Efficacy and Safety of Obinutuzumab in Active Systemic Lupus Erythematosus

BACKGROUND: Obinutuzumab, a glycoengineered type II anti-CD20 monoclonal antibody, induces potent B-cell depletion and is approved for the treatment of active lupus nephritis. Its efficacy and safety in patients with active systemic lupus erythematosus (SLE) are yet to be determined. METHODS: We conducted a phase 3, multicenter, double-blind, placebo-controlled trial involving adults with active SLE but without proliferative or membranous lupus nephritis who were receiving standard therapy. Patients were randomly assigned in a 1:1 ratio to receive obinutuzumab (1000 mg) or placebo on day 1 and weeks 2, 24, and 26. In the prespecified analysis, the primary end point at week 52 was a response on the SLE Responder Index 4 (SRI-4), defined by a reduction from baseline of at least 4 points in the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score, no worsening of disease as assessed by the British Isles Lupus Assessment Group (BILAG) 2004 index and Physician's Global Assessment, and no intercurrent events (i.e., major concomitant-therapy violation, receipt of rescue medication, or early discontinuation of trial participation due to death, lack of efficacy, or adverse events). RESULTS: Of 303 patients who underwent randomization, 151 were assigned to receive obinutuzumab and 152 to receive placebo. At week 52, an SRI-4 response was observed in 76.7% of the patients in the obinutuzumab group and in 53.5% of those in the placebo group (adjusted difference, 23.1 percentage points; 95% confidence interval [CI], 12.5 to 33.6; P<0.001). In an additional analysis whereby nonfatal intercurrent events did not affect response status, the respective percentages were 85.4% and 68.5% (adjusted difference, 16.8 percentage points; 95% CI, 7.1 to 26.4). Obinutuzumab was superior to placebo with respect to all key secondary end points: BILAG-based Composite Lupus Assessment response, sustained reduction in glucocorticoid dose, sustained SRI-4 response, SRI-6 response, and time to first BILAG-defined flare. Adverse events were reported in 88.7% of the patients in the obinutuzumab group and in 81.5% of those in the placebo group, and serious adverse events in 15.9% and 11.9%, respectively. One patient in the obinutuzumab group and 3 in the placebo group died during the double-blind period. CONCLUSIONS: Among adults with active SLE, treatment with obinutuzumab was superior to placebo with respect to the primary and all key secondary end points. (Funded by F. Hoffmann-La Roche; ALLEGORY ClinicalTrials.gov number, NCT04963296.).