Doxorubicin is one of the most potent drugs for the treatment of small cell lung cancer (SCLC), but less potent for non-small eell lung cancer (NSCLC). The prevalent use of doxorubicin is limited by the development of cardiomyopathy. Therefore, TUT-7 SM-5887, and ME2303 have been under the clinical studies to find new anthracyclines with less cardiotoxicity and higher therapeutic indices not only for SCLC but also for NSCLC. The dose-limiting factor of these drugs determined in phase I studies was leukocytopenia. Phase II studies which are currently under way have indicated that SM-5887 is possibly most potent for the treatment of NSCLC, and that these drugs have less cardiotoxicity compared to the mother compound, doxorubicin.