How Are Biosimilars Named and Identified?

When conventional small molecule agents are approved, the United States Adopted Names (USAN) Council assigns a nonproprietary (generic) name identifying the active medication. Similar to conventional small-molecule medications, newly approved biologics are given both a brand name (e.g., Neupogen) and a nonproprietary (proper) name (e.g., filgrastim). The nonproprietary name reflects certain scientific characteristics of the product, such as chemical structure and pharmacological properties. Because medications may be approved for use in many countries around the world, the generic name assigned by the USAN Council usually is adopted by the World Health Organization (WHO) as the International Nonproprietary Name (INN). The INN facilitates the clear identification of medications, safe prescribing and dispensing of medications, and communication and exchange of information among health care professionals and scientists worldwide.

Specific rules for assigning nonproprietary names for biosimilar products in the United States had not been fully established when the first products were approved. The first biosimilar product (Zarxio) was given a placeholder nonproprietary name of filgrastim-sndz. The FDA assigned a random 4-letter suffix to the second biosimilar approved, infliximab-dyyb.

In a final guidance for industry issued in January 2017, the FDA established that all reference products and biosimilars will have a two-part nonproprietary name, consisting of:

  1. A core name that will be the same for all products.
  2. A distinguishing suffix that is devoid of meaning and composed of four lowercase letters, separated from the core name by a hyphen.

For example, the nonproprietary name of a reference product could be replicamab-cznm, and a biosimilar to that product could be replicamab-hixf. At least three of the four lowercase letters in the suffix must be distinct.

These requirements will necessitate changes in the names of a number of approved products. For example, filgrastim (Neupogen; Amgen) will get a suffix. Filgrastim-sndz (Zarxio: Sandoz) will lose its “meaningful” suffix, which was derived from the name of the manufacturer. Etanercept-szzs (Erelzi; Sandoz) will need a new suffix that has at least three distinct letters. The guidance does not specify a timeline for changing the nonproprietary names of previously approved biologics.

The guidance also does not include a naming convention for interchangeable products.