Effective efgartigimod treatment for severe thymoma‐associated myasthenia gravis experiencing myasthenic crisis: A case report

We report the long‐term treatment of a 38‐year‐old man with generalized thymoma‐associated myasthenia gravis who was treated with efgartigimod. He received chemotherapy and oral prednisolone before the thymectomy. However, after initial improvement in symptoms, he deteriorated and needed continuous noninvasive positive‐pressure ventilation, with the highest Myasthenia Gravis‐Activities of Daily Living score of 14. Immunosuppressive therapy and plasma exchange showed limited benefit, and the anti‐acetylcholine receptor antibody titer peaked to 130 nmol/L. Seven cycles of efgartigimod treatment were administered, which improved the symptoms, achieving a Myasthenia Gravis‐Actvities of Daily Living score of 0. The anti‐acetylcholine receptor antibody titer fluctuated until the end of the fifth cycle, thereafter, plateauing at 22 nmol/L. These findings allowed the prednisolone dose to be tapered and the interval between the treatment cycles to be increased.