A Study of Efgartigimod in Patients With IgG4-Related Disease

Key Inclusion Criteria: * Have a clinical diagnosis of IgG4-related disease that requires treatment in the opinion of the investigator * Meet the 2019 ACR/EULAR Classification Criteria for IgG4-Related Disease * Have a serum IgG4 concentration greater than or equal to 2 times the upper limit of normal at Screening * Have involvement of the lacrimal gland(s), salivary gland(s), and/or pancreas * If lacrimal and/or salivary glands are involved, it must be symptomatic, including but not limited to discomfort, pain, dryness, headache, or vision changes * If the pancreas is involved, it must be asymptomatic, diffuse enlargement without signs or symptoms of obstruction or evidence of major organ dysfunction in the opinion of the investigator * Have a prior inadequate response to, or intolerance of, glucocorticoids, or who have experienced recurrent symptoms after previous treatment with glucocorticoids * Are not receiving current treatment with immunosuppressive medications * All women must test negative for pregnancy and agree to use a reliable method of birth control Key Exclusion Criteria: * Any exclusion criteria listed in the 2019 ACR/EULAR Classification Criteria for IgG4-Related Disease * Prior treatment with an FcRn inhibitor * Have conventional synthetic disease-modifying antirheumatic drug (csDMARD) or immunosuppressive use as follows: * Treatment with glucocorticoids within 28 days prior to Baseline or planned treatment during the study * Treatment with csDM…