Therini Bio's THN391 heads toward first human data in DME this quarter
The Phase 1b trial targets fibrin's inflammatory epitope instead of VEGF, an approach with no direct clinical precedent, and initial safety and biomarker data are due in the fourth quarter.
Executive Summary
- Therini Bio is running a small, early-stage safety study of an antibody that blocks fibrin-driven inflammation, a mechanism distinct from the VEGF-blocking drugs that anchor current diabetic macular edema treatment.
- Because the study is a small, open-label dose-escalation design, its data will speak to tolerability and early biological activity rather than deliver a decision-grade efficacy verdict.
- The diabetic macular edema field is active with multiple late-stage VEGF-targeted programs advancing, and no competitor identified in the landscape shares this drug's fibrin-targeting mechanism, leaving the approach without a direct precedent to benchmark against.
- The trial has progressed through recruitment without protocol amendments or enrollment changes, a pattern consistent with routine early-phase conduct rather than any operational concern.
The catalyst
Therini Bio, Inc. expects to report initial data from its Phase 1b multiple ascending dose study of THN391 in diabetic macular edema (DME) in the fourth quarter of 2026, with the company's own guidance placing the window between October 1 and December 31. The trial, registered as NCT06701721, is testing intravitreal THN391 in adults with DME secondary to non-proliferative diabetic retinopathy. THN391 is a humanized monoclonal antibody designed to block fibrin's inflammatory epitope, the toxic protein deposits that accumulate when vascular integrity breaks down in the diabetic retina, without disrupting normal blood clotting. Therini+1Therini Bio Doses First Patients in Phase 1b Trial of Novel Anti-Inflammatory Therapy, THN391, ...May 27, 2026A Study Intravitreal THN391 in Diabetic Macular Oedema Secondary to Non-Proliferative Diabetic Retinopathy.NCT06701721
Probability of SuccessBased on the AppliedXL Probability of Success model. For more information about the methodology, read the research here.
The design
The study enrolls patients across three dose cohorts, with each patient receiving three monthly intravitreal injections. The primary endpoint is adverse events, making this a safety and tolerability study rather than an efficacy trial. Secondary measures include change in retinal edema and change in visual acuity, and the company's disclosure adds retinal central subfield thickness and exploratory biomarkers as measures of biological activity. Anticipated enrollment is 21 patients across sites in Australia, with a primary completion date registered as October 31, 2025. Therini Bio dosed the first patients in the trial on May 27, 2026, and the trial has held at Recruiting status since December 19, 2024 with no protocol amendments logged since. Therini+1Therini Bio Doses First Patients in Phase 1b Trial of Novel Anti-Inflammatory Therapy, THN391, ...May 27, 2026A Study Intravitreal THN391 in Diabetic Macular Oedema Secondary to Non-Proliferative Diabetic Retinopathy.NCT06701721
The mechanism and the field
Diabetic macular edema treatment is built around blocking VEGF, the target shared by the eight active competing trials identified in the indication, including late-stage programs from EyePoint Pharmaceuticals, Genentech, and Hoffmann-La Roche testing VEGF-A antagonists. None of those programs share THN391's fibrin-targeting mechanism, leaving THN391 without a same-target comparator in this indication. Therini's own preclinical work, published in the Journal of Neuroinflammation, reported that THN391 matched VEGF antagonists in containing leakage from neovascular lesions in animal models, the basis the company cites for testing the mechanism in patients. TheriniTherini Bio Doses First Patients in Phase 1b Trial of Novel Anti-Inflammatory Therapy, THN391, ...May 27, 2026
What comes next
Therini has already advanced a second-generation candidate, THN622, a bispecific antibody combining the fibrin-blocking mechanism with anti-VEGF activity, positioning it as a potential combination approach layered onto the current standard of care. Joel Naor, Therini's Chief Medical Officer for ophthalmology, said dosing the first cohort "represents a milestone for Therini Bio" and that the company looks "forward to evaluating the results of this trial and advancing THN622 toward the clinic". The Phase 1b data due this quarter will be the first human read on whether fibrin-targeted blockade behaves as the preclinical data suggested. TheriniTherini Bio Doses First Patients in Phase 1b Trial of Novel Anti-Inflammatory Therapy, THN391, ...May 27, 2026
This analysis was produced using AI-assisted reporting systems, AppliedXL data, and official public records. These systems undergo editorial review, quality checks, and regular audits by human experts. Errors may still occur, as with any automated system. Always consult the linked primary sources. Read our AI Editorial Policy.