Replacing cholesterol with asiatic acid to prolong circulation and enhance anti-metastatic effects of non-PEGylated liposomes

Cholesterol is an indispensable component of most liposomes, heavily influencing their physical and surface properties. In this study, cholesterol in non-PEGylated liposomes was replaced by its analog, asiatic acid (AA), to generate liposomes with an alternative composition. These AA liposomes are generally smaller and more rigid than conventional liposomes, circulate longer in the body, and accumulate more in primary tumors and lung metastases in vivo. On the other hand, as an active ingredient, AA can decrease TGF-beta secretion to inhibit the epithelial-mesenchymal transition (EMT) process, increase the sensitivity of tumor cells to doxorubicin (DOX), and synergize with DOX to enhance the immune response, thus improving their antitumor and anti-metastasis efficiency. Based on this rationale, DOX-loaded AA liposomes were fabricated and tested against triple-negative breast cancer (TNBC). Results showed that compared with conventional liposomes, the DOX-AALip provided approximately 28.4% higher tumor volume reduction with almost no metastatic nodules in the mouse model. Our data demonstrate that AA liposomes are safe, simple, and efficient, and thus in many situations may be used instead of conventional liposomes, having good potential for further clinical translational development.