Biologic agents for the treatment of rheumatoid arthritis

The therapeutic potential of costimulatory blockade with CTLA4Ig in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory disorder characterised by joint inflammation and destruction. Controversy exists regarding the significance and exact role of activated T cells in RA. CTLA4Ig is a soluble fusion protein (cytotoxic T lymphocyte-associated antigen 4 fused to the heavy chain constant region of human IgG1), which represents the first in a new class of agents called costimulation blockers. By blocking the second signal required for optimal T-cell activation, CTLA4Ig has demonstrated efficacy in a variety of spontaneous and induced animal models of autoimmunity. A Phase II clinical study in RA showed CTLA4Ig was efficacious with an acceptable safety profile. These results suggest that activated T cells may be important in RA pathogenesis and that costimulation blockade may be a novel therapeutic approach for this disorder.

Therapy of systemic vasculitis

The systemic vasculitides represent a highly heterogeneous and complex set of disorders primarily mediated via immunologic mechanisms. Standard therapy of these diseases includes the use of glucocorticoids without the use of additional cytotoxic agents. Recent long term follow-up investigations of patients treated with combined therapy has revealed an alarming incidence of treatment-related toxicity. Currently recommended therapeutic regimens are designed to minimize such toxicity while maintaining disease control. New therapeutic agents with greater disease specificity and lower toxicity are now being examined.