In the US, a legal framework for approving biosimilars was established in 2009, via the Biologics Price Competition and Innovation Act of 2009 (BPCI Act). As part of the US Food and Drug Administration’s (FDA) implementation of the BPCI Act, the agency published draft guidance on biosimilar interchangeability in January 2017 [2].

The draft guidance made it clear that biosimilars makers will first have to prove that their product is ‘biosimilar’ to the reference biological. Then, in order to claim ‘interchangeability’ for the biosimilar, additional information will have to be submitted to show that it ‘can be expected to produce the same clinical result as the reference product in any given patient’ and that there are no additional safety risks associated with switching [3]. In fact, to prove interchangeability, the bar seems to have been set rather high for biosimilars, with multiple switches being required.

The guidance raised many questions and opened discussion on the challenges of proving interchangeability for biosimilars. In fact, the agency extended its comment period on the guidance, after receiving requests to do so [4] and received a total of 52 comments on the draft guidance [5].

In his presentation, Dr Alvarez discusses:

• Challenges in implementing clinical trials that support interchangeability based on the current draft FDA guidance
• Adequacy/challenges of pharmacokinetic (PK) endpoints
  • Alternative study designs and statistical comparisons
• Potential alternative/additional endpoints to assess interchangeability

These subjects are covered in more detail in the following series of three articles.

Disclaimer
Dr Daniel F Alvarez, Senior Director at Pfizer, stated that the views and opinions expressed in his presentation are those of the individual presenter and should not be attributed to DIA, its directors, officers, employees, volunteers, members, chapters, councils, communities or affiliates, or any organization with which the presenter is employed or affiliated, including, without limitation, Pfizer and Hospira.

Related articles
Alternative designs for clinical switching studies

Endpoints to assess interchangeability for biosimilars

Use of PK as an endpoint for clinical switching studies

Challenges in implementing trials to prove interchangeability

References
1. Alvarez DF. Interchangeability. DIA Biosimilars Conference; 24-25 October 2017; Bethesda, Maryland, USA.
2. GaBI Online - Generics and Biosimilars Initiative. FDA issues draft guidance on biosimilar interchangeability [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2018 Apr 20]. Available from: www.gabionline.net/Guidelines/FDA-issues-draft-guidance-on-biosimilar-interchangeability
3. GaBI Online - Generics and Biosimilars Initiative. Interchangeability and switching study designs for biosimilars [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2018 Apr 20]. Available from: www.gabionline.net/Reports/Interchangeability-and-switching-study-designs-for-biosimilars
4. GaBI Online - Generics and Biosimilars Initiative. FDA extends comment period for interchangeability guidance [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2018 Apr 20]. Available from: www.gabionline.net/Guidelines/FDA-extends-comment-period-for-interchangeability-guidance
5. GaBI Online - Generics and Biosimilars Initiative. Comments on switching in FDA’s interchangeability guidance from big pharma [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2018 Apr 20]. Available from: www.gabionline.net/Guidelines/Comments-on-switching-in-FDA-s-interchangeability-guidance-from-big-pharma

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