A Randomized, Double-Blinded, Placebo-Controlled, Phase 3, Parallel-Group Design Study Evaluating the Efficacy and Safety of Efgartigimod IV in Adult Participants With Acetylcholine Receptor Binding Antibody Seronegative Generalized Myasthenia Gravis

ARGX-113-2308

The primary purpose of this study is to measure the efficacy and safety of efgartigimod intravenously (IV) compared to placebo in participants with Acetylcholine Receptor Binding Antibody (AChR-Ab) seronegative Generalized Myasthenia Gravis (gMG). Other objectives are to assess long-term efficacy, safety, and tolerability of efgartigimod. Study will consist of: * Screening * Part A: participants will be randomized to receive either efgartigimod IV or placebo * Part B: participants completing part A will receive open-label efgartigimod IV

2024-04-16

2025-07-25

2027-07-23

Recruiting

Early phase I

110

Inclusion Criteria: * The participant is at least 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 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 * Current participation in another interventional clinical study or previous participation in an efgartigimod clinical study and received at least 1 dose of the study drug * Known hypersensitivity to study drug or one of its excipients (inactive ingredients) * 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 * 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.

{'studyType': 'INTERVENTIONAL', 'phases': ['PHASE3'], 'designInfo': {'allocation': 'RANDOMIZED', 'interventionModel': 'PARALLEL', 'primaryPurpose': 'TREATMENT', 'maskingInfo': {'masking': 'DOUBLE', 'whoMasked': ['PARTICIPANT', 'INVESTIGATOR']}}, 'enrollmentInfo': {'count': 110, 'type': 'ESTIMATED'}}

2024-05-22