The US Food and Drug Administration (FDA) has issued new guidance documents to help the biopharmaceutical industry develop biosimilar versions of some expensive brand name drugs in the US.
A regulatory pathway to bring equivalent versions of off-patent biologic drugs to market has existed in principle in the US since March 2010, but developers have been waiting for guidance from the FDA to make sure their drug candidates meet the agency's requirements.
The complex nature of biologics means that unlike their small-molecule chemical cousins it is practically impossible to duplicate a drug entirely, as even a single manufacturer's product will exhibit variations between production runs.
The US is lagging behind other regions in the development of a biosimilar market, however, including the EU which has had biosimilars on the market for several years.
The director of FDA's Centre for Drug Evaluation and Research, Janet Woodcock, said that the agency has tried to develop guides to support biosimilar development "at every step of the process".
Three documents have been prepared and published for comment by the public.
The first covers scientific guidance on how to demonstrate that a therapeutic protein product is biosimilar or equivalent to the original reference product, while the second covers the analytical and quality factors that can be used to assess biosimilarity.
The third guidance takes the form of a question and answer document to give advice on the biosimilar development process, including how to request meetings with the FDA, addressing differences in formulation from the reference product, how to request exclusivity, and other topics.
A fourth document is also promised, and will cover the standards that need to be met to allow substitution of a biosimilar for the branded product.
"These draft documents are designed to help industry develop biosimilar versions of currently approved biological products, which can enhance competition and may lead to better patient access and lower cost to consumers," said Woodcock.
The over-arching tone of the documents is that the FDA will assess biosimilar applications on a case-by-case basis - which has the advantage of not locking developers into a particular approach - with a strong emphasis on discussion and collaboration with the agency at an early stage.
On the other hand, a lack of detail may discourage some firms from making the considerable investment required to develop a biosimilar, even with an abbreviated regulatory pathway.
The FDA recently published details of its user fee programme for generic medicines - including biosimilars - which will help define and fund its activities in this area.
Meanwhile, evolution of biosimilar regulations is continuing in the EU, where a final guideline on biosimilar monoclonal antibodies is expected within the next couple of months.