The study had no explanations for why patients stopped taking biosimilars or switched back to the reference product; authors said this merits further research.
Patients treated by US Veterans Healthcare Administration who tried an infliximab biosimilar after being treated with Remicade were almost 5 times more likely to switch to another innovator biologic—with most going back to the reference product.
Why this occurred is not known, however, and merits further study, according to authors writing in Current Medical Research and Opinion.
In the United States, getting patients and doctors comfortable with the idea of switching from an innovator or reference product to a biosimilar—or from one biosimilar to another—has proved far more challenging in rheumatology than has been the case in oncology, where alternative payment models may make switching a financial win for practices.
A provider survey by Cardinal Health, released just this week, found that rheumatologists were only half as likely as oncologists to switch a patient to a biosimilar if they were doing well on a reference product.
Infliximab, which can treat a variety of inflammatory conditions, was the subject of a 2018 study involving switching from the reference product, Remicade, to infliximab biosimilars among patients with inflammatory bowel disease (IBD). The study found that those who switched to the biosimilar had no increase in disease activity.
In the VA study, investigators used data from January 2012 through December 2019 to identify adults with rheumatoid arthritis (RA), psoriatic arthritis, plaque psoriasis, ankylosing spondylitis, or Crohn disease and ulcerative colitis (IBD), who were treated with Remicade or an infliximab biosimilar. Patients were required to have at least 5 treatments with Remicade in the 12 months prior to the index date to be evaluated.
Patients who had at least 12 months of observation time prior to the first treatment with Remicade were considered the primary population, and their data were assessed from the start of treatment with a biosimilar. Discontinuation was defined as switching to another biologic—including back to Remicade—or having more than 120 days between consecutive treatments.
Results showed a median duration of follow-up of 796 days among those who switched to a biosimilar (N = 838) and a median duration of follow-up of 337 days among those who continued the reference infliximab (N = 849). Those who switched products were 2.88 times more likely to stop taking the therapy and 4.99 times more likely to switch to a different innovator product (both P < .001).
Of the 653 patients who switched off the biosimilar to another innovator biologic, 594 switched back to the reference infliximab, Remicade. Results were similar among those with long-term and shorter-term Remicade use before the switch, and similar between those with RA and IBD.
Lin I, Melsheimer R, Bhak RH, et al. Impact of switching to infliximab biosimilars on treatment patterns among US veterans receiving innovator infliximab. Curr Med Res Opin. Published online February 7, 2022. https://doi.org/10.1080/03007995.2022.2037846