Claris Biotherapeutics announced positive data from an open-label proof-of-concept study evaluating CSB-001 (oremeperminalfaophthalmic solution) in patients with limbal stem cell deficiency (LSCD). The data were shared in an oral presentation at the American Academy of Ophthalmology 2026 annual meeting 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 4 times daily for 2, 8-week treatment periods separated by a 1-month dosing holiday; 20 eyes from 16 subjects served as untreated controls. The primary endpoint was change in BCVA at Week 20.

Among the key highlights from the oral presentation, 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, and 0% gained ≥15 letters and 5% gained ≥10 letters in the untreated eyes. 

In addition, 50% and 81% of treated eyes maintained ≥15 and ≥10 letter Week 20 improvements, respectively, for 16 weeks posttreatment; anatomic changes correlate strongly with functional improvements, and CSB-001 was assessed as generally safe and well-tolerated. 

In 1H 2027, Claris said it plans to initiate 2 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, the company said.