Oculis Holding AG said the first patient has been treated in PIONEER-1, a registrational trial evaluating privosegtor (OCS-05), an investigational neuroprotective therapy for acute optic neuritis.

PIONEER-1 is enrolling patients with acute-onset optic neuritis, including those with and without multiple sclerosis (MS). The primary endpoint is the proportion of patients achieving a gain of at least 15 letters from baseline at month 3. The secondary endpoint is mean change in low-contrast visual acuity at month 3. Patients will be followed through month 12 for safety and tolerability.

The trial is part of the PIONEER clinical program, which includes 2 registrational studies of privosegtor in optic neuritis. The FDA has granted privosegtor Breakthrough Therapy designation and agreed under a Special Protocol Assessment that the PIONEER-1 design and planned analysis could support a new drug application, subject to trial results and review of the full submission.

The study follows Oculis’s recent agreement to acquire Accure Therapeutics’s worldwide development and commercial rights to privosegtor. Oculis had licensed the molecule, previously known as ACT-01, from Accure in 2022. The transaction, announced August 10, would replace that licensing arrangement and give Oculis direct control of the rights.

Oculis also plans to submit an investigational new drug application for privosegtor in acute MS relapses in the fourth quarter of 2026.