Evaluation of Tabalumab Using Auto-Injector or Prefilled Syringe in Participants With Rheumatoid Arthritis (RA)

Inclusion Criteria:

• Ambulatory males or females ≥18 years of age
• Diagnosis of adult-onset RA
• Active RA (at least 8/68 tender and at least 8/66 swollen joints)
• Screening C-reactive protein >1.2 times the upper limit of normal (ULN) or a screening erythrocyte sedimentation rate (ESR) >28 millimeters per hour (mm/hr)
• Documented history of, or current, positive rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibody (anti-CCP Ab) test
• Regular use of methotrexate (MTX) for at least 12 weeks and stable dose (10 to 25 mg/week) for at least 8 weeks prior to baseline
• American College of Rheumatology (ACR) functional class I, II, or III
• Able and willing to inject tabalumab by themselves (or have an assistant who will inject tabalumab) and able and willing to complete all study procedures
• Able and willing to have blood drawn for pharmacokinetic (PK) sampling

Exclusion Criteria:

• Use of oral corticosteroids at average daily doses of >10 mg/day of prednisone or its equivalent within 6 weeks prior to baseline
• Injection of any parenteral (including intraarticular) corticosteroid within 6 weeks of baseline
• Have previously discontinued treatment with a biologic disease-modifying antirheumatic drug (DMARD) or a novel drug that interrupts cytokine signaling (eg, Janus kinase [JAK] inhibitors) due to insufficient efficacy
• Participants who had discontinued biologic DMARDS for reasons other than efficacy will not be excluded but must have done so prior to baseline
• Participants who discontinued a JAK inhibitor for lack of efficacy
• Participants who discontinued a JAK inhibitor for reasons other than efficacy will not be excluded, but must have done so prior to baseline for 21 days
• Previous severe reaction to any biologic therapy that, in the opinion of the Investigator, would pose an unacceptable risk to the participant if participating in the study
• Have had an inadequate response to treatment with 3 or more of the following DMARDs prescribed alone or in combination at approved doses for a minimum of 90 days: leflunomide, azathioprine, cyclosporine, and/or sulfasalazine
• Use of other DMARDs (eg, gold salts, cyclosporin, azathioprine, or any other immunosuppressives) other than MTX, hydroxychloroquine, chloroquine, or sulfasalazine, or the use of a JAK inhibitor in the 8 weeks prior to baseline