A Study to Evaluate the Long-Term Safety of MEDI-545 in Adult Participants With Systemic Lupus Erythematosus or Myositis

Exclusion Criteria

• •Discontinued investigational product (sifalimumab) for safety reasons from any previous sifalimumab clinical study.
• •For participants with systemic lupus erythematosus (SLE): Active severe or unstable neuropsychiatric SLE, that in the opinion of the investigator, would make the participant unsuitable for the study or unable to fully understand the informed consent, Active severe or unstable renal disease that in the opinion of the investigator would make the participant unsuitable for this study
• •For participants with dermatomyositis (DM) or polymyositis (PM): Inclusion body myositis, cancer-associated myositis, myositis associated with another connective tissue disease, environmentally-associated myositis, or drug-related myopathy, a history of or a family history of non-inflammatory myopathy, scapular winging, atrophy, or hypertrophy of the calf muscles, Active Hepatitis A, confirmed positive tests for hepatitis B surface antigen (HbsAg) and hepatitis B core antibody (HbcAb) or hepatitis C serology. Isolated HbcAb positivity will be explored with additional reflex testing to determine eligibility.
• •Evidence of active tuberculosis (TB), either treated or untreated, or latent TB without completion of an appropriate course of treatment or appropriate ongoing prophylactic treatment, history of severe viral infection, such as disseminated herpes, herpes encephalitis, or ophthalmic herpes.
• •Any of the following medications within 6 months before entry into the study: Leflunomide greater than (\>) 20 milligram/day, Cyclophosphamide (or any other alkylating agent).
• •Any of the following medications within 28 days before entry into the study: Prednisone or equivalent \> 30 mg/day or \> 0.5 mg/kg, whichever is the lesser amount, Cyclosporine at any dose, Thalidomide at any dose, Interferon alpha 2b, Hydroxychloroquine \> 600 mg/day, Mycophenolate mofetil \> 3 gram/day, Methotrexate \> 25 mg/week, Azathioprine \> 3 mg/kilogram (kg)/day, Combination of leflunomide and methotrexate
• •Nonstable doses of one or more of the following medications within 28 days before entry into the study: Hydroxychloroquine, Mycophenolate mofetil, Methotrexate, Azathioprine
• •At Screening blood tests (within 28 days before entry into the study), any of the following: Total bilirubin \> upper limit of normal (ULN), Neutrophil count \< 1,500/microliter (mcl) (or \< 1.5 × 109/L), Platelet count \< 60,000/microliter (mcl) (or \< 60 × 109/L), Hemoglobin (Hgb) \< 7 gram per decilitre (g/dL) (or \< 70 g/L).