Key Takeaways

  • Annexon added a Month 24 dual primary endpoint to ARCHER II while retaining the phase 3 trial’s Month 15 primary endpoint
  • An independent DMC is expected to assess the Month 15 primary endpoint in the fourth quarter of 2026, with sub-study results potentially following in the first quarter of 2027

Annexon has added a 'Month 24' dual primary endpoint to its phase 3 ARCHER II trial evaluating vonaprument in patients with geographic atrophy (GA), while retaining the study’s existing 'Month 15' primary endpoint. The company also announced the launch of an open-label extension study designed to evaluate the long-term safety and potential benefit of vonaprument in patients with GA.

According to Annexon, the dual primary endpoint strategy gives ARCHER II the opportunity to demonstrate protection against vision loss at either Month 15 or Month 24 as independent efficacy timepoints. The company expects an independent Data Monitoring Committee (DMC) assessment of the Month 15 primary endpoint in the fourth quarter of 2026.

“Our objective is to maximize the best-in-class potential of vonaprument to preserve visual acuity for millions of patients at risk of irreversible vision loss,” said Douglas Love, president and CEO of Annexon.

Mr. Love noted that ARCHER II was already designed to remain masked through Month 24, allowing the additional endpoint to be incorporated without changing study operations. He added that the company remains on schedule for the Month 15 data milestone in the fourth quarter of 2026, with Month 24 results to follow as a separate assessment.

ARCHER II is an ongoing global, double-masked phase 3 trial. Annexon reported that all eligible patients have received at least 12 months of treatment and that masked event accrual remains in line with projections. The company also reported a discontinuation rate of less than 10% and treatment compliance exceeding 95%.

After patients complete Month 24, they will have the option to receive monthly vonaprument in the open-label extension study.

Under the revised analysis plan, the independent DMC will assess the overall study’s primary endpoint at Month 15. If the DMC determines that ARCHER II has met the Month 15 primary endpoint, the company plans to proceed with analyses of the trial’s 2 sub-studies, with those results expected in the first quarter of 2027.

Alternatively, the DMC may recommend continuing the study to the Month 24 primary endpoint analysis. Annexon expects completion of ARCHER II, including the Month 24 analyses, in the third quarter of 2027.

Vonaprument, formerly known as ANX007, is an investigational antigen-binding fragment designed to selectively inhibit C1q, the initiating molecule of the classical complement pathway. The intravitreally administered therapy is being developed as a neuroprotective approach intended to preserve photoreceptor cells and retinal function while leaving the lectin and alternative complement pathways intact.

The investigational therapy has received Fast Track designation from the US Food and Drug Administration and Priority Medicines designation from the European Medicines Agency (EMA) for GA. Annexon said vonaprument was also selected for the EMA’s Product Development Coordinator pilot, which launched in July 2025 to assist PRIME-designated programs with regulatory interactions and development activities.