Vyvgart Clears Antibody-Subtype Hurdle as argenx Approaches Readouts from Two Pivotal Autoimmune Trials

Autoantibody test results could previously determine whether patients with generalized myasthenia gravis were eligible for certain targeted therapies. argenx said that following the U.S. indication expansion for Vyvgart and its subcutaneous formulation, Vyvgart Hytrulo, the treatments now cover all serotypes of generalized myasthenia gravis in adults, including patients who are positive for anti-AChR, anti-MuSK, or anti-LRP4 antibodies, as well as those who are negative for all three, meaning serological classification is no longer a labeling hurdle for use of the drug.

Vyvgart’s active ingredient, efgartigimod, is an antibody fragment that binds to the neonatal Fc receptor (FcRn). FcRn normally helps IgG antibodies avoid degradation; blocking this recycling pathway can reduce circulating IgG, including potentially pathogenic autoantibodies. The indication expansion increases the treatable population, but does not mean efficacy is identical across patients with different serotypes. Actual responses and risks must still be interpreted according to the clinical data supporting the label.

The update also shows that argenx is translating commercial success into a broader clinical portfolio. The company reported global net product sales of $1.516 billion for the Vyvgart franchise in the second quarter of 2026, an increase of 60% from the same period last year, while continuing to test efgartigimod’s potential in autoimmune diseases including myositis, primary immune thrombocytopenia, Sjögren’s disease, and Graves’ disease.

The first near-term pivotal milestone is the ALKIVIA trial. ClinicalTrials.gov data show that this is a randomized, double-blind, placebo-controlled Phase 2/3 trial involving approximately 265 adults, evaluating subcutaneous efgartigimod in active idiopathic inflammatory myopathy. It includes dermatomyositis, immune-mediated necrotizing myopathy, and eligible polymyositis subtypes, including antisynthetase syndrome. argenx expects to announce topline results in the third quarter of 2026; if the trial meets its endpoint, it would provide important validation for Vyvgart’s expansion into rheumatology and immunology.

Another readout will come from empasiprubart. This antibody targets complement component C2 and has a different mechanism of action from the FcRn inhibitor efgartigimod. The Phase 3 EMPASSION trial uses a double-blind, double-dummy design to directly compare empasiprubart with intravenous immunoglobulin for the treatment of multifocal motor neuropathy. The trial registry shows that 154 participants were actually enrolled, with primary completion estimated for September 2026, broadly aligning with the company’s guidance that preliminary results will be announced in the fourth quarter.

However, what has been announced so far consists of label and timeline updates, not efficacy or safety answers from these two registered trials. Trial completion, database lock, and the release of results may also occur at different times. argenx also expects a readout in the first half of 2027 from the ADVANCE-NEXT trial of efgartigimod in primary immune thrombocytopenia. Results over the next several quarters will determine whether its FcRn strategy can continue expanding beyond myasthenia gravis and will also test whether empasiprubart can become a second independent product pillar.