A new way of killing cancer cells by treating them as biological refuse has been discovered by scientists.
British researchers found that some new antibody drugs work by engaging the waste disposal system that exists in cells.
However, instead of ridding the cell of unwanted proteins or invading bacteria, the system goes into overdrive and kills the cell itself.
Until now scientists did not realise that antibody treatments which force tumour cells to die worked in this way.
The discovery could be further exploited to develop new and more effective drugs.
Nearly all animal cells contain lysosomes, small pockets containing powerful acidic digestive enzymes.
These act as the cell’s waste disposal system, by releasing their contents to destroy worn out cell components, ingested molecules or bacteria and viruses.
The Manchester and Southampton scientists found that several therapeutic antibodies caused cancer cell lysosomes to swell up and burst, killing the cell.
The researchers were investigating how antibody treatments work against leukaemia and lymphoma blood cancers.
A number of “monoclonal” antibody cancer drugs are now on the market. These are treatments that consist of many copies of just one (mono) type of antibody, cloned from a single human original. Two examples are Mabthera, used to treat leukaemia and non-Hodgkins lymphoma, and the breast cancer drug Herceptin.
Antibodies are in the front line of the body’s defences. They bind onto foreign invaders or harmful cells and either “flag them up” as immune system targets, or kill them directly.
Dr Mark Cragg, from the University of Southampton, said: “Our findings are significant and open up the possibility of applying the knowledge of how antibodies can be developed to trigger cell death and may enable us to design treatments for other cancers.”
The study, funded by the Association for International Cancer Research (AICR), was published today in the Journal of Clinical Investigation.
Dr Mark Matfield, from AICR, said: “The discovery of a new mechanism by which cancer cells kill themselves is an important step forward in cancer research. Killing the cancer cells is the basis of all successful cancer treatments.”
Medical charities welcomed the findings.
Dr David Grant, from Leukaemia Research said, “The discovery of the unique pathway used by antibody therapies to kill cancer cells has for the first time revealed why they are more effective than chemotherapy. This may lead to new treatments for patients with blood cancers who cannot be cured using conventional chemotherapy.”
Dr Lesley Walker, Cancer Research UK’s director of cancer information, said: “Although it’s at an early stage, this research provides valuable clues as to how monoclonal antibodies kill cancer cells, and could lead to more effective treatments for cancer in the future.”
Dr Ian Lewis, research manager at the cancer research charity Tenovus, said: “The beauty of this research is that it shows how the body’s own immune system can be mobilised to selectively destroy a patient’s own cancer.
“Normally the immune system struggles to tell the difference between a cancer cell and a healthy cell, but thanks to this research we now know how successful antibody treatments work and therefore how to apply it to the whole area of antibody therapy for cancer.”