The dimethyltriazenes p-(3,3-dimethyl-1-triazeno)benzoic acid potassium salt (DM-COOK) and 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC) increase, unlike cyclophosphamide (Cy), the survival time of mice bearing L1210 lymphoid leukemia, P388 lymphocytic leukemia and TLX5 lymphoma with a mechanism unrelated to cytotoxicity for tumor cells. The in vivo bioassays of brains, and the histologic examinations of the livers of leukemic mice show that DM-COOK and DTIC prevent leukemic infiltration in these organs at dosages devoid of cytotoxic effects for peritoneal tumor cells. At a dosage equitoxic with that of dimethyltriazenes, cyclophosphamide causes the absence of tumor cells in the peritoneal cavity and in the brains and livers of mice bearing P388 and L1210 leukemias. DM-COOK and DTIC thus possess a mild or insignificant cytotoxic action together with antimetastatic properties also on mouse transplantable leukemias. The use of DM-COOK appears advantageous over that of cyclophosphamide and DTIC because of a reduced host toxicity, which is particularly evident for cyclophosphamide and DTIC on liver parenchyma and bone marrow.
