US scientists have reported the first successful use of gene therapy to treat cancer. Two men with advanced melanoma are now free of the disease, after taking part in a trial based at the National Cancer Institute in Bethesda, Maryland. The new technique involves injecting patients with genetically modified versions of their own immune cells, with the aim of specifically destroying the cancer cells. Although 15 other trial participants did not respond to the treatment, the team hope that improvements to the technique will increase future success rates.
The new method relies on boosting the natural ability of immune system 'T-cells' to recognise and destroy abnormal cells. The team, lead by Steven Rosenberg, first harvested T-cells from the patients, and multiplied them in the lab. Then they used a harmless virus to deliver melanoma-specific receptor genes to the cells, which make proteins that sit on the surface of the T-cells and allow them to target melanoma cancer cells. The scientists then returned the modified cells back to the patients, where they began to attack the tumour cells.
All of the trial participants had an advanced form of the disease, and were only expected to live for three to six months. But in two of the patients, the new treatment dramatically shrank their tumours, and prevented the cancer spreading to other organs, with the result that they have now been in remission for over a year. For 53-year-old Mark Origer from Wisconsin, it meant that he was able to attend his daughter's wedding last autumn. The treatment left him with just one small cancerous spot in his liver, which surgeons have since removed. 'I am cured for now', he said', adding 'I know how fortunate I am to have gone through this and responded to this. Not everybody's that lucky'. Professor John Toy, medical director of the charity Cancer Research UK, called the results 'preliminary but promising'. But he also cautioned that 'it's important to realise that we are not looking at a "miracle cure" for all cancers'.
The study, published online in the journal Science, provides 'proof of principle' for a new way of tackling tumours that do not respond to conventional surgical, chemotherapy or radiotherapy treatments. The scientists are now working to increase the efficiency of the technique. 'We now have receptor proteins that are 100 times more powerful', Rosenberg told New Scientist. They have also isolated receptors that recognise other common cancers, such as breast and prostate cancer, which they hope to use in future trials.