What Are Biosimilars?

First Biosimilar for Rheumatoid Arthritis FDA-Approved in 2016

Nurse administering an I.V.
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You likely heard the term "biosimilars" for the first time a few years ago. As drugmakers focused on the development of biosimilars and the FDA (U.S. Food and Drug Administration) determined how biosimilars would be reviewed and licensed, we waited to see which biosimilar would become the first to be approved for rheumatoid arthritis.

Inflectra (infliximab-dyyb), the biosimilar to Remicade, was approved by the FDA in April 2016 for rheumatoid arthritis and certain other inflammatory conditions, making it the first for those conditions.

And, there are others on its heels. Amgen is developing a biosimilar to Humira (adalimumab) and submitted a Biologics License Application for the biosimilar in November 2015. Boehringer Ingelheim Pharmaceuticals is developing a biosimilar to Rituxan (rituximab). Coherus Biosciences has an Enbrel biosimilar in development.

What Are Biosimilars?

By definition, a biosimilar is a biological product that is "highly similar" to a U.S.-licensed biological product, without regard to minor differences in clinically inactive components. There must also be no clinically significant difference in terms of safety, purity, and potency between the biosimilar and the original, already-approved biological product, known as the reference drug.

What Constitutes a Biological Product?

Biological products are products that are made using human or animal materials. According to the FDA, biological products can include vaccines, blood, blood components, allergenics, somatic cells, gene therapy, tissues, and proteins.

Biological products differ from small-molecule prescription drugs which are synthesized using chemical processes. Biological products are more complex and are either derived from natural sources or produced using biotechnology.

The first biologic drug for the treatment of rheumatoid arthritis was approved by the FDA in 1998.

That drug was Enbrel (etanercept), which was classified as a TNF (tumor necrosis factor) blocker. Tumor necrosis factor is a cytokine which is involved in the inflammatory process. More than a dozen years later, we can say with confidence that the approval of Enbrel dramatically changed how rheumatoid arthritis and other inflammatory types of arthritis are treated today. Since Enbrel, several more TNF blockers have been approved and marketed as well as biologics that target B-cells, T-cells, and IL-6.

The Process of Licensing Biosimilars

Most biological products are licensed under the Public Health Service Act, unlike small-molecule prescription drugs, which fall under the Food, Drug and Cosmetic Act. The Patient Protection and Affordable Care Act of 2010 amended the Public Health Service Act in order to shorten the path for licensing biosimilars.

There were kinks in the regulatory process for biosimilars due to concern about the safety, effectiveness, and equivalency of biosimilars.  Even with Inflectra now approved, questions remain. Can patients be assured that a biosimilar drug will be of equal quality and effectiveness as its reference drug? Can doctors prescribe the biosimilar and reference drugs interchangeably? Will insurance force patients to use biosimilars because of lower cost?

Are Biosimilars Like Generics?

Biosimilars and generics are not synonymous. "Generic" refers to small-molecule drugs that are deemed bioequivalent to an already existing small-molecule drug, as dictated by the Food, Drug and Cosmetic Act. According to the FDA, if a product is deemed to be "biosimilar," the product will be interchangeable with the already-approved biological product and expected to produce the same clinical result.


Information for Consumers (Biosimilars). U.S. Food and Drug Administration. Updated 08/27/15.

Information on Biosimilars. U.S. FDA. Updated 02/22/16.

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