Bicyclic Peptides - Emerging Class Of Drugs

By Archana Gangakhedkar, Technical Marketing Specialist, American Peptide Company, Inc.

Bicyclic peptides are an emerging class of peptide molecules used to explore new cellular sites which are undruggable by small molecules or by large antibodies. Bicyclic peptides have some favorable properties when compared to current drug classes and will likely open a new path for targeting diseases.

Drugs approved by the Food and Drug Administration (FDA) or regulatory agencies worldwide fall under two main categories: small molecules and biologics or large proteins. Both of these classes experience limitations that restrict their functional range.  Small molecules target human proteins bearing lipophilic pockets on their surface while large proteins and antibodies target through the exterior of the cell, so both of the drug classes do not interact with the targets inside the cells. Both small molecules and larger proteins together can access only 25% of cell targets and the other 75% of human proteins inside the cell are not targeted by these two classes of drugs, making these cellular sites undruggable. There is a great deal of interest among researchers to target these undruggable sites through the development of a novel therapeutic class, such as bicyclic peptides, that lie between the small molecule and monoclonal antibody (mAb) drug classes.