Annexon (ANNX) Reports Positive Phase 3 Results for GBS Treatment

Brisbane, Calif., June 4, 2024 * Annexon, Inc. (NASDAQ: ANNX) has just announced positive topline results from its pivotal phase 3 trial in patients with Guillain-Barré Syndrome (GBS). The trial, which enrolled 241 subjects in Bangladesh and the Philippines, evaluated two doses of anx005, 30 mg/kg and 75 mg/kg.

The phase 3 trial met its primary endpoint, with anx005 30 mg/kg achieving a highly statistically significant 2.4-fold improvement on the GBS-Disability Scale (GBS-DS) at week 8 (proportional odds analysis, p = 0.0058). Anx005 30 mg/kg treatment also demonstrated improvements versus placebo on key secondary endpoints, including early gains in muscle strength by Medical Research Council (MRC) sum score at day 8 (p <0.0001) and at week 8 (p = 0.0351), and a median of 28 fewer days on artificial ventilation through week 26 (p = 0.0356). Additionally, anx005 30 mg/kg demonstrated a 31-day reduction in the median time to walk independently versus placebo (p = 0.0211) in a prespecified analysis.

Anx005 75 mg/kg outperformed placebo on multiple endpoints, however, it was not statistically significant on the primary endpoint of GBS-DS at week 8 (p = 0.5548).

The clinical safety and tolerability findings of anx005 at both doses in the phase 3 study support a generally well-tolerated profile with no new safety signals. The majority of adverse events were mild grade 1 to moderate grade 2 events. The most common treatment-related adverse events were infusion-related reactions (30.4%) that were mostly mild transient rashes. There were no autoimmune related adverse events, and no drug-related deaths or serious infections were observed.

Real-world evidence (RWE) comparability data are expected in the first half of 2025. Annexon has initiated a real-world evidence (RWE) protocol with the International Guillain-Barré Syndrome Outcomes Study (IGOS) to establish comparability between phase 3 participants and Western patients.

Anx005 has been granted fast track and orphan drug designations from the FDA. Anx005 has also been granted orphan drug designation by the European Medicines Agency (EMA).

Annexon plans to present phase 3 data at the 2024 Peripheral Nerve Society Annual Meeting on June 25, 2024.

This breakthrough in effectively tackling GBS highlights the potential of anx005 to address the significant unmet need in this vulnerable patient population and represents a potentially transformative advancement for the treatment landscape.

The market has reacted to these announcements by moving the company's shares 31.7% to a price of $6.03. Check out the company's full 8-K submission here.

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