A Study of Efgartigimod PH20 SC in Children Between 2 and Less Than 18 Years of Age With Generalized Myasthenia Gravis (ADAPT Jr SC)

June 2, 2026 updated by: argenx

An Open-label, Uncontrolled Study to Evaluate the Pharmacokinetics, Pharmacodynamics, Safety, and Activity of Efgartigimod PH20 SC in Participants From 2 to Less Than 18 Years of Age With Generalized Myasthenia Gravis

The purpose of this study is to measure the pharmacokinetics (PK), pharmacodynamics (PD), safety, tolerability, and immunogenicity of efgartigimod PH20 SC in pediatric participants with gMG aged 2 to <18 years. The primary goal is to confirm an appropriate dose of efgartigimod PH20 SC for pediatric patients using PK and PD results from this study. Participants will receive injections of efgartigimod PH20 SC and will be monitored for safety until the end of the study. At the end of the follow-up period, eligible participants may roll over to an open-label extension (OLE) study.

The participants will be in the study for up to 14 weeks.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

12

Phase

  • Phase 2
  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Australia
      • Randwich, Australia
        • Recruiting
        • Sydney Children's Hospital
        • Contact:
  • Belgium
  • Canada
      • Ottawa, Canada, K1H 8L1
        • Recruiting
        • Childrens Hospital of Eastern Ontario
        • Contact:
  • Czechia
      • Brno, Czechia, 613 00
        • Recruiting
        • Fakultni nemocnice Brno
        • Contact:
      • Ostrava, Czechia, 708 00
        • Recruiting
        • Fakultni Nemocnice Ostrava
        • Contact:
  • France
      • Marseille, France, 13385
        • Recruiting
        • AP-HM- Hôpital de La Timone
        • Contact:
  • Germany
      • Essen, Germany, 45147
  • Israel
      • Jerusalem, Israel, 9112001
        • Recruiting
        • Hadassah Medical Center- Ein Kerem
        • Contact:
      • Petah Tikvah, Israel, 4920235
        • Recruiting
        • Schneider Children's Medical Center of Israel
        • Contact:
      • Tel Aviv, Israel, 6423906
        • Recruiting
        • Tel Aviv Sourasky Medical Center Ichilov
        • Contact:
  • Italy
      • Genova, Italy, 16147
        • Recruiting
        • Istituto G Gaslini Ospedale Pediatrico IRCCS
        • Contact:
  • Netherlands
      • Leiden, Netherlands, 2333 ZA
        • Recruiting
        • Leiden University Medical Center
        • Contact:
  • Poland
      • Gdansk, Poland, 80-211
        • Recruiting
        • Uniwersyteckie Centrum Kliniczne w Gdansku
        • Contact:
      • Katowice, Poland, 40-689
        • Recruiting
        • Neurologia Śląska Centrum Medyczne
        • Contact:
      • Warsaw, Poland, 02-097
        • Recruiting
        • Centralny Szpital Kliniczny - Uniwersyteckie Centrum Kliniczne WUM
        • Contact:
  • Spain
      • Valencia, Spain, 46026
        • Recruiting
        • Hospital Universitari i Politecnic La Fe de Valencia
        • Contact:
  • Switzerland
      • Lausanne, Switzerland, 1011
  • United Kingdom
      • Oxford, United Kingdom, OX3 9DU
        • Recruiting
        • Oxford Children's Hospital
        • Contact:
  • United States
    • North Carolina
      • Charlotte, North Carolina, United States, 28207
        • Recruiting
        • Carolinas HealthCare System Neurosciences Institute - Neurology
        • Contact:
    • Texas
      • Denton, Texas, United States, 76208
        • Recruiting
        • Neurology Rare Disease Center
        • Contact:
    • Virginia
      • Charlottesville, Virginia, United States, 22903

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • The participant (and/or their legally authorized representative) understands the requirements of the study and is capable of providing written informed consent/assent and complying with protocol requirements
  • The participant is aged 2 to <18 years at the time of informed consent/assent
  • The participant has been diagnosed with generalised Myasthenia Gravis that is supported by a physical examination and confirmed seropositivity for anti-acetylcholine receptor antibodies
  • The participant has had an unsatisfactory response to immunosuppressants, corticosteroids, or acetylcholinesterase inhibitors but is on stable concomitant MG therapy. If receiving corticosteroids and/or immunosuppressants, must be on a stable dose for ≥1 month before screening
  • The participant agrees to use birth control consistent with local regulations and people of child-bearing potential must have a negative blood pregnancy test at screening and a negative urine pregnancy test before receiving the study drug

Exclusion Criteria:

  • Is a female adolescent of child-bearing potential who is pregnant and/or lactating or intends to become pregnant during their participation in the study
  • Has worsening muscle weakness secondary to a concurrent infection or as a result of a medication
  • Has a documented lack of clinical response to plasma exchange (PLEX)
  • Received a live or live-attenuated vaccine within <4 weeks before screening
  • Received a thymectomy within 3 months before screening or is planning to get a thymectomy during their participation in the study
  • Has a known autoimmune disease or any medical condition that would interfere with an accurate assessment of clinical symptoms of generalised Myasthenia Gravis or puts the participant at undue risk
  • History of malignancy, cancer, unless considered cured by adequate treatment with no evidence of recurrence for ≥3 years. Adequately treated participants with the following cancers can be included at any time: Basal cell or squamous cell skin cancer, Carcinoma in situ of the cervix, Carcinoma in situ of the breast, Incidental histological findings of prostate cancer
  • Clinically significant active infection that is not sufficiently resolved in the investigator's opinion or positive serum test at screening for active infection with any of the following: Hepatitis B virus (HBV), Hepatitis C virus (HCV), HIV
  • Has a positive PCR test for SARS-CoV-2 at screening
  • Has/had a clinically significant disease, had recent major surgery (within 3 months of screening) or intends to have major surgery during the study, or has/had any other medical condition that, in the investigator's opinion, would confound the results of the study or put the participant at undue risk
  • Has received a different study drug in another clinical study within <12 before screening
  • Is currently participating in another interventional clinical study
  • Has previously participated in an efgartigimod clinical study and received at least one dose of study drug
  • Has a known hypersensitivity to study drug or any of its excipients
  • Has a history of or current episode of alcohol, drug, or medication abuse as assessed by the investigator
  • Use of some medications before screening (more information is found in the protocol)

The complete list of exclusion criteria can be found in the protocol.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Efgartigimod PH20 SC
Participants aged 12 to <18 years receiving efgartigimod PH20 SC treatment
Biological: Efgartigimod PH20 SC
Subcutaneous injections

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Efgartigimod serum concentrations as input for compartmental, model-driven analysis to determine age and size dependency of Clearance (CL)
Time Frame: Up to 12 weeks
Up to 12 weeks
Efgartigimod serum concentrations as input for compartmental, model-driven analysis to determine age and size dependency of Volume Distribution (Vd)
Time Frame: Up to 12 weeks
Up to 12 weeks
Total G immunoglobulins (IgG) levels as input for pharmacokinetics (PK)/pharmacodynamics (PD) modelling analysis
Time Frame: Up to 12 weeks
Up to 12 weeks
Anti-acetylcholine receptors antibodies (AChR-Ab) as input for pharmacokinetics (PK)/ pharmacodynamics (PD) modelling analysis
Time Frame: Up to 12 weeks
Up to 12 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Incidence of adverse events (AEs)
Time Frame: Up to 14 weeks
Up to 14 weeks
Severity of adverse events (AEs)
Time Frame: Up to 14 weeks
Up to 14 weeks
Incidence of serious adverse events (SAEs)
Time Frame: Up to 14 weeks
Up to 14 weeks
Severity of serious adverse events (SAEs)
Time Frame: Up to 14 weeks
Up to 14 weeks
Incidence of adverse events of special interest (AESI)
Time Frame: Up to 14 weeks
Up to 14 weeks
Severity of adverse events of special interest (AESI)
Time Frame: Up to 14 weeks
Up to 14 weeks
Efgartigimod serum concentrations
Time Frame: Up to 12 weeks
Up to 12 weeks
Absolute values of total Immunoglobulin G (IgG) from blood samples
Time Frame: Up to 12 weeks
Up to 12 weeks
Change from baseline values of total Immunoglobulin G (IgG) from blood samples
Time Frame: Up to 12 weeks
Up to 12 weeks
Percentage change from baseline values of total Immunoglobulin G (IgG) from blood samples
Time Frame: Up to 12 weeks
Up to 12 weeks
Absolute values of anti-acetylcholine receptor antibodies (AChR-Ab) from blood samples
Time Frame: Up to 12 weeks
Up to 12 weeks
Change from baseline values of anti-acetylcholine receptor antibodies (AChR-Ab) from blood samples
Time Frame: Up to 12 weeks
Up to 12 weeks
Percentage change from baseline values of anti-acetylcholine receptor antibodies (AChR-Ab) from blood samples
Time Frame: Up to 12 weeks
Up to 12 weeks
Incidence of anti-drug antibodies (ADAs) against efgartigimod in serum samples
Time Frame: Up to 12 weeks
Up to 12 weeks
Prevalence of anti-drug antibodies (ADAs) against efgartigimod in serum samples
Time Frame: Up to 12 weeks
Up to 12 weeks
Incidence of antibodies against rHuPH20 in serum samples
Time Frame: Up to 12 weeks
Up to 12 weeks
Prevalence of antibodies against rHuPH20 in serum samples
Time Frame: Up to 12 weeks
Up to 12 weeks
Absolute value of total Myasthenia Gravis Activity of Daily Living (MG-ADL) score, appropriate for pediatric use
Time Frame: Up to 12 weeks
Minimum value: 0 (no impairment); Maximum value: 24 (highest impairment)
Up to 12 weeks
Change from baseline of total Myasthenia Gravis Activity of Daily Living (MG-ADL) score, appropriate for pediatric use
Time Frame: Up to 12 weeks
Minimum value: 0 (no impairment); Maximum value: 24 (highest impairment)
Up to 12 weeks
Absolute value of Quantitative Myasthenia Gravis (QMG) score
Time Frame: Up to 12 weeks
Minimum value: 0 (no impairment); Maximum value: 39 (most severe impairment)
Up to 12 weeks
Change from baseline of Quantitative Myasthenia Gravis (QMG) score
Time Frame: Up to 12 weeks
Minimum value: 0 (no impairment); Maximum value: 39 (most severe impairment)
Up to 12 weeks
Absolute value of EuroQoL 5 Dimensions Youth (EQ-5D-Y) score
Time Frame: Up to 12 weeks
Up to 12 weeks
Change from baseline value of EuroQoL 5 Dimensions Youth (EQ-5D-Y) score
Time Frame: Up to 12 weeks
Up to 12 weeks
Change from baseline value of Neuro-QoL Pediatric Fatigue Score
Time Frame: Up to 12 weeks
Up to 12 weeks
Change from baseline value of Clinical Global Impression of Improvement (CGI-I)
Time Frame: Up to 12 weeks
Up to 12 weeks
Changes in protective antibody titers to vaccines
Time Frame: Up to 12 weeks
Up to 12 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

argenx

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

June 28, 2024

Primary Completion (Estimated)

September 30, 2026

Study Completion (Estimated)

September 30, 2026

Study Registration Dates

First Submitted

April 26, 2024

First Submitted That Met QC Criteria

April 26, 2024

First Posted (Actual)

April 30, 2024

Study Record Updates

Last Update Posted (Actual)

June 3, 2026

Last Update Submitted That Met QC Criteria

June 2, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ARGX-113-2207
  • 2023-506159-12-00 (Ctis)

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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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