Liver metastases from colorectal cancer: drug delivery with liposome-encapsulated doxorubicin.

Abstract

To evaluate the intratumoral distribution of liposome-encapsulated doxorubicin. Tumor-bearing livers of 24 mice were studied with in vivo fluorescence and electron microscopy after injection of liposomal doxorubicin in the hepatic artery, portal vein, or tail vein. Distribution and uptake of liposomes and doxorubicin in tumors were compared at 5, 30, and 60 minutes after injection. In vitro evaluation of uptake of doxorubicin in Kupffer cells and in human colorectal cancer cells incubated under normoxic and hypoxic conditions for 5, 30, and 60 minutes was performed with fluorescence microscopy. Doxorubicin autofluorescence was seen in tumors 30 minutes after intraarterial and intraportal injection and was statistically significantly greater at 60 minutes (P < .001). Liposomes were observed in small tumors (diameter < 300 microns) and were trapped in Kupffer cells around larger, hypovascular tumors. Electron microscopy findings confirmed intracytoplasmic, perinuclear uptake of liposomes in tumor cells. In vitro, a higher proportion of doxorubicin was seen in cancer cells (92%) than in Kupffer cells (75%) after 60 minutes incubation. Liposomal doxorubicin can be reliably delivered to liver metastases via the hepatic artery, eliminating need for tumor embolization. Further evaluation is warranted, and the drug may be useful for treating patients with unresectable liver metastases.