The purpose of this extension study is to evaluate long-term safety and tolerability of ianalumab administered s.c. monthly or quarterly, compared to monthly placebo, in adolescent and adult participants with anti-nuclear antibody (ANA)-positive systemic lupus erythematosus of moderate-to-severe disease activity, who have completed either CVAY736F12301 (SIRIUS-SLE 1) or CVAY736F12302 (SIRIUS-SLE 2) core studies.