SALMONELLA is normally associated with violent food poisoning.
But now scientists believe the horror bug could be manipulated to help fight bowel cancer.
Experts have long known that salmonella could help beat cancer but when used in therapies it has not been as effective as hoped.
This is because, while it does suppress tumour cell growth, it also suppresses a part of our immune system which is essential to fight tumours.
New research on mice pinpointed the mechanism that causes the immune system to be suppressed and offers a solution.
As part of the study, published on Tuesday in the journal EMBO Molecular Medicine, experts looked at the response of T cells to a specially engineered safe form of salmonella in mice with bowel cancer.
Scientists from Glasgow and Birmingham found salmonella stopped T cells from fighting cancer cells.
This was down to the bacteria depleting an amino acid called asparagine.
The researchers believe that salmonella could be further engineered to work alongside the immune system so T cells can attack cancer cells alongside the bacteria.
It is hoped the discovery can overcome the problem and help “unleash the full potential” of using salmonella to fight cancer.
Lead author, Dr Alastair Copland, from the University of Birmingham, said: “Bacterial therapies are an exciting way to treat cancer by essentially starving tumours of vital nutrients.
“One longstanding mystery has been why T cells, which are key to fighting cancer, don’t function optimally during this treatment.
“Now, we’ve identified the protein responsible for this, and pinpointed an exciting genetic target that could help us unleash the full potential of this therapy.
“It’s particularly rewarding to turn a disease-causing bug like salmonella into one that combats cancer.”
Salmonella can cause food poisoning and can be present in the guts of many animals, including chickens, cows and pigs.
The bacteria can contaminate food like eggs, chicken and pork, as well as fruits and vegetables that have been in contact with livestock or manure.
Symptoms of salmonella infection include diarrhoea, stomach cramps, nausea, vomiting and fever, and usually develop within 12 to 72 hours and last from four to seven days.
IT’S a worrying fact that more than half of us will get cancer in our lifetime.
Each year around 385,000 people are diagnosed and 167,000 lives are lost to the disease in the UK . . . and experts have warned of an alarming new surge in the young.
But, in the face of rising cases, there is good news — the future of cancer care looks brighter.
Personalised medicine
Perhaps the most exciting new avenue of research is tailoring medicine to treat a patient’s cancer based on their own tumour’s genetic make-up.
Professor Lawrence Young, an oncologist who has been working in cancer research for 40 years, says: “We’ve learnt that by profiling the genetics, you almost get a barcode for an individual’s cancer.
“Just because somebody’s got the same stage and grade of cancer, doesn’t mean it should be treated the same, or with a particular combination of drugs.”
The NHS announced in May that it would trial personalised cancer vaccines designed by biotech giants BioNTech and Genentech.
Some 10,000 patients in England are set to get their very own disease-busting jab by 2030, through the NHS Cancer Vaccine Launch Pad.
Immunotherapy
Dubbed the “biggest breakthrough since chemo”, immunotherapy harnesses the power of the immune system to fight cancer.
Antibodies seek out and mark the diseased cells for destruction but spare surrounding healthy tissue, unlike chemotherapy or radiotherapy.
Prof Young says: “We’ve known for 100 years the body tries to fight cancer with the immune system but it doesn’t really work.
“Cancer cleverly learns how to get around the immune response. It can switch off the way the immune system recognises it – but these antibodies can switch it back on again.
“Antibodies are effective alone, but where they are most effective is in combination with another type of immunotherapy.”
Keytruda (pembrolizumab) brings cancer cells out from hiding.
It has been approved for treating several cancers on the NHS, including melanoma, cervical, breast and lung cancer. But its use could be extended to bowel cancer.
Targeted cancer drugs
These work more precisely to stop cancer cells from dividing and growing, while limiting damage to healthy cells – and their uses are expanding.
Prof Young says: “This is targeting the machinery of the genetic mutations that drive cancer.
“Some are targets we’ve known about for years but were difficult, until recently, to develop drugs for.
“The normal growth of our cells is controlled by switches which become mutated and permanently switched on in cancer cells.
“Now, after years of research, we have targeted drugs which can switch off these growth signals.”
Kinase inhibitors are targeted drugs – small molecules that stop certain enzymes involved in cancer growth.
Lorlatinib, branded as Lorviqua, is used for a handful of patients with ALK-positive non-small cell lung cancer.
But after “groundbreaking” results in May, campaigners hope it will become a lifeline for the 350 people in the UK who are diagnosed with this type of cancer each year.
Blood tests
Early diagnosis is still the best weapon against cancer and its devastating impacts.
Blood tests are becoming increasingly sensitive in spotting the disease.
Prof Young says: “Current blood tests aren’t that great. For example, we measure the proteins PSA, for prostate cancer, or CEA, for ovarian cancer, but they’re not very specific.
“We want to do our best to cure cancer with early diagnosis, and with these interesting blood tests it might be possible to identify cancer early and remove it before we get too far.”
These new blood tests can “identify minuscule amounts of DNA shed from tumour cells into the blood”, Prof Young says.
The NHS has been trialling the Galleri blood test in England and Wales, using 140,000 volunteers so far, and will continue until 2026.
Lead researcher Dr Kendle Maslowski, from the University of Glasgow, added: “We know attenuated salmonella and other bacteria have the power to tackle cancer, however until now it was not known why it was not proving as effective as it should be.
“Our research has discovered that it is an amino acid called asparagine that the bacteria attacks which is essential for T cells to be activated.
“We believe this knowledge could enable bacteria to be engineered not to attack asparagine allowing the T cells to act against the tumour cells leading to new effective treatments for cancer.”
There are more than 44,000 new cases of bowel cancer each year in the UK, making it the fourth most common form of the disease.
Dr Catherine Elliott, director of research at the Cancer Research UK, which funded the study said: “Bacterial therapies have not become mainstream despite the massive strides we are making with immunotherapies which use our own bodies’ immune system to attack cancer.
“But the power of bacteria has long been acknowledged as likely to hold significant potential to tackle disease.
“This exciting development from the Cancer Research UK Scotland Institute could lead to more effective treatments for patients with colorectal, and other cancers in future, providing hope for patients.”
