Drugs `kill cancer tumours'

A COMBINATION of drugs which has been found by researchers in the United States to kill tumours in mice was last night hailed as a significant breakthrough in the search for a cure for cancer. The news took Wall Street by storm as shares in the company hoping to market the drugs leapt nearly six-fold. The drugs, angiostatin and endostatin, work by cutting off the blood supply to the tumours. When the drugs were given intravenously to mice, tumours shrunk before disappearing altogether. They also appear to prevent the spread of tumours.

Dr Judah Folkman, a Harvard professor and researcher at Boston Children's Hospital who discovered the treatment, called the combination of proteins "very promising", but warned that their success might not work on humans. "We have to be careful with expectations," he said.

It is impossible to speculate which types of human cancer might respond to the new drugs, but Dr Folkman said that they had eliminated forms of colon, prostate, breast and brain cancers in mice. So far, he added, researchers had not found a form of cancer in mice which they could not defeat.

Dr Richard Klausner, director of the US National Cancer Institute, said the initial studies were remarkable and that he hoped to start testing on a small number of humans within a year. "I am putting nothing on higher priority than getting this into clinical trials," he told the New York Times.

Shares in Entremed, of Maryland - which is hoping to market the two drugs - started trading on the Nasdaq stock exchange at $12.06, at one point reached $85, but later settled back to $59.

In London, Professor Karol Sikora, head of the World Health Organisation's cancer programme, said it was a "very exciting development" but warned that it would be a long time before it was available as a treatment.

"It is one of the most exciting things that is on the horizon, but if people have cancer now, I'm afraid it won't help them at all," he said. "It will be two years before we know if it works. We have been this close to success before and it just hasn't panned out.

"There is a long way to go between the animal experiments which have been done successfully and getting a drug which works successfully for a cancer patient each time. It very definitely works in mice, but the trouble is we don't know whether you can transfer this to humans," Professor Sikora said.

Professor Adrian Harris, head of the Imperial Cancer Research Fund medical oncology unit, and an expert on angiogenesis, said: "This is an extension of previous work on endostatins which was published last year. Endostatin, when given alone, has shown to have an anti-tumour effect, as has angiostatin. The two drugs work using different mechanisms, and using them together has a marked difference on tumour growth in experimental systems."

The development of the drugs - which are fragments of protein found in human blood - is the end of a 30-year research process.

Tumours need blood vessels to provide them with the nutrients and growth factors, which they use to grow unchecked. Endostatin, the most powerful inhibitor of blood-vessel growth known, is a protein that has to be injected. However, it is also expensive and may have long-term toxic side-effects

The new proteins eliminate the flow of blood to the tumour.In addition, tumours treated with endostatin do not develop a resistance to the drug, as they can do with chemotherapy drugs.

In one experiment, when protein treatments were stopped among some mice, their tumours returned. But once the drugs were re-administered continuously, the tumours receded.