Background: Type I interferons and other inflammatory mediators derived from plasmacytoid dendritic cells (pDCs) are implicated in systemic lupus erythematous (SLE) pathology. BIIB059 is a humanized monoclonal antibody that targets blood dendritic cell antigen 2 (BDCA2), a pDC-specific receptor. The binding of BIIB059 to BDCA2 leads to rapid internalization of BDCA2 from the surface of pDCs and subsequent inhibition of interferon, cytokine, and chemokine production. In Part A of the 2-part, phase 2 LILAC study (NCT02847598), BIIB059 significantly reduced SLE activity, as evidenced by reduced total active joint count (primary endpoint) and higher SLE Responder Index (SRI-4)¹ response (a secondary endpoint) versus placebo.²

Objectives: To evaluate SRI-4 response for BIIB059 versus placebo at Week 24 in SLE participant subgroups.

Methods: Enrollment in LILAC Part A was open to adults fulfilling ≥ 4 of 11 revised 1997 ACR criteria for classification of SLE, with ≥ 4 tender and ≥ 4 swollen joints, active skin disease, and positive lupus antibodies. Participants were randomized to receive either BIIB059 450 mg or placebo subcutaneously every 4 weeks for 20 weeks (with an additional dose at Week 2). SRI-4 response at Week 24 was analyzed in subgroups, though analyses were limited by small sample sizes and were not powered for statistical testing.

Results: In LILAC Part A, 64 and 56 participants were dosed with BIIB059 450 mg and placebo, respectively. At week 24, SRI-4 response rate was observed in favor of BIIB059 regardless of the baseline disease activity, such as SLEDAI-2K <10 versus ≥10, presence of BILAG-2004 grade A or B arthritis, oral corticosteroid usage, positivity for anti-ds DNA autoantibody and/or complement status, with point estimates for least-squares mean differences as well as corresponding 95% CIs consistently favoring BIIB059 (Figure 1). The incidence of adverse events in the overall study population was similar between the placebo and BIIB059 groups.²

Conclusion: BIIB059 treatment was associated with greater SRI-4 response rate, consistent among different subgroups of baseline disease activity as measured by SLEDAI-2K and BILAG-2004, glucocorticoid dosage, and serology. These findings provide additional evidence of the potential benefit of BIIB059 for the treatment of patients with active SLE.

References: [1]Furie RA, et al. Arthritis Rheum. 2009;61(9):1143-1151. 2. Furie RA, et al. Arthritis Rheumatol. 2020;72(suppl 10). Abstract 0935.

Acknowledgements: This study was sponsored by Biogen (Cambridge, MA, USA). Writing and editorial support was provided by Excel Scientific Solutions (Fairfield, CT, USA); funding was provided by Biogen.

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Disclosure of Interests: Ronald van Vollenhoven Consultant of: AbbVie, AstraZeneca, Biotest, Bristol Myers Squibb, Celgene, GlaxoSmithKline, Janssen, Lilly, Medac, Merck, Novartis, Pfizer, Roche, UCB, Grant/research support from: AbbVie, Arthrogen, Bristol Myers Squibb, GlaxoSmithKline, Lilly, Pfizer, UCB, Richard Furie Consultant of: Biogen, Grant/research support from: Biogen, Kenneth Kalunian Consultant of: AbbVie, Amgen, AstraZeneca, Biogen, Bristol Myers Squibb, Eli Lilly, Equillium, Genentech, Gilead, ILTOO, Janssen, Nektar, Roche, Viela, Grant/research support from: Lupus Research Alliance, Pfizer, Sanford Consortium, Sandra Navarra Speakers bureau: Astellas, Johnson & Johnson, Novartis, Pfizer, Consultant of: Biogen, Grant/research support from: Biogen, Juanita Romero-Diaz Consultant of: Biogen, Boehringer Ingelheim, Victoria Werth Consultant of: AbbVie, Amgen, AstraZeneca, Biogen, Bristol Myers Squibb, Eli Lilly, EMD Serono, Gilead, GlaxoSmithKline, Janssen, Kyowa Kirin, Resolve, Viela, Grant/research support from: Biogen, Celgene, Gilead, Janssen, Viela, XIAOBI HUANG Shareholder of: Biogen, Employee of: Biogen, HUA CARROLL Shareholder of: Biogen, Employee of: Biogen, Cristina Musselli Shareholder of: Biogen, Employee of: Biogen, Catherine Barbey Shareholder of: Biogen, Employee of: Biogen, NATHALIE FRANCHIMONT Shareholder of: Biogen, OMass Therapeutics, Employee of: Biogen