2025 American Academy of Neurology Abstract Website

Jeffrey Allen¹, Jie Lin², Mark Stettner³, Jeffrey Guptill⁴, Kelly Gwathmey⁵, Geoffrey Istas⁶, Arne De Roeck⁶, Satoshi Kuwabara⁷, Giuseppe Lauria⁸, Luis Querol⁹, Niraja Suresh¹⁰, Chafic Karam¹¹, Thomas Skripuletz¹², Simon Rinaldi¹³, Andoni Echaniz-Laguna¹⁴, Benjamin Van Hoorick⁶, Ryo Yamasaki¹⁵, Van Doorn Pieter¹⁶, Richard Lewis¹⁷
¹UMN, ²Fudan University, ³University Medicine Essen, ⁴Duke University, ⁵VCU Neuroscience, Orthopedic, and Wellness, ⁶argenx, ⁷Chiba University, ⁸Istituto Neurologico Carlo Besta, ⁹Hospital de la Santa Creu i Sant Pau, ¹⁰Lakeland Regional Medical Center, ¹¹University of Pennsylvania, ¹²Hannover Medical School, ¹³University of Oxford, ¹⁴Bicetre University Hospital, ¹⁵Kyushu University Hospital, ¹⁶Erasmus University Medical Center, ¹⁷Cedars-Sinai Medical Center

Objective:

Assess the efficacy of subcutaneous (SC) efgartigimod PH20 (co-formulated with recombinant human hyaluronidase PH20) in chronic inflammatory demyelinating polyneuropathy (CIDP) in ADHERE+ (Interim analysis, data cutoff: February 16, 2024).

Background:

Efgartigimod, a human immunoglobulin (Ig)G1 antibody Fc fragment, blocks the neonatal Fc receptor, decreasing IgG recycling and reducing IgGs that may play a role in CIDP pathophysiology. The multi-stage, double-blinded, placebo-controlled ADHERE (NCT04281472) and open-label extension ADHERE+ (NCT04280718) trials assessed the efficacy and safety of efgartigimod PH20 SC in participants with CIDP.

Design/Methods:

Enrolled participants had CIDP (off treatment or on standard treatments withdrawn during ≤12-week run-in). Participants with active disease received open-label, weekly efgartigimod PH20 SC 1000 mg (stage-A). Responders were randomized (1:1) to weekly efgartigimod PH20 SC 1000 mg or placebo for ≤48 weeks (stage-B). Participants with clinical deterioration in stage-B or who completed ADHERE could enter ADHERE+ (weekly efgartigimod PH20 SC 1000 mg). Changes from run-in baseline (CFB) (study enrollment) in adjusted Inflammatory Neuropathy Cause and Treatment (aINCAT), Inflammatory Rasch-built Overall Disability Scale (I-RODS) (centile metric), and (dominant hand) grip strength scores to ADHERE+ Week 36 in all enrolled participants are reported.

Results:

322 participants entered stage-A; 221 were randomized and treated in stage-B (111 efgartigimod, 110 placebo). 99% of eligible participants entered ADHERE+. Mean (SE) aINCAT, I-RODS, and grip strength scores were 4.0 (0.10), 47.9 (1.05), and 46.6 (1.75), respectively, at ADHERE run-in baseline (N=191). Mean CFB (SE) in aINCAT, I-RODS, and grip strength scores were −1.2 (0.15) and 8.8 (1.46) points and 17.5 (2.02) kPa, respectively, at ADHERE+ Week 36 (N=150), representing clinically meaningful improvements. Additionally, half of the participants who experienced clinical deterioration (aINCAT) during ADHERE stage-B restabilized on efgartigimod PH20 SC as early as ADHERE+ Week 4.

Conclusions:

Interim results from ADHERE+ indicate long-term effectiveness of efgartigimod PH20 SC in clinical outcomes in participants with CIDP.