Effectiveness of Etanercept Biosimilar vs Originator in Psoriatic Arthritis

In patients with psoriatic arthritis (PsA), real-world data support the feasibility of switching from reference etanercept to the etanercept biosimilar SB4, as the biosimilar is effective in maintaining a state of low disease activity in the majority of patients evaluated. Findings from this study were published in the Journal of Dermatological Treatment.

In this 1-year, open-label, prospective study conducted in Rome, Italy, investigators sought to verify the ability of SB4 to maintain low disease activity in patients who switched to the biosimilar after 1 year of treatment with the etanercept originator. The primary end point of the study was the proportion of patients who were previously treated with reference etanercept and who maintained a clinical Disease Activity Index for Psoriatic Arthritis (cDAPSA) score ≤13 after 1 year of switching to SB4.

A total of 87 patients with PsA and low disease activity at baseline (ie, cDAPSA ≤13) were switched, on a nonmandatory basis, from reference etanercept to SB4, and followed prospectively for 1 year. Recognizing that cDAPSA does not include certain key measures of disease activity in patients with PsA, including enthesitis and severity of skin involvement, the researchers used minimal disease activity (MDA) as an additional criterion for classifying the patient cohort in a state of low disease activity. Of note, at baseline, 93% (81 of 87) of the participants had low disease activity per MDA criteria.

Because both cDAPSA ≤13 and MDA 5/7 exclude the effect of PsA on patients’ quality of life and severity of itching, those 2 clinical domains were measured via the Dermatology Life Quality Index questionnaire (range, 0-30) and the Visual Analogue Scale for itching (graded from 0 to 100). Patients were considered to be in a state of low disease activity if the duration of reference etanercept administration was ≥3 months. Before switching to SB4, all patients had been receiving reference etanercept at a dosage of 50 mg once weekly. SB4 was prescribed at the same dosage and dosing intervals as the etanercept originator.

At 1 year, 17 participants lost the state of low disease activity because of an increase in ≥1 domains included in both cDAPSA ≤13 and MDA 5/7 scores. These patients were different from the 72 patients who maintained low disease activity only in that they had a higher percentage of women (60% vs 19%, respectively; P =.003).

Moreover, no significant individual index variations included in both cDAPSA and MDA scores, as well as the Dermatology Life Quality Index and Visual Analogue Scale itching, were observed from baseline to 6 and 12 months after switching from reference etanercept to SB4. At 1 year after switching from reference etanercept to SB4, 87.3% (76 of 87) of patients maintained a cDAPSA ≤13.

The investigators concluded that although the proportion of patients who failed to maintain a state of low disease activity at the end of the study was statistically significant, this loss of effectiveness was mainly a result of subjective evaluations provided by the patients, rather than by an objectifiable exacerbation of their disease.

Reference

Bonifati C, De Felice C, Lora V, Morrone A, Graceffa D. Effectiveness of etanercept biosimilar SB4 in maintaining low disease activity in patients with psoriatic arthritis switched from etanercept originator: an open label one year study [published online May 1, 2019]. J Dermatolog Treat. doi:10.1080/09546634.2019.1606886