Efficacy and Safety Study of GB-0998 for Treatment of Steroid-resistant Polymyositis and Dermatomyositis (PM/DM)

Inclusion Criteria: Patients who have been defined as "definite" based on the criteria of Bohan and Peter for polymyositis and dermatomyositis. Patients who are defined as steroid-resistant ones based on the changes of scores on manual muscle testing (MMT) and serum levels of creatine kinase (CK) during observation period before administration of drug. Exclusion Criteria: Patients with malignant tumors. Patients with acute interstitial pneumonia, including acute exacerbation of chronic. Patients with severe muscular atrophy for a long period. Patients with severe infectious disease. Patients who have the anamnesis of shock or hypersensitivity to this drug. Patients with severe hepatic disorder or severe renal disorder. Patients who have the anamnesis of cerebral infarction or ischemic heart disease, or who having 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 immunoglobulin dosage within 6 weeks before consent.