Tanruprubart Shows Early, Sustained Quality-of-Life Improvements in Phase 3 GBS Trial

Recently presented at the 2025 Peripheral Nerve Society (PNS) Annual Meeting, held May 17-20, in Edinburgh, Scotland, investigators reported that patients with Guillain-Barré syndrome (GBS) who received the investigational monoclonal antibody tanruprubart (Annexon Biosciences), formerly known as ANX005, in a phase 3 trial (NCT04701164) demonstrated early, sustained improvements in perceived disability and quality-of-life measures.¹

The analysis included 241 patients with GBS aged 16 years and older who were randomized to receive a single IV infusion of ANX005 at either 30 mg/kg, 75 mg/kg, or placebo. Patients in the 30 mg/kg group showed significant improvement on the EQ visual analog scale (EQ-VAS) at the first time point measured at week 1 (P = .0089), which remained through week 8 (P = .0391), based on a mixed model for repeated measures (MMRM). Improvements in perceived disability, measured by the Patient Global Impression of Change (PGIC), were also observed by week 1.

Presented by lead author Glenn Morrison, PhD, vice president of clinical development at Annexon Biosciences, significant improvements were reported at week 1 in the ANX005-treated groups using proportional odds regression for the EQ5D-5L domains including mobility (OR = 5.65; P <.0001), self-care (OR = 9.50; P <.0001), and usual activity (OR = 7.42; P <.0001). These benefits continued over the first 8 weeks of the study. Additionally, the 30 mg/kg group experienced a 20% improvement in the country-standardized index score after 1 week of treatment (MMRM, P <.0001).

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Previously presented data from the phase 3 trial revealed that single dose of ANX005 at 30 mg/kg doses led to significant and sustained improvement in patient health for those with GBS over a 6-month period. Presented at 2025 American Academy of Neurology (AAN) Annual Meeting, held April 5-9 in San Diego, California, results showed that both doses of ANX005 inhibited complement; however, only the 30 mg/kg dose group achieved the primary outcome of change in GBS Disability score (GBS-DS) trichotomy.

All told, those assigned to the ANX005 30 mg/kg group had 2.4-times greater odds of improved health at week 8 relative to placebo (OR, 2.4; 95% CI, 1.29-4.50; P = .0058), all while maintaining a safe profile. Notably, patients started to see improvements in function as early as week 1 of treatment (OR, 7.2; 95% CI, 3.07-16.96; P <.001). By the end of the study period, 2.5-times more treated patients returned to normal health (OR, 4.1; 95% CI, 1.422-12.04; P = .0092) relative to placebo. In addition, these patients also walked independently a median 31 days earlier (P = .0211) and spent a median 28 days less on mechanical ventilation (P = .0356) compared with placebo.

In terms of safety, the profiles of patients on the treatment were comparable across groups, with a balanced number of serious AEs observed. Overall, transient infusion-related reactions were found in 35.0% of treated patients with ANX005; however, this did not impact morality or infection rates. Investigators concluded that based on these findings, the agent has therapeutic potential to “transform” GBS management.

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REFERENCES
1. Glenn Morrison, Ping Lin, Quazi Deen Mohammad, et al. ANX005 improves health-related quality of life in patients with GBS compared to placebo. Presented at: 2025 Peripheral Nerve Society (PNS) Annual Meeting; May 17-20; Edinburgh, Scotland. P338.
2. Kroon HA, Islam Z, Collins P, et al. Efficacy and Safety of Targeted Immunotherapy with ANX005 in Treating Guillain-Barré Syndrome: A Phase 3 Multicenter Study. Presented at: 2025 AAN Annual Meeting; April 5-9; San Diego, CA. ABSTRACT 004954