Repurposing Drugs in Oncology: Current Evidence and Future Traits

Drug repurposing can be defined as exploring, researching, and clinical usage of an old clinically approved drug with known risk factors, usually economical, that can be used as an antineoplastic drug.Such use may reduce the time for new drugs to be incorporated into the treatment armamentarium.Repurposing of a particular drug saves time and money.Thus, repurposing drugs in oncology is the easiest and most economical way to recruit new drugs in the treatment armamentarium of oncology.Many of the drugs, ranging from anti-hypertensives, statins, and antibiotics, have actions on cell proliferation pathways, cytotoxic T cell activation, and protein synthesis.All this knowledge can be utilized in prescribing appropriate drugs so as to potentiate the antineoplastic action.Just to give an example, if a particular patient is having endometrioid adenocarcinoma of the endometrium and is having co-morbid hypertension, then according to published literature, calcium channel blockers acting on voltage-gated calcium channels, like amlodipine, can be repurposed for this purpose.In prescribing amlodipine, the physician is well aware of the side effects and cost-effectiveness of amlodipine.Besides, amlodipine cannot only control the hypertension but can also potentiate the action of the co-medication for endometrioid adenocarcinoma of the endometrium.Likewise, fenofibrate, a fibric acid derivative used as an antilipidemic drug, can be repurposed as an antiangiogenic agent.Many of the drugs conventionally used as antineoplastic agents were actually recruited for some different indication, e.g., Paclitaxel.Paclitaxel was used as a drug to prevent in-stent re-stenosis but was repurposed as an antineoplastic drug.In fact, paclitaxel-eluting stents are used in cardiology, isn't it amazing?Regarding antibiotics, most amazing is the repurposing of azithromycin, a macrolide drug, as a drug to reduce cyclosporine or amlodipine-induced gum hyperplasia.Drugs like levofloxacin, a fluoroquinolone acting on DNA gyrase, can also exhibit antineoplastic action.Ironically, even probiotics can be repurposed to modulate gut immunity, which in turn can help in ameliorating the action of immunotherapy.In a nutshell, repurposing can be the way forward in oncology, especially in an economically developing nation like ours.This perspective gives an insight into the current level of evidence and ignites the reader to take upon this subject to find out new, simpler drugs to be used as antineoplastic drugs, albeit in the presence of conventional chemotherapy agents.