Medicine (St Vincent's) - Theses

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Type: PhD thesis × Subject: inflammatory bowel disease × Subject: Crohn's disease × Author: Ding, Nik Sheng ×

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    Predicting response to anti-TNF therapy in Crohn's disease: clinical and metabolic studies
    Ding, Nik Sheng ( 2018)
    Crohn’s disease is a chronic, disabling inflammatory condition that affects the gastrointestinal tract that is associated with significant morbidity. Up to 80 percent of patients require surgery at some point in their lives. A third of patients require surgery within five year of diagnosis even in the era of biologic therapy. Ant- Tumour Necrosis Factor alpha (Anti-TNF) therapies form the backbone of drug therapy in patients with moderate to severe Crohn’s disease and remain the most effective biologic drugs available. There are currently three classes of biological drugs available on the Pharmaceutical Benefits Scheme (PBS) for Australians with many more under development. Up to thirty percent of patients fail to have an adequate response to anti-TNF therapy and loss of response occurs at a rate of ten percent per year. There are at present no highly sensitive biomarkers of response to anti-TNF therapies. Without biomarkers to assist with selecting the most effective biologic for a particular patient, there is a risk of exposing patients to ineffective drug therapies with unnecessary side-effects and costs. This thesis comprises a range of clinical and scientific studies that seek to identify predictors of loss of response to anti-TNF therapies in Crohn’s disease. Two types of loss of response have been identified: Primary nonresponse (PNR), is defined as a lack of response to the initial drug therapy as determined at 12 weeks post induction, and Secondary Loss of Response (SLOR) is defined as the loss of response after the patient has had an initial response to the drug. Based on the clinical observation that patients with altered body composition and those with strictures have a variable to response to anti-TNF therapy, we sought to identify whether there were specific clinical, endoscopic, histologic and biochemical parameters that correlated with response to anti-TNF therapy amongst patients from whom longitudinal body composition and endoscopic data had been collected. A prospective cohort study of patients who had been newly started on anti-TNF therapies was also undertaken. In this cohort samples of urine, blood and faeces were taken prior to anti-TNF therapy delivery (baseline) and then at 3 monthly intervals thereafter. A combination of bioinformatic analyses and novel techniques evaluating the metabolome were applied to the cohort, in order to find clinical factors and biomarkers that might correlate with therapeutic response to anti-TNF therapy. This series of studies presented in this thesis on clinical and metabolic predictors of outcomes in patients receiving anti-TNF therapy for Crohn’s disease reveals new insights into the pathophysiology of Crohn’s disease and has identified biomarkers for the prediction of therapeutic response – thereby helping to come a step closer towards the ultimate goal of precision medicine.