Increasing opportunities of drug repurposing for treating breast cancer by the integration of molecular, histological, and systemic approaches

Abstract Drug repurposing is a strategy of using approved or investigational drugs for a different purpose other than their original medical use. There is a growing interest in the study of commonly used drugs for the treatment of various malignancies. The advantages of known, well-tolerated adverse effects and safety profiles of these commonly used drugs have made their use in cancer treatment more appealing than many common chemotherapeutic agents that have a wide range of toxicities. In this chapter, we have reviewed studies involving metformin, disulfiram, propranolol, antiviral, antipsychotics, thalidomide, artemisinin, mebendazole, and flunarizine for the treatment of breast cancer. The mechanisms of action of original uses of these drugs are first reviewed, followed by revealing their new mechanisms of action for the antibreast cancer effects both in preclinical and clinical settings. The drug effects concerning histological and systemic approaches are also reviewed. In the end, future perspectives of drug repurposing for breast cancer treatment are discussed. The use of these repurposed drugs for breast cancer therapy has shown great promise, which will help establish a better treatment regime for breast cancer patients.