A Study to Evaluate the Efficacy and Safety of Abiprubart in Participants With Sjögren's Disease

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.