A hydrochloride salt of esorubicin, a derivative of the anthracycline antineoplastic antibiotic doxorubicin, with potential antineoplastic activity. Esorubicin intercalates into DNA and inhibits topoisomerase II, thereby inhibiting DNA replication and ultimately, interfering with RNA and protein synthesis. This agent exhibits less cardiotoxicity than the parent antibiotic doxorubicin, but may cause more severe myelosupression compared to other compounds within the anthracycline class.