Antitumor activity of a new fluoropyrimidine derivative, 5'-deoxy-5-fluorouridine, against murine and human experimental tumors.

5'-Deoxy-5-fluorouridine (5'-DFUR) was evaluated for antitumor activity against four murine tumors (L1210 leukemia, P388 leukemia, Lewis lung carcinoma, and B16 melanoma) and a human mammary carcinoma (MX-1) xenografted in athymic mice. Intraperitoneal administration of 5'-DFUR was ineffective against B16 melanoma implanted intraperitoneally and showed less marked antitumor activity against P388 and L1210 leukemias implanted intraperitoneally or intravenously as compared with that of 5-fluorouracil (5-FU) or 1-(2-tetrahydrofuryl)-5-fluorouracil (FT-207), while oral administration of 5'-DFUR showed a similar or superior antitumor activity to that of 5-FU or FT-207 against L1210 leukemia implanted subcutaneously. 5'-DFUR showed a marked antitumor activity against MX-1 implanted subcutaneously and also showed slight antitumor activity against Lewis lung carcinoma implanted subcutaneously, while 5-FU and FT-207 did not show any significant antitumor activity against these tumors. These results suggest that 5'-DFUR may be worthy of clinical trial against solid tumors, especially cancers of the breast.