Landscape of new drugs and targets in inflammatory bowel disease

DAMP-ing IBD: Extinguish the Fire and Prevent Smoldering

In inflammatory bowel diseases (IBD), the most promising therapies targeting cytokines or immune cell trafficking demonstrate around 40% efficacy. As IBD is a multifactorial inflammation of the intestinal tract, a single-target approach is unlikely to solve this problem, necessitating an alternative strategy that addresses its variability. One approach often overlooked by the pharmaceutically driven therapeutic options is to address the impact of environmental factors. This is somewhat surprising considering that IBD is increasingly viewed as a condition heavily influenced by such factors, including diet, stress, and environmental pollution-often referred to as the "Western lifestyle". In IBD, intestinal responses result from a complex interplay among the genetic background of the patient, molecules, cells, and the local inflammatory microenvironment where danger- and microbe-associated molecular patterns (D/MAMPs) provide an adjuvant-rich environment. Through activating DAMP receptors, this array of pro-inflammatory factors can stimulate, for example, the NLRP3 inflammasome-a major amplifier of the inflammatory response in IBD, and various immune cells via non-specific bystander activation of myeloid cells (e.g., macrophages) and lymphocytes (e.g., tissue-resident memory T cells). Current single-target biological treatment approaches can dampen the immune response, but without reducing exposure to environmental factors of IBD, e.g., by changing diet (reducing ultra-processed foods), the adjuvant-rich landscape is never resolved and continues to drive intestinal mucosal dysregulation. Thus, such treatment approaches are not enough to put out the inflammatory fire. The resultant smoldering, low-grade inflammation diminishes physiological resilience of the intestinal (micro)environment, perpetuating the state of chronic disease. Therefore, our hypothesis posits that successful interventions for IBD must address the complexity of the disease by simultaneously targeting all modifiable aspects: innate immunity cytokines and microbiota, adaptive immunity cells and cytokines, and factors that relate to the (micro)environment. Thus the disease can be comprehensively treated across the nano-, meso-, and microscales, rather than with a focus on single targets. A broader perspective on IBD treatment that also includes options to adapt the DAMPing (micro)environment is warranted.

Evolution of Eligibility Criteria in Inflammatory Bowel Disease Clinical Trials: A Clinical Trial Databank Analysis

BACKGROUND

Eligibility criteria in clinical trials have been criticised for being overly restrictive without clinical justification.

OBJECTIVE

We aimed to investigate the types, evolution, and current status of eligibility criteria in clinical trials for inflammatory bowel diseases (IBD).

METHODS

We performed a clinical trial databank search on clinicaltrials.gov, and included all Phase 3 placebo-controlled randomised-controlled trials (RCTs) investigating biologics or small molecules as induction therapy for moderate-to-severe Crohn's disease (CD) and ulcerative colitis (UC). Eligibility criteria were analysed both quantitatively and qualitatively.

RESULTS

Fifty-nine RCTs were identified between the year 2000 and 2022 (30 for CD and 29 for UC). The median (interquartile range) number of eligibility criteria was 44 (38-49), and did not significantly change over the studied time period (p = 0.26). Qualitative analysis showed that common patient populations, such as older patients, therapy refractory patients, patients with comorbidities, prior malignancies, unclassified IBD type, ulcerative proctitis, stricturing and fistulizing CD, as well as patients with an ostomy, were often excluded. Heterogeneity in eligibility criteria across the different IBD clinical trials was found, such as for disease activity measurement, dosage of concomitant medication, wash-out period of advanced therapies, and laboratory tests.

CONCLUSION

The median number of eligibility criteria for IBD RCTs did not significantly change over time. The eligibility criteria are however restrictive and complex, limiting the generalisability of efficacy and safety outcomes in daily practice when drugs are approved. Future research is needed to investigate the impact of broadening eligibility criteria to better encompass real-world practice.

Development and Assessment of a Novel Ulcerative Colitis-Specific Quality of Life Questionnaire: A Prospective, Multi-Institutional Study

PURPOSE

Interest in the quality of life (QoL) of patients with inflammatory bowel disease (IBD) has recently increased. Although measurement tools have been devised for IBD in general, there is no specific tool for measuring the QoL of patients with ulcerative colitis (UC). Therefore, we developed a QoL questionnaire specifically for patients with UC.

MATERIALS AND METHODS

The Korean Ulcerative Colitis-Specific Questionnaire (K-UCSQ) was developed through item generation, raw-scale construction, focus group meetings, and multi-center field tests. Two hundred patients with UC were recruited for a field test of the K-UCSQ, and subsequent responses to the Inflammatory Bowel Disease Questionnaire (IBDQ) were also obtained. After performing factor analyses to ensure construct validity, the K-UCSQ was finalized as a four-domain, 28-item questionnaire. Subsequent analyses evaluated the reliability of the K-UCSQ in terms of Cronbach's alpha, concurrent validity in comparison with the pre-established IBDQ, and predictive validity of the area under the ROC curve (AUC) for clinically relevant QoL outcomes.

RESULTS

A Cronbach's alpha of 0.94 showed excellent reliability. Furthermore, correlation analyses demonstrated the concurrent validity of the K-UCSQ in comparison with the IBDQ. The K-UCSQ also showed high validity in predicting the perceived overall health (AUC of 0.812 vs. 0.797 using the IBDQ) and past 2-week QoL (AUC of 0.864 vs. 0.859 using the IBDQ).

CONCLUSION

The newly developed K-UCSQ is concise, bathroom problem-emphasizing, and UC-specific, suggesting that it could be a valid and reliable UC-specific instrument for QoL measurement.

Harms with placebo in trials of biological therapies and small molecules as induction therapy in inflammatory bowel disease: a systematic review and meta-analysis

BACKGROUND

Randomised placebo-controlled trials are the gold standard to assess novel drugs in ulcerative colitis and Crohn's disease. However, there might be risks associated with receiving placebo. We aimed to examine the harms associated with receiving placebo in trials of licensed biologics and small molecules for the induction of remission in ulcerative colitis and luminal Crohn's disease in a meta-analysis.

METHODS

We performed a systematic review and meta-analysis. We searched MEDLINE, Embase, Embase Classic, and the Cochrane Central Register of Controlled Trials from database inception to May 30, 2024, for randomised placebo-controlled trials of licensed biologics and small molecules for induction of remission in adults (≥18 years) with moderately to severely active ulcerative colitis or luminal Crohn's disease reporting data on adverse events over a minimum treatment period of 4 weeks. There were no prespecified study exclusion criteria. We extracted summary data and pooled data using a random-effects model for any treatment-emergent adverse event, any drug-related adverse event, infection, worsening of inflammatory bowel disease (IBD) activity, withdrawal due to adverse events, serious adverse events, serious infection, serious worsening of IBD activity, or venous thromboembolic events (VTEs), reporting relative risks (RRs) with 95% CIs. The protocol for this meta-analysis was registered with PROSPERO (CRD42024527341).

FINDINGS

The search identified 10 826 citations, of which 47 trials including 20 987 patients (14 267 [68·0%] receiving active drug and 6720 [32·0%] receiving placebo) were eligible. The risk of any treatment-emergent adverse event was no different with active drug than with placebo (7660/14 267 [53·7%] patients on active drug vs 3758/6720 [55·9%] on placebo; RR 0·97, 95% CI 0·94-1·00; I2 =36%). However, the risks of worsening of IBD activity (563/13 473 [4·2%] vs 530/6252 [8·5%]; 0·48, 0·40-0·59; I2 =54%), withdrawal due to adverse event (401/13 363 [3·0%] vs 299/6267 [4·8%]; 0·62, 0·48-0·79; I2 =46%), serious adverse event (682/14 267 [4·8%] vs 483/6720 [7·2%]; 0·69, 0·59-0·80; I2 =30%), serious infection (140/14 194 [1·0%] vs 91/6647 [1·4%]; 0·67, 0·50-0·89; I2 =0%), serious worsening of IBD activity (187/11 271 [1·7%] vs 189/5056 [3·7%]; 0·45, 0·34-0·60; I2 =27%), or VTEs (13/7542 [0·2%] vs 12/2981 [0·4%]; 0·45, 0·21-0·94; I2 =0%) were all significantly lower with active drug than placebo. Numbers needed to treat with active drug to avoid these potentially serious adverse events ranged from 23 for worsening of IBD activity to 452 for VTEs. 27 randomised controlled trials were judged as low risk of bias across all domains.

INTERPRETATION

Patients with moderately to severely active IBD receiving placebo are more likely to experience significant worsening of IBD activity and some serious adverse events, which might relate to a reduction in risk of these events with active drug. Patients should be counselled about these potential harms, and alternative trial designs to mitigate these harms should be considered.

FUNDING

None.

Chronic Kidney Disease in Inflammatory Bowel Disease: a Systematic Review and Meta-analysis

Inflammatory bowel disease [IBD] is associated with various immune-mediated disorders including spondylarthritis, pyoderma gangrenosum, primary sclerosing cholangitis, and uveitis. Chronic kidney disease [CKD] is defined by a reduction in kidney function (estimated glomerular filtration rate [eGFR] less than 60 ml/min/1.73m2] and/or damage markers that are present for at least 3 months, regardless of the aetiology. Case reports and cohort studies suggest that IBD is associated with CKD. The extent and magnitude of a potential association is unknown. A comprehensive search was conducted in EMBASE, MEDLINE, Web of Science, the Cochrane database, and SCOPUS. Two separate reviewers were involved in the process of article selection and evaluation. Odds ratios were calculated in those papers with a comparison between an IBD population and a non-IBD control population, the Mantel Haenszel test was employed, using a random effect model. The systematic review was registered in PROSPERO [RD42023381927]. A total of 54 articles was included in the systematic review. Of these, eight articles included data on prevalence of CKD in IBD patients [n = 102 230] vs healthy populations [n = 762 430]. Of these, diagnosis of CKD was based on International Classification of Diseases [ICD] codes in five studies vs on eGFR in three studies. The overall odds ratio of developing CKD in the IBD population is 1.59, [95% CI 1.31-1.93], without any difference between studies using diagnostic coding (odds ratio [OR] 1.70, 95% CI 1.33-2.19] vs diagnosis based on eGFR [OR 1.36, 95% CI 1.33-1.64]. IBD is associated with a clinically meaningful increased CKD prevalence. We provide recommendations on diagnostic evaluation, as well as suggestions for future research.

Rates of Adverse Events in Patients With Ulcerative Colitis Undergoing Colectomy During Treatment With Tofacitinib vs Biologics: A Multicenter Observational Study

INTRODUCTION

Patients with ulcerative colitis (UC) receiving immunosuppressive drugs are at substantial risk of colectomy. We aimed to assess the risk of postoperative complications of tofacitinib exposure before colectomy in comparison with biologics.

METHODS

A multicenter, retrospective, observational study was conducted in patients with UC who underwent total colectomy for medically refractory disease, exposed to tofacitinib or a biologic before surgery. Primary outcome was the occurrence of any complication within 30 (early) and 90 (late) days after surgery. Secondary outcomes were the occurrence of infections, sepsis, surgical site complications, venous thromboembolic events (VTE), hospital readmissions, and redo surgery within the same timepoints.

RESULTS

Three hundred one patients (64 tofacitinib, 162 anti-tumor necrosis factor-α agents, 54 vedolizumab, and 21 ustekinumab) were included. No significant differences were reported in any outcome, except for a higher rate of early VTE with anti-tumor necrosis factor-α agents ( P = 0.047) and of late VTE with vedolizumab ( P = 0.03). In the multivariate analysis, drug class was not associated with a higher risk of any early and late complications. Urgent colectomy increased the risk of any early (odds ratio [OR] 1.92, 95% confidence interval [CI] 1.06-3.48) complications, early hospital readmission (OR 4.79, 95% CI 1.12-20.58), and early redo surgery (OR 7.49, 95% CI 1.17-47.85). A high steroid dose increased the risk of any early complications (OR 1.96, 95% CI 1.08-3.57), early surgical site complications (OR 2.03, 95% CI 1.01-4.09), and early redo surgery (OR 7.52, 95% CI 1.42-39.82). Laparoscopic surgery decreased the risk of any early complications (OR 0.54, 95% CI 0.29-1.00), early infections (OR 0.39, 95% CI 0.18-0.85), and late hospital readmissions (OR 0.34, 95% CI 0.12-1.00).

DISCUSSION

Preoperative tofacitinib treatment demonstrated a postoperative safety profile comparable with biologics in patients with UC undergoing colectomy.

Deciphering Microbial Composition in Patients with Inflammatory Bowel Disease: Implications for Therapeutic Response to Biologic Agents

Growing evidence suggests that alterations in the gut microbiome impact the development of inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis (UC). Although IBD often requires the use of immunosuppressant drugs and biologic therapies to facilitate clinical remission and mucosal healing, some patients do not benefit from these drugs, and the reasons for this remain poorly understood. Despite advancements, there is still a need to develop biomarkers to help predict prognosis and guide treatment decisions. The aim of this study was to investigate the gut microbiome of IBD patients using biologics to identify microbial signatures associated with responses, following standard accepted criteria. Microbiomes in 66 stool samples from 39 IBD patients, comprising 20 CD and 19 UC patients starting biologic therapies, and 29 samples from healthy controls (HCs) were prospectively analyzed via NGS and an ensemble of metagenomics analysis tools. At baseline, differences were observed in alpha and beta metrics among patients with CD, UC and HC, as well as between the CD and UC groups. The degree of dysbiosis was more pronounced in CD patients, and those with dysbiosis exhibited a limited response to biological drugs. Pairwise differential abundance analyses revealed an increasing trend in the abundance of an unannotated genus from the Clostridiales order, Gemmiger genus and an unannotated genus from the Rikenellaceae family, which were consistently identified in greater abundance in HC. The Clostridium genus was more abundant in CD patients. At baseline, a greater abundance of the Odoribacter and Ruminococcus genera was found in IBD patients who responded to biologics at 14 weeks, whereas a genus identified as SMB53 was more enriched at 52 weeks. The Collinsella genus showed a higher prevalence among non-responder IBD patients. Additionally, a greater abundance of an unclassified genus from the Barnesiellaceae family and one from Lachnospiraceae was observed in IBD patients responding to Vedolizumab at 14 weeks. Our analyses showed global microbial diversity, mainly in CD. This indicated the absence or depletion of key taxa responsible for producing short-chain fatty acids (SCFAs). We also identified an abundance of pathobiont microbes in IBD patients at baseline, particularly in non-responders to biologic therapies. Furthermore, specific bacteria-producing SCFAs were abundant in patients responding to biologics and in those responding to Vedolizumab.

Analysis of Clinical Trial Screen Failures in Inflammatory Bowel Diseases [IBD]: Real World Results from the International Organization for the study of IBD

BACKGROUND

Recruitment for randomized controlled trials [RCTs] in inflammatory bowel diseases [IBD] has substantially dropped over time. This study aimed to assess reasons why IBD patients are not included in sponsored multicentre phase IIb-III RCTs.

METHODS

All IOIBD members [n = 58] were invited to participate. We divided barriers to participation as follows: [1] reasons patients with active IBD were not deemed appropriate for an RCT; [2] reasons qualified patients did not wish to participate; and [3] reasons for screen failure [SF] in patients agreeing to participate. We assess these in a 4-week prospective study including, consecutively, all patients with symptomatic disease for whom a treatment change was required. In addition, we performed a 6-month retrospective study to further evaluate reasons for SF.

RESULTS

A total of 106 patients (60 male [56.6%], 63 Crohn's disease [CD] [59.4%]), from ten centres across the world, were included in the prospective study. An RCT has not been proposed to 65 of them [mainly due to eligibility criteria]. Of the 41 patients to whom an RCT was offered, eight refused [mainly due to reluctance to receive placebo] and 28 agreed to participate. Among these 28 patients, five failed their screening and 23 were finally included in an RCT. A total of 107 patients (61 male [57%], 67 CD [62.6%]), from 13 centres worldwide, were included in our retrospective study of SFs. The main reason was insufficient disease activity.

CONCLUSION

This first multicentre study analysing reasons for non-enrolment in IBD RCTs shows that we lose patients at each step. Eligibility criteria, the risk of placebo assignment, and insufficient disease activity were part of the main barriers.

The Exacerbating Effects of the Tumor Necrosis Factor in Cardiovascular Stenosis: Intimal Hyperplasia

TNF-α functions as a master regulator of inflammation, and it plays a prominent role in several immunological diseases. By promoting important cellular mechanisms, such as cell proliferation, migration, and phenotype switch, TNF-α induces its exacerbating effects, which are the underlying cause of many proliferative diseases such as cancer and cardiovascular disease. TNF-α primarily alters the immune component of the disease, which subsequently affects normal functioning of the cells. Monoclonal antibodies and synthetic drugs that can target TNF-α and impair its effects have been developed and are currently used in the treatment of a few select human diseases. Vascular restenosis is a proliferative disorder that is initiated by immunological mechanisms. In this review, the role of TNF-α in exacerbating restenosis resulting from neointimal hyperplasia, as well as molecular mechanisms and cellular processes affected or induced by TNF-α, are discussed. As TNF-α-targeting drugs are currently not approved for the treatment of restenosis, the summation of the topics discussed here is anticipated to provide information that can emphasize on the use of TNF-α-targeting drug candidates to prevent vascular restenosis.

Disease clearance in ulcerative colitis: A new therapeutic target for the future

Advancements in murine modeling systems for ulcerative colitis have diversified our understanding of the pathophysiological factors involved in disease onset and progression. This has fueled the identification of molecular targets, resulting in a rapidly expanding therapeutic armamentarium. Subsequently, management strategies have evolved from symptomatic resolution to well-defined objective endpoints, including clinical remission, endoscopic remission and mucosal healing. While the incorporation of these assessment modalities has permitted targeted intervention in the context of a natural disease history and the prevention of complications, studies have consistently depicted discrepancies associated with ascertaining disease status through clinical and endoscopic measures. Current recommendations lack consideration of histological healing. The simultaneous achievement of clinical, endoscopic, and histologic remission has not been fully investigated. This has laid the groundwork for a novel therapeutic outcome termed disease clearance (DC). This article summarizes the concept of DC and its current evidence.

Guselkumab in Patients With Moderately to Severely Active Ulcerative Colitis: QUASAR Phase 2b Induction Study

BACKGROUND & AIMS

The QUASAR Phase 2b Induction Study evaluated the efficacy and safety of guselkumab, an interleukin-23p19 subunit antagonist, in patients with moderately to severely active ulcerative colitis (UC) with prior inadequate response and/or intolerance to corticosteroids, immunosuppressants, and/or advanced therapy.

METHODS

In this double-blind, placebo-controlled, dose-ranging, induction study, patients were randomized (1:1:1) to receive intravenous guselkumab 200 or 400 mg or placebo at weeks 0/4/8. The primary endpoint was clinical response (compared with baseline, modified Mayo score decrease ≥30% and ≥2 points, rectal bleeding subscore ≥1-point decrease or subscore of 0/1) at week 12. Guselkumab and placebo week-12 clinical nonresponders received subcutaneous or intravenous guselkumab 200 mg, respectively, at weeks 12/16/20 (uncontrolled study period).

RESULTS

The primary analysis population included patients with baseline modified Mayo scores ≥5 and ≤9 (intravenous guselkumab 200 mg, n = 101; 400 mg, n = 107; placebo, n = 105). Week-12 clinical response percentage was greater with guselkumab 200 mg (61.4%) and 400 mg (60.7%) vs placebo (27.6%; both P < .001). Greater proportions of guselkumab-treated vs placebo-treated patients achieved all major secondary endpoints (clinical remission, symptomatic remission, endoscopic improvement, histo-endoscopic mucosal improvement, and endoscopic normalization) at week 12. Among guselkumab week-12 clinical nonresponders, 54.3% and 50.0% of patients in the 200- and 400-mg groups, respectively, achieved clinical response at week 24. Safety was similar among guselkumab and placebo groups.

CONCLUSIONS

Guselkumab intravenous induction was effective vs placebo in patients with moderately to severely active UC. Guselkumab was safe, and efficacy and safety were similar between guselkumab dose groups.

CLINICALTRIALS

gov number: NCT04033445.

Baseline Peripheral Blood Mononuclear Cell Transcriptomics Before Ustekinumab Treatment Is Linked With Crohn's Disease Clinical Response at 1 Year

INTRODUCTION

Ustekinumab, a monoclonal antibody to the p40 subunit of interleukin (IL)-12 and IL-23, is used for Crohn's disease (CD), and the documented clinical remission rate after 1 year was observed in approximately 50% of patients. We aimed to identify predictors for a clinical response using peripheral blood obtained from patients with CD just before ustekinumab treatment initiation.

METHODS

RNA extraction from peripheral blood mononuclear cells was followed by mRNA paired-end sequencing. Differential gene expression was performed using DESeq2.

RESULTS

We processed samples from 36 adults with CD (13 men, 36%) obtained at baseline before starting ustekinumab treatment. Twenty-two of 36 (61%) were defined as responders and 14/36 (39%) as nonresponders after 1 year based on Physician Global Assessment. Differential gene expression between responders (n = 22) and nonresponders (n = 14) did not show a gene expression signature that passed false discovery rate (FDR) correction. However, the analyses identified 68 genes, including CXCL1/2/3, which were induced in nonresponders vs responders with P < 0.05 and fold change above 1.5. Functional annotation enrichments of these 68 genes using ToppGene indicated enrichment for cytokine activity (FDR = 1.98E-05), CXCR chemokine receptor binding (FDR = 2.11E-05), IL-10 signaling (FDR = 5.03E-07), genes encoding secreted soluble factors (FDR = 1.73E-05), and myeloid dendritic cells (FDR = 1.80E-08).

DISCUSSION

No substantial differences were found in peripheral blood mononuclear cell transcriptomics between responders and nonresponders. However, among the nonresponders, we noted an increased inflammatory response enriched for pathways linked with cytokine activity and chemokine receptor binding and innate myeloid signature. A larger cohort is required to validate and further explore these findings.

SGLT2 inhibitors prevent LPS-induced M1 macrophage polarization and alleviate inflammatory bowel disease by downregulating NHE1 expression

BACKGROUND

Classically activated M1 macrophages, characterized by aberrant glycolysis and secretion of inflammatory cytokines, play pivotal roles in inflammatory diseases, including inflammatory bowel disease (IBD). Recently, sodium-glucose co-transporter 2 (SGLT2) inhibitors were shown to suppress Na+/H+ exchanger 1 (NHE1) and Na+/Ca2+ exchanger 1 (NCX1) activity, regulating downstream intracellular Ca2+ concentrations in cardiomyocytes. However, whether SGLT2 inhibitors regulate M1 macrophage polarization by downregulating NHE1 and NCX1 remains unknown.

METHODS

We analyzed cellular responses to SGLT2 inhibitors using mouse bone marrow-derived macrophages and peritoneal macrophages treated with lipopolysaccharide (LPS). To induce IBD, we used a dextran sulfate sodium salt-induced colitis mouse model.

RESULTS

We observed that NHE1 and NCX1 were overexpressed in LPS-treated macrophages, leading to M1 macrophage polarization. Mechanistically, NHE1 and NCX1-mediated Ca2+ accumulation in the macrophage resulted in enhanced glycolysis by promoting PI3K/AKT/mTORC1 signaling. SGLT2 inhibitors suppressed both the expression levels and activities of NHE1 and NCX1, and consequently downregulated PI3K/AKT/mTORC1 signaling and glycolysis in LPS-treated macrophages. We observed inhibition of LPS-stimulated M1 polarization and cytokine production by SGLT2 inhibitors in vitro, ex vivo, and in an IBD mouse model.

CONCLUSIONS

NHE1 promotes M1 macrophage polarization and SGLT2 inhibitors are a novel strategy to treat M1 macrophage-mediated inflammatory diseases, including IBD.

Stemming the tide with ileocecal Crohn's disease: when is pharmacotherapy enough?

INTRODUCTION

Crohn's disease (CD) mostly affects the terminal ileum and ileocecal region and up to 80% of patients end up requiring surgery. Previously reserved for complicated or refractory forms, surgery is now considered as an alternative to medical treatment in localized ileocecal disease.

AREAS COVERED

This review examines factors associated with response to medical treatment and those associated with the need for surgery in ileocecal CD to identify the patients' profile for whom pharmacotherapy might be enough. Factors associated with the recurrence and the postoperative complications are also reviewed to help the clinician identify patients for whom medical therapy might be preferred.

EXPERT’S OPINION

LIR!C study long-term follow-up data show that 38% of infliximab-treated patients were still treated with infliximab at the end of their follow-up, while 14% had switched to another biologic or had received immunomodulator or corticosteroid and 48% had CD-related surgery. Only the combination with an immunomodulator was associated with a greater likelihood of continuing infliximab. Patients with ileocecal CD for whom pharmacotherapy might be sufficient are probably those with no risk factors for CD-related surgery.In addition, patients with high risk of recurrence or of post-operative complications may benefit more from medical treatment than from surgery.

Precision medicine and drug optimization in adult inflammatory bowel disease patients

Inflammatory bowel diseases (IBD) encompass two main entities including ulcerative colitis and Crohn's disease. Although having a common global pathophysiological mechanism, IBD patients are characterized by a significant interindividual heterogeneity and may differ by their disease type, disease locations, disease behaviours, disease manifestations, disease course as well as treatment needs. Indeed, although the therapeutic armamentarium for these diseases has expanded rapidly in recent years, a proportion of patients remains with a suboptimal response to medical treatment due to primary non-response, secondary loss of response or intolerance to currently available drugs. Identifying, prior to treatment initiation, which patients are likely to respond to a specific drug would improve the disease management, avoid unnecessary side effects and reduce the healthcare expenses. Precision medicine classifies individuals into subpopulations according to clinical and molecular characteristics with the objective to tailor preventative and therapeutic interventions to the characteristics of each patient. Interventions would thus be performed only on those who will benefit, sparing side effects and expense for those who will not. This review aims to summarize clinical factors, biomarkers (genetic, transcriptomic, proteomic, metabolic, radiomic or from the microbiota) and tools that could predict disease progression to guide towards a step-up or top-down strategy. Predictive factors of response or non-response to treatment will then be reviewed, followed by a discussion about the optimal dose of drug required for patients. The time at which these treatments should be administered (or rather can be stopped in case of a deep remission or in the aftermath of a surgery) will also be addressed. IBD remain biologically complex, with multifactorial etiopathology, clinical heterogeneity as well as temporal and therapeutic variabilities, which makes precision medicine especially challenging in this area. Although applied for many years in oncology, it remains an unmet medical need in IBD.