Interchangeability for Biosimilars: The Next Big Step

Biosimilars have now reached the next and some will say the pivotal plateau: determining interchangeability.

Interchangeability is important because it means a biosimilar can be substituted for a biologic by a pharmacist without the approval of a physician.

“Interchangeable” is a very interesting word because it has no synonym. There’s no other way to say what it means. Determining interchangeability for biosimilars is essential in order for them to realize the cost savings for which patients have been waiting.

To understand why interchangeability is important, it’s necessary to understand the difference between generic and biosimilar drugs.

A generic is an exact copy of a small molecule, chemically-derived drug. It’s exact because it has the same ingredients. Interchangeability for a generic drug is a given: you just follow the recipe.

A biologic is complex, large molecule which is made in living cells by adding a piece of DNA to a cell.You can grow a copy, but it will never be exactly the same. That is why copies of biologics are called biosimilars: they are approved by the FDA, not as exact copies, but as highly similar versions of the original biologic.

The Biologic Price Competition and Innovation Act (BPCIA), which is part of the Affordable Care Act, created an abbreviated pathway for the FDA to approve biosimilars of a biologic just as the Hatch-Waxman Act created such a pathway for generic drugs. But interchangeability can’t be assumed for biosimilars because it and the original biologic aren’t identical.

The BPCIA allows the FDA, on extra submissions from the biosimilar applicant, to give the biosimilar the additional designation as interchangeable for the original biologic. The FDA has, to date, approved four biosimilars. None has yet been designated as interchangeable.

On Jan. 17, the FDA issued its long-awaited draft guidance for applicants on the recommended submission criteria for an interchangeable biosimilar. I wrote two articles on the draft guidance: the first published the day the draft guidance came out, with immediate reaction from attorneys, and the second a week later with more reactions.

Some commenters were concerned that the draft guidance wasn’t clear enough while others felt it was a good first step that would become better through comments from stakeholders.

Comments on the draft guidance are to be submitted to the FDA by March 20, and Bloomberg BNA will cover what stakeholders in the development of biosimilars have to say about it.

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