INCB047986 in Rheumatoid Arthritis

Inclusion Criteria: * Men or women aged 18 to 75 years, inclusive. * Body mass index between 18 and 40 kg/m\^2, inclusive. * Subjects must have a diagnosis of rheumatoid arthritis (RA) of at least 6 months' duration at the time of screening and must satisfy the ACR/European League Against Rheumatism (EULAR) 2010 Classification Criteria (Appendix B). * Subjects must have active moderate to severe RA as determined by the following: * ≥ 6 tender joints (28 joint count), * ≥ 4 swollen joints (28 joint count), and * CRP level ≥ 6 mg/L. * Subjects must have a negative tuberculosis (TB) test (QuantiFERON®-TB Gold test or purified protein derivative (PPD)) at screening. Exclusion Criteria: * Current or recent history of severe and/or progressive uncontrolled renal, hepatic, hematologic, gastrointestinal, pulmonary, cardiac, neurological, or cerebral disease. * Current or recent history (\< 30 days before screening and/or \< 45 days before randomization) of a clinically meaningful bacterial, fungal, parasitic, or mycobacterial infection. * Onset of RA before the age of 16 years. * History of known or currently suspected inflammatory disease other than RA * Current regimen of prednisone or equivalent with an average daily dose of \> 10 mg or having been treated with a stable daily dose ≤ 10 mg for \< 6 weeks. * Previous treatment with at Janus kinase (JAK) inhibitor. * Significant impairment of bone marrow function present at screening * Receipt of any live vaccine within 2 months before screening or anticipated need for a live vaccine within the 2 months after last dose of study drug.