Natalizumab

Privosegtor reduced post-onset increases in plasma neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) compared with placebo Lower NfL and GFAP levels provide objective, complementary biological evidence of reduced neuroaxonal injury and suppressed reactive astrogliosis Biomarker results support previously reported functional (LCVA) +18-letter gains and structural retinal preservation at Month 3, reinforcing Privosegtor’s development for acute optic neuritis and acute multiple sclerosis relapses ZUG, Switzerland — October 22, 2026 — Oculis Holding AG (Nasdaq: OCS / XICE: OCS), a global biopharmaceutical company focused on breakthrough innovations to address significant unmet medical needs in neuro-ophthalmology and ophthalmology, today announced new translational biomarker data from the Phase 2 ACUITY trial of Privosegtor in patients with optic neuritis (ON). Increases in plasma neurofilament light chain (NfL) and plasma glial fibrillary acidic protein (GFAP) levels were reduced with Privosegtor vs placebo, particularly at early timepoints close to acute ON onset. Together with previously observed improvements in low-contrast visual acuity with 18-letter gains at Month 3 vs steroid alone, and preserved retinal structure, these findings provide convergent evidence across visual functional, retinal, and serum-based markers, further supporting the evaluation of Privosegtor as a potential neuroprotective therapy. The late-breaking data were presented by Céline Louapre, M.D., Ph.D., of Pitié-Salpêtrière Hospital and Sorbonne University, during the 10th Joint ACTRIMS-ECTRIMS Meeting, MSToronto 2026. The Phase 2 ACUITY biomarker analysis evaluated neurodegenerative markers in the blood to quantify structural neuroaxonal preservation and glial modulation following an acute episode of ON: Neuroaxonal Preservation (LS mean change from baseline in plasma NfL levels, This is demonstrated graphically in a figure in the attached PDF version of this press release. At Day 5, the mean increase in plasma NfL was higher in the placebo group than in the Privosegtor group. NfL levels remained stable in the Privosegtor group through Month 6, whereas levels in the placebo group remained elevated above baseline at Month 1 before returning to baseline by Month 6. Lower NfL levels are consistent with reduced structural neuroaxonal injury along the optic nerve pathway. Reactive Astrogliosis Reduction (LS mean change from baseline in plasma GFAP levels) This is demonstrated graphically in a figure in the attached PDF version of this press release. At Day 5, the mean increase in plasma GFAP was greater in the placebo group than in the Privosegtor group. GFAP levels remained elevated above baseline in the placebo group from Month 1 through Month 6, whereas they remained below baseline in the Privosegtor group over the same period. Lower plasma GFAP levels are consistent with reduced acute reactive astrocytic inflammation and reduction of the secondary neurodegenerative cascade. Céline Louapre, M.D., Ph.D., Professor of Neurology at Pitié-Salpêtrière Hospital, Sorbonne University, and presenting author said: “These findings are particularly noteworthy because they provide biological evidence that complements the functional and retinal structural improvements previously observed in ACUITY. The consistent effects across NfL and GFAP suggest that Privosegtor may be influencing multiple pathways involved in tissue injury following acute optic neuritis, supporting its potential as a neuroprotective therapeutic approach. Together, these data deepen our understanding of the treatment's effects and further support continued clinical evaluation.” Riad Sherif, M.D., Chief Executive Officer of Oculis added: “For patients with optic neuritis, irreversible neuro-axonal damage can occur within days of disease onset, yet there are currently no approved therapies designed to protect retinal ganglion cells and their axons, the neurons responsible for transmitting visual signals from the eye to the brain, and preserve long-term visual function. These biomarker findings and translational analyses provide important additional evidence supporting Privosegtor’s neuroprotective potential, strengthening our confidence as we advance the PIONEER registrational program and explore its broader applicability across acute neuro-axonal conditions, including acute multiple sclerosis relapses.” This Late-Breaker Abstracts poster presentation will be available under the Investors & Media section of the Oculis corporate website at . - Ends - About Privosegtor Privosegtor, a novel peptoid small-molecule candidate that crosses the blood-brain and retinal barriers, has the potential to become the first neuroprotective therapy for optic neuritis (ON) and other neuro-ophthalmic and neuro-axonal diseases. Positive results from the ACUITY Phase 2 trial showed Privosegtor’s neuroprotective potential, as evidenced by improved visual function, corroborated by anatomical preservation of the retina, including the GCIPL and RNFL layers, and reduced neurofilament levels in the blood after an acute episode of optic neuritis. Consistent results were observed in animal models of glaucoma, optic neuritis, and multiple sclerosis (MS), where Privosegtor preserved retinal ganglion cells and was associated with improvements in mobility (clinical function disability) in the MS model. Privosegtor has received Breakthrough Therapy designation from the U.S. Food and Drug Administration (FDA) and Priority Medicines (PRIME) designation from the European Medicines Agency (EMA) as well as Orphan Drug designation from both the FDA and the EMA for ON. Privosegtor is currently being evaluated in Oculis’ PIONEER (Privosegtor Investigation in Optic Neuropathies Efficacy Evaluation Research) program, which includes two registrational trials in ON and one registrational trial in non-arteritic anterior ischemic optic neuropathy (NAION). Building on the ACUITY Phase 2 dataset in ON and constructive FDA pre-IND feedback, Oculis is also planning an IND submission for Privosegtor for the treatment of acute MS relapses. Privosegtor is an investigational drug and has not received regulatory approval for commercial use in any country. About Optic Neuritis Optic Neuritis (ON) is a rare condition characterized by an acute inflammation of the optic nerve that can lead to permanent visual impairment. It affects up to 8 in 100,000 people worldwide with a U.S. annual incidence estimated to be >30,000 and often represents the first sign of multiple sclerosis 1,2 . It mainly occurs in adults between 20 and 40 years of age and is more frequent in women (2:1) 3 . ON is a type of neuropathy (nerve disease) that happens when acute inflammation of the optic nerve affects the signals traveling from the eyes through the brain, causing pain, vision loss and other symptoms. The cells that make up the optic nerve have a lipid protective coating called a myelin sheath, which is preferentially damaged in ON. Without myelin, the optic nerve cells can’t send signals properly and axons can be irreversibly lost. To date there is no specific therapy approved for acute optic neuritis and the unmet need remains for therapies that can prevent vision loss after an acute episode by reducing permanent nerve cell damage or death. About Acute Multiple Sclerosis (MS) Relapses MS is a chronic immune-mediated disease affecting approximately 2.8 million people worldwide, including around 850,000 in the U.S. alone. 4-6 There are two main types of MS: relapsing-remitting MS (RRMS) and progressive MS. While progressive MS remains a significant unmet medical need, RRMS is the most common type, representing ~85% of patients at initial diagnosis. 5 It is currently managed using immunomodulators or disease-modifying therapies (DMTs) that reduce the rate of relapses and therefore related relapse-associated worsening (RAW). However, relapses still persist for many patients, with an estimated 170,000 MS relapses occurring each year in the U.S. 7 During an acute relapse, neurologists commonly use a short course of high-dose corticosteroids to reduce inflammation and shorten the episode, as is also standard of care in optic neuritis. However, corticosteroids do not influence the long-term disability, and recovery from relapses is often incomplete, such as in optic neuritis. The tissue damage that occurs during these relapses can contribute to neuroaxonal loss and the accumulation of functional disability over time, underscoring the need for therapies that protect neurons and axons during relapses. There are currently no neuroprotective therapies approved for MS relapses, and there remains an urgent unmet medical need for treatments that can prevent central nervous system damage. About Oculis Oculis is a global biopharmaceutical company (Nasdaq: OCS; XICE: OCS) focused on breakthrough innovations to address significant unmet medical needs in neuro-ophthalmology. Oculis’ highly differentiated late-stage clinical pipeline focuses on two core product candidates. Privosegtor is a breakthrough neuroprotective candidate in the PIONEER program, which consists of studies intended to support registration plans for treatment of optic neuropathies, including optic neuritis (ON) and non-arteritic anterior ischemic optic neuropathy (NAION). Privosegtor also has potential to be developed for additional indications in other neuro-ophthalmic and neuro-axonal diseases. Licaminlimab is a novel, topical anti-TNFα in a registrational trial, and is being developed with a genotype-based approach for treating patients with TNFR1-mediated dry eye disease (DED). Headquartered in Switzerland with operations in the U.S., Iceland and Switzerland, Oculis is led by an experienced management team with a successful track record and supported by leading international healthcare investors. For more information, please visit: Oculis Contact Ms. Sylvia Cheung, CFO sylvia.cheung@oculis.com Investor Relations LifeSci Advisors Corey Davis, Ph.D. cdavis@lifesciadvisors.com Media Relations ICR Healthcare Amber Fennell oculis@icrhealthcare.com Cautionary Statement Regarding Forward Looking Statements This press release contains forward-looking statements and information. For example, statements regarding the potential benefits of the Company’s product candidates, including the potential for Privosegtor to become the first neuroprotective therapy for optic neuritis and its potential broad applicability across neurology, including in acute MS relapses; the potential significance of biomarker data and analyses; the initiation, enrollment, timing, progress and results of current and future clinical trials; Oculis’ research and development programs; regulatory and business strategy; Oculis’ future development plans; the timing or likelihood of regulatory filings and approvals; and statements about market opportunity, are forward-looking. All forward-looking statements are based on estimates and assumptions that, while considered reasonable by Oculis and its management, are inherently uncertain and are inherently subject to risks, variability, and contingencies, many of which are beyond Oculis’ control. These forward-looking statements are provided for illustrative purposes only and are not intended to serve as, and must not be relied on by an investor as, a guarantee, assurance, prediction or definitive statement of a fact or probability. Actual events and circumstances are difficult or impossible to predict and will differ from assumptions. Results of earlier stage clinical trials may not be replicated in subsequent clinical trials. Statements regarding the potential significance of biomarker data are inherently uncertain, and observed biomarker changes may not be predictive of or correlate with favorable clinical outcomes. All forward-looking statements are subject to risks, uncertainties and other factors that may cause actual results to differ materially from those that we expected and/or those expressed or implied by such forward-looking statements. Forward-looking statements are subject to numerous conditions, many of which are beyond the control of Oculis, including those set forth in the Risk Factors section of Oculis’ annual report on Form 20-F and any other documents filed with the U.S. Securities and Exchange Commission (SEC). Copies of these documents are available on the SEC’s website, Oculis undertakes no obligation to update these statements for revisions or changes after the date of this release, except as required by law. References: Weidong Gu et al. Incidence of Optic Neuritis and the Associated Risk of Multiple Sclerosis for Service Members of U.S. Armed Forces, Military Medicine, vol. 188, March/April 2023 Abbass, N.J., Shaia, J.K., Shukla, P. et al. Prevalence of pediatric and adult optic neuritis in the United States from 2016 to 2023. Eye 39, 1608–1614 (2025). Guier CP, Kaur K, Stokkermans TJ. Optic Neuritis. January 2025 MS National Society Wallin et al., 2019, The prevalence of MS in the United States: A population-based estimate using health claims data - PubMed McGinley et al., 2021, Diagnosis and Treatment of Multiple Sclerosis: A Review - PubMed Multiple sources on relapse rate (ARR) including: Ocrelizumab versus fingolimod after natalizumab cessation in multiple sclerosis: an observational study - PubMed Attachment Oculis Holding AG - Press Release