Phase 3 study of ocrelizumab for rheumatoid arthritis (RA)

Genentech and Biogen Idec announced positive results from their Phase 3 study (STAGE) of the investigational humanized anti-CD20 monoclonal antibody ocrelizumab given in combination with methotrexate (MTX). This study was an international, randomized, multicenter, three-arm, parallel-group, placebo controlled study in 1,015 patients with active rheumatoid arthritis (RA) with an inadequate response to prior treatment with MTX. The study consisted of a 48-week double-blind treatment period and study extension period of at least 48 weeks. Patients received two courses at six-month intervals of either one of two different doses of ocrelizumab or placebo by intravenous infusion on Day 1 and Day 15, with weekly MTX as a background therapy. This study met its primary endpoint of improving signs and symptoms (as measured by American College of Rheumatology or ACR20 response) in RA patients who had an inadequate response to MTX at both 24 and 48 weeks.  

Ocrelizumab is an investigational humanized monoclonal antibody that binds to and eliminates CD20-positive B-cells. It selectively binds to a particular protein – the CD20 antigen – on the surface of B-cells, which are believed to play a critical role in immunologic diseases. Stem cells (B-cell progenitors) in bone marrow lack the CD20 antigen, allowing healthy B-cells to regenerate after treatment and eventually return to normal levels.

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