Annexon (ANNX) Study Result summary

Study background and objectives

• ANX005 is a targeted anti-C1q immunotherapy designed to halt neuroinflammation and nerve damage in Guillain-Barré Syndrome (GBS), a severe acute neurological disease with no FDA-approved treatments and significant unmet need.

• Real-world evidence (RWE) and phase III studies compared ANX005-treated patients to propensity-matched IGOS registry patients who received IVIG or plasma exchange, using consistent analytical/statistical methods.

• The phase III trial was conducted in Bangladesh and the Philippines, enabling a placebo-controlled design due to limited IVIG/plasma exchange availability.

• Approximately 22,000 patients are hospitalized annually in the US and Europe for GBS, highlighting the disease's significant burden.

• The company plans to submit a Biologics License Application (BLA) in the US in the first half of 2025.

Study design and methodology

• The RWE study used a 1:1 matched cohort from the IGOS registry and phase III trial, each with 79 patients matched on key prognostic factors.

• Propensity score matching and blinded methodology ensured comparability between cohorts.

• IGOS registry patients received standard of care (IVIG or plasma exchange), while ANX005 was administered as a single 30 mg/kg intravenous dose.

• The study focused on moderate to severe GBS cases, reflecting a broad global patient spectrum.

• Efficacy was measured using muscle strength (MRC sumscore), GBS Disability Scale (GBS-DS), and need for mechanical ventilation.

Key efficacy and safety findings

• ANX005-treated patients showed over a 10-point improvement in muscle strength by week 1 compared to IVIG/plasma exchange (p<0.0001), a statistically significant and unprecedented early effect.

• Patients on ANX005 were about twice as likely to be in a better health state on the GBS Disability Scale at multiple timepoints, including week 8 (p=0.0459).

• Fewer ANX005 patients required mechanical ventilation (19% vs 40.5%; 15/79 vs 32/79; p=0.022), and those who did spent a median of 12 fewer days on ventilation or in ICU.

• ANX005 demonstrated early, robust, and durable effects, expediting recovery and reducing time to walking by about one month in prior phase III data.

• The safety profile of ANX005 was generally well tolerated, with mild to moderate infusion-related events, no new safety signals, and no increased infection rates.