The discovery of a molecule that helps a particularly dangerous form of breast tumour grow and spread could lead to new treatments, suggest UK researchers.
The molecule, known as alpha v beta 6, could be used both to identify at-risk patients and develop new treatments, say scientists.
“This study could pave the way for new treatments and bring us closer to our goal of preventing half of the deaths from breast cancer by 2025”
A study found high levels of alpha v beta 6 in 40% of tumours in women with HER2 positive breast cancer, a form of the disease that does not respond to conventional hormone therapy.
These patients were twice as likely to die within five years of diagnosis as those with low levels of the molecule.
In experiments on mice with the same type of breast cancer, scientists used an antibody drug to block activity of alpha v beta 6.
Combining the antibody with the drug trastuzumab (Herceptin), which targets the cancer-driving HER2 protein, completely eradicated the animals’ tumours after six weeks of treatment.
Researcher Dr Kate Moore, from Queen Mary University of London’s Barts Cancer Institute, said: “We found that simultaneously targeting alpha v beta 6 and HER2 in mice with tumours grown from human breast cancer cells greatly improved the effectiveness of Herceptin − even eliminating tumours that did not respond to Herceptin alone, which could have the potential to improve treatments for patients with these highly aggressive cancers.”
Using the antibody on its own reduced the size of tumours in the mice by 94.8%. In comparison, treatment with Herceptin alone led to a 77.8% reduction.
Up to 70% of women with HER2-positive breast cancer either do not respond to Herceptin or develop resistance to the drug, leaving up to 7,000 women a year in the UK with limited treatment options.
Dr John Marshall led the Barts Cancer Institute team, which received funding from the charity Breast Cancer Campaign and the Medical Research Council.
He said: “The results of this pre-clinical study suggest that targeting the alpha v beta 6 molecule may enhance the effectiveness of Herceptin − and that a combination treatment could be effective for patients where Herceptin alone has not worked.
“High alpha v beta 6 levels could be tested for in routine biopsies to identify which women are at a high risk of metastasis (cancer spread), ensuring these women can receive personalised treatment, improving their chances of survival.”
The research findings have been published online in the Journal of the National Cancer Institute.
Baroness Delyth Morgan, the chief executive of Breast Cancer Campaign, said: “There is a desperate need for drugs which work in new ways to give the thousands of women diagnosed with HER2-positive breast cancer the best possible chances of surviving the disease.
“This study could pave the way for new treatments and bring us closer to our goal of preventing half of the deaths from breast cancer by 2025, through improved and personalised treatments,” she said.
The charity has just launched a new campaign, “spread the word to stop the spread”, highlighting the fact that 12,000 women still die from breast cancer each year in the UK.