Annexon to present ARCHER II baseline data at Retina Society meeting
Annexon Biosciences has announced two oral presentations on its lead candidate vonaprument at The Retina Society 59th Annual Scientific Meeting, held in Los Angeles from 23 to 26 September 2026. The presentations focus on patient baseline characteristics from the ongoing Phase 3 ARCHER II trial and a post hoc vision analysis from the completed Phase 2 ARCHER study, and are positioned by the company as evidence that the Phase 3 population closely mirrors the Phase 2 cohort that generated positive efficacy signals.
Vonaprument is an antigen-binding fragment designed to selectively inhibit C1q, the initiating protein of the classical complement pathway. Formulated for intravitreal injection, it is being developed as a potential vision-protecting therapy for geographic atrophy (GA), a progressive neurodegenerative retinal disease that affects more than eight million people worldwide and is a leading cause of irreversible central vision loss. The company describes the approach as neuroprotective, aiming to preserve photoreceptor cells and retinal architecture rather than simply slowing lesion growth, the mechanism targeted by the two currently approved GA treatments.
The ARCHER programme
The completed Phase 2 ARCHER trial assessed vonaprument across a broad GA population. Annexon reports that the candidate consistently protected visual function and ellipsoid zone retinal structure, with statistically relevant, dose- and time-dependent protection from confirmed best corrected visual acuity loss of 15 letters or more. Safety data through month 12 showed no increase in choroidal neovascularisation versus sham and no events of retinal vasculitis.
ARCHER II, which enrolled 659 patients globally, was designed to replicate those Phase 2 findings with confirmed visual acuity loss as the primary endpoint at months 15 and 24. The company says baseline clinical characteristics across the two cohorts are comparable, a deliberate design strategy to support regulatory extrapolation. Month-15 primary analysis results are expected in the fourth quarter of 2026, which represents the most consequential near-term catalyst for Annexon. A global registration path has been agreed with both the FDA and EMA. Vonaprument holds FDA Fast Track designation and is the first GA candidate to receive EMA Priority Medicine designation.
Market context and competitive landscape
The geographic atrophy space became notably more competitive after Apellis Pharmaceuticals secured FDA approval for pegcetacoplan in 2023 and Iveric Bio's avacopan followed shortly after under Astellas. Both approved agents target the complement pathway, though at different points: pegcetacoplan inhibits C3, while vonaprument acts upstream at C1q. Blocking C1q preserves the lectin and alternative pathways, which Annexon argues maintains broader immune functionality. Whether that mechanistic distinction translates into a differentiated clinical or safety profile will depend heavily on the ARCHER II readout.
The GA market is projected by analysts to grow substantially over the coming decade as the global population ages, but commercial uptake of the approved therapies has been slower than many forecasters anticipated, partly reflecting the burden of monthly or every-other-month intravitreal injections. Annexon has not yet disclosed a dosing regimen for vonaprument in Phase 3, and durability of effect will be a key factor in physician and payer adoption.
With the month-15 data window now imminent, investors and retinal specialists will scrutinise whether the Phase 3 population's replication of Phase 2 baseline characteristics translates into a comparable efficacy signal. A positive readout could support an NDA and MAA filing, potentially making vonaprument the first agent to reach the market with a primary endpoint anchored to visual acuity preservation rather than lesion-growth reduction alone.