Antitumor effects of rhodium (II) citrate in mice bearing Ehrlich tumors

Rhodium II citrate was tested in mice for acute toxicity, antitumoral activity against Ehrlich ascites carcinoma and inhibition of DNA synthesis by Ehrlich tumor, malignant adrenocortical cells (Y-1) and normal adrenocortical cells (AR-1). At ip doses up to 260 mg/kg, the compound had no toxic effects for up to 14 days. The same total dose given over 4 days significantly increased the survival rate of mice bearing Ehrlich ascites cells. Thymidine incorporation by Ehrlich tumor, Y-1 and AR-1 cells in vitro was inhibited 50% by 0.1 to 0.2 mM concentrations of the compound. We conclude that the increased survival of the tumor-bearing mice was due at least in part to the inhibition of DNA synthesis with a consequent reduction of cell division and tumor growth.