Tanruprubart Demonstrates Rapid Recovery in Guillain-Barré Syndrome, Supporting 2026 BLA Submission
核心洞察
Tanruprubart (搜索), a first-in-class C1q (搜索) inhibitor, showed a 2.4-fold higher odds of better health at week 8 versus placebo in a phase 3 GBS trial.
Patients treated with tanruprubart (搜索) walked independently a median of 31 days earlier and spent 28 fewer days on mechanical ventilation compared to placebo.
Initial FORWARD study data showed all 10 patients had rapid, clinically meaningful improvement in muscle strength within four days of a single infusion.
Annexon Biosciences (搜索)' investigational therapy tanruprubart (搜索) (ANX005) has demonstrated rapid and clinically meaningful improvements in patients with Guillain-Barré syndrome (搜索) (GBS), according to phase 3 results presented at the 2026 European Academy of Neurology Congress and early data from the ongoing FORWARD study. The findings position tanruprubart as a potential first-in-class targeted therapy for a disease that, in the 110 years since it was first described, has lacked an approved treatment in the United States.
GBS is a life-threatening neuroinflammatory disease driven by antibody-mediated activation of the classical complement pathway, leading to rapid nerve damage, weakness, loss of mobility, and respiratory failure. Approximately 22,000 patients are affected annually across the U.S. and Europe, with an estimated annual healthcare burden exceeding $20 billion in the U.S. alone. Mortality rates reach up to 10% generally and nearly 25% in patients over age 65 within one year of hospitalization.
Mechanism of Action: Targeting C1q (搜索) at the Source
Tanruprubart (搜索) is a single-administration, intravenous therapy that binds to and rapidly inhibits C1q (搜索), the initiating molecule of the classical complement pathway. "C1q, the initiating molecule of the classical complement pathway, drives complement-mediated neuroinflammation and nerve damage," said Henk-André Kroon, MD, MBA, head of translational medicine at Annexon. "By targeting C1q, tanruprubart can potentially interrupt a key driver of complement-mediated neuroinflammation and nerve injury."
Existing treatments such as intravenous immunoglobulin (IVIg) and plasma exchange work by reducing pathogenic antibody load but do not target the underlying mechanism of nerve injury. As a result, up to half of patients show no improvement on the GBS Disability Score (GBS-DS) after 4 weeks, and approximately 25% return to pre-GBS function levels 6 months after treatment, according to 2016 data published in the Journal of Neurology, Neurosurgery and Psychiatry.
Phase 3 Trial Results
The phase 3, double-blind, placebo-controlled study enrolled 242 participants aged 16 years and older with GBS, randomized to receive a single 30 mg/kg IV infusion of tanruprubart (搜索), a single 75 mg/kg infusion, or placebo. Participants fell on levels 3 through 5 of the GBS-DS scale and were within 10 days of weakness onset.
At week 1, the 30 mg/kg group demonstrated a greater than 10-point improvement in mean change in Medical Research Council sum score for muscle strength compared with placebo (P = .0001). The adjusted odds ratio (aOR) for GBS-DS improvement was 7.2 (95% CI, 3.07-16.96), indicating a 7.2-fold higher odds of being in a better state of health. Among the 79 patients in this group, 39% scored either 2 or 3 on the GBS-DS scale versus 19% in the placebo group, and 6% achieved scores of 0 or 1—considered a good state of health—while no placebo patients reached that threshold.
At week 8, the 30 mg/kg group maintained an aOR of 2.4 compared with placebo (95% CI, 1.29-4.5).
Early Treatment and Biomarker Associations
The researchers identified a strong association between earlier treatment and better outcomes. Patients treated within 4 days of weakness onset had an aOR of nearly 7 at week 8 (95% CI, 1.10-43.25), compared with an aOR of approximately 2.5 for those treated within 8 days (95% CI, 1.23-4.86).
Serum neurofilament light (NfL) levels also correlated with outcomes. Patients in the 30 mg/kg group with NfL below 115 pg/mL had an aOR of 4.57, while those with higher NfL levels showed progressively lower but still significant odds ratios.
Functional Recovery and Healthcare Utilization
The 30 mg/kg group walked independently a median of 31 days earlier than placebo (56 vs. 87 days; P = .0211) and spent a median of 28 fewer days on mechanical ventilation (20 vs. 48 days; P = .0356). ICU stays were reduced by a median of 7 days (25 vs. 32 days), though this difference did not reach statistical significance.
"Both the early improvement during the progressive phase and improved long-term outcomes are important," Kroon told Healio. "Fatigue measures also generally favored tanruprubart (搜索), and more patients reported being 'very much improved' by day 8."
FORWARD Study: Real-World Confirmation
Initial data from Annexon's ongoing open-label FORWARD study, which enrolled the first 10 U.S. and European patients, reinforced the phase 3 findings. All patients showed rapid, clinically meaningful improvement in muscle strength within four days of a single 30 mg/kg infusion. Four patients who were bedbound early in their disease walked with or without assistance between day two and eight. One patient requiring ventilation came off the ventilator within four days, and five other patients showed marked functional gains within 48 hours.
The cohort included both male and female patients ranging from 12 to 78 years old, covering moderate to severe disease. Tanruprubart (搜索) was generally well-tolerated, with most common adverse events related to GBS or disease complications, consistent with phase 3 results.
"The early results from the FORWARD study are some of the most encouraging we have seen in GBS research and reinforce the potential of tanruprubart (搜索) as a transformative treatment," said Rafid Mustafa, MD, Associate Professor of Neurology and Vice Chair for Quality, Department of Neurology, Mayo Clinic. "Restoring strength and mobility is not simply a clinical milestone; it is a pathway back to independence, dignity, and everyday life."
Thomas Harbo, MD, PhD, Professor of Neurology at Aarhus University and Consultant Neurologist at Aarhus University Hospital in Denmark, added: "The speed of responses with tanruprubart (搜索) are striking. Patients who may have otherwise faced an uncertain road to recovery showed remarkable improvements in strength within days, translating into enhanced function and early mobilization."
Regulatory Pathway and Next Steps
Tanruprubart (搜索) has received Fast Track and Orphan Drug designations from the FDA, as well as orphan drug designation from the EMA. The Marketing Authorisation Application is currently under review by the EMA, with potential approval in the first half of 2027. Annexon intends to submit a Biologics License Application to the FDA in Q4 2026.
The FORWARD study continues to enroll adult and pediatric patients in the U.S. and Europe, evaluating pharmacokinetics, pharmacodynamics, early impact on function and biomarkers, and safety. Data from FORWARD will be presented at upcoming medical conferences and are expected to support the BLA submission.
Douglas Love, president and CEO of Annexon, stated: "The early and marked improvements in this initial data from FORWARD are consistent with our Phase 3 and Real World Evidence findings. That consistency continues to strengthen the significant functional outcomes being achieved with our differentiated C1q (搜索)-focused approach targeting neuroinflammation at its source."