Efficacy and Safety of Obinutuzumab in Active Systemic Lupus Erythematosus

Clinical Snapshot

Key Findings

• P Value: P<0.001 for primary endpoint

• Effect Size: Adjusted absolute risk difference: +23.1 percentage points in favour of obinutuzumab; NNT ≈ 4.3

• Primary Outcome: SRI-4 response at Week 52: 76.7% obinutuzumab vs 53.5% placebo (adjusted difference 23.1 percentage points)

• Nnt Or Sensitivity: NNT ≈ 4.3 (primary SRI-4 response); Sensitivity analysis (excluding nonfatal intercurrent events from response definition): 85.4% vs 68.5%, adjusted difference 16.8 percentage points (95% CI 7.1 to 26.4); NNH for serious adverse events ≈ 25 (15.9% vs 11.9%)

• Confidence Interval: 95% CI for primary endpoint: 12.5 to 33.6 percentage points

Clinical Application

Obinutuzumab requires intravenous infusion with pre-medication and monitoring for infusion-related reactions, necessitating infusion centre infrastructure. The dosing schedule (Day 1, Week 2, Week 24, Week 26) requires four infusions per treatment cycle, which is manageable in rheumatology day infusion settings. B-cell monitoring and immunoglobulin surveillance are required. Hypogammaglobulinaemia and infection risk with repeated cycles require ongoing vigilance. The drug is already used in clinical practice for lupus nephritis and haematological malignancies, so familiarity with its safety profile exists among specialist teams. Obinutuzumab (Gazyva/Gazyvaro, Roche) is TGA-approved in Australia for chronic lymphocytic leukaemia and follicular lymphoma, and has received TGA approval for active lupus nephritis (based on the REGENCY trial data). As of the knowledge cutoff, PBS listing for SLE without nephritis does not exist, meaning access would require private funding, compassionate access, or hospital formulary approval. RACGP and Australian Rheumatology Association (ARA) guidelines for SLE management emphasise a treat-to-target approach with hydroxychloroquine as the cornerstone, with belimumab (PBS-listed for active SLE) and voclosporin/mycophenolate for nephritis as established options. If TGA approval for non-nephritis SLE is pursued and granted following this NEJM publication, PBS listing negotiations would be required before broad access. Clinicians should note that rituximab (another anti-CD20 agent) is used off-label for refractory SLE in Australia but is not PBS-listed for this indication. The ALLEGORY data may strengthen the case for B-cell depletion as a therapeutic strategy in SLE beyond nephritis, potentially influencing future ARA position statements. Adults with active SLE (moderate-to-severe disease activity as implied by trial eligibility) without proliferative or membranous lupus nephritis, who have inadequate response or intolerance to standard therapies including antimalarials, immunosuppressants, and low-to-moderate dose glucocorticoids. The trial population likely represents patients with musculoskeletal, cutaneous, haematological, or serositis manifestations of SLE.

Abstract

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.).