Smallpox virus gives new hope in breast cancer fight
A relative of the smallpox virus may be an effective weapon against one of the deadliest forms of breast cancer, research has shown.
Laboratory tests showed more than 90pc of triple negative breast cancer (TNBC) cells treated with the vaccinia virus were destroyed within four days.
In mice with the disease, one strain of the virus cleared away 60pc of tumours while the extent of those left was dramatically reduced.
Vaccinia virus is best known as the basis of the vaccine that eradicated smallpox. Although closely related to the variola virus that causes smallpox, it is generally harmless to humans.
TBNC is difficult to treat because it lacks three types of molecular "receptor" that can be targeted by existing hormonal and antibody treatments.
The disease mostly occurs in younger women and is responsible for 10pc to 20pc of all breast cancer cases. TBNC tends to be aggressive and often recurs after chemotherapy.
The virus targets a protein tumours use to promote the formation of blood vessels that support their growth.
TBNC has high levels of the protein, known as vascular endothelial growth factor.
Lead researcher Dr Sepideh Gholami, from Stanford University in California, US, said: "The reason we used the vaccinia virus is that it is a member of the smallpox family, and, as we know, smallpox vaccine has been given to millions of people to eradicate smallpox. So we thought it would be safer and more promising in terms of a clinical trial and actual application."
The findings were presented yesterday at the American College of Surgeons' Annual Clinical Congress in Chicago.
Exposing mice with TNBC tumours to the virus led to "extensive destruction" of the cancer over a period of three weeks, said the scientists.
"Based upon pathology, we could see that at least 60pc of the tumours were completely regressed and the other 40pc had very little areas of tumour cells present with a lot of necrosis, which is a sign that the tumour was responding to therapy," said Dr Gholami.
As well as infecting and breaking down cancer cells, the virus also blocked the growth of tumour blood vessels.
Ultrasound imaging revealed a "significant reduction" in blood flow to tumours. The network of blood vessels supplying tumours with nutrients and oxygen shrank to half its normal size in treated animals.
The next step will be to design a clinical trial and assess the safety of the virus in patients, Dr Gholami added.
Meanwhile, it also emerged yesterday how a simple blood test could provide a more effective way to test for early signs of breast cancer than using an X-ray to spot a lump, researchers have said.
Scientists hope the blood test will be more accurate than mammograms, and will also be able to detect whether breast cancer patients are likely to relapse and what drugs their type of tumour will respond to.
A clinical study is about to begin in the UK's largest breast screening clinic at Charing Cross Hospital, London.
If the trial is successful, women could have a simple blood test every year rather than breast screening.