By Michelle Roberts
Health editor, BBC News online
A commonly used blood pressure drug could help fight cancer by opening up blood vessels in solid tumors.
Used beside conventional cancer-fighting drugs, it could improve life expectancy, experts believe.
Following successful testing in mice, doctors plan to give losartan to patients with pancreatic cancer to see if it can tackle this hard-to-treat disease, Nature Communications reports.
Currently, only 5% of pancreatic cancer patients survive for at least 5 years.
This is partly because only one in 10 people with the disease has a tumour that is operable.
Investigators at the Massachusetts General Hospital in the US are currently recruiting volunteer patients with inoperable pancreatic cancer to test out the new drug combination of chemotherapy plus losartan.
Although the treatment will not cure them, the researchers hope it will give the patients more months or years of life than they might otherwise get.
Losartan has been used for more than a decade as a safe blood pressure medication.
It works by making the blood vessels relax or dilate so that they can carry more blood, easing pressure.
The Massachusetts team found that the drug was beneficial in mice with breast and pancreatic cancer.
It improved blood flow in and around the tumors allowing more of the chemotherapy drugs to be delivered to their target.
Mice given this treatment, rather than standard chemotherapy alone, survived for longer.
Dr Emma Smith of Cancer Research UK said: "This interesting study in mice sheds light on why drugs for hypertension might improve the effectiveness of chemotherapy, but we don't yet know if they work exactly the same way in people.
"The fact that these drugs are already widely used to treat high blood pressure will hopefully cut down the amount of time it will take to test their potential in treating cancer but they may not be safe for all patients or when combined with other cancer treatments, so we need to wait for the answers from clinical trials which are already under way."