A literature review published this past weekend in Drugs reaffirms what most parties interested in biosimilars suspect—that switching from a reference product to biosimilar is not a significant clinical concern. Biosimilar switching was not generally associated with poorer outcomes.
The study evaluated the results of 90 clinical studies comprising more than 14,000 patients with 14 diseases or conditions. The authors from Novartis (and its Sandoz subsidiary), the Oregon Medical Research Center, Rocky Mountain Cancer Centers, IBD Center of Humanitas Clinical and Research Hospital (Milan), and Avalere Health stated that “the great majority of the publications did not report differences in immunogenicity, safety, or efficacy [as a result of biosimilar switching]. The nature and intensity of safety signals reported after switching from reference medicines to biosimilars were the same as those already known from continued use of the reference medicines alone.” In addition, they reported, “Three large multiple switch studies with different biosimilars did not show differences in efficacy or safety after multiple switches between reference medicine and biosimilar.”
In this evaluation, the biosimilars tested included those for infliximab, epoetin, filgrastim, growth hormone (which has not been considered a biosimilar in the US), etanercept, and adalimumab. Infliximab was the subject of the majority of the clinical studies.
Of the 90 studies, two were outliers, suggesting potential safety issues associated with biosimilar switching. One was described as a 2016 retrospective study of a claims database from Turkey, which found a much higher discontinuation rate with the infliximab biosimilar compared with originator product in patients with rheumatoid arthritis.
The authors correctly note that the vast majority of the studies reviewed involved a single biosimilar switch, and that multiple switches may result in additional safety signals. However, they also point out that “patients have already been exposed to de facto multiple switches for many originator biologics when product quality attributes changed after one or more manufacturing process modifications were introduced.”
The question arises as to whether multiple switch studies are truly necessary outside of the requirement to prove interchangeability between a biosimilar and a reference product. There is a practical reason for doing so—the possibility (actually, the likelihood) of a patient enrolling in a new health plan one year, which covers the biosimilar but not the reference product. If the patient’s health plan changes once again one or two years later, that person may well be required to switch back to the reference product or yet another biosimilar.
This will heighten the importance of collecting real-world evidence and accumulating more experience outside of the clinical trial environment in terms of switching. Efforts such as those at the Biologics and Biosimilars Collective Intelligence Consortium should fill this gap over the next several years.