Beyond the LUNAR trial. Efficacy of rituximab in refractory lupus nephritis

Background. The treatment of lupus nephritis (LN) remains problematic because the current treatment regimen based on unspecific immunosuppressants such as steroids, cyclophosphamide and mycophenolate has significant side effects and is often inefficient. B-cell ablation with the chimeric anti-CD20 antibody rituximab (RTX) has been considered as an alternative treatment option but the randomized controlled LUNAR trial failed to show any additive effect of RTX beyond a steroid mycophenolate mofetil (MMF) combination for LN type III/IV/V in incident patients. At present, no such trial is available for the use of RTX in refractory LN. Methods. We analysed existing evidence on this topic by performing a systematic analysis of reports that document outcomes of RTX treatment for refractory LN. Results. Out of 233 reports, we selected 26 for analysis, which described 300 patients with a mean follow-up of 60 weeks. The complete or partial response criteria were met by 87% of patients with LN class III, 76% with class IV and 67% with class V, respectively. Mixed classes responded in 76% of patients. RTX induced complete responses in 60% (type III), 45% (type IV), 40% (type V) and 24% (mixed types), respectively. Conclusions. Our systematic review of existing evidence suggests that RTX effectively induces remission of LN in patients who have not achieved remission with standard therapies. Another randomized controlled trial should be conducted to test the efficacy of RTX in refractory LN.