Amgen wins European approval to challenge argenx and UCB for autoimmune market

Belgian-Dutch biotech Argenx won European approval for its FcRn blocker Vyvgart in gMG in 2022 and secured authorization for a subcutaneous formulation of the therapy in 2023. The Commission approved UCB’s Rystiggo and J&J’s Imaavy in gMG in 2024 and 2025, respectively. Like Vyvgart, Rystiggo and Imaavy work by blocking FcRn to cut levels of the immunoglobulin G autoantibodies that drive gMG, a rare autoimmune disease that causes muscle weakness.

Amgen’s Uplizna uses a different mechanism to disrupt autoantibody production. By targeting and depleting CD19-positive B cells, Amgen’s monoclonal antibody is designed to lower levels of the immune cells that make autoantibodies and otherwise contribute to gMG. Amgen previously won approvals for Uplizna in the U.S. and European Union in neuromyelitis optica spectrum disorders and immunoglobulin G4-related disease, rare autoimmune conditions that respectively affect the eyes and multiple organs.

Differentiating Uplizna

Amgen won approval based on a Phase III trial that linked Uplizna to a 2.8-point reduction on a disease severity scale compared to placebo after 52 weeks. The company reported a 4.3-point improvement on a clinician-reported gMG tool. TD Cowen analysts said in a note to investors that the result was better than C5 inhibitors such as AstraZeneca’s Ultomiris and competitive versus Vyvgart.

Patients receive Uplizna intravenously, beginning with two starting doses two weeks apart before moving to maintenance dosing every six months. The dosing regimen sets Uplizna apart from the FcRn blockers. J&J’s Imaavy is given intravenously every two weeks. Patients take multi-week cycles of Vyvgart and Rystiggo, both of which are available subcutaneously, broken up by multi-week treatment breaks.  

At the J.P. Morgan Healthcare Conference in January, Amgen CEO Robert Bradway named Uplizna’s “very convenient dosing regimen” as a potential advantage over other therapies. Amgen will seek to leverage its potential advantage to capture a share of the European market, both by persuading people to switch to Uplizna and by targeting treatment-naive patients. 

“This is an area … where we expect both to benefit from the churn that occurs in this community clinically, but also expect to be prescribed for a number of patients who are encountering therapy for the first time,” Bradway said.

BMO Capital Markets analysts shared similar views, writing in a note to investors that they see “favorable positioning of Uplizna with its bi-yearly dosing regimen and unique [mechanism of action] of targeting CD19+ B cells, which may provide more durable treatment effect.” The analysts said gMG is a key growth opportunity for the product, sales of which grew 131% in the fourth quarter.

Argenx executives are confident they can retain market share amid growing competition. Asked about Uplizna on an earnings call in July, argenx Chief Operating Officer Karen Massey said, “competition is certainly heating up” but argued the company is “very well positioned to continue to lead and to continue to be the fastest-growing biologic within that expanding biologic market in MG.”

European approvals lag behind

Amgen won approval for Uplizna in gMG in the U.S. in December. The timing follows the typical schedule of Europeans gaining access to medicines later than people in the U.S., even when the products are developed by European companies. The U.S. Food and Drug Administration (FDA) authorized Vyvgart in gMG almost eight months before the Commission approved the drug for use in the European Union.

Similarly, Brussels-based UCB won FDA approval for Rystiggo six months before securing authorization to sell the drug in its home market. J&J, a U.S.-based drugmaker, landed FDA approval for Imaavy months before getting the green light to market the product in the EU. Taken together, the approvals illustrate a consistent pattern of earlier market access in the U.S. compared with the EU.