Amgen’s Leah Christl makes the case to keep the interchangeability designation for biosimilars

Amgen and its portfolio of 11 biosimilars is standing behind interchangeability, saying the designation should not be rescinded and that the FDA needs to retain its regulatory flexibilities.

The position puts Amgen in opposition to bipartisan legislation that’s pushing to remove the interchangeability designation for biosimilars and to the industry-led Biosimilars Forum, whose executive director recently told Endpoints News they were backing the push to remove the designation. The interchangeability designation allows biosimilars to be swapped with their brand name reference products without the intervention of a prescriber.

Sandoz and other biosimilar developers have also noted the FDA “has been very clear that there are no quality differences between biosimilars that have an interchangeability designation and those that do not … we welcome any flexibility that the FDA may be applying in the requirements to achieve this interchangeability designation.”

So how far should Congress go to help biosimilar uptake?

Leah Christl

“We don’t support doing away with the interchangeability standard or making all biosimilars interchangeable by default,” Leah Christl, Amgen’s executive director for global biosimilars and the former top FDA regulator of biosimilars, told Endpoints in a phone interview this morning. She called for the FDA to retain its remit, and not diminish confidence in the market by making any major changes early on.

The FDA is in the middle of a two-day meeting where it’s debating with other regulators on what needs changing. The FDA has been flexible so far in granting interchangeability and in requiring comparative efficacy testing. Take, for example, Coherus, which was not required to run switching studies before obtaining its interchangeability designation for Cimerli (ranibizumab-eqrn), a biosimilar to Roche’s injection Lucentis, as a treatment for wet age-related macular degeneration.

In fact, of the four biosimilars that currently have an interchangeability designation, only Boehringer Ingelheim’s adalimumab biosimilar Cyltezo needed to run switching studies, Christl noted. Amgen is still seeking an interchangeability designation for its Humira biosimilar Amjevita.

“We as a company don’t think that every program needs a switching study and that’s not what we’re advocating for. We’re really focused on the FDA retaining their regulatory authorities and the flexibility they have in considering what’s scientifically appropriate for a program, instead of just removing their authority and their flexibility. We think that could be a potential risk to patients or could have a negative impact on the development of biosimilars,” she said.

Even still, Republican Sen. Mike Lee of Utah and others on both sides of the aisle have introduced a bill that would eliminate the interchangeability designation as Lee says “it is abundantly clear that switching studies are unnecessary.”

But Christl thinks these reforms are more of a misunderstanding of how the marketplace is working and how different the healthcare and payer systems are in the US and Europe:

The key thing to understand is that interchangeability in the US is relevant to pharmacy substitution, whereas interchangeability ex-US is not related to pharmacy substitution. If you look at some of the proposed bills and some of the comments in the public talk about getting rid of the additional interchangeability standards, or collapsing interchangeability into biosimilarity, such that all biosimilars would be considered interchangeable, so that would mean they’re all considered substitutable, which is not in alignment with the rest of the world.

The FDA’s meeting this week is also discussing other changes to the biosimilar approval pathway, including reevaluating the need for comparative clinical efficacy studies, which Amgen supports keeping even as the company acknowledged the studies “are not necessary for every biosimilar.”

Christl said the regulators are planning on putting out a summary after meeting next week in a three-day, closed-door session.

“Health Canada is working on revising their guidelines. EMA is going to be putting out a revised guideline, or some points to consider, for their program in terms of thinking about a tailored clinical program. So I think all regulators are engaged in this conversation on comparative efficacy testing to support biosimilars and there remain some differences on how it’s viewed across regulators,” she added.

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