Amgen, the world's largest biotech, has responded to the US Food and Drug Administration's recent draft guidance on biosimilars, saying "some changes and additional clarity are needed".

In February, the FDA issued three draft guidance documents on the regulation of biosimilars and Amgen says "we appreciate FDA’s commitment to working with stakeholders in a transparent guidance development process". The company then goes on to list a number of recommendations.

These include "defining ambiguous terms" and acknowledging and addressing "current technical and scientific limitations related to regulatory advice or requirements". Amgen also argues that any guidance needs to "make clear that clinical studies will be necessary for the foreseeable future due to the complexity and diversity of human biology and the limits of scientific knowledge today".

At the same time, the company adds, "it is appropriate for the agency to acknowledge that analytical studies will increasingly facilitate reduction in the size and scope of clinical studies needed". Other recommendations call on the FDA to publish "class-specific guidance that discusses the approval standards and other key implementation issues for particular product classes" and "require all biological products to have a distinguishable nonproprietary name in order to facilitate accurate attribution of adverse events".

Amgen says the FDA’s acknowledgement "that determining interchangeability is scientifically difficult at this time is also important". It adds that "patient safety does not stop at approval" and "distinguishable product names and post-approval activities, including ongoing monitoring, are essential".

Amgen is just one of 40 or so interested parties who have posted feedback on the FDA's plans ahead of a stakeholder meeting on May 11 to be held at agency headquarters in Silver Spring, Maryland.