Prodrugs cleavable by CD26

The present invention provides a new prodrug technology and new prodrugs in order to increase the solubility, to modulate plasma protein binding or to enhance the biovailability of a drug. In the present invention the prodrugs are conjugates of a therapeutic compound and a peptide (eg tetrapeptide or hexapeptide) wherein the conjugate is cleavable by dipeptidyl-peptidases, more preferably by CD26, also known as DPPIV (dipeptidyl aminodipeptidase IV). The present invention furthermore provides a method of producing the prodrugs, to enhance brain and lymphatic delivery of drugs and/or to extend drug half-lives in plasma.