Angiogenesis inhibitors have attracted considerable interest. The anti-tumor and anti-metastatic effects of TNP-470, an angiogenesis inhibitor, and mitomycin C (MMC), a representative anti-neoplastic agent, were investigated using a xenotransplanted human colon cancer, TK-4. Suturing of small pieces of TK-4 tumors to the cecal wall in nude mice (orthotopic transplantation) induced liver metastasis. Mice were randomly divided into 3 groups; a control group given saline solution, a group receiving TNP-470 and a group receiving MMC. TNP-470 was given s.c. on alternate days for 5 weeks from day 10 after cecal transplantation and MMC was administered intraperitoneally (i.p.) once a week from day 10 after cecal transplantation. MMC significantly inhibited cecal tumor growth. In the control group, liver metastases developed in 9 out of 10 mice, including 3 with more than 20 metastatic foci. Liver metastasis also developed in 8 out of 10 mice receiving MMC, 2 of which had many metastases. In contrast, liver metastasis developed in only 2 out of 8 mice in the TNP-470 group and neither of these animals had numerous metastases.

Adriamycin (ADM) was encapsulated in a galactose-conjugated hepatotropic liposome (hLip-ADM) and its ability to enhance the antitumor effect while reducing toxicity was compared with that of free ADM and a control Lip-ADM (cLip-ADM), in two in vitro animal models. Liver metastases were induced in rats by an intravenous injection of 8 x 10(6) AH-130 rat hepatoma tumor cells. All forms of the ADM completely inhibited liver metastasis when given at a dose of 5 mg/kg on day 14 after tumor implantation, whereas liver metastatic foci were observed in six of ten rats in the control group. The reduction in ADM toxicity by liposomalization was remarkable, as significant body weight loss was observed only in the free ADM group, in which four of ten rats died. Additional experiments utilized a human colon cancer xenograft (TK-4) to induce the growth of the liver metastases in mice by orthotopic implantation. The hLip-ADM completely inhibited liver metastasis in rats (0/11), whereas liver metastases developed in 10 of 12 mice in the control group and in 5 of 12 mice given cLip-ADM. Interestingly, liposomal ADM did not have a significant inhibitory effect on transplanted tumor growth assessed 6 weeks after transplantation. These findings indicate that hLip-ADM may be an effective strategy for inhibiting liver metastases from human colon cancer.

We established a mouse "primary tumor resection model" in which a transplanted tumor was resected after an orthotopic transplantation of colorectal cancer tissue to estimate the therapeutic effect of an angiogenesis inhibitor on metastasis. The angiogenesis inhibitor FR-118487 is a member of the fumagillin family. Here, 1 mg/kg/day of FR-118487 was subcutaneously administered to nude mice for 1 week, 2 weeks, or 4 weeks through an osmotic pump. Liver metastasis developed in 7 of 9 control mice, 2 of 6 mice that underwent the tumor resection 2 weeks after transplantation (early resection), and in all 7 of the mice that underwent the tumor resection 4 weeks after transplantation (late resection). In the short treatment trial, the FR-118487 administration immediately after the early resection completely inhibited both hepatic and peritoneal metastases, whereas its administration after the late resection had no effect on liver metastasis. In the prolonged treatment trial, inhibitory effects of prolonged treatment with FR-118487 on both hepatic and peritoneal metastases after the late resection were clearly demonstrated. The mice of the resection-alone group all died within 106 days after tumor inoculation, due to metastases of colon carcinoma. In contrast, half of the mice that underwent resection and then received antiangiogenic therapy were alive at the end of the observation period (160 days after transplantation). In conclusion, the combination of surgery and subsequent antiangiogenic therapy may be useful to prevent the distant metastasis of colorectal cancer and to improve the prognosis of patients with colorectal cancer. Key words: Hepatic metastasis -Metastasis after surgery -Human colon cancer -Angiogenesis inhibitor -Tumor removalHepatic metastasis is the most common cause of death after surgery for patients with colorectal cancer, and methodologies to prevent liver metastasis after surgery have been sought to improve the prognosis of these patients. There are no reports of a liver metastasis model after the resection of a primary colorectal tumor, to our knowledge. We established such a metastatic model, which well reflected the clinical situation, in which hepatic metastases developed after the removal of transplanted orthotopicallygrowing colorectal tumor. Accordingly, the results obtained in this model are thought to be of relevance to the clinical situation. With this model, therapeutic effects of antiangiogenic therapy followed by surgery on human colon cancer have been investigated.Tumor neovascularization is part of the complicated process of tumor metastasis, 1) and is crucial to the occurrence of hepatic metastasis.2) Since a small focus of tumor cells cannot grow indefinitely at a secondary site without the induction of angiogenesis, it is speculated that the inhibition of angiogenesis could provide a potent form of therapy for the hepatic metastasis of colonic cancer.3) Many studies have demonstrated the essential role of angiogenesis in the aggressive growth of solid tumors and their metastases.

A liposome-entrapped liposome form of Adriamycin (Lip-ADM) has been demonstrated to cause less myocardial and gastrointestinal toxicity than free ADM. In the present study, Lip-ADM prepared by the remote loading method was administered to 3 patients with metastatic adenocarcinoma of the liver via a reservoir with the catheter located in the proper hepatic artery. The primary tumor was gastric cancer in 2 patients and sigmoid colon cancer in 1. Lip-ADM was administered at doses of 10, 20 or 50 mg per time. The total ADM dose was 170, 490, and 760 mg, respectively. No severe adverse effects, such as nausea, vomiting, stomatitis, alopecia or cardiotoxicity, were observed in any of the patients. Although mild leukocytopenia (2,800/µl) was observed in 1 patient, anemia or thrombocytopenia did not occur. The survival time was respectively 6,15, and 17 months from the start of Lip-ADM administration. A partial response was obtained in 1 patient and stable disease in 1 patient. Administration of Lip-ADM via a reservoir appears to be a useful treatment for patients with metastatic adenocarcinoma of the liver, since the low toxicity of this preparation allows an increase of the total dose of ADM.

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