Concepts, Mechanisms, and New Targets for Chemotherapy describes new interconnections between rationally designed and empirically discovered compounds. One route that has not been travelled previously is that of protein kinase C inhibition. This pathway may be exploited to give potent inhibitors, such as the bryostatins, now in clinical trial. A summary is given of the current status of topoisomerase, focusing on recent clinical advances with camptothecin analogs based on connecting empiricism with concepts of drug selectivity. Modification of existing therapies based on the pursuit of leads arising from mechanistic studies is also being applied clinically on a wide scale. Greater understanding should follow from the studies