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    A noteworthy margin of error in psoriasis?

    Similarity margin for biosimilars may be 'unacceptably wide.'


    “One physician might consider these parameters sufficient and comfortably prescribe the biosimilar as a replacement for the originator; however, another clinician might require more conservative margins.”

    — Marilyn T. Wan, MBChB, MPH, University of Pennsylvania Perelman School of Medicine

    Dr. Wan and colleagues reported specific data for the four double-blind, randomized, controlled trials that compared biosimilars to reference agents.

    In a trial of 350 patients randomized 1:1 to the biosimilar adalimumab-atto or adalimumab, the margin of error was ±15% and the study power was 0.90, authors said. The primary outcome was mean percent improvement in PASI from baseline to Week 16. The reported response rate in the trial was 86.6% for the biosimilar vs 88% for the reference drug.

    Another trial looked at the biosimilar etanercept-szzs versus etanercept that included 531 patients, the margin of error was ±18% and the study power was 0.90. For the primary outcome of PASI 75 at Week 12, the response rate was 70.4% for the biosimilar and 71.6% for the originator drug.

    The margin of error was also ±18% in a randomized study of CHS-0214 vs etanercept including 521 patients, but the study power was yet to be determined, authors of the meta-analysis said at the time of their report. The primary outcome was PASI 75 and the response rate was 64.5% and 62.3%, respectively, for CHS-0214 and etanercept.

    The final randomized comparative trial, which had a margin of error of ±14% and a study power of 0.80, compared BCD-057 to adalimumab in 344 patients.5 The primary outcome is PASI 75 at 16 weeks and the response rate has not yet been determined, according to the meta-analysis report.



    • Dermatologists need to be aware of margin of error and related issues that can affect the results of biosimilar clinical trials.
    • Sample size, study population variability, study site geography, and clinical expertise can impact the results of biosimilar trials.
    • Margin of error, or similarity margin, is the maximum allowable difference between biosimilar and a reference agent on a particular treatment measure.
    • The similarity margins used in recent psoriasis trials may be unacceptably imprecise for some prescribing clinicians.  




    The study’s authors reported research funding and other disclosures related to commercial entities including AbbVie, Inc, Amgen, Boehringer Ingelheim, Dermira, Eli Lilly and Company, Janssen Pharmaceutical, Novartis, Regeneron, and Sun Pharmaceutical Industries Ltd, among others. Full disclosures are listed in the Journal.


    • Wan MT, Strober BE, Wu JJ, et al. “How similar are the treatment responses to biosimilars in patients with psoriasis? A systematic review of statistical margins in comparative clinical trials,” JAAD. DOI:10.1016/j.jaad.2017.05.032.
    • “Study to Compare Effi cacy and Safety of ABP 501 and Adalimumab (HUMIRA®) in Adults With Moderate to Severe Plaque Psoriasis,” ClinicalTrials.gov.
    • “Study to Demonstrate Equivalent Effi cacy and to Compare Safety of Biosimilar Etanercept (GP2015) and Enbrel (EGALITY),” ClinicalTrials.gov
    • “Comparison of CHS-0214 to Enbrel (Etanercept) in Patients With Chronic Plaque Psoriasis (PsO),” ClinicalTrials.gov.
    • "Comparative Clinical Trial of Effi cacy and Safety of BCD-057 and Humira® in Patients With Moderate to Severe Plaque Psoriasis (CALYPSO),” ClinicalTrials.gov



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