Prevalence of switching from two anti-TNF biosimilars back to biologic reference products in Germany .

Biosimilars are becoming more and more important for the treatment of many diseases. However, it is not understood how they are tolerated. Our aim was to analyze the behavior of switching from two anti-TNF biosimilars back to biologic reference products in German patients. Patients switching from etanercept reference to an etanercept biosimilar between February 2016 and December 2017 and those switching from the infliximab reference product to an infliximab biosimilar between February 2015 and December 2017 were included in the study (index date). The main outcome of this study, the rate of switching from these two biosimilars back to reference products, was analyzed using Kaplan-Meier curves. A multivariate Cox regression model was used to predict the switch-back behavior. A total of 2,956 patients were included in this study. After 3 months, 14.7% and, after 12 months, 30.2% of them were switched back from a biosimilar to the reference product. Sex, age, physician specialty, and co-therapy were not significantly associated with this switch. Almost one third of the patients treated with one of two biosimilar drugs after previous biologic therapy are switched back to reference products in Germany.