Terminated due to strategic business decision.

Primary objective of the study is to evaluate the effect of abiprubart on an established systemic disease activity measure for Sjögren's Disease.

This is a 56-week (24-week randomized double-blind period, 24-week active treatment period, and 8-week safety follow-up period) multicenter, randomized, double-blind, placebo-controlled, dose-ranging study to evaluate the efficacy and safety of abiprubart in participants with Sjögren's Disease with moderate or high systemic disease activity according to the European League Against Rheumatism (EULAR) Sjögren's Syndrome Disease Activity Index (ESSDAI). The objectives of the study are to evaluate efficacy, safety, pharmacokinetics (PK), and pharmacodynamics (PD) of abiprubart compared with placebo across the estimated therapeutic range using different dosing regimens of abiprubart.

Inclusion Criteria:

• Has a diagnosis of Sjögren's Disease according to 2016 American College or Rheumatology (ACR)-EULAR Classification Criteria.
• Has ESSDAI value ≥ 5, counting only the biological, hematological, articular, cutaneous, glandular, lymphadenopathy, and constitutional organ domains at Screening.
• Is seropositive at Screening for anti-Sjögren's-syndrome-related antigen A autoantibodies (SSA) antibodies tested at a central laboratory.
• Has stimulated whole salivary flow rate at Screening of ≥ 0.05 mL/min
• Weighs at least 40 kg and no more than 150 kg and has a body mass index (BMI) within the range of 18-40 kg/m2.

Exclusion Criteria:

• Prior exposure to any other anti-CD40/CD154 agent.
• Diagnosis of Sjögren's Disease overlap syndromes where another autoimmune rheumatic disease constitutes the principal illness, including fibromyalgia with currently active, inadequately controlled symptoms.
• Has received cataract surgery, Lasik, or other ophthalmologic surgery procedure (e.g., lachrymal plug) in the 6 months prior to Screening.
• Injectable corticosteroids (including intra-articular) within 8 weeks prior to randomization.
• Has started, stopped or adjusted dose/regimen of medications for treatment of, or known to cause dry mouth/eyes within the 30 days prior to screening or is anticipating change to these treatment regimens during the study.
• Has history of immunodeficiency (e.g., immune disorders or disorders that result in decreased immunity), including human immunodeficiency virus (HIV).
• History of thromboembolic event or a significant risk of future thromboembolic events.
• Has a known high risk of infection; Has a history of chronic or recurrent infectious disease; Has any known or suspected active infection, or has had a serious infection requiring hospitalization, or has been treated with IV/IM antibiotics for an infection within 8 weeks prior to first dose of study drug or treatment with oral antibiotics for an infection within 2 weeks prior to first dose of study drug.