Efficacy and Safety Study of GB-0998 for Treatment of Generalized Myasthenia Gravis

Inclusion Criteria: * Patients diagnosed as generalized myasthenia gravis * Patients who are not controlled by current therapy and need plasmapheresis therapy * Patients who have the high-dose steroid therapy for over a month in past years, and also who take steroid or immunosuppressant on the day of consent * Patients who had not any dose increase or new dosing of steroid or immunosuppressant within 4 weeks prior to enrollment Exclusion Criteria: * Patients who received steroid pulse therapy, globulin therapy or plasmapheresis therapy within 12 weeks prior to enrollment * Patients who had undergone thymectomy within 24 weeks prior to enrollment * Patients with 3 points item in bulbar symptom of MG-ADL scale * Patients with severe hepatic disorder, severe renal disorder or severe heat disorder * Patients who have received treatment of malignant tumors * Patients who have the anamnesis of shock or hypersensitivity to this drug * Patients who have been diagnosed as hereditary fructose intolerance * Patients who have the anamnesis of cerebral infarction or symptom of these diseases * Patients who have been diagnosed as IgA deficiency in their past history * Pregnant, lactating, and probably pregnant patients, and patients who want to become pregnant * Patients who were administered other investigational drug within 12 weeks before consent