On May 23, at The International Society for Pharmacoeconomics and Outcomes Research’s 22nd Annual International Meeting in Boston, researchers presented new findings concerning switching between Amgen’s biological agent etanercept (Enbrel) and its first biosimilar product in the German marketplace.
“Preliminary Real World Data on Switching Dynamics Between Etanercept and its Recently Marketed Biosimilar Counterpart,” a study sponsored by Pfizer and conducted by researchers from University Medicine Berlin, Pfizer, and QuintilesIMS, was designed to provide initial data concerning market penetration of the first etanercept biosimilar (EtnBS). The study sought to evaluate the switching dynamics between etanercept and EtnBS in real-world clinical settings. Following its launch in Germany in February 2016, EtnBS has been used by rheumatologists as an alternative to etanercept, a tumor necrosis factor inhibitor used in the treatment of certain rheumatic diseases.
The study considered 5349 patients, identified retroactively through the German Longitudinal Prescriptions database (which represents approximately 60% of the statutory health insurance market), who were initiating EtnBS therapy. Immediately prior to treatment with EtnBS, 48% of the study’s patients had not been treated with a biological agent, 36% had been treated with etanercept, and 16% had been treated with another biological agent. Of the patients who had been treated with etanercept previously, the majority had approximately 3 years of treatment prior to switching to the biosimilar. Among the patients previously treated with etanercept, 53% administered the product using injection pens, and 47% used pre-filled syringes.
The researchers found that the use of EtnBS has been steadily increasing since the product’s 2016 launch in the German marketplace, and that EtnBS reached a market share of 10% in March 2017 (compared with a 31% market share for the originator product).
However, the researchers found that, among patients who changed their treatment from etanercept to EtnBS, 10% switched back to the original product within a 3-month period. Of those patients who returned to etanercept treatment, a large proportion (72%) returned to using the same administration method that they had employed previously. The study’s authors suggest that the type of device used may have influenced the patients’ decisions to switch back to etanercept.
When considering all biological agents available (including adalimumab, rituximab, and infliximabBA, among others), the researchers found that 8% to 16% of patients initiating treatment with EtnBS changed to another biological agent within a 3- to 4-month period. The percentage of patients who switched from EtnBS was higher among those patients who had been treated with biological agents prior to initiating EtnBS.
The study’s authors caution that longer-term studies will be necessary to confirm these preliminary findings, and to better understand why some patients choose to return to treatment with reference products after treatment with biosimilar products. Understanding these reasons may hold the key to increasing uptake of biosimilars and controlling the cost of treating diseases using biological agents.