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What Are Biosimilars? Top Facts You May Not Know

Medically reviewed on Nov 09, 2016 by L. Anderson, PharmD

What Is A Biosimilar?

A biosimilar is a biological product that is very similar to a reference biologic and for which there are no clinically meaningful differences in terms of safety, purity, and potency. An example of an approved biosimilar is Amjevita (adalimumab-atto), the first biosimilar approved for the blockbuster Humira (adalimumab) used to treat rheumatoid arthritis and psoriasis, among many other uses.

However, a biosimilar is not considered a “generic” in the same way that a traditional drug is determined to be a generic. As with generics, biosimilar cost savings for healthcare systems and the consumer are expected to be significant. According to the RAND Corporation, biosimilars could save the U.S. health system close to $44 billion in the next ten years.

What is a Biologic?

If a biosimilar is a biologic, then what is a biologic? Biological products can include a wide range of products including vaccines, blood components, gene therapy, tissues, and proteins, like monoclonal antibodies and cell signaling proteins. Unlike most chemically-derived small-molecule drugs, biological products are generally derived from a living organism, such as humans, animals, microorganisms or yeast. Biologics are used to treat patients with cancer, kidney diseases and autoimmune diseases, such as rheumatoid arthritis and Crohn's disease.

For example, Enbrel (etanercept) or Humira (adalimumab) are referred to as “large-molecule” drugs because they are larger and more complex in structure than small-molecule drugs. These products are very expensive, often in the tens-of-thousands of dollars per year, due to costs linked to complicated development and manufacturing. Often, patients will need to access these medications through a specialty pharmacy.

Are Biosimilars Exactly The Same As The Biologic?

Biosimilars are just that; similar because they do not have to be exact copies of the active ingredient, as with small-molecule drug generics. In 2010, the President signed into law an abbreviated approval pathway for biologics to encourage production, create competition, increase treatment options and reduce healthcare costs. Under the new law, a biological product may be demonstrated to be “biosimilar” if data show that the product is “highly similar” to an already-approved biological product.

The new law, known as the Biologics Price Competition and Innovation Act of 2009 (BPCI Act), aligns with the FDA’s longstanding policy of permitting appropriate reliance on drug science that has already been established, thereby saving time, resources and unnecessary duplication of animal testing or human clinical trials. How the BPCI Act will fare through an ACA repeal under the Trump administration has yet to be seen.

Zarxio: A Biosimilar to Neupogen

In March, 2015 the FDA approved the first U.S. biosimilar -- Sandoz’s Zarxio (filgrastim-sndz), the biosimilar for filgrastim (Amgen's Neupogen). Zarxio is a recombinant granulocyte colony-stimulating factor used to boost white blood cells after cancer treatments that deplete these necessary infection-fighting cells. Zarxio is highly similar to the brand biologic and has no clinically meaningful differences with Neupogen in terms of safety, purity, and potency. The FDA stated that “robust” pharmacokinetic and pharmacodynamic comparative studies supported biosimilarity with the original filgrastim.

Inflectra: A Biosimilar to Remicade

After Zarxio, Inflectra (infliximab-dyyb) by Celltrion was the second biosimilar approved in the U.S. Inflectra, a tumor necrosis factor (TNF) blocker, is biosimilar to Janssen’s Remicade (infliximab) originally approved in 1998.

Inflectra can be prescribed for the same indications as Remicade, including rheumatoid arthritis, Crohn’s disease, ankylosing spondylitis (spine arthritis), ulcerative colitis, psoriatic arthritis, and plaque psoriasis.

Erelzi: A Biosimilar to Enbrel

In August 2016 the third biosimilar, Sandoz's Erelzi (etanercept-szzs), was FDA-approved. Erelzi is biosimilar to Amgen’s tumor necrosis factor (TNF) blocker Enbrel. Erelzi is the first approved biosimilar for etanercept, and is used for the same five indications for Enbrel: rheumatoid arthritis, polyarticular juvenile idiopathic arthritis, psoriatic arthritis, ankylosing spondylitis, and plaque psoriasis.

It’s important to note that Erelzi has been approved as a biosimilar, not as an interchangeable product. Physicians must write the prescription specifically for Erelzi, as pharmacists cannot automatically substitute Erelzi for Enbrel.

Amjevita: A Biosimilar for Humira

Amgen’s Amjevita (adalimumab-atto) is the first U.S. biosimilar approved for adalimumab (Humira) in September 2016. It is used for the treatment of seven inflammatory diseases, including rheumatoid arthritis, Crohn's disease, and plaque psoriasis. Amjevita is an anti-TNF-α monoclonal antibody that has the same amino acid sequence as adalimumab.

The pharmacist needs direction from the prescribing doctor to substitute Amjevita for Humira, as it is not approved as an interchangeable product. Common side effects include increased risk of infections and injection site reactions. Amjevita is available in a pre-filled syringe or auto-injector.

How Are Biosimilars Named?

Naming of biosimilars is still a moving target. It is felt that biosimilars and the corresponding biologics need different names to prevent confusion, but opinions differ on the specifics. To date, all biosimilars have been approved with unique brand names, but differing nonproprietary names.

FDA issued a draft guidance and proposed rule in August 2015. Currently, FDA has designated a naming convention for approved biosimilar nonproprietary names that incorporates four lowercase letters (a suffix). FDA has stated drug companies can propose up to 10 suffixes for each new biosimilar.

Currently, the newly licensed biosimilars (none of which are deemed interchangeable by the FDA) have gained the unique 4-letter suffix. Some are linked with the manufacturer (filgrastim-'sndz' for Sandoz), and some apparently random (infliximab-dyyb). How this will change with naming of interchangeable biosimilars awaits to be seen.

Can Pharmacists Automatically Substitute a Biosimilar for a Brand?

It depends. In general, biosimilars cannot be dispensed in place of another biological product unless a physician or other healthcare professional specifically prescribes the biosimilar product by name.

However, according to the FDA, automatic substitution can happen if the products are deemed interchangeable. If the product has been determined to be interchangeable, then it is biosimilar to the reference product AND will produce the same clinical result as the reference product in any given patient. Interchangeable also means the original biologic and the new biosimilar can be switched back and forth in patients without a risk of diminished safety or efficacy.

Pharmacists will be responsible for knowing which biological products are interchangeable, and can check The Purple Book to find these products.

The Purple Book

The Purple Book will be the go-to resource for pharmacists and other health care providers interested in making an interchange between a reference biologic and a biosimilar. Similar to The Orange Book used to compare generic products to their brand name counterparts, The Purple Book has been developed by the FDA to list each reference biological product and the corresponding biosimilar and interchangeable biological product.

Those biosimilars designated as interchangeable will have no clinically important differences from the original product. Variation in formulation, delivery device, indications, and routes of administration may be acceptable.

The Cost of Biosimilars

The size of the molecule is not the only thing large about biologics. Seven of the top 10 drugs by sales in the U.S. in 2014 were biologics. In fact, AbbVie’s Humira sales in 2015 tipped at just over $14 billion, the number one seller. And as reported in The Economist, biologics could encompass over 30 percent of total big pharma sales by 2023.

How payers - and patients - will handle the burgeoning cost of biologics and biosimilars is a question that must be answered. Insurance groups are pushing back on the price tags, and for patients who lack adequate insurance, potentially life-saving biologic therapy can be completely out of reach.

As reported by SeekingAlfa, Hospira has noted biosimilars in the U.S. will most likely will be sold at discounts of 10 to 40 percent from the branded competitors.

Are There Concerns With Biosimilars?

Biosimilars have been available in Europe for years, and there have been some product-related and clinical issues raised with biosimilars. For example:

  • Will use of biosimilars for unapproved or “off-label” indications based on extrapolated data raise safety issues?
  • Should post-marketing, phase IV safety studies be initiated to actively monitor for previously unreported side effects?
  • Will clinicians be concerned that biosimilars are not identical to the innovator product, limiting prescribing?
  • Could new types of immunogenicity be seen with biosimilars due to newly introduced substances during the manufacturing process?
  • Will naming conventions lead to biases in prescribing or not?

Which Biosimilars May Be Up for Approval Next?

In the U.S., at least six more biosimilar products may be available for FDA review in the next decade due to patent loss. Examples include:

While the biologics Neupogen (filgrastim) and Granix (tbo-filgrastim) are both filgrastim products, they each went through the full BCPI Act approval process and therefore are not considered “biosimilar”. Companies such as Teva, Hospira and Sandoz are now rapidly working in this area and developing biosimilar products.

The Case of Granix (tbo-filgrastim)

There's always an exception, and this is no different with biosimilars. Teva's Granix (tbo-filgrastim) is not technically considered a biosimilar to Neupogen (filgrastim) because it was filed with a full BLA and clinical trials to determine effectiveness before the the publication of FDA’s new biosimilar pathway. FDA approved Granix to treat neutropenia, low white blood cells caused by receiving cancer treatment with chemotherapy. Even though Granix and Neupogen slightly in structure, their effectiveness and safety are not significant. Tbo-filgrastim's effectiveness was evaluated in a clinical study of 348 adult patients with advanced breast cancer receiving treatment with the anti-cancer drugs doxorubicin and docetaxel.

Granix's "tbo" suffix is used to distinguish it's nonproprietary name from the reference biological product Neupogen (filgrastim).

Finished: What Are Biosimilars? Top Facts You May Not Know

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