B cell targeted therapies

Although the precise pathogenesis of rheumatoid arthritis (RA) remains unclear, many cell populations, including monocytes, macrophages, endothelial cells, fibroblasts and B cells, participate in the inflammatory process. Ongoing research continues to evaluate the critical roles played by B cells in sustaining the chronic inflammatory process of RA. These findings have contributed to the development of targeted therapies that deplete B cells, such as rituximab, as well as inhibitors of B lymphocyte stimulation, such as belimumab. In a phase I trial, belimumab treatment significantly reduced CD20⁺ levels in patients with systemic lupus erythematosus. Phase I and phase II trials of rituximab found that rituximab plus methotrexate achieved significantly better American College of Rheumatology 50% responses for patients with RA than those patients receiving monotherapy with methotrexate. These clinical trial data present promising evidence for B cell targeted therapies as future therapeutic options for RA.