UCB Proof of Concept Study in Patients With Primary Sjögren's Syndrome

Inclusion Criteria: * Subject must be between 18 years and 75 years of age * Women of childbearing potential must agree to use a highly effective method of birth control during the study and for a period of 3 months after their final dose of study drug. Women not agreeing to use birth control must be of non-childbearing potential defined as; permanently sterile, congenitally sterile or postmenopausal for at least 2 years prior to Screening (Visit 1). Women of childbearing potential are required to have a serum pregnancy test taken at Screening (Visit 1), which is confirmed to be negative by urine testing prior to the first dose of study drug at Week 1 (Visit 2) Male subjects with a partner of childbearing potential must be willing to use a condom when sexually active during the study and for 3 months after the last dose of study drug In addition female partner of childbearing potential of male subject must be willing to use a highly effective method of contraception for duration of study and for 3 months after last dose of study drug * Subject must meet the 2002 AECG (American-European Consensus Group) criteria for Primary Sjӧgren's Syndrome * Subject must have a serum test positive for anti-SSA/Ro (Ro-52 or Ro-60) and/or anti SSB/La autoantibodies Exclusion Criteria: * Subject has a diagnosis of any other autoimmune disease, ie, secondary Sjögren's syndrome (eg, rheumatoid arthritis, systemic lupus erythematosus * Subject has a diagnosis of any other sicca syndrome (eg, history of head and neck radiation treatment, sarcoidosis chronic graft-versus-host disease) * Subject has significant fibromyalgia syndrome as defined by the American College of Rheumatology 2010 classification criteria * Subject has significant depression as defined by the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders * Subject has oral candidiasis * Subject is female and is breast-feeding, pregnant, or plans to become pregnant or to start breastfeeding during the study or within 3 months after the final dose of the investigational medicinal product (IMP) * Subject has evidence of an immunosuppressive state, including human immunodeficiency virus (HIV) infection, hypogammaglobulinemias, T-cell deficiencies, or human T-cell leukemia virus type 1 (HTLV-1) o Positive testing for HIV-1/2 at Screening (Visit 1) * Subject has a history of chronic infections, including but not limited to concurrent acute or chronic viral hepatitis B (HBV) or hepatitis C (HCV) * Positive testing for HBV at Screening (Visit 1) * Positive testing for HCV at Screening (Visit 1) * A subject with a history of a recent serious or life-threatening infection or any current signs or symptoms that may indicate a significant infection at Screening (Visit 1) to randomization, as per the Investigator's clinical judgment is also excluded Subject must have completed any prior anti-infective therapy prior to the first dose of study drug with the exception of anti-infectives taken specifically for the treatment of acne, rosacea, onychomycosis, or vaginal yeast infections; for the prophylaxis of urinary tract infections; or prophylaxis for pre-surgical or pre-procedural reasons (including dental procedures). Note: minocycline may not be used for these purposes * Subject is at a particularly high risk of significant infection due to their lifestyle and/or occupation * Subject has received intranasal influenza vaccine within the 8 weeks prior to Screening (Visit 1) * Subject has significant hematologic abnormalities of hemoglobin \<10.0 g/dL, or white blood cell (WBC) \<2000 /mm\^3, or absolute neutrophil count \<1000 /mm\^3, or platelets \<100,000 /mm\^3 at Screening (Visit 1) * Subject has a history of cancer