Fluorinated Pyrimidines VI. Effects of 5-Fluorouridine and 5-Fluoro-2′-Deoxyuridine on Transplanted Tumors. ∗ †

Summary

1. Activity of 5-fluorouridine (FUR) and 5-fluoro-2′-deoxyuridine (FUDR) against several transplanted tumors has been compared with that of 5-fluorouracil (FU). 2. In Adenocarcinoma 755 and L-1210 leukemia FU is more effective than either nucleoside, although the latter have significant tumor-inhibitory activities. 3. In Sarcoma 180, FUDR is much more effective than FU; FUR has no significant activity. 4. In the Ehrlich ascites carcinoma, both nucleosides are more effective in prolonging life than is 5-fluorouracil, with FUR demonstrating activity at a low dose. In a 5-fluorouracil-resistant line of the Ehrlich ascites carcinoma, 5-fluorouridine is as active as in the parent strain. 5. In mice, the toxicity by repeated doses of FUR is much greater than that of FU; FUDR is less toxic than FU. In rats, the toxicity of FUR is much less pronounced than in mice, and the compound was very effective in inhibiting the growth of the Novikoff hepatoma.