Biosimilars in the United States: Current Status and Future Implications
Biosimilars in the United States: Current Status and Future Implications
December 04, 2018
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Outcomes after switching to Enbrel biosimilar influenced by patient-related factors

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Adjusted treatment retention rates after 1 year were lower among patients who switched from etanercept to a biosimilar compared with the historic originator cohort, but nonetheless higher than those who did not switch, according to data published in the Annals of the Rheumatic Diseases.

In addition, treatment withdrawal was more common among patients who were not in remission, the researchers wrote.

“Real-world evidence on effectiveness of switching to biosimilar etanercept is scarce. In Denmark, a nationwide guideline of mandatory switch from 50 mg originator to biosimilar (SB4) etanercept was issued for patients with rheumatoid arthritis, psoriatic arthritis and axial spondyloarthritis in 2016,” Bente Glintborg, MD, PhD, of Gentofte and Herlev University Hospital, and colleagues wrote.

 
Adjusted treatment retention rates after 1 year were lower among patients who switched from etanercept to a biosimilar compared with the historic originator cohort, but nonetheless higher than those who did not switch, according to data.
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They added, “Based on data from the nationwide DANBIO registry, we have previously reported outcomes after a similar nonmedical switch from the originator to biosimilar infliximab. Switch outcomes for the two biosimilars might differ due to different active substances (monoclonal antibodies vs. receptor fusion protein) and increasing experience with, and confidence in, the use of biosimilars in patients and community over time.”

To evaluate the clinical characteristics, retention rates and treatment outcomes among patients treated with etanercept (Enbrel, Amgen) who either switched to SB4 (Benepali, Biogen) or maintained their regimen, Glintborg and colleagues conducted an observational cohort study using data from the DANBIO registry. According to the researchers, the registry covers more than 95% of all adults with rheumatic diseases treated in Denmark with biologic disease-modifying antirheumatic drugs. The researchers included in their study 2,061 patients with RA, PsA and axial spondyloarthritis, who were treated with etanercept by April 1.

Patients were grouped into one of three cohorts: Switchers, who switched from the originator drug to SB4 between April 1, 2016, and Jan. 1, 2017; non-switchers, who remained with etanercept during follow-up; and back-switchers, who switched to SB4 but later discontinued and returned to etanercept during follow-up. In addition, the researchers identified a historic comparison cohort of 2,363 patients treated with etanercept by Jan. 1, 2015. Glintborg and colleagues analyzed crude and adjusted treatment retention using Kaplan-Meier plots and Cox regression.

According to the researchers, 79% of the 2,061 patients treated with etanercept switched to SB4. Among those who switched, disease activity and flare rates remained unchanged from 3 months pre-switch to 3 months post-switch. Patients who did not switch were often treated with 25 mg of the originator drug. Adjusted retention rates over 1 year were 77% for non-switchers (95% CI, 72-82), 83% for switchers (95% CI, 79-87) and 90% among the historic cohort (95% CI, 88-92).

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In addition, patients not in remission had lower retention rates than patients who achieved remission. This remained true among both switchers (crude HR = 1.7; 95% CI, 1.3-2.2) and non-switchers (crude HR = 2.4; 95% CI, 1.7-3.6). During follow-up, 7% of switchers went back to etanercept. These patients’ clinical characteristics were similar to those of switchers, and their reasons for SB4 withdrawal were mainly subjective, the researchers wrote.

“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,” Glintborg and colleagues 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.” – by Jason Laday

Disclosure: Glintborg reports professional relationships with AbbVie, Biogen, Pfizer and MSD. Please see the study for all other authors’ relevant financial disclosures.