Repurposing or “repositioning” existing therapies for alternative disease indications, based on similarities in pathophysiology or molecular pathways, or by chance, is attractive as an approach, saving significant drug development costs and time, with side-effect profiles known and existing data required for approval by licensing bodies such as the Food and Drug Administration (FDA) or the European Medicines Agency (EMA). Examples of repurposed drugs include sildenafil (Viagra), a phosphodiesterase inhibitor developed initially to treat angina and now used to treat erectile dysfunction, and metformin, currently studied in numerous Phase II and Phase III clinical trials as a cancer therapeutic [ ].