Repurposing existing drugs for new indications

What is drug repurposing

Drug repurposing is the process of finding new uses for existing drugs. This is often done by generating scientific evidence about the effect of the drug in a condition that it is not licenced to treat.

Drug repurposing goes by many names: drug repositioning, drug reprofiling and drug rescue. Call it what you will, but the following remains true: it is the process of identifying a new use for an old drug.

Why does repurposing matter?

The development of completely new drugs, often called new chemical entities, is an expensive and time-consuming process. New chemicals have to be tested extensively to ensure that they are safe for human use.

How the drug reacts in the body must be known and understood. Extensive testing has already been done for existing drugs, which means that if we can find new uses for them, it would save both time and money in the drug development process.

Why does repurposing matter for rare diseases?

Advancing rare disease research is no easy feat. Developing treatments that patients can access is even more challenging. The high cost of drug development, limited understanding of rare diseases and small patient populations make the development of rare disease treatments less appealing for companies. These challenges are often overcome by companies charging high prices for rare disease treatments, which are otherwise known as orphan drugs.

Unfortunately, these high prices can often prevent the very patients who need the drugs from receiving them; either due to a lack of provision on their national health service or the high personal cost of health insurance or drug purchases.

Drug repurposing helps to overcome some of these challenges as it:

  • Reduces the time needed to test the effect of drugs in people. 
  • Reduces the cost involved in getting a drug ready to test in people.
  • Reduces some of the knowledge gap present when running a clinical trial – knowing more about the drug helps to speed the process, especially when you may have relatively little knowledge about the rare disease.

Treatments that do exist often cost seven times the price of those developed for a common condition

This means that drug repurposing has the potential to develop orphan drugs more quickly and at less expense. This could lower drug prices.

More importantly, the lower barrier to beginning repurposing research means that academic researchers can lead rare disease trials for repurposed drugs and patient groups and charities can more easily fund the required research.

Is repurposing drugs common?

Repurposing is increasingly common. There is more research into different uses for common drugs happening than in previous years. There are also more drugs licenced for secondary uses. However, there are still a lot of obstacles to repurposing that are mostly connected to the patent system.

Making a new drug is a tremendously expensive process. The drug development process needs to be tightly regulated to ensure that new products are not harming those who are taking them. To compensate for this, companies that create a new drug secure a patent. A patent lasts for a certain period of time, and while it lasts only that company can make and sell the drug. Patents, along with a number of drug licencing laws, ensure that companies can make enough money from a new drug to compensate for the cost of developing it. After a set period of time, a drug is said to become “generic”. This means that other companies can make the drug, which results in the market becoming competitive and prices going down.

When repurposing a drug, companies typically feel that it is hard to secure a patent (or other protections) that can ensure that the money invested in drug testing is recovered. This makes repurposing old generic drugs risky and unappealing to companies, making it harder to get a generic drug available on the market for a new condition. It is a serious barrier to widespread drug repurposing.

Can drugs treat more than one condition?

Yes, most drugs can. Drugs are chemicals that modify the biochemical pathways in our cells. It is rare that a drug will only affect a single pathway, in a single way, with a single effect. This is why most drugs have side effects. In drug repurposing, we use the side effects of a drug to treat a different condition.

What are some successful examples of repurposing? 

Nitisinone for alkaptonuria

After a failed trial in USA, the Alkaptonuria Society based in the UK decided to drive research in the field of AKU with the hope of running a more complete trial for the drug nitisinone. The patient group raised funding to conduct the first autopsy of a person affected by AKU, developed a new metric to measure disease severity and created a new mouse model of the disease.

This all led to the formation of an international consortium, including the patient group, which secured €6 million funding to run a phase II and phase III study of nitisinone in AKU.

The results were overwhelmingly positive. The drug is now the first licenced treatment for alkaptonuria after previously being used in tyrosinemia type 1 and as a weed killer!

Everolimus for tuberous sclerosis

In 1977, when the Tuberous Sclerosis Association (TSA) first formed, the charity strived to raise £30,000 for research into the mechanism behind tuberous sclerosis. The research showed hyperactivity of the mTOR pathway. Academics hypothesised that mTOR inhibitors might be an effective treatment for tuberous sclerosis.

A small patient group and government-funded trial was conducted to test their hypothesis. The trial yielded positive results, which led to a pharmaceutical company funding a larger, international phase III study. This tested whether their patented drug, Everolimus, would treat tuberous sclerosis. The clinical trial results were positive and Everolimus gained regulatory approval for SEGA (a type of brain tumour) and epilepsy associated with tuberous sclerosis.

Sirolimus for ALPS

Sirolimus was successfully repurposed to treat the rare disease, autoimmune lymphoproliferative syndrome (ALPS), after originally being used as a generic transplant drug.

In 2004, US charity Cures Within Reach funded a single researcher to conduct a study using repurposed drugs in an ALPS mouse model. The ALPS mouse model saw a positive impact when sirolimus was added. Cures Within Reach provided further support for a pilot study with six ALPS patients. After 90 days of the study, five of the six patients were in complete remission. The results of the pilot study were published in an open-access journal to promote the use of off-label drugs.

Cures Within Reach estimates that the use of sirolimus saves $50,000 per patient per year.

Why does Beacon care about drug repurposing? 

At Beacon, we don’t believe that the traditional model of drug development is able to meet the huge unmet need of the global rare disease community. We need new routes to develop more treatments, more quickly and more cheaply.

Drug repurposing research is accessible to patient organisations and academics. It lends itself to new modern AI approaches that can identify repurposing opportunities.

We want to raise awareness about drug repurposing’s potential to help develop treatments for those who are in desperate need. We want to find ways to smooth the pathway to develop repurposed drugs and make them accessible to patients.

Photo of a woman holding a sign which reads I support drug repurposing because it could bring meaningful therapies faster to those for which time is of the essence

Want to learn more?

Subscribe to our Community Mailing List to be amoung the first to hear about our next Drug Repurposing for Rare Diseases Conference. 

Learn more about our role in REMEDi4ALL, a new flagship EU-funded initiative driving medicines repurposing across the UK and Europe.

Visit our MCDS-Therapy page to learn more about our role in this international partnership, which is repurposing a generic epilepsy drug to treat the ultra-rare bone disease, metaphyseal chondrodysplasia type schmid (MCDS). 

Visit our Social Impact Bond page to learn more about our historical work developing a new funding model to drive generic drug repurposing for rare diseases. 

Visit The Resources Hub for an introductory course on drug repurposing for rare disease patient groups.

Read about drug repurposing in the book Rare Diseases – Challenges and Opportunities for Social Entrepreneurs, edited by our co-founder Nick Sireau. Visit our publications page to learn more.