balance. If approved, Acelyrin plans to commercialize lonigutamab independently in the U.S. and relies on third-party CMOs for manufacturing.