Biosimilars have become a hot topic recently, with drug prices soaring in the US and patients calling for cheaper alternatives to the brand name drugs that they are forced to buy. But the US is behind when it comes to biosimilars, with the FDA only approving its first in 2015. Europe, on the other hand, has had these drugs on the market for ten years.

Biosimilar drugs are replicas of biologics, which are much more structurally complex than other generic drugs. Biosimilar drugs have to be manufactured in living cells before being extracted and purified. Due to the greater complexity, and the more involved manufacturing process, it is not yet possible to make an identical copy of the original innovator drug, also known as the Reference Listed Drug (RLD). Biosimilars must, however, be highly similar to the RLD, with no clinically meaningful differences in safety or efficacy.

It can take up to fifteen years to develop a biosimilar product, and, on top of that, it is an expensive undertaking. But that hasn’t deterred drug manufacturers, and in fact, the FDA has a backlog of applications from companies trying to bring their newly developed biosimilar products to market

What, then, could explain why there are not more biosimilar products on the US market today?

The first issue is that the FDA has not provided clear guidelines. In 2010, with the passing of the Affordable Care Act, an abbreviated licensure pathway for biosimilars was created, streamlining the approval process for biosimilar products. However, the legislation simply states that these products have to be “highly similar” to the RLD, and does not give detail about what this actually means and how it can be proven.

Furthermore, the FDA has the authority to designate a biosimilar drug “interchangeable” with the innovator product, meaning a physician can prescribe the biosimilar drug, instead of the innovator, without having to seek approval. But, again, the FDA has yet to release official guidance on interchangeability, and has recently announced it will not release anything before the end of this year. As such, there is a lot of confusion around the process of seeking approval for these drugs.

The second issue is patenting. For companies that develop the innovator product, a biosimilar drug can mean unwelcome competition in the market place. These companies, therefore use the patents they were granted, for developing an innovator product, to keep biosimilar drugs off the market for as long as possible. Usually there are patents covering all aspects of the drug’s manufacture, formulation and indications, meaning that even as one patent expires, there are plenty more still in place. This can result in a situation in which a product is approved by the FDA but remains unavailable to patients for several months while patent issues are being resolved.

This is definitely a problem for biosimilar drug developers and, coupled with the unclear guidelines on the approval process for these biologics, it is not difficult to see why there are so few biosimilars on the US market.