Claris Biotherapeutics Raises $118M Series B for CSB-001

Claris Biotherapeutics closed a $118M Series B financing on July 28, 2026, giving the Jersey City, New Jersey-based biotechnology company funding through the Phase 3 evaluation of CSB-001, its lead treatment for limbal stem cell deficiency, or LSCD. Samsara BioCapital and Catalio Capital Management co-led the round, with Adage Capital Management, Sofinnova Investments, Aisling Capital, ADAR1 Capital Management, and returning investor Novo Holdings participating. Combined with the $57M Series A announced in January 2024, Claris Biotherapeutics has raised approximately $175M in disclosed funding.

The number matters. The timing matters more. Claris Biotherapeutics has reported positive proof-of-concept data showing substantial visual acuity improvements in LSCD patients treated with CSB-001 and plans to begin a pivotal Phase 3 program in H1 2027. The Series B is essentially a $118M wager that encouraging clinical evidence can survive the considerably less forgiving world of pivotal development. For biotech investors and operators, that is the real story. Capital is still available when science, unmet medical need, clinical evidence, and a defined development path arrive at the same table. The table just has fewer chairs than it used to.

What Happened

Claris Biotherapeutics raised $118M to complete ongoing LSCD trials and finance the planned Phase 3 evaluation of CSB-001. The financing was co-led by Samsara BioCapital and Catalio Capital Management, bringing disclosed funding at Claris Biotherapeutics to approximately $175M. No Series B post-money valuation has been publicly disclosed.

CSB-001, also known as oremepermin alfa ophthalmic solution, is a topical ocular biologic formulation of recombinant human deleted hepatocyte growth factor, or dHGF. Claris Biotherapeutics is developing the therapy to restore structural and functional corneal integrity in patients with LSCD. Claris management estimates at least 30,000 U.S. patients are currently treated for LSCD and believes true prevalence is higher. The company states that no drug therapy is currently approved for LSCD. The disease is defined, the unmet need is visible, human data have begun establishing the case, and Phase 3 provides the next hard checkpoint. Biotech eventually makes everybody show their work.

Why the $118M Series B Matters

The most important feature of the $118M Series B is runway. Claris Biotherapeutics says the financing carries the company through Phase 3 evaluation of CSB-001, changing the conversation from whether the company can finance pivotal development to what the drug can demonstrate once it gets there. A non-interventional natural history study is underway ahead of the planned pivotal program beginning in H1 2027.

The business lesson is less glamorous than the usual venture mythology, which is precisely why it matters. Claris Biotherapeutics paired differentiated intellectual property with reported human evidence, a disease lacking an approved drug therapy, and identifiable clinical milestones. Investors responded with enough capital to finance the next major test. Capital met evidence. Evidence created conviction. Conviction purchased time. For clinical-stage biotechnology companies operating in a selective funding market, that sequence is worth considerably more than another founder sermon about perseverance.

The Science Behind CSB-001

Claris Biotherapeutics traces its foundational intellectual property to Massachusetts Eye and Ear and research conducted by scientific co-founders Reza Dana, MD, MSc, MPH, FARVO, and Sunil Chauhan, DVM, PhD, involving mesenchymal stem cells and hepatocyte growth factor. The foundational IP was licensed from Massachusetts Eye and Ear Infirmary, while drug substance for the program is sourced through a partnership with Kringle Pharma.

CSB-001 is being developed as a topical treatment for limbal stem cell deficiency, a corneal disorder involving deficient or dysfunctional limbal stem cells needed to maintain and repair the corneal surface. Claris Biotherapeutics designed CSB-001 to restore structural and functional corneal integrity rather than simply manage a symptom downstream. A therapy addressing an identifiable biological mechanism in a disease without an approved drug treatment presents a different proposition from science searching for commercial relevance after the laboratory work is finished. Phase 3 will determine how much of that proposition survives contact with scale.

Investors Are Buying More Than a Clinical Milestone

Samsara BioCapital and Catalio Capital Management did not arrive alone. Adage Capital Management, Sofinnova Investments, Aisling Capital, ADAR1 Capital Management, and Novo Holdings participated in the Series B. The financing represents a mix of new and returning institutional capital positioned around a late-clinical-stage ophthalmology program approaching its pivotal test.

The board creates direct connective tissue between capital and company governance. Michael Dybbs, PhD, Partner at Samsara BioCapital, and Matthew Hobson, PhD, Principal at Catalio Capital Management, serve on the Claris Biotherapeutics board alongside Meredith Fisher, PhD, MBA, Partner at Mass General Brigham Ventures; Kenneth Harrison, PhD, Senior Partner at Novo Ventures; Maha Radhakrishnan, MD, Executive Partner at Sofinnova Investments; Co-Founder Reza Dana; and Chairman Marc de Garidel, MIM, AMP, who is also CEO of Abivax. The institutions providing capital are close to the decisions governing how that capital gets deployed. Sophisticated investors understand that Phase 3 is where elegant scientific narratives acquire expensive opinions from reality.

Claris Biotherapeutics Is Building for Phase 3

Claris Biotherapeutics grew from a founding team of 5 to more than 25 employees by the Series B announcement. CEO Stephen Brady leads the company alongside Co-Founder and COO Clarke Atwell, MIBS. The leadership organization includes Chief Medical Officer Susan Orr, OD; Chief Business Officer Henry Rath; Chief Commercial Officer Brian Baum; Senior Vice President of Clinical Development Tomi Luan, OD, PhD; and Senior Vice President of CMC Piotr Bryla, PhD. Reza Dana remains a Co-Founder and Board Member, while Sunil Chauhan serves as Co-Founder and Scientific Advisor / Board Observer.

Those hires matter because Claris Biotherapeutics is approaching a different species of company-building problem. Early biotechnology can survive around scientific possibility. Late-stage biotechnology needs operations, manufacturing discipline, trial execution, regulatory planning, and commercial thinking to coexist without murdering one another in meetings. Claris is no longer simply building CSB-001. It is building the organization required to carry CSB-001 through its next stage.

What This Signals for Biotech Funding

The Claris Biotherapeutics Series B illustrates a broader reality in biotechnology financing: investors can be selective without being timid. Claris entered the round with reported human proof-of-concept data, a defined lead asset, an identifiable patient population, foundational research from Massachusetts Eye and Ear, and a planned Phase 3 program. The $118M financing provides enough runway to reach a major clinical milestone rather than financing another short sprint toward the next fundraising conversation.

That matters beyond ophthalmology. The lesson is not that every biotechnology company with promising science can raise $118M. Quite the opposite. Large rounds become easier to understand when investors can trace a clean line from mechanism to evidence, evidence to clinical development, and clinical development to a potentially meaningful market. Claris Biotherapeutics has now been given the capital to run that line much farther.

The Bigger Strategic Question

CEO Stephen Brady has indicated that Claris Biotherapeutics could pursue a public listing through an IPO or reverse merger ahead of Phase 3 data rather than target a sale, while leaving open the possibility of pipeline expansion if Claris remains independent and sufficiently capitalized. No public-market transaction has been announced. If CSB-001 continues advancing and public-market conditions cooperate, Claris could eventually approach investors with Phase 3 underway, financing secured through evaluation, and a lead asset targeting a disease the company says has no approved drug therapy.

No Series B post-money valuation has been publicly disclosed, so pretending to know precisely how investors priced that future would be financial fan fiction. What is known is more useful: Claris Biotherapeutics has $118M in new capital, approximately $175M in total disclosed funding, reported positive proof-of-concept data, a Phase 3 program planned for H1 2027, and investors willing to finance the company through that evaluation. The funding announcement is finished. The experiment is getting expensive enough to become interesting.