Studies in a tumor spectrum. III. The effect of phosphoramides on the growth of a variety of mouse and rat tumors.

Previous investigations with a spectrum of tu mors demonstrated that nitrogen mustards (17) and triethylene melamine (19) had a definite in hibitory or destructive action on certain types of tumors. In view of the fact that the biological ac tivity of these compounds is believed to be due to the formation of ethylenimmonium ions in the case of the former (7) and the presence of ethylenimine groups in the case of the latter, the study was extended with compounds closely related to these substances on a wide spectrum of tumors. Results in experimental animal tumors reported from other laboratories (1-3, 6, 9-11, £0, 21) and in human cancer (4, 8, 20) have indicated that tri ethylene phosphoramide and triethylene thiophosphoramide merited intensive study. Our observa tions on the effect of these compounds on a variety of transplantable mouse and rat tumors have been briefly reported (14, 18) and are now presented in more detail. The structural formulae of these com pounds have in common the cyclic structure, ethylenimine :