This study consists of a Double-blind , placebo controlled, and parallel group part with eligible patients enrolled into a 24 week Double-Blind Period, and randomized in a 1:1 ratio to receive ofatumumab (700mg x 2 infusions) or placebo ( saline x 2 infusions) in addition to their background methotrexate treatment. Patients who completed the 24 week Double-Blind period without receiving rescue DMARD treatment will be eligible to proceed into the 120 week Open-Label Period to receive repeat treatment courses with ofatumumab. In the Open-label Period ofatumumab treatment courses will be given at individualized time intervals only if a clinical response has been achieved following the previous treatment course, and followed by a subsequent worsening in disease activity . Patients who have completed the Open-Label Period or have withdrawn will enter a maximum 2 year Follow-up Period, or until their Bcells return to normal or to baseline levels, whichever occurs earlier.
