Impacts of Biosimilar Etanercept Are Patient-specific, Not Drug-related

According to an observational cohort study, effects of switching from an originator to biosimilar etanercept depend on the patient and are not specific to the drug itself.

Patients being treated for rheumatoid arthritis, psoriatic arthritis and axial spondyloarthritis either switched from 50 mg originator (ETA) to biosimilar (SB4) etanercept (switchers) or maintained ETA (non-switchers). Non-switchers received 25 mg ETA.

Out of 2,061 ETA-treated patients, 1,621 (79%) switched to SB4. After three months, there were no differences in disease activity. After one year, both groups had similar retention rates—non-switchers, 77% (95% CI: 72% to 82%); switchers, 83% (79% to 87%); and historic cohort, 90% (88% to 92%). Patients in remission had higher retention rates compared to those not in remission, in switchers (crude HR 1.7 [1.3 to 2.2]) and non-switchers (2.4 [1.7 to 3.6]). At follow-up, 7% of switchers (n = 120) returned to ETA. According to the researchers, “Back-switchers’ clinical characteristics were similar to switchers, and reasons for SB4 withdrawal were mainly subjective.”

“We found that a nationwide switch from originator to biosimilar [etanercept] in 1,621 patients with inflammatory arthritis had no negative impact on 3 months’ disease activities, and no major safety events were observed,” the study authors wrote. “Despite mandatory switch recommendations, one in five [etanercept]-treated patients did not switch. In both patient groups, withdrawal was most common in patients not in remission. These real-world data indicate that switch outcomes in routine care are affected by non-specific drug effects and patient-related factors.”

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Sources: Healio Rheumatology, Annals of the Rheumatic Diseases