The effects of 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC) and its benzenoid analog p-(3,3-dimethyl-1-triazeno)benzoic acid potassium salt (DM-COOK) have been examined in mice bearing two Lewis lung carcinoma lines with different potential to spontaneously metastasize to the lungs. DTIC similarly depresses the growth of intramuscular and pulmonary tumor nodules, and also reduces the development of spontaneous lung metastases for both tumor lines. DM-COOK causes effects similar to those of DTIC on the tumor line with low metastatic potential; on the contrary, although it is highly active in inhibiting lung metastasis formation for the line with high metastatic potential, it is ineffective or marginally cytotoxic on intramuscular or on pulmonary tumor nodules, respectively. These data indicate, at least for the dimethyltriazene DM-COOK, a dissociation between sensitivity to cytotoxic and antimetastatic effects, and that tumor cell populations with a higher potential to spontaneously metastasize have a greater sensitivity to selective antimetastatic effects, concomitant with a reduced cytotoxic response to the effects of this drug.
