- Subjects have been receiving csDMARD therapy >= 3 months and on a stable dose for >= 4 weeks prior to the first dose of study drug. The following csDMARDs are allowed: methotrexate (MTX), sulfasalazine, hydroxychloroquine, chloroquine, and leflunomide. A combination of up to two background csDMARDs is allowed except the combination of MTX and leflunomide.