C1q Inhibitor Tanruprubart Shows Functional Benefit in Guillain-Barré Syndrome

KEY TAKEAWAYS

• Tanruprubartimproved functional recovery in Guillain-Barré syndrome, meeting the primary end point of a phase 3 trial.
• Earlier treatment after symptom onset and lower baseline neurofilament light levels were associated with greater benefit.
• Tanruprubart was generally well tolerated, with most adverse events attributed to GBS rather than study treatment.

Early treatment with tanruprubart (ANX005; Annexon Biosciences, Brisbane, CA) improved functional recovery in adults with Guillain-Barré syndrome (GBS), according to phase 3 GBS-02 results presented at the 2026 Annual Meeting of the American Academy of Neurology (AAN). Participants receiving the 30 mg/kg dose demonstrated rapid improvement by Week 1 and met the study's primary end point at Week 8. Tanruprubart is an investigational intravenously-delivered drug that targets C1q, a component of the classical complement pathway, offering a mechanism-directed approach to GBS that differs from other immunomodulatory treatments such as immunoglobulin and plasma exchange.

The double-blind, placebo-controlled trial enrolled 242 adults aged 16 years or older with GBS disability scores of 3 to 5 who were within 10 days of weakness onset and did not have access to intravenous immunoglobulin or plasma exchange. Participants were randomized to receive a single intravenous infusion of tanruprubart 30 mg/kg, tanruprubart 75 mg/kg, or placebo and were followed for 26 weeks. The primary end point was Guillain-Barré syndrome disability score (GBS-DS) at Week 8.

What the Study Found

• At Week 1, tanruprubart 30 mg/kg increased the odds of achieving a better health state versus placebo (adjusted odds ratio [aOR], 7.2; P<.001).
• At Week 8, tanruprubart met the primary endpoint, improving GBS-DS versus placebo (aOR, 2.4; 95% CI, 1.29–4.50; P=.0058).
• Participants treated earlier after weakness onset and those with lower baseline serum neurofilament light (NfL) concentrations experienced greater functional improvement.
• Most adverse events were mild to moderate and were considered related to GBS rather than study treatment.

The study authors stated that early C1q inhibition may improve recovery in GBS, particularly before substantial axonal injury develops, and suggested that baseline NfL may help identify patients most likely to benefit from treatment.

Source

Kroon HA, Islam Z, Navarro J, et al. Early Targeted C1q Inhibition With Tanruprubart Improves Functional Recovery in Guillain-Barré Syndrome: Results From a Phase 3 Study. Presented at the American Academy of Neurology Annual Meeting; April 18–22, 2026; San Diego, CA.