The US FDA has proposed changes to its nonproprietary naming guidance to remove the proposed controversial four-letter suffix from older biologics.

In 2017, the US Food and Drug Administration (FDA) published guidance to include a random four-letter suffix to the international nonproprietary names (INN) of all biological products. The ruling essentially distinguished a biosimilar from its reference product, so Amgen’s reference product Neupogen, for example, is known as ‘filgrastim-jcwp,’ while Sandoz’s biosimilar version Zarxio – the first biosimilar approved and launched in the US – is known as ‘filgrastim-sndz.’

Products approved under section 505 of the Federal Food, Drug, and Cosmetic Act (FD&C Act) rather than the designated 351(k) biosimilar pathway, such as Teva’s Granix, has also had its license name changed to ‘filgastrim-vkzt.’

But now the Agency, in a draft update to the 2017 guidance, is potentially partially reversing its naming procedures and “no longer intends to modify the proper names of biological products that were licensed under the Public Health Service (PHS) Act without an FDA-designated suffix in their proper names,” as well as not intending “to apply the naming convention to the proper names of transition biological products.”

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The Agency is also reconsidering whether vaccines should be within the scope of the naming convention, it said in the guidance document.

However, all interchangeable biosimilars approved through the 351(k) pathway will have the suffix, as the “FDA believes a distinguishing suffix is necessary to achieve adequate pharmacovigilance for these products.

“A unique suffix will facilitate manufacturer-specific pharmacovigilance by providing a means of determining which biological product is dispensed to patients when other means to track this information are not readily accessible or available. Use of a distinguishing suffix will also avoid the need for changes to the nonproprietary name of a biological product that is first licensed as a biosimilar product and later determined to be an interchangeable product.”

As yet, none of the now 18 approved biosimilar products in the US have been deemed interchangeable by the Agency.

Biosimilar, bio-distinguished

The idea behind the four-letter guidance was, according to the FDA, to provide “robust identification and tracking systems to ensure safe dispensing practices and optimal pharmacovigilance.”

However, some physician groups and biosimilar industry greeted the distinguishable INN guidelines with disdain, describing the suffix as “meaningless” and – a Sandoz representative told this journalist back in 2016 – “almost a little comical” with “a lot of time being spent on it when essentially the product is the same.”

The US is the only country to differentiate between a reference product and its biosimilars through nomenclature, with Canada abandoning the policy last month.

“Following internal and external stakeholder consultations and analysis of related issues, Health Canada has decided that biologic drugs, including biosimilars, will be identified by their unique brand name and non-proprietary (common) name, without the addition of a product-specific suffix,” Health Canada wrote.

“Both the brand name and non-proprietary name should be used throughout the medication use process so that biologics that share the same non-proprietary name can be distinguished by their unique brand names.”