6 Biosimilar Questions Answered

Steven R. Feldman, MD, PhD


June 04, 2015

Editor's Note: In the April issue of Seminars in Arthritis and Rheumatism, Steven R. Feldman, MD, PhD, professor in the Department of Dermatology at Wake Forest Baptist Medical Center in Winston-Salem, North Carolina, authored an essay[1] urging rheumatologists and clinicians treating inflammatory disorders to understand the issues related to incorporating biosimilar medications into clinical care. Medscape asked Dr Feldman a few short questions about what these agents are and how they should be used.

Medscape: What are biosimilar drugs?

Dr Feldman: Biosimilars are large, complex drugs designed and proven to be very similar to existing biologic drug products.

Medscape: In what conditions are biosimilars being used or studied?

Dr Feldman: Biosimilars are being used and studied in conditions where there are already biologic drugs being used. This includes the treatment of cancer and inflammatory diseases.

Medscape: How many biosimilars are available?

Dr Feldman: In March, the US Food and Drug Administration approved Zarxio™ (filgrastim-sndz), the first biosimilar given the green light in the United States. Its reference product is Neupogen® (filgrastim), and the new compound is approved for the same indications, including to treat neutropenia in patients receiving chemotherapy. A few other biosimilars have been approved in Europe and in other countries for treating rheumatologic conditions.

Medscape: What is the approval process?

Dr Feldman: The approval process is being defined. Basically, a biosimilar has to undergo extensive laboratory testing to assure that it will have—as best we can tell—similar biological activity as the original biologic drug product. Then, the biosimilar will also require testing in humans to show that it stays in the body for a similar amount of time and probably that it has similar effects in humans.

Medscape: What are the advantages and disadvantages of these agents compared with reference drugs?

Dr Feldman: The biggest advantage is that they may lower the cost of treatment. Reference biologics have revolutionized medicine, providing very safe and very effective treatments for some horrible diseases. But they can cost tens of thousands of dollars per year. Hopefully, biosimilars will result in a price war and bring costs down substantially (at least we hope so).

Medscape: Are they completely interchangeable with reference compounds, and in what type of patient might they be appropriate?

Dr Feldman: That remains to be seen. Biologics are so complicated that they cannot be perfectly replicated. So there is concern that biosimilars may have somewhat different biologic activity from the reference product. But I think it helps to remember that biologics are so complicated that even the company that makes the reference product cannot perfectly replicate the drug every time. So we are already happily living with some degree of uncertainty. Biosimilars will provide far, far more data on biosimilarity than we currently have for the variation in the current reference products. So the residual uncertainty with biosimilars doesn't bother me.

Medscape: On the basis of your recent essay in Seminars in Arthritis and Rheumatism, what advice do you have for practicing clinicians on incorporating biosimilars into practice?

Dr Feldman: My advice is that if they are good enough for the regulators, they are good enough for me and my patients. The reference biologics we have now have been life changing drugs for many patients, despite having some batch-to-batch variation. Just because there are some slight differences and uncertainty, it should not scare us from using the reference products or the biosimilars in our patients who need them.


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