Claris Biotherapeutics Releases Positive CSB-001 Clinical Proof-of-Concept Data in Limbal Stem Cell Deficiency at AAO 2026 Annual Meeting

– 41% of CSB-001 treated eyes gained ≥15 letters compared to 0% in the non-treatment arm

– 55% of CSB-001 treated eyes gained ≥10 letters compared to 5% in the non-treatment arm

– Responses were durable, with 50% and 81% of treated eyes maintaining ≥15 and ≥10 letter Week 20 improvements, respectively, for 16 weeks post-treatment

– Pivotal studies for CSB-001 in LSCD planned for 1H 2027

San Francisco, Oct. 11, 2026 – Claris Biotherapeutics, Inc., a late-stage biopharmaceutical company dedicated to advancing transformative therapies for sight-threatening conditions where limited or no treatment options exist, today announced positive data from an open-label proof-of-concept study (NCT06452316) evaluating CSB-001 (oremepermin alfa ophthalmic solution) in patients with limbal stem cell deficiency (LSCD), a rare, sight-threatening disease where no approved drug therapy exists. The data were shared in an oral presentation today at the American Academy of Ophthalmology (AAO) 2026 Annual Meeting, held October 9-12, 2026, in New Orleans, LA, by John Affeldt, MD, a study investigator.  

The analysis followed 49 LSCD eyes from 39 subjects with central corneal conjunctivalization and best-corrected visual acuity (BCVA) of ≤65 letters for 20 weeks. Twenty-nine eyes from 23 subjects received topical CSB-001 four times daily for two 8-week treatment periods separated by a one-month dosing holiday; 20 eyes from 16 subjects served as untreated controls. The primary endpoint was change in BCVA at Week 20.

“What is particularly compelling about these data is not only the magnitude of the visual acuity improvements observed, but their persistence beyond the end of treatment,” said John Affeldt, MD, Loma Linda University Medical Center. “For patients with limbal stem cell deficiency, this kind of vision improvement can meaningfully improve daily life. I believe these data represent an important clinical signal as CSB-001 moves to pivotal development.”

Stephen Brady, President and CEO of Claris, added, “Behind every letter of visual acuity gained is a patient regaining independence. People with LSCD have no approved pharmacologic treatment options and live with the risk of blindness. We're excited to report that most treated eyes in this study gained vision — gains that both correlated with anatomical improvements and were, on average, still rising when treatment stopped at Week 20. Claris has an experienced team in place and the financial support to run the planned pivotal studies that we believe give CSB-001 the opportunity to show its full potential, and we look forward to starting those studies in 2027.”

Key highlights from the oral presentation include:

  • At Week 20
    • 41.4% of CSB-001-treated eyes gained ≥15 letters
    • 55.2% of CSB-001-treated eyes gained ≥10 letters from baseline
    • 76% of CSB-001-treated eyes gained any letters
    • 0% gained ≥15 letters and 5% gained ≥10 letters in the untreated eyes 
  • 50% and 81% of treated eyes maintained ≥15 and ≥10 letter Week 20 improvements, respectively, for 16 weeks post-treatment
  • Anatomic changes correlate strongly with functional improvements
  • CSB-001 was assessed as generally safe and well-tolerated

About LSCD and CSB-001

Limbal stem cell deficiency (LSCD) is a disease of the ocular surface in which specialized epithelial stem cells that continuously replenish and repair the corneal surface are dysfunctional or deficient in number, leading to severe vision loss or blindness. There are no pharmacological options approved for the treatment of LSCD. CSB-001 (oremepermin alfa ophthalmic solution) contains recombinant human deleted hepatocyte growth factor (dHGF) as its active ingredient. By promoting corneal epithelial regeneration while modulating inflammation, inhibiting fibrosis and promoting cell survival, CSB-001 has the potential to address the underlying pathophysiology of LSCD. Clinical data demonstrate substantial improvements in visual acuity in LSCD patients treated with CSB-001. 

In 1H 2027, Claris plans to initiate two pivotal studies evaluating the safety and efficacy of CSB-001 compared to vehicle in a total of approximately 400 LSCD subjects. The primary efficacy endpoint will be visual acuity supported by anatomical endpoints. Unlike the proof of concept study that contained a dosing holiday, the planned pivotal studies will dose continuously. If approved, CSB-001 has the potential to become the first pharmacologic treatment for LSCD, providing an efficacious, safe, accessible, and scalable non-surgical treatment option. 

Estimates indicate that at least 30,000 LSCD patients in the U.S. are actively being managed by an eye care professional, with at least 40% of the patients having bilateral disease, although the true prevalence is likely higher due to incomplete disease recognition and underdiagnosis.

About Claris Bio

Claris Biotherapeutics is a late-stage biopharmaceutical company dedicated to advancing transformative therapies for sight-threatening conditions where no or limited treatment options exist. With an initial focus on limbal stem cell deficiency (LSCD), a blinding disease, we are developing the first pharmacologic treatment with the potential to provide a reliable, accessible, and scalable non-surgical treatment option, while moving medical management beyond today's palliative care and towards meaningful improvements in vision and ocular surface health. Our near-term plan is to advance our lead therapeutic candidate, CSB-001 (oremepermin alfa ophthalmic solution), into LSCD pivotal studies in the first half of 2027, with a longer-term goal to become a leader in developing new therapies that improve vision and change patients’ lives. Foundational intellectual property for Claris was based on the scientific work of Drs. Reza Dana, MD, MSc, MPH, and Sunil Chauhan, DVM, PhD., both from the Massachusetts Eye and Ear and the Harvard Medical School Department of Ophthalmology. To learn more, visit www.clarisbio.com.

Media Contact

Jordyn Temperato
LifeSci Communications
jtemperato@lifescicomms.com 

All Press Releases