Uptake of the First Biosimilar Infliximab Since Its Approval in South Korea

Abstract

Background/Purpose: Development of tumor necrosis factor (TNF) inhibitors has been a major advance in treatment of systemic inflammatory diseases, such as rheumatoid arthritis. While TNF inhibitors are highly effective in controlling systemic inflammation, their high cost limits their use in developing countries and raises concerns in the U.S. as well. The FDA is currently considering an application for a biosimilar version of infliximab, which has been available in South Korea since November 2012. Methods: Using the medical claims data (4/2009-3/2014) of the Korean Health Insurance Review and Assessment Service database, which includes the entire Korean population, we assessed the uptake of biosimilar infliximab. A segmented linear regression was used to examine utilization patterns of infliximab (the branded and biosimilar) and other branded TNF inhibitors (adalimumab and etanercept) before and after the introduction of biosimilar infliximab. The model included the number of claims by drug each month as the outcome variable, as well as an intercept and two slope terms that described the trend in use of TNF inhibitors per month before and after the introduction of biosimilar infliximab in November 2012. Results: We identified a total of 20,976 patients with mean age of 44 (SD 16) years who used adalimumab, etanercept, infliximab, or biosimilar infliximab during the study period. Since its introduction, there were 983 users of biosimilar infliximab. Among all the claims for any infliximab version, the proportion of biosimilar infliximab claims increased to 19% through 3/2014. The use of all TNF inhibitors increased significantly with the number of claims approximately tripling from 3,117 in April 2009 to 9,278 in March 2014. Prior to introduction of biosimilar infliximab, each month there were 33 (95%CI, 32-35) more infliximab claims, 44 (95%CI, 40-48) more etanercept claims, and 50 (95%CI, 47-53) more adalimumab claims (Figure). After the introduction of biosimilar infliximab, there was a significant change in the slopes with an additional increase in the use of both branded and biosimilar infliximab (9 claims/month, 95%CI, 2-17) and a decrease in the use of etanercept (-52 claims/month, 95%CI, -66 to -38) and adalimumab (-21 claims/month, 95%CI, -35 to -6). Conclusion: During the 15 months since its introduction in South Korea, one-fifth of all infliximab claims were for the biosimilar. Our results show that introduction of biosimilar infliximab may affect the use of other TNF inhibitors. These results suggest that an approved biosimilar infliximab product could have a major impact in the U.S., where about 40% of rheumatoid arthritis patients get treated with a biologic drug.