Oculis Holding AG has received Breakthrough Therapy Designation from the FDA for privosegtor, a neuroprotective candidate under clinical investigation for the treatment of optic neuritis.
So! Where to start?
We’ll begin with privosegtor.
What it is: Initially referred to as OCS-05, this is a novel peptoid small molecule asset that acts as a serum-glucose corticoid kinase-2 (SGK-2) activator to penetrate the blood-brain and retinal barrier.
- Check out its mechanism of action, which involves preserving the retina and improving visual function following an acute episode of ON.
Its potential: To become the first neuroprotective therapeutic for acute ON (AON) and non-arteritic anterior ischemic optic neuropathy (NAION).
Now, before we get into its clinical data, let's talk about this designation.
BTD is intended to expedite the development and review process for drugs designed to treat a serious or life-threatening disease (such as optic neuropathies).
- See here for all criteria a drug must meet to qualify for this designation, including preliminary clinical evidence supporting its use over other available therapies (if applicable).
- And check out the benefits that come with BTD.
Plus: BT-designated drugs are eligible to receive all Fast Track designations offered by the FDA, as well as more (and earlier) guidance on their development programs.
But this isn’t the first designation privosegtor has secured, right?
Correct. The candidate was previously granted Orphan Drug designation from the FDA for its AON indication (as well as by the European Medicines Agency for NAION).
Noted. So what clinical evidence supported privosegtor for BTD?
That would be the phase 2 Acute OptiC NeUrITis of DemYelinating Origin (ACUITY) trial (NCT04762017).
Its purpose: To evaluate a once-daily intravenous (IV) infusion of privosegtor over a 5-day period (versus placebo) among AON patients receiving corticosteroids.
And what to know about its findings?
As Oculis reported in January 2025: The study met its primary safety endpoint as well as showcased privosegtor’s neuroprotective structural benefit and ability to improve visual function among AON patients (secondary efficacy endpoints).
Some numbers:
- Privosegtor produced substantial vision improvements on the 2.5% Early Treatment Diabetic Retinopathy (ETDRS) low-contrast letter acuity (LCVA) chart
- Patients receiving privosegtor plus corticosteroids gained an average of 18 letters at 3 months versus placebo with corticosteroids
Read the full data readout.
Sounds promising … so what are the next steps for this candidate?
Oculis reported in October 2025 that it had met with—and received positive feedback from—the FDA regarding plans to kick off a new clinical program (with three global trials) dubbed PIONEER evaluating privosegtor for both AON and NAION.
And as CEO Riad Sherif, MD, told Glance, the first PIONEER trial was initiated at the end of 2025, with “enrollment anticipated to begin shortly.”
The intent: For these trials to support registration plans for privosegtor in both its proposed indications.
Lastly, what’s the significance of this candidate?
Privosegtor’s advancement in the registrational PIONEER program in optic neuropathies is “only the beginning,” Dr. Sherif told Glance.
“Its neuroprotective potential could reach far beyond to fulfil substantial unmet medical needs in multiple neuro-axonal diseases,” he said.
As always, stay tuned for more clinical developments later this year!
Editor's note: This article was updated on Jan. 7, 2026.