A Review on Exploring the Opportunities of Polymer Drug Conjugated Systems for Targeted Cancer Treatment

Polymeric drug conjugates (PDCs) for cancer therapy have been a hot research topic for the past three decades. Successful examples of PDC conjugates have demonstrated sustained drug release action with decreased systemic toxicity and enhanced tumor retention effect (EPR) via active as well as passive targeting mechanisms. Therefore, the PDC approach has now become a keystone of the drug delivery system for cancer and other diseases. In recent years, several PDCs have successfully made up to the clinical trials. The approach aids targeted delivery of the anticancer drugs to the tumor site without disturbing the healthy cells. The selection of the over-expressed receptor and the receptor-ligand plays a vital role in designing the receptor-targeting PDC so that it is able to distinguish between the healthy cell and the tumor cell. Continuous efforts are being made in research and development toward an active targeted PDC delivery system to revolutionize cancer treatment despite the controversy built due to heterogeneity in tumor models. This review highlights the chemistry aspects involved in the preparation of PDCs that deal with novel molecular tumor targets and strategies used for the development of targeted PDCs for delivering the drug payload via active or passive targeting. Furthermore, it sheds light on the challenges faced by targeted PDCs as novel drug delivery systems.