Annexon Expands Macular Degeneration Trial With New 24-Month Vonaprument Endpoint

Key Points

• Annexon added a Month 24 dual-primary endpoint to the ongoing ARCHER II Phase 3 trial of vonapramide in geographic atrophy.
• The original Month 15 primary endpoint remains unchanged, with an independent Data Monitoring Committee review expected in Q4 2026.
• If the Month 15 endpoint succeeds, Annexon expects detailed sub-study results in Q1 2027; if not, the study can continue to the Month 24 analysis in Q3 2027.

Annexon Biosciences (Nasdaq: ANNX) is broadening the Phase 3 development plan for vonaprument, its investigational therapy for geographic atrophy caused by dry age-related macular degeneration. The new design adds a separate Month 24 primary analysis while preserving the existing Month 15 endpoint, providing two distinct opportunities to demonstrate a meaningful reduction in vision loss.

ARCHER II will assess vonaprument at both 15 and 24 months

The global ARCHER II trial is evaluating whether monthly intravitreal vonaprument injections can reduce the risk of confirmed clinically meaningful vision loss. The original Month 15 primary endpoint will remain in place, while the new Month 24 endpoint will allow Annexon to evaluate whether treatment benefit becomes clearer with longer follow-up.

The study can be considered successful if it meets the primary endpoint at either timepoint. Annexon said no operational changes are required because the trial was already designed to stay blinded through Month 24.

Q4 2026 data review remains the nearest major catalyst

The independent Data Monitoring Committee is expected to assess the Month 15 primary endpoint during the fourth quarter of 2026. If the trial meets that endpoint, Annexon expects to report results from its two pre-specified sub-studies in the first quarter of 2027.

If the Month 15 endpoint is not met, the study may continue to the Month 24 analysis, which is expected to be completed in the third quarter of 2027. This means the updated trial structure extends the timeline for a definitive readout while preserving the opportunity for longer-term clinical data.

Trial enrollment, treatment compliance, and extension study support long-term data collection

ARCHER II enrolled 659 people with geographic atrophy and is evaluating the proportion of patients who experience confirmed best-corrected visual-acuity loss of at least 15 letters, equal to three lines on a standard eye chart.

Annexon said all eligible participants have completed at least 12 months of treatment, with discontinuation below 10% and compliance above 95%. After Month 24, eligible participants may enroll in an open-label extension study to receive monthly vonaprument and provide additional long-term safety and efficacy data.

Vonaprument targets complement-driven retinal damage

Vonaprument, formerly known as ANX007, is designed to block C1q, the first component of the classical complement pathway. Annexon believes this mechanism may protect photoreceptors and preserve visual function in geographic atrophy while leaving other complement pathways active.

The therapy has FDA Fast Track designation and EMA PRIME designation, but it remains investigational. Its future will depend on whether ARCHER II produces statistically significant, clinically meaningful vision-preservation results with an acceptable safety profile.