SAN FRANCISCO, Calif. — October 11, 2026
Claris Biotherapeutics, Inc. announced positive proof-of-concept results for CSB-001 (oremepermin alfa ophthalmic solution) in patients with limbal stem cell deficiency (LSCD), a rare, sight-threatening eye disease that can cause severe visual impairment or blindness. The findings were presented in an oral presentation at the American Academy of Ophthalmology (AAO) 2026 Annual Meeting in New Orleans, Louisiana. In the open-label study, 41.4% of CSB-001-treated eyes gained at least 15 letters in best-corrected visual acuity at Week 20, compared with none in the untreated control group. Additionally, 55.2% of treated eyes gained at least 10 letters, compared with 5% of untreated eyes. Improvements were reported to persist after treatment ended, with 50% of treated eyes maintaining gains of at least 15 letters and 81% maintaining gains of at least 10 letters for 16 weeks after Week 20. The company also reported that visual improvements correlated with anatomical changes and that CSB-001 was generally safe and well tolerated. Claris plans to initiate two pivotal studies in the first half of 2027, further evaluating the investigational therapy as a potential pharmacological treatment for LSCD, for which no drug therapy is currently approved.
CSB-001 Shows Visual Acuity Improvements in LSCD
The proof-of-concept study (NCT06452316) evaluated 49 eyes from 39 participants with central corneal conjunctivalization and baseline best-corrected visual acuity of 65 letters or fewer. Of these, 29 eyes from 23 participants received topical CSB-001 four times daily during two eight-week treatment periods separated by a one-month dosing holiday, while 20 eyes from 16 participants served as untreated controls. The primary endpoint was change in visual acuity at Week 20. At that time point, 41.4% of treated eyes gained 15 or more letters, while 55.2% gained at least 10 letters and 76% gained some letters from baseline. In comparison, no untreated eyes gained at least 15 letters, and 5% gained at least 10 letters. These results indicate a potentially meaningful visual acuity signal in a patient population with limited treatment options. However, the study was open-label and included a relatively small number of eyes, so the findings require confirmation in larger, controlled pivotal trials. The reported comparisons should also be interpreted in light of the study design and the possibility that outcomes may differ in a larger patient population.
Visual Improvements Persist After Treatment Ends
Claris reported that visual acuity gains observed during treatment were maintained in many treated eyes during the post-treatment follow-up period. Fifty percent of treated eyes maintained improvements of at least 15 letters, while 81% maintained gains of at least 10 letters for 16 weeks after the Week 20 assessment. The company also reported a strong correlation between anatomical improvements and functional visual gains, suggesting that changes in the corneal surface may be associated with improved vision. According to study investigator John Affeldt, M.D., the persistence of visual improvements beyond the treatment period is an important finding for people living with LSCD. The disease affects limbal stem cells that normally replenish and repair the corneal epithelium, potentially resulting in an unstable ocular surface, corneal damage and substantial vision loss. Although the durability findings are encouraging, they come from an early proof-of-concept study and do not establish how long benefits may persist in a broader population or with different treatment schedules. Further clinical research will be needed to characterize long-term outcomes and determine whether the observed benefits can be reproduced under controlled conditions.
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Claris Plans Pivotal CSB-001 Studies for 2027
CSB-001 contains recombinant human deleted hepatocyte growth factor (dHGF) as its active ingredient and is designed to promote corneal epithelial regeneration while modulating inflammation, inhibiting fibrosis and supporting cell survival. The candidate is being developed as a potential nonsurgical treatment addressing aspects of LSCD biology. Claris plans to begin two pivotal studies in the first half of 2027, evaluating CSB-001 against vehicle in approximately 400 participants in total. Visual acuity is expected to serve as the primary efficacy endpoint, supported by anatomical assessments. Unlike the proof-of-concept study, which included a dosing holiday, the planned pivotal studies are expected to use continuous dosing. The company described CSB-001 as generally safe and well tolerated in the proof-of-concept study, although more extensive data will be needed to establish its safety profile. Claris estimates that at least 30,000 LSCD patients in the United States are actively managed by eye-care professionals, with a substantial proportion affected in both eyes. If pivotal trials demonstrate sufficient safety and efficacy and the candidate receives regulatory approval, CSB-001 could potentially become a first pharmacological treatment option for LSCD. The planned studies will be important in determining whether the preliminary visual acuity and durability findings translate into reproducible clinical benefits.
Source::Claris Biotherapeutics press release
