Infliximab Biosimilar Switch Due to Flare Risk: Monitoring Patients Is Crucial for Pharmacists

Switching from reference infliximab to biosimilars (infliximab-abda and infliximab-dyyb) for rheumatic diseases may lead to treatment delays and a higher risk of disease flares, particularly when the switch is mandated by insurance. | Image Credit: nick - stock.adobe.com

Infliximab biosimilars (infliximab-abda and infliximab-dyyb) may delay treatment after patients switch from the reference product, suggesting a possible risk factor for flaring/loss of disease control, according to a study published in the Journal of Pharmacy Technology.¹

Clinicians often treat rheumatic diseases like ankylosing spondylitis, psoriatic arthritis, rheumatoid arthritis, and uveitis, with the anti-tumor necrosis factor agent, infliximab. Over the past few years, the FDA approved 4 infliximab biosimilars. The FDA approved the first biosimilar, infliximab-dyyb, in April 2016, and they approved infliximab-abda in May 2017.² A few months later, the FDA approved infliximab-qbtx in December 2017, and it approved infliximab-axxq in December 2019.

Under the Biologics Price Competition and Innovation Act, a biosimilar product becomes interchangeable when it meets additional requirements that may produce the same clinical result as the reference product in any given patient, and pharmacists may substitute it for the reference product without prescriber input.¹ Currently, researchers have not gathered any interchangeable related data for infliximab.

Researchers conducted a retrospective analysis of data to evaluate the level of disease control after nonmedical switches from reference infliximab to biosimilars in patients with rheumatic disease. A total of 48 patients met the inclusion criteria, the majority were White women on reference infliximab products with a mean age of 59 years and a psoriatic arthritis diagnosis.

Several patients who remained on reference infliximab used a concomitant disease-modifying antirheumatic drug (DMARD), with methotrexate (55.2%) being the most common. Patients who switched to the biosimilar product also included some who used a concomitant DMARD, with methotrexate (63.2%) being the most common.

Primary insurance coverage varied between the 2 groups; commercial and Medicare coverage split almost evenly for patients in the infliximab reference group. Commercial and Medicaid serve as the primary coverages for the biosimilar group.

Researchers observed 60.4% of patients on the reference infliximab and 39.6% who switched to the biosimilar; 42.1% flared after switching to the biosimilar. All patients taking the biosimilar used infliximab-dyyb, and insurance mandated 89.5% to switch. Almost half of all patients (42.1%) experienced flares/loss of disease control after switching products. Most of the patients who experienced flares no longer use the biosimilar product (75%).

Two patients who flared after switching to a biosimilar (25%) experienced a delay in treatment because they attempted to receive prior authorization for reference infliximab. There were 75% of patients who reported the flare/loss of disease control within the first 4 months following the switch.

Overall, pharmacists play an important role in the multidisciplinary team approach to manage chronic inflammatory diseases. Pharmacists play an important role in the substitution of biosimilars and patient education surrounding their use.³ The role of pharmacists in this space will only continue to grow as more biosimilars gain FDA-approved interchangeability status. Researchers need future studies that directly compare the rate of flares/loss of disease control in rheumatology patients who remain on the reference product with patients who switch to a biosimilar.¹

The study design limited the results because of the small sample size and a single health network that included a primarily White population. Researchers expressed that they should label the study a pilot because it needs more data to draw meaningful conclusions. Ultimately, this may have indicated more flares than clinicians found relevant. Lastly, the health network’s formulary does not include every available infliximab biosimilar, which limits the findings of the study only to infliximab-abda and infliximab-dyyb.

“Pharmacists should follow patients who switch to biosimilar closely during the transition period, to provide education on biosimilars and to monitor for signs of flares/loss of disease control,” study authors concluded.

References

1. Jankowska M, Dessureault K, MacDougall J, Sowers M, Merchand M, Kennedy AG. Impact of nonmedical switches from reference infliximab to biosimilars on disease control within a rheumatology practice. J Pharm Technol. Published online December 21, 2024. doi:10.1177/87551225241308475

2. Biosimilar approvals. The Center for Biosimilars^®. January 7, 2025. Accessed June 4, 2025. https://www.centerforbiosimilars.com/biosimilar-approvals

3. Halpern L. As biosimilar substitutions become more common, education and patient counseling are paramount. Pharmacy Times^®. March 14, 2025. June 4, 2025. https://www.pharmacytimes.com/view/as-biosimilar-substitutions-become-more-common-education-and-patient-counseling-are-paramount