TRU-015, being developed by Trubion Pharmaceuticals Inc and Pfizer Inc, is an intravenously administered anti-CD20 IgG fusion protein for the treatment of rheumatoid arthritis. TRU-015 depletes B-cells from the peripheral blood in vitro, and can mediate complement-and antibody-dependent cellular cytotoxicity. TRU-015 was well tolerated in patients with rheumatoid arthritis in phase I and II clinical trials, and demonstrated an efficacy profile similar to other biological agents approved for rheumatoid arthritis. At the time of publication, phase II trials were ongoing in patients with rheumatoid arthritis. TRU-015 could represent a novel therapy for the treatment of rheumatoid arthritis, although the efficacy, safety profile and advantages of this compound compared with existing therapeutic options would need to be established in phase III trials. In addition, this agent also may be useful to the treatment of B-cell neoplasms and autoimmune diseases.