Etanercept and Infliximab Biosimilars Show Comparable Safety and No Increased Infection Risk

Patients treated with etanercept and infliximab biosimilars experience a similar risk of serious infections as those treated with the original brand-name drugs, according to a study published in BMC Rheumatology. This finding could provide patients with access to safe and more affordable treatment options for autoimmune diseases like inflammatory arthritis and inflammatory bowel disease (IBD).

Biologic drugs are increasingly used for managing autoimmune diseases, with real-world comparative studies focusing on the long-term safety of biosimilars and bio-originators. Despite global skepticism about biosimilar safety, previous studies have shown that infliximab biosimilars are effective and well-tolerated after switching, with no discontinuations or clinical changes within 6 months.

The study compared the occurrence of serious infections in Canadian patients with autoimmune diseases treated with etanercept or infliximab biosimilars versus their corresponding bio-originator from 2015 to 2019. Data were sourced from the National Prescription Drug Utilization Information System linked to the hospital Discharge Abstract Database.

Key findings include:

• 6583 individuals initiated etanercept, mostly women with a median age of 62, and about 10% had an inflammatory arthritis diagnosis.
• 7202 individuals initiated infliximab, half of whom were women with a median age of 45, with only 2% identified with inflammatory arthritis and 35% with IBD.
• Both cohorts had a median follow-up period of 2.2 years.
• More patients taking infliximab experienced hospitalization due to infection (7%) compared with patients taking etanercept (2%).
• Incidence rates for serious infection among infliximab users (30 cases per 1000 person-year [PY]) were higher than for etanercept (9 cases per 1000 PY).

No clear differences in the risk of serious infection were identified between biosimilar and bio-originator for both cohorts, even after adjusting for confounders. Higher infection risk was noted among both etanercept and infliximab groups following independent corticosteroid use, with older age being a risk factor for infection in etanercept initiators.

Study limitations include potential selection bias and variability in data elements across jurisdictions, which may affect data analysis and interpretation. The study underscores the importance of ongoing safety assessments to enhance understanding of biosimilar safety profiles and support evidence-based decision-making in managing chronic inflammatory diseases.