Efgartigimod Shows Promise for Chronic Inflammatory Demyelinating Polyneuropathy

Patients with chronic inflammatory demyelinating polyneuropathy (CIDP) who received efgartigimod PH20 vs placebo demonstrated a significantly decreased risk for clinical deterioration, according to study results presented at the 2024 American Academy of Neurology (AAN) annual meeting, held from April 13 to 18, 2024, in Denver, Colorado.

Although there are treatment options available for patients with CIDP, patients continue to experience significant symptoms. Researchers have conducted studies of the use of efgartigimod, a human immunoglobulin G (IgG) 1 antibody Fc fragment, for this disease state. This monoclonal antibody works by blocking the ​​neonatal Fc receptor (FcRn) thereby reducing the recycling of IgG which decreases the pathogenic IgG autoantibody levels that are potentially play a role in CIDP development. 

The ADHERE study (ClinicalTrials.gov Identifier: NCT04281472) was a two-part, multicenter, randomized, double-blinded, placebo-controlled trial to evaluate the safety and efficacy of efgartigimod in patients with CIDP. 

Patients received efgartigimod, which was formulated with recombinant human hyaluronidase PH20, subcutaneously. Study eligibility included adults with a confirmed diagnosis of CIDP who were previously receiving the standard treatment or were treatment naïve. 

The open-label portion (Stage A) of the study enrolled patients with active disease who received 1000 mg efgartigimod PH20 subcutaneously weekly for up to 12 weeks. Treatment responders from Stage A were subsequently randomly assigned to receive weekly treatment or placebo for up to 48 weeks (Stage B).

The study outcomes were clinical improvement in Stage A and efficacy of efgartigimod compared to placebo. The researchers compared the efficacy of study medication using time to clinical deterioration, which was measured as time to first adjusted Inflammatory Neuropathy Cause and Treatment (INCAT) Disability Score deterioration. 

Of 322 participants enrolled in Stage A, 221 were randomly assigned in Stage B to receive efgartigimod (n=111) or placebo (n=110). Of the participants in Stage A, 214 (66.5%) responded to treatment (95% CI, 61.0%-71.6%). The risk for clinical deterioration was significantly decreased among patients who received efgartigimod compared to those who received placebo (hazard ratio [HR], 0.394; 95% CI, 0.25-0.61; P =.000039) in Stage B.

Patients on corticosteroids, intravenous or subcutaneous immunoglobulin, or who were treatment naïve prior to the study vs patients who were not, reported a decreased risk for clinical deterioration. A total of 3 deaths unrelated to treatment occurred in this study and most treatment-emergent adverse effects were mild to moderate.

“CIDP patients treated with efgartigimod PH20 maintained a clinical response to treatment and remained relapse-free longer than those treated with placebo,” the researchers concluded.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.