Zenas ZN Yiu, MBChB | Credit: personalpages.manchester.ac.uk

Biosimilar use rose but varied substantially around both the United Kingdom and the Republic of Ireland, with adalimumab biosimilars showing the highest uptake rate versus other tumor necrosis factor-α inhibitors (TNFi) drugs, according to new findings.¹

These findings were the result of a recent study authored by Zenas ZN Yiu, MBChB, from the National Institute for Health and Care Research Manchester Biomedical Research Centre in the United Kingdom.

In the dermatology field, TNFi treatments were noted by Yiu and colleagues as having revolutionized the moderate-to-severe psoriasis treatment landscape.² Consequently, trends in use were seen as important for researchers to understand.

“Following patent expiration of originators, TNFi biosimilars became available, presenting the opportunity for significant reductions in drug costs,” Yiu and colleagues wrote, explaining the uptake in biosimilar use’s origins.

Background and Findings

The investigators conducted an observational cohort study, gathering data from the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR). The BADBIR is a national pharmacovigilance register for patients with psoriasis that are on systemic treatments.

The investigators also noted that they used the BADBIR to analyze trends over time in biosimilar uptake in the various regions of the UK and Ireland. Their study assessed patients who had been found to switch from originator drugs to biosimilars and patients who initiated treatment with biosimilars.

The research team’s cohort of switchers they examined included patients who were on originator etanercept, infliximab, and adalimumab when their patents expired. These patients were followed until October of 2021.

The factors associated with switching from originator drugs to biosimilars were also evaluated by the researchers using a multivariable Cox regression model. They also investigated factors associated with initiating biosimilar treatment using a logistic regression model.

The investigators analyzed 4202 patients in the end, specifically those who were using infliximab, etanercept, or adalimumab. Over time, the proportion of patients who were found to have switched from the originator drug to the biosimilar saw increases.
After 3 years, the switching rates were reported to be 14.8%, 23.6%, and 66.6% for infliximab, etanercept, and adalimumab, respectively. The team found these rates varied across regions, ranging from 0% to 43.7% for infliximab, 0% to 40.4% for etanercept, and 12.5% to 84.3% for adalimumab.

Among the 528 patients who were in the adalimumab-naïve group, 67.8% had started on biosimilars. The investigators found that men and patients with lower Psoriasis Area and Severity Index (PASI) scores at cohort entry ended up being more likely to either switch from the originator drug to the biosimilar or to initiate treatment with a biosimilar.

“In conclusion, the uptake of biosimilars increased over time and varied considerably across the UK and RoI; adalimumab had the highest biosimilar uptake rate compared to other TNFi drugs,” the team wrote.

References

1. ^{Duc Binh Phan, et al. Uptake of tumour necrosis factor-alpha inhibitor biosimilars for psoriasis: A drug utilisation study from the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR). British Journal of Dermatology. Published April 5, 2023. Accessed April 11, 2023. https://doi.org/10.1093/bjd/ljad107.}
2. ^{Prignano F, Choi J, Pieper B, Iversen L. Anti-tumor necrosis factor agents in psoriasis: addressing key challenges using biosimilars. Expert Opin Biol Ther. 2021 Jan;21(1):75-80. doi: 10.1080/14712598.2020.1812576. Epub 2020 Sep 4. PMID: 32886008.}