Abatacept
Abatacept, which modulates T-cell activation, was shown to increase the rate of serious infection in clinical trial data at 12 months, but not in a meta-analysis of five trials. One observational study has reported that the rate of infection was lower with abatacept than with rituximab, infliximab, etanercept or adalimumab, but the large AIM (Abatacept in Inadequate responders to Methotrexate) trial reported that the risk of infection with abatacept is similar to that seen with TNFi. A recent retrospective analysis of a US claims database found that for 4332 RA patients switching to a second biologic, the risk of serious infection was not significantly different among patients switching to rituximab, abatacept, etanercept and adalimumab but significantly higher for those switching to infliximab. Pooled data from eight trials of i.v. abatacept in RA found no difference in the infection rate between abatacept-treated and placebo-treated patients during the short-term (<12 month) analysis, which included 2331 patient years' exposure. In the analysis of both short-term and open label extension studies, incorporating 12 132 patient years' exposure, the rate of serious infection remained consistent with increasing exposure at 2–3 per 100 patient years.