Figure 2.

Examples of DOX prodrugs. Macromolecular DOX prodrugs are conjugated with polymer carriers, oligopeptides, with or without antibodies, which can combine with antigens located on the tumor cell surface and ligands that can be recognized by receptors on the tumor cell surface. Low molecular weight DOX prodrugs are combined with oligopeptides, with or without antibodies and ligands. DOX prodrugs remain inactive in blood vessels and normal tissues, but are cleaved by Cat B in tumor tissues and tumor cells, releasing free DOX, which results in targeted cytotoxicity. DOX, doxorubicin; Cat B, cathepsin B.