A Simple Eye Drop For A Blinding Disease? Claris Bio Raises $118M And Prepares For Pivotal Trials

By Ray Dogum, Chief Editor, Drug Discovery Online

Key Takeaways

• A topical eye drop of oremepermin alfa ophthalmic solution could address a significant unmet need: Stephen Brady, CEO, Claris Bio, believes CSB-001 has the potential to improve vision and slow vision loss in limbal stem cell deficiency (LSCD) patients using a non-surgical, easily administered treatment approach.
• Claris raised $118 million Series B after observing encouraging, but not yet fully publicly disclosed, proof-of-concept findings with CSB-001 in LSCD.
• Phase 3 preparation is already underway. Claris is leveraging a non-interventional LSCD study to generate natural history data, pre-qualify sites, and identify potential trial participants ahead of pivotal studies planned for next year.

Encouraging Data Illuminates An Underdiagnosed Rare Disease

Claris Bio is preparing to disclose proof-of-concept data for CSB-001 in limbal stem cell deficiency (LSCD), a rare, potentially blinding ocular-surface disorder with no approved pharmaceutical therapy. The company’s recent $118 million Series B financing is intended to carry CSB-001 through development and support early pre-commercialization work, with phase 3 LSCD studies expected to begin in the first half of 2027.

The financing followed encouraging findings from Claris’ ongoing LSCD study, though the company has not yet publicly shared detailed efficacy results. “We haven’t disclosed the specific data yet,” Stephen Brady, CEO, Claris Bio, told Drug Discovery Online. Investors, however, reviewed the underlying data during fundraising. “The data are what catalyzed the round, obviously,” he said.

Brady brings nearly three decades of life sciences leadership experience to Claris, including prior roles as chairman and CEO of Tempest Therapeutics and executive vice president of strategy and finance at Immune Design, where he helped guide the company through its IPO, financings, licensing transactions, and sale to Merck.

Brady estimates that at least 30,000 patients in the U.S. are living with LSCD, a number he believes may be conservative because the disease is often underdiagnosed. Many ophthalmologists know the condition, he said, but may not actively look for it because no drug treatment currently exists. “One of the reasons it's underdiagnosed is there's no therapeutic for it,” Brady explained.

To support patient identification, Claris has begun physician outreach and is developing diagnostic support tools. “We're working on our own software to help diagnose and take photos. More to come on that later.”

How The Eye Drop Is Designed To Regenerate The Cornea

CSB-001 (oremepermin alfa ophthalmic solution) is a recombinant, five-amino-acid-deleted form of hepatocyte growth factor isoform 3 (HGF3). Claris’ therapeutic rationale is to activate c-Met signaling, a pathway involved in epithelial cell migration, proliferation, and wound repair, to help restore the corneal surface.

In LSCD, the limbal stem cell niche is damaged or depleted, leaving the eye unable to properly regenerate the transparent epithelial layer needed for vision.

By stimulating repair signaling at the ocular surface, CSB-001 is intended to promote restoration of the corneal epithelium while potentially modulating inflammation and fibrosis. “The purported mechanism is that this growth factor signals through c-Met,” Brady explained, “and causes the cells to divide and differentiate into the cells that eventually become the epithelium on your cornea.  It's the signaling through that receptor which we think is the key reason the drug appears to be working.”

The Observation That Redirected The Program

Claris Bio was co-founded in 2018 by Reza Dana, M.D., Sunil Chauhan, Ph.D., and biotech executive Clarke Atwell to advance ophthalmic therapies based on hepatocyte growth factor (HGF) research originating at Massachusetts Eye and Ear and Harvard-affiliated laboratories.

The LSCD program grew out of Claris’ earlier work in neurotrophic keratitis (NK). The company’s completed Phase 1/2 NK study did not establish CSB-001 as a therapy for that condition, but Brady said an investigator noticed that a participant who also had LSCD experienced improved vision. “She was the one that broke it all open,” he said. That observation helped redirect the program toward LSCD as the company’s lead indication.

Why Oxervate Offers A Commercial Analog

Brady sees Dompé’s Oxervate, an approved topical ocular therapy for NK in the U.S. since 2018, as a useful proxy for how the LSCD market could develop. In both diseases, specialists may learn about the condition during medical training but had limited incentive to diagnose it early when no drug option exists. Brady said that dynamic has contributed to LSCD being overlooked.

Patients may receive surgical procedures that require long-term recovery and possible immunosuppression. Claris is trying to get ahead of that curve by educating specialists, supporting diagnosis, and preparing the market before Phase 3 begins.

What To Watch Next

Looking ahead, the main value inflection point will be the release of LSCD proof-of-concept results in the fall of 2026, followed by the planned start of pivotal development in the first half of 2027.

Manufacturing readiness, chronic toxicology, diagnostic standardization, and the reproducibility of visual-acuity improvements in controlled pivotal trials will determine whether CSB-001 can move from an intriguing clinical observation to a therapy for a disease that currently has no approved drug option. “This is an eye drop,” Brady said. “We’re improving vision in a significant percentage of these patients, and we’re arresting vision loss with a simple drop.”