Research Shows Some Swedish Patients Switching Away From Biosimilars

A recent study, sponsored by Pfizer and presented in a European League Against Rheumatism (EULAR) poster session earlier this month, found that a substantial number of patients who had switched treatment from reference etanercept to a biosimilar treatment switched back to the reference product after a short time.

The study’s authors sought to describe the position of the reference etanercept treatment within the Swedish biologics market for rheumatic diseases, including rheumatoid arthritis, before and after the launch of a biosimilar product.

The market share for each product was tracked using prescription data from the Swedish Prescription Registry (which covers 100% of prescriptions written in Sweden) for each month during the period between November 2015 and October 2016. The researchers tracked the switching dynamics of patients initiating the biosimilar treatment between April 2016 and October 2016, and measured the proportion of patients naïve to biologic treatment as well as the proportion of patients who had been treated with etanercept, adalimumab, and other biologic agents in the 12 months prior to initiating treatment with biosimilar etanercept.

The researchers found that, in the first 6 months after biosimilar etanercept was launched in the Swedish market, the market share of reference etanercept decreased from 40% to 31%. A total of 2439 patients were found to have initiated treatment with biosimilar etanercept, and of this group, 40.1% were naïve to biologic treatments, 48.3% had previously been treated with reference etanercept, 4.4% had been previously treated with adalimumab, and 7.2% had been previously treated with other biologics.

Among the group of patients who initiated biosimilar etanercept after having previously received its reference, 7% switched back to the reference after an average period of 43 days. Of the group who had previously received adalimumab, 6% switched back to treatment with adalimumab after an average of 57 days.

The researchers concluded that a switch from reference products to cheaper biosimilars is very likely to be a result of economic factors, however, the reasons for patients’ switching back to reference products is not clear. The researchers posit patient preference and clinical factors as possible reasons for such a return, but they state that longer-term studies will be necessary in order to confirm these preliminary findings.

The results of this study echo those of a previous study, also funded by Pfizer and conducted in Germany by the same research group, which found that 10% of patients who switched to biosimilar etanercept returned to treatment with its reference within 3 months. In the German study, 72% of patients who switched back to reference products returned to the same administration method they had used previously, suggesting that device type may have played a role.

As health systems contend with high prescription drug costs and patients find themselves with questions and concerns about switching, other European nations are turning to education programs to help keep patients on lower-cost biosimilars, though it remains to be seen whether such programs can prevent patients from switching back to reference products in the longer term.