Nanotechnologies to use bisphosphonates as potent anticancer agents: the effects of zoledronic acid encapsulated into liposomes

Zoledronic acid (ZOL) is a potent amino-bisphosphonate used for the treatment of bone metastases with recently reported antitumor activity. However, the short plasma half-life and rapid accumulation in bone limits the use of ZOL as an antitumor agent in extraskeletal tissues. Therefore, we developed stealth liposomes encapsulating ZOL (LipoZOL) to increase extraskeletal drug availability. Compared to free ZOL, LipoZOL induced a stronger inhibition of growth of a range of different cancer cell lines in vitro. LipoZOL also caused significantly larger inhibition of tumor growth and increased the overall survival in murine models of human prostate cancer and multiple myeloma, in comparison with ZOL. Moreover, a strong inhibition of vasculogenetic events without evidence of necrosis in the tumor xenografts from prostate cancer was recorded after treatment with LipoZOL. We demonstrated both antitumor activity and tolerability of LipoZOL in preclinical animal models of both solid and hematopoietic malignancies, providing a rationale for early exploration of use of LipoZOL as a potential anticancer agent in cancer patients. FROM THE CLINICAL EDITOR: The short plasma half-life and rapid accumulation in bone limits the use of zoledronic acid as an antitumor agent in extraskeletal tissues. Therefore, stealth liposomes encapsulating ZOL (LipoZOL) have been developed to increase extraskeletal drug availability.