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Last Updated: Sunday, 14 January 2007, 00:21 GMT
Drug 'strangles cancer's spread'
Glivec is normally used to treat leukaemia
The spread of prostate cancer can be halted with a drug which "strangles" tumour cells by cutting off their blood supply, a study has suggested.

Tests on mice showed that using the leukaemia drug Glivec helped stop prostate cancer spreading to the bone.

Prostate cancer experts said the study was promising, but more work was needed for the benefits to men to be clear.

The University of Texas research was published in the Journal of National Cancer Institute.

Prostate cancer is the most common cancer in men in the UK.

About 32,000 men are diagnosed and around 10,000 die from the disease every year.

Cell death

In the US research, mice were injected with multiple drug-resistant prostate cancer.

Some were then treated with a combination of the chemotherapy drug paclitaxel and Glivec (also known as imatinib), while others were given no treatment.

Bone tumours grew in only four out of 18 animals who received the drug treatment, but tumours grew in all 19 who were not treated.

Developing drugs to destroy the blood supply to tumours is a promising approach and clearly has had good results so far
Chris Hiley
The Prostate Cancer Charity

Paclitaxel (Taxol), which causes cancer cells to kill themselves, is already a key treatment for prostate cancer, but tends to become ineffective as resistant tumour cells spread, so doctors are seeking other drugs to use with it.

Glivec works by blocking signals that allow cells to multiply.

The researchers found the drug blocked the mechanism that triggers the growth of blood vessels linked to tumours.

It targets the endothelial cells lining the walls of existing blood vessels, preventing them sprouting new branches, by inactivating a receptor called PDGF-R on the blood vessel cell surface .

This led to the blood vessel cells dying, followed by the tumour cells one to two weeks later.

'Seed and soil'

Lead researcher Dr Isaiah Fidler, director of the Cancer Metastasis Research Centre, at the University of Texas, in Austin, said: "We didn't attack the tumour, we attacked the blood vessels.

"We target and destroy the vasculature that provides oxygen and nutrients to tumour cells."

Most cancer cells are known to die once they have moved away from the original tumour.

Metastatic (secondary) cancer that develops away from that starting point originates from less than 1% of a tumour's cells and can even arise from a single cell.

This is known as the "seed and soil" hypothesis - the seeds being the metastatic cells.

Dr Fidler said: "Here, we attack the soil. The seeds can be resistant. Kill the endothelial cell, you kill the soil."

Chris Hiley, head of policy and research at The Prostate Cancer Charity, said: "This research is at a relatively early stage in developing a possible new treatment.

"The study was completed on mice, so it will be some while before we know how well these studies transfer to men with prostate cancer and data is available from extensive trials, for review."

She said: "This further work is likely to take some years, but developing drugs to destroy the blood supply to tumours is a promising approach and clearly has had good results so far.

"The researchers will need to discover how effective the new treatment is and what the side effects might be before we can be more certain of its significance in men."

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