Cellular immunotherapies and immune cell depleting therapies in inflammatory bowel diseases: the next magic bullet?

Despite significant advances in biologic and small molecule treatments and the emergence of combination therapies to treat inflammatory bowel diseases (IBD) a large unmet need remains to control intestinal inflammation. New approaches targeting several pathways simultaneously with a favorable safety profile and agents that trigger anti-inflammatory pathways to drive durable resolution of inflammation are needed. This article discusses novel cellular immunotherapies and immune cell depleting therapies in IBD, including CAR-T cell approaches, Tr1 and T regulatory (Treg) cells and cell depleting antibodies such as rosnilimab. These novel approaches have the potential to overcome current therapeutic limitations in the treatment of IBD.

Gut virome in inflammatory bowel disease and beyond.

OBJECTIVE: The gut virome is a dense community of viruses inhabiting the gastrointestinal tract and an integral part of the microbiota. The virome coexists with the other components of the microbiota and with the host in a dynamic equilibrium, serving as a key contributor to the maintenance of intestinal homeostasis and functions. However, this equilibrium can be interrupted in certain pathological states, including inflammatory bowel disease, causing dysbiosis that may participate in disease pathogenesis. Nevertheless, whether virome dysbiosis is a causal or bystander event requires further clarification. DESIGN: This review seeks to summarise the latest advancements in the study of the gut virome, highlighting its cross-talk with the mucosal microenvironment. It explores how cutting-edge technologies may build upon current knowledge to advance research in this field. An overview of virome transplantation in diseased gastrointestinal tracts is provided along with insights into the development of innovative virome-based therapeutics to improve clinical management. RESULTS: Gut virome dysbiosis, primarily driven by the expansion of Caudovirales, has been shown to impact intestinal immunity and barrier functions, influencing overall intestinal homeostasis. Although emerging innovative technologies still need further implementation, they display the unprecedented potential to better characterise virome composition and delineate its role in intestinal diseases. CONCLUSIONS: The field of gut virome is progressively expanding, thanks to the advancements of sequencing technologies and bioinformatic pipelines. These have contributed to a better understanding of how virome dysbiosis is linked to intestinal disease pathogenesis and how the modulation of virome composition may help the clinical intervention to ameliorate gut disease management.

Holistic healthcare in inflammatory bowel disease: time for patient-centric approaches?

Inflammatory bowel disease (IBD) is an emerging global disease characterised by chronic inflammation of the gastrointestinal tract. However, IBD is also manifested by several extraintestinal symptoms which, along with the intestinal symptoms, impact on the mental and emotional well-being of patients. Despite therapeutic advancements, only one-third of the diagnosed patients receiving approved medical treatments achieve short-term to medium-term remission. Consequently, patients who do not get successfully treated might resort to using complementary and alternative approaches to manage their symptoms, with or without consulting their treating clinician. Despite their possible potential, such approaches have various risks stemming from unknown adverse reactions and possible interference with medically approved therapies. In this study, we present the results of a well-performed literature review where we included randomised clinical trials which have assessed the efficacy of complementary approaches and dietary therapy on at least one of the following four outcomes: clinical remission, endoscopic remission, modulation of molecular biomarkers or quality of life metrics. By pointing out intraoutcome and interoutcome concordance, we identified possible candidates for clinical adoption and further study in larger randomised clinical trials covering the broad spectrum of IBD heterogeneity. We finally proposed a patient-centric clinical care model and a series of recommendations for stakeholders, with special attention to complementary approaches and dietary strategies, aimed at achieving holistic remission.

Biopsy and blood-based molecular biomarker of inflammation in IBD.

OBJECTIVE: IBD therapies and treatments are evolving to deeper levels of remission. Molecular measures of disease may augment current endpoints including the potential for less invasive assessments. DESIGN: Transcriptome analysis on 712 endoscopically defined inflamed (Inf) and 1778 non-inflamed (Non-Inf) intestinal biopsies (n=498 Crohn's disease, n=421 UC and 243 controls) in the Mount Sinai Crohn's and Colitis Registry were used to identify genes differentially expressed between Inf and Non-Inf biopsies and to generate a molecular inflammation score (bMIS) via gene set variance analysis. A circulating MIS (cirMIS) score, reflecting intestinal molecular inflammation, was generated using blood transcriptome data. bMIS/cirMIS was validated as indicators of intestinal inflammation in four independent IBD cohorts. RESULTS: bMIS/cirMIS was strongly associated with clinical, endoscopic and histological disease activity indices. Patients with the same histologic score of inflammation had variable bMIS scores, indicating that bMIS describes a deeper range of inflammation. In available clinical trial data sets, both scores were responsive to IBD treatment. Despite similar baseline endoscopic and histologic activity, UC patients with lower baseline bMIS levels were more likely treatment responders compared with those with higher levels. Finally, among patients with UC in endoscopic and histologic remission, those with lower bMIS levels were less likely to have a disease flare over time. CONCLUSION: Transcriptionally based scores provide an alternative objective and deeper quantification of intestinal inflammation, which could augment current clinical assessments used for disease monitoring and have potential for predicting therapeutic response and patients at higher risk of disease flares.

Australian inflammatory bowel disease consensus statements for preconception, pregnancy and breast feeding.

OBJECTIVE: Because pregnancy outcomes tend to be worse in women with inflammatory bowel disease (IBD) than in those without, we aimed to update consensus statements that guide the clinical management of pregnancy in patients with IBD. DESIGN: A multidisciplinary working group was established to formulate these consensus statements. A modified RAND/UCLA appropriateness method was used, consisting of a literature review, online voting, discussion meeting and a second round of voting. The overall agreement among the delegates and appropriateness of the statement are reported. RESULTS: Agreement was reached for 38/39 statements which provide guidance on management of pregnancy in patients with IBD. Most medications can and should be continued throughout pregnancy, except for methotrexate, allopurinol and new small molecules, such as tofacitinib. Due to limited data, no conclusion was reached on the use of tioguanine during pregnancy. Achieving and maintaining IBD remission before conception and throughout pregnancy is crucial to optimise maternofetal outcomes. This requires a multidisciplinary approach to engage patients, allay anxieties and maximise adherence tomedication. Intestinal ultrasound can be used for disease monitoring during pregnancy, and flexible sigmoidoscopy or MRI where clinically necessary. CONCLUSION: These consensus statements provide up-to-date, comprehensive recommendations for the management of pregnancy in patients with IBD. This will enable a high standard of care for patients with IBD across all clinical settings.

Managing metastatic Crohn's disease: a single center experience, review of the current evidence, and treatment algorithm.

BACKGROUND: Crohn's disease (CD) is an inflammatory bowel disease (IBD) that, besides gastrointestinal symptoms, may encompass extra-intestinal symptoms, such as dermatological manifestations. Of those, metastatic CD (MCD) is a rare extra-intestinal manifestation for which the management is uncertain. METHODS: We conducted a retrospective case series of patients with MCD seen at the University hospital Leuven, Belgium, combined with an overview of the recent literature. Electronic medical records were searched from January 2003 till April 2022. For the literature search, Medline, Embase, Trip Database, and The Cochrane Library were searched from inception to April 1, 2022. RESULTS: A total of 11 patients with MCD were retrieved. In all cases noncaseating granulomatous inflammation was found on skin biopsies. Two adults and one child were diagnosed with MCD prior to their diagnosis of CD. Seven patients were treated with steroids (intralesional, topical or systemic). Six patients needed a biological therapy to treat MCD. Surgical excision was performed in three patients. All patients reported a successful outcome and most cases achieved remission. The literature search yielded 53 articles, including three reviews, three systematic reviews, 30 case reports and six case series. A treatment algorithm was generated based on literature and multidisciplinary discussion. CONCLUSION: MCD remains a rare entity and diagnosis is often difficult. A multidisciplinary approach including skin biopsy is necessary to diagnose and treat MCD efficiently. Outcome is generally favorable, and lesions respond well to steroids and biologicals. We propose a treatment algorithm based on the available evidence and multidisciplinary discussion.

The role of serology, liver function tests and imaging in screening of primary sclerosing cholangitis: the HelPSCreen score.

OBJECIVES: At present, no sensitive or specific screening test exists for primary sclerosing cholangitis (PSC). PSC screening is mainly based on elevated alkaline phosphatase (ALP) in patients with inflammatory bowel disease (IBD). We aimed to produce a screening score based on laboratory tests to predict the likelihood of PSC. Moreover, we evaluated the additional roles of liver histology and magnetic resonance cholangiopancreatography (MRCP) in the diagnosis of PSC. MATERIALS AND METHODS: The data of 385 patients who came for their first endoscopic retrograde cholangiography (ERC) to confirm PSC diagnosis were retrieved from the PSC registry of the Helsinki University Hospital. Overall, 69 patients referred for ERC with suspected PSC, in whom PSC was excluded by ERC or liver biopsy and MRCP, served as controls. We included patients' demographics and 13 laboratory test results in the analysis. Variables with significant odds ratios were selected for multivariate logistic regression, which was used to create a novel scoring system for PSC. The presence of IBD, serum perinuclear anti-neutrophil cytoplasmic antibodies, and ALP levels demonstrated the highest predictive value for PSC. A score was assigned for each statistically significant predictor. RESULTS: The optimal cut-off point for the score was ≥3, with an AUC of 0.83 (95%CI: 0.78-0.88). The addition of liver histology or MRCP findings to the score did not add a predictive value. CONCUSIONS: In conclusion, we created a novel, simple scoring system to screen the probability of PSC. The HelPSCreen-score may help to assess the disease prevalence and to target further investigations in patients suspected of PSC.

First-line treatment with infliximab versus conventional treatment in children with newly diagnosed moderate-to-severe Crohn's disease: an open-label multicentre randomised controlled trial.

OBJECTIVE: In newly diagnosed paediatric patients with moderate-to-severe Crohn's disease (CD), infliximab (IFX) is initiated once exclusive enteral nutrition (EEN), corticosteroid and immunomodulator therapies have failed. We aimed to investigate whether starting first-line IFX (FL-IFX) is more effective to achieve and maintain remission than conventional treatment. DESIGN: In this multicentre open-label randomised controlled trial, untreated patients with a new diagnosis of CD (3-17 years old, weighted Paediatric CD Activity Index score (wPCDAI) >40) were assigned to groups that received five infusions of 5 mg/kg IFX at weeks 0, 2, 6, 14 and 22 (FL-IFX), or EEN or oral prednisolone (1 mg/kg, maximum 40 mg) (conventional). The primary outcome was clinical remission on azathioprine, defined as a wPCDAI <12.5 at week 52, without need for treatment escalation, using intention-to-treat analysis. RESULTS: 100 patients were included, 50 in the FL-IFX group and 50 in the conventional group. Four patients did not receive treatment as per protocol. At week 10, a higher proportion of patients in the FL-IFX group than in the conventional group achieved clinical (59% vs 34%, respectively, p=0.021) and endoscopic remission (59% vs 17%, respectively, p=0.001). At week 52, the proportion of patients in clinical remission was not significantly different (p=0.421). However, 19/46 (41%) patients in the FL-IFX group were in clinical remission on azathioprine monotherapy without need for treatment escalation vs 7/48 (15%) in the conventional group (p=0.004). CONCLUSIONS: FL-IFX was superior to conventional treatment in achieving short-term clinical and endoscopic remission, and had greater likelihood of maintaining clinical remission at week 52 on azathioprine monotherapy. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT02517684).

Long-term maintenance treatment with 300 mg thiamine for fatigue in patients with inflammatory bowel disease: results from an open-label extension of the TARIF study.

OBJECTIVE AND AIMS: Fatigue is common in inflammatory bowel disease (IBD). In a RCT we demonstrated reductions in fatigue after 4 weeks' treatment with high-dose oral thiamine. We aimed to investigate whether 300 mg thiamine daily for 12 weeks could maintain the achieved levels of fatigue in patients with IBD after a 4-week intervention with high-dose thiamine; and evaluate the effect of a 6-month period where patients were free to take oral thiamine. METHODS: A randomised, open-label, controlled trial, performed as a long-term extension (LTE) study of an initial randomised, high-dose thiamine trial. Patients were allocated 1:1 to 300 mg oral thiamine or no thiamine for 12 weeks. Subsequently, the patients were allowed to self-treat with over-the-counter (OTC) oral thiamine 6-month. RESULTS: Regardless of allocation in the LTE study fatigue severity increased in the study period. No significant effect of 300 mg oral thiamine were found, when stratifying for initial allocation in the high-dose study or fatigue level at entry in the LTE study. Patients who took OTC thiamine had lower level of fatigue 6 month later (7.8; 95% CI: 5.5-10.1) when compared to the remains (11.0; 95% CI: 9.2-12.8) (p = .02). After the 6-months follow-up without restrictions, 66% of patients had reached normal fatigue levels. CONCLUSIONS: We found no beneficial effect on fatigue from thiamine taken in doses of 300 mg per day for 12 weeks following high-dose treatment. After a 6-months follow-up without restrictions 66% had reached a normal level of fatigue. CLINICAL TRIAL REGISTRATION: The trial was registered at ClinicalTrials.gov under study identifier NCT03634735.

Emerging treatment options for extraintestinal manifestations in IBD.

Extraintestinal manifestations (EIMs) are frequently observed in IBDs and contribute considerably to morbidity and mortality. They have long been considered a difficult to treat entity due to limited therapy options, but the increasing use of anti-tumour necrosis factors has dramatically changed the therapeutic approach to EIM in recent years. Newly emerging therapies such as JAK inhibitors and anti-interleukin 12/23 will further shape the available armamentarium. Clinicians dealing with EIMs in everyday IBD practice may be puzzled by the numerous available biological agents and small molecules, their efficacy for EIMs and their potential off-label indications. Current guidelines on EIMs in IBD do not include treatment algorithms to help practitioners in the treatment decision-making process. Herein, we summarise knowledge on emerging biological treatment options and small molecules for EIMs, highlight current research gaps, provide therapeutic algorithms for EIM management and shed light on future strategies in the context of IBD-related EIMs.

Increased risk of inflammatory bowel disease among patients treated with rituximab in Iceland from 2001 to 2018.

OBJECTIVE: Immune-mediated diseases are on the rise after the introduction of powerful immunomodulating drugs. The objective of this study was to determine the population-based incidence rate of inflammatory bowel disease (IBD) among patients treated with the monoclonal antibody rituximab in Iceland and compare it to the baseline incidence rate of IBD in the general population. METHODS: We identified all patients treated with rituximab in Iceland from 2001 to 2018 through a central medicine database. IBD cases were indexed from medical records and ICD-10 codes and further confirmed by colonoscopy- and pathology reports. An experienced pathologist compared the pathology of IBD cases with matched controls of IBD patients. RESULTS: Lymphomas and related neoplasms were the most frequent indication for treatment with rituximab (n = 367) among the 651 patients included in the analysis. Following treatment, seven patients developed IBD: two cases of Crohn's disease, three with ulcerative colitis, and two with indeterminate IBD. The incidence rate of IBD among rituximab treated patients was 202 cases per 100,000 person-years. Comparing our data to IBD incidence in Iceland, rituximab treated patients have an age-adjusted hazard ratio of 6.6 for developing IBD. The risk did not correlate with dose or treatment duration. Prior diagnosis of an autoimmune illness did not increase the risk of IBD in rituximab treated patients. CONCLUSIONS: Patients on rituximab have a sixfold increased risk of developing IBD compared to the general population. This risk was not affected by the indication for treatment and was not associated with concurrent immune-mediated diseases. Summary This population-based retrospective cohort study included all patients receiving treatment with rituximab between 2001 and 2018 in Iceland and identified a sixfold increased risk of developing IBD when compared to the general population.

Clinical applications of artificial intelligence and machine learning-based methods in inflammatory bowel disease.

Our objective was to review and exemplify how selected applications of artificial intelligence (AI) might facilitate and improve inflammatory bowel disease (IBD) care and to identify gaps for future work in this field. IBD is highly complex and associated with significant variation in care and outcomes. The application of AI to IBD has the potential to reduce variation in healthcare delivery and improve quality of care. AI refers to the ability of machines to mimic human intelligence. The range of AI's ability to perform tasks that would normally require human intelligence varies from prediction to complex decision-making that more closely resembles human thought. Clinical applications of AI have been applied to study pathogenesis, diagnosis, and patient prognosis in IBD. Despite these advancements, AI in IBD is in its early development and has tremendous potential to transform future care.

Review of a paediatric inflammatory bowel disease service during the pandemic and the impact of the CNS role.

BACKGROUND: Inflammatory bowel disease (IBD) is a chronic relapsing and remitting condition. The COVID-19 pandemic has severely disrupted provision of medical care across the world. IBD clinical nurse specialists (CNSs) played a pivotal role in the care of children with IBD during the pandemic national lockdown and in the recovery phase. This article aims to look at the impact of COVID-19 on the paediatric IBD service in one children's hospital and the effect on the IBD CNSs' workload. METHOD: A retrospective review of clinical notes and the service's IBD database from January 2019 to September 2020. RESULTS: There was a significant increase in the number of email and telephone contacts to the IBD CNS team during lockdown. There was an increase in virtual clinics, and an increase in new IBD patients coming to the service, but a reduction in the number of face-to-face consultant clinics. CONCLUSION: COVID-19 has disrupted medical services to children with IBD and led to a reduction in face-to-face activities but has also led to a significant increase in virtual activities. CNSs have taken up a wider role to cover patient care during a time of both medical and nursing redeployment.

Adaptations to the British Society of Gastroenterology guidelines on the management of acute severe UC in the context of the COVID-19 pandemic: a RAND appropriateness panel.

OBJECTIVE: Management of acute severe UC (ASUC) during the novel COVID-19 pandemic presents significant dilemmas. We aimed to provide COVID-19-specific guidance using current British Society of Gastroenterology (BSG) guidelines as a reference point. DESIGN: We convened a RAND appropriateness panel comprising 14 gastroenterologists and an IBD nurse consultant supplemented by surgical and COVID-19 experts. Panellists rated the appropriateness of interventions for ASUC in the context of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Median scores and disagreement index (DI) were calculated. Results were discussed at a moderated meeting prior to a second survey. RESULTS: Panellists recommended that patients with ASUC should be isolated throughout their hospital stay and should have a SARS-CoV-2 swab performed on admission. Patients with a positive swab should be discussed with COVID-19 specialists. As per BSG guidance, intravenous hydrocortisone was considered appropriate as initial management; only in patients with COVID-19 pneumonia was its use deemed uncertain. In patients requiring rescue therapy, infliximab with continuing steroids was recommended. Delaying colectomy because of COVID-19 was deemed inappropriate. Steroid tapering as per BSG guidance was deemed appropriate for all patients apart from those with COVID-19 pneumonia in whom a 4-6 week taper was preferred. Post-ASUC maintenance therapy was dependent on SARS-CoV-2 status but, in general, biologics were more likely to be deemed appropriate than azathioprine or tofacitinib. Panellists deemed prophylactic anticoagulation postdischarge to be appropriate in patients with a positive SARS-CoV-2 swab. CONCLUSION: We have suggested COVID-19-specific adaptations to the BSG ASUC guideline using a RAND panel.

Designing clinical trials in paediatric inflammatory bowel diseases: a PIBDnet commentary.

INTRODUCTION: The optimal trial design for assessing novel therapies in paediatric IBD (PIBD) is a subject of intense ongoing global discussions and debate among the different stakeholders. However, there is a consensus that the current situation in which most medications used in children with IBD are prescribed as off-label without sufficient paediatric data is unacceptable. Shortening the time lag between adult and paediatric approval of drugs is of the upmost importance. In this position paper we aimed to provide guidance from the global clinical research network (Pediatric Inflammatory Bowel Disease Network, PIBDnet) for designing clinical trials in PIBD in order to facilitate drug approval for children. METHODS: A writing group has been established by PIBDnet and topics were assigned to different members. After an iterative process of revisions among the writing group and one face-to-face meeting, all statements have reached consensus of >80% as defined a priori. Next, all core members of PIBDnet voted on the statements, reaching consensus of >80% on all statements. Comments from the members were incorporated in the text. RESULTS: The commentary includes 18 statements for guiding data extrapolation from adults, eligibility criteria to PIBD trials, use of placebo, dosing, endpoints and recommendations for feasible trials. Controversial issues have been highlighted in the text. CONCLUSION: The viewpoints expressed in this paper could assist planning clinical trials in PIBD which are both of high quality and ethical, while remaining pragmatic.

Long-term prognosis of ulcerative colitis and its temporal changes between 1986 and 2015 in a population-based cohort in the Songpa-Kangdong district of Seoul, Korea.

OBJECTIVE: No population-based study has evaluated the natural course of UC over three decades in non-Caucasians. We aimed to assess the long-term natural course of Korean patients with UC in a population-based cohort. DESIGN: This Korean population-based, Songpa-Kangdong IBD cohort included all patients (n=1013) newly diagnosed with UC during 1986-2015. Disease outcomes and their predictors were evaluated. RESULTS: During the median follow-up of 105 months, the overall use of systemic corticosteroids, thiopurines and antitumour necrosis factor (anti-TNF) agents was 40.8%, 13.9% and 6.5%, respectively. Over time, the cumulative risk of commencing corticosteroids decreased, whereas that of commencing thiopurines and anti-TNF agents increased. During follow-up, 28.7% of 778 patients with proctitis or left-sided colitis at diagnosis experienced proximal disease extension. A total of 28 patients (2.8%) underwent colectomy, demonstrating cumulative risks of colectomy at 1, 5, 10, 20 and 30 years after diagnosis of 1.0%, 1.9%, 2.2%, 5.1% and 6.4%, respectively. Multivariate Cox regression analysis revealed that extensive colitis at diagnosis (HR 8.249, 95% CI 2.394 to 28.430), ever use of corticosteroids (HR 6.437, 95% CI 1.440 to 28.773) and diagnosis in the anti-TNF era (HR 0.224, 95% CI 0.057 to 0.886) were independent predictors of colectomy. The standardised mortality ratio in patients with UC was 0.725 (95% CI 0.508 to 1.004). CONCLUSION: Korean patients with UC may have a better clinical course than Western patients, as indicated by a lower colectomy rate. The overall colectomy rate has continued to decrease over the past three decades.

Discovery of biomarker candidates associated with the risk of short-term and mid/long-term relapse after infliximab withdrawal in Crohn's patients: a proteomics-based study.

OBJECTIVE: A subset of Crohn's disease (CD) patients experiences mid/long-term remission after infliximab withdrawal. Biomarkers are needed to identify those patients. DESIGN: New biomarkers of relapse were searched in the baseline serum of CD patients stopping infliximab when they were under combined therapy (antimetabolite and infliximab) and stable clinical remission (diSconTinuation in CrOhn's disease patients in stable Remission on combined therapy with Immunosuppressors cohort, n=102). From shotgun proteomics experiment (discovery step), biomarker candidates were identified and further targeted by selected reaction monitoring (verification step). The dataset was stratified to search for markers of short-term (<6 months) or mid/long-term relapse (>6 months). The risk of relapse and the predicting capacity associated with biomarker candidates were evaluated using univariate Cox model and log-rank statistic, respectively. To test their complementary predicting capacity, biomarker candidates were systematically combined in pairs. RESULTS: Distinct biomarker candidates were associated with the risk (HR) of short-term (15 proteins, 2.9

JAK selectivity for inflammatory bowel disease treatment: does it clinically matter?

The two major forms of inflammatory bowel disease (IBD), encompassing Crohn's disease (CD) and ulcerative colitis (UC), are chronic immune-mediated conditions characterised by an increased production of pro-inflammatory cytokines that act as critical drivers of intestinal inflammation. Anti-cytokine therapy has been shown to improve clinical outcomes in IBD. Janus kinases (JAKs) are tyrosine kinases that bind different intracellular cytokine receptors, leading to phosphorylation of signal transducer and activation of transcription molecules implicated on targeted gene transcription. Four isoforms of JAKs have been described: JAK1, JAK2, JAK3 and TYK2. Oral JAK inhibitors (JAKi) have been developed as synergic anti-cytokine therapy in IBD, showing different selectivity towards JAK isoforms. Tofacitinib, a pan-JAK inhibitor, has been recently approved for the treatment of moderate-to-severe UC. With the aim of improving the benefit: risk ratio of this drug class, several second-generation subtype-selective JAKi are under development. However, whether selective inhibition of JAK isoforms is associated with an increased clinical efficacy and/or a better safety profile remains debatable. The aim of this review is to critically review the preclinical and clinical data for the differential selectivity of JAK inhibitors and to summarise the potential clinical implications of the selective JAK inhibitors under development for UC and CD.

A blood-based prognostic biomarker in IBD.

OBJECTIVE: We have previously described a prognostic transcriptional signature in CD8 T cells that separates patients with IBD into two phenotypically distinct subgroups, termed IBD1 and IBD2. Here we sought to develop a blood-based test that could identify these subgroups without cell separation, and thus be suitable for clinical use in Crohn's disease (CD) and ulcerative colitis (UC). DESIGN: Patients with active IBD were recruited before treatment. Transcriptomic analyses were performed on purified CD8 T cells and/or whole blood. Phenotype data were collected prospectively. IBD1/IBD2 patient subgroups were identified by consensus clustering of CD8 T cell transcriptomes. In a training cohort, machine learning was used to identify groups of genes ('classifiers') whose differential expression in whole blood recreated the IBD1/IBD2 subgroups. Genes from the best classifiers were quantitative (q)PCR optimised, and further machine learning was used to identify the optimal qPCR classifier, which was locked down for further testing. Independent validation was sought in separate cohorts of patients with CD (n=66) and UC (n=57). RESULTS: In both validation cohorts, a 17-gene qPCR-based classifier stratified patients into two distinct subgroups. Irrespective of the underlying diagnosis, IBDhi patients (analogous to the poor prognosis IBD1 subgroup) experienced significantly more aggressive disease than IBDlo patients (analogous to IBD2), with earlier need for treatment escalation (hazard ratio=2.65 (CD), 3.12 (UC)) and more escalations over time (for multiple escalations within 18 months: sensitivity=72.7% (CD), 100% (UC); negative predictive value=90.9% (CD), 100% (UC)). CONCLUSION: This is the first validated prognostic biomarker that can predict prognosis in newly diagnosed patients with IBD and represents a step towards personalised therapy.