Oxidatively activated DNA-modifying agents for selective cytotoxicity.

DNA-modifying agents are stalwarts of chemotherapeutic cancer treatments, but require significant design improvements to improve selectivity, minimize side effects, and for their widespread use to continue. Herein we present a novel design strategy in which DNA-modifying agents contain an oxidizable leaving group and a nitrogen mustard. The agents form strong electrophiles specifically when oxidized. Activation, measured by hydrolysis, illustrates that oxidants increase reactivity 1700-fold. Reaction in the presence of 2'-deoxyguanosine leads to the formation of lesions. Cytotoxicity measured in HeLa cells showed that low IC(50) values require an oxidizable hydroquinone and a nitrogen mustard fragment. Cytotoxicity measurements in 15 cancer cell lines demonstrates that oxidatively activated DNA-modifying agents are highly selective, as the analogue tested has IC(50) values less than 10 μM for only three of the 15 cell lines; in contrast, cisplatin is highly toxic to 13 of the 15 cell lines. The selective cytotoxicity of oxidatively activated DNA-damaging agents could be useful against kidney cancer cells, as the 786-O cell line model assay resulted in an IC(50) value of 5 μM.