Treatment Retention Rates Lower in Patients Switching From Originator to Biosimilar Etanercept

Switching from originator etanercept to biosimilar etanercept (SB4) had no negative effect on disease activity at 3 months.

Switching from originator etanercept to biosimilar etanercept (SB4) had no negative effect on disease activity at 3 months in patients with inflammatory arthritis, according to study results published in the Annals of the Rheumatic Diseases. Results also indicated lower adjusted treatment retention rates in patients who switched from originator etanercept to SB4.

The study included participants with rheumatoid arthritis, psoriatic arthritis, and axial spondyloarthritis who were treated with originator etanercept 50 mg. The researchers compared clinical characteristics and treatment outcomes in participants who switched to SB4 (switchers) and patients who maintained the originator (non-switchers). They compared retention rates between participants and those of a historic cohort of originator etanercept-treated patients.

Of 2061 originator etanercept-treated participants, 79% (n=1621) switched to SB4. In participants who switched, there was no change in disease activity 3 months after switching.

The researchers calculated 1-year adjusted retention rates. They found a retention rate of 77% (95% CI, 72%-82%) for non-switchers, 83% (95% CI, 79%-87%) for switchers, and 90% (95% CI, 88%-92%) for the historic cohort.

The results indicated that participants who were not in remission had lower retention rates compared with participants in remission, both among switchers (crude hazard ratio [HR], 1.7; 95% CI, 1.3-2.2) and non-switchers (crude HR, 2.4; 95% CI, 1.7-3.6).

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During the follow-up period, 7% of switchers (n=120) switched back to originator etanercept. The researchers found that the clinical characteristics of this group were similar to those of switchers. The reasons for switching were mainly subjective.

“These real-world data indicate that switch outcomes in routine care are affected by non-specific drug effects and patient-related factors,” the researchers wrote.

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Glintborg B, Loft AG, Omerovic E, et al. To switch or not to switch: results of a nationwide guideline of mandatory switching from originator to biosimilar etanercept. One-year treatment outcomes in 2061 patients with inflammatory arthritis from the DANBIO registry [published online November 5, 2018]. Ann Rheum Dis. doi:10.1136/annrheumdis-2018-213474