Patent ID: 7115573

Claim:
A compound comprising: (1) a therapeutic agent capable of entering a target cell, (2) an oligopeptide of the formula (AA) n -AA 3 -AA 2 -AA 1 , wherein: AA 1 is selected from the group consisting of Leucine, Phenylalanine, Isoleucine, Alanine, Glycine, Tyrosine, 2-Naphthylalanine, Serine, Proline, and β-Alanine, AA 2 represents any amino acid, AA 3 represents isoleucine, n is 0 or 1, and when n is 1 then (AA) n is AA 4 which represents any amino acid, (3) a negatively charged stabilizing group, and (4) optionally, a linker group not cleavable by TOP, wherein: the oligopeptide is directly linked to the stabilizing group at a first attachment site of the oligopeptide and the oligopeptide is directly linked to the therapeutic agent or indirectly linked through the linker group to the therapeutic agent at a second attachment site of the oligopeptide, wherein the stabilizing group hinders cleavage of the compound by enzymes present in whole blood, and wherein the compound is cleavable by an enzyme associated with the target cell, the enzyme associated with the target cell being other than TOP, or a salt of said compound.