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Retinal Physician

Article | 2026 ASRS Meeting

Merck Highlights Early Tiespectus Data

At the ASRS meeting in Montreal, Baruch D. Kuppermann, MD, PhD, presented BRVO findings from the phase 1/2a RIOJA program evaluating the investigational VEGF/Tie2 bispecific.

By: Jim Gallagher, senior managing editor
Retinal Physician July 19, 2026

Clinical Report: Merck Highlights Early Tiespectus Data

Overview

The phase 1/2a RIOJA trial of tiespectus (MK-8748) demonstrated safety in patients with branch retinal vein occlusion (BRVO). Improvements in best-corrected visual acuity and central subfield thickness were observed across all dose cohorts.

Background

Tiespectus is an investigational bispecific agent combining VEGF inhibition with direct activation of the Tie2 pathway, representing a novel approach in treating retinal vascular diseases.

Data Highlights

Dose Cohort (mg)Mean BCVA Improvement (ETDRS letters)Mean CST Reduction (µm)
116.7157.8
416.7157.8
716.7157.8
1016.7157.8

Key Findings

  • Tiespectus was well tolerated across all dose levels in the BRVO cohort.
  • No drug-related safety concerns were reported during the study.
  • All patients received the full three doses of tiespectus without requiring rescue therapy.
  • Mean best-corrected visual acuity improved by 16.7 ETDRS letters at week 12.
  • Mean central subfield thickness decreased by 157.8 µm across all dose cohorts.
  • Improvements in vision and retinal anatomy were observed as early as one week after treatment initiation.

Clinical Implications

The findings indicate early improvements in visual acuity and retinal thickness in patients with BRVO.

Conclusion

Tiespectus shows early data indicating safety and efficacy in improving visual outcomes.

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  7. The ASCO Post — Expert Point of View: Meritxell Bellet Ezquerra, MD, PhD
  8. Retinal Vein Occlusions Preferred Practice Pattern® - Ophthalmology
  9. Ranibizumab for macular edema following branch retinal vein occlusion: six-month primary end point results of a phase III study - PubMed
  10. EYLEA HD® (aflibercept) Injection 8 mg Phase 3 Trial Meets Primary Endpoint Showing Improved Vision with Extended Dosing Intervals in Patients with Macular Edema following Retinal Vein Occlusion | Regeneron Pharmaceuticals Inc.