Repurposing drugs to treat dangerous diseases

In drug repurposing new uses are identified for a drug outside of its original scope of indication. This translates into quicker and more effective treatment delivery for patients.

DIDI MMATLADI

Imagine going to the doctor to get medical help and you’re told, “Sorry, there is too little known about your condition, I cannot treat you for it now, but hopefully, there will be a drug developed for it soon.”

If the doctor does not know what to do, who does? And how soon could a drug developed for your condition be available? The process of developing drugs is extensive and rigorous. It takes on average 10 years from the ‘initial discovery’ of drugs, to their approval for use and ultimate availability through prescription or over the counter.

NEW SOLUTIONS FROM KNOWN DRUGS

There is an urgent need for more efficient and solutions-driven systems to identify alternate treatments when existing drugs are not available. Drug repurposing (or repositioning) is a costefficient approach that eliminates the lengthy timeframes of conventional drug development, thus giving patients treatment sooner.

Professor Yahya Choonara, Director and Principal Researcher at the Wits Advanced Drug Delivery Platform (WADDP) research unit, defines drug repurposing as the process through which new uses for a drug are identified outside that drug’s original scope of indication (or the re-profiling of drug molecules).

“This approach is increasingly explored by drug discovery research teams as it provides benefits over conventional ways of searching for a new ‘active pharmaceutical ingredient’,” says Choonara. “Drug repurposing may reduce the risks that are associated with the process of conventional drug discovery and development, as existing knowledge on candidate drugs can be further developed more quickly and enhanced.”

Repurposing of drugs means that drug developers employ ‘de-risked compounds’, which makes the ‘re-purposable’ drug candidate easier to develop further. Because the re-purposable drug has already gone through multiple rigorous regulatory stages for approval, drug repurposing scientists can adopt more systematic processes to identify alternative prospects for its use. This alone fast-tracks the gap between identifying drugs with desirable effects, and getting them on the shelves in pharmacies.

DECADES AND DOLLARS INHIBIT DRUG DELIVERY

Researching and developing new drugs is expensive. Pharmaceutical companies risk financial losses if their drug discovery and development programmes fail, or the drugs require further development to secure the necessary approvals. It is the end-customer who will likely have to pay higher prices for these drugs.

Despite extensive advancements in scientific medical technologies and highly mechanised manufacturing capabilities, research suggests that the cost of developing new drugs is still high at an estimated average cost of $1.3 billion in 2020.

Repurposed drugs accounted for 43% of drugs approved by the US Food and Drug Administration in the first quarter of 2020, studies found. This form of drug development has seen the

“Drug repurposing may reduce the risks that are associated with the process of conventional drug discovery and development”

pharmaceutical industry’s annual revenue grow by an estimated 25-40% (2020), showing that it can become a feasible and standard consideration in the drug development process.

Diseases are growing globally, highlighting the urgent need for pharmaceutical research innovation that will help meet the demand for ‘new’ and effective drugs, while balancing this with the pharmaceutical industry’s ability to produce these efficiently and timeously.

DISRUPTING CANCER DRUG RESISTANCE

There is a great need to explore drug repurposing in treating patients with cancer in South Africa, says Dr Ekene Emmanuel Nweke, Associate Researcher in the Wits Department of Surgery, who recently contributed a book chapter, Drug sensitivity and drug repurposing platform for cancer precision medicine. Increasingly, cancer patients are developing drug resistance to dedicated cancer medications already on the market. Although some developed countries have seen improved five-year survival rates in most cancers, mainly because of early detection and advanced treatment options, certain cancers such as pancreatic cancer are still problematic to treat due to their highly resistant nature.

“The whole point of trying to develop cancer precision medicine is to ensure that we have tailored treatments for patients. Drug resistance in patients is a huge issue when it comes to cancer treatment. By repurposing drugs and screening these drugs specifically to the patient’s needs, we hope to avoid resistance and improve the patient’s outcome,” says Nweke.

Choonara stresses that the efficiency of drug repurposing requires a combination of access to molecular data, appropriate bio-analytical expertise to enable robust insights, and expertise and experimental set-up for pharmaceutical formulation, validation and clinical development.

Finding the right combinations of ‘de-risked compounds’ to repurpose drugs for multiple diseases requires both scientific and clinical collaboration, a multidisciplinary approach often adopted by the Faculty of Health Sciences at Wits.

“Drug repurposing can strengthen healthcare systems by making available a wider variety of therapeutic interventions and promotes a multidisciplinary effort among healthcare professions to get such pharmaceutical products to the market,” says Choonara. C