Cancer drug fuels tumour growth
New research shows that a cancer drug designed to stunt tumour growth actually makes tumours grow faster if given at too low a dose.
Researchers in the UK are investigating anti-angiogenesis drugs, which are designed to prevent the proliferation of blood vessels that occurs around cancer tumours.
Avastin and Sutent, which act in a similar way, have been proven to work and were not covered in this research. But cancer experts say the study, published in Nature Medicine could help make those drugs more effective.
The researchers focused on a drug called Cilengitide which is designed to prevent blood vessel cells sticking together and moving - an important part of angiogenesis.
Previous tests on people have found that a few patients with brain tumours benefited from high doses of the drug, but that it failed to work for most.
In this research, tests carried out on mice showed that low doses of Cilengitide actually stimulated the growth of cancers.
Further investigation showed it did this by switching on a molecule called VEGFR2, which triggers the angiogenesis process.
That is significant because although when a patient is initially given a drug, its level in the blood rises quickly ensuring a big dose goes to the tumour, after a while levels start to fall as the body begins to deal with the drug.
This is likely to be why trials of the drug have shown such poor results.
The research also has implications for the existing drugs Sutent, used to treat kidney cancer, and Avastin, for colorectal cancer. They work by the same process, but on different targets.
At the moment, they can extend a patient's life by several months. Experts hope that this research could lead to a better understanding of the drugs' mechanisms and so to ways of making them more effective.
