BRISBANE, Calif., August 6, 2026

Annexon, Inc. announced encouraging early clinical results from the ongoing FORWARD open-label study, with the first U.S. and European cohort of Guillain-Barré syndrome (GBS) patients demonstrating rapid and clinically meaningful improvement following treatment with tanruprubart. The investigational first-in-class C1q-targeted immunotherapy produced positive responses in all 10 treated patients within the first week, reinforcing previously reported findings from the company’s Phase 3 clinical trial and real-world evidence studies. The results further strengthen Annexon’s goal of positioning tanruprubart as the first approved targeted therapy for GBS, a rare and potentially life-threatening neuroinflammatory disease that currently lacks FDA-approved targeted treatments. The company expects the FORWARD study to support a planned Biologics License Application (BLA) submission in the fourth quarter of 2026, while the therapy is already under regulatory review by the European Medicines Agency (EMA).

Patients Showed Significant Recovery Within Days of Treatment

The initial FORWARD cohort included 10 adult and pediatric patients ranging from 12 to 78 years of age with moderate-to-severe Guillain-Barré syndrome. Following a single intravenous 30 mg/kg dose of tanruprubart, every patient demonstrated rapid improvement in muscle strength within four days, highlighting the therapy’s potential to interrupt the underlying disease process. Four patients who had been confined to bed regained the ability to walk with or without assistance between days two and eight, while one patient requiring mechanical ventilation was successfully removed from ventilatory support within four days. The remaining participants also experienced marked functional improvement within 48 hours. Tanruprubart was generally well tolerated, with adverse events primarily reflecting complications associated with Guillain-Barré syndrome rather than the investigational therapy itself, supporting the favorable safety profile previously observed in Phase 3 development.

FORWARD Findings Reinforce Consistent Clinical Benefit

The encouraging FORWARD data closely mirror the outcomes previously reported in Annexon’s pivotal Phase 3 program, where approximately 90% of treated patients achieved rapid and clinically meaningful improvement by Day 8. Investigators emphasized that the speed and consistency of neurological recovery suggest tanruprubart may directly halt complement-driven nerve damage instead of simply providing supportive care, representing a potentially transformative approach to treating Guillain-Barré syndrome. By specifically blocking C1q, the initiating molecule of the classical complement pathway, tanruprubart is designed to rapidly reduce inflammation and protect peripheral nerves, allowing patients to recover strength, regain mobility, and shorten hospitalization. Given that GBS affects approximately 22,000 patients annually across the United States and Europe and contributes to an estimated annual U.S. healthcare burden exceeding $20 billion, the therapy could address a substantial unmet medical need.

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Regulatory Progress Positions Tanruprubart for Potential Approval

Building on these positive findings, Annexon plans to present additional FORWARD data at upcoming scientific meetings while continuing enrollment across the United States and Europe. The ongoing study is designed to evaluate pharmacokinetics, pharmacodynamics, biomarkers, functional recovery, and safety in both adult and pediatric patients, supporting a broad future label. Tanruprubart has already received FDA Fast Track and Orphan Drug designations, as well as Orphan Drug designation from the EMA, reflecting its potential importance in addressing a disease with limited therapeutic options. With the EMA currently reviewing the Marketing Authorisation Application and the BLA submission targeted for Q4 2026, Annexon continues to advance tanruprubart toward becoming the first targeted therapy approved for Guillain-Barré syndrome, offering hope for faster recovery, improved independence, and better long-term outcomes for patients living with this devastating neurological disorder.

Source:Annexon, press release