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

NCT06298552 | Active Not Recruiting Phase 3 DMC FDA Drug

• 2 other identifiers: ARGX-113-23082024-511796-15-00
• Study Type: interventional
• Target: 119
• Locations: 22 countries
• Sites: 91

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.

Conditions

Generalized Myasthenia Gravis; gMG; Myasthenia Gravis, Generalized; Myasthenia Gravis

Outcome Measures

Primary Outcomes (1)

• MG-ADL total score change from baseline

  The Myasthenia Gravis Activities of Daily Living (MG- ADL) scale is an 8-item instrument used to assess MG symptoms and their effects on daily activities. The total score ranges from 0 (normal symptoms) to 24 (most severe symptoms)

  Up to 29 days (part A)

Secondary Outcomes (11)

• QMG total score change from baseline

  Up to 8 weeks (part A) + 2 years (part B)

• Proportion of participants who are both MG-ADL and QMG responders in part A

  Up to 8 weeks (part A)

• Proportion of participants with MSE

  Up to 8 weeks (part A) + 2 years (part B)

• Proportion of participants who are MG-ADL responders in part A

  Up to 8 weeks (part A)

• Proportion of participants who are QMG responders in part A

  Up to 8 weeks (part A)

Study Arms (2)

Efgartigimod IV

EXPERIMENTAL

Patients receiving efgartigimod IV in both part A and part B

Biological: Efgartigimod IV

Placebo

PLACEBO COMPARATOR

Patients receiving placebo during part A and receiving efgartigimod IV during part B

Biological: Efgartigimod IV; Other: Placebo IV

Interventions

Efgartigimod IV BIOLOGICAL

Intravenous infusion of efgartigimod

Efgartigimod IV; Placebo

Placebo IV OTHER

Intravenous infusion of placebo

Placebo

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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:
• 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
• 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.

You may not qualify if:

• 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

Sponsors & Collaborators

• argenx: lead

Study Sites (91)

HonorHealth Neurology - Bob Bove Neuroscience Institute

Scottsdale, Arizona, 85251, United States

Location

Loma Linda University Health

Fresno, California, 93701-2234, United States

Location

First Choice Neurology Boca Raton

Boca Raton, Florida, 33428, United States

Location

SFM Clinical Research LLC

Boca Raton, Florida, 33487, United States

Location

The Neurology Institute / Healthcare Innovations Institute - Coral Springs

Coral Springs, Florida, 33067, United States

Location

Neurology Associates PA

Maitland, Florida, 32751, United States

Location

Desai Sethi Medical Center

Miami, Florida, 33136, United States

Location

Medsol Clinical Research Center Inc

Port Charlotte, Florida, 33952, United States

Location

BayCare - St. Anthony's Hospital

St. Petersburg, Florida, 33705-1410, United States

Location

University of South Florida (USF) Health - Morsani Center for Advanced Healthcare

Tampa, Florida, 33612, United States

Location

Wellstar - Augusta University Medical Center

Augusta, Georgia, 30912, United States

Location

Kansas University Medical Center - Kansas City

Fairway, Kansas, 66205, United States

Location

Rutgers-Robert Wood Johnson Medical School

New Brunswick, New Jersey, 08901-1962, United States

Location

University of North Carolina - Chapel Hill

Chapel Hill, North Carolina, 27599-7025, United States

Location

Duke University School of Medicine - Duke Early Phase Clinical Research Unit

Durham, North Carolina, 27710, United States

Location

Cleveland Clinic

Cleveland, Ohio, 44195, United States

Location

Erlanger Neuroscience Institute

Chattanooga, Tennessee, 37403-2173, United States

Location

National Neuromuscular Research Institute

Austin, Texas, 78756, United States

Location

University of Washington Medical Center - Montlake

Seattle, Washington, 98195, United States

Location

Hôpital Erasme

Anderlecht, 1070, Belgium

Location

Cliniques Universitaires Saint-Luc

Brussels, 1200, Belgium

Location

AZ Sint-Lucas Gent

Ghent, 9000, Belgium

Location

UZ Leuven

Leuven, 3000, Belgium

Location

Heritage Medical Research Clinic

Calgary, T2N 4Z6, Canada

Location

Genge Partners Inc.

Montreal, H4A 3T2, Canada

Location

Ottawa Hospital - Civic Campus

Ottawa, K1H 8L6, Canada

Location

Xuanwu Hospital Capital Medical University

Beijing, 100053, China

Location

The First Hospital of Jilin University

Changchun, 130021, China

Location

Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital

Chongqing, 400016, China

Location

The First Affiliated Hospital of Chongqing Medical University

Chongqing, 400016, China

Location

Fujian Medical University Union Hospital

Fuzhou, 350001, China

Location

The First Affiliated Hospital of Guangxi Medical University

Guangxi, 530021, China

Location

The First Affiliated Hospital of Guangzhou University Chinese Medicine

Guangzhou, 510405, China

Location

Guangdong Province Traditional Chinese Medical Hospital

Guangzhou, 518053, China

Location

The Affiliated Hospital of Guizhou Medical University

Guiyang, 550004, China

Location

Ningbo Medical Center Lihuili Hospital

Ningbo, 315041, China

Location

Qilu Hospital of Shandong University

Qingdao, 266035, China

Location

Huashan Hospital Fudan University

Shanghai, 200040, China

Location

First Hospital of Shanxi Medical University

Taiyuan, 030001, China

Location

Tongji Hospital Tongji Medical College Huazhong University of Science and Technology

Wuhan, 430030, China

Location

Cyprus Institute of Neurology and Genetics

Égkomi, 2371, Cyprus

Location

Fakultni nemocnice Brno

Brno, 625 00, Czechia

Location

Nemocnice Pardubickeho kraje, a.s., Pardubicka nemocnice

Pardubice, 530 03, Czechia

Location

Aarhus Universitetshospital

Aarhus, 8200, Denmark

Location

Rigshospitalet

Copenhagen, 2100, Denmark

Location

Odense Universitetshospital

Odense C, 5000, Denmark

Location

Turun Yliopistollinen Keskussairaala

Turku, 20540, Finland

Location

AP-HM- Hôpital de La Timone

Marseille, 13386, France

Location

CHU de Nice-Hôpital Pasteur

Nice, 06000, France

Location

AP-HP - Hôpital de la Pitié Salpétrière

Paris, 75013, France

Location

West Georgia Medical Center

Kutaisi, 4600, Georgia

Location

Petre Sarajishvili Institute of Neurology

Tbilisi, 0112, Georgia

Location

Pineo Medical Ecosystem

Tbilisi, 0112, Georgia

Location

New Hospitals

Tbilisi, 0114, Georgia

Location

LLC Caucasus Medical Centre

Tbilisi, 0186, Georgia

Location

Charité - Universitätsmedizin Berlin

Berlin, 13353, Germany

Location

Katholisches Klinikum Bochum - St. Josef Hospital

Bochum, 44791, Germany

Location

Universitätsklinikum Würzburg

Würzburg, 97080, Germany

Location

Eginitio Hospital

Athens, 115 28, Greece

Location

University General Hospital ''ATTIKON''

Chaïdári, 124 62, Greece

Location

University General Hospital of Patras

Pátrai, 265 04, Greece

Location

AHEPA University General Hospital of Thessaloniki

Thessaloniki, 546 36, Greece

Location

Semmelweis Egyetem Genomikai Medicina és Ritka Betegségek Intézete

Budapest, 1082, Hungary

Location

Leiden University Medical Center

Leiden, 2333 ZA, Netherlands

Location

Universitair Medisch Centrum Utrecht

Utrecht, 3584 CX, Netherlands

Location

Haukeland Universitetssykehus

Bergen, 5021, Norway

Location

Oslo Universitetssykehus HF, Ullevål

Oslo, 424, Norway

Location

MICS Centrum Medyczne Bydgoszcz

Bydgoszcz, 85-065, Poland

Location

Centrum Medyczne Neurologia Slaska

Katowice, 40-689, Poland

Location

Szpital Uniwersytecki w Krakowie

Krakow, 31-503, Poland

Location

Krakowska Akademia Neurologii Sp. z o.o.

Krakow, 31-505, Poland

Location

CLINIREM Sp z o.o.

Lublin, 20-883, Poland

Location

Uniwersytecki Szpital Kliniczny im. Jana Mikulicza Radeckiego we Wroclawiu

Wroclaw, 50-556, Poland

Location

ULS de Santa Maria, EPE - Hospital de Santa Maria

Lisbon, 1150-199, Portugal

Location

ULS de Lisboa Ocidental, EPE - Hospital Egas Moniz

Lisbon, 1349-019, Portugal

Location

Hospital de Santo António - Unidade Local de Saúde de Santo António

Porto, 4050-011, Portugal

Location

Cluj County Emergency Clinical Hospital

Cluj-Napoca, 400012, Romania

Location

Sibiu Emergency County Clinical Hospital

Sibiu, 550166, Romania

Location

King Faisal Specialist Hospital & Research Center

Riyadh, 11211, Saudi Arabia

Location

National Guard Riyadh

Riyadh, 14611, Saudi Arabia

Location

Opsta bolnica MSB - Medicinski Sistemi Beograd

Belgrade, 11000, Serbia

Location

University Clinical Center Kragujevac

Kragujevac, 34000, Serbia

Location

Hospital General Universitario Dr. Balmis

Alicante, 03010, Spain

Location

Hospital Universitario Vall d'Hebron - PPDS

Barcelona, 8035, Spain

Location

Hospital de La Santa Creu i Sant Pau

Barcelona, 8041, Spain

Location

Hospital Universitari Arnau de Vilanova

Lleida, 25198, Spain

Location

Hospital Universitario Ramon y Cajal

Madrid, 28304, Spain

Location

Hospital Clinico Universitario de Santiago

Santiago de Compostela, 15706, Spain

Location

Hospital Universitari i Politecnic La Fe de Valencia

Valencia, 46026, Spain

Location

Panthera Biopartners

Glasgow, G51 4TY, United Kingdom

Location

Leeds General Infirmary

Leeds, LS1 3EX, United Kingdom

Location

Related Links

• US patient website
• US HCP website

MeSH Terms

Conditions

Myasthenia Gravis

Condition Hierarchy (Ancestors)

Paraneoplastic Syndromes, Nervous System; Nervous System Neoplasms; Neoplasms by Site; Neoplasms; Paraneoplastic Syndromes; Autoimmune Diseases of the Nervous System; Nervous System Diseases; Neurodegenerative Diseases; Neuromuscular Junction Diseases; Neuromuscular Diseases; Autoimmune Diseases; Immune System Diseases

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: March 1, 2024
• First Posted: March 7, 2024
• Study Start: April 16, 2024
• Primary Completion: June 30, 2025
• Study Completion (Estimated): June 1, 2027
• Last Updated: November 5, 2025

Record last verified: 2025-11

Locations

GE (5); CN (14); CZ (2); FI (1); NO (2); ES (7); US (19); BE (4); HU (1); SE (2); RO (2); PT (3); CA (3); NL (2); FR (3); SA (2); GR (4); GB (2); PL (6); CY (1); DE (3); DK (3)