A new type of cancer treatment which kills malignant cells but leaves healthy cells unscathed has shown remarkable promise in its first trial.
More than half the 60 patients who received the targeted treatment saw their tumours shrink or stabilise, despite having previously tried other therapies which had failed to curb the progress of their disease. One patient who had advanced cancer is still in remission after two years.
The findings are announced today in the New England Journal of Medicine, which has taken the unusual decision to publish the small trial at such an early stage because of its "important results". An accompanying editorial says they "point to a new direction in the development of anti-cancer drugs".
The announcement comes five days after scientists at the Mayo Clinic in the US reported success with a new drug for prostate cancer. Two patients who had "inoperable" tumours were treated with the drug ipilimumab, a monoclonal antibody that stimulates the immune system. After one infusion, their tumours shrank enough to be surgically removed and both men have made a full recovery.
The latest development involves a different drug, olaparib, which works in a different way by targeting the genetic defect that causes cells to turn cancerous. In a process called "synthetic lethality", the drug has been engineered to chemically inhibit one type of gene, which then acts with the abnormal cancer gene to kill cancer cells in which both are present.
Initial tests have been carried out in patients with inherited breast, ovarian and prostate cancer caused by mutations in the BRCA1 and BRCA2 genes. People with these genetic mutations – about one in 500 people – have a high risk of developing cancer, of up to 80 per cent in the case of breast cancer.
Johann de Bono, a scientist at the Institute of Cancer Research and the leader of the study conducted in the UK and the Netherlands, said the trial showed "very impressive results".
"It's giving patients who have already tried many conventional treatments long periods of remission, free from the symptoms of cancer or major side effects." Professor Stan Kaye, the joint lead researcher from the institute, said: "This is a very important drug for the the treatment of BRCA1/2-related cancer. The next step is to test the drug on other more common types of ovarian and breast cancers where we hope it will be just as effective."
Julian Lewis, 62, who was diagnosed in 2004 with prostate cancer which had spread to his bones, has been on olaparib for two years. The drug has held his prostate cancer in check and the cancer in his bones "seems almost to have disappeared", he said.
Married with three daughters, he lives in Oxford and works as a cancer researcher himself. He is a BRCA2 mutation carrier and his sister died of ovarian cancer.
"It has always been the dream of cancer research to discover drugs that will kill the cancer cells while leaving healthy cells unharmed," he said.
"Now we have the tools in terms of genes to discover what has gone wrong in the cells of a cancer to make them misbehave. If you can pinpoint the key mutation that makes them dangerously different, you can use that to kill the cells selectively. In other words you can turn the weapon of the mischief-maker against the mischief-maker itself."
The drug is now being tested in further larger trials across the world.