A platform for developing COLOrectal cancer PREVENTion therapies (COLO-PREVENT)
Professor Anne Thomas
University of Leicester
Cancer Research UK (CRUK)
Trial registration number
One way of preventing bowel cancer is to take drugs or dietary supplements (this is called therapeutic prevention). Most bowel cancers develop over many years from a polyp. A polyp is a growth on the bowel wall; also known as an adenoma. Several clinical trials have shown that aspirin use reduces the risk of developing polyps and the drug metformin, which is used in patients to treat diabetes, can also reduce the number of polyps. We want to test whether combining aspirin with metformin is able to prevent more bowel polyps forming than aspirin alone. We will test this in ‘high risk’ patients taking part in the National Bowel Cancer Screening Programme (BCSP), who have already had polyps removed at the bowel camera test (colonoscopy). We are also keen to understand whether the dietary agent resveratrol which is found in red grapes, reduces the number of polyps formed. For this part of the trial we will test two doses against a placebo tablet in a way that neither patients nor medical staff know what treatment is being given (double blind). Patients already taking aspirin or metformin will be able to take part in the resveratrol sub-trial.
The resveratrol sub-trial will be shorter and involve fewer patients than the main aspirin and metformin trial because we are just seeking an indication that resveratrol might protect against polyp recurrence; if the results are positive then they would provide justification to conduct a longer-term clinical trial in the future with the most effective dose of resveratrol.
Trial drugs will be given for 3 years in the main aspirin and metformin trial and 12 months in the resveratrol sub-trial, until patients have another planned BCSP colonoscopy, at which time the number and size of polyps will be measured. We will collect blood, faeces, urine and tiny samples of bowel tissue (biopsies) during the trial so that we can learn more about how the therapies work, as well as develop ‘biomarker’ tests to predict who will or won’t respond to each therapy. We are particularly interested in examining the effects of the therapies on gut bacteria, which will be analysed using faecal samples. The expected benefit is that the therapies will reduce the number of polyps and therefore potentially the risk of developing a bowel cancer. A major advantage of metformin, aspirin and resveratrol is that they are safe, have few side-effects and are already widely used by people with diabetes, heart and/or stroke disease or as a dietary supplement.
Number of participants
For the main trial we will randomise 862 participants and 477 for the sub-trial, with a total sample size for the two arms of 1339.
Main trial: Interventional, preventative, multi-centre, open-label, parallel, randomised control trial.
Signal seeking sub-trial: Interventional, preventative multi-centre, double-blinded, pharmacodynamic, pharmacokinetic, mechanistic, placebo, parallel, randomised controlled trial.