[Efficacy and adverse events of etanercept in patients with rheumatoid arthritis: reports of postmarketing surveillance in Japan].

Etanercept is a soluble tumor necrosis factor (TNF) receptor fusion protein that binds and inactivates TNF. Since etanercept was just approved in January 2005 in Japan, a strict postmarketing surveillance has been undertaken. In this trial, initial 3,319 patients with rheumatoid arthritis were collected, and the adverse events and efficacy of etanercept were evaluated. The frequency of adverse events were found in 30.9 %, among total patients particularly severe adverse effects in 4.2 %. Among severe adverse events, 83 patients experienced infection. They included 25 patients with bacterial pneumonia. Interstitial pneumonia, pneumocystis jiroveci and tuberculosis were observed in 11 cases (0.3 %), 5 cases (0.2 %) and 2 cases (0.1%), respectively. Patients who received etanercept had a more rapid rate of improvement in disease activity determined by DAS 28 ESR and DAS28 CRP. These improvements continued through 24 months of etanercept exposure. Using the analysis of EULAR response criteria, the good or moderate response in the DAS 28 ESR response and DAS 28 CRP was found in more than 80% of patients with RA.