Hydralazine, one of the oldest blood pressure medications in the world, may soon find a second career fighting one of the deadliest forms of brain cancer. Researchers from the University of Pennsylvania, the University of Texas, and the University of Florida published findings in Science Advances in November 2025 showing that this roughly 70-year-old generic drug can force human glioblastoma cells into a dormant, non-dividing state called cellular senescence — essentially putting aggressive tumor cells to sleep. The discovery hinged on finally understanding, after decades of clinical use, exactly how hydralazine works at the molecular level. This matters enormously for the dementia and brain health community.
Glioblastoma is the most aggressive primary brain cancer, with a median survival of just 12 to 15 months even with treatment and a five-year survival rate of only about 6.8 percent. Current therapies are expensive, toxic, and often inaccessible. The prospect of repurposing a cheap, widely available generic drug — one already FDA-approved with decades of safety data — could eventually change the calculus for patients and families who know this diagnosis all too well. This article covers what the Penn-led team actually discovered, how hydralazine’s newly understood mechanism might halt tumor growth, why glioblastoma is so difficult to treat, and what other blood pressure drugs are being repurposed for cancer. We will also address the important limitations of this research and what it means, practically speaking, for patients and caregivers right now.
Table of Contents
- How Is an Old Blood Pressure Drug Being Repurposed as a Cancer Treatment?
- What Hydralazine Does to Glioblastoma Cells — and What It Does Not
- Why Glioblastoma Is So Devastating for Brain Health
- How Drug Repurposing Could Change the Cancer Treatment Landscape
- The Limitations Patients and Caregivers Should Understand
- What the Molecular Discovery Means for Future Brain Research
- Where This Research Goes From Here
- Conclusion
- Frequently Asked Questions
How Is an Old Blood Pressure Drug Being Repurposed as a Cancer Treatment?
First approved by the FDA in the 1950s, hydralazine has been a workhorse medication for treating high blood pressure and remains a first-line treatment for preeclampsia — the dangerous blood pressure spikes that can occur during pregnancy. Doctors have prescribed it for generations, yet no one fully understood what it was doing inside the body at a molecular level. That changed when lead researcher Kyosuke Shishikura, working in the Megan Matthews lab at the University of Pennsylvania, used X-ray crystallography to capture an image of hydralazine physically bound to its target enzyme for the first time. What Shishikura saw was hydralazine latching onto and blocking an enzyme called ADO (2-aminoethanethiol dioxygenase, also known as cysteamine dioxygenase). ADO is an oxygen-sensing enzyme that effectively tells blood vessels when to constrict. When hydralazine blocks ADO, signaling proteins called RGS — regulators of G-protein signaling — remain stable instead of being broken down, which overrides the chemical “squeeze” signal that narrows blood vessels.
That is how it lowers blood pressure. But the researchers realized something else: the same ADO pathway that regulates vascular contraction also helps tumor cells survive in low-oxygen environments. Elevated levels of ADO and its metabolic byproducts had already been linked to more aggressive glioblastoma, but until this study, no one had a good inhibitor to test whether blocking ADO could actually slow the cancer. The comparison to past breakthroughs in drug repurposing is worth noting. Aspirin, originally a pain reliever, eventually proved valuable for cardiovascular protection. Thalidomide, infamous for birth defects, was repurposed for multiple myeloma. Hydralazine’s story follows this same pattern — an old drug, a new understanding, and a potentially transformative application.
What Hydralazine Does to Glioblastoma Cells — and What It Does Not
When the research team treated human glioblastoma brain tumor cells with hydralazine for three days, something striking happened. The cancer cells became enlarged and flattened — a textbook hallmark of cellular senescence. Rather than dividing and spreading, the tumor cells entered what researchers describe as a dormant, non-dividing “sleep mode.” A single dose of hydralazine kept cancer cells locked in this paused state for days, suggesting the effect is durable even without continuous exposure. This is a fundamentally different approach from chemotherapy. Standard chemotherapy drugs attempt to kill cancer cells outright, which often triggers inflammation, damages healthy tissue, and can drive surviving cancer cells to develop resistance. Hydralazine, by contrast, disrupted the oxygen-sensing loop these tumor cells depend on, triggering senescence without the collateral damage typically associated with cytotoxic drugs.
For a cancer as treatment-resistant as glioblastoma, the idea of sidelining tumor cells rather than trying to obliterate them represents a genuinely novel strategy. However, there is a critical caveat that patients and families need to understand clearly: these findings are preclinical. The experiments were conducted on human glioblastoma cells in a laboratory, not in living patients. Drugs that show promise in cell cultures fail in human trials far more often than they succeed. Senescence itself is a double-edged sword in cancer biology — senescent cells can sometimes reawaken or secrete inflammatory signals that affect surrounding tissue. The researchers have opened a promising door, but clinical trials in actual glioblastoma patients have not yet begun, and this discovery will not immediately change treatment protocols.
Why Glioblastoma Is So Devastating for Brain Health
Glioblastoma occupies a uniquely grim place in oncology. With a median survival of approximately 12 to 15 months under treatment — and roughly four months without any treatment — it is among the most lethal diagnoses a person can receive. The five-year survival rate hovers around just 6.8 percent. For families already navigating the complexities of brain health, cognitive decline, or dementia care, a glioblastoma diagnosis can feel like a catastrophic escalation with almost no good options. The standard treatment involves surgery to remove as much of the tumor as possible, followed by radiation and the chemotherapy drug temozolomide. Even with this aggressive protocol, glioblastoma almost always recurs.
The tumor is deeply infiltrative, threading its tendrils into healthy brain tissue in ways that make complete surgical removal virtually impossible. The blood-brain barrier complicates drug delivery, and the tumor’s genetic heterogeneity means it can rapidly evolve resistance to whatever is thrown at it. Current therapies are also expensive and physically punishing, which makes access a serious equity issue, particularly for older patients or those in lower-resource settings. This is precisely why the hydralazine finding is generating attention. The drug costs pennies per dose, is manufactured generically around the world, and has a well-documented safety profile spanning seven decades. If clinical trials eventually confirm that it can slow glioblastoma progression in patients — even modestly — it would represent the kind of accessible, low-toxicity option that the field desperately lacks.
How Drug Repurposing Could Change the Cancer Treatment Landscape
Hydralazine is not the only blood pressure medication attracting interest from oncology researchers. Losartan, an angiotensin receptor blocker commonly prescribed for hypertension, has shown promise in pancreatic cancer. A Phase II clinical trial led by researchers at Harvard and Massachusetts General Hospital combined losartan with FOLFIRINOX chemotherapy in patients with locally advanced pancreatic cancer and demonstrated meaningful effectiveness. Pancreatic cancer, like glioblastoma, is notoriously resistant to treatment, so the results drew significant attention. Meanwhile, propranolol — one of the best-known beta-blockers — received Orphan Drug Designation from the European Commission for treating soft tissue sarcoma and has advanced beyond preclinical research into Phase II and Phase III readouts as of early 2026. The common thread in all these cases is that researchers are exploiting biological mechanisms that overlap between cardiovascular regulation and tumor biology.
Blood vessels and tumors both respond to oxygen levels, growth signals, and stress pathways. A drug designed to modulate one system can sometimes disrupt the other. The tradeoff with drug repurposing is speed versus specificity. A repurposed drug can reach patients years faster than a novel compound because the safety data already exists and the manufacturing infrastructure is already in place. But these drugs were not designed for cancer, so their anticancer effects may be weaker or less targeted than purpose-built therapies. The ideal scenario for hydralazine might not be as a standalone treatment but as part of a combination regimen — used alongside surgery, radiation, or other drugs to exploit its unique mechanism without relying on it alone.
The Limitations Patients and Caregivers Should Understand
It is tempting, especially when facing a devastating diagnosis, to read about preclinical research like this and want to act on it immediately. Some patients or families may wonder whether they should ask their doctors to prescribe hydralazine off-label for glioblastoma right now. This is understandable but premature. The gap between forcing cancer cells into senescence in a dish and achieving the same effect inside a living human brain — past the blood-brain barrier, in the complex tumor microenvironment, alongside all the body’s other systems — is enormous. There are also open questions about senescence as a therapeutic strategy.
While putting cancer cells to sleep sounds appealing, senescent cells are not dead cells. They remain in the body, and research in aging biology has shown that accumulated senescent cells can contribute to chronic inflammation and tissue dysfunction over time. Whether hydralazine-induced senescence in a tumor would remain stable, or whether those dormant cells might eventually reawaken or cause secondary problems, is simply unknown at this point. Patients currently being treated for glioblastoma should continue following their oncology team’s recommendations. Anyone interested in hydralazine’s potential role should watch for upcoming clinical trials — ClinicalTrials.gov is the best resource for tracking when and where human studies begin. Discussing emerging research with a neuro-oncologist is always reasonable, but self-prescribing or pressuring a doctor to prescribe based on preclinical data alone carries real risk and no proven benefit.
What the Molecular Discovery Means for Future Brain Research
Beyond cancer, the revelation that hydralazine works by blocking the ADO enzyme opens new questions about oxygen sensing in the brain more broadly. ADO’s role in detecting and responding to low-oxygen conditions is relevant not only to tumors but to stroke, vascular dementia, and other conditions where the brain’s oxygen supply is compromised.
Understanding how this enzyme pathway functions — and how to modulate it — could eventually inform research into neuroprotection and cerebrovascular disease. For instance, if blocking ADO stabilizes RGS proteins in ways that alter vascular signaling, researchers may want to investigate whether long-term hydralazine use in blood pressure patients has had any unrecognized effects on brain health outcomes. Decades of prescription data exist, and retrospective epidemiological studies could mine that data to look for correlations between hydralazine use and rates of stroke, cognitive decline, or even brain cancer incidence.
Where This Research Goes From Here
The Penn-led team’s work establishes a clear molecular target — ADO — and a candidate drug with an established safety record. The next logical step is designing clinical trials that test hydralazine in glioblastoma patients, likely beginning with studies that combine it with standard-of-care therapy rather than replacing existing treatment. Given that hydralazine is already approved and inexpensive, the regulatory pathway for such trials would be substantially shorter than for an entirely new compound.
Looking further ahead, the broader principle at work here — that old drugs harbor undiscovered mechanisms with relevance to diseases far beyond their original indication — suggests that the pharmacopoeia we already have may contain more surprises. For patients and caregivers in the brain health community, this is a reason for cautious, clear-eyed hope. Not hope that a single pill will cure glioblastoma tomorrow, but hope that the science is advancing, that the tools are becoming sharper, and that sometimes the next breakthrough has been sitting in the medicine cabinet all along.
Conclusion
Hydralazine’s journey from a 1950s blood pressure pill to a potential glioblastoma therapy illustrates the power of understanding old drugs through new science. The University of Pennsylvania team’s discovery that hydralazine blocks the ADO enzyme — disrupting the oxygen-sensing pathway that aggressive brain tumors exploit to survive — provides both a molecular explanation for how the drug has worked for decades and a compelling reason to test it against one of the deadliest cancers known. Combined with parallel repurposing efforts involving losartan for pancreatic cancer and propranolol for soft tissue sarcoma, the field of cardiovascular-to-oncology drug repurposing is gaining real momentum.
For families and caregivers navigating brain health challenges, the practical takeaway is measured. This research is promising but preclinical, and it will not change glioblastoma treatment protocols today. What it does is add a credible new avenue to a field that desperately needs options — particularly affordable, accessible ones. Watch for clinical trial announcements, maintain open conversations with your medical team, and take heart that researchers are looking at this problem from every conceivable angle, including the pharmacy shelf that has been right in front of us for 70 years.
Frequently Asked Questions
Can I ask my doctor to prescribe hydralazine for glioblastoma right now?
Not advisably. The cancer-related findings are preclinical, meaning they have only been demonstrated in laboratory cell cultures, not in human patients. Hydralazine is FDA-approved for blood pressure, but prescribing it off-label for brain cancer without clinical trial evidence would carry unknown risks and no proven oncology benefit. Discuss the research with your neuro-oncologist, but do not self-prescribe.
How does hydralazine differ from standard chemotherapy for brain cancer?
Standard chemotherapy drugs like temozolomide attempt to kill cancer cells directly, which can trigger inflammation, damage healthy tissue, and lead to drug resistance. Hydralazine, in lab studies, pushed glioblastoma cells into cellular senescence — a dormant, non-dividing state — without the toxic side effects associated with cytotoxic drugs. However, this has only been shown in cell cultures so far.
What is cellular senescence, and is it the same as killing cancer cells?
No. Cellular senescence is a state where cells stop dividing but remain alive. Think of it as a deep pause rather than cell death. While this halts tumor growth, senescent cells remain in the body, and long-term consequences of tumor cell senescence in living patients are not yet fully understood.
Is hydralazine safe for long-term use?
Hydralazine has over 70 years of safety data as a blood pressure medication. Common side effects include headache, rapid heartbeat, and joint pain. At higher doses, it can rarely cause a lupus-like syndrome. Its long-term safety for blood pressure management is well documented, but its safety profile in the context of cancer treatment has not been studied in clinical trials.
Are other blood pressure drugs being tested against cancer?
Yes. Losartan has shown promise in a Phase II clinical trial for locally advanced pancreatic cancer in combination with chemotherapy. Propranolol has received Orphan Drug Designation in Europe for soft tissue sarcoma and has progressed into Phase II and III trials as of early 2026.
When might clinical trials for hydralazine in glioblastoma begin?
No specific timeline has been announced. The preclinical findings were published in November 2025 in Science Advances, and the next step would be designing and funding human trials. Patients can monitor ClinicalTrials.gov for announcements about new glioblastoma studies involving hydralazine.
