We report the case of a 19-year-old woman with progressive proliferative lupus 
nephritis (LN) class III after induction and maintenance therapy with 
mycophenolate mofetil (MMF). Despite a satisfying clinical improvement 
proteinuria progressed under this medication. We treated the patient with 
additional belimumab after discussing other options. Following treatment with 
belimumab, proteinuria rapidly improved to almost normal levels and clinical 
remission lasted. Belimumab might hold promise for this indication.