Efgartigimod, the antibody treatment being developed by argenx SE for a spectrum of autoimmune diseases leapt, over another hurdle on 17 August with news that it had met the primary endpoint in a trial of two rare muscle diseases. The Phase 3 study showed that the antibody fragment, in combination with hyaluronidase enzymes, was able to restore the strength and muscle function in patients with two types of myositis: immune-mediated necrotising myopathy (IMNM) and dermatomyositis (DM). Both diseases cause muscle weakness leading potentially to long-term disability. Current treatments are limited to corticosteroids and broad immunosuppressants, which themselves are associated with cumulative toxicities, according to the company.
Efgartigimod is an antibody fragment derived from the llama and directed against the neonatal Fc receptor (FcRN). This is a protein that is widely distributed across the body and recycles immunoglobuline G. By blocking IgG recycling, efgartigimod accelerates the clearance of circulating IgG, including pathogenic antibodies. Efgartigimod is being studied in seven clinical trials. The same product, known commercially as Vyvgard, has received four regulatory approvals. The newest disease targets, IMNM and DM, are both subsets of myositis. “For people living with myositis, the goal is straightforward: regain strength and function and get off long-term steroids,” said Rohit Aggarwal, a professor of medicine at the University of Pittsburgh and a trial investigator.
The Phase 3 trial enrolled 264 patients who were randomised to receive the drug or a placebo. It was conducted in two phases over a period of 52 weeks. During the trial, patients treated with efgartigimod consistently showed improvements compared with those on the placebo.
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