Experimental studies on the antitumor effect of ethidium bromide and related substances.

The antileukemic activity of ethidium bromide, an inhibitor of RNA-dependent DNA polymerase activity, and of 14 related agents newly synthesized was tested in experimental tumor systems. Ethidium bromide caused up to 200% increased life-span in mice with 6C3HED-OG and 83% increased life-span in mice with L5178Y. No substantial percentage of increased life-span was noted in rodents with L1210, 6C3HED-RG, EL4, RADA,, and Walker carcinosarcoma 256. Of the 14 related substances tested, PD-MY-001 and PD-MY-003 also increased the survival time of mice with 6C3HED-OG up to 200%. Ethidium bromide and these two newly synthesized substances are considered to be antitumor agents with a unique mechanism of action.