New Drug Delivery Strategies Targeting the GnRH Receptor in Breast and Other Cancers

Cancer is the uncontrolled division of abnormal cells in a specific organ. Globally, about one in six deaths is due to cancer. Despite the plethora of research being undertaken worldwide to find a cure for cancer, it remains a significant challenge. Cancer targeting via agents designed to interfere with some specifically or highly expressed molecules in cancer cells has been a shift in the treatment of various forms of cancers. The development of drug delivery systems, specifically to cancer cells, is a common approach that succeeded in increasing the efficacy and reducing the side effects of different anticancer agents. Gonadotropin-releasing hormone (GnRH) is a naturally occurring hormone with receptors overexpressed in many types of cancers related or unrelated to the reproductive system. Several drug delivery systems were developed using GnRH derivatives as targeting agents. In this review, we first discuss the role of GnRH and its receptors in cancer. Then, we provide a detailed insight into different delivery systems developed using GnRH derivatives as targeting agents in various types of GnRH receptor overexpressing cancers. Some promising findings from these studies indicate that GnRH receptor targeting is a potential strategy to efficiently guide anticancer therapeutics, diagnostic agents, and nucleic acids directly to cancer cells. Lastly, some limitations of the current research and suggestions for more successful outcomes in clinical trials of these delivery systems are highlighted.