British flower 'smart bomb' drug to fight cancer
A substance found in a native British flower has been turned into a powerful "smart bomb" drug that can work against a range of cancers.
The drug, based on colchicine found in the autumn crocus, cuts off the blood supply to solid tumours, curbing their growth and stopping cancer cells from spreading to other parts of the body.
Tests on laboratory mice have shown that the drug is highly effective at attacking tumours from a range of diseases such as sarcomas and cancers of the breast, colon, lung and prostate.
The drug is also designed to target solid tumours directly, leaving healthy tissue unaffected, according to Professor Laurance Patterson, director of Bradford University's Institute for Cancer Therapeutics.
"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," Professor Patterson said.
"What is also new about our approach is that we are effectively targeting the blood supply of the tumour," he said. "If you can starve the tumour of that blood supply, then you can shut off its ability to grow and, indeed, you also shut off its ability to move around the body."
The drug is well-known as having anti-cancer properties, but is normally toxic to healthy cells and so has had limited potential in medicine. The trick used by the Bradford scientists is to attach colchicine to another molecule that renders the drug inactive until it comes into contact with a one of a class of enzymes called matrix metalloproteinases (MMPs), which are used uniquely by tumours to burrow into the body's healthy tissue, said Kevin Adams of the Bradford institute.
"The drug is inactive until triggered by the activity of an enzyme that is always found in the tumour environment but not elsewhere. Triggering releases a potent, anti-cancer agent which destroys the tumour's blood vessels, effectively starving the tumours to death, a process known as haemorrhagic necrosis," Dr Adams said.
Tests on specially bred mice that have human cancerous tumours have shown that the drug can have a "cure rate" of greater than 70% after a single dose, he said.
The next stage is a clinical trial to test its safety, which is hoped to be conducted within 18 months at St James's University Hospital in Leeds.
Extracts from the plant have an ancient history of use, both as a herbal medicine and poison.
Most commonly, colchicine has been used to treat gout.
Previous attempts to employ it to fight cancer have failed because of its toxicity.
The new drug belongs to the same family as paclitaxel, a widely used chemotherapy agent.