Cheap blood pressure drug shows promise against deadly brain cancer in early study

Researchers at the University of Pennsylvania have identified an unexpected connection: a blood pressure medication that costs thirty-three cents per pill may slow the growth of glioblastoma, one of the most lethal cancers known to medicine. The drug is hydralazine, sold under the brand name Apresoline, and it has been in use for seven decades. About six million Americans currently take it to manage high blood pressure by relaxing blood vessel walls.

Glioblastoma strikes roughly twelve thousand people each year in the United States. It is a fast-growing tumor that thrives in oxygen-starved tissue. The cancer creates these hostile conditions deliberately, disrupting the blood vessels in the brain so that oxygen delivery plummets. Half of those diagnosed are dead within fourteen months. Only five percent survive five years past diagnosis. The former presidential candidate John McCain was among them, dying in 2018 just over a year after his tumor was discovered.

The Pennsylvania team, led by chemist Megan Matthews, set out to understand how hydralazine actually works at the molecular level—something that had never been fully explained in the seventy years since its approval. The drug was licensed in an era when regulators required only proof of effectiveness, not proof of mechanism. What they found was that hydralazine binds to an enzyme called 2-aminoethanethiol dioxygenase, or ADO. This enzyme activates when oxygen runs low and breaks down a protein that helps cells survive in those starved conditions. By blocking ADO, hydralazine causes blood vessels to widen and pressure to drop.

Then the researchers asked a second question: if hydralazine blocks this oxygen-sensing pathway in blood vessels, what happens if you apply it to cancer cells that depend on that same pathway? In laboratory experiments, they found that the drug blocked ADO in glioblastoma cells just as it did in vessel cells. The cancer cells lost their ability to maintain the proteins they need to survive in low-oxygen environments. The result was cellular senescence—a dormant, non-dividing state in which the tumor cells simply stopped growing.

This is early work. The experiments happened in petri dishes, not in living brains. No human has yet taken hydralazine as a glioblastoma treatment. But the finding matters because it points toward a drug that is already manufactured, already proven safe in millions of patients, and already cheap. Current treatment for glioblastoma relies on surgery, chemotherapy, and radiation—interventions that typically ease symptoms or extend life modestly, but rarely cure the disease.

Matthews described the discovery as rare: an old cardiovascular drug teaching new lessons about the brain. She and her team published their work in Science Advances and noted that they are searching for more of these unexpected connections, unusual links that might yield solutions to diseases that have resisted conventional approaches. The next step would be animal studies, then human trials. But for a cancer that kills so quickly and so thoroughly, even a promising laboratory finding carries weight.