Inebilizumab Maintains Therapeutic Efficacy in AChR+ Generalized Myasthenia Gravis

New 52-week data from the phase 3 MINT trial demonstrate sustained improvements in disease burden among patients with acetylcholine receptor antibody–positive generalized myasthenia gravis (AChR+ gMG) treated with inebilizumab (Uplinza; Amgen), reinforcing the durability of response previously observed at earlier time points.¹

Presented at the 2026 American Academy of Neurology (AAN) Annual Meeting by Richard J Nowak, MD, MS, and colleagues, the updated analysis focused on the AChR+ subgroup within the randomized, placebo-controlled MINT trial (NCT04524273). The study evaluated efficacy, pharmacodynamics, and immunogenicity of inebilizumab, a CD19-targeting monoclonal antibody designed to deplete a broad range of B cells implicated in autoantibody production.²

At week 52, treatment with inebilizumab was associated with a statistically significant improvement in Myasthenia Gravis Activities of Daily Living (MG-ADL) scores compared with placebo (adjusted difference, –2.8; 95% CI, –3.9 to –1.7; nominal P <.001).¹ Similarly, patients receiving inebilizumab demonstrated greater reductions in Quantitative Myasthenia Gravis (QMG) scores (adjusted difference, –4.3; 95% CI, –5.9 to –2.8; nominal P <.001), suggesting consistent benefit across functional and clinician-assessed outcomes.¹

These findings build on previously reported results from the same phase 3 trial, which showed significant improvements in MG-ADL at week 26 (–4.2 with inebilizumab vs –1.9 with placebo; P <.0001), supporting the therapy’s initial efficacy signal. In that earlier analysis, improvements in QMG scores were also observed, with reductions of –4.8 in the treatment group compared with –2.5 in the placebo arm (P = .0002).

Pharmacodynamic data from the updated analysis demonstrated rapid and sustained depletion of CD20+ B cells, with levels reduced by 93.3% from baseline within 2 weeks of treatment initiation and remaining suppressed throughout the study period. Immunogenicity rates were low, with anti-drug antibodies observed in 4.2% of inebilizumab-treated patients compared with 2.1% in the placebo group.¹

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The MINT trial enrolled 238 patients with gMG, of whom 190 were AChR+, randomized 1:1 to receive intravenous inebilizumab 300 mg or placebo on days 1, 15, and 183, with a total follow-up of 52 weeks.¹ Participants entered the study with clinically meaningful disease burden, including MG-ADL scores of at least 6 and QMG scores of at least 11.

Inebilizumab, marketed as Uplizna, is a humanized monoclonal antibody that targets CD19-positive B cells, including plasmablasts and some plasma cells, offering a broader depletion profile compared with CD20-directed therapies. This mechanism is thought to more directly impact autoantibody production, a central driver of gMG pathophysiology.²

The therapy received FDA approval in 2025 for adults with AChR- and MuSK-positive gMG, based on the MINT trial data demonstrating clinically meaningful and statistically significant improvements in MG-ADL and QMG scores. The approval positioned inebilizumab as the first CD19-targeted therapy for gMG, with a dosing schedule that includes 2 initial infusions followed by maintenance dosing every 6 months.

Taken together, the 52-week findings further contextualize the durability of inebilizumab’s effect, suggesting that sustained B-cell depletion may translate into continued clinical benefit over time. While longer-term and real-world data remain important for defining its place in therapy, these results add to the growing body of evidence supporting targeted B-cell approaches in gMG management.¹

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REFERENCES
1. Clarkson K, Utsugisawa K, Benatar M, et al. Myasthenia gravis inebilizumab trial (MINT): efficacy, pharmacodynamics, and immunogenicity in AChR+ cohort (Week 52). Presented at: 2026 American Academy of Neurology Annual Meeting; April 18–22, 2026; Chicago, IL.
2. FDA Approves UPLIZNA® For Adults With Generalized Myasthenia Gravis. News release. Amgen. December 11, 2025. Accessed April 19, 2026. https://investors.amgen.com/news-releases/news-release-details/fda-approves-upliznar-adults-generalized-myasthenia-gravis
3. Amgen Conference Call to Discuss New Topline Data in Inflammation and Rare Disease. News release. Amgen. September 24, 2024. Accessed April 19, 2026. https://amgen2.rev.vbrick.com/#/videos/750c4b9d-5c91-4634-8906-a16b53f346bf.