A Study to Investigate the Efficacy and Safety of Efgartigimod PH20 SC in Adult Participants With Active Idiopathic Inflammatory Myopathy.

Completed · Phase 2/Phase 3 · Has a placebo group

Conditions studied: Active Idiopathic Inflammatory Myopathy, Myositis, Dermatomyositis, Polymyositis, Immune-Mediated Necrotizing Myopathy, Antisynthetase Syndrome

In brief

This study's purpose is to measure the treatment response from efgartigimod PH20 SC compared with placebo in participants with Idiopathic Inflammatory Myopathy (IIM). Participants with the IIM subtypes of dermatomyositis (DM), immune-mediated necrotizing myopathy (IMNM), or certain other subtypes of polymyositis (PM; including antisynthetase syndrome \[ASyS\]) will be included in the study. Treatment response will be measured by Total improvement score (TIS).

Key facts

Study ID

NCT05523167

Run by

argenx

People needed

265

Starts

2022-10-12

Expected to finish

2026-07-02

Last updated by the study team

2026-07-24

Who can join

Age: 18 and older. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• Ability to consent in the jurisdiction in which the study is taking place and capable of giving signed informed consent.
• A definite or probable clinical diagnosis of idiopathic inflammatory myopathy (IIM)
• One of the following medical histories: Diagnosis of dermatomyositis (DM) or juvenile dermatomyositis (JDM), Diagnosis of polymyositis (PM) (including antisynthetase syndrome (ASyS)), Diagnosis of immune-mediated necrotizing myopathy (IMNM)
• Diagnosed with active disease as defined by the presence of at least 1 of the following criteria: Abnormal levels of at least 1 of the following enzymes: creatine kinase (CK), aldolase, lactate dehydrogenase, aspartate aminotransaminase (AST), alanine aminotransferase (ALT), based on central laboratory results; Electromyography demonstrating active disease within the past 3 months; Active dermatomyositis (DM) skin rash; Muscle biopsy indicative of active idiopathic inflammatory myopathy (IIM) in the past 3 months; Magnetic resonance imaging within the past 3 months indicative of active inflammation
• Muscle weakness
• Receiving a permitted background treatment for idiopathic inflammatory myopathy.
• Contraceptive use consistent with local regulations, where available, for individuals participating in clinical studies. Women of childbearing potential must have a negative serum pregnancy test during screening and a negative urine pregnancy test at baseline before receiving investigational medicinal product (IMP).

You may not qualify if…

• Any other known autoimmune disease that, in the investigator's opinion, would interfere with an accurate assessment of clinical symptoms of idiopathic inflammatory myopathy (IIM) or put the patient at undue risk
• A history of malignancy unless considered cured by adequate treatment, with no evidence of recurrence for ≥ 3 years before the first administration of the investigational medicinal product (IMP). 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 finding of prostate cancer
• Severe muscle damage
• Glucocorticoid-induced myopathy that the investigator considers the primary cause of muscle weakness or permanent weakness linked to a non-idiopathic inflammatory myopathy (IIM) cause
• Uncontrolled interstitial lung disease or any other uncontrolled idiopathic inflammatory myopathy (IIM) manifestation that, in the opinion of the investigator, would be likely to require treatment with prohibited medication during the study
• Participant is pregnant or lactating or intends to become pregnant during the study.

Where it is running

• HonorHealth Neurology - Bob Bove Neuroscience Institute - Neurology — Scottsdale, Arizona, United States
• Attune Health Research, Inc — Beverly Hills, California, United States
• University of Southern California Norris Comprehensive Cancer Center — Los Angeles, California, United States
• Profound Research LLC - Oceanside — Oceanside, California, United States
• University of California, Irvine — Orange, California, United States
• Eisenhower Medical Center — Rancho Mirage, California, United States
• Stanford Medicine Outpatient Center - Stanford Dermatology Clinic-Stanford University School of Medicine — Redwood City, California, United States
• California Pacific Medical Center - Sutter Health — San Francisco, California, United States
• Amyotrophic Lateral Sclerosis (ALS) Treatment Center,University of California San Francisco (UCSF) — San Francisco, California, United States
• Denver Arthritis Clinic — Denver, Colorado, United States
• Yale Cancer Center-Yale University School Of Medicine — New Haven, Connecticut, United States
• Georgetown University Hospital — Washington D.C., District of Columbia, United States
• UF Health Rheumatology — Gainesville, Florida, United States
• Mayo Clinic — Jacksonville, Florida, United States
• University of South Florida (USF) - Morsani Center (USF Health Carol and Frank Morsani Center for Advanced Healthcare) — Tampa, Florida, United States
• Emory University Hospital, The Emory Clinic — Atlanta, Georgia, United States
• Augusta University — Augusta, Georgia, United States
• Northwestern Memorial Hospital — Chicago, Illinois, United States
• University Of Kansas Medical Center — Kansas City, Kansas, United States
• Johns Hopkins Medicine - Johns Hopkins Myositis Center — Baltimore, Maryland, United States
• Harvard Medical School - Brigham and Women's Hospital (BWH) - The Schuster Family Transplantation Research Center (TRC) — Boston, Massachusetts, United States
• Michigan State University - Neurology — East Lansing, Michigan, United States
• St. Paul Rheumatology, PA — Saint Paul, Minnesota, United States
• Washington University School of Medicine — St Louis, Missouri, United States
• Neuromuscular Research Center — Phoenix, Arizona, United States

Full record on ClinicalTrials.gov

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