Chemotherapy and Prostate Cancer: BBC

BBC reports the following:

Drug 'strangles cancer's spread'
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."