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| Extracts from the Autumn crocus are already used to treat gout |
The search
for more effective cancer treatments may soon harness the healing power of the
Autumn crocus.
Researchers
are poised to start clinical trials with a new "smart bomb"
treatment, derived from the flower, targeted specifically at tumours.
The
treatment, called colchicine, was able to slow the growth of and even
completely "kill" a range of different cancers, in experiments with
mice.
The
research was highlighted at the British Science Festival in Bradford.
The team
behind it, from the Institute for Cancer Therapeutics (ICT) at the University
of Bradford, has published the work in the journal Cancer Research.
The native
British Autumn crocus, otherwise known as "meadow saffron" or
"naked lady", is recorded in early herbal guides as a treatment for
inflammation.
This is
because it contains the potent chemical colchicine, which is known to have
medicinal properties, including anti-cancer effects.
But
colchicine is toxic to other tissues in the body, as well as cancer, so until
now its use has been limited.
The
researchers at ICT have now altered the colchicine molecule so it is inactive
in the body until it reaches the tumour.
Once there,
the chemical becomes active and breaks up the blood vessels supplying the
tumour, effectively starving it.
This effect
is made possible because of enzymes that all tumours produce, whose usual
function is to break down the normal cells nearby, allowing the tumour to
spread.
The
modified colchicine molecule has a protein attached to it that makes it
harmless. But the tumour enzyme specifically targets the protein and removes
it.
The
colchicine is then activated, and the process of breaking down blood vessels
and starving the cancerous cells begins.
Optimistic
but cautious
One of the
things that may make this drug so effective, Professor Patterson said, is that
it will be "only active in the tumour, and not cause damage to normal
tissue".
Because the
enzyme necessary to activate the toxic colchicine is produced only by solid
tumours, it may be possible to treat cancers effectively with virtually no side
effects to the rest of the body.
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| The "smart bombs" do not begin to act until they reach tumour tissue |
Moreover,
as the drug will be activated wherever the enzyme is produced, the delivery
mechanism should allow treatment of particularly problematic cases of
metastasis, where the cancer spreads from its initial site.
Pre-clinical
tests in mice have shown startlingly successful results.
"What
we're looking for is a delay in the growth of the tumour," said Professor
Patterson.
"But
sometimes the treatment is so effective that in half of the studies, the mice
appeared to be cured of their cancer. All mice responded to the
treatment."
Just one
dose of the colchicine produced this remarkable effect. But if it passes
clinical tests, the researchers believe it will be used alongside existing
cancer treatments, as part of the complex process of tackling the disease.
The
researchers hope that the treatment will enter the initial stage of clinical
testing at St James's Hospital in Leeds within the next 18 months.
Professor
Patterson said that he was "very optimistic about the opportunities of the
treatment, but still cautious because everything done to date has been in the
laboratory".
Paul
Workman, head of cancer therapeutics at the Institute of Cancer Research,
called the work an "interesting new approach".
"The
project is still at quite an early stage but the results so far look promising
in the laboratory models that have been studied," he said.
"If
confirmed in more extensive laboratory studies, drugs based on this approach
could be very useful as part of combination treatments for various
cancers."
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