Antitumor effect of some rhodium(I) derivatives on MCa mammary carcinoma.

The antitumor action of two square planar Rhodium complexes was tested on MCa mammary carcinoma and was seen to depend upon the compound used. The complex cyclooctadiene(2-pyridinalmethylimine)-Rh(I)chloride [Rh(COD)PMI]+ Cl- confirmed the antineoplastic action already shown in the Lewis lung carcinoma model. The examination of the activity of [Rh(COD)PMI]+ Cl- on the lung metastatic tumor indicates that its antineoplastic properties do not seem simply related to a cytotoxic action. It appears more likely that modifications occurring at the primary tumor level, probably different from lethal effects directed to tumor cells, are responsible for the reduction of spontaneous lung metastasis formation observed in the treated animals. The trophic effects observed on the spleen of the treated animals seem to suggest that these compounds are endowed with properties typical of biological response modifiers.