ZUG, Switzerland – May 7, 2026
Oculis Holding AG announced that the U.S. Food and Drug Administration (FDA) has granted a Special Protocol Assessment (SPA) agreement for the company’s PIONEER-1 Phase 3 registrational trial evaluating Privosegtor in patients with optic neuritis (ON). The FDA agreement provides formal regulatory alignment on the study design, endpoints, and statistical analysis required to support a future New Drug Application (NDA), subject to successful trial outcomes. The milestone significantly strengthens Oculis’ regulatory pathway as the company advances Privosegtor toward becoming the first neuroprotective therapy for optic neuritis, a serious inflammatory optic nerve disorder that can lead to permanent vision loss.
FDA SPA Strengthens Registrational Pathway for Privosegtor
The FDA’s SPA agreement confirms that the design and planned analysis of the PIONEER-1 study are considered adequate to support a future NDA submission. The Phase 3 trial will evaluate Privosegtor in a broad patient population with optic neuritis, including patients both with and without multiple sclerosis (MS). The primary endpoint will assess the proportion of patients achieving at least a 15-letter improvement in low-contrast visual acuity (LCVA) at Month 3, an established clinical endpoint widely used to measure meaningful visual function improvement in ophthalmology studies. Patients enrolled in the trial will also be followed for 12 months to evaluate long-term safety and tolerability.
Privosegtor is a novel peptoid small molecule engineered to cross both the blood-brain barrier and retinal barrier, targeting neuroprotection directly at the optic nerve and retinal level. Oculis believes the therapy may have broad applications beyond optic neuritis, potentially extending into additional neuro-ophthalmic and neurological diseases where nerve protection remains a major unmet need.
Phase 2 ACUITY Data Demonstrated Strong Neuroprotective Potential
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The Phase 3 PIONEER program follows encouraging results from the completed Phase 2 ACUITY trial, where Privosegtor combined with steroids demonstrated substantial improvements in vision compared with placebo plus steroids. According to the company, patients receiving Privosegtor achieved meaningful gains in low-contrast visual acuity by Month 3, with improvements persisting through Month 6. Investigators also reported positive anatomical and biological indicators of neuroprotection, suggesting preservation of optic nerve structure and function.
Safety findings from the ACUITY study were also favorable. The most commonly reported drug-related adverse events included headache and acne, each occurring in approximately 10.5% of participants. Importantly, no serious drug-related adverse events or treatment discontinuations were reported during the study. These results contributed to Privosegtor receiving both FDA Breakthrough Therapy Designation and the European Medicines Agency’s PRIME designation, highlighting the therapy’s potential importance in addressing a significant unmet medical need.
Potential First Neuroprotective Therapy in Optic Neuritis
Optic neuritis remains a major cause of acute visual impairment, particularly among patients with autoimmune neurological diseases such as multiple sclerosis. Existing treatment approaches primarily focus on reducing inflammation but offer limited ability to directly protect optic nerve cells from irreversible damage. Oculis believes Privosegtor could fundamentally change the treatment landscape by targeting neuroprotection, potentially preserving vision and reducing long-term disability.
Company leadership highlighted the commercial and clinical significance of the opportunity. Oculis estimates the U.S. market for acute optic neuropathies could exceed $7 billion, reflecting the substantial unmet need across neuro-ophthalmology and neurology. Experts involved in the development program noted that the consistency of functional, anatomical, and biological outcomes observed in clinical studies reinforces confidence in Privosegtor’s therapeutic potential.
Oculis Expands Leadership in Neuro-Ophthalmology Innovation
The advancement of Privosegtor further strengthens Oculis’ position as a biotechnology company focused on innovative ophthalmology and neuro-ophthalmology therapies. By securing FDA alignment through the SPA process, the company reduces regulatory uncertainty while accelerating late-stage clinical development. The PIONEER program now represents one of the most advanced neuroprotective development efforts targeting optic neuritis and related neurodegenerative eye disorders.
Source: Oculis Holding AG press release
