DRUG ‘blew up’ tumours in tests on mice.
A “smart bomb” with the potential to destroy cancers of all kinds could be tested on patients within two years.
The drug, derived from the autumn crocus flower, is designed to “detonate” and become active only after reaching a target tumour.
It can circulate in the bloodstream, wiping out cancers that have spread while leaving healthy tissue unharmed. Scientists believe the compound should be effective against all forms of solid tumour.
In the laboratory it was successfully used to treat breast, bowel, lung and prostate cancers in mice. Half the animals appeared to be completely cured after just one injection of the drug, and tumours were slowed in every mouse tested.
The key to the drug is the way it is activated by an enzyme tumours use to invade surrounding tissue.
Once active, it destroys blood vessels feeding the tumour and causes the cancer to starve to death.
Professor Laurence Patterson, who heads the research team, said: “What we've designed is, effectively, a ‘smart bomb' that can be targeted directly at any solid tumour to kill it without appearing to harm healthy tissue.”
Talks are now taking place to raise the £3m (€3.5m) needed to bring the drug to trial. Patients at St James's University Hospital, Leeds, could be the first to try the treatment, possibly in the next 18 to 24 months.
The drug is based on colchicine – a highly toxic substance in the flowers, leaves and seeds of the autumn crocus. Extracts from the plant have a history of use both as a herbal medicine and poison dating back to ancient Egypt and Greece.
Most commonly, colchicine has been used to treat gout. Previous attempts to employ it to fight cancer have failed because of the compound's extreme toxicity. Prof Patterson's team found a way of rendering the drug harmless until it was exposed to a protein only found in tumours.
The protease enzyme, MMP1, is used by the tumour to “dig” a path through surrounding tissue, allowing it to expand and develop new blood vessels.
“Our novel delivery method uses the presence of this active MMP to activate the drug, which attacks and breaks down cancer blood vessels, destroying the tumour's lifeline,” said Prof Patterson.
In the mouse studies, human tumour fragments were grafted on animals with suppressed immune systems. Without treatment, the mice quickly develop spreading cancer and die. “Sometimes the treatment is so effective that you actually remove the tumour's ability to grow completely,” said Prof Patterson.
”We were able to cure, in some studies, half the mice of their cancer. These mice no longer had any tumours growing in them, and they remained healthy for the 60 or so days the experiment lasted.”
Every mouse given the treatment responded by at least experiencing a slowing of cancer growth.
Tests confirmed that the drug was not activated anywhere outside the tumour, and healthy tissue was not affected.