A Study to Assess the Efficacy and Safety of Empasiprubart Versus IVIg in Adults With Multifocal Motor Neuropathy (Empassion)

A Phase 3, Randomized, Double-Blinded, Double-Dummy Study Evaluating the Efficacy and Safety of Empasiprubart Versus Intravenous Immunoglobulin in Adults With Multifocal Motor Neuropathy

The main purpose of this study is to compare empasiprubart and IVIg in adult patients with MMN. The study consists of a double-blinded part A (empasiprubart, IVIg) and an open-label part B (empasiprubart). The maximum study duration for participants is up to 49 months.

More information can be found here: https://clinicaltrials.argenx.com/empassion

Study Overview

• Status: Active, not recruiting
• Conditions: Multifocal Motor Neuropathy (MMN); MMN
• Intervention / Treatment: Biological: Empasiprubart; Other: IVIg-placebo; Biological: IVIG (Intravenous Immunoglobulin); Other: Empasiprubart-placebo

• Study Type: Interventional
• Enrollment (Actual): 154
• Phase: Phase 3

Contacts and Locations

Study Locations

• Australia
  • Parkville, Australia, 3050
    • Royal Melbourne Hospital
  • Southport, Australia, 4215
    • Gold Coast University Hospital
  • Sydney, Australia, 2609
    • Brain and Mind Center
  • Woolloongabba, Australia, 4102
    • Princess Alexandra Hospital
• Austria
  • Vienna, Austria, 1090
    • Universitätsklinikum AKH Wien
• Belgium
  • Edegem, Belgium, 2650
    • UZ Antwerpen
  • Leuven, Belgium, 3000
    • UZ Leuven
  • Liège, Belgium, 4000
    • Hôpital de la Citadelle
• Brazil
  • Ribeirão Preto, Brazil, 14051
    • Hospital das Clinicas da Faculdade de Medicina de Ribeirao Preto
  • Rio de Janeiro, Brazil, 22620-172
    • Sociedade de Ensino Superior Estacio de Sa Ltda
  • Salvador, Brazil, 40290-000
    • Escola Bahiana de Medicina e Saude Publica
  • São Paulo, Brazil, 04038-002
    • PSEG Centro de Pesquisa Clinica
• Canada
  • Gatineau, Canada, J8Y 1W2
    • Neuro-Outaouais Clinic
  • London, Canada, N6A 5A5
    • London Health Sciences Centre
  • Vancouver, Canada, V6Z 2H2
    • St. Paul's Neurology Associates
• China
  • Shanghai, China, 200040
    • Huashan Hospital Fudan University
• Czechia
  • Brno, Czechia, 625 00
    • Fakultni Nemocnice Brno
  • Hradec Králové, Czechia, 500 05
    • Fakultni nemocnice Hradec Kralove
  • Prague, Czechia, 128 08
    • Vseobecna fakultni nemocnice v Praze
• Denmark
  • Aarhus, Denmark, 8200
    • Aarhus Universitetshospital
  • Copenhagen, Denmark, 2100
    • Rigshospitalet-Inge Lehmanns Vej 8
• France
  • Bordeaux, France, 33000
    • CHU de Bordeaux - Hôpital Pellegrin
  • Brest, France, 29609
    • CHU de Brest - Hôpital La Cavale Blanche
  • Bron, France, 69500
    • Hospices Civils de Lyon - Hôpital Pierre Wertheimer
  • Le Kremlin-Bicêtre, France, 94270
    • AP-HP - Hôpital Bicêtre
  • Lille, France, 59000
    • Hopital Roger Salengro
  • Limoges, France, 87042
    • CHU Limoges - Dupuytren 1
  • Marseille, France, 13385
    • AP-HM- Hôpital de La Timone
  • Marseille, France, 13005
    • AP-HM- Hôpital de La Timone
  • Nice, France, 6001
    • CHU de Nice-Hôpital Pasteur
  • Paris, France, 75013
    • AP-HP - Hôpital de la Pitié Salpétrière
  • Strasbourg, France, 67200
    • CHU de Strasbourg - Hôpital de Hautepierre
• Germany
  • Essen, Germany, 45147
    • Universitätsklinikum Essen
  • Göttingen, Germany, 37075
    • Universität Georg August
  • Lübeck, Germany, 23538
    • Universitatsklinikum Schleswig-Holstein - Campus Lubeck
  • Münster, Germany, 48149
    • Universitätsklinikum Münster
  • Potsdam, Germany, 14471
    • Alexianer - MVZ St. Josefs-Krankenhaus Potsdam GmbH
  • Würzburg, Germany, 97080
    • Universitätsklinikum Würzburg
• Greece
  • Chaïdári, Greece, 124 62
    • University General Hospital ''ATTIKON'' - General Hospital of West Attica H AGIA VARVARA
  • Thessaloniki, Greece, 546 36
    • AHEPA University General Hospital of Thessaloniki
• Italy
  • Florence, Italy, 50134
    • Azienda Ospedaliera Universitaria Careggi
  • Genova, Italy, 16132
    • Ospedale Policlinico San Martino IRCCS
  • Gussago, Italy, 25064
    • Fondazione Serena Onlus - Centro Clinico NeMO Brescia
  • Messina, Italy, 98124
    • Az. Ospedaliera Universitaria Policlinico G. Martino
  • Milan, Italy, 20132
    • Ospedale San Raffaele S.r.l.
  • Milan, Italy, 20133
    • Azienda Ospedaliero-Universitaria San Luigi Gonzaga
  • Roma, Italy, 00189
    • Azienda Ospedaliero-Universitaria Sant'Andrea
  • Roma, Italy, 133
    • Fondazione Ptv Policlinico Tor Vergata
  • Rozzano, Italy, 20089
    • IRCCS Istituto Clinico Humanitas
• Japan
  • Bunkyō City, Japan, 113-8431
    • Juntendo University Hospital
  • Bunkyō City, Japan, 113-8519
    • Institute of Science Tokyo Hospital
  • Chūōku, Japan, 260-8677
    • Chiba University Hospital
  • Kodaira, Japan, 187-8502
    • National Center of Neurology and Psychiatry
  • Nagoya, Japan, 4668560
    • Nagoya University Hospital
  • Ube, Japan, 755-0067
    • Yamaguchi University Hospital
  • tabashi City, Japan, 173-8606
    • Teikyo University Hospital
• Latvia
  • Riga, Latvia, LV-1002
    • Pauls Stradins Clinical University Hospital
• Lithuania
  • Kaunas, Lithuania, 50161
    • Hospital of Lithuanian University of Health Sciences Kauno klinikos
• Netherlands
  • Amsterdam, Netherlands, 1105 AZ
    • Amsterdam UMC
• Norway
  • Oslo, Norway, 0450
    • Oslo Universitetssykehus HF, Ulleval
• Poland
  • Bydgoszcz, Poland, 85-065
    • MICS Centrum Medyczne Bydgoszcz
  • Katowice, Poland, 40-689
    • Centrum Medyczne Neurologia Slaska
  • Krakow, Poland, 30-688
    • SP ZOZ Szpital Uniwersytecki w Krakowie
  • Lublin, Poland, 20--64
    • Galen Clinic -- Lublin
  • Warsaw, Poland, 02-097
    • UCK WUM, Centralny Szpital Kliniczny
• Portugal
  • Porto, Portugal, 4099-001
    • ULS de Santo António, EPE - Hospital de Santo António
• Serbia
  • Belgrade, Serbia, 11000
    • University Clinical Center of Serbia
• Slovakia
  • Bratislava, Slovakia, 821 01
    • Univerzitna nemocnica Bratislava
  • Martin, Slovakia, 036 59
    • Univerzitna nemocnica Martin
• Slovenia
  • Ljubljana, Slovenia, 1000
    • University Medical Centre Ljubljana
• Spain
  • Alicante, Spain, 03010
    • Hospital General Universitario Dr. Balmis
  • Badalona, Spain, 08916
    • Hospital Universitario Germans Trias i Pujol
  • Barcelona, Spain, 08035
    • Hospital Universitario Vall d'Hebron
  • Barcelona, Spain, 08041
    • Hospital De La Santa Creu I Sant Pau
  • Barcelona, Spain, 08907
    • Hospital Universitario de Bellvitge
  • Madrid, Spain, 28039
    • Hospital Clínico San Carlos
  • Madrid, Spain, 48013
    • Hospital Universitario de Basurto
  • Málaga, Spain, 29004
    • Hospital Quironsalud Malaga
  • San Sebastián, Spain, 8035
    • Hospital Universitario de Donostia
• Switzerland
  • Bern, Switzerland, 3010
    • Inselspital - Universitätsspital Bern
• United Kingdom
  • Glasgow, United Kingdom, G51 4TF
    • Queen Elizabeth University Hospital
  • Oxford, United Kingdom, OX3 7LE
    • John Radcliffe Hospital
  • Salford, United Kingdom, M6 8HD
    • Salford Royal Hospital
  • Sheffield, United Kingdom, S10 2JF
    • Royal Hallamshire Hospital
  • Taunton, United Kingdom, TA1 5DA
    • Musgrove Park Hospital
• United States
  • Arizona
    • Scottsdale, Arizona, United States, 85251
      • HonorHealth Neurology - Bob Bove Neuroscience Institute - Neurology
  • California
    • Pomona, California, United States, 91767
      • The Neurology Group
    • Rancho Mirage, California, United States, 92270
      • Samir Macwan, M.D., Inc.
    • San Francisco, California, United States, 94143
      • University of California San Francisco
  • Colorado
    • Aurora, Colorado, United States, 80045
      • University of Colorado - Anschutz Cancer Pavilion (Neuro Onc Clinic)
  • Connecticut
    • New Haven, Connecticut, United States, 06511
      • Yale University School of Medicine
  • District of Columbia
    • Washington D.C., District of Columbia, United States, 20010
      • Medstar Health Research Institute
  • Florida
    • Boca Raton, Florida, United States, 33486
      • EZR Research LLC
    • Coral Springs, Florida, United States, 33067
      • Healthcare Innovations Institute, LLC
    • Miami, Florida, United States, 33136
      • University of Miami Miller School of Medicine
    • Tampa, Florida, United States, 33612
      • University of South Florida
  • Illinois
    • Chicago, Illinois, United States, 60611
      • Northwestern University
  • Indiana
    • Indianapolis, Indiana, United States, 46202
      • Indiana University Health Neuroscience Center
  • Kansas
    • Fairway, Kansas, United States, 66205
      • University of Kansas Medical Center
  • Maryland
    • Columbia, Maryland, United States, 21044
      • Perelman Center for Advanced Medicine
    • Columbia, Maryland, United States, 21044
      • UC Irvine - MDA ALS and Neuromuscular Center
  • Minnesota
    • Minneapolis, Minnesota, United States, 55414
      • University of Minnesota
  • New York
    • Amherst, New York, United States, 14226
      • Dent Neurologic Institute Amherst
    • New York, New York, United States, 10032
      • Columbia University Medical Center
  • North Carolina
    • Morrisville, North Carolina, United States, 27560
      • University of North Carolina at Chapel Hill
  • Ohio
    • Cleveland, Ohio, United States, 44195
      • The Cleveland Clinic Foundation
  • Oregon
    • Portland, Oregon, United States, 97239
      • Oregon Health and Science University
  • Texas
    • Austin, Texas, United States, 78759-8402
      • National Neuromuscular Research Institute
    • Houston, Texas, United States, 77094
      • NeuroCarePlus

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Is at least 18 years of age and the local legal age of consent for clinical studies
• Has a confirmed diagnosis of definite or probable MMN at screening according to the EFNS/PNS 2010 guidelines
• Has responded to IVIg in the past 5 years.
• Is receiving IVIg at a treatment interval of once every 2, 3, 4, or 5 weeks, and a dose of 0.4 to 2.0 g/kg body weight per cycle
• Is receiving a maintenance regimen (no change in frequency, and no change in dose >10%) of IVIg for at least 8 weeks before screening (or at least 10 weeks for participants receiving IVIg once every 5 weeks)
• Minimum converted weekly IVIg dose of ≥0.125 g/kg
• Has documented immunization against encapsulated bacterial pathogens (N meningitidis and S pneumoniae) within 5 years of screening or is willing to receive immunization at least 14 days before first study drug administration

Exclusion Criteria:

• Besides the indication under study, known autoimmune disease (eg, SLE) or any other medical condition that would confound the study results or put the participant at undue risk
• Clinical signs or symptoms suggestive of neuropathies other than MMN, such as motor neuron disease (eg, bulbar signs, brisk reflexes) or other inflammatory neuropathies (eg, sensory neuropathy)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Part A - empasiprubart + IVIg-placebo; During the double blinded - double dummy part A, participants receive empasiprubart and a placebo resembling the IVIg treatment in this arm	Biological: Empasiprubart; Intravenous infusion of empasiprubart; Other: IVIg-placebo; A placebo resembling the IVIg treatment
Active Comparator: Part A - IVIg + empasiprubart-placebo; During the double blinded - double dummy part A, participants receive IVIg and a placebo resembling the empasiprubart treatment in this arm	Biological: IVIG (Intravenous Immunoglobulin); Intravenous infusion of IVIg; Other: Empasiprubart-placebo; A placebo resembling the empasiprubart treatment
Experimental: Part B - empasiprubart; After completion of part A, participants can proceed to part B where they receive empasiprubart (no IVIg)	Biological: Empasiprubart; Intravenous infusion of empasiprubart

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Change from baseline in grip strength (4-week average) in the most affected hand at week 24	Up to 24 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in MMN-RODS centile score at week 24	The 25-Item Rasch-Built Overall Disability Scale for MMN (MMN-RODS) is a questionnaire about the relationship between daily activities and the participants' health	Up to 24 weeks
Change from baseline in grip strength (3-day moving average) in the most affected hand at week 24		Up to 24 weeks
Change from baseline in mMRC-14 sum score	The modified Medical Research Council (mMRC)-14 is a questionnaire where each muscle group is scored from 0 (paralysis) to 5 (normal strength). A higher value indicates better muscle strength. The total score is based on the sum of both the left and right side of the body.	Up to 24 weeks (Part A), Up to 120 weeks (Part B)
PGI-C actual value	The Patient Global Impression of Change (PGI-C) is a 7-point scale depicting a participant's rating of overall improvement. The lower the score, the better the improvement.	Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Change from baseline in CAP-PRI total score	The Chronic Acquired Polyneuropathy Patient-Reported Index (CAP-PRI) includes the assessment of 15 items. Items will be scored 0 (not at all), 1 (a little bit), or 2 (a lot), yielding a total score that ranges from 0 to 30.	Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Percentage change from baseline in time to complete the 9-HPT with the dominant hand	The 9-Hole Peg Test (9-HPT) is a quantitative measure of upper extremity (arm and hand) function. Both the dominant and nondominant hands will be tested twice (2 consecutive trials of the dominant hand, followed immediately by 2 consecutive trials of the nondominant hand).	Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Incidence of AEs, AESIs and SAEs		Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Serum concentrations over time of empasiprubart		Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Percent changes from baseline in free C2 and total C2 over time		Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Incidence of anti-drug antibodies (ADA) against empasiprubart in serum		Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Incidence of NAb against empasiprubart in serum		Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Change from baseline in grip strength (3-day moving average) of the least affected hand over time		Up to 24 weeks
AUC of change from baseline in grip strength (3-day moving average) for the most and least affected hands		Up to 24 weeks
Percentage change from baseline in time to complete the 9-HPT with the nondominant hand over time	The 9-Hole Peg Test (9-HPT) is a quantitative measure of upper extremity (arm and hand) function. Both the dominant and nondominant hands will be tested twice (2 consecutive trials of the dominant hand, followed immediately by 2 consecutive trials of the nondominant hand).	Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Change from baseline in sum scores for mMRC-10 and mMRC-14 restricted to the 2 most affected muscle groups over time	The modified Medical Research Council (mMRC) is a questionnaire where each muscle group is scored from 0 (paralysis) to 5 (normal strength). A higher value indicates better muscle strength. The total score is based on the sum of both the left and right side of the body.	Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Proportion of participants and shift from baseline over time by level of severity on PGI-S	Patient Global Impression of Severity (PGIS) is a 7-point scale depicting a participant's rating of overall illness severity. Higher scores mean a higher severity.	Up to 24 weeks
Change from baseline in Rasch-Transformed Fatigue Severity Scale (RT-FSS) score over time		Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Change from baseline in physical component and mental component scores of 12-Item Short Form Survey (SF-12) over time		Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Proportion of participants and shift from baseline by each dimension of the EQ-5D-5L scale		Up to 24 weeks (Part A), Up to 120 weeks (Part B)
Changes from baseline in grip strength (3-day moving average; both hands)		Up to 120 weeks (part B)
Actual values of PGI-S over time	Patient Global Impression of Severity (PGIS) is a 7-point scale depicting a participant's rating of overall illness severity. Higher scores mean a higher severity.	Up to 120 weeks (part B)
Changes from baseline in MMN-RODS centile score	The 25-Item Rasch-Built Overall Disability Scale for MMN (MMN-RODS) is a questionnaire about the relationship between daily activities and the participants' health	Up to 120 weeks (part B)

Collaborators and Investigators

• Sponsor: argenx

Publications and helpful links

General Publications

• Caballero-Avila M, Pascual-Goni E, Lleixa C, Martin-Aguilar L, Collet-Vidiella R, Querol L. The changing landscape of primary autoimmune neuropathies. Nat Rev Neurol. 2025 Oct;21(10):544-555. doi: 10.1038/s41582-025-01133-3. Epub 2025 Sep 5.

Helpful Links

• Study website

Study record dates

Study Major Dates

• Study Start (Actual): December 18, 2024
• Primary Completion (Estimated): September 1, 2026
• Study Completion (Estimated): December 1, 2029

Study Registration Dates

• First Submitted: December 16, 2024
• First Submitted That Met QC Criteria: December 16, 2024
• First Posted (Actual): December 19, 2024

Study Record Updates

• Last Update Posted (Actual): May 20, 2026
• Last Update Submitted That Met QC Criteria: May 18, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nervous System Diseases; Neuromuscular Diseases; Peripheral Nervous System Diseases; Neuritis; Amino Acids, Peptides, and Proteins; Proteins; Antibodies; Immunoglobulins; Immunoproteins; Blood Proteins; Serum Globulins; Globulins; Immunoglobulin Isotypes; Immunoglobulin G; Immunoglobulins, Intravenous
• Other Study ID Numbers: ARGX-117-2302; 2024-516473-72-00 (Ctis)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No