Old solutions are revealing new possibilities in medicine, offering faster breakthroughs and reshaping the future of healthcare.
Breathing new life into drugs that were once considered unsuccessful is the driving force behind drug repurposing. This innovative approach allows researchers to re-evaluate existing medications or shelved candidates, exploring their potential for new therapeutic uses or targeting overlooked medical conditions. The result? Faster, cost-effective breakthroughs that can transform patient care and reshape the healthcare landscape.
One of the earliest and most notable examples of a repurposed drug is likely sitting in your medicine cabinet. Originally developed in 1899 as a pain reliever and anti-inflammatory agent, aspirin was later found to have potent anti-clotting properties, reducing the risk of heart attacks and strokes. This unexpected discovery transformed aspirin from a simple painkiller into a cornerstone of cardiovascular disease prevention throughout the 20th century.
A more recent example emerged amid the upheaval of the Covid-19 crisis: remdesivir, developed by international pharmaceutical company Gilead Sciences. Initially developed as an antiviral, it became the first drug approved to treat Covid-19, using intravenous infusion to block SARS-CoV-2 replication in the body. The treatment helped patients recover faster and reduced disease progression.
“The research that led to remdesivir began as early as 2009,” says Cathy Su, general manager of Gilead Taiwan. “The potential for remdesivir to have broad spectrum antiviral activity was discovered in research programs analyzing hepatitis C (HCV) and respiratory syncytial virus (RSV). Starting in 2015, remdesivir was further studied in Ebola disease to address the Ebola outbreaks in West Africa.”
The shift in remdesivir’s focus from treating hepatitis to Ebola and later Covid-19 demonstrates how repurposing can address unmet healthcare needs, optimize resource use, and improve patient outcomes by leveraging existing, or even failed, treatments in new ways.
“Since repurposed drugs have already undergone safety and toxicity testing, the time required for development and approval is often shorter than that for new drugs,” says Su. Repurposed drugs like Gilead’s can successfully advance through to preclinical and clinical trials, providing benefits in terms of reduced risks and costs. In Gilead’s case, these properties and the company’s close engagement with regulatory authorities meant that “remdesivir got approved in Taiwan in nine days – the fastest approval in the world,” Su adds.
Unexpected connections
Urgency isn’t solely defined by time pressure – it’s also driven by the multitude of unmet medical needs worldwide, where the real urgency lies in the devastation affecting individuals and the communities supporting them.
Most people will at some point in their lives know someone who is diagnosed with a type of cancer. A small percentage of the population will also find that they are genetically predisposed to multiple forms of cancer. This heightened risk often stems from inherited mutations or syndromes like Lynch and Li-Fraumeni, which significantly increase the likelihood of developing various cancers at a young age.
“At the end of the day, no matter how big or small the incidence for a particular cancer type is, bringing the best innovative medicine to the right patient matters most,” says Vincent Tong, Taiwan managing director of American multinational pharmaceutical Merck Sharp & Dohme (MSD). “These patients can’t wait, and their families and caregivers need help.”
MSD is a leader in immuno-oncology, committed to advancing science, research, and personalized treatments. Tong notes that while the safety of chemotherapy has improved significantly, it remains an invasive treatment, as with any chemical introduced into the body. “You can see it’s killing the cancer cells,” he says. “But at the same time, some of the normal, fast-growing, healthy cells are affected.”
Cancer cells often evade the immune system by expressing proteins that inhibit immune responses. MSD’s anti-PD-1 immunotherapy addresses this challenge by blocking the PD-1 receptor, thereby unmasking cancer cells and enabling the immune system to recognize them as harmful and eliminate them.
“This particular mechanism has enabled us to look into developing treatments targeting different cancers,” says Tong. “So this is not going into new drugs – once we find out a treatment works, this leads us to repurpose and expand engineering to research the application in multiple cancer types.”
Initially approved in 2014 for the treatment of unresectable or metastatic melanoma, MSD’s immunotherapy has since been approved for a broad range of cancers, including non-small cell lung cancer, head and neck squamous cell carcinoma, and urothelial carcinoma. To date, the immunotherapy and its associated research have received approval from the U.S. Food and Drug Administration (USFDA) and the Taiwan FDA for treating 17 different types of cancer.
In 2023, MSD spent more than US$30 billion on clinical research and development at the corporate level. For its part, MSD Taiwan has invested around NT$2.5 billion (nearly US$78 million) on R&D over the past three years, with 100 clinical trials conducted regionally, Tong notes. According to the U.S. National Institutes of Health, drug repurposing has the potential to lower these costs by as much as 60% compared to new drug discovery.
Innovation and creativity are fundamental to successful repurposing. For instance, scientists proved that the cell changes caused by HPV could lead to cervical cancer in women. MSD identified similarities in the pathogenesis of cervical, vulvar, vaginal, anal, oropharyngeal, and other head and neck cancers. These cancers are often linked to how human papillomavirus (HPV) infection affects the cells. This insight influenced the development of HPV vaccines aimed at preventing all HPV-related cancers in both women and men.
Other research has recognized that unmet needs extend not only across all human demographics but also across different species.
A black fly found in Africa can carry a parasitic worm called Onchocerca volvulus, which is responsible for a disease known as onchocerciasis, or “river blindness,” leading to severe itching, skin changes, and, in advanced cases, loss of eyesight. The flies breed near fast-flowing rivers and streams, transmitting the parasite when they bite humans and animals.
“In the 1970s, we developed a drug called Ivermectin to prevent dogs, cows, and horses from being impacted by external parasites,” says Tong. “It’s massive in the animal health business, especially because of its safety. But we also realized that the drug’s application could potentially provide eradication for the parasite causing river blindness in humans.” This hypothesis proved accurate, as the medication destroyed the parasite in patients across Africa, and almost all patients who had lost their eyesight were able to regain it.
Space for growth
Drug repurposing is also proving useful for addressing the growing mental health crisis, fueled by increasing rates of disorders such as major depression and anxiety. In June 2022, the World Health Organization emphasized the urgency of this issue, calling for a transformation in global mental healthcare to meet the rising demand.
Traditional treatment methods, such as selective serotonin uptake inhibitors (SSRIs) and cognitive behavioral therapy, are effective for some patients. However, a significant number do not respond adequately, leaving them vulnerable to severe mental illness and an increased risk of suicide.
“In Taiwan, the regulations surrounding involuntary hospitalization are becoming increasingly stringent,” says Dr. Jou Cheng Ruey, a psychiatrist practicing in Taipei. “Many psychiatric patients may need inpatient treatment but lack the willingness to be hospitalized, making the waiting period for medication very dangerous.”
Even high-risk patients might not meet the criteria for forced hospitalization, notes Jou. To qualify, patients must be diagnosed with a severe mental illness after multiple assessments by medical professionals and deemed a direct and immediate threat to themselves or others. Even then, involuntary commitment can only proceed after evaluations by two independent psychiatrists confirm its necessity.
Jou, a certified specialist in esketamine therapy, says that innovative repurposed treatments offer new hope to patients for whom traditional treatments have proven ineffective. While traditional antidepressants often take weeks to show results, esketamine can deliver a significant antidepressant effect within hours or days.
Esketamine was originally derived from ketamine, whose development history can be traced back to its use as a short-acting anesthetic in medicine, particularly in emergency and surgical settings. It was favored due to its ability to quickly induce anesthesia in patients with minimal respiratory and cardiovascular suppression, making it safe and effective. Over time, ketamine became popular as a recreational drug due to its dissociative effects and hallucinatory properties.
Jou explains that ketamine works by blocking NMDA receptors, leading to increased release of glutamate – the nervous system’s major excitatory neurotransmitter – with receptors throughout the brain and spinal cord. The surge in glutamate promotes neuroplasticity, boosts brain-derived neurotrophic factor expression (vital for long-term memory) and encourages the formation of new synapses – factors believed to underlie its rapid antidepressant effects.
With these findings, scientists have further optimized ketamine’s structure and developed its optical isomer, esketamine. Due to its chemical structure, esketamine has better therapeutic effects than ketamine while reducing dependency and side effects. It is administered in the form of a nasal spray, allowing the drug to quickly reach the brain and take effect, with patients quickly experiencing mood improvements and restored faith that their condition is not out of control.
Naturally, “many challenges arise, with stigma being the biggest issue,” says Jou. The image of the drug as an illegal substance has become deeply ingrained in people’s minds. In Taiwan, the government has made significant strides in drug prevention and education, but this has also heightened public sensitivity toward drug-related substances, he notes.
To address concerns among those refusing to consider this treatment option, detailed discussions with patients and their families about the drug’s mechanism, dosage control, and the necessity of medical supervision help them understand its benefits. The clear evidence gathered through drug repurposing trials provides vital support here, as pre-existing safety testing and USFDA and TFDA approval assist in easing remaining doubts.
Researchers are also looking at psychedelic and other traditionally “recreational” drugs to treat conditions like depression and post-traumatic stress disorder (PTSD). Investigated for PTSD, MDMA-assisted therapy has shown significant symptom reduction in clinical trials. However, the USFDA recently declined approval, citing safety concerns and study biases, necessitating further research.
Other studies are exploring LSD’s potential for generalized anxiety disorder. A Phase 2 trial by New York-based biotechnology company MindMed reported that a single dose led to a 48% remission rate in anxiety symptoms over 12 weeks. MindMed is now in the process of preparing Phase 3 trials to further assess the drug’s efficacy.
MSD’s Tong says harnessing the talent of young people is vital for advancing research and communication around drug innovation and repurposing to educate patients, families, and society. Young minds bring fresh perspectives, adaptability, and creative approaches to scientific exploration. They are also adept at crafting compelling narratives that engage a digital-savvy audience, effectively conveying the importance of repurposed drugs.
For example, Tong says many people in Taiwan – including university students – confuse HIV and HPV due to the single letter difference. “It’s very helpful for people in these target audiences to advise us. I remember in one of our projects, we said to the university students, ‘Tell me how to convince a 20-year-old male who’s a healthy individual to consider receiving an HPV vaccination,’” he says. More attuned commercial insights ensure that information about innovative and repurposed drugs reach the right ears through well-tailored messages.
Young academics play a vital role not only in assessing behavioral trends but also in proposing breakthrough hypotheses. In Taiwan, researchers can submit ideas called Investigator-initiated Study Protocol to companies like MSD, which may sponsor the study after the review process and offer opportunities for these emerging biotech experts and scientific medical researchers to collaborate at clinical sites, says Tong.
The future of drug repurposing is brimming with potential. A strong ecosystem of collaboration among students, industry, and government is positioning Taiwan as a leader in treatment innovation, Tong says.
“If you asked me how I feel about this research, I would say I feel very proud and energized to come back every day,” he says.
