Annexon Biosciences: ANX005 Antibody Shines in Phase 3 Trials For Treatment Of Guillain-Barré Syndrome

1. ANX005 led to significant reductions in GBS-associated disability, improved muscle power, reduced nerve damage, and a reduced need for mechanical ventilation.
2. ANX005 was well-tolerated with an infusion-related transient rash being the most common adverse effect.

The Latest

In a randomized, phase 3 clinical trial funded by Annexon Biosciences, researchers investigated the efficacy of ANX005 in the treatment of Guillain-Barré syndrome (GBS). The clinical trial met its primary and major secondary endpoints. ANX005 demonstrated a 2.4-fold statistically significant improvement in GBS-associated disability measured by the GBS disability scale. ANX005 also successfully demonstrated long-term improvements in muscle power and nerve damage. Patients on ANX005 also required significantly less time on mechanical ventilation. The drug was well tolerated and safe, with the most common adverse effect being a mild infusion-associated transient rash. This study was conducted in Bangladesh and the Philippines due to the high incidence of GBS in these nations, and the low availability of intravenous immunoglobulin (IVIg). Based on the success of this trial and feedback from the FDA, Annexon will now collaborate with the Inflammatory Neuropathy Consortium to investigate the efficacy of ANX005 on a larger scale in Western patients.

Physician’s Perspective

GBS is an autoimmune-mediated insult on the nerves which occurs after a bacterial or viral infection. Intestinal infection with Campylobacter jejuni is the most common etiology. GBS occurs approximately 2-6 weeks after infection and progresses rapidly. Symptoms include ascending paralysis, pain in the extremities and back, and respiratory muscle involvement among others. GBS can be diagnosed by clinical history and physical exam but requires a lumbar puncture to confirm the diagnosis. A major life-threatening complication of GBS is respiratory failure. Presently the treatment for GBS is IVIg therapy which is non-curative and only helps to ease the burden of symptoms. Annexon’s ANX005 is a novel approach to treating GBS because it targets upstream molecular pathways to halt the rapid progression of GBS.

Molecular Target of Therapy

ANX005 is a monoclonal antibody that targets the complement pathway—a pathway part of the innate immune system implicated in the neuroinflammatory processes that lead to nerve injury seen in GBS. ANX005 specifically acts against the C1q protein complex in the complement pathway. When antigen-antibody complexes bind to this protein complex, the complement pathway is initiated. By targeting the complement pathway at this point, ANX005 works to arrest the immune response at the immediate onset.

Company History

Annexon Biosciences is a biopharmaceutical company based in California, USA. The company’s focus is on complement-mediated neurological and ophthalmological disorders. In addition to GBS, ANX005 is also conducting phase 2 clinical trials for the treatment of Huntington’s disease and amyotrophic lateral sclerosis. The company is also working on ANX007, a monoclonal antibody in phase 2 clinical trials for the treatment of geographic atrophy.

Further reading: https://ir.annexonbio.com/news-releases/news-release-details/annexon-announces-positive-topline-results-pivotal-phase-3-trial

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