WITHIN just eight days of starting a novel gene therapy, David Aponte's \"incurable\" leukaemia had vanished. For four other patients, the same happened within eight weeks, although one later died from a blood clot unrelated to the treatment, and another after relapsing. <\/p>\n
The cured trio, who were all previously diagnosed with usually fatal relapses of acute lymphoblastic leukaemia, have now been in remission for between 5 months and 2 years. Michel Sadelain of the Memorial Sloan-Kettering Cancer Center in New York, co-leader of the group that designed the trial, says that a second trial of 50 patients is being readied, and the team is looking into using the technique to treat other cancers. <\/p>\n
The key to the new therapy is identifying a molecule unique to the surface of cancer cells, then genetically engineering a patient's immune cells to attack it. <\/p>\n
In acute lymphoblastic leukaemia, immune cells called B-cells become malignant. The team were able to target a surface molecule known as CD19 that is only present on B-cells. Doctors extracted other immune cells called T-cells from the patients. These were treated with a harmless virus, which installed a new gene redirecting them to attack all cells bearing CD19. When the engineered T-cells were reinfused into the patients, they rapidly killed all B-cells, cancerous or otherwise. <\/p>\n
\"The stunning finding was that in all five patients, tumours were undetectable after the treatment,\" says Sadelain. <\/p>\n
He reckons that the body should replenish the immune system with regular T-cells and healthy B-cells after a couple of months. However, the patients received donated bone marrow to ensure they could regrow a healthy immune system (Science Translational Medicine, doi.org\/kwz). <\/p>\n
The treatment is not the first to re-engineer T-cells to attack a form of leukaemia. Last year, an international company called Adaptimmune used the approach to treat 13 people with multiple myeloma it left 10 in remission. <\/p>\n
\"Although it's early days for these trials, the approach of modifying a patient's T-cells to attack their cancer is looking increasingly like one that will, in time, have a place alongside more traditional treatments,\" says Paul Moss of Cancer Research UK. <\/p>\n
Sadelain's team is now investigating the scope for attacking other cancers. Where no single surface molecule is unique to a cancer, he is seeking to target pairs of molecules that only occur together on cancer cells. In January, he demonstrated this approach by wiping out human prostate tumours implanted in mice, using T-cells engineered to target two surface molecules (Nature Biotechnology, doi.org\/kw2). <\/p>\n
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