Rheumatoid arthritis (RA) affects 1 percent of the population worldwide and up to 40 percent of patients don't respond to current treatments. MBS2320, the drug being tested in this trial, represents a new approach to treating RA, with the potential not only to reduce levels of inflammation but to also directly prevent bone damage.The aim of this project is to test the safety, tolerability and efficacy of MBS2320 in patients with RA in combination with an existing treatment, methotrexate.

Rheumatoid Arthritis is a chronic autoimmune disease characterised by synovial inflammation and cartilage and bone degradation, leading to joint destruction and progressive disability.

The aim of the study is to evaluate the safety and tolerability of MBS2320 in patients with RA following chronic administration. In addition, the study aims to evaluate the effects of MBS2320 on measures of disease activity.

Inclusion Criteria:

• Male or female patients of childbearing or non-childbearing potential with with active RA, receiving stable once-weekly methotrexate
• between 18 and 75 years of age, inclusive.

Exclusion Criteria:

• Patients who are currently pregnant or breastfeeding.
• Patients who are being treated with biological or non-biological disease-modifying anti-rheumatic drug therapy.
• Patients with a history of any other inflammatory or arthritic disease in addition to RA that may interfere with the study.