Studies Report on Switching, Tolerability, and Infection Risk With Biosimilar Infliximab

As the only anti—tumor necrosis factor therapies currently available to US patients with inflammatory diseases, biosimilars of infliximab are increasingly used to treat diseases like rheumatoid arthritis. While there are a wealth of data on real-world use of these products in territories like the European Union, less research has examined their use in the United States. During the American College of Rheumatology’s 2019 meeting, held this week in Atlanta, Georgia, researchers reported on the results of 3 studies that assessed real-world use of biosimilar infliximab in the US context.

First, a research team compared tolerability of infliximab biosimilars versus their reference product in terms of missed doses in both the induction and maintenance phases of treatment and discontinuation, defined as a 90-day gap without restarting therapy.¹

Using MarketScan data for the year 2017, they identified 318 patients who used a biosimilar, and 206 of these patients had switched from the reference infliximab. Among the 92 new starts who had 2 or more months of follow-up, the frequency of missed doses during induction was 22%. This was similar to the 25% frequency of missed doses for new users of the innovator infliximab, say the authors. They note that they were unable to determine whether discontinuation differed between the groups.

A second study, also using MarketScan data for the year 2017, assessed risk factors associated with serious infections among new users of either biosimilar or reference infliximab.² The team identified 2584 patients who started taking the reference product and 92 who started taking a biosimilar.

Among these patients, there were 115 infections that resulted in hospitalization; infection rates were 5.5 (95% CI, 1.4-22.1) for users of the biosimilar versus 8.5 (95% CI, 7.0-10.3) for users of the originator product. Age-adjusted Charlson Comorbidity Index scores, past hospitalized infections, and glucocorticoid use were all associated with a risk of hospitalized infections.

These reassuring findings aside, another research team reported that patients who switch from originator to biosimilar infliximab are more likely to switch to a different biologic agent (or back to the reference product) compared with patients who remain on the originator drug.³

Using Symphony Health Solutions’ data, the researchers identified patients with 2 or more claims for an inflammatory disease and 1 or more claims for an infliximab product. Patients included in the analysis had been receiving reference infliximab for 5 or more claims over 12 months, and patients who switched were matched 1:3 with those who continued to receive the reference.

After matching, 823 switchers were included, as were 2469 patients who continued to receive the reference. Over a mean (SD) period of 350 (197) days for switchers and 321 (214) days for nonswitchers, 25.6% of switchers and 9.1% of nonswitchers changed therapy to a different branded biologic agent. Among the biosimilar switch group, 82.5% of those who switched their therapy changed back to the reference infliximab.

The mean (SD) time to switch to another agent was 142 (110) days for the biosimlar switch group and 174 (142) days for the nonswitch group.

Notably, the data used in this evaluation did not include reasons for switching or discontinuation, so further research is warranted.

References

1. Moura CS, Curtis J, Choquette D, et al. Recent use, missed doses and discontinuation of infliximab in a population-based cohort: comparisons of biosimilar and originator exposures. Presented at: The American College of Rheumatology Annual Meeting, November 8-13, 2019; Atlanta, GA. Abstract 203.

2. Moura CS, Curtis J, Choquette D, et al. Risk factors associated with serious infections among users of biosimilar and originator infliximab therapies. Presented at: The American College of Rheumatology Annual Meeting, November 8-13, 2019; Atlanta, GA. Abstract 202.

3. Emond B, Sadik K, Lafeuille MH, et al. Switching patterns among patients with chronic inflammatory diseases switching to an infliximab biosimilar or remaining on originator infliximab (Remicade). Presented at: The American College of Rheumatology Annual Meeting, November 8-13, 2019; Atlanta, GA. Abstract 1115.