Hansa Biopharma's investigational enzyme therapy imlifidase has demonstrated promising results in treating severe Guillain-Barré syndrome (GBS), showing rapid functional recovery and a favorable safety profile in a phase 2 clinical trial presented at the 2025 Peripheral Nerve Society Annual Meeting in Edinburgh, Scotland.
The open-label, single-arm study enrolled 27 patients with confirmed severe GBS who received imlifidase 0.25 mg/kg intravenously within 12 days of symptom onset, followed by standard intravenous immunoglobulin (IVIg) therapy 48 hours later. After 8 weeks of treatment, 67% of patients were able to walk independently, 40.7% had regained the ability to run, and 37% showed improvement of at least 3 points on the GBS Disability Scale.
Mechanism and Rationale
Imlifidase is a first-in-class enzyme derived from Streptococcus pyogenes that specifically cleaves human IgG molecules, converting them into Fc and F(ab')2 parts and eliminating Fc-mediated functions. According to Elisabeth Sonesson, PhD, VP, Franchise Lead, Autoimmune at Hansa Biopharma, the treatment rapidly reduces IgG levels to below detection limits within hours and maintains suppression for approximately one week.
"The rationale for using this in GBS is that a key driver of the disease is IgG autoantibodies directed against gangliosides, which mediate the inflammatory damage to peripheral nerves," Sonesson explained. "The specific and fast mode of action of our molecule may translate into clinical benefit by rapidly removing the antibodies that cause this damage."
Trial Design and Results
The study, designated 15-HMedldeS-09, was conducted across France, the UK, and the Netherlands. Initially enrolling 30 patients, three were later re-diagnosed with other conditions, leaving 27 patients in the final analysis. All participants had severe GBS defined as a GBS disability score of 3 or higher.
Patients demonstrated rapid functional improvement, with GBS disability scores improving quickly after imlifidase treatment and MRC sum scores rising from 39 to 50 in just the first week. When compared with the IGOS cohort, patients treated with imlifidase and IVIg regained the ability to walk six weeks earlier than those treated with IVIg alone.
Safety Profile
The treatment demonstrated a favorable safety profile with no significant concerns identified. No treatment-emergent adverse events led to discontinuation, and only one infusion-related reaction required a temporary pause, though the full dose was still administered. No clinically relevant changes were observed in ECGs, vital signs, or infection rates.
Addressing Unmet Medical Need
Current standard-of-care treatments for GBS include plasma exchange and IVIg therapy, both of which have limitations in terms of speed and specificity. Sonesson noted that 25% of GBS patients require mechanical ventilation, and many remain unable to walk a year after diagnosis.
"It brings specificity and speed," Sonesson said regarding imlifidase's potential advantages. "Imlifidase specifically removes pathogenic antibodies very rapidly. Current standard-of-care IVIG takes five days to administer and has a slower onset of action."
Future Development
Hansa Biopharma plans to publish the results in a peer-reviewed journal before defining next steps for clinical development. The company is currently evaluating the path forward for imlifidase in GBS treatment, building on these encouraging phase 2 results.
Imlifidase is already approved in the European Union for desensitizing kidney transplant patients, providing a foundation for its safety profile in other autoimmune applications. The rapid onset of action and specific targeting of pathogenic antibodies position it as a potentially transformative treatment option for GBS patients who currently face limited therapeutic alternatives.
