Infliximab Biosimilars Not Linked to Worsened Infection Risk

Despite a history of concern over safety outcome disparities among patients switching to from a reference biologic product to a biosimilar, new research from Canada suggests at least one biologics’ biosimilars are not associated with increased risk of serious infections.¹

In new research presented in an abstract presented at the International Conference on Pharmacoepidemiology and Therapeutic Risk Management (ICPE) Annual Meeting this year, a team of Canada-based investigators reported findings showing patients administered an infliximab biosimilar did not report significantly different rates of serious infections relative to patients maintained on reference infliximab (Remicade). Though the findings are limited in the trial methodology, they provide further reassurance that an infliximab biosimilar may not predispose patients to greater serious adverse event risks.

Infliximab is a tumor necrosis factor (TNF) inhibitor investigated for and marketed to treat autoimmune diseases including Crohn’s disease and rheumatoid arthritis. Despite its targeted efficacy among patients with chronic disease, the agent has historically been linked to an increased risk of serious infections among treated patients with conditions including plaque psoriasis.²

“Infection is an important safety concern for biologics, and relatively few real-world data analyses have compared biosimilar versus bio-originator agents,” the investigation team, led by Marina G. Birck, PhD, MSc, of the Research Institute of the McGill University Health Centre, wrote regarding their study.¹

Birck and colleagues conducted their analysis of serious infection risk relative to reference infliximab product and its biosimilars via data from the Canadian National Prescription Drug Utilization Information System. The database contains pan-Canadian claims information regarding dispensations paid from public drug programs and its associated with the Hospital Discharge Abstract Database and National Ambulatory Care Reporting System.

The analysis included adults aged ≥18 years old who initiated infliximab between 2015 – 2019. Investigators conducted follow-up from treatment initiation through discontinuation—defined as no dispensation for ≥90 days—or end of trial period. They defined serious infections via ICD-10 diagnostic codes in instances when patients are first hospitalized.

Patients were stratified as either initiators of biosimilar or originator infliximab and were compared with Cox regression models adjusted for patient demographics, treatment history, region and timing of care.

The team identified 2305 new users of infliximab biosimilars and 5107 new users of originator infliximab. Median patient age at initiated care was 45 years (IQR, 28 – 62).

Investigators observed a rate of 3.1 serious infection adverse events per 100 person-years across both cohorts (95% CI, 2.7 – 3.3). The rate of events were consistent among patients initiating infliximab biosimilars (3.6 per 100 patient-years; 95% CI, 3.0 – 4.3) or originator (3.1 per 100 patient-years; 95% CI, 2.8 – 3.4). The risk of serious infection was slightly lower among patients receiving originator infliximab compared to those receiving biosimilars; however, the difference was statistically insignificant (adjusted hazard ratio, 0.97; 95% CI, 0.77 – 1.21).

“In this real-world dataset, we were unable to identify clear differences in serious infectious comparing infliximab biosimilar and infliximab originator initiators,” the team concluded. “Limitations include inability to control for residual confounders (e.g., disease severity), potential outcome misclassification, and selection bias.”

Reference

1. ^{Birck MG, Lukusa L, Choquette D, Boire G, et al. Comparison of serious infections between biosimilar and bio-originator initiators in Canada: Population-based analyses. Presented at: Utilization and patient characteristics for the originator and biosimilar trastuzumab products in the United States. International Conference on Pharmacoepidemiology and Therapeutic Risk Management (ICPE) 2023 Annual Meeting. Halifax, Canada. August 25 – 27, 2023.}
2. ^{Yiu ZZN, Ashcroft DM, Evans I, et al. Infliximab is associated with an increased risk of serious infection in patients with psoriasis in the U.K. and Republic of Ireland: results from the British Association of Dermatologists Biologic Interventions Register (BADBIR) [published correction appears in Br J Dermatol. 2019 Sep;181(3):646]. Br J Dermatol. 2019;180(2):329-337. doi:10.1111/bjd.17036}