Biosimilar Interchangeability Draft Guidance: How Will it Impact Specialty Pharmacy?


The interchangeability designation demonstrates that the efficacy and safety of a biosimilar is equal to the reference product.

Last month, the FDA released the long-awaited draft guidance regarding biosimilar interchangeability. The guidelines are intended to provide an overview of important scientific considerations when demonstrating interchangeability with a reference product. The FDA recommends for sponsors to conduct 1 or more switching studies to show safety and efficacy in patients alternating between the 2 products.

In a Q&A with Specialty Pharmacy Times, Jillian Godfrey Scaife, a principal at Trinity Partners, discussed the importance of the guidance and what it means for the future of specialty pharmacy.

SPT: Why is biosimilar interchangeability important?

Godfrey Scaife: A biosimilar designation means the product is highly similar to the reference product, meaning it has no clinically meaningful differences from the reference product. There are some allowable differences due to the fact that it’s a complex molecule made from a living organism. An interchangeable designation means that in addition to demonstrating biosimilarity, the product is expected to produce the same clinical results as the reference product. If a biosimilar is deemed interchangeable, the biosimilar product can be substituted for the reference product — and that part is really key. Even if a health care provider prescribes the reference product for the patient, the patient may actually receive the biosimilar version if deemed interchangeable.

SPT: Do the new guidelines for biosimilar interchangeability mean longer drug trials?

Godfrey Scaife: Not necessarily, it will really depend on the biosimilar product. When manufacturers seek approval for a biosimilar product, they submit what they call a 351(k) biologic licensed application—or BLA—that includes a number of different elements, such as an analytical study demonstrating that the biological product is highly similar to the reference product. It also includes animal studies that assess the toxicity of the product, as well as clinical studies, or study with PD data (pharmacodynamics) that demonstrates the safety, purity, and potency of the product in 1 or more of the conditions it is seeking approval in.

It is possible for the manufacturer to receive interchangeable designation upon initial approval of the biosimilar product. However, it does appear that this may be limited to biosimilar products that are used 1 time. If the biosimilar product is administered more than once, the manufacturer must also conduct a switching study to demonstrate that the safety and efficacy is the same in patients alternating between biosimilar and the reference product, as compared to patients receiving the reference product exclusively. I think it depends primarily on how the product is intended to be used: if it’s being used 1 time, an additional trial may not be needed, but if it’s being used more than once, a switching study will be required.

SPT: Will the guidelines help make physicians more comfortable in prescribing biosimilars?

Godfrey Scaife: I do think the interchangeability will make physicians comfortable prescribing the biosimilar product, because having that designation means that it had been proven that the efficacy and safety of the product is the same as the reference product, so physicians would be more comfortable in using it.

Currently, there are 4 biosimilar products that are FDA-approved, and 3 of those are within the anti-TNF class, which is for a number of autoimmune diseases. What’s interesting about this is that a lot of these autoimmune diseases are treated chronically, so patients are started on a biologic agent and stay on it as long as it’s working for them in efficacious. Many physicians are concerned right now, [because] if the patient is well-maintained and doing well on a biologic agent, there is concern that if the patients switch to a biosimilar —–if it’s not interchangeable or if it just demonstrates the biosimilarity––there might be some slight differences in how the drug metabolizes in the patient, and there could be a difference in efficacy and potentially safety. This has raised some concerns with physicians, as well as patients, who are on biologic therapies. Having the interchangeability status, I think, will help ease some of these concerns.

SPT: What should pharmacists be aware of in the future?

Godfrey Scaife: I think it will be critical for a pharmacist to be aware of the biosimilar designation—–if it’s interchangeable or if it’s just biosimilar. If the product does have an interchangeable status or designation, then the pharmacist will play a very critical role in which product the patient actually receives, because the pharmacist can substitute the biosimilar product for the reference product, even if the physician prescribes the original branded reference product. I think it would be important to educate pharmacists on biosimilars and on the designation status of biosimilar products, so they’re familiar with it and understand what the ramifications are in their day-to-day practice.

SPT: Could the guidelines effect already-approved biosimilars?

Godfrey Scaife: The one thing I found interesting was in the 4 biosimilar products that are approved to-date, all of them are administered more than once and have received a biosimilar designation; they are not interchangeable. If the manufacturers wanted to—with these biosimilars — change the designation, they will need to do an additional switching study. I think the majority of the biologic therapies that are out there today are intended to be used more than once, so this means that most companies will need to do an additional switching study if they do want to obtain that interchangeable designation.

Trinity Partners is a life science strategies consultant company that provides a number of services, including helping pharmaceutical and biotech companies both commercialize and bring their drugs to market.

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