What Is a Biosimilar Medicine?
Updated on November 19, 2025
The U.S. Food and Drug Administration (FDA) has approved multiple biosimilars for breast cancer treatments, as well as treatments for side effects. These include six Herceptin biosimilars, six Neulasta biosimilars, six Xgeva biosimilars, and four Neupogen biosimilars.
Many experts believe that biosimilars, which tend to be less expensive than the original medicine, may allow more people to have access to treatments for cancer and other diseases. But what is a biosimilar medicine, and how do researchers determine if they are as safe and effective as the original drug?
Generics vs. biosimilars
If you’ve ever taken a store-brand (generic) acetaminophen in place of Tylenol for a headache, you know that it works about the same as the brand-name medicine. That’s because the active chemical ingredients of the generic and brand-name are identical. Additionally, the generic has gone through rigorous tests to confirm it’s as safe and effective as the brand-name medication.
Like generics, biosimilars are versions of medicines already approved by the FDA. Unlike generics, biosimilars are modeled after medicines made from natural and living ingredients (called biologic medicines) instead of chemicals. Because biologic medicines are made up of living things (for example, proteins or antibodies), they cannot be copied exactly from batch to batch.
“It’s actually impossible to create a generic protein or a generic biologic drug,” said Philip Lammers, MD, a medical oncologist who serves as medical director of clinical oncology research at Baptist Memorial Health Care. “The goal of the biosimilar drug is to be as similar as possible to the existing biologic drug in structure and in toxicity and efficacy.”
What are the advantages of biosimilars?
Because biologic medicines are expensive to make, many of them can cost thousands of dollars per month. The high cost may prevent some people from receiving the treatment.
One advantage of biosimilars is that the medicines tend to be less expensive than biologic medicines. The competition from lower-cost biosimilars can help lower the costs of the biologics, too. For example, a 2023 study on Herceptin biosimilar medicines found that the price of Herceptin, along with its biosimilars, dropped from 2019 — when the first Herceptin biosimilar came to market — to 2022. With more biosimilars, researchers also hope more people can gain access to these medicines.
Listen to the episode of The Breastcancer.org Podcast featuring Dr. Lammers discussing biosimilars.
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Biosimilars: What Are They and What Are Their Advantages?
Mar 30, 2017Are biosimilars safe and effective?
Before biosimilars are approved by the FDA, multiple studies must show that the medicines are as safe and effective as the original biologics. The biosimilars and biologics must also
be made from the same types of sources (for example, same living ingredients).
provide the same benefits when treating diseases or medical conditions.
be given at the same strength and dosage.
have no differences in side effects.
Once a biosimilar is approved by the FDA, it also undergoes what’s called “pharmacovigilance.” This means that the manufacturer continues to monitor the safety and efficacy of the biosimilar to make sure the biosimilar doesn’t cause any new side effects and continues to be effective.