Claris Bio reports positive CSB-001 data in rare corneal disease

Claris Biotherapeutics has presented clinical proof-of-concept data for CSB-001 (oremepermin alfa ophthalmic solution) in limbal stem cell deficiency, a rare sight-threatening disease for which no approved pharmacological treatment currently exists. The data were delivered in an oral presentation at the American Academy of Ophthalmology Annual Meeting in New Orleans on 11 October 2026.

The open-label study (NCT06452316) followed 49 eyes from 39 subjects over 20 weeks. Twenty-nine eyes from 23 subjects received topical CSB-001 four times daily across two eight-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 best-corrected visual acuity at Week 20.

Clinical results

At Week 20, 41% of CSB-001-treated eyes gained at least 15 letters of visual acuity, compared with 0% in the untreated control arm. Some 55% of treated eyes gained at least 10 letters, versus 5% in controls, and 76% of treated eyes gained any letters from baseline. The company also reported durable responses: 50% of treated eyes maintained a gain of at least 15 letters, and 81% maintained at least 10 letters, for 16 weeks after treatment ended.

Anatomical improvements were said to correlate strongly with functional gains. CSB-001 was assessed as generally safe and well-tolerated, though the release did not provide a detailed adverse-event breakdown.

John Affeldt, MD, of Loma Linda University Medical Center, who presented the data, said the persistence of vision gains beyond the end of treatment was "particularly compelling" and that the results represent "an important clinical signal as CSB-001 moves to pivotal development."

Regulatory path and market context

Claris plans to initiate two pivotal studies in the first half of 2027, enrolling approximately 400 subjects in total, with visual acuity as the primary efficacy endpoint and anatomical measures as secondary support. Unlike the proof-of-concept study, the pivotal programme will dose continuously without a treatment holiday, potentially strengthening the efficacy signal.

LSCD is an unmet-need indication with an estimated 30,000 actively managed patients in the United States. At least 40% are said to have bilateral disease, though the company acknowledges the true prevalence is likely higher owing to underdiagnosis. With no approved pharmacological option, the regulatory bar for benefit-risk assessment is relatively clear, and the FDA has historically been receptive to approving first-in-class therapies in sight-threatening rare diseases.

CSB-001's active ingredient, recombinant human deleted hepatocyte growth factor, is designed to promote corneal epithelial regeneration while modulating inflammation and inhibiting fibrosis. The biologic mechanism distinguishes it from the surgical approaches, including keratolimbal allograft, that currently represent the main interventional options for severe LSCD. Several academic groups and smaller biotechs have explored cell-based and growth-factor approaches to corneal surface repair, but the field has produced few late-stage programmes, leaving the competitive landscape relatively open for a well-resourced pivotal-stage entrant.

Claris said it has the financial resources in place to fund the planned pivotal studies. No partnership or out-licensing arrangement was mentioned, and the company did not disclose a post-money valuation or current cash position.