Review article: Biomarkers and personalised therapy in functional lower gastrointestinal disorders

Background Treatment of IBS and functional lower gastrointestinal disorders is still based predominantly on symptoms; biomarkers that reflect the mechanism or pathophysiology have been identified. Given the diverse mechanisms that result in the same clinical phenotype of IBS, it is hypothesised that identification of biomarkers may lead to individualisation of medical therapy. Aim To review the biomarkers that have been appraised in IBS. Methods A single author reviewed the published literature on biomarkers appraised in IBS. Results The current literature suggests that these biomarkers are insufficiently sensitive or specific to differentiate IBS from health or from other diseases causing similar symptoms, such as coeliac disease or inflammatory bowel disease. Most of the proposed biomarkers are not actionable, that is, they do not lead to an efficacious therapy based on the biological inference of the biomarker itself. However, among proposed biomarkers in IBS, some are actionable, as they specifically reflect a quantitative difference in a mediator of dysfunction or result in a quantifiable disturbance of function that can be specifically treated. Such biomarkers may potentially identify relevant subgroups that respond to specific therapy. The most promising actionable biomarkers are measurement of colonic transit (leading to treatments that reverse the abnormal transit) and measurements of bile acid diarrhoea to identify responders to bile acid sequestrants. Conclusions Therefore, although biomarkers are not ready for prime time as diagnostic tests in IBS, some biomarkers could identify subgroups of patients with IBS for inclusion in clinical trials that target specific dysfunctions. Such an approach may enhance treatment efficacy, and may ultimately help reduce costs in drug development and in the management of patients in clinical practice.