Liposomal encapsulated anthracyclines: new therapeutic horizons

After two decades of work in liposomal formulations for clinical use, two preparations containing doxorubicin (Doxil, ALZA, Pablo Alto, CA; and Evacet, The Liposome Company, Princeton, NJ), and one containing daunorubicin (DaunoXome; Gilead Sciences, Foster City, CA) have been undergoing widespread clinical study. Results have lived up to the promise that liposomal encapsulation may lead to toxicity attenuation, while retaining or even enhancing the efficacy of the parent anthracyclines. The eventual role of these agents in clinical practice is being defined in a number of studies that are reviewed herein. Already, approved indications have been achieved for doxorubicin against Kaposi's sarcoma and ovarian cancers, and for daunorubicin against Kaposi's sarcoma. The three compounds vary widely in their pharmacology, and these differences may contribute to their preferential localization into certain tumors. Additional indications for these liposomal encapsulated anthracyclines are likely to be established in the ensuing years.