BRISBANE, Calif., August 12, 202
Annexon, Inc. announced the expansion of its ongoing Phase 3 ARCHER II trial evaluating investigational vonaprument in patients with geographic atrophy (GA) associated with dry age-related macular degeneration (AMD). The company has added a Month 24 dual primary endpoint alongside the existing Month 15 primary endpoint, creating two independent efficacy timepoints for evaluating protection against vision loss. Annexon also launched an open-label extension (OLE) study that will allow eligible patients completing Month 24 to receive monthly vonaprument treatment. ARCHER II has completed enrollment of 659 patients, and the company expects the independent Data Monitoring Committee (DMC) to assess the Month 15 primary endpoint in the fourth quarter of 2026, with completion of the Month 24 analysis expected in the third quarter of 2027. The changes are designed to evaluate both earlier and longer-term effects of vonaprument while maintaining the existing masked study structure.
Month 24 Endpoint Expands ARCHER II Evaluation
The addition of the Month 24 dual primary endpoint allows ARCHER II to evaluate vision-preservation outcomes at both Month 15 and Month 24. The trial measures the proportion of patients experiencing confirmed best corrected visual acuity (BCVA) loss of at least 15 letters at two consecutive visits, a clinically meaningful measure of vision loss. Annexon said the study was already designed to remain masked through Month 24, allowing the additional endpoint to be incorporated without changing the fundamental trial operation. The DMC will first assess the overall study at Month 15. If the Month 15 primary endpoint is met, the company plans to proceed with analyses of two sub-studies, with results expected in Q1 2027. If the Month 15 endpoint is not sufficient for overall study success, the trial can continue toward the Month 24 primary endpoint assessment. Annexon expects topline Month 15 results in Q4 2026, making the upcoming DMC assessment an important clinical milestone for vonaprument.
Vonaprument Targets Classical Complement Pathway
Vonaprument, formerly known as ANX007, is an investigational antigen-binding fragment designed to selectively inhibit C1q, the initiating molecule of the classical complement pathway. Annexon is developing the therapy as a potential vision-preserving treatment for geographic atrophy, with the goal of protecting photoreceptor cells and retinal function from neuroinflammatory damage. The company’s completed Phase 2 ARCHER study showed signals of protection against vision loss and preservation of retinal structures, including photoreceptors, although those findings do not establish that the treatment will succeed in Phase 3. In ARCHER II, all eligible patients have received at least 12 months of treatment, while masked event accumulation remains in line with projections. Annexon reported a discontinuation rate below 10% and treatment compliance above 95%. The company also stated that vonaprument has received FDA Fast Track designation and EMA PRIME designation, regulatory designations intended to facilitate development and regulatory interactions but not guarantees of approval..
Advertisement
Open-Label Extension Supports Long-Term Assessment
The newly launched open-label extension study is intended to provide additional information on the long-term safety and potential benefit of vonaprument in patients with geographic atrophy. Following completion of Month 24 in ARCHER II, eligible participants can receive monthly vonaprument treatment through the extension study. Geographic atrophy is an advanced form of dry AMD that can progressively damage retinal cells and cause irreversible central vision loss, creating a significant unmet need for therapies capable of preserving visual function. Annexon expects the Month 15 assessment in Q4 2026, potential sub-study results in Q1 2027 if the overall trial meets the relevant criteria, and completion of ARCHER II including Month 24 analyses in Q3 2027. The key near-term catalyst remains the Month 15 DMC assessment, while the additional Month 24 endpoint could provide a longer-term evaluation of vonaprument’s potential durability. Ultimately, the success of the program will depend on whether the randomized Phase 3 study demonstrates statistically and clinically meaningful protection against vision loss.
Source:Annexon, press release
