POS0698 BIIB059 DEMONSTRATED A CONSISTENT THERAPEUTIC EFFECT ON SRI-4 RESPONSE ACROSS SUBGROUPS OF PARTICIPANTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS IN THE LILAC PHASE 2 STUDY

Abstract

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.2Objectives: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.2Conclusion: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.