A POSTMASTER dying of the most dangerous form of skin cancer is one of two men to have been saved after their white blood cells were genetically engineered to fight their tumours.

The trial in the US provides the first direct evidence that normal immune system cells can be altered genetically to become tumour-hunters, raising the prospect of a new generation of treatments for cancer.

While the therapy has been tried on only the most virulent form of skin cancer, malignant melanoma, which accounts for about 3 per cent of cancers in Britain, scientists are convinced that it should work eventually for other tumours, such as those of the breast or lung.

The team at the US National Cancer Institute (NCI) have already tailored human white blood cells to recognise and destroy other cancers in the laboratory and are planning to test these on patients soon.

The potential implications for malignant melanoma are also significant because the incidence of this type of cancer, which accounts for about 10 per cent of skin tumours, is also growing faster than any other cancer in the UK.

More than 8,000 new cases are diagnosed each year — three times the figure in 1975 — and rates are increasing particularly steeply among young people. There were 1,777 deaths from the disease in 2004.

The researchers said that the technique would not yet work for every patient and that it would be premature to regard it as a “silver bullet” cure.

Of 17 melanoma patients who were given cells tailored to fight their tumours, only two responded. Even so, these two cases offer proof of the principle that the adapted cells can survive, then shrink tumours.

“This represents the first time that gene manipulations have been shown to cause tumour regression in humans,” Steven Rosenberg, of the NCI, who led the work, said.

One of the two patients who has been successfully treated is Mark Origer, 53, a father of three from Watertown, Wisconsin. He was diagnosed with a malignant melanoma seven years ago. By 2004, with all treatments having failed, the cancer had spread to his liver, lung and lymph nodes. “I was hopeful every time I tried a new treatment. I hoped it would be the end of my disease,” he said. “But nothing worked. It felt defeating.”

It was then that he enrolled for the clinical trial. “I’m cured for now,” he said, after a check-up from NCI doctors last week. “I know how fortunate I am to have gone through this and responded.”

The scientists are not yet willing to give a long-term prognosis for the two men, but Mr Origer has achieved his first target. When he was treated in December 2004, he hoped to survive for the wedding of his eldest daughter, Katie, whom he walked down the aisle last autumn. “She wanted me to be there for her, and she wanted me to be here for me. There was a lot of concern from all my children,” he said.

Stephen Simpson, senior editor of Science, which published the results yesterday, said: “This work marks an important next step in harnessing the power of our immune systems to fight cancer.”

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