Key Takeaways

• Therini Bio has dosed the first patients in a phase 1b clinical trial evaluating THN391, a fibrin-targeting monoclonal antibody for the treatment of DME, with initial data expected in 4Q 2026
• THN391 is designed to selectively block fibrin-driven neuroinflammation without affecting normal coagulation, offering a potential new therapeutic approach for retinal diseases associated with vascular dysfunction and neurodegeneration.

Therini Bio announced that the first patients have been dosed in a phase 1b clinical trial evaluating THN391 for the treatment of diabetic macular edema (DME). The company also provided an update on its ophthalmology pipeline, including the selection of THN622, a fibrin/VEGF bispecific antibody candidate, for further development.

Therini’s lead ophthalmology candidate, THN391, is a potential first-in-class, high-affinity, humanized monoclonal antibody designed to selectively block fibrin’s inflammatory epitope while preserving normal blood coagulation. By targeting fibrin-driven inflammation, the therapy aims to interrupt the underlying neuroinflammatory cascade associated with retinal degeneration.

In a recently published study in the Journal of Neuroinflammation (Kantor et al., 2026), Therini demonstrated that THN391 was as effective as VEGF antagonists in containing leakage from neovascular lesions in preclinical models, supporting its potential as a novel therapeutic approach for retinal vascular diseases.

The ongoing phase 1b multiple ascending dose study is designed to evaluate the safety and preliminary efficacy of THN391 in patients with DME. The trial will include three dose cohorts, with each patient receiving three monthly intravitreal injections. In addition to safety assessments, the study will evaluate biological activity using endpoints including retinal central subfield thickness, visual acuity, and exploratory biomarkers. Initial data from the study is expected in the fourth quarter of 2026.

“The dosing of the first cohort of patients in our THN391 trial represents a significant milestone for Therini Bio,” said Joel Naor, MD, MSc., Chief Medical Officer, Ophthalmology at 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. We look forward to evaluating the results of this trial and advancing THN622 toward the clinic.”

Therini also announced the advancement of THN622, a bispecific antibody targeting both fibrin’s inflammatory epitope and vascular endothelial growth factor (VEGF). The therapy is being developed for retinal conditions characterized by vascular dysfunction, including DME. THN622 combines VEGF blockade with a novel fibrin-targeting mechanism designed to address the underlying neuroinflammation that contributes to disease progression. Therini believes the dual mechanism could potentially improve treatment efficacy, increase response rates and durability, reduce fibrosis, and establish a new standard of care for neurodegenerative ocular diseases.