A COMBINATION of two immunotherapy drugs could be used to treat the most common form of bowel cancer, scientists say.
"Incredibly exciting" trials showed tumours had shrunk or remained stable in three out of five patients.
Botensilimab and balstilimab could "offer new hope" for those diagnosed with a type of cancer that has previously not responded to immunotherapy, researchers from Anglia Ruskin University said.
Both drugs work by triggering the body's immune system to attack cancer cells.
Describing the treatment as "potentially game changing", the team said it hopes authorities in the UK will be "able to move quickly" in approving its use.
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The researchers followed 101 people in the US who were diagnosed with microsatellite stable metastatic colorectal cancer (MSS mCRC) - the most common type of bowel cancer.
After six months, tumours were shown to shrink or remain stable in 61 per cent of the patients.
The most common side effects were diarrhoea and fatigue, the researchers said.
Until now, immunotherapy has only been shown to work on patients with another type of bowel cancer known as specific mismatch repair deficient (dMMR) tumours, which is rarer.
Close to 43,000 people are diagnosed with bowel cancer every year in the UK, with around 85 per cent classed as microsatellite stable (MSS).
More than 16,800 lose their lives annually, Cancer Research UK statistics show.
Justin Stebbing, professor of biomedical sciences at Anglia Ruskin University, said: "These results are incredibly exciting.
"Colorectal or bowel cancer is one of the most common forms of cancer worldwide.
"This is the first time there has been convincing evidence that immunotherapy can work in all forms of colorectal tumours, so this is potentially game changing.
"This is now progressing into later phase clinical trials and we hope the FDA in the United States approves its use very soon.
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"And because this is such an important area, affecting so many people, we hope authorities in the UK are also able to move quickly."
Dr Andrea Bullock, assistant professor in medicine at Beth Israel Deaconess Medical Centre in the US, added: "This study sheds light on the potential of the BOT/BAL combination to treat microsatellite stable metastatic colorectal cancer, the most common form of colorectal cancer which has historically not responded to immunotherapy.
"We hope our results will offer new hope for those diagnosed."
The research is published in the journal Nature Medicine.
Commenting on the study, Lisa Wilde, director of research, policy, and influencing at Bowel Cancer UK said: "This trial is still at a very early stage but does show exciting promise to extend much-needed treatment options for those whose cancer would previously have been resistant to immunotherapy.
"We will continue to follow with interest."
Bowel cancer is the fourth most common form of the disease in England.
Public awareness is on the up thanks to campaigners like Sun writer Dame Deborah James, who died from the disease in 2022 at just 40 years old.
