Inebilizumab Improves Generalized Myasthenia Gravis Symptoms in Phase 3 Trial

Inebilizumab, a monoclonal antibody targeting CD19+ B-cells, has demonstrated significant efficacy in improving symptoms of generalized myasthenia gravis (gMG), according to study results presented at the 2025 American Academy of Neurology (AAN) annual meeting, held from April 5 to 9, 2025, in San Diego, California.

The Myasthenia Gravis Inebilizumab Trial (MINT; ClinicalTrials.gov Identifier: NCT04524273) was designed to assess the efficacy and safety of inebilizumab in adult patients with gMG who tested positive for either acetylcholine receptor (AChR+) or muscle-specific kinase (MuSK+) antibodies. The study included a protocol-mandated steroid taper to evaluate the drug’s ability to reduce disease severity while minimizing reliance on corticosteroids.

Researchers randomly assigned 238 patients in a 1:1 ratio to receive either inebilizumab (300 mg intravenously on Days 1 and 15, with an additional dose at Week 26 for AChR+ patients) or placebo. The trial included a 52-week randomized controlled period (RCP) for AChR+ participants and a 26-week RCP for MuSK+ participants.

The primary efficacy endpoint was the change from baseline in the Myasthenia Gravis Activities of Daily Living (MG-ADL) score at Week 26 in the combined population. Secondary endpoints included changes in the Quantitative Myasthenia Gravis (QMG) score and separate efficacy analyses in AChR+ and MuSK+ subgroups.

At Week 26, the inebilizumab group vs the placebo group demonstrated a significantly greater improvement in MG-ADL scores (-4.2 vs -2.2, respectively), with a mean difference of -1.9 points (95% CI, -2.9, -1.0; P <.001). Similarly, patients who were treated with inebilizumab showed a greater reduction in QMG scores (-4.8 vs -2.3 in placebo), with a mean difference of -2.5 points (95% CI, -3.8, -1.2; P<.001).

Adverse events (AEs) were observed in 80.7% of patients treated with inebilizumab and 73.1% of those who received a placebo. Serious AEs were reported in 8.4% of the inebilizumab group vs 13.4% in the placebo group.

These findings suggest that inebilizumab provides a clinically meaningful benefit in reducing disease burden for patients with AChR+ or MuSK+ gMG while maintaining an acceptable safety profile.

“Targeting an upstream immunopathogenic mechanism may be an effective tool in reducing disease severity and steroid burden,” the researchers concluded.

Multiple study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.