To maintain a high local concentration of chemotherapy, Byrne et al. have created two devices, implantable and transdermal, that rely on iontophoresis (the flow of charged molecules in an electric field). The devices improved the delivery and efficacy of gemcitabine in an orthotopic patient-derived xenograft mouse model of pancreatic cancer, as well as of cisplatin in two aggressive orthotopic mouse models of breast cancer, increasing both tumour growth inhibition and overall survival. The devices also showed favourable pharmacokinetic profiles, maintaining high local drug concentrations and low systemic exposure.