Drug Repurposing for Rare Diseases

14th August 2025

By Mia Turner, Scientific Communications & PR Intern

A rare disease is classified as one that affects less than 1 in 2,000 people [1]. As such, research in rare diseases isn’t as attractive to pharmaceutical companies, since the treatments are aimed at such a small group of patients and so the opportunity to recover development costs and financial benefit is limited.

The field of drug repurposing offers hope, emerging as a leading way to provide treatments and potential cures for patients with these rare diseases. Drug repurposing for rare diseases is a continually developing field in which there are new indications for existing drugs to be found, providing hope to patients with diseases that were previously untreatable. While researching this topic, I was particularly interested in the ways that this field is constantly developing, and evolving in different directions with scientists finding new ways to collaborate on existing ideas to produce the best patient outcomes possible…

In this article, we’ll cover what drug repurposing is and why it’s crucial to rare disease research, as well as some more specific examples of where drug repurposing has been successful through collaborative efforts.

What is drug repurposing?

As described by Frontiers in Medicine, drug repurposing is ‘developing an existing drug outside the scope of its original indication, with the ultimate purpose of obtaining a new regulatory-approved indication that leads to enhanced patient access opportunities, better prescribing information and better treatment guidance’ [2]. It has many uses across different areas of scientific research, one of which is in specifically repurposing drugs for rare diseases.

Several drugs have been successfully repurposed, perhaps the most dramatic of which was the resurgence of thalidomide and its gaining of FDA approval in 2006 to treat plasma cell myeloma. After being marketed originally as a sedative in 1950, it then became immensely popular with pregnant women for its anti-emetic effects – before causing controversy when reports of it causing birth defects began to circulate, resulting in its eventual removal from the market in 1961. Once its mechanisms of action were further researched and understood thalidomide gained attention once more as an important drug in the treatment of various inflammatory and malignant diseases [3].

Other drugs that have been repurposed include an acne medicine which has found use as part of a treatment course for leukaemia, and propranolol, which will be focused on later [4].

Methods for drug repurposing

There have been several advances made in drug repurposing methods over recent years. Disease models can be built for pathway analysis, giving a deeper understanding of the underlying mechanisms that can be matched to repurposed drugs. Beyond this, knowledge graphs and graph neural networks can be used to collate more information. This can then be used in association with compound libraries through automated literature and text mining to find the most applicable and accurate data, quickly and efficiently [5].

It’s here that Artificial Intelligence (AI) begins to play an instrumental role as, using high-throughput screening, ‘researchers can power systematic and large-scale drug repurposing research, by matching biological assays to compounds with the required biological activity’. This automated process is highly beneficial in drug repurposing because there are such high volumes of data pertaining to research on drugs that can be approved for alternative use, whether they originally failed or were successful, which is key for finding new treatments [5].

Why target rare diseases?

There are such limited alternate options for patients with rare diseases because the patient populations are small, the diseases are complex and there is a severe lack of understanding of disease pathobiology [2].

As a result, only 5% of the 6,000-8,000 rare diseases have any regulatory-approved course of treatment or cure, making drug repurposing critical to the development of treatments for rare diseases [2]. This approach enables scientists to redirect previous proven efforts to a new target, taking far less time to produce results and ensuring that efforts of producing a new drug from scratch will not be wasted.

Previous elements such as drug properties, safety profiles, mechanisms of action and interactions with biological systems are already known and able to be considered when repurposing drugs – which can provide serious acceleration to the process of finding new treatments for rare diseases. De novo drug design typically takes 10-15 years and can cost up to £2 billion, as opposed to drug repurposing which can cut at least 3 years off the development pathway and cut development costs by at least 75%. Coupled with the substantially higher success rate of repurposed drugs compared to de novo drugs, there is a strong argument for drug repurposing to target rare diseases [5].

Collaboration in Drug Repurposing

Whilst AI has been shown to make significant progress in the drug repurposing field, the idea of bringing together experts from different fields in an effort to repurpose drugs for rare diseases has also shown success and highlighted new research findings through the sharing of insights and collaborative efforts. Conventions and events that are hosted by scientists in the drug repurposing field provide exciting opportunities for their peers to collaborate and find innovative new applications for treatments, much faster than usual.

Such collaboration has been recently seen at the International Drug Repurposing Conference, held earlier this year. Of note, collaborative efforts at events such as this enable the de-duplication of research through sharing of clinical trial results, harnessing of AI drug screening and multi-national collaboration that ‘bridges the gap between researchers, regulators and pharmaceutical industries’ [6].

In addition to this, events held in recent years bringing together large groups of rare disease scientists and those specifically invested in the repurposing of drugs have yielded many positive results; nearly 100 healthcare professionals and researchers from 28 countries were brought together for 48 hours in a world-first ‘Undiagnosed Hackathon’ and managed to use their collaborative data to find new treatment lines for 10 families with undiagnosed rare diseases, using repurposed drugs [7].

In the Spotlight: The Repurposing of Propranolol for Rare Diseases

Collaboration between private and public groups also offers hope. Bordeaux University in collaboration with a private company, Pierre Fabre laboratories, worked exhaustively to study the effects of propranolol in infants with haemangiomas [2].

In 2008, the so-called ‘off label’ effects of propranolol were first seen in benign tumour infantile haemangioma. It was originally shown to have a profound impact on 11 cases of benign infantile haemangioma, a benign vascular tumour presents in 4-5% of neonates and affects the face and limbs. Pierre Fabre laboratories obtained a license from the university to fund a study which ultimately enabled propranolol to become a licensed medication indicated in the treatment of infantile haemangiomas [8].

Whilst propranolol is typically prescribed for high blood pressure, irregular heart rate and anxiety, it has also shown positive effects as an antiangiogenic, pro-apoptotic, vasoconstrictor and anti-inflammatory drug. The progress that has been made in the repurposing of propranolol has also become more widely spread with new applications in the treatment of other rare diseases such as Lafora disease, soft tissue sarcoma and Hereditary Haemorrhagic Telangiectasia (HHT), illustrating how advancements for a single treatment can have vast effects on the community of patients affected by rare diseases [8].

Summary

The process of drug repurposing enables acceleration of development. Coupling this process with collaborative approaches at conferences, events, partnerships etc. offers additional benefits in terms of advocation for patients and exploration of new approaches, and ultimately encourages entrepreneurship too.

Through the vital research carried out by those focused on rare diseases specifically, thousands of patients around the world that suffer from some of the most niche and debilitating diseases can access new treatments and potential cures.

With the collaborative efforts of the scientific community and use of newer technologies such as AI, the limits on what can be achieved are constantly being pushed aside to make way for new progress and developments, giving hope to many and providing new insight for all.

References

[1] Beacon. (n.d.). What are rare diseases? | Genetic disorders. [online] Available at: https://www.rarebeacon.org/rare-diseases/what-are-rare-diseases/.

[2] Anneliene Hechtelt Jonker, O’Connor, D., Cavaller-Bellaubi, M., Fetro, C., Gogou, M., Peter, Martin de Kort, Stone, H., Valentine, N. and Maria, A. (2024). Drug repurposing for rare: progress and opportunities for the rare disease community. Frontiers in Medicine, 11. doi:https://doi.org/10.3389/fmed.2024.1352803.

[3] Rehman, W., Arfons, L.M. and Lazarus, H.M. (2011). The rise, fall and subsequent triumph of thalidomide: lessons learned in drug development. Therapeutic Advances in Hematology, [online] 2(5), pp.291–308. doi:https://doi.org/10.1177/2040620711413165.

[4] The Economist. (2019). ‘Repurposing’ off-patent drugs offers big hopes of new treatments. [online] Available at: https://www.economist.com/international/2019/02/28/repurposing-off-patent-drugs-offers-big-hopes-of-new-treatments.

[5] www.elsevier.com. (2021). Elsevier. [online] Available at: https://www.elsevier.com/en-gb/industry/drug-repurposing#3-drug-repurposing-methods [Accessed 12 Aug. 2025].

[6] Parr-Reid, S. (2025). Reflections from the International Drug Repurposing Conference 2025 – Ataxia UK. [online] Ataxia UK – Supporting people with ataxia until a treatment or cure is found. Available at: https://www.ataxia.org.uk/research-news/reflections-from-the-international-drug-repurposing-conference-2025/.

[7] Delgado-Vega, A.M., Cederroth, H., Taylan, F., Ekholm, K., Ek, M., Håkan Thonberg, Anders Jemt, Nilsson, D., Jesper Eisfeldt, Saether, K.B., Höijer, I., Ozlem Akgun-Dogan, Asano, Y., Barakat, T.S., Dominyka Batkovskyte, Gareth Baynam, Bodamer, O., Wanna Chetruengchai, Corcoran, P. and Couse, M. (2024). Pushing the boundaries of rare disease diagnostics with the help of the first Undiagnosed Hackathon. Nature Genetics, [online] 56(11), pp.2287–2294. doi:https://doi.org/10.1038/s41588-024-01941-1.

[8] Cuesta, A.M., Gallardo-Vara, E., Casado-Vela, J., Recio-Poveda, L., Botella, L.-M. and Albiñana, V. (2022). The Role of Propranolol as a Repurposed Drug in Rare Vascular Diseases. International Journal of Molecular Sciences, 23(8), p.4217. doi:https://doi.org/10.3390/ijms23084217.