A human IgG4 monoclonal antibody against B-cell activating factor (BAFF), with potential immunomodulating and antineoplastic activities. Tabalumab binds to and inhibits the activity of both soluble and cell surface-bound BAFF. This may reduce the activity, proliferation and survival of B-cells. A dysregulated expression of BAFF, a member of the tumor necrosis factor (TNF) family of proteins, is often seen in certain autoimmune diseases and certain cancers, and may promote B lymphocyte activation, proliferation and survival.