Effects of N-Methylformamide and Related Compounds in Mouse Sarcoma 180. ∗

Summary and Conclusions

1. Formamide and its more potent N-methyl derivative have been described as transient inhibitors of the growth of mouse sarcoma 180. This effect is not a property of formamides in general since other compounds containing the formamide moiety have failed to affect the growth of the tumor. 2. N-methylformamide has been shown to exert its effects when therapy is started either 24 or 96 hours after implantation of the tumor or when the agent is given in a single, large dose. Further, the compound has been found equally effective whether given by the oral or intraperitoneal route. 3. Histologic changes of a non-specific nature have been described in tumors from animals treated with N-methylformamide. 4. In view of the structural resemblance between formamide and urethane, the actions of both agents have been compared. Urethane, like formamide, inhibits the growth of S-180; however, treatment with the former substance causes toxic manifestations not encountered in mice given formamide. 5. Several conceivable mechanisms have been proposed to account for the inhibitory effects of the formamides. Further studies of these suggested modes of action may provide useful information concerning biochemical mechanisms involved in the growth of tumors. 6. In view of the hepatotoxicity of formamide and its N-methyl derivative it is not expected that these agents will prove therapeutically useful.