Impact of Subcutaneous Efgartigimod PH20 on Treatment-naïve Participants With Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP) in the ADHERE Trial: Post Hoc Analyses
Jeffrey Allen1, Hans Katzberg2, Kelly Gwathmey3, Ken-ichi Kaida4, Satoshi Kuwabara5, Yessar Hussain6, Arne De Roeck7, Benjamin Van Hoorick7, Geoffrey Istas7, Richard Lewis8
1University of Minnesota, 2Ottawa Hospital Research Institute, 3Virginia Commonwealth University, 4Saitama Medical Center, Saitama Medical University, 5Graduate School of Medicine, Chiba University, 6Austin Neuromuscular Center, 7argenx, 8Cedars-Sinai Medical Center
Objective:

To assess the efficacy of subcutaneous (SC) efgartigimod PH20 among participants in ADHERE with a time since CIDP diagnosis of <1 year and who had never received CIDP treatment (CIDP treatment-naïve).

Background:

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

Design/Methods:

Participants with active CIDP received weekly efgartigimod PH20 SC 1000 mg (stage-A) for ≤12 weeks. Those with confirmed evidence of clinical improvement (ECI) entered stage-B and were randomized (1:1) to weekly efgartigimod PH20 SC or placebo for ≤48 weeks. Participants with clinical deterioration in stage-B or who completed ADHERE could enter ADHERE+. Primary endpoint of ADHERE stage-A was percentage of participants with ECI. Changes from stage-A baseline to stage-A last assessment in adjusted Inflammatory Neuropathy Cause and Treatment (aINCAT), Inflammatory Rasch-built Overall Disability Scale (I-RODS), and grip strength scores were assessed. Outcomes in CIDP treatment-naïve participants are reported.

Results:

Of the 322 participants enrolled in ADHERE, 24 were treatment naïve. During stage-A (≤Week 12), 87.5% (21/24) of treatment-naïve participants had confirmed ECI, compared with 64.8% (193/298) across the remaining ADHERE population; time to initial confirmed ECI (50th percentile) among treatment-naïve participants was 39.5 (95% CI, 22.0–57.0) days. Improvements exceeding the minimal clinically important difference were reported from stage-A baseline to stage-A last assessment across mean aINCAT (mean [SE] change –1.0 [0.22]), I-RODS (10.7 [2.55]), and dominant hand grip strength (15.3 [3.93]) scores in treatment-naïve participants.

Conclusions:

Efgartigimod PH20 SC treatment demonstrated a high level of response rate with quick onset of response in CIDP treatment-naïve participants. These findings address the evidence gap for treatment-naïve patients, an underrepresented population in CIDP research.

10.1212/WNL.0000000000215920
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