A Study to Assess the Safety of ARGX-124 in Healthy Volunteers

A Phase 1, Randomized, Double-Blinded, Placebo-Controlled Study to Investigate the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Immunogenicity of Single and Multiple Ascending Doses of ARGX-124 in Healthy Adult Participants

This study aims to assess the safety of ARGX-124 in healthy adults. Another aim is to measure the amount of ARGX-124 in the blood over time to learn how it acts and moves in the body and how the immune system responds to it. Participants will remain in the study for up to approximately 23 weeks.

Study Overview

• Status: Recruiting
• Conditions: Healthy Volunteers
• Intervention / Treatment: Biological: ARGX-124; Other: Placebo

• Study Type: Interventional
• Enrollment (Estimated): 104
• Phase: Phase 1

Contacts and Locations

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

Study Locations

• Canada
  • Montreal, Canada, H3P 3P1
    • Recruiting
    • Altasciences
    • Contact: Gaetano Morelli, MD; Phone Number: 857-350-4834; Email: clinicaltrials@argenx.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Is at least the local legal age of consent and aged 18 to 65 years, inclusive, when signing the ICF.
• Is a female of Nonchildbearing Potential (postmenopausal or surgically sterilized) or a male.
• Has a body weight between 50 and 120 kg and a BMI between 18 and 30.5 kg/m2, inclusive.

Exclusion Criteria:

• Has any current or past clinically meaningful medical or psychiatric condition that, in the investigator's opinion, would confound the study results or put the participant at undue risk.
• Has IgG levels <6.0 g/L at screening.
• Has a history of an immunosuppressive disease or an immunosuppressive condition at screening.
• Previously participated in an ARGX-124, ARGX-213, or efgartigimod clinical study and received at least 1 dose of the study drug.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo; Participants receiving placebo	Other: Placebo; Administrations of placebo comparator
Experimental: ARGX-124; Participants receiving the experimental drug	Biological: ARGX-124; Administrations of ARGX-124

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of AEs, SAEs and AEs leading to ARGX-124 discontinuation	AE : adverse event ; SAE : serious adverse event.	Up to 23 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximum observed serum concentration (Cmax)		Up to 23 weeks
Percent change from baseline in total IgG levels in serum over time	IgG : immunoglobulin G	Up to 23 weeks
Incidence of ADA against ARGX-124 in serum	ADA : anti-drug antibodies	Up to 23 weeks

Collaborators and Investigators

• Sponsor: argenx

Study record dates

Study Major Dates

• Study Start (Actual): January 26, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: January 22, 2026
• First Submitted That Met QC Criteria: January 22, 2026
• First Posted (Actual): January 29, 2026

Study Record Updates

• Last Update Posted (Actual): March 6, 2026
• Last Update Submitted That Met QC Criteria: March 4, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: ARGX-124-1-HV-1001

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: No
• Studies a U.S. FDA-regulated device product: No