Antitumor effect of the angiogenesis inhibitor TNP-470 on human digestive organ malignancy

The antitumor and antimetastatic effects of TNP-470, an angiogenesis inhibitor, on human gastrointestinal tumors xenotransplanted into nude mice were investigated. When two gastric cancer (MT-2 and MT-5) and two colon cancer (TK-4 and TK-13) xenografts are transplanted orthotopically into nude mice, liver metastasis develops 6 weeks after transplantation. TNP-470 30 mg/kg had a significant inhibitory effect on primary tumor growth of gastric cancers when given on alternate days from 7 days after transplantation. However, when given from 10 days or 14 days after transplantation, no inhibitory effect on the growth of any tumor xenograft was observed. In contrast, liver metastasis of each xenograft type was inhibited significantly by TNP-470. The effect of TNP-470 on prognosis was investigated using a hepatic metastatic model of rat hepatoma. Although all untreated rats that received AH-130 cell implants died within one month of massive hepatic metastasis, > 50% of rats treated with TNP-470 survived for 4 months. The number of apoptotic cells in hepatic metastatic foci was significantly increased by TNP-470 administration. These results suggest that TNP-470 may provide a new approach to the treatment of digestive organ malignancies.