[Chemosensitization with nitroimidazole to human gastric cancer transplanted into nude mice]

Combined chemotherapy for human gastric cancer Transplanted into nude mice has been performed to determine whether misonidazole (MIS) and metronidazole (MTR), derivatives of nitroimidazole, would enhance the antitumor activity of MMC. MTR, 500 mg/kg, MIS 500 mg/kg, and MMC 2.0 mg/kg were administered ip twice during a 48-hour interval. The antitumor efficacies of MMC only, MTR only, or MIS only were seen to be much the same as in the controls. The combined treatment with MMC and MTR surpassed the controls in antitumoral activity after the 12th day, whereas it did not surpass a regimen with MMC alone. The addition of MIS to MMC showed an enhanced antitumoral activity after the 10th day compared to the controls and, further, after the 10th day it exceeded the results of MMC only. Tumor tripling time in cases of MMC only, MTR only, MIS only, MMC plus MTR, and MMC plus MIS was 123, 132, 144, 144, and 178 hours, respectively, compared to 110 hours in the controls. Thus, these results suggest that MIS has a chemosensitizing activity under these conditions, while MTR has little activity.