Patent ID: 8518891

Claim:
A target-selective chemotherapeutic conjugate of a peptide substrate to a chemotherapeutic agent, said conjugate comprising a peptide covalently linked to the cytotoxic chemotherapeutic agent by a linker of formula: wherein X is N; R 1 and R 2 are independently selected from the group consisting of hydrogen, lower alkyl, alkoxyalkyl, amidoalkyl and carboxylalkyl; the terminal O on said linker forms a carboxylate, carbamate, phosphate, or phosphoramidate with said chemotherapeutic agent; and R is selected from the group consisting of F and Cl and n is 0, 1, 2, 3, 4; wherein said chemotherapeutic conjugate is less cytotoxic than said chemotherapeutic agent; said peptide substrate is subject to proteolytic cleavage by a tumor-specific enzyme; after which said linker undergoes 1,6-elimination in vivo to release said cytotoxic agent.