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

The primary objective of this study is to evaluate the long-term safety and tolerability of multiple intravenous (IV) doses of sifalimumab in adult participants with active SLE or DM or PM who were previously treated with investigational product (sifalimumab or placebo) in one of the following sifalimumab clinical studies: MI-CP151, MI-CP152, or MI-CP179.