IIM is considered as a group of rare diseases that is characterized by common features of insidious painless, proximal skeletal muscle weakness, low endurance, and elevated serum muscle enzyme levels. Due to muscle weakness and progressive muscular atrophy, decreasing endurance, internal organ involvement (mainly given the pulmonary, gastrointestinal and cardiac manifestations) and limited therapeutic options, IIM often leads to physical disability and decreased quality of life. Nipocalimab is a fully human aglycosylated immunoglobulin G1 (IgG1) monoclonal antibody (mAb) designed to selectively bind, saturate, and block the immunoglobulin G (IgG) binding site on the endogenous neonatal fragment crystallizable receptor (FcRn) that binds, salvages, and recycles IgG into circulation or transport IgG across the placenta, following nonspecific pinocytosis into endothelial cells and cells of the reticuloendothelial system. At homeostasis, FcRn recycles IgG to maintain serum IgG levels and extend IgG half-life and also regulates immune cell inflammatory responses to IgG complexes. By targeting the IgG binding site on FcRn, nipocalimab is expected to block the binding and, hence, recycling of IgG, resulting in a decrease in circulating IgG antibody levels, including pathogenic IgG autoantibodies and alloantibodies. Therefore, nipocalimab has potential in the treatment of active IIM by decreasing pathogenic IgG antibody concentrations. The total duration of the study is up to 112 weeks, consisting of 4 study periods: a less than or equal to (<=) 6-week screening period, a 52-week double-blind period, a 48-week long term extension (LTE), and a safety follow-up 8 weeks post last administration of study intervention. Safety assessments include adverse events (AEs), serious adverse events (SAEs), adverse events of special interest (AESIs), laboratory parameters (hematology and chemistry, including lipid panel), vital signs, and physical examination.
The purpose of this study is to evaluate the efficacy and safety of Nipocalimab versus placebo in participants with active idiopathic inflammatory myopathies (IIM).