Novel anthracycline prodrugs

This paper highlights recent patents in the field of anthracycline prodrugs , which are employed in tumour-selective chemotherapy. The prodrugs can be a part of a two-step directed enzyme prodrug therapy (DEPT), which involves the localisation of the prodrug trigger at the tumour site, followed hy th e administration of the prodrug and subsequent tumour-selective anthracycli ne release. In most cases this trigger is an enzyme. which is indirectly lo calised by an antibody (ADEPT) or a gene encoding for an enzyme (GDEPT). Fu rthermore, anthracyclines can be targeted to the tumour site via prodrug mo notherapy. Anthracycline prodrugs exploiting differences in physiological c onditions, such as a lower pH and a lower oxygen tension in tumour tissue c ompared to healthy tissue, tumour-specific enzymes, such as plasmin, cathep sin B and beta -glucuronidase are discussed. Finally, prodrugs are reviewed that home to tumour-selective receptors. Promising advances in this field concern receptors that are required for angiogenesis.