Abatacept

Abatacept (Orencia) is the first in a new class of biologics known as selective costimulation modulators. It inhibits full activation of T cells and interacts with other cell types to affect additional mediators of the inflammatory cascade. The clinical efficacy of abatacept in patients with active rheumatoid arthritis, despite prior treatment with methotrexate or anti-tumor necrosis factor-alpha (anti-TNFalpha) therapies, has been investigated in two randomized, double-blind, placebo-controlled, multicenter, phase III trials of 6 or 12 months' duration. In these trials, patients received intravenous abatacept (fixed-dose regimen based on bodyweight) or placebo in addition to background disease-modifying anti-rheumatic drugs (DMARDs) other than anti-TNFalpha therapies. Relative to placebo, abatacept significantly improved signs and symptoms of disease assessed using American College of Rheumatology (ACR) 20, 50, and 70 criteria and specific improvement in physical function as measured by the Health Assessment Questionnaire Disability Index at 6 months and significantly slowed structural damage progression in joints at 12 months. Improvements in ACR 20, 50, and 70 response rates were maintained at the final assessment in the 12-month trial. Abatacept infusions were generally well tolerated. Acute infusion-related reactions occurred in 9% of abatacept and 6% of placebo recipients in phase III trials. Integrated safety data from five clinical trials showed that serious adverse events were reported in 13.6% of abatacept and 12.3% of placebo recipients and the incidence of serious infections was 3.0% and 1.9%. Abatacept administered with background biologic DMARDs appears to be less well tolerated than abatacept plus background nonbiologic DMARDs.