FDA Approves Inebilizumab for Generalized Myasthenia Gravis

Inebilizumab-cdon (Uplizna; Amgen) is now approved to treat adults with anti-acetylcholine receptor (AChR) and anti-muscle specific tyrosine kinase (MuSK) antibody–positive generalized myasthenia gravis (gMG), based on MINT trial results (NCT04524273).¹ Among the more notable findings, MINT is the first trial to incorporate a steroid taper into its protocol; by week 26, 87.4% of the enrolled patients who were receiving inebilizumab were able to reduce their daily steroid dose to 5 mg or less.

MINT topline data made a splash earlier this year with research presented at the American Academy of Neurology annual meeting. In those results, the CD19-directed B-cell–depleting therapy had met its primary end point by 26 weeks following treatment initiation, sustained benefit was seen at 52 weeks in those who were AChR positive, and there were statistically significant improvements in muscle strength and fatigability.²

The intravenous treatment is administered via 2 initial loading doses of 300 mg, given 2 weeks apart, and then 2 more 300-mg doses over the next year, 6 months apart.³

In the randomized, double-blind, placebo-controlled, parallel-group MINT trial, patients were AChR-positive (n = 190) or MuSK-positive (n = 48).¹ To be enrolled, all had to have class II through IV disease per Myasthenia Gravis Foundation of America (MGFA) criteria; a Myasthenia Gravis Activities of Daily Living (MG-ADL) score between 6 and 10, of which more than 50% was due to nonocular causes, or an MG-ADL score of at least 11; a Quantitative Myasthenia Gravis (QMG) score of at least 11; and be on a stable dose of steroids, an immunosuppressant, or both at randomization. The primary end point was MG-ADL score change from baseline at week 26 in the total study population, and key secondary end points were MG-ADL score change from baseline at week 26 for each study arm, and QMG score change from baseline at week 26 for each study arm

Drilling down to the noteworthy results, there was an approximate 1.9-point difference in MG-ADL score for the treated patients compared with those who received placebo, at –4.2 vs –2.2 (P < .0001), and through week 52, this gap only widened to 2.8 points, for a 4.7-point decrease among the patients who received inebilizumab and a 1.9-point decrease for the placebo cohort.

The following principal results also were seen at week 26, all for patients who received inebilizumab vs placebo:

• QMG score difference of 2.5 points overall: –4.8 vs – 2.3 (P = .0002)
• MG-ADL score difference of 1.8 points for AChR+ patients: –4.2 vs –2.4 (P = .0015)
• QMG score difference of 2.5 points for AChR+ patients: –4.4 vs –2.0 (P = .0011)
• MG-ADL score difference of 2.2 points for MuSK+ patients: –3.9 vs –1.7 (P = .0297)
• QMG score difference of 2.3 points for MuSK+ patients: –5.2 vs –3.0 (P = .1326)

There also was an exploratory analysis conducted just among AChR+ patients through week 52. In addition to the 2.8-point difference in MG-ADL score and steroid taper results previously mentioned, QMG score dropped by 5.8 points for the inebilizumab cohort vs 1.4 for the placebo cohort (95% CI, –5.9 to –2.8).

With gMG on the rise globally, this third indication for inebilizumab adds to the treatment armamentarium for patients living with gMG. The monoclonal antibody also is approved to treat adults patients who have anti-aquaporin-4 antibody–positive neuromyelitis optica spectrum disorder and immunoglobulin G4-related disease.⁴

"Managing a rare and chronic illness can mean facing unpredictable relapsing symptoms and demanding treatment schedules," Samantha Masterson, president and CEO of MGFA, said in a statement.¹ "This approval marks an important milestone, offering durable efficacy and a dosing schedule that provides people living with generalized myasthenia gravis six months of treatment-free time between maintenance doses."

References

1. FDA approves Uplizna for adults with generalized myasthenia gravis. News release. Amgen. December 11, 2025. Accessed December 12, 2025. https://www.amgen.com/newsroom/press-releases/2025/12/fda-approves-uplizna-for-adults-with-generalized-myasthenia-gravis
2. Shaw M, Nowak R. Targeting the root of gMG with inebilizumab: a Q&A with Richard Nowak, MD, MS. AJMC^®. June 24, 2025. Accessed December 12, 2025. https://www.ajmc.com/view/targeting-the-root-of-gmg-with-inebilizumab-a-q-a-with-richard-nowak-md-ms
3. Uplizna. Prescribing information. Amgen; 2024. Accessed December 12, 2025. https://www.upliznahcp.com/nmosd/dosing-and-infusion-information/administration
4. McNulty R. Inebilizumab FDA approved as first treatment for IgG4-RD. AJMC. April 3, 2025. Accessed December 12, 2025. https://www.ajmc.com/view/inebilizumab-fda-approved-as-first-treatment-for-igg4-rd