MADRID – judging from data drawn from registries in five Scandinavian countries in a study that evaluated retention rates after 1 year of therapy.
Bente Glintborg, MD, PhD, from the Center for Rheumatology and Spine Diseases, Rigshospitalet, Glostrup, Denmark, explains in a video interview that the indication provided to biosimilars for spondyloarthritis was extended from comparisons conducted in rheumatoid arthritis (RA).
In the absence of a randomized trial in spondyloarthritis, she suggested that this comparison might be the best opportunity to evaluate whether biosimilars perform as well as their biologic originator. This is an important aim based on the theoretical possibility that equivalence in RA does not translate into equivalence in other rheumatic conditions where biologics are indicated.
As she explains, 1,015 biologic-naïve patients initiating etanercept, a tumor necrosis factor (TNF) inhibitor, or a biosimilar were assessed at baseline and at the end of 1 year of therapy. The patients were enrolled in biologic registries maintained in Denmark, Finland, Iceland, Norway, or Sweden.
Retention rates at 1 year were numerically lower on etanercept than the biosimilars, but the difference was not significant (66% vs. 73%; P = 0.18). There also were no significant differences between the biosimilars and etanercept when disease activity was compared at 6 months.
Retention rates are a reasonable surrogate for both efficacy and tolerability based on the expectation that more patients would switch or discontinue agents in the event of lack of efficacy or unacceptable side effects, Dr. Glintborg said at the European Congress of Rheumatology.
In this interview, she notes that a similar study from the Nordic registries led by a coinvestigator also showed equivalent retention rates among spondyloarthritis patients when biosimilars and infliximab were compared at 2 years.
Dr. Glintborg received research support from Biogen, Pfizer, and Abbievie.