Therini Bio Initiates Phase 1b Trial of Novel Anti-Inflammatory Therapy THN391 for Diabetic Macular Edema
Key Insights
Therini Bio (search) has dosed the first patients in a Phase 1b trial evaluating THN391, a potential first-in-class humanized monoclonal antibody targeting fibrin-driven inflammation in diabetic macular edema (search).
THN391 demonstrated efficacy comparable to VEGF (search) antagonists in preclinical models for containing neovascular leakage, according to research published in the Journal of Neuroinflammation.
The company is also advancing THN622 (search), a bispecific antibody combining anti-fibrin and anti-VEGF (search) mechanisms that could potentially become a new standard of care for neurodegenerative ocular diseases.
Therini Bio (search) has achieved a significant clinical milestone by dosing the first patients in a Phase 1b trial of THN391, a novel anti-inflammatory therapy for diabetic macular edema (search) (DME (search)). The Sacramento-based clinical-stage biotech company announced the initiation of this multiple ascending dose study on May 27, 2026, marking an important step forward in addressing vascular-mediated inflammation in neurodegenerative eye diseases.
Novel Mechanism Targets Fibrin-Driven Inflammation
THN391 represents a potential first-in-class approach to treating DME (search) by targeting fibrin's inflammatory epitope. In DME, loss of vascular integrity leads to the accumulation of toxic fibrin deposits and induces chronic neuroinflammation, resulting in neuro-retinal degeneration. The high-affinity, humanized monoclonal antibody is designed to selectively block fibrin's inflammatory epitope and halt the neuroinflammation cascade without disrupting coagulation.
Preclinical validation for THN391's approach comes from recently published research in the Journal of Neuroinflammation (Kantor et al., 2026), where Therini demonstrated that THN391 was as effective as VEGF (search) antagonists in containing leakage from neovascular lesions in preclinical models.
Phase 1b Trial Design and Endpoints
The ongoing Phase 1b study will assess both safety and preliminary efficacy of THN391 in patients with DME (search). The trial is designed to include three dose cohorts, with each patient receiving three monthly intravitreal injections. Beyond safety evaluation, biological activity will be measured using retinal central subfield thickness, visual acuity, and exploratory biomarkers. Initial data is expected in Q4 2026.
"The dosing of the first cohort of patients in our THN391 trial represents a significant milestone for Therini Bio (search)," said Joel Naor, M.D., M.B.A., MSc., Chief Medical Officer – Ophthalmology of Therini Bio. "By targeting fibrin-driven inflammation, THN391 has the potential to enhance retinal health, improve treatment outcomes, and preserve vision in patients with DME (search)."
Pipeline Advancement with Bispecific Approach
Therini Bio (search) has also selected THN622 (search) as its lead candidate for further development. THN622 is a bispecific anti-fibrin inflammatory epitope and anti-VEGF (search) blocking antibody designed to treat retinal conditions characterized by vascular dysfunction, including DME (search). The dual mechanism of action combines the current standard of care, responsible for treating VEGF-mediated leakage, with a novel fibrin blocker intended to prevent the underlying neuroinflammation.
According to the company, the combination of these two mechanisms may potentially increase treatment efficacy, increase overall response rates, increase durability, prevent fibrosis and emerge as the new standard for the treatment of neurodegenerative ocular diseases.
Company Background and Investment
Therini Bio (search) focuses on developing immunotherapies for vascular-mediated inflammation with particular emphasis on neuroinflammation in diseases driven by vascular dysfunction. The company's pipeline includes potential first-in-class therapies selectively targeting fibrin-mediated inflammation for diseases including Alzheimer's disease (search) and diabetic macular edema (search), where vascular-mediated inflammation plays a central role in the disease process.
The company has attracted investment from a top-tier syndicate of life sciences investors including the Alzheimer's Drug Discovery Foundation, Angelini Ventures, Apollo Health Ventures, SV Health Investors' Biotech Fund and Dementia Discovery Fund, Dolby Family Ventures, Dreavent Biotech Investments, Eli Lilly and Company, Foundation for a Better World, Mitsui Global Investment, MRL Ventures Fund (the therapeutics-focused corporate venture fund of Merck & Co., Inc.), and Sanofi Ventures (search).