Stable Treatment Persistence in RA After Etanercept Biosimilar Introduction in Australia

Although Australia has one of the highest global rates of rheumatoid arthritis (RA), with an estimated 2000 cases per 100,000 people, the country has been an early adopter of biosimilars to help reduce costs and expand patient access to biologic therapies.¹

A new nationwide real-world study published in Pharmaceutical Medicine assessed whether the availability of the etanercept biosimilar Brenzys, listed on Australia’s Pharmaceutical Benefits Scheme (PBS) in 2017, influenced treatment persistence among people living with severe RA.²

Australia's adoption of etanercept biosimilars enhances access to rheumatoid arthritis treatments, maintaining treatment persistence and patient care quality. | Image credit: Manual - stock.adobe.com

Reference etanercept, marketed as Enbrel, has been a cornerstone biologic disease-modifying antirheumatic drug (bDMARD) for patients with severe RA since 2003. With the biosimilar Brenzys introduced in 2017, policymakers and clinicians sought evidence on whether integrating a biosimilar into practice would affect long-term treatment effectiveness, as measured by treatment persistence. Clinical trials had already established biosimilar efficacy and safety, but their short duration and selective populations limited insights into real-world use.

“Concerns have been raised among clinicians about whether biosimilars perform as well as originators outside of trial settings,” study authors noted. “Our study provides reassuring evidence that biosimilar entry has not negatively affected treatment continuity in routine care.”

Researchers conducted a retrospective cohort study using national PBS claims data linked to the National Death Index. Adults aged 18 years and older who initiated etanercept for severe RA between April 2013 and March 2022 were included. Participants were stratified into:

• Historical cohort (2013-2016): 4461 individuals who started etanercept before biosimilar entry
• Contemporary cohort (2018-2022): 5773 individuals who began therapy after the biosimilar was listed

The analysis excluded those using the 25 mg/mL formulation, as no biosimilar existed for that strength. Approximately 40% of contemporary cohort patients were estimated to have received the biosimilar.

Baseline characteristics showed the contemporary cohort was slightly older (mean age, 59.0 years vs 55.9 years) and had a higher proportion of men (27.8% vs 24.7%). Both groups had high comorbidity scores, reflecting the burden of chronic disease in this population. Most patients received conventional synthetic DMARDs (csDMARDs) prior to etanercept initiation, although this was somewhat lower in the contemporary group (85.8% vs 90.4%).

Treatment persistence was similar across groups:

• Median time to discontinuation: 10.0 months (95% CI, 9.7-10.6) in the contemporary cohort vs 10.6 months (95% CI, 10.0-11.4) in the historical cohort (P = .08)
• Retention at 12 months: 46.3% in the contemporary group vs 47.7% in the historical group
• Retention at 24 months: 32.2% vs 33.8%, respectively
• Adjusted hazard ratio: 1.00 (95% CI, 0.96-1.05), showing no significant differences in discontinuation risk

Subgroup analyses of older adults (≥ 65 years) and biologic-naïve individuals mirrored the main findings. For biologic-naïve patients, median persistence was slightly longer (11.7-12.7 months) but again showed no meaningful difference between cohorts.

Drug utilization after discontinuation was also consistent between groups. Nearly half of patients transitioned to another bDMARD, most often adalimumab, and about 19% reinitiated etanercept within 6 months.

This investigation is notable as the first population-level analysis in Australia using national claims data to evaluate real-world treatment persistence with etanercept before and after biosimilar entry. The large sample size of more than 10,000 patients strengthens the reliability of results.

However, several limitations were acknowledged. PBS data do not capture brand names, preventing direct comparisons between originator and biosimilar users. Thus, the contemporary cohort included a mix of both products. Additionally, the claims database lacked clinical measures of disease activity, laboratory markers, or reasons for treatment discontinuation, limiting insights into patient-level decision-making. Evolving treatment guidelines over time could also have influenced prescribing patterns.

These findings suggest that biosimilar entry has not disrupted treatment continuity among people living with severe RA in Australia. “Rather than adversely impacting patient care, biosimilar availability supports broader access to effective therapies at a reduced cost,” the authors concluded. They emphasized that future work should focus on brand-specific comparisons and safety outcomes to inform clinical and policy decisions.

The Australian experience offers timely reassurance for health care systems worldwide considering strategies to expand biosimilar adoption. Real-world data show that the introduction of the etanercept biosimilar has maintained stable treatment persistence.

Reference

1. Yiu CH, Ianni BD, Day RO, Raubenheimer J, Lu CY. Treatment persistence in rheumatoid arthritis before and after etanercept biosimilar introduction: a nationwide Australian real-world study. Pharm Med. 2025;39:369-381. doi:10.1007/s40290-025-00577-8

2. Treatment persistence in rheumatoid arthritis before and after etanercept biosimilar introduction: a nationwide Australian real-world study. 2025;39(5):369-381. doi:10.1007/s40290-025-00577-8