Claris Bio raises $118m Series B to fund pivotal LSCD eye-drop study
Claris Biotherapeutics has closed a $118 million Series B financing and appointed a new chief executive, chief commercial officer and board chairman as it prepares to move its lead ophthalmic candidate, CSB-001, into pivotal development for limbal stem cell deficiency (LSCD).
The round was co-led by new investors Samsara Biocapital and Catalio Capital Management, joined by Adage Capital Management, Sofinnova Investments, Aisling Capital and ADAR1 Capital Management. Existing investors Novo Holdings, Janus Henderson Investors and Mass General Brigham Ventures all continued their support. The company said proceeds will fund ongoing proof-of-concept and natural history studies, the planned pivotal programme, and early pre-commercialisation activities.
The science and the unmet need
CSB-001, known generically as oremepermin alfa ophthalmic solution, contains recombinant human deleted hepatocyte growth factor as its active ingredient. It is designed to promote corneal epithelial regeneration while suppressing inflammation and fibrosis, addressing what the company describes as the underlying pathophysiology of LSCD. The disease occurs when specialised limbal stem cells that continuously renew the cornea are damaged or destroyed, leading to progressive vision loss and, in severe cases, blindness. No approved pharmacological therapy currently exists for LSCD; management has historically relied on palliative care and, in some cases, surgical stem cell transplantation.
Claris estimates that at least 30,000 LSCD patients in the United States are actively managed by eye care professionals, though it notes that under-diagnosis likely means the true prevalence is higher. Proof-of-concept data generated to date showed what the company characterises as substantial improvements in visual acuity; full results from the open-label 63-patient proof-of-concept study are expected in the second half of 2026. Two pivotal studies enrolling approximately 400 subjects in total are planned to start in the first half of 2027, with visual acuity as the primary endpoint and anatomical measures as supporting endpoints.
Leadership and competitive context
Stephen Brady joins as President and Chief Executive Officer, bringing executive roles at Tempest Therapeutics, Immune Design and Proteolix to his credentials. At Proteolix he led business development that led to the company's sale to Onyx Pharmaceuticals, whose lead asset carfilzomib subsequently drove Amgen's $10.4 billion acquisition of Onyx. Brian Baum steps in as Chief Commercial Officer; he previously led commercial efforts at Dompé Pharmaceuticals for Oxervate, a recombinant nerve growth factor approved for neurotrophic keratitis, a comparably rare and serious ocular surface disease that reached more than $1.1 billion in annual US sales in 2024. Marc de Garidel, currently also CEO of Abivax, joins as Chairman.
The appointment of Baum carries particular strategic weight. Oxervate's commercial trajectory in neurotrophic keratitis offers what is perhaps the closest market analogue for CSB-001: a recombinant protein delivered as an eye drop for a rare, previously untreatable corneal surface disease. That precedent will inform pricing and market access discussions with payers, though LSCD's patient population and competitive dynamics differ and will need their own characterisation.
More broadly, the ophthalmic biologics space is seeing renewed investor interest following a period in which retinal gene therapy dominated deal flow. A number of companies are pursuing cell-based and protein-based approaches to corneal disease, though the LSCD field remains relatively early-stage and Claris appears to hold a clinical lead. Regulatory read-across from neurotrophic keratitis approvals in both the United States and Europe suggests a plausible approval pathway, though the FDA will set its own bar for the pivotal programme design.
With the company stating it is financed through Phase 3 and pre-commercialisation work already under way, the critical near-term milestones are the proof-of-concept data readout later in 2026 and confirmation of pivotal study design parameters.