A bifunctional nitrogen alkylating agent with antineoplastic activity and lipophilic properties. Containing a lipophilic hydantoin group that serves as a carrier to cross the blood brain barrier, spiromustine forms covalent linkages with nucleophilic centers in DNA, causing depurination, base-pair miscoding, strand scission, and DNA-DNA cross-linking, which may result in cytotoxicity. Check for active clinical trials using this agent. (NCI Thesaurus)