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What is a Biosimilar?

A biosimilar is a copy version of a biologic drug. If the U.S. Food and Drug Administration approves a drug as a biosimilar, they say it is as safe and effective as the original “reference” drug that was copied.

To explain what a biosimilar drug is, we have to start with biologic drugs. A biologic drug is not made from chemicals (like how aspirin or most chemotherapy is made). A biologic drug is made by or from a living organism. It could be made by a bacteria, yeast, cell, or tissue (like how yeast makes beer). Or it may be made from cells or tissues (like blood cells or live vaccines).

To learn more about biosimilars, please watch our online quick guide on biosimilars - Coming soon

Are Biosimilars the Same as Generic Drugs?

Biosimilars are not the same as generic drugs. Because biologic drugs are so much larger and complicated to make than chemical drugs, an exact copy is almost impossible to make. Instead, a highly similar copy (biosimilar) is made.


Watch the 4-minute video explanation about biosimilars by Leah Christl, PhD, Associate Director, Therapeutic Biologics & Biosimilars at the Food and Drug Administration, or read the transcript below.

Narrator: The Cancer Support Community caught up with Leah Christl from the Food and Drug Administration, or FDA, to talk about biosimilars. These drugs are being used more and more for cancer treatment. Dr. Christl, thank you for helping us understand biosimilars and the role of the FDA in helping patients gain access to them. Tell us a bit about what the FDA does:

Leah Christl, PhD: The FDA is a public health agency, and we are responsible for promoting and protecting the public health. What that means is that we oversee the approval of drugs, biological products, medical devices.

What is a biological product?

Narrator: Biological products are drugs or vaccines that are made from organic materials, rather than from chemicals. Can you help us understand this a little better? What is a biological product and can you give us an example of one?

Leah Christl, PhD: A biological product is a product that’s typically produced in a living organism. Something like a microbe, a bacteria, a yeast, it can come from cells or from tissues. People are very familiar with going to a brewery and seeing the big fermenter, the big stainless steel container that’s there. And folks understand in terms of making beer that you’re putting different things inside that fermenter you’re adding yeast and sugar, you’re having this reaction that takes place in there and you’re making something with that organism, with that yeast, and that’s making the beer.

What is a biosimilar?

Narrator: What is a biosimilar and how does it compare to the original, “innovator” biological product or “reference product”?

Leah Christl, PhD: A biosimilar product is essentially a version of an innovator biological product. The manufacturer of the biosimilar product is trying to make a copy version of the biological product that has the same safety and effectiveness as the reference product that it’s comparing itself to, that stand-alone biological product. So, they take apart the reference product, look at it, look at the structure, look at how it works, look at it inside-out and then reverse-engineer their product essentially, to be a copy-version of that product.

So when patients receive the biosimilar versus the reference product, they can expect the same results from a safety standpoint and an effectiveness standpoint. So, if I wanted to make a beer that was just like someone else's beer, I would go and buy their beer and I would analyze it. I would try to figure out what it is that they put in it, try to figure out what their recipe is. And look at that and I try to set up my manufacturing process for my product to make what has the same characteristics as the one I am testing and the one I’m trying to copy.

FDA won't approve a biosimilar product if they don't think that it's highly similar with no clinically meaningful differences from the reference product. So, when we approve that product as a biosimilar, that means that it's met the agency standard, not only for biosimilarity, but for how the product is made, how it's manufactured, that it's going to be safe, that it's going to be well controlled, that when it moves into the marketplace it's going to be just as good as the reference product. Otherwise, FDA won't approve it, if it doesn't meet our standards.

What should patients know about biosimilars?

Narrator: What is your final thought for patients? What should patients know about biosimilars?

Leah Christl, PhD: It's FDA's position that if we approve a biosimilar product, that patients and health care providers can have confidence that that product is safe and effective for those labeled conditions of use, just like any other product that we'll approve.