Therapeutic peptides: technological advances driving peptides into development.

As potential therapeutics, peptides offer several advantages over small molecules (increased specificity) and antibodies (small size). Nevertheless, a number of key issues have hampered their use as drug candidates. A series of new technologies have recently been developed that allow peptides to be viable drug candidates in areas usually restricted to protein therapeutics, such as monoclonal antibodies. These include the development of various types of peptide-conjugates that have lower rates of clearance and hence the potential to increase the exposure of peptide drug candidates in chronic diseases. Structural additions have also been made to peptides, including the use of unnatural amino acids, mainchain modifications and other novel substitutions, which have helped to improve peptide stability and further their therapeutic potential.