**5. Future perspectives**

Given that the *de novo* drug discovery approach for epigenetic targets is timeconsuming, costly, and has a high failure rate in clinical trials, researchers may consider increasing their efforts into repurposing drugs with known epigenetic effects for newer disease indications. One of the merits of drug repurposing is that it alleviate patients' treatment costs and provide hope to those with rare conditions. Recognizing this approach as a great benefit to patients, governmental agencies and philanthropic organizations should increase the establishment of funding programs for drug repurposing endeavors [109]. More importantly, the paradigm for drug discovery is moving from a single target to a multitarget approach and drug repurposing is a suitable strategy to meet this evolving paradigm in pharmacology [110]. Thus, considering the slow pace and millions to billions of dollars spent on bringing a single drug to market, it is worthwhile to steer efforts and resources towards drug repurposing for epigenetic-based therapy in human diseases.
