Tildrakizumab-asmn: What’s in a Name?

The US FDA approved tildrakizumab-asmn on 21 March 2018 [1], adding to the armamentarium of interleukin (IL)-23-inhibitor biologic therapies available for the treatment of plaque psoriasis. Results of the pivotal reSURFACE 1 and reSURFACE 2 phase III trials have already been published and available for over 8 months [2], but one thing may have caught the eye of people closely following this drug: the four-letter suffix “asmn”.

Tildrakizumab-asmn is the first originator biologic in the dermatology space to adopt the 2017 FDA-recommended nonproprietary naming convention for biological products, although biosimilars in dermatology have been using this nomenclature since 2016. Under this convention, originator biologics and biosimilar drugs will be named by “a combination of the core name and a distinguishing suffix that is devoid of meaning and composed of four lowercase letters” [3]. The suffix is not intended as an acronym or to convey any specific information. A biosimilar will be given the same nonproprietary core name as the originator biologic but a different four-letter suffix. Pharmaceutical companies may propose up to ten possible suffixes for their product, conforming to certain rules to prevent confusion [3], with the FDA making the final choice.

The use of the four-letter suffix has several purposes. It will help patients receive the correct product as intended by their prescriber. It will assist with pharmacovigilance efforts to accurately track the ordering, prescribing, and dispensing of biosimilar products. Finally, it will help maintain accurate perceptions of bio-originator and biosimilar products.

Adoption of this nomenclature by this newly approved drug demonstrates an anticipated increased role of biosimilars in dermatology. Six biosimilars in dermatology are currently FDA approved: infliximab-dyyb, infliximab-abda, infliximab-qbtx, etanercept-szzs, adalimumab-atto, and adalimumab-abdm, and more are on the horizon. Additionally, the FDA has recommended all already approved originator biologics to retrospectively receive a unique four-letter suffix [3]. Dermatologists should be aware of the naming conventions of biologic and biosimilar medications as they become increasingly prominent in the field of dermatology.


  1. 1.

    Sun Pharma Announces U.S. FDA Approval of ILUMYA™ (tildrakizumab-asmn) for the Treatment of Moderate-to-Severe Plaque Psoriasis. 2018. https://www.prnewswire.com/news-releases/sun-pharma-announces-us-fda-approval-of-ilumya-tildrakizumab-asmn-for-the-treatment-of-moderate-to-severe-plaque-psoriasis-300617454.html.

  2. 2.

    Reich K, Papp KA, Blauvelt A, Tyring SK, Sinclair R, Thaci D, et al. Tildrakizumab versus placebo or etanercept for chronic plaque psoriasis (reSURFACE 1 and reSURFACE 2): results from two randomised controlled, phase 3 trials. Lancet. 2017;390(10091):276–88.

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    Nonproprietary Naming of Biological Products—Guidance for Industry. 2017. https://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM459987.pdf.

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Correspondence to Eric J. Yang.

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Eric J. Yang, Kristen M. Beck, and Wilson Liao have no conflicts of interest.

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Yang, E.J., Beck, K.M. & Liao, W. Tildrakizumab-asmn: What’s in a Name?. Am J Clin Dermatol 19, 291–292 (2018). https://doi.org/10.1007/s40257-018-0357-6

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