Efficacy and Safety Study of MP-435 in Combination With Methotrexate (MTX) in Patients With Rheumatoid Arthritis

A Multicenter Randomized, Double-blind, Placebo-controlled Study of MP-435 in Combination With MTX in Patients With Rheumatoid Arthritis - Exploratory Study

The purpose of this study is to determine the Efficacy, Safety, and Pharmacokinetics of MP-435 administered for 12 weeks in subjects with rheumatoid arthritis (RA) on stable doses of Methotrexate.

Inclusion Criteria:

• Subjects with a diagnosis of RA according to the diagnostic criteria of the American College of Rheumatology (ACR) (revised in 1987) for at least 6 months.
• Subjects who inadequately response for stable dose of MTX.

Exclusion Criteria:

• Patients with Class IV functional activity by the Steinbrocker's scale.
• Patients who have received a biological agent in the past.
• Patients who have other rheumatic diseases, or who have other diseases with joint symptoms.
• Patients with severe or uncontrolled endocrine, psychiatric, cardiac, hematological, pulmonary, hepatic, kidney, gastrointestinal, or thyroid disease.