Antitumor activity of 1-alkylcarbamoyl derivatives of 5-fluorouracil in a variety of mouse tumors.

The antitumor properties of 1-alkylcarbamoyl derivatives of 5-fluorouracil were examined in various mouse tumor systems to select promising compounds for clinical use. Almost all alkylcarbamoyl derivatives were active against various tumors when given by oral administration. Among them, 1-methyl, 1-ethyl, 1-isopropyl, 1-hexyl and 1-octyl carbamoyl derivatives of 5-fluorouracil were moderately or markedly active in six mouse tumor systems tested. However, 1-methyl, 1-ethyl, and 1-isopropyl carbamoyl derivatives were toxic to mice, though not lethal. As a result, 1-hexyl and 1-octyl carbamoyl derivatives were selected as the best candidates for antitumor agents in further study.