Inflammatory bowel disease in 2024 and beyond

In 1987, Professor Roy Pounder launched Alimentary Pharmacology and Therapeutics and in that very issue, he was the senior author on a retrospective study of cyclosporin for the management of Crohn's disease.¹ Since that time, the incidence and prevalence of inflammatory bowel disease (IBD) has risen exponentially, reaching all corners of the globe and all ethnicities. Alimentary Pharmacology and Therapeutics has provided gastroenterologists with a broad spectrum of clinically relevant journal articles for 37 years through 60 volumes of high-quality publications. The breadth of these is reflected in the range of journal articles that we have assembled for this special IBD edition of Alimentary Pharmacology and Therapeutics. Looking back through the journal listings, this is the ninth special edition focused on IBD, but the first for 16 years. As associate editors, we are proud of this collection of cutting-edge reviews written by an exceptional group of IBD experts, all with strong connections to the journal.

In 1987, the possibility of disease prevention would have seemed fanciful. However, as we learn from prevention trials in type 1 diabetes mellitus and rheumatoid arthritis, several critical steps have emerged that need to be followed if we are to advance prediction and prevention. Bronze et al. present a road map for how we can navigate a journey to IBD prevention via validated predictive biomarkers to develop a multi-dimensional predictive tool. While science advances, we must also be aware of ethical issues including the preferences of first-degree relatives of those with IBD and how we use predictive information. Finally, bringing together expertise and patients in high-risk clinics should enable appropriate prevention trials.²

The question as to what comprises severe IBD has been one that has long vexed clinicians and patients with IBD. Over time, interest has moved from symptoms to both markers of inflammation (endoscopic, histologic and biomarkers) and a more holistic view (quality of life, disability and psychosocial health). Swaminathan et al. walk us through these concepts before defining disease severity and how this includes all these facets of IBD. Understanding how these interact enables clinicians to focus on specific therapeutic targets and improve outcomes for individuals with IBD.³

Understanding the wider burden of disease includes a focus on the gut–brain axis in patients with IBD. Riggott et al. describe the bi-directional relationship between psychological wellbeing and adverse longitudinal disease activity outcomes, and the high prevalence of irritable bowel syndrome-type symptoms. Treatments that target the gut–brain axis include behavioural treatments, neuromodulators and dietary interventions. Proactive management of psychological health is a critical component in the overall disease management of IBD patients.⁴

In their review of evidence-based dietary management of IBD, Gibson et al. present the four pillars of dietary management. This paradigm provides an excellent approach to dietary strategies for patients with IBD. Firstly, nutritional status should be optimized through accurate body composition measurement and attention to sarcopenia and visceral adiposity. Secondly, exclusive enteral nutrition and the Crohn's disease exclusion diet with partial enteral nutrition are effective at reducing intestinal inflammation in patients with Crohn's disease. Thirdly, there are a range of dietary approaches to managing non-inflammatory symptoms in patients with IBD. Finally, following a healthy diet is fundamental to the general health of patients with IBD. There must also be a clear focus on the risks of nutritional inadequacy and maladaptive eating behaviours.⁵

For more than 25 years we have used biologic drugs for the treatment of IBD. Over time the number of these has increased with more targets now in scope, and our ability to use each of these drugs smarter has led to benefits for patients. Chaemsupaphan et al. describe how biologic drugs can be optimized using therapeutic drug monitoring and measurement of neutralizing antibodies. Optimizing treatment effect increases the likelihood of clinical and deeper levels of remission in a treat-to-target paradigm. While guidelines of when to escalate and when to switch agents have emerged for the use of anti-TNF drugs, non-TNF inhibitors demonstrate less robust exposure-response relationships and therapeutic drug monitoring may not prove as beneficial.⁶

In the final paper in this special edition, Noor et al. provide a pragmatic guide for clinicians on recently approved and emerging therapies and address key challenges of optimal sequencing and timing of treatment. For many of these new therapies, further data from long term extension studies, real world studies and head-to-head trials are needed to inform long term safety and sequencing strategies.⁷

We would like to thank the 24 authors from eight countries for contributing to this special edition of Alimentary Pharmacology and Therapeutics. We hope that you will enjoy reading these thoughtful papers and other work published in Alimentary Pharmacology and Therapeutics in the future.

Richard B. Gearry: Conceptualization; writing – original draft; writing – review and editing; visualization; project administration. Cynthia H. Seow: Conceptualization; writing – review and editing; project administration. Sreedhar Subramanian: Conceptualization; writing – review and editing; visualization; project administration.

R.B.G. has received research grants, served on advisory boards or received honoraria for educational activities for Janssen, AbbVie and Zespri (unrelated to this manuscript). C.H.S has received research grants, served on advisory boards or received honoraria from Janssen, AbbVie, Takeda, Lilly, Ferring, Shire, Pfizer, Sandoz, Pharmascience, Fresenius Kabi and Amgen, Bristol Myers Squibb, ACHRI, CIHR, Calgary Health Trust, New South Wales Government Health. S.S. has received research grants, served on advisory boards or received honoraria from MSD, Ipsen, AbbVie, Dr. Falk pharmaceuticals, Takeda, Janssen, Celltrion and Vifor pharmacceuticals.