A Study to Assess the Effect of Empasiprubart on Nerve Morphology by Ultrasound in Adults With Multifocal Motor Neuropathy (EmpaSound)

An Open-Label, Single-Arm, Phase 1b Study to Evaluate the Effect of Empasiprubart on Nerve Morphology by Ultrasound in Adults With Multifocal Motor Neuropathy

The main purpose of the study is to evaluate empasiprubart use in adults living with Multifocal Motor Neuropathy (MMN). The researchers will evaluate the effect of empasiprubart on the thickness of the nerves, muscle strength, movement, and on the potential improvement of grip strength of the participants in handling objects.

The study consists of an open-label treatment period where all participants will receive empasiprubart intravenously (IV). After the last dose of empasiprubart participants will enter a safety follow-up period for up to 15 months.

The total study duration for each participant will be approximately 29 months.

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

Study Overview

• Status: Not yet recruiting
• Conditions: Multifocal Motor Neuropathy (MMN)
• Intervention / Treatment: Biological: Empasiprubart IV

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Sabine Coppieters, MD; Phone Number: 857-350-4834; Email: clinicaltrials@argenx.com

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Is at least 18 years old
• Diagnosed with MMN
• Has an MMN-RODS centile score of ≤90
• Has confirmed nerve thickening in at least 1 nerve per ultrasound measurement

Exclusion Criteria:

• Besides the indication under study, known autoimmune disease or any medical condition that, in the investigator's opinion, would interfere with an accurate assessment of clinical symptoms of MMN or puts the participant at undue risk.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Empasiprubart IV; Participants receive empasiprubart IV	Biological: Empasiprubart IV; Intravenous infusions of empasiprubart

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in nerve CSA at week 24 as measured by ultrasound imaging of the median nerve and brachial plexus (individual nerves and average sum score)	CSA : cross-sectional area	Up to 48 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in GS in both hands over time	The grip strength (GS) will be measured using a vigorimeter	Up to 48 weeks
Change from baseline in MMN-RODS over time	The MMN Rasch-Built Overall Disability Scale (MMN-RODS) is a disease-specific patient-reported outcome instrument that captures activity limitations in patients with MMN. The total raw score will be transformed to a centile score, ranging from 0 (worst outcome) to 100 (best outcome)	Up to 48 weeks
Change from baseline in mMRC-14 sum score over time	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 48 weeks
Percentage change from baseline in time to complete the 9-HPT with both hands 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 48 weeks
Change from baseline in nerve CSA over time as measured by ultrasound imaging of the median nerve and brachial plexus	CSA : cross-sectional area	Up to 48 weeks
Serum concentrations of empasiprubart over time		Up to 60 weeks
Percentage change from baseline in free C2 and total C2 over time	C2 : complement component 2	Up to 60 weeks
Incidence of AEs and AESIs	AE : adverse event ; AESI : adverse event of special interest	Up to 60 weeks
Incidence of SAEs	SAE : Serious adverse event	Up to 60 weeks

Collaborators and Investigators

• Sponsor: argenx

Publications and helpful links

Helpful Links

• Study website

Study record dates

Study Major Dates

• Study Start (Estimated): June 30, 2026
• Primary Completion (Estimated): February 1, 2028
• Study Completion (Estimated): April 1, 2030

Study Registration Dates

• First Submitted: May 20, 2026
• First Submitted That Met QC Criteria: May 20, 2026
• First Posted (Actual): May 28, 2026

Study Record Updates

• Last Update Posted (Actual): May 28, 2026
• Last Update Submitted That Met QC Criteria: May 20, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: ARGX-117-8-MMN-1001; 2026-525171-20-00 (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