Efficacy and Safety of Obinutuzumab in Active Lupus Nephritis

Background Obinutuzumab, a humanized type II anti-CD20 monoclonal antibody, provided significantly better renal responses than placebo in a phase 2 trial involving patients with lupus nephritis receiving standard therapy. Methods In a phase 3, randomized, controlled trial, we assigned adults with biopsy-proven active lupus nephritis in a 1:1 ratio to receive obinutuzumab in one of two dose schedules (1000 mg on day 1 and at weeks 2, 24, 26, and 52, with or without a dose at week 50) or placebo. All patients received standard therapy with mycophenolate mofetil, along with oral prednisone at a target dose of 7.5 mg per day by week 12 and 5 mg per day by week 24. The primary end point was a complete renal response at week 76, defined by a urinary protein-to-creatinine ratio of less than 0.5 (with protein and creatinine both measured in milligrams), an estimated glomerular filtration rate of at least 85% of the baseline value, and no intercurrent event (i.e., rescue therapy, treatment failure, death, or early trial withdrawal). Key secondary end points at week 76 included a complete renal response with a prednisone dose of 7.5 mg per day or lower between weeks 64 and 76 and a urinary protein-to-creatinine ratio lower than 0.8 without an intercurrent event. Results A total of 271 patients underwent randomization; 135 were assigned to the obinutuzumab group (combined dose schedules) and 136 to the placebo group. A complete renal response at week 76 was observed in 46.4% of the patients in the obinutuzumab group and 33.1% of those in the placebo group (adjusted difference, 13.4 percentage points; 95% confidence interval [CI], 2.0 to 24.8; P=0.02). A complete renal response at week 76 with a prednisone dose of 7.5 mg per day or lower between weeks 64 and 76 was observed in more patients in the obinutuzumab group than in the placebo group (42.7% vs. 30.9%; adjusted difference, 11.9 percentage points; 95% CI, 0.6 to 23.2; P=0.04), and a urinary protein-to-creatinine ratio lower than 0.8 without an intercurrent event was more common with obinutuzumab than with placebo (55.5% vs. 41.9%; adjusted difference, 13.7 percentage points; 95% CI, 2.0 to 25.4; P=0.02). No unexpected safety signals were identified. More serious adverse events, mainly infections and events related to coronavirus disease 2019, occurred with obinutuzumab than with placebo. Conclusions Among adults with active lupus nephritis, obinutuzumab plus standard therapy was more efficacious than standard therapy alone in providing a complete renal response.