Background: Rheumatoid arthritis IRA) has been associated with significant morbidity and economic burden. Traditional pharmacotherapy (eg, NSAIDs, corticosteroids, disease-modifying antirheumatic drugs [DMARDs]) can be inadequate in controlling symptoms and disease progression. Abatacept is the first selective co-stimulation modulator approved by the US Food and Drug Administration for the management of RA. It is a fusion protein developed to modulate the T-cell co-stimulatory signal that is mediated through the CD28-CD80/86 pathway. Objective: The objective of this manuscript was to review the clinical pharmacology, pharmacokinetic and pharmacodynamic properties, tolerability, and clinical efficacy of abatacept. Methods: MEDLINE and International Pharmaceutical Abstracts were searched through June and May, respectively, of 2006 using the term abatacept or CTLA4-Ig. All prospective, randomized, Phase II and III trials, and their extension phases, were included. Results: Phase 11 and III clinical trials found that abatacept, at a dose of 10 mg/kg administered as a short IV infusion in combination with DMARDs, was associated with significant clinical benefit in patients with active RA. After 6 months of treatment, the American College of Rheumatology (ACR) criteria for 20% clinical improvement (ACR20 response) was attained in 41.9% to 67.9% of patients who received abatacept compared with 19.5% to 39.7% of patients who received placebo (P < 0.001). The percentages of patients achieving the ACR criteria for 50% and 70% clinical improvement (ACR50 and ACR70) were 20.3% to 39.9% and 10.2% to 19.8%, respectively, in the groups that received abatacept compared with 3.8% to 16.8% and 1.5% to 6.5%, respectively, in the patients who received placebo (P = 0.03 and P < 0.001). Additionally, abatacept was found to improve disease activity, physical function, pain, and health-related quality of life (HRQOL). The most commonly reported adverse effects associated with abatacept treatment were headache (18.2%), upper respiratory tract infection (12.7%), nasopharyngitis (11.5%), and nausea (11.5%). The incidences of infections and serious infections were higher in the group that received abatacept compared with patients who received placebo (53.8% vs 48.30% and 3.0% vs 1.9%, respectively; P not reported). No significant between-group differences in mortality were found. Conclusions: Available evidence suggests that abatacept was effective in controlling symptoms and improving HRQOL in patients with active RA and an inadequate response to DMARD therapy. The most commonly reported adverse effects associated with abatacept treatment were headache, upper respiratory infection, nausea, and nasopharyngitis. Additional trials are needed to determine the long-term safety profile of this agent and whether the clinical benefits of abatacept found in the current clinical trials will be sustained over time.
