Results from early, small studies suggest that the vaccine, injected once a month, can keep the disease at bay once patients have had chemotherapy and are in remission.
If the protective effect is confirmed, the vaccine could eventually be used against the disease in its earlier stages. Dr David Miles, co- head of the Imperial Cancer Research Fund's breast cancer unit at Guy's Hospital, London, and co-ordinator of the British arm of the study, said: "If we can demonstrate that this vaccine contributes to treatment of the disease in its advanced state then maybe we should be using it before we get to that stage."
The vaccine, Theratope, has been developed by a Canadian biotechnology company, which has isolated a molecule associated with breast cancer. It hopes the molecule will kick-start the body's immune system into fighting the disease.
"Our early data shows it is not going to eradicate the disease, but, for women who have undergone chemotherapy, it will act as an adjunct to hopefully keep the disease at bay, and prolong patients' lives," Dr Miles said.
The new vaccine works by targeting abnormalities in a type of sugar molecule, known as STn, found in breast cancer but not normally traced by the body's immune system.
Scientists hope that by signalling the presence of that abnormality to the body using Theratope, the immune system will be provoked into producing the antibodies necessary to attack the disease.
The British arm of the trial will include 200 women who will be treated at Guy's Hospital. Women will be selected on the basis of very specific criteria, and patients wanting to be considered would have to be referred by their own GPs to Dr Miles's team.
If proved successful, the vaccine could be licensed in four to five years.
The vaccine trial is one of three research projects being undertaken by the research fund group at Guy's aimed at stimulating the female immune system to fight breast cancer.
Laboratory studies into the gene for mucin, a molecule that is changed in breast cancer cells, are intended to make the molecule recognisable by the body's immune system so that it is open to attack.
Scientists have identified the chemical building blocks that make up the mucin core and, by giving patients the synthesised versions of them, can help the body to recognise that the mucin in the cancer cells is abnormal.
The third project is based on a gene therapy approach using a modified form of the Vaccinia virus. When a virus invades the body, its genetic material enters the cells. In the Vaccinia trial, the modified virus is used to transport the gene for mucin into the patient's cancer cells, providing a target for the body's immune system.
The trial is being carried out on women with advanced breast cancer and the treatment is being given by injection every three to four weeks. The primary aim is to keep the disease under control, but scientists also hope treatment may cause the tumours to shrink.Reuse content