<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A synthetic analogue of camptothecin with potential antineoplastic and radio-sensitizing activities. Camptothecin analogue TLC388 selectively stabilizes topoisomerase I-DNA covalent complexes during S-phase, thereby inhibiting religation of topoisomerase I-mediated single-strand DNA breaks and producing potentially lethal double-strand DNA breaks when encountered by the DNA replication machinery. Topoisomerase I relaxes negative super-coiled DNA during replication and transcription. This agent has been chemically modified to enhance the potency and stability of camptothecin.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>