Understanding the “interchangeable” biosimilar designation

Interchangeable biosimilars in the news again


This recent interchangeable designation, which applies to all approved indications of Abrilada, is based on data from the additional Phase 3 REFLECTIONS B538-12 study which demonstrated the safety and efficacy of switching patients between the two products multiple times. 

In the case of Abrilada, it is the second biosimilar designated interchangeable with Humira, the other being Cyltezo (adalimumab-adbm) from Boehringer Ingelheim and the fifth biosimilar overall to be deemed interchangeable.

What exactly is an “interchangeable” biosimilar?

Global situation


The United States is unique in instituting a separate legal definition of an interchangeable biosimilar.  Other countries have different attitudes. In the European Union (EU) for example, where biosimilars were introduced much earlier than in the US, the decision of allowing substitution at the pharmacy level lies with each member state and the biosimilar regulations do not legislate for it.

The European Medicines Agency (EMA) and the Heads of Medicines Agencies (HMA) issued a joint statement in April 2023 (2) confirming that biosimilar medicines approved in the EU are interchangeable with their reference medicine or with an equivalent biosimilar.

In other countries, such as Japan, interchangeability is automatically applied when the biosimilar is approved.

Global Biosimilar regulations continue to evolve

Since the development of the original biosimilar regulatory pathways in the mid 2000s, many products have been examined and scores approved, re-enforcing the credibility of the scientific basis behind the concept of “biosimilarity”.

The regulatory landscape continues to develop and evolve, building on nearly twenty years of experience allowing guidelines to be refined and updated as necessary.  However, the essential premise of demonstrating biosimilarity, prior to safety, efficacy and immunogenicity assessment, through initial extensive structural and biological characterization and comparability against the reference product remains true.  

The analytical tools we now have to assist us in these tasks are multiple and any good biosimilarity study will require the judicious choice of orthogonal techniques to interrogate the molecular structure of the complex biologic.


Where can I find out more?

An overview of global Biosimilar regulations and the pros and cons of various methods which can be used to examine both novel and biosimilar primary and higher order structure will be outlined in an upcoming Masterclass.