Biosimilar Basics Part 2: Biosimilar Naming Conventions

Top 10 Acronyms To Know in Drug Pipeline Content

March 21, 2023
News about biosimilars is everywhere. Sometimes you just need the basics. This four-part series gets you what you need to know.

Part 1: What’s what in biosimilars? Compare and contrast.

Part 2: Top 10 acronyms in drug pipeline content.

Part 3: Getting biosimilars to market–what works and what doesn’t.

Part 4: How are biobetters different from biosimilars?

In the beginning there were brand-name drugs. And they were good, but they were expensive… something had to change. With change came new terminology (hello, biosimilars), new naming conventions and new acronyms to remember.


Starting in the mid-1980s, generic drug manufacturers could use an Abbreviated New Drug Application (ANDA) instead of the longer New Drug Application (NDA). They could do that because Congress had passed the Drug Price Competition and Patent Term Restoration Act of 1984, also known as Hatch-Waxman Amendments. This established bioequivalence as the basis for approving generic copies of brand-name drug products. The Food and Drug Administration (FDA) could now approve generic versions of brand-name drugs without asking for costly and duplicative clinical trials.1,2


Drug manufacturers couldn’t make exact copies of biologic drugs; the large molecules were too complex and variable. In 2010, as part of the Affordable Care Act (ACA), President Obama signed into law the Biologics Price Competition and Innovation Act of 2019 (BPCIA). Its purpose was to create an abbreviated approval path for biologic products that are highly similar (biosimilar) or interchangeable with an FDA-approved biological product.3

This act provided for two different approval pathways:

  1. Biosimilar and
  2. Interchangeable biosimilar


Out of the BPCIA came the Abbreviated Biologics License Application (ABLA), which was used instead of the Biologics License Application (BLA), by manufacturers who wanted to produce biosimilars.3

Like the ANDA for generic drugs, the ABLA created a passing lane on the approval roadmap; this time for biosimilars.

Drug manufacturers use the ABLA to provide comparison data that demonstrates biosimilarity in a stepped approach, as described by an FDA guidance document. An ABLA must meet rigorous approval standards to show biosimilarity to the reference product. In some cases, the FDA may ask for more data before approving an ABLA. (In contrast, the generic ANDA paperwork is specific and finite.)

The approved biosimilar and its reference product have no clinically meaningful differences. This includes dosage, form, safety, strength, route of administration, purity or potency.

The approved biosimilar and its reference product are highly similar, but not structurally identical.

Interchangeable biosimilars – a higher bar: An interchangeable biosimilar product has a much higher bar to meet. In addition to satisfying biosimilar requirements, the manufacturer of an interchangeable biosimilar must demonstrate that its product would produce the same clinical result as the reference product in any given patient. It must also demonstrate that switching between the interchangeable and reference product in a single patient would not increase the risk of safety issues or diminished efficacy, when compared with using the reference biologic product alone.4

An interchangeable biosimilar may be substituted at the pharmacy for the reference product without the intervention of the prescribing health care provider — much like how generic drugs are routinely substituted for brand-name drugs.

As of October 2022, three biosimilars had received interchangeability status: an insulin product, a drug used to treat certain inflammatory diseases, and a treatment for retinal patients. Eventually, there may be more.


The FDA collects user fees from drug manufacturers to review NDAs for new molecular entities (NMEs). Those fees are Prescription Drug User Fee Act (PDUFA). They help pay for achieving specific performance and processing goals, that include standardized review times. PDUFA user fees cover most human drugs and biological drug products. There are some exceptions.5 Fees collected under the Biosimilar User Fee Act (BsUFA) are for BLAs, similar to PDUFA, and in many cases are used interchangeably.

Today, PDUFA is often used as shorthand to refer to the estimated date when the FDA will issue its review decision.


The FDA issues a Complete Response Letter (CRL) if there are deficiencies in the application that prevent the approval of a drug or biologic product. The CRL will summarize the deficiencies and describe steps to remedy them.


The FDA issues a Refusal to File (RTF) when a new drug application (NDA) or biologics license application (BLA) is deemed incomplete. An RTF indicates that the agency has decided not to review the application. This allows the FDA to inform a manufacturer as quickly as possible of deficiencies in the application, rather than wait for the a CRL.

On the market today

As of February 2021, the FDA has approved 40 biosimilars; 27 of those have been launched.6

There will always be more to learn about the acronyms, nomenclature and product definitions making up the biosimilar drug content pipeline, but we hope this history was a helpful start.


  1. Hatch-Waxman Letters. 7-19-18. Accessed at:
  2. Generic Drug development. 6-6-19. Accessed at:
  3. Biosimilar Development Review and Approval. 10-17-21. Accessed at:
  4. Biosimilar and Interchangeable Products. 10-25-17. Accessed at:
  5. Performance Report to Congress for the Prescription Drug User Fee Act. FY 2019. Accessed at:
  6. FDA approved Biosimilar Products.

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