British scientists develop virus that kills cancer cells

By Vanessa Chalmers Health Reporter For Mailonline

Scientists at Oxford University have developed a genetically modified virus that can kill cancer cells. 

The virus attacks both tumours and healthy cells, known as fibroblasts, that have been 'tricked' into protecting the cancer from the immune system.    

Any existing treatment that kills 'tricked' fibroblasts, may also destroy those in the bone marrow and skin.

Researchers said it is the first time cancer-associated fibroblasts within solid tumours have been specifically targeted in this way.

Scientists have developed a genetically modified virus that can kill cancer cells (stock)

Dr Kerry Fisher, from the University of Oxford's department of oncology, who led the research, said: 'Even when most of the cancer cells in a carcinoma are killed, fibroblasts can protect the residual cancer cells and help them to recover and flourish.

'Until now, there has not been any way to kill both cancer cells and the fibroblasts protecting them at the same time, without harming the rest of the body.

'Our new technique to simultaneously target the fibroblasts while killing cancer cells with the virus could be an important step towards reducing immune system suppression within carcinomas and should kick-start the normal immune process.'

The virus, called enadenotucirev, is already used in clinical trials for treating cancers that start in the pancreas, colon, lungs, breasts, ovaries or prostate.

The scientists attached a protein, called a bi-specific T-cell engager, to the virus. 

One end of the protein was targeted to bind to fibroblasts, while the other end specifically stuck to T-cells - a type of immune cell that is responsible for killing defective cells.

Binding the two together triggered the T-cells to kill fibroblasts that are attached to tumours.

Dr Nathan Richardson, head of molecular and cellular medicine at the Medical Research Council (MRC), which was involved in funding the study, said: 'Immunotherapy is emerging as an exciting new approach to treating cancers.

'This innovative viral delivery system, which targets both the cancer and surrounding protective tissue, could improve outcomes for patients whose cancers are resistant to current treatments. 

The team, whose findings were published in the journal Cancer Research, tested the therapy on mice and fresh human cancer samples collected from patients.

They also tested the virus on samples of healthy human bone marrow and found it did not cause toxicity.

If further safety testing is successful, it could be tested in cancer patients next year.

 Immunotherapy uses our immune system to fight cancer. It works by helping the immune system recognise and attack cancer cells. 

Our immune system works to protect the body against infection, illness and disease. It can also protect us from the development of cancer.

The immune system includes the lymph glands, spleen and white blood cells. Normally, it can spot and destroy faulty cells in the body, stopping cancer developing. But a cancer might develop when:

  • The immune system recognises cancer cells but it is not strong enough to kill the cancer cells
  • The cancer cells produce signals that stop the immune system from attacking it 
  • The cancer cells hide or escape from the immune system   

Immunotherapy is not yet as widely used as surgery, chemotherapy, and radiation therapy. Chemotherapy uses medication to kill cancer cells and radiotherapy means the use of radiation, usually X-rays, to treat illness.

Immunotherapy uses the natural power of your immune system to fight illnesses, and has been approved to treat people with many types of cancer.

There are different types of immunotherapy, some of which are also called targeted therapies or biological therapies.

 Monoclonal antibodies (MABs)   

Monoclonal antibodies are laboratory-produced molecules engineered to serve as substitute antibodies that can restore, enhance or mimic the immune system's attack on cancer cells. 

They are designed to bind to antigens that are generally more numerous on the surface of cancer cells than healthy cells. This process is called antibody dependent cell mediated cytotoxicity (ADCC).

Vaccines to treat cancer   

Normally, vaccines help to protect us from disease, and researchers are looking at whether vaccines can be used as a treatment to help the immune system to recognise and attack cancer cells.  

When you have the vaccine, it stimulates the immune system into action. The immune system makes antibodies that can recognise and attack the harmless versions of the disease. 

Once the body has made these antibodies it can recognise the disease if you come into contact with it again. So you’re protected from it.

Cytokines 

Cytokines are a group of proteins in the body that play an important part in boosting the immune system.

Interferon and interleukin are types of cytokines found in the body. Scientists have developed man made versions of these to treat some types of cancer.

 Adoptive cell transfer

Adoptive cell transfer changes the genes in a person’s white blood cells (T cells) to help them recognise and kill cancer cells. Changing the T cell in this way is called genetically engineering the T cell.

This treatment is only available as part of a clinical trial in the UK. An example of a type of adoptive cell transfer is CAR T-cell therapy.

 Source: Cancer Research UK