Polymer/drug conjugates that can selectively target and kill cancer cells are described. Conjugates can include a copolymer formed by the reaction of a biocompatible hydrophilic component and a disulfiram derivative. The copolymer reaction product can include additional functional groups pendant to the backbone via a disulfide linkage, for instance copper chelators. The hydrophilic component can form the polymer backbone and/or can form hydrophilic pendant groups off of the backbone. Copper ions can be associated with the copolymer.