Understanding orphan drug regulations: an EU and U.S. comparative analysis.

Whereas orphan regulations exist in almost all ICH regions, they may correspond to significantly different types of reality in terms of principles and regulatory requirements. The apparent similarity in regulations may lead to misunderstanding and cultural gaps between sponsors and regulatory authorities. Based on the European and the US experience, we decipher the main points stumbling blocks that US sponsor may strike when applying for an orphan designation in the EU. An update of the orphan drugs designations is provided as well as the upcoming challenges that orphan regulations will meet with the development of pharmaco-genomics and personalized medicines.