On Thursday, the U.S. Food and Drug Administration (FDA) approved an expanded use for Amgen’s autoimmune therapy Uplizna. The approval now allows the drug to be used in adults with generalized myasthenia gravis who test positive for autoantibodies against the anti-acetylcholine receptor (AChR) and anti-muscle specific tyrosine kinase (MuSK).
Amgen stated that Uplizna is the first CD19-targeted B cell therapy approved for this indication. The company highlighted that patients can achieve long-term disease control with only two doses per year.
The decision was based on results from the Phase III MINT study. Data released in September 2024 showed significant improvements in daily living activities at 26 weeks, measured by the Myasthenia Gravis Activities of Daily Living (MG-ADL) scale, compared to placebo. These benefits were seen in both AchR-positive and MuSK-positive subgroups.
Further follow-up data published by Amgen in March indicated that Uplizna maintains and deepens its treatment response over one year. The placebo-adjusted improvement in MG-ADL increased to 2.8 points at one year from 1.8 points at 26 weeks. Additionally, scores on the Quantitative Myasthenia Gravis scale improved by 4.3 points at one year, up from a 2.5-point average improvement at 26 weeks.
Analysts at William Blair commented on these findings: “These data solidify a meaningful role for Uplizna in the treatment of myasthenia gravis” and support its “blockbuster potential.” They also noted that the therapy’s “infrequent every-six-month dosing interval” will give it an edge over “weekly, monthly, or every-other-month dosing regimens with other therapies.”
Uplizna is an IgG1 monoclonal antibody designed to target CD19 on immature and mature B cells. While its exact mechanism of action in myasthenia gravis is not fully understood, it may work by depleting B cells involved in driving disease pathology.
Myasthenia gravis causes muscle weakness as well as problems with breathing, swallowing, and speech.
Uplizna was first approved by the FDA in 2020 for neuromyelitis optica spectrum disorder, a rare autoimmune condition affecting the optic nerve, spinal cord, and brain stem. In April this year, it received another label expansion for IgG4-related disease.
