The purpose of this 2-year extension study is the evaluation of the efficacy and safety 1. after study treatment withdrawal in patients with lupus nephritis (LN) who achieved response (complete renal response \[CRR\] or partial renal response \[PRR\]) on double-blind treatment at the end of the SIRIUS-LN core study, and 2. of open-label ianalumab 300 mg treatment in patients who, at the end of the SIRIUS-LN core study, were either already receiving ianalumab open-label treatment or did not meet CRR/PRR criteria on double-blind treatment at the end of the SIRIUS-LN core study.