FDA Approves Inebilizumab-Cdon for Treatment of Generalized Myasthenia Gravis

The FDA approved inebilizumab-cdon (Uplizna; Amgen) for the treatment of generalized myasthenia gravis (gMG) in adults who are anti-acetylcholine receptor (AChR) and anti-muscle specific tyrosine kinase (MuSK) antibody-positive.

This action offers patients with gMG a new targeted treatment option that has the potential for long-term disease control with just 2 doses a year, after 2 initial loading doses.¹

Inebilizumab is a humanized monoclonal antibody that targets and depletes key cells that contribute to the underlying disease process (autoantibody-producing CD19+ B cells, including plasmablasts and some plasma cells). After 2 initial infusions, patients need 1 dose of [inebilizumab] every 6 months, which is significant for patients who may have difficulty adhering to treatment because of confusing schedules or frequent dosing.

In addition to this gMG—a rare, unpredictable, chronic, B-cell-mediated autoimmune disorder that impairs neuromuscular communication and can cause fluctuating muscle weakness, trouble breathing, difficulty swallowing, and impaired speech and vision—inebilizumab is also indicated in adult patients for the treatment of anti-aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder and immunoglobulin G4-related disease.¹

"This approval marks a significant advancement for people living with gMG," Jay Bradner, MD, executive vice president of research and development at Amgen, said in a news release. "By selectively targeting CD19-positive B cells, [inebilizumab] offers a new approach to treatment that addresses a biological root cause of disease. [Inebilizumab] is conveniently dosed twice a year and delivers durable efficacy, helping people manage debilitating symptoms that can compromise daily function—including trouble breathing, speaking, and seeing."¹

The approval was supported by positive findings from MINT (NCT04524273)², a randomized, double-blind, placebo-controlled, parallel-group phase 3 trial assessing the efficacy and safety of inebilizumab in adult patients with gMG. A total of 238 patients, including 190 patients who were AChR-positive and 48 patients who were MuSK-positive, were enrolled and randomly assigned to receive either intravenous inebilizumab (300 mg administered on days 1 and 15 for all, and additionally on day 183 for those who were AChR-positive) or a matching placebo for 52 weeks (in participants who were AChR-positive) or 26 weeks (in those who were MuSK-positive).^1,2

The trial’s primary end point was the change from baseline in the score on the Myasthenia Gravis Activities of Daily Living scale (MG-ADL; scores range from 0–24, with higher scores indicating greater disease activity) at week 26 in the combined AChR-positive and MuSK-positive trial populations. Key secondary end point was the change from baseline in the score on the Quantitative Myasthenia Gravis scale (QMG; scores range from 0–39, with higher scores indicating greater disease activity) at week 26 in the combined population. Safety was also assessed.² Clinical findings from MINT were published in The New England Journal of Medicine in June 2025.³

The data demonstrated that patients who received inebilizumab had a greater reduction in MG-ADL score than those who received placebo (least-squares mean change: –4.2 vs –2.2; adjusted difference: –1.9 [95% CI, –2.9 to –1.0; P < .001) at week 26. Additionally, those treated with inebilizumab had a greater reduction in the QMG score than those who received placebo (least-squares mean change: –4.8 vs. –2.3; adjusted difference: –2.5 [95% CI –3.8 to –1.2]; P < .001).³

"[Inebilizumab] showed strong efficacy at 26 weeks in both AChR-positive and MuSK+ patients, with AChR+ patients continuing to improve through 52 weeks in MINT," Richard J. Nowak, MD, MS, global principal investigator and director of the Myasthenia Gravis Clinic at Yale University, said in the news release. "MINT also uniquely required steroid tapering, recognizing that long-term steroid use adds to the overall burden of disease. This approval brings a new first-in-class approach to gMG, expanding treatment options for clinicians and patients."¹

The most common adverse events (AEs) with inebilizumab were headache, cough, nasopharyngitis, infusion-related reactions, and urinary tract infections. Notably, treatment was not associated with a higher incidence of serious AEs.³ The manufacturers caution that patients may experience infections and there may be fetal risks.¹

"Managing a rare and chronic illness can mean facing unpredictable relapsing symptoms and demanding treatment schedules," Samantha Masterson, president and CEO of the Myasthenia Gravis Foundation of America, said in the news release. "This approval marks an important milestone, offering durable efficacy and a dosing schedule that provides people living with gMG 6 months of treatment-free time between maintenance doses."¹

REFERENCES

1. PR Newswire. Fda approves uplizna® for adults with generalized myasthenia gravis. News release. December 11, 2025. Accessed December 12, 2025. https://www.prnewswire.com/news-releases/fda-approves-uplizna-for-adults-with-generalized-myasthenia-gravis-302639699.html

2. Myasthenia Gravis Inebilizumab Trial (MINT). ClincialTrials.gov identifier: NCT04524273. Updated February 20, 2025. Accessed December 12, 2025. https://clinicaltrials.gov/study/NCT04524273

3. Nowak RJ, Benatar M, Ciafaloni E, et al. A Phase 3 Trial of Inebilizumab in Generalized Myasthenia Gravis. N Engl J Med. 2025;392(23):2309-2320. doi:10.1056/NEJMoa2501561