Amgen's Uplizna Shows Promise in Myasthenia Gravis, But Faces Stiff Competition

Amgen's anti-CD19 antibody Uplizna (inebilizumab) has demonstrated durable and deepening treatment effects for patients with generalized myasthenia gravis (gMG), according to new data presented at the 2025 Annual Meeting of the American Academy of Neurology and published in the New England Journal of Medicine. However, analysts note that the drug's slow onset of action may put it at a disadvantage compared to competitors in the gMG market.

Efficacy and Safety Profile

The latest data show that Uplizna maintained improved function and disease activity through one year of follow-up in gMG patients. Significant improvements in activities of daily living were observed compared to placebo at 26 weeks, along with a notable reduction in quantitative disease activity.

Safety data indicated that Uplizna was not associated with more frequent serious toxicities than placebo. Common side effects included headache, cough, urinary tract infections, and infusion-related reactions.

Competitive Landscape

While Uplizna's end response is comparable to other drugs in its class, such as UCB's Rystiggo and argenx's Vyvgart, Leerink analysts point out that its "gradual effectiveness" may be a drawback. Patients on Uplizna only began to show initial separation from placebo in terms of activities of daily living after 8 weeks, reaching statistically significant separation at 26 weeks.

This slower onset of action contrasts unfavorably with Vyvgart, which significantly distinguishes itself from placebo as early as week 1, according to the analysts.

Regulatory Strategy and Expanded Indications

Amgen plans to file for approval of Uplizna in gMG in the first half of 2025. The drug, which targets and binds the CD19 protein found on B cells, was first approved in 2020 for neuromyelitis optica spectrum disorder.

Recently, Uplizna received FDA approval for IgG4-related disease, where it has shown the ability to reduce disease-related flares by 87% versus placebo and eliminate the need for glucocorticoids in nearly 90% of patients, based on results from the Phase III MITIGATE trial.

As Amgen continues to expand Uplizna's indications, the pharmaceutical industry will be watching closely to see how it performs in the competitive gMG market, particularly given its slower onset of action compared to existing treatments.