Objective. To evaluate the efficacy and safety of rituximab in a randomized, double-blind, placebocontrolled phase III trial in patients with lupus nephritis treated concomitantly with mycophenolate mofetil (MMF) and corticosteroids.Methods. Patients (n ‫؍‬ 144) with class III or class IV lupus nephritis were randomized 1:1 to receive rituximab (1,000 mg) or placebo on days 1, 15, 168, and 182. The primary end point was renal response status at week 52.Results. Rituximab depleted peripheral CD19؉ B cells in 71 of 72 patients. The overall (complete and partial) renal response rates were 45.8% among the 72 patients receiving placebo and 56.9% among the 72 patients receiving rituximab (P ‫؍‬ 0.18); partial responses accounted for most of the difference. The primary end point (superior response rate with rituximab) was not achieved. Eight placebo-treated patients and no rituximab-treated patients required cyclophosphamide rescue therapy through week 52. Statistically significant improvements in serum complement C3, C4, and antidouble-stranded DNA (anti-dsDNA) levels were observed among patients treated with rituximab. In both treatment groups, a reduction in anti-dsDNA levels greater than the median reduction was associated with reduced proteinuria. The rates of serious adverse events, including infections, were similar in both groups. Neutropenia, leukopenia, and hypotension occurred more frequently in the rituximab group.Conclusion. Although rituximab therapy led to more responders and greater reductions in anti-dsDNA and C3/C4 levels, it did not improve clinical outcomes after 1 year of treatment. The combination of rituximab with MMF and corticosteroids did not result in any new or unexpected safety signals.Lupus nephritis (LN) may be observed in up to 50% of patients with systemic lupus erythematosus (SLE) and is associated with a poor prognosis (1). Although renal response rates among patients receiving standard treatment of proliferative LN may approach ClinicalTrials.gov identifier: NCT00282347.

Objective B cells are likely to contribute to the pathogenesis of systemic lupus erythematosus (SLE), and rituximab induces depletion of B cells. The Exploratory Phase II/III SLE Evaluation of Rituximab (EXPLORER) trial tested the efficacy and safety of rituximab versus placebo in patients with moderately-to-severely active extrarenal SLE. Methods Patients entered with ≥1 British Isles Lupus Assessment Group (BILAG) A score or ≥2 BILAG B scores despite background immunosuppressant therapy, which was continued during the trial. Prednisone was added and subsequently tapered. Patients were randomized at a ratio of 2:1 to receive rituximab (1,000 mg) or placebo on days 1, 15, 168, and 182. Results In the intent-to-treat analysis of 257 patients, background treatment was evenly distributed among azathioprine, mycophenolate mofetil, and methotrexate. Fifty-three percent of the patients had ≥1 BILAG A score at entry, and 57% of the patients were categorized as being steroid dependent. No differences were observed between placebo and rituximab in the primary and secondary efficacy end points, including the BILAG-defined response, in terms of both area under the curve and landmark analyses. A beneficial effect of rituximab on the primary end point was observed in the African American and Hispanic subgroups. Safety and tolerability were similar in patients receiving placebo and those receiving rituximab. Conclusion The EXPLORER trial enrolled patients with moderately-to-severely active SLE and used aggressive background treatment and sensitive cutoffs for nonresponse. No differences were noted between placebo and rituximab in the primary and secondary end points. Further evaluation of patient subsets, biomarkers, and exploratory outcome models may improve the design of future SLE clinical trials.

Objective To assess the effects of the B-lymphocyte stimulator (BLyS)-specific inhibitor belimumab on immunologic biomarkers, including B- and T-cell populations, and maintenance of antibody titers to prior vaccines in autoantibody-positive systemic lupus erythematosus (SLE) patients. Methods Pooled data from two phase 3 trials—BLISS-52 and -76—comparing belimumab 1 or 10 mg/kg vs placebo (each plus standard SLE therapy) were analyzed for changes in autoantibodies, immunoglobulin (Ig), and complement (C); BLISS-76 patients were analyzed for changes in B- and T-cell populations, and effects on prior vaccine-induced antibody levels. Results Belimumab-treated patients experienced significant sustained reductions in IgG and autoantibodies, and improvement in C3/C4, resulting in greater positive-to-negative conversion rates for IgG anti–double-stranded DNA (anti-dsDNA), anti-Smith, anticardiolipin, and antiribosomal P autoantibodies, and normalization of hypergammaglobulinemia and low C3/C4. Belimumab-treated patients experienced significant decreases in naïve and activated B cells, as well as plasma cells, whereas memory B cells and T-cell populations did not decrease. Belimumab did not substantially affect pre-existing antipneumococcal or antitetanus antibody levels. Post-hoc analysis showed greater reductions in SLE disease activity and the risk of severe flares in patients treated with belimumab 10 mg/kg (P ≤ 0.01) who were anti-dsDNA positive with low C3/C4 at baseline. Normalization of C3 or anti-dsDNA by 8 weeks, irrespective of therapy, was predictive of a reduced risk of severe flare over 52 weeks. Conclusion Belimumab appears to promote normalization of serologic activity and reduce BLyS-dependent B-cell subsets in serologically and clinically active SLE. Greater serologic activity may predict a better treatment response to belimumab.