Editor’s note: Shortly after completion of this article, Hubert Chen stepped down as CMO and CSO of Pfenex. He remains a medical and scientific advisor to the company.
The biosimilar regulatory space has been alive with conversations the last few months. One U.S. regulatory topic I have yet to discuss at length — and one that currently raises more questions than answers — is the FDA’s 505(b)(2) pathway. This pathway was created primarily to support the approval of new indications, routes of delivery, or sustained- release versions of existing drugs. However, it also has been leveraged to support the approval of follow-on, or “generic” versions, of biologics — for instance, growth hormone, insulin, and teriparatide — that were originally approved via an NDA as opposed to a biologics license application (BLA). While these follow-on biologics are not considered biosimilars, these same molecules are approved as biosimilars in the EU, Japan, Canada, and pretty much everywhere else in the world. Not only is this a confusing pathway to understand because of these designation differences, but it’s also facing a particularly big change. Come March 2020, the FDA plans to phase out this particular pathway for most follow-on biologics to ensure harmonization with the 351(k) biosimilar pathway. Recombinant peptides that are less than 40 amino acids in length are exempt from the switch.