Volatile organic metabolites to predict clinical response in patients with inflammatory bowel diseases treated with biological therapy

BACKGROUND: Variations in faecal volatile organic metabolites (VOMs) are increasingly thought to be indicative of digestive disorders. There are no studies in the literature that evaluated VOMs for inflammatory bowel disease (IBD) treatment response prediction. The assessment of the VOMs’ capacity to predict clinical response after a year of adalimumab or vedolizumab therapy was the main goal of our investigation. VOM and IBD clinical characteristic correlations were among the secondary outcomes. METHODS: We sequentially included IBD patients who had indications for biologic treatment as part of a prospective research. RESULTS: We collected fifty IBD patients, and we used gas chromatography/mass spectrometry (GC/MS) to study their feces. Adalimumab was used to treat 31 patients, while vedolizumab was used to treat 19 individuals. After a year of treatment, pre-biologics methyl butyrate could predict clinical response (AUC = 0.68, 95%CI = 0.53-0.81, P=0.02). Age, the length of the disease, gender, or smoking habit had no effect on VOMs. Two VOMs, octenol and, specifically, methyl indole, correlated with greater levels of inflammation markers (CRP and calprotectin, respectively) and were able to differentiate between ulcerative colitis (UC) and Crohn’s disease (CD) (AUC = 0.72 and 0.85, respectively). On the other hand, methylbutanal was associated with CD and specifically with ileal location (P=0.01). With an accuracy at least comparable to calprotectin, methyl butanoate could differentiate between active clinical illness and remission (AUC = 0.69 and 0.62, respectively). CONCLUSIONS: Using VOMs to characterize the intestinal metabolome appears to be a viable way to better understand IBD.