When the US Food and Drug Administration (FDA) approved the US' first biosimilar product, Zarxio, in March 2015, it gave the drug a unique and temporary nonproprietary name. Now a group of US senators is questioning whether FDA had the legal authority to do so.
Zarxio is the first drug to be approved under the 351(k) pathway created in 2010 under the Patient Protection and Affordable Care Act. The drug, which is manufactured by Sandoz, is intended to be biosimilar—not interchangeable—to Amgen's cancer drug Neupogen (filgrastim).
However, at the time of approval, FDA had still not finalized its biosimilar naming policy. The policy has been the source of a contentious debate within the biopharmaceutical industry.
Currently, both branded and generic chemical drugs share the same nonproprietary name, also known as its International Nonproprietary Name (INN). For example, both Advil and its generics are both known by the chemical name ibuprofen. This is meant to allow healthcare practitioners to readily assess which drug products are substitutable for one another in clinical practice.
But for biosimilar products, there's a problem. Unlike chemically derived generic drugs, which are supposed to be chemically identical to the drug they reference, it is all but impossible for biosimilar drugs to be identical to the approved biologic they reference. That’s because each product is derived from slightly different cell lines and is produced using slightly different manufacturing processes. While the ultimate products are highly similar, and may even have the same effect on patients, they are nevertheless not identical.
For some industry and patient groups, those differences are potentially concerning. Those minor differences, they say, could mean biosimilar products cause different adverse events in consumers. If biosimilars share the same INN with their reference biologics, pharmacovigilance—the practice of surveillance after a drug is approved—could be made more difficult for regulators, who might not recognize which product is causing a problem. The groups have argued that each biosimilar should have its own distinct nonproprietary name.
On the opposite side are some public advocacy groups and generics companies, which have argued the issue is a distraction. FDA is the ultimate arbiter of product safety, they say, and attempts to change the names of the products are in part intended to scare or confuse consumers about the quality of new biosimilar drugs.
A Unique Name
So when FDA approved Zarxio, some industry observers—including Regulatory Focus—expected FDA to simultaneously issue a guidance document on the naming of biosimilar products.
That didn't happen. Instead, FDA gave Zarxio what it called a "placeholder" name: filgrastim-sndz.
The name is a combination of Neupogen's nonproprietary name, filgrastim, and an abbreviation of Sandoz.
"The provision of a placeholder nonproprietary name for this product should not be viewed as reflective of the agency’s decision on a comprehensive naming policy for biosimilar and other biological products," FDA explained in a press statement at the time of Zarxio's approval. "While the FDA has not yet issued draft guidance on how current and future biological products marketed in the United States should be named, the agency intends to do so in the near future."
Indeed, FDA confirmed this week that its nonproprietary biologics naming policy should be finalized by the end of 2015.
In the meantime, the agency has started to include its "placeholder" name for Zarxio in its "Purple Book" listing of approved biologics and their biosimilar equivalents.
Now a group of senators is pushing back against FDA's placeholder naming strategy by raising questions about the agency's statutory authority to do so.
In a 30 April 2015 letter signed by 10 Republican members of the Senate Health, Education, Labor and Pensions (HELP) Committee, the legislators said they had "serious concerns" about FDA's implementation of the biosimilars pathway to date, and in particular FDA's placeholder name for biologics.
"It is unclear to us what it means for a nonproprietary name to be a 'placeholder,” what authority FDA has to make such a designation, or what treatment a 'placeholder' name will receive once FDA formalizes a naming policy," the senators wrote in their letter to Acting FDA Commissioner Stephen Ostroff. "In addition, we are concerned that hospitals, consumers, patients, doctors, and others may be confused by a name that appears temporary or not fully approved."
The letter goes on to ask FDA to clarify its legal authority to issue and change Zarxio's current "placeholder" nonproprietary name, as well as the process for changing the "placeholder" name in the future.
Such worries were not the only concerns raised by the legislators. The letter argued that much of FDA's existing guidance remains in "draft form."
"FDA’s failure to issue complete and final guidance before beginning to review and approve biosimilar applications raises significant questions," they wrote. "In particular, it is not clear to what extent FDA staff has been following draft guidance when reviewing biosimilar applications. And, if FDA staff has not been following draft guidance when reviewing applications, it is not clear what agency policies, if any, have been governing the process."
"FDA’s opaque implementation process is creating a troubling degree of uncertainty for patients, doctors, manufacturers, and other stakeholders who are invested in the success of this pathway," the senators concluded.
Letter to FDA