Biosimilars are not Generics and Other Things You Should Know

2016 was a momentous year for the biosimilar market as the first of these drugs were approved for use in the US. Of the four biosimilars introduced, it’s notable that three of them are RA medications. Inflectra, a Remicade biosimilar, was approved in April; Erelzi, an Enbrel biosimilar was approved in August; and Amjevita, a Humira biosimilar, was approved in September. The fourth biosimilar, Zarxio, is prescribed for cancer patients.

It’s important to understand that these drugs are not identical copies of the original like a manufactured generic drug is. Most medications are chemical compounds that are created through a specific process. Aspirin is a great example and the aspirin compound created in a high school chemistry class is identical in structure to the aspirin you can buy off the shelf at your local store.

Biologic drugs, however, are animal-based proteins that are grown in a lab. This applies to both the original biologic as well as the “similar” drug. While similar, just as two fingerprints are similar, the biosimilar can never be an exact match to the original. To illustrate the complexity, if aspirin (which has about 20 molecules) is a one-room log cabin, then a biologic is the Empire State Building.

To be approved by the FDA, the biosimilar must be shown highly similar to an already-approved biological product have no clinically meaningful differences in terms of safety, purity, and potency from the original (also called the “reference product”).

A second designation for a biosimilar drug is “interchangeable.” In order for a biosimilar to be designated as interchangeable with the original product, it must have several key attributes. These include having same mechanism of action, route of administration (such as infusion or injection), dosage form, and strength as the reference product. For example, if a TNF-inhibitor biologic is injected at a certain dosage once a month, the biosimilar must also be a TNF inhibitor that is injected once a month. It cannot be interchangeable, for example, if the biosimilar must be used at a higher dosage, more frequently, or via infusion instead of injection.

This is where it gets interesting.

Once a biosimilar drug has been designated as interchangeable, based on state laws, a pharmacy may substitute a biosimilar for the original biologic (like generics are often substituted for brand name medications today). Because these medications are so new, not all states have substitution laws and the ones that are in place, vary from state to state. That being said, it’s possible that a biosimilar drug might be substituted without the patient or the doctor being informed. That is, you could receive a different drug than the one you were originally prescribed.

As you might expect, there is a lot of discussion about these new drugs from all levels of healthcare — from patients all the way up to state and national regulatory bodies.

The really good news is that there are now more treatment options than ever for RA patients. Since many biologic RA drugs are also prescribed for other conditions such as ankylosing spondylitis and psoriatic arthritis, the related biosimilar drugs can also seek approval for these same conditions. Note, however, that a biosimilar cannot be approved for a condition for which the original reference drug has not also been approved.

Not only can biosimilar drugs be substituted for the original drugs (under specific laws), but doctors can prescribe them directly which (in my opinion) is a good thing. I’ve had the opportunity to participate in several forums and individual discussions with health care providers on the topic. While this is obviously up to the individual physician, the general consensus I’ve heard is that a patient who is doing well on the original drug shouldn’t be switched to a biosimilar (unless there is a medical reason to do so). However, a patient that is new to a biologic treatment might be a candidate to first try the biosimilar.

One of the things causing the most “buzz” about biosimilars is the potential reduction in cost versus the original reference product, much like a generic drug can cost less than the original. However, while biosimilars don’t have to go through the same rigorous testing steps for approval that original biologic drugs do, they still cost millions of dollars to develop and manufacture. Whether there will be cost savings for patients remains to be seen but they very likely will not be as substantial as seen with generic drugs.

While there are a lot of unknowns about biosimilars at this point (which can be scary if you’re a patient), there are many things that I like. The main thing to me is that the introduction of biosimilars are concrete evidence of research and development going on for developing RA treatments – not only in new medications which is critical, but in also expanding our current options through biosimilars. A biosimilar is a biologic drug, so the complex infrastructure to manufacture them is the same. Adding to the physical capacity to produce more biologic drugs can only be a good thing for future research and development of treatment options.

There is a lot of information available about biosimilars. A great place to start is the FDA’s website on the subject for consumers that can be found here: Information for Consumers (Biosimilars).

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.


View Comments (3)
  • Wren moderator
    2 years ago

    Excellent explanation of a complicated and confusing subject, Carla. Thank you! 🙂

  • cannonsplash
    2 years ago

    Carla – great info! I’ve wondered if a biosimilar to Enbrel will work if the original stopped working. Hopefully we can learn some of these things as people start is using biosimilar

  • Carla Kienast author
    2 years ago

    Thanks! You’re right. Since they’re similar to the original drug, there’s a lot that we can surmise, but we won’t know for sure until there is some real patient data to analyze. But it’s certainly an exciting time in research for new treatments.

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