Methods for administering mitomycin C to a multi drug resistant cell and for reducing the toxicity of the compound are described. In the methods, mitomycin C is provided in the form of a prodrug conjugate, where the drug is linked to a hydrophobic moiety, such as a lipid, through a cleavable dithiobenzyl linkage. The dithiobenzyl linkage is susceptible to cleavage by mild thiolysis, resulting in release of mitomycin C in is original from. The linkage is stable under non reducing condition. The prodrug conjugate can be incorporated into liposomes for administration in vivo reducing conditions or in response to administration or an exogenous reducing agent.