Claris Reports Sustained Visual Gains With CSB-001 in LSCD Study

Claris Biotherapeutics has reported early clinical findings for CSB-001 (oremepermin alfa ophthalmic solution), an investigational eye drop being developed for limbal stem cell deficiency (LSCD). Results from the proof-of-concept study (NCT06452316), were presented at the American Academy of Ophthalmology (AAO) 2026 Annual Meeting in New Orleans, held from October 9 to 12.

At Week 20, 41.4% of treated eyes had gained at least 15 letters on a visual-acuity assessment, while 55.2% had gained at least 10 letters. The company also reported that some improvements persisted for 16 weeks after treatment stopped.

Although the findings indicate a potential clinical signal, the study was open-label and the reported comparison involved untreated control eyes rather than a vehicle-treated control arm. Further controlled studies will be needed to determine whether the observed improvements can be reproduced and to characterize the treatment’s safety.

Treatment Challenges in Limbal Stem Cell Deficiency

LSCD develops when limbal stem cells, which maintain and regenerate the corneal surface, are damaged or become deficient. The resulting disruption can allow conjunctival tissue to spread across the cornea, compromising its transparency and potentially causing substantial visual impairment.

The condition can follow chemical or thermal injuries and other damage to the ocular surface. Management depends on disease severity and the extent of tissue damage. Some patients receive supportive care, while advanced cases may require surgery. Restoring a stable corneal surface remains challenging for some patients.

According to Claris, no pharmacological treatment is currently approved specifically for LSCD. The company estimates that at least 30,000 patients in the United States are actively managed for the condition, with at least 40% having bilateral disease. These are company-reported estimates, and the actual disease burden may be higher because of underdiagnosis.

Study Design and Primary Endpoint

The open-label proof-of-concept analysis included 49 eyes from 39 participants. Of these, 29 eyes from 23 participants received CSB-001, while 20 eyes from 16 participants served as untreated controls. The treatment schedule consisted of four-times-daily eye drops for eight weeks, followed by a one-month break and a second eight-week treatment period.

The primary endpoint was change in best-corrected visual acuity (BCVA) at Week 20. Researchers also assessed changes in ocular surface anatomy and followed participants after treatment to evaluate the persistence of visual improvements.

Visual-Acuity Improvements at Week 20

At Week 20, 41.4% of CSB-001-treated eyes gained at least 15 letters from baseline, while 55.2% gained at least 10 letters. The company reported some improvement in visual acuity in 76% of treated eyes.

In the untreated control eyes, none gained at least 15 letters, and 5% gained at least 10 letters.

These findings suggest a difference in the proportion of eyes achieving the reported visual-acuity thresholds. However, the study design and limited sample size prevent definitive conclusions about treatment efficacy.

Claris also reported a strong association between changes in ocular surface anatomy and visual function. More detailed data would help establish the extent of this relationship and its clinical significance.

Persistence of Benefit and Safety Findings

The company reported that visual improvements persisted during the 16 weeks following treatment. Among treated eyes, 50% maintained an improvement of at least 15 letters at Week 20, while 81% maintained an improvement of at least 10 letters.

These findings raise the possibility that some visual improvements may persist beyond active dosing. However, the available follow-up does not establish how long the effects might last beyond the observed period or whether additional treatment would be required.

Claris described CSB-001 as generally safe and well tolerated in the study. Its announcement did not provide detailed adverse-event figures, limiting the extent to which the safety profile can be assessed from the reported results.

Pivotal Trials Will Test Reproducibility

CSB-001, also known as oremepermin alfa ophthalmic solution, contains recombinant human deleted hepatocyte growth factor (dHGF). The treatment is being investigated for its potential to support corneal epithelial regeneration while modulating inflammation, fibrosis and cell survival. These proposed biological effects have not yet established the mechanism underlying the reported clinical improvements.

Claris plans to initiate two pivotal studies in the first half of 2027, involving approximately 400 participants in total. The planned studies will compare CSB-001 with vehicle, with visual acuity serving as the primary efficacy endpoint and anatomical assessments providing additional evidence. Unlike the proof-of-concept study, the pivotal studies are expected to use continuous dosing without a treatment holiday.

The pivotal programme will need to establish whether the early visual-acuity findings are reproducible in a controlled setting, while providing a more comprehensive assessment of safety and the durability of benefit with continued treatment.

For now, CSB-001 remains investigational. The proof-of-concept findings provide a basis for further evaluation, but whether the treatment can deliver a consistent clinical benefit in LSCD will depend on the results of the planned pivotal studies.

Reference

Claris Biotherapeutics Releases Positive CSB-001 Clinical Proof-of-Concept Data in Limbal Stem Cell Deficiency at AAO 2026 Annual Meeting, Claris Bio, 11 October 2026

Study to Evaluate the Safety and Efficacy of CSB-001 Ophthalmic Solution 0.1% in Subjects with Limbal Stem Cell Deficiency, ClinicalTrials.gov ID NCT06452316