Author Tanya Bentley and co-authors identified key challenges in modelling biosimilars based on a targeted literature search and review. Their research found that the impact of introducing biosimilars to the US market is unpredictable due to uncertainties surrounding pricing, regulatory actions and market penetration. Developing budget impact and cost-effectiveness models for these products will aid decision-makers, but will pose unique challenges.

Their results will be presented at the 37th Annual Meeting of the Society for Medical Decision Making, which will take place in St Louis, MO, USA on 18–21 October 2015.

Pricing
Uncertainties about future biosimilar pricing make it very difficult to develop models to predict this variable. Price estimates could be based on product- and setting-specific predictive modelling. Alternatively, models could assume an average 35% biosimilar discount at 10 years post-market entry. However, recent discounts of 45% for biosimilar infliximab in France [2] and of 72% in Norway [3] may make these predictions inaccurate.
 
FDA decisions
Models will depend on US Food and Drug Administration (FDA) decisions regarding biosimilar interchangeability and extrapolation of indications. If a biosimilar is not deemed interchangeable, then a reduced market share has to be assumed. Other variables affecting the market share are the administrative costs of pharmacist substitution requests, e.g. prior authorization and prescriber notification, and pharmacovigilance requirements and difficulties. If biosimilar indications differ from those of the reference biological, modelling off-label biosimilar use may not be appropriate.

Market share
With biosimilar market penetration uncertain, market share estimates should include the impact of price, interchangeability and indications. In the absence of available data, the authors state that an average 60% biosimilar penetration achieved 10 years post-market entry could be assumed. Although this is perhaps a bit optimistic. Looking at the EU, where biosimilars have been on the market since 2006, market shares vary widely between different countries and the overall market share for biosimilars overall remains low [4]. The authors do say, however, that explicit sensitivity analyses with wide confidence intervals for price and market share should be conducted in all biosimilar models.

The authors conclude that ‘while uncertainties exist in developing budget impact and cost[-]effectiveness models for any new product, the interacting components involved in biosimilars make mode[l]ling particularly challenging’.

Conflict of interest
The authors of the abstract [1] did not provide any conflict of interest statement.

Editor’s comment
It should be noted that this study is to be published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal. 

Related articles
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Relative effectiveness and cost minimisation for biosimilars
 
References
1. Bentley TGK, Anene A, Broder MS. Pharmacoeconomic modelling of biosimilars in the US: a conceptual framework. Poster PS3-9. 37th Annual Meeting of the Society for Medical Decision Making; 18-21 October 2015; St Louis, MO, USA.
2. GaBI Online - Generics and Biosimilars Initiative. Biosimilar infliximab offered to French hospitals at 45% discount [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 Sep 18]. Available from: www.gabionline.net/Biosimilars/News/Biosimilar-infliximab-offered-to-French-hospitals-at-45-discount
3. GaBI Online - Generics and Biosimilars Initiative. Huge discount on biosimilar infliximab in Norway [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 Sep 18]. Available from: www.gabionline.net/Biosimilars/General/Huge-discount-on-biosimilar-infliximab-in-Norway
4. GaBI Online - Generics and Biosimilars Initiative. Use of biosimilars in Europe [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 Sep 18]. Available from: www.gabionline.net/Reports/Use-of-biosimilars-in-Europe

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