Oculis Holding has announced a major regulatory milestone -- its neuroprotective candidate Privosegtor has been granted Breakthrough Therapy Designation by the US FDA for the treatment of optic neuritis (ON).

 

Privosegtor, a novel peptoid small molecule designed to cross both the blood–brain and retinal barriers, could become the first neuroprotective therapy for optic neuropathies, conditions that can lead to permanent vision loss due to nerve cell damage. With no current neuroprotective treatments available, the US market for these diseases alone is estimated at $7 billion.

 

The FDA designation follows visual-function results from the Phase 2 ACUITY trial, which evaluated Privosegtor in optic neuritis—a rare, sight-threatening condition often serving as the first sign of multiple sclerosis. In the trial, Privosegtor demonstrated substantial improvements in low-contrast visual acuity (LCVA) along with consistent anatomical and biological benefits compared with placebo.

 

Patients receiving Privosegtor 3 mg/kg/day plus IV methylprednisolone gained an average of 18 letters at three months on the 2.5% ETDRS Low Contrast Letter Acuity chart, compared with placebo. 

 

A 15-letter gain—roughly three lines on the chart—is considered clinically meaningful for daily visual function. Privosegtor also preserved retinal and optic nerve structure, and additional analyses showed reduced neurofilament release, a biomarker of decreased nerve injury. The most common drug-related side effects were headache and acne (each in two participants, 10.5%). No serious drug-related adverse events were reported.

 

Following a successful FDA meeting in 2025, Oculis launched the PIONEER program, comprising three pivotal trials to support registration plans for Privosegtor in ON and a second rare neuro-ophthalmic disease, NAION. The first trial, PIONEER-1 in ON, began in Q4 2025 and spans three continents, with enrollment set to start shortly.

 

Riad Sherif, CEO of Oculis, said: "Today’s Breakthrough Therapy Designation underscores Privosegtor’s significant potential as a first‑of‑its‑kind neuroprotective therapy for people living with optic neuritis, and highlights our commitment to redefining what’s possible for patients suffering from neuroaxonal loss. 

 

"With the ACUITY results and Privosegtor now progressing as a neuroprotective platform across key neuro‑ophthalmic diseases, Oculis is uniquely positioned to reshape the treatment landscape in areas with substantial unmet needs, and 2026 is shaping up to be a milestone‑rich year across our late‑stage portfolio.”

 

Mark Kupersmith, Chief Medical Advisor, Neuro-Ophthalmology, added: "The ACUITY trial delivered truly groundbreaking results, demonstrating for the first time in a single study that a drug candidate consistently improves visual function alongside anatomical and biological evidence of neuroprotective benefit. 

 

"Significant unmet medical needs remain, as patients with optic neuritis—more often young women and frequently experiencing the first sign of multiple sclerosis—are still at high risk of permanent visual loss.”