LB: Impact of Efgartigimod PH20 SC on Grip Strength in Chronic Inflammatory Demyelinating Polyradiculoneuropathy: Post Hoc Analysis of ADHERE/ADHERE+

Topic:

Clinical Trials

Poster Number: 502 LBM

Author(s):

Richard A. Lewis, MD, Cedars-Sinai Medical Center, Los Angeles, CA, USA, Kelli Musick, PharmD, argenx, Ghent, Belgium, Christian Eggers, Kepler University Hospital, Linz, Austria, Frank Leypoldt, Christian-Albrecht University of Kiel & University Medical Center Schleswig-Holstein, Kiel, Germany, Giuseppe Lauria Pinter, MD, IRCCS Foundation “Carlo Besta” Neurological Institute & University of Milan, Milan, Italy, Luis Querol, MD, PhD, Hospital de La Santa Creu I Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain, Mark Stettner, MD, PhD, University Medicine Essen, Essen, Germany, Pieter A. van Doorn, MD, PhD, Erasmus University Medical Center, Rotterdam, the Netherlands, Simon Rinaldi, MBChB, PhD, University of Oxford, Oxford, UK, Thomas Skripuletz, MD, Hannover Medical School, Hanover, Germany, Arie Gafson, argenx, Ghent, Belgium, Geoffrey Istas, PhD, argenx, Ghent, Belgium, Arne De Roeck, PhD, argenx, Ghent, Belgium, Katerina Anokhina, argenx, Ghent, Belgium, Jeffrey A. Allen, MD, University of Minnesota, Minneapolis, MN, USA

Background

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an immune-mediated neuropathy characterized by proximal and distal weakness and sensory disturbance that can lead to irreversible disability.

Objectives

Assess the effect of subcutaneous (SC) efgartigimod PH20 on grip strength in CIDP.

Methods

In ADHERE (NCT04281472), participants receiving CIDP treatment entered a ≤12-week run-in during which CIDP treatments were withdrawn to identify participants with active disease. Participants received open-label weekly efgartigimod PH20 SC 1000 mg (stage A). Responders were randomized (1:1) to efgartigimod or placebo for ≤48 weeks (stage B). Participants with clinical deterioration or who completed stage B without clinical deterioration entered ADHERE+ (NCT04280718). We report a post hoc analysis of grip strength in stage A responders from run-in baseline through ADHERE+ Week 36 (minimal clinically important difference [MCID]: ≥8 kPa).

Results

322 participants entered stage A; 221 were randomized and treated in stage B. Among participants receiving efgartigimod during stage B (n=97), mean (SE) and median dominant hand grip strength scores at run-in baseline were 44.4 kPa (2.39) and 47.0 kPa. Mean (SE) and median changes from run-in baseline to stage A last assessment (n=97), stage B last assessment (n=97), and ADHERE+ Week 36 (n=76) were 9.1 kPa (1.70) and 6.0 kPa; 12.0 kPa (2.34) and 7.0 kPa; and 18.2 kPa (2.57) and 12.5 kPa, respectively. A similar trend was noted for non-dominant grip strength scores. In participants who responded to efgartigimod treatment in stage A, mean (SE) and median changes from run-in baseline to ADHERE+ Week 36 (n=149) in dominant hand grip strength scores were 17.5 kPa (2.02) and 10.0 kPa; non-dominant hand: 17.8 kPa (2.00) and 13.0 kPa. During ADHERE+ Week 36, 50.3% (75/149) and 38.9% (58/149) of participants achieved ≥16 or ≥24 kPa improvement, respectively, in grip strength in any hand.

Conclusions

Long-term efgartigimod PH20 SC treatment improved grip strength in participants with CIDP; a 2–3 fold improvement in MCID was reported in ~40–50% of participants.