Comparing Efficacy and Safety of Etanercept and Biosimilars in Patients With Juvenile Idiopathic Arthritis

While etanercept is used more frequently in patients with juvenile idiopathic arthritis (JIA), the efficacy, safety, and occurrence of adverse events (AEs) were similar when compared with biosimilars, according to a study published in Open Rheumatology.¹ As etanercept is more expensive, investigators urge switching to biosimilars in pediatric patients whenever possible.

“For the last 20 years, etanercept [a tumor necrosis factor α (TNFα) inhibitor] has been successfully used in clinical practice,” investigators explained. “However, the high costs of biologics prevent their use as a first-line therapy despite their favorable efficacy and tolerability.”

Patents with JIA who started treatment after January 1, 2017, were included in the study using data collected from the German BIKER registry (Biologics in Pediatric Rheumatology Registry). Investigators focused on patients younger than 18 at baseline being treated with etanercept or with etanercept biosimilars, Benepali and Erelzi. Eligible participants either began treatment on etanercept, a biosimilar, or switched to a biosimilar during therapy. Disease activity and safety were compared as separate components.

Efficacy was measured using the Juvenile Arthritis Disease Activity Score (JADAS-10) and the Childhood Health Assessment Questionnaire Disability Index (CHAQ-DI). Disease activity was assessed at baseline and subsequent follow-ups and rated on a visual analog scale (VAS). Safety was determined by AE reports and discontinuation rates between the 2 groups were also analyzed.

A total of 348 patients were observed, with 293 in the etanercept cohort and 55 in the biosimilar cohort. Additionally, another 57 patients switched to a biosimilar from etanercept throughout their course of therapy. Patients who received a biosimilar skewed older and had received another biologic as a premedication.

There were no significant differences between patients receiving either etanercept or a biosimilar. Disease activity at baseline and at the final follow-up were similar in both groups. Additionally, disease activity remained the same in patients who were initially treated with etanercept before switching to a biosimilar.

AEs were most frequently cited as upper respiratory tract infections, reactions at the injection site, and gastrointestinal disorders. When AE rates per 100 patient-years were examined, the biosimilar cohort had a larger proportion of AEs when compared with the etanercept cohort, mainly due to local reactions (20% vs 6.8%, respectively). However, this did not impact adherence rates. AE frequencies per patient showed no significant difference in either group. Of the 19 severe AEs that required hospitalization, there were no significant differences in occurrence rate.

In the biosimilar cohort, 29.1% (n = 16) discontinued therapy, compared with 37.2% (n = 109) in the etanercept cohort. Reasons included remission, lack of efficacy, or experiencing AEs. In the group that switched to a biosimilar, 8 out of 57 patients discontinued treatment, with 50% of these achieving remission.

The much smaller number of patients in the biosimilar cohort limits the study and may reduce statistical reliability of the results. As many centers participate in the BIKER registry, there is a possibility that the reporting behavior of AEs may differ between rheumatologists and clinics. Another potential limitation is that patients were not randomly selected between the two cohorts and differed in their characteristics. However, the differences focused on age at therapy start and number of previously received biologics, so investigators are confident in the comparability of the groups.

“In accordance with the current literature, there are thus no medical concerns for increased use of the biosimilars Benepali and Erelzi,” investigators concluded. “Such increased use is particularly recommended considering the very high costs and growing inequality in access to treatment with biologics.”

Reference:

Thiele F, Klein A, Hospach A, et al. Efficacy and Safety of Etanercept Biosimilars Compared With the Originator for Treatment of Juvenile Arthritis: A Prospective Observational Study [published online ahead of print, 2021 Aug 27]. ACR Open Rheumatol. 2021;10.1002/acr2.11325. doi:10.1002/acr2.11325