A Phase 3 Study to Evaluate the Efficacy and Safety of Efgartigimod IV in Patients With Acetylcholine Receptor Binding Antibody Seronegative Generalized Myasthenia Gravis

Phase 3

Active, not recruiting

• Conditions: Generalized Myasthenia Gravis
• Interventions: Biological: Efgartigimod IV; Other: Placebo IV

• Registration Number: NCT06298552
• Lead Sponsor: argenx

Brief Summary

The primary purpose of this study is to measure the efficacy and safety of efgartigimod IV compared to placebo in participants with Acetylcholine Receptor Binding Antibody (AChR-Ab) seronegative Generalized Myasthenia Gravis (gMG). The study consists of a Part A where participants will be randomized to receive either efgartigimod IV or placebo IV and a Part B where participants completing part A will receive open-label efgartigimod IV. Participants will be in the study for up to (approximately) 2.5 years.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2024-03-01
• Study First Submitted QC: 2024-03-01
• Study First Posted: 2024-03-07
• Study Start: 2024-04-16
• Status Verified: 2025-06
• Last Update Submitted: 2025-06-11
• Last Update Posted: 2025-06-13
• Primary Completion: 2025-07-25
• Study Completion: 2027-07-23

Recruitment & Eligibility

• Status: ACTIVE_NOT_RECRUITING
• Sex: All
• Target Recruitment: 119

Inclusion Criteria

• The participant is at least 18 years of age and the local legal age of consent for clinical studies when signing the ICF.

• The participant is capable of providing signed informed consent and following with protocol requirements.

• The participant agrees to use contraceptive measures consistent with local regulations and the women of child-bearing potential (WOCBP) must have a negative serum pregnancy test result at screening and a negative urine pregnancy test result at baseline before receiving the study drug.

• The participant has no known weakness in infancy and later develop fatigable weakness after aged 16 years and diagnosed with acquired gMG of both of the following:

  1. History of abnormal neuromuscular transmission demonstrated by single fiber electromyography or repetitive nerve stimulation (RNS) or is anti-muscle-specific kinase antibodies (MuSK-Ab) seropositive
  2. Either a history of positive edrophonium chloride test OR a demonstrated improvement in MG signs with treatments such as oral acetylcholinesterase (AChE) inhibitors, plasma exchange (PLEX), immunoabsorption, or intravenous immunoglobulin (IVIg)/ subcutaneous immunoglobulin (SCIg) treatment

• The participant is receiving a stable dose of MG therapy before screening that includes acetylcholinesterase (AChE) inhibitors, steroids, or nonsteroidal immunosuppressive therapies (NSISTs) in combination or alone.

Exclusion Criteria

• Known autoimmune disease or any medical condition that would interfere with an accurate assessment of clinical symptoms of gMG 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
• History of or current alcohol, drug, or medication abuse as assessed by the investigator
• Pregnant or lactating state or intention to become pregnant during the study
• Live or live-attenuated vaccine received <4 weeks before screening
• Worsening muscle weakness secondary to concurrent infections or medications
• Received a thymectomy less than 3 months before screening or thymectomy is planned during the study

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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Placebo	Placebo IV	Patients receiving placebo during part A and receiving efgartigimod IV during part B
Efgartigimod IV	Efgartigimod IV	Patients receiving efgartigimod IV in both part A and part B
Placebo	Efgartigimod IV	Patients receiving placebo during part A and receiving efgartigimod IV during part B

Primary Outcome Measures

Name	Time	Method
Myasthenia Gravis Activities of Daily Living (MG-ADL) total score change from baseline	Up to 29 days during part A	Minimum value: 0 (normal symptoms); Maximum value: 24 (most severe symptoms)

Secondary Outcome Measures

Name	Time	Method
Quantitative myasthenia gravis (QMG) total score change from baseline	Up to 29 days during part A	Minimum value: 0 (no disease severity); Maximum value: 39 (highest disease severity)
Proportion of participants who are both MG-ADL and QMG responders	Up to 8 weeks during part A

Trial Locations

Locations (91)

HonorHealth Neurology - Bob Bove Neuroscience Institute; 🇺🇸 Scottsdale, Arizona, United States

Loma Linda University Health; 🇺🇸 Fresno, California, United States

First Choice Neurology Boca Raton; 🇺🇸 Boca Raton, Florida, United States

SFM Clinical Research LLC; 🇺🇸 Boca Raton, Florida, United States

The Neurology Institute / Healthcare Innovations Institute - Coral Springs; 🇺🇸 Coral Springs, Florida, United States

Neurology Associates PA; 🇺🇸 Maitland, Florida, United States

Desai Sethi Medical Center; 🇺🇸 Miami, Florida, United States

Medsol Clinical Research Center Inc; 🇺🇸 Port Charlotte, Florida, United States

BayCare - St. Anthony's Hospital; 🇺🇸 Saint Petersburg, Florida, United States

University of South Florida (USF) Health - Morsani Center for Advanced Healthcare; 🇺🇸 Tampa, Florida, United States

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