The complex of
poly(I):
poly(C) and a new cationic
liposome (LIC) has a potent antitumor activity against many tumor cell lines in vitro, whereas
poly(I):
poly(C) itself has no such activity. In the present study we tested the sensitivity of 21 human colon and
pancreatic cancer cell lines to LIC or
Adriamycin in vitro. The growth of most of the cell lines was strongly inhibited by both LIC and
Adriamycin in vitro, although a few insensitive cell lines were different. We also studied the in vivo antitumor activity of LIC or
Adriamycin in three experimental liver
metastasis models in nude mice using a human
pancreatic cancer cell line (AsPC-1) and two human
colon cancer cell lines (Ls174T and HCC-M1544). The administration of LIC or
Adriamycin was started 3 days after the injection of
tumor cells. Animals received 0.1 mg/kg LIC IV twice weekly or 5 mg/kg
Adriamycin IV every 5 days during the experiments. LIC showed potent antitumor activity in all three
liver cancer models. Although
Adriamycin had potent antitumor activity in the HCC-M1544 model, it had only a moderate effect in the AsPC-1 model and at most a weak effect in the Ls174T model. At the effective doses LIC did not cause detectable pathological changes in the liver and did not elicit toxicity to mice in these models, whereas
Adriamycin did exhibit toxic effects. These results suggest that LIC is a promising candidate
drug to treat hepatic
metastasis.