Efforts are ongoing to improve the therapeutic index of anticancer agents, either by increasing the drug concentration inside the tumor or by decreasing it in normal host tissues [10] . Compared with conventionally administered chemotherapeutic agents, lipid-or polymer-based nano-medicine drug delivery systems have the advantage of improving the pharmacological and therapeutic properties of cytotoxic drugs [11] . Most smallmolecule chemotherapeutic agents have a large volume of distribution on intravenous administration [12] and a narrow therapeutic window due to serious toxicity to normal tissues. By encapsulating drugs in nano-particles such as liposomes, scientists can significantly reduce the volume of distribution and increase the concentration of active drug within the tumor [13] . PEGylated liposomal doxorubicin (with brand names of Doxil in the US and Caelyx in Europe) [14] has been shown to significantly improve the therapeutic index of doxorubicin both in preclinical [15] [16] [17] and clinical studies [18] [19] [20] [21] . Several drug delivery systems of this kind have been approved for marketing [22, 23] .