American scientists say that provoking the body's immune system with the disease-causing bacteria may prove fundamental to treating cancer.
Experts at US vaccine company Advaxis say that their proposition is based on a study wherein they found evidence suggesting that deliberately infecting people with the bacteria that cause listeriosis could increase their ability to destroy tumours.
They say that their main objective is to kick-start the body's immune system by "provoking" it with the bacteria, which are modified to trigger an attack on the cancer.
The researchers said that they chose Listeria monocytogenes because of its ability to stow away in immune cells called antigen-presenting cells (APCs), which prime the rest of the immune system to attack a given strain of microbe by showing fragments of antigen from that microbe to the appropriate cells.
For the study, the bacterium was modified so that it was no longer harmful and, once inside the APC, it would secrete fragments of HPV-E7, a molecule found on the surface of cervical cancer cells.
The researchers said that by presenting HPV-E7 to other immune cells, the APCs would then prime them to attack the cancer.
Telling about the results of their study, the researchers revealed that four of the 13 women with advanced cervical cancer, who participated in the preliminary trial, responded to the bacteria injection.
While tumours in three women shrank by 20 per cent, one is still tumour-free more than two years after the treatment.
The researchers have revealed that seven of the 13 participants have died from the cancer, reports New Scientist.
Advaxis now plans to conduct a trial on 180 patients with less advanced cervical cancer.
John Stanford of University College London, whose team has had recent success treating cancer patients with dead Mycobacterium vaccae, believes that Advaxis may need to administer booster doses to sustain the therapeutic effect.