"Smart bomb" drug to target cancers

A "smart bomb" with the potential to destroy solid cancers of all kinds could be tested on patients here within two years, researchers said Monday. The drug, derived from the autumn crocus (Plant), 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, currently known by the code-name ICT2588, 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 tumour growth was 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 at the University of Bradford, northern England, 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 with an unnamed funder to raise the 3 million pounds needed to bring the drug to trial. Patients at St James's University Hospital, Leeds, northern England, could be the first to try the treatment, possibly in the next 18 to 24 months. The drug, known as a "vascular disrupting agent" (VDA), 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. The new drug belongs to the same medicine family as paclitaxel, the most widely used chemotherapy agent in the world, which is derived from the bark of the Pacific yew tree. 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. Many of the latest targeted cancer drugs are designed to attack specific types of cancer, or even cancers in patients with a precise genetic make-up. Cancer therapeutics at the University of Bradford, said men with advanced prostate cancer might be among the first patients to benefit, assuming clinical trials are successful.