[Experimental study on the combined treatment of UFT with etoposide against mouse Lewis lung carcinoma]

Synergistic cytotoxicity between FUra and etoposide was determined in Lewis lung carcinoma (3LL) cells by clonogenic assay. With the same exposure condition, chasing the time course of DNA strand breaks and repair by DNA unwinding assay. DNA repair in the exposure sequence of etoposide prior to FUra was remarkably delayed more than that by etoposide alone. There was a little overlap in normal tissue toxicity of UFT and etoposide since 65% of the full dosages of the two agents can be used in combination and main toxicities (suppression of body weight, decrease in WBC and damage of intestinal mucosa) were dispersed with dependence on the schedule of administration. Moreover, this combined treatment with the most tolerated dose resulted in the highest survival effect on 3LL-bearing mice than each agent alone. These data suggest that combination chemotherapy of UFT with etoposide show high antitumor activity and low host toxicity, and will be clinically useful.