Regular use of aspirin may reduce the incidence of colorectal cancer (CRC). However, it is unclear through which mechanism aspirin exerts its effect, in whom it decreases CRC risk and in whom it causes side effects. Recently, the imbalanced gut microbiome was linked to inflammation and CRC risk. The main hypothesis for this study is that aspirin may decrease CRC risk via targeting the gut microbiome. The study will be a randomized placebo-controlled double-blinded design, recruiting 50 healthy subjects, 50-75 years old, from the PRospective Evaluation of SEPTin 9 (PRESEPT) cohort living in the greater Twin Cities area, who will receive either aspirin or placebo for 6 weeks.
The pilot study will evaluate the feasibility of conducting a large randomized trial and estimate the effects of aspirin on the gut microbiome. The study will recruit 50 healthy subjects, 50-75 years old, from the PRospective Evaluation of SEPTin 9 (PRESEPT) cohort living in the greater Twin Cities area. The Primary Aim is to estimate the impact of a 3- and 6-week intake of once daily 325 mg aspirin on the composition of the gut microbiome using a randomized placebo-controlled double-blinded design, i.e. examine the change of microbiome over time within and between the subjects. The hypothesis for this aim is that in the aspirin arm versus the placebo arm, gut microbiome composition will shift towards a lower proportion of pro-inflammatory, CRC-predisposing bacteria (e.g. Fusobacteria) and higher proportion of anti-inflammatory, CRC-protective bacteria (e.g. butyrate-producing bacteria). The Secondary Aims are to examine the correlation between the aspirin-related changes in microbiome profile with the levels of circulating inflammatory biomarkers in urine and plasma. Within-individual and between-arm differences in microbiome composition will be compared after 3 and 6 weeks of aspirin intake. Also, the microbiome composition will be compared after 3-week and 6-week wash-out periods to test whether these periods are sufficient to restore gut microbiome composition to a pre-treatment level. This study will inform future crossover randomized studies focusing on CRC preventive interventions that will enable clinicians to identify optimal candidates for aspirin therapy for the purposes of CRC prevention using this accessible and cheap drug.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
Epidemiology Clinical Research Center
Minneapolis, Minnesota, United States
Composition of the gut microbiome
Fecal microbial diversity and the prevalence of specific taxa associated with colorectal cancer (e.g. Fusobacteria, butyrate producing bacteria) will be estimated at each time point. The aspirin-related changes in the prevalence of each taxon will be assessed individually and also combined into a microbiome index (the abundance of protective taxa will be included as a negative value).
Time frame: 5 times within 12 weeks
Urinary and blood inflammatory biomarkers
Each inflammatory biomarker (e.g. urinary metabolite of Prostaglandin E2 (PGE2)) will be measured before and after treatment with aspirin. Changes in inflammatory markers will be correlated to changes in the microbial diversity and the microbiome index.
Time frame: 2 times within 6 weeks
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BASIC_SCIENCE
Masking
QUADRUPLE
Enrollment
50