A pioneering vaccine to treat breast cancer using a patient’s own cells has been developed by scientists.
The vaccine was described as “promising” after 85 per cent of women with a ductal carcinoma in situ (DCIS) – the most common non-invasive form of the disease – were still showing protection after four years.
Researchers at the University of Pennsylvania in the United States enrolled 27 patients and isolated specialised white cells using standard techniques similar to blood donation.
The cells were manipulated in the laboratory to allow the immune system to recognise the cancerous cells as foreign and attack them.
Each patient received four weekly injections of their personalised vaccine and had surgery two weeks later to remove any remaining disease.
The study, published in the Journal of Immunotherapy, compared pre-vaccination samples with post-vaccination samples and found five patients, almost 20 per cent, had no disease visible, indicating their immune system had wiped out the tumour.
Of the remaining 22, damaging proteins had been eliminated in 11 and reduced by 20 per cent or more in another two.
Study leader Dr Brian Czerniecki said: “We are continuing to see this pattern in our second, ongoing trial.”
The researchers say the results provide new evidence therapeutic breast cancer vaccines may be most effective for early, localised disease, and when the treatment goes after a protein critical to cancer cell survival.
Dr Czerniecki said: “I think these data more than prove that vaccination works in situations where the target is right.
“Previous vaccines targeted tissue antigens that were expressed on the cancer cells, but were not necessary for tumour survival.
“So a vaccine response would cause the tumour to just stop expressing the antigen and the tumour would be fine.
“Here we are going after HER2/neu, which is critical for survival of early breast cancers. If we knock it out with the immune response, we cripple the tumour cells.”
Importantly, some patients maintained their immune responses for more than four years, meaning they continue to have some protection from recurrence.
The results of the study show the vaccine is safe and relatively easy for the women, with only low-grade side effects.
The most common side effects were malaise (72 percent), injection site soreness (59 percent), chills or rigors (38 percent), fever (28 percent) and headaches (24 percent).
While the numbers of patients treated in the trial are relatively small, Dr Czerniecki believes they will have some idea whether the vaccination reduces the risk of disease recurrence within the next two years.
Meanwhile, the team continues enrolling patients in a larger study and is designing another study to test the approach in women with early invasive breast cancer.
There are dozens of cancer treatment vaccines in trials for use in breast cancer.
They aim to shrink the tumour, to prevent it from returning or to eliminate cancerous cells that have not been erradicated by treatment.
The vaccines must flag up the cancerous cells to the immune system so they can be recognised as something that needs to be destroyed.