of success to finding more cures. Old drugs that were previously withdrawn for

safety reasons may also be re-evaluated as potential candidates for the treatments of

other diseases (Everett 2015). Another great advantage is the innovation of drugs for

orphan diseases—rare diseases that affect only a minute fraction of the population,

therefore not yielding a large enough marketing avenue and, unfortunately, not

gaining the deserving medical resources (Govindaraj et al. 2018). Furthermore,

quicker solutions may be found in response to sudden outbreaks, such as that

observed in the recent COVID-19 global pandemic, to reduce morbidity and mortal-

ity (Serafin et al. 2020). Based on the genetic make-up, patients and diseases can be

stratified into molecular subtypes for better tailoring of personalized medicine with

more specific drugs carrying the least risk (Li and Jones 2012). From today’s

standpoint, we will describe the experimental, in silico, and modern genomic

approaches of DR, as well as its challenges and prospects.

5.2

Experimental and In Silico Approaches to DR

The benefits to DR, such as reduced risk, time, and cost, makes it a widely

favourable approach. For example, in the recent SARS-CoV-2 outbreak, drugs that

were investigated against severe acute respiratory syndrome (SARS) and Middle

East respiratory syndrome (MERS) in the past were being examined against

COVID-19. Drugs that are currently in clinical trials to be repurposed are remdesivir,

danoprevir/ritonavir, interferon β-1b, nitazoxanide, and others (Parvathaneni and

Fig. 5.1 Schematic diagram representing the pipeline of DR, beginning with the identification of a

drug candidate through a disease- or drug-based approach, followed by its analysis and evaluation

and, finally, delivery to the patient

5

Genomic Approaches for Drug Repositioning

51