TWO men originally given six months to live are clear of cancer after treatment with genetically engineered immune cells.
In a preliminary study of 17 participants with advanced melanoma, the pair were declared clinically free of the disease one year after receiving the treatment, which transformed normal white blood cells into 鈥渢umour hunters鈥�.
When the body successfully detects melanoma, its immune cells produce receptor proteins on their surface that pick up on the presence of a chemical marker called MART-1 on the surface of the tumour cells. So Steven Rosenberg, chief of surgery at the US National Cancer Institute in Bethesda, Maryland, and colleagues, set out to modify T-cells 鈥� a type of white blood cell 鈥� to recognise the MART-1 protein.
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The researchers first engineered a retrovirus to carry the gene responsible for the production of this protein. They then removed immune cells from 17 melanoma patients and exposed the cells to the engineered virus. The virus integrated itself into the DNA of these cells, causing them to start expressing the receptor proteins.
Rosenberg鈥檚 team then infused the engineered immune cells back into the patients, all of whom had failed to respond to conventional therapies and were thought likely to die from the disease within six months. The modified T-cells survived in 15 of the patients, but in only two of them did the cells thrive, and in these two the tumours disappeared (Science, DOI: 10.1126/science.1129003). Rosenberg says he has treated thousands of patients with advanced melanoma and never seen regression without treatment. 鈥淚t gives hope that with further refinement we would be able to expand this to treat other tumours,鈥� says Len Lichtenfeld of the American Cancer Society in Atlanta, Georgia.
That is what Rosenberg is doing. 鈥淲e now have receptor proteins that are 100 times more powerful,鈥� he says. The group hopes that the US Food and Drug Administration will grant approval within a month to test receptor proteins for other tumours, such as breast, lung or prostate cancers.
Lichtenfeld warns against undue optimism. While this personalised treatment is encouraging, and a boost for gene therapy, there is a long way to go before it becomes widely available, he says.
