The dark side of the immune

Some types of immune response are more likely to contribute to tumour growth than to help fight cancer, claims a leading Cancer Research UK scientist today.

Speaking at Cancer Research UK’s first annual conference in Kenilworth today, Professor Frances Balkwill will present evidence that while genetic damage lights the fire of cancer, inflammation caused by immune reaction can provide the fuel to feed the flames.

And she believes a better understanding of how immune or inflammatory cells work will help to develop new anti-cancer drugs.

Prof Balkwill has focused on ovarian cancer in order to study the way that immune responses can fuel the later stages of cancer development.

She has discovered that, far from assisting in fighting cancer, some of the molecules and cells involved in inflammation could be providing exactly the environment it needs to spread and grow.

For instance she has found that the inflammatory molecule TNFa, traditionally believed to have anti-cancer activity, is made by tumours and helps them grow and spread.

Prof Balkwill says: “A patient with advanced ovarian cancer may have millions of extra cells all working together and fuelling each other. Many of these will not be cancer cells; tumours need other cells and the molecule TNFa helps them to achieve this.”

TNFa triggers various chemical signals that persuade other cells to join the tumour. These cells are helpful in the wound healing process where they repair tissue damage.

However when these same cells are recruited into a tumour, they seem to provide stimuli that encourage growth.

The secretion of TNFa also changes the structure of the surrounding tissue, making it easier for cancer to spread outwards.

The use of TNFa antagonists helps patients with rheumatoid arthritis and Cancer Research UK is beginning trials to see whether a similar approach can be employed in the treatment of ovarian cancer.

Prof Balkwill says: “We are looking at existing drugs involved in treating inflammatory diseases and hoping they will act in the same way on certain cancers.”

Sir Paul Nurse, Chief Executive of Cancer Research UK says: “Understanding the environment a tumour needs for its progression is a vital step in fighting cancer. Some inflammatory molecules seem to be a vital part of the fuel for tumours and drugs to dampen that fuel could bring important benefits for patients.”

ENDS