The purpose of this study is to assess whether BMS-817399 in combination with Methotrexate is effective in treating moderate to severe rheumatoid arthritis.

Inclusion Criteria:

• Male or female subjects, 18 years of age or older, with rheumatoid arthritis (RA) for at least 6 months prior to screening
• Subjects must have a tender joint count of at least 6 (28 joint count), swollen joint count of at least 6 (28 joint count) at screening. All subjects must have clinical evidence of synovitis in one hand/wrist at screening
• Serum C-reactive protein (hsCRP) above upper limits of normal at screening
• Subjects must have been treated with and tolerated Methotrexate (MTX) therapy at a weekly oral or parenteral dose ≥ 10 mg for ≥ 4 months prior to screening. Dose must be stable, with no change in route of administration, for ≥ 6 weeks prior to randomization. A MTX weekly dose as low as 7.5 mg is permitted if intolerance to doses ≥10 mg has been documented in the subject's medical history
• Subjects must be receiving folic acid, folinic acid, or leucovorin supplementation at a stable dose for at least 4 weeks prior to randomization
• Subjects who were previously treated with up to two tumor necrosis factor α (TNF-α) inhibitors
• If taking antimalarials (e.g. hydroxychloroquine or chloroquine), subject must have been on a stable dose for ≥ 4 months prior to randomization
• If taking non-steroidal anti-inflammatory drugs (NSAIDs), subjects must have been on stable doses for ≥ 2 weeks prior to randomization
• If taking oral corticosteroids, daily doses must be ≤ 10 mg/day of prednisone or equivalent and stable for ≥ 4 weeks before randomization
• Subject is willing to participate to the study and has signed the informed consent prior to undergoing any screening procedures
• Women of childbearing potential (WOCBP) and men must agree to use at least two acceptable methods to avoid pregnancy for the entire study period and until 60 days (for women) and 90 days (for men) after the last dose of BMS-817399. WOCBP must have a negative urine pregnancy test at screening, randomization and at scheduled visits throughout the study

Exclusion Criteria:

• Arthritis onset prior to 16 years of age or subjects with documented juvenile RA

• Subjects who are bed- or wheelchair-bound

• Subjects with other autoimmune diseases or arthritis syndromes

• Women who are pregnant, breastfeeding or with a positive pregnancy test at screening or prior to randomization

• Subjects who have any condition that could impact upon the absorption of study drug (i.e., gastric stapling, duodenal surgery, malabsorption syndrome)

• Subjects with a history of, or a concurrent severe, progressive, or uncontrolled disease (other than RA) that in the opinion of the investigator might place the subject at unacceptable risk for participation in this study

• Subjects who have present or previous (last 5 years) malignancies, except history of cured squamous or basal skin cell carcinoma or cured breast or cervical cancer

• Subjects at risk for tuberculosis (TB) or with evidence of TB clinical history, chest X rays or tuberculin skin test

• Subjects with evidence of active or latent bacterial or viral infections (including human immunodeficiency virus); Positive blood screen for hepatitis B surface antigen or hepatitis C antibody

• Subjects with any serious bacterial infection within the last 2 months, unless treated and resolved with antibiotics

• Subjects who have clinically significant drug or alcohol abuse or known cirrhosis including alcoholic cirrhosis

• If a subject has received any of the following treatments, the indicated washout period prior to randomization must be followed:

  1. Oral or injectable azathioprine, gold, D-Penicillamine, cyclosporine, anakinra, etanercept, parenteral or intra-articular corticosteroids: 30 days
  2. Leflunomide: 6 months unless an active washout with Cholestyramine has been performed
  3. Mycophenolate mofetil, cyclophosphamide, tacrolimus or other immunosuppressant: 3 months
  4. Adalimumab, Infliximab, Golimumab, Certolizumab pegol, Abatacept or Tocilizumab: 60 days
  5. Rituximab or any B-cell depleting agent: 1 year

• Use CYP3A4 inhibitors or inducers during the study

• Subjects with alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≥ 1.5x upper limit of normal (ULN), total bilirubin ≥ 1.4x ULN, estimated glomerular filtration rate (GFR) < 50 mL/min/1.73m2, hemoglobin < 10.0 g/dL, white blood cell count < 3,500/mm3, absolute neutrophil count < 1,700/mm3 or platelets < 125,000/mm3