Positive phase 3 results reported in study of Guillain-Barre treatment

Annexon Biosciences has announced positive topline results from a phase 3, randomized placebo-controlled clinical trial examining an investigational monoclonal antibody in those with Guillain-Barré syndrome.

According to a company press release, the study met its primary endpoint, with a dose of ANX005 at 30 mg/kg achieving a 2.4-fold improvement on the GBS-disability scale (GBS-DS) at week 8. The treatment also demonstrated superiority compared with placebo on key secondary endpoints including early gains in muscle strength measured by Medical Research Council sum score at day 8 and at week 8, along with a median of 28 fewer days on artificial ventilation through week 26.

“Our phase 3 results reinforce that early treatment with ANX005 halted disease progression and helped patients get better sooner, supporting its potential to be the first targeted therapy for [Guillain-Barre syndrome] in the United States,” Douglas Love, president and CEO of Annexon, told Healio in an email. “These findings confirm the core thesis upon which Annexon was established: that inhibiting upstream C1q can stop neuroinflammation.”

The study, which enrolled 241 participants in Bangladesh and the Philippines, evaluated two doses of ANX005, 30 mg/kg and 75 mg/kg, during which 30 mg/kg dose suppression lasted 1 week and the 75 mg/kg dose suppression lasted 2 to 3 weeks.

Safety and tolerability findings of ANX005 at both doses supported a generally well-tolerated profile with no new safety signals, according to the release. The majority of adverse events were mild to moderate, and the most common treatment-related adverse events were infusion-related reactions. No autoimmune related adverse events, drug-related deaths or serious infections were reported.

ANX005 had previously been granted fast track and orphan drug designations from the FDA, while also receiving orphan drug designation by the European Medicines Agency.