Modulation of T-Cell Co-Stimulation in Rheumatoid Arthritis

Rheumatoid arthritis (RA), characterized by progressive joint destruction, deformity, disability and impaired quality of life (QOL), is a prevalent autoimmune disease affecting 1% of adults in the US. The goal of therapy in patients with RA is to arrest the disease and to achieve remission by preventing or controlling joint damage, preventing loss of function and providing pain relief, thereby improving QOL. Non-biological disease-modifying antirheumatic drugs (DMARDs) have been the mainstay of early intervention in RA, of which methotrexate has been used most frequently. However, in the long term, patients treated with non-biological DMARDs (including methotrexate) may experience joint deterioration and subclinical inflammation even after clinical remission, emphasizing the need for alternative therapies. Several biological therapies, such as anti-tumour necrosis factor (TNF)-α agents, have been developed in the last decade and may be used either as monotherapy or in combination with non-biological DMARDs. Although anti-TNFα therapy is generally associated with an improvement in symptoms of RA, some patients may experience inadequate response to or may not tolerate these agents. The new biological agent abatacept, a recombinant protein consisting of the extracellular region of the human cytotoxic T-lymphocyte-associated antigen (CTLA)-4 receptor fused to the constant fragment (Fc) region of IgG1, binds to the CD80/CD86 molecules on antigen-presenting cells and modulates T-cell activation. Clinical trials have shown that abatacept is effective in reducing disease activity, structural joint damage and improving QOL in patients with RA who had inadequate response to prior methotrexate or anti-TNFα therapy. Pooled analysis of these trials showed that abatacept was also generally well tolerated in these patients. Thus, abatacept therapy may be an option for the treatment of RA in patients who have had an inadequate response to prior DMARD therapy.