Recent progress in polymer-based platinum drug delivery systems

Platinum drugs comprise of almost 50% of all currently used anticancer drugs. They are now widely used in the clinical therapy of various solid tumors, including ovarian, head and neck, colorectal, lung cancers, and so forth. However, their extensive systemic toxicity and the drug resistance acquired by cancer cells limit the applications of platinum drugs. Modern nanobiotechnology provides the possibility for targeted delivery of platinum drugs to the tumor site, thereby minimizing toxicity and optimizing the efficacies of the drugs. Numerous drug delivery carriers, such as polymer nanoparticles, solid lipids, and inorganic nanoparticles, have been developed over the years for delivering platinum drugs. Thus, significant improvements have been made in this field, especially for polymer-based platinum drug delivery systems. In the past five years, particularly interesting studies have been done regarding polymer-based carriers for platinum(IV) drugs, which are chemically inert but can be activated either by intracellular glutathione (GSH) and ascorbic acid (chemically reductive platinum(1V) drugs) or by ultraviolet (UV)/green light (photosensitive platinum(IV) drugs). This review presents a comprehensive overview on the development of various types of polymer-based platinum drug delivery systems. It spans both single-drug carriers and carriers that are combined with other imaging agents, drug sensitizers, and anticancer drugs. Their fabrication methods, mechanisms of action, their applications in cancer therapy, as well as the prospect of their development in the future are also predicted. (C) 2018 Elsevier B.V. All rights reserved.