Eculizumab for Treatment of Refractory Thymomatous Acetylcholine Receptor Antibody Positive Generalized Myasthenia Gravis
Divya Menghani1, Lauren Williams2, Nakul Katyal1
1Neurology, University of Kentucky, 2University of Kentucky
Objective:
To describe the role of eculizumab for treatment of refractory thymomatous Acetylcholine receptor antibody positive generalized Myasthenia Gravis (AChR+gMG) with frequent exacerbations.  
Background:
Refractory MG associated with thymoma poses a therapeutic challenge, often requiring aggressive immunosuppression. Eculizumab, a recombinant humanized monoclonal antibody that binds to human C5 complement protein and inhibits terminal complement activation, has shown promise in reducing symptoms in refractory MG. 
Design/Methods:
Case report
Results:

A 33-year-old obese female with congenital aortic stenosis s/p bioprosthetic valve placement and refractory thymomatous AChR+gMG on a regimen of pyridostigmine 90 mg every six hours, extended release pyridostigmine 180 mg at bedtime, prednisone (30 mg daily), mycophenolate (1250 mg twice daily), and efgartigimod required three hospital admissions for exacerbations of myasthenia gravis within four months necessitating intravenous immunoglobulin (IVIG) treatment. Computed tomography (CT) chest imaging showed an increase in size of thymoma to 32 x 28 mm which was previously 29 x 23 mm. She subsequently transitioned from efgartigimod to maintenance intravenous immunoglobulin (IVIG) at a dosage of 2 gm/kg every four weeks. Despite addition of maintenance IVIG, her myasthenia gravis activity of daily living (MG-ADL) score remained elevated at 11. Eculizumab was initiated after appropriate vaccination against Neisseria meningitidis. After starting eculizumab, her MG-ADL score improved to 8 within the first two weeks and to 6 by three months. She was able to reduce her prednisone dose to 15 mg daily. Initially deemed ineligible for thymectomy due to significant surgical risks including MG crisis and cardiac complications, her enhanced clinical stability made thymectomy a feasible option for her.

Conclusions:

This case highlights the potential role of eculizumab in managing complex cases of refractory thymomatous AChR+gMG.

10.1212/WNL.0000000000211221
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