A Synovial Biopsy Study of JNJ-38518168 in Participants With Active Rheumatoid Arthritis Despite Methotrexate Therapy

Inclusion Criteria: * Have had rheumatoid arthritis (RA) for at least 6 months prior to the date of signing the informed consent at screening * Be positive for either anti-cyclic citrullinated peptide (anti-CCP) antibody or rheumatoid factor (RF) in serum at screening * Have active RA defined for the purpose of this study as persistent disease activity with both of the following criteria: At least 4 swollen and 4 tender joints using a 66/68 joint count. At the time of screening, one of the tender or swollen joints or both must include the non-prosthetic knee to be biopsied; and serum C-reactive protein (CRP\_ ≥ 0.60 mg/dL at screening * Have been treated with and tolerated oral methotrexate (MTX) treatment at doses from 10 mg/week to 25 mg/week inclusive, for a minimum of 3 months prior to the date of signing the informed consent at screening and must have a stable MTX dose for a minimum of 8 weeks prior to the date of signing the informed consent at screening and continue to receive the same MTX dose at Week 0 * If using nonsteroidal anti-inflammatory drugs (NSAIDs) or other analgesics (pain relievers) regularly for RA, the participant must have been on a stable dose for at least 2 weeks prior to the first administration of study agent. If not using NSAIDs or other analgesics for RA at Week 0, the participant must have not received NSAIDs or other analgesics for RA for at least 2 weeks prior to the first administration of study agent Exclusion Criteria: * Has inflammatory diseases other than RA * Has a history of juvenile idiopathic arthritis (JIA) * Has current signs or symptoms of liver or renal insufficiency or cardiac, vascular, pulmonary, gastrointestinal, endocrine, neurologic, hematologic, psychiatric, or metabolic disturbances that are severe, progressive, or uncontrolled