Will Approval of an Interchangeable Biosimilar Mean that Others Are Inferior?

In terms of the biosimilar market and utilization, the US has been at least one full decade behind Europe in every respect but one. Yes, we have the EU beat in a game they avoided playing: The interchangeability gambit. The Europeans never defined interchangeability as a separate concept for biosimilars, thus leaving the individual countries to decide whether to allow unencumbered switching of biosimilars for their originator drugs.

As in other areas of biosimilar policy and regulation, the US started very slowly. Leah Christl, PhD, Associate Director for Therapeutic Biologics, OND Therapeutic Biologics and Biosimilars Team, Food and Drug Administration (FDA) stated last week at the Drug Industry Association’s annual meeting in Chicago that she expects the first interchangeable biosimilar to be approved within about 2 years. This is probably realistic, based on the timeline of the adoption of the agency’s interchangeability guidelines. Comments on the draft guidance are being read by the FDA at this time. Seven years after the passage of the legislation calling for the biosimilar approval pathway. If there were competitors in this game, we’d be desperately trying to catch up!

It seems unlikely that the FDA has any active 351(k) applications seeking the interchangeability designation, although Dr. Christl did not reveal whether this was the case. The application process is confidential; a submitted application is publicized only if the drug maker issues a press release on its ownDeck 1.png. It would seem premature to seek the interchangeability designation before the FDA’s own guidance on what the review entails is released. This may not prevent a biosimilar manufacturer that has already received approval from taking the quick step towards interchangeability, especially if they have conducted a series of switching studies that meet the FDA’s criteria (e.g., NOR-SWITCH).

Payers are chomping at the bit for an interchangeable product in the 36 states (and 3 pending) that have signed legislation allowing pharmacies to automatically substitute a biosimilar for an originator biologic.

Others have pointed out that the interchangeable biosimilar may be a boon to its manufacturer, but it may have negative effect on competitive markets. For example, a noninterchangeable infliximab may be considered by prescribers or patients somehow inferior to the interchangeable version, devaluing this biosimilar. On the other hand, the maker of “infliximab-int” could experience increased demand and boost prices (or avoid decreasing prices in the face of other noninterchangeable biosimilars coming to the market). And this may be justified. No one really knows the manufacturer’s incremental cost of achieving this designation, based on:

  • The cost of conducting additional switching studies
  • The potential cost of responding to FDA requirements for more data
  • The opportunity cost in marketing time, resulting from a delay in the application or approval

The race for a product with this extremely valuable designation drags on at a snail’s pace. I hope I’m still writing about it by the time someone reaches the finish line.


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