Ustekinumab is effective for perianal fistulising Crohn's disease: a real-world experience and systematic review with meta-analysis

Extracellular Vesicles Delivered by a Nanofiber-Hydrogel Composite Enhance Healing In Vivo in a Model of Crohn's Disease Perianal Fistula

Perianal fistulas represent a common, aggressive, and disabling complication of Crohn's disease (CD). Despite recent drug developments, novel surgical interventions as well as multidisciplinary treatment approaches, the outcome is dismal, with >50% therapy failure rates. Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) offer potential therapeutic benefits for treating fistulizing CD, due to the pro-regenerative paracrine signals. However, a significant obstacle to clinical translation of EV-based therapy is the rapid clearance and short half-life of EVs in vivo. Here, an injectable, biodegradable nanofiber-hydrogel composite (NHC) microgel matrix that serves as a carrier to deliver MSC-derived EVs to a rat model of CD perianal fistula (PAF) is reported. It is found that EV-loaded NHC (EV-NHC) yields the best fistula healing when compared to other treatment arms. The MRI assessment reveals that the EV-NHC reduces inflammation at the fistula site and promotes tissue healing. The enhanced therapeutic outcomes are contributed by extended local retention and sustained release of EVs by NHC. In addition, the EV-NHC effectively reduces inflammation at the fistula site and promotes tissue healing and regeneration via macrophage polarization and neo-vascularization. This EV-NHC platform provides an off-the-shelf solution that facilitates its clinical translation.

Clinical effectiveness and safety of ustekinumab in youth with refractory inflammatory bowel disease: A retrospective cohort study

BACKGROUND

Inflammatory bowel disease (IBD) incidence and prevalence has been increasing worldwide. Limited data exists on the effectiveness of ustekinumab (UST) in children. We aimed to describe the effectiveness and safety of UST in pediatric patients with IBD.

METHODS

A single-center retrospective study was conducted between January 2017 and February 2022. The study included patients ≤16 years of age who were treated with UST and followed up for ≥1 year. Clinical remission was defined as a score of the Pediatric Crohn's Disease (CD) and Pediatric Ulcerative Colitis (UC) Activity Indices ≤10 at week 52.

RESULTS

Thirteen patients who had failed anti-tumor necrosis factor-α (anti-TNFα) therapy were included, eight (61.5%) with CD and five (38.5%) with UC. The median age was 13 years (interquartile range [IQR]: 11.5 to 14). UST treatment was initiated at a median age of 3 years (IQR: 2.3 to 7) after diagnosis. Ten patients (76.9%) achieved clinical remission. There were no statistically significant differences in characteristics between patients who achieved and did not achieve clinical remission. Biochemical remission (BioR) was achieved in six patients (46.2%). Body mass index (BMI) significantly improved, C-reactive protein (CRP) significantly decreased, and the need for corticosteroids significantly decreased in the remission group. Endoscopy conducted post-treatment in seven patients confirmed remission in six patients. Adverse events included two cases of infection and one of headache.

CONCLUSIONS

UST was effective as a secondary biologic therapy for the induction and maintenance of remission in patients with anti-TNFα refractory IBD. At one year, 84% of patients remained on UST with no severe adverse reactions reported.

Epidemiology and Treatment Patterns of Fistulizing Crohn's Disease in a Large, Real-World Australasian Cohort

Background and Aims

Fistulizing Crohn's Disease (fCD) affects up to 50% of people with Crohn's Disease over their lifetime. Despite this high prevalence, the burden of disease, treatment and natural history in the current biologic era are poorly described. This study explores demographic, disease and treatment factors in a real-world Australasian cohort.

Methods

A large real-world cohort of people with inflammatory bowel disease under routine care was interrogated in August 2023. Current fCD was defined as fistula(e) on most recent clinical, radiologic or endoscopic investigation; prior fCD was defined as the resolution of fistula(e) on most recent documentation.

Results

Of 3075 people with Crohn's Disease, 7.4% had current and 10.1% prior fCD (n = 224 & 311). Most patients were in Australia (77%), where 19.3% had current or previous fCD compared to 11% in New Zealand (P < .001). Patients with current or previous fCD were younger compared to those without (P = .003 & P < .001). Males were more commonly affected (P = .021). Current or prior fCD were more likely to be on biologic therapy (P < .001), with anti-tumor necrosis factor agents most frequently utilized. Conversely, those without fCD were more likely on Ustekinumab or Vedolizumab compared to current and prior fCD groups. People with fistulizing disease had higher hospitalization rates, while the prior fCD cohort had longer hospital admissions and more frequently required surgical intervention.

Conclusion

People with fCD used more health-care resources, making this an important area for further research into care gaps to improve outcomes and optimal treatment approaches.

Activated HLA-DR+CD38+ Effector Th1/17 Cells Distinguish Crohn's Disease-associated Perianal Fistulas from Cryptoglandular Fistulas

BACKGROUND

Perianal fistulas are a debilitating complication of Crohn's disease (CD). Due to unknown reasons, CD-associated fistulas are in general more difficult to treat than cryptoglandular fistulas (non-CD-associated). Understanding the immune cell landscape is a first step towards the development of more effective therapies for CD-associated fistulas. In this work, we characterized the composition and spatial localization of disease-associated immune cells in both types of perianal fistulas by high-dimensional analyses.

METHODS

We applied single-cell mass cytometry (scMC), spectral flow cytometry (SFC), and imaging mass cytometry (IMC) to profile the immune compartment in CD-associated perianal fistulas and cryptoglandular fistulas. An exploratory cohort (CD fistula, n = 10; non-CD fistula, n = 5) was analyzed by scMC to unravel disease-associated immune cell types. SFC was performed on a second fistula cohort (CD, n = 10; non-CD, n = 11) to comprehensively phenotype disease-associated T helper (Th) cells. IMC was used on a third cohort (CD, n = 5) to investigate the spatial distribution/interaction of relevant immune cell subsets.

RESULTS

Our analyses revealed that activated HLA-DR+CD38+ effector CD4+ T cells with a Th1/17 phenotype were significantly enriched in CD-associated compared with cryptoglandular fistulas. These cells, displaying features of proliferation, regulation, and differentiation, were also present in blood, and colocalized with other CD4+ T cells, CCR6+ B cells, and macrophages in the fistula tracts.

CONCLUSIONS

Overall, proliferating activated HLA-DR+CD38+ effector Th1/17 cells distinguish CD-associated from cryptoglandular perianal fistulas and are a promising biomarker in blood to discriminate between these 2 fistula types. Targeting HLA-DR and CD38-expressing CD4+ T cells may offer a potential new therapeutic strategy for CD-related fistulas.

Persistence, effectiveness and safety of ustekinumab and vedolizumab therapy for complex perianal fistula in Crohn's disease: The HEAL study from GETECCU

BACKGROUND

The efficacy of ustekinumab and vedolizumab for treating complex perianal fistula in Crohn's disease has been barely studied. We aimed to assess treatment persistence, clinical remission, and safety of these drugs in this context.

METHODS

Crohn's disease patients who had received ustekinumab or vedolizumab for the indication of active complex perianal fistula, were included. Clinical remission was defined according to Fistula Drainage Assessment Index (no drainage through the fistula upon gentle pressure) based on physicians' assessment.

RESULTS

Of 155 patients, 136 received ustekinumab, and 35 vedolizumab (16 received both). Median follow-up for ustekinumab was 27 months. Among those on ustekinumab, 54 % achieved remission, and within this group, 27 % relapsed during follow-up. The incidence rate of relapse was 11 % per patient-year. Multivariate analysis found no variables associated with treatment discontinuation or relapse. Median follow-up time for patients receiving vedolizumab was 19 months. Remission was achieved in 46 % of the patients receiving vedolizumab, and among them, 20 % relapsed during follow-up. The incidence rate of relapse was 7 % per patient-year. Adverse events were mild in 6 % on ustekinumab and 8 % on vedolizumab.

CONCLUSION

Ustekinumab and vedolizumab appear effective, achieving remission in around half of complex perianal fistula patients, with favorable safety profiles.

ECCO Guidelines on Therapeutics in Crohn's Disease: Surgical Treatment

This article is the second in a series of two publications on the European Crohn's and Colitis Organisation [ECCO] evidence-based consensus on the management of Crohn's disease. The first article covers medical management; the present article addresses surgical management, including preoperative aspects and drug management before surgery. It also provides technical advice for a variety of common clinical situations. Both articles together represent the evidence-based recommendations of the ECCO for Crohn's disease and an update of prior ECCO Guidelines.

Real-World Long-Term Persistence and Surgical Procedure-Free Period Among Bio-naïve Patients with Crohn's Disease and Fistula Initiated on Ustekinumab

INTRODUCTION

Fistula is a common complication of Crohn's disease (CD). Treatment with biologics has been associated with fistula healing. Long-term persistence is an important factor for a chronic inflammatory process such as fistula. This study described 24-month persistence and time-to-surgery endpoints among bio-naïve patients with CD and intestinal fistula who were initiated on ustekinumab.

METHODS

Adults with CD and any enteric or perianal fistula initiated on ustekinumab (index date) between September 23, 2016, and March 2, 2022, were selected from the IQVIA PharMetrics® Plus database and followed up to 24 months. Persistence on ustekinumab (no gaps in days of supply of > 120 days) and composite endpoints of being persistent while on monotherapy and persistent while corticosteroid free were also assessed. The date of surgery was defined as the date of first claim for any CD-related surgeries. Persistence and time-to-surgery endpoints were assessed from the index date until the earliest of discontinuation (event), immunomodulator or other biologic use (event), corticosteroid use (event), date of surgery (event), 24-month follow-up or data end (censoring) using Kaplan-Meier analyses.

RESULTS

The sample included 445 patients (mean age: 42.8 years; 56.6% female). The most common type of fistula was anal fistula (36.0%). At 24 months after ustekinumab initiation, 64.2% of patients remained persistent (95% confidence interval [CI] 55.8-71.4). Furthermore, 53.3% of patients were persistent while on monotherapy (95% CI 45.1-60.7), and 45.6% of patients were persistent while being corticosteroid free (95% CI 36.9-53.8). At 24 months, 22.8% (95% CI 17.0-30.3) of patients underwent any CD-related surgery.

CONCLUSION

This study quantified long-term persistence on ustekinumab among bio-naïve patients with CD and fistula. Over half of patients initiated on ustekinumab were persistent and persistent while on monotherapy 24 months after initiation. Time-to-surgery estimate was comparable to existing evidence. These findings support ustekinumab as a treatment option for long-term management of CD with fistula.

Management of Perianal Fistulizing Crohn's Disease

Perianal fistulizing Crohn's disease (CD) represents a severe phenotype of CD that is associated with significant morbidity and reduction in quality of life. Perianal fistulizing CD is caused by a complex interplay of genetic predisposition, immune dysregulation, gut dysbiosis, and various unknown physiological and mechanical factors. A multidisciplinary approach is hence required for optimal management . A detailed anatomical description and classification of perianal fistula, including comprehensive clinical, endoscopic, and radiological diagnostic workup, is an important prerequisite to treatment. For simple perianal fistulas, use of antibiotics and immunomodulators, with or without fistulotomy, are appropriate measures. The medical management of complex perianal fistula, on the other hand, requires adequate control of infection before initiation of therapy with immunomodulators. In active complex perianal fistula, anti-tumor necrosis factors remain the most accepted therapy, with concomitant use of antibiotics or immunomodulators enhancing the efficacy. For patients refractory to anti-tumor necrosis factors, treatment with anti-integrins, anti-interleukins, and small molecules is being evaluated. Mesenchymal stem cells, hyperbaric oxygen therapy, and exclusive enteral nutrition have also been investigated as adjunct therapies. Despite the expansion of the medical armamentarium, a large proportion of the patients require surgical interventions. In this review, we provide an up-to-date overview of the pathophysiology, clinical presentation, diagnosis, and medical management of perianal fistulizing CD. A brief overview of the surgical management of perianal fistulizing CD is also provided.

[Old and New Biologics and Small Molecules in Inflammatory Bowel Disease: Anti-interleukins]

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic inflammatory disease of the gastrointestinal tract. The introduction of biologics, particularly anti-interleukin (IL) agents, has revolutionized IBD treatment. This review summarizes the role of ILs in IBD pathophysiology and describes the efficacy and positioning of anti-IL therapies. We discuss the functions of key ILs in IBD and their potential as therapeutic targets. The review then discusses anti-IL therapies, focusing primarily on ustekinumab (anti-IL-12/23), risankizumab (anti-IL-23), and mirikizumab (anti-IL-23). Clinical trial data demonstrate their efficacy in inducing and maintaining remission in Crohn's disease and ulcerative colitis. The safety profiles of these agents are generally favorable. However, long-term safety data for newer agents are still limited. The review also briefly discusses emerging therapies such as guselkumab and brazikumab. Network meta-analyses suggest that anti-IL therapies perform well compared to other biological agents. These agents may be considered first- or second-line therapies for many patients, especially those with comorbidities or safety concerns. Anti-IL therapies represent a significant advancement in IBD treatment, offering effective and relatively safe options for patients with moderate to severe disease.

The potential for medical therapies to address fistulizing Crohn's disease: a state-of-the-art review

INTRODUCTION

Crohn's disease (CD) is a chronic, relapsing immune mediated disease, which is one of the two major types of inflammatory bowel disease (IBD). Fistulizing CD poses a significant clinical challenge for physicians. Effective management of CD requires a multidisciplinary approach, involving a gastroenterologist and a GI surgeon while tailoring treatment to each patient's unique risk factors, clinical representations, and preferences.

AREAS COVERED

This comprehensive review explores the intricacies of fistulizing CD including its manifestations, types, impact on quality of life, management strategies, and novel therapies under investigation.

EXPERT OPINION

Antibiotics are often used as first-line therapy to treat symptoms. Biologics that selectively target TNF-α, such infliximab (IFX), have shown high efficacy in randomized controlled trials. However, more than 50% of patients lose response to IFX, prompting them to explore alternative strategies. Current options include adalimumab and certolizumab pegol combination therapies, as well as small-molecule drugs targeting Janus kinases such as Upadacitinib. Furthermore, a promising treatment for complex fistulas is mesenchymal stem cells such as Darvadstrocel (Alofisel), an allogeneic stem cell-based therapy. However, surgical interventions are necessary for complex cases or intra-abdominal complications. Setons and LIFT procedures are the most common surgical options.

Diagnosis and management of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic and relapsing immune-mediated disease of the gastrointestinal tract with a gradually increasing global incidence and prevalence. A prolonged course of IBD leads to a decline in patient quality of life and the creation of a substantial economic burden on society. Owing to the lack of specific diagnostic markers, the diagnosis of IBD still needs a gold standard based on a combination of clinical manifestations, imaging, laboratory, and endoscopic results. Accordingly, the current goals of IBD treatment are to alleviate clinical symptoms and reduce recurrence rates. Therefore, it is imperative to develop a standard set of procedures to diagnose and treat IBD. In this review, we summarize prominent and emerging studies, outline classical and contemporary approaches to diagnosing and managing IBD, and integrate multiple guidelines. Furthermore, we propose the possibility of establishing an early and comprehensive diagnostic workflow and personalized management strategy in the future. We aim to enhance the quality and standardization of diagnostic and treatment procedures for IBD.

Safety and Effectiveness of Ustekinumab for Crohn's Disease With Perianal Manifestations: Ad hoc Analysis Data From 1-Year Post-Marketing Surveillance Study in Japan

Background

Crohn's disease (CD) is an immune-mediated inflammatory disorder of the gastrointestinal tract with perianal disease being one of the challenging possible manifestations. Here, we report, an ad hoc analysis of the safety and effectiveness of 1-year use of ustekinumab (UST) for CD in patients with perianal manifestations using post-marketing surveillance (PMS) data in Japan.

Methods

Among 341 patients enrolled in the PMS, 229 and 224 patients who had baseline Crohn's Disease Activity Index (CDAI) data used for evaluating perianal manifestations were included in the safety and efficacy analysis sets, respectively. Incidence of adverse drug reactions, clinical remission, the mean or its change in CDAI scores, and CDAI items were evaluated through week 52 in the presence or absence of perianal manifestations at baseline. The prevalence of perianal manifestations was also described.

Results

Comparing patients with and without baseline perianal manifestations at week 52, there was no difference in ADR incidence (9.1% [n = 66] vs. 15.3% [n = 163]), no difference in clinical remission (68.3% vs. 59.9%; P = 0.269), and decreased mean change of CDAI score (-82.9 [n = 60] vs. -68.8 [n = 137]). The proportion of patients with perianal manifestations decreased after UST treatment in both biologics-naïve patients (23.5% [n = 4/17]) and patients who had received biologics (35.0% [n = 14/40]) at week 52.

Conclusions

In Japanese clinical practice, UST is safe and effective in CD patients with and without perianal manifestations. The therapy might be also beneficial in those with manifestations regardless of prior use of other biologics.

Ustekinumab in the Treatment of Inflammatory Bowel Diseases: Evolving Paradigms

Inflammatory bowel diseases, comprising Crohn's disease (CD) and ulcerative colitis (UC), are chronic, relapsing, and remitting immune-mediated inflammatory diseases affecting the gastrointestinal tract. Ustekinumab (UST) is a monoclonal antibody that blocks the p40 subunit of the anti-interleukin (IL) 12/23. Pivotal trials (CERTIFI and UNITI-IM for CD, UNIFI for UC) established the efficacy of UST for the induction and maintenance of remission in both CD and UC, with the most favorable results in naïve patients to biologics. In recent years, a wealth of 'real-world' data has emerged supporting positive clinical, endoscopic, and histological outcomes in patients treated with UST, as well as reassuring safety data. More recently, the results of the first head-to-head trials of UST and tumor necrosis factor (TNF) antagonists were reported. Moreover, a number of studies exploring the role of UST in specific clinical settings, such as perianal CD, postoperative complications and recurrence, extraintestinal manifestations, chronic antibiotic-refractory pouchitis, and pregnancy, were reported. This review explores the results reported to date on UST, including those from pivotal trials, real-world data, and emerging studies regarding therapeutic drug monitoring and immunogenicity. The safety profile of UST was also reviewed.

Clinical use of biologics for Crohn's disease in adults: lessons learned from real-world studies

INTRODUCTION

The therapeutic armamentarium for managing Crohn's disease (CD) has expanded significantly in recent decades. Several biologics with three different mechanisms of action [anti-tumor necrosis factor (TNF)-α, anti-integrin α4β7, and anti-IL 12/23] are currently available to manage CD.

AREA COVERED

This narrative review aims to summarize the most significant efficacy and safety data on the use of infliximab (IFX), adalimumab (ADA), vedolizumab (VDZ) and ustekinumab (UST) for the treatment of CD obtained from studies conducted in the real world (RW), compared to the results of randomized clinical trials (RCTs).

EXPERT OPINION

RW studies reported that biologic agents included in this analysis have higher remission rates and lower adverse event rates than findings from RCTs for treating patients with CD. All biological agents have proven effective and safe in RW studies, even when using biosimilars or switching to subcutaneous administration of the molecules for which they are available. Finally, anti-TNF-α agents, particularly IFX, have a higher rate of adverse events (AEs) than VDZ and UST. Therefore, patients at higher risk of AEs may benefit from other biologics than anti-TNF-α. However, further long-term RW studies are needed to confirm these findings.

Choosing Therapy for Moderate to Severe Crohn's Disease

The availability of approved therapies for Crohn's disease has significantly increased over the past decade. To choose the appropriate therapy for the patient, ideally head to head studies, and data on positioning could help the provider individualize the decision. Due to the paucity of head-to-head trial data, we turn to network meta-analysis and real-world studies to help guide our treatment choices. Ultimately, the best approach is to consider each patient on an individual basis, taking into consideration the characteristics of their disease, individual risk factors, extra-intestinal manifestations, co-morbid conditions, patient age, cost, and personal preferences. In this review, we summarize the evidence comparing biologic as well as small molecule therapies for the treatment of moderate-to-severe Crohn's disease. We have summarized the evidence in relation to factors such as efficacy, fistulizing disease, pregnancy, infection risk, and co-existing conditions.

Ustekinumab trough levels in children with Crohn's disease refractory to anti-tumor necrosis factor agents: a prospective case series of off-label use

Background: Ustekinumab is used off-label in pediatric Crohn's disease refractory to anti-tumor necrosis factor. Data on optimal dosing, target trough levels, and potential benefit of therapeutic drug monitoring in children treated with ustekinumab are limited. Materials and Methods: We describe a series of six adolescents who consented to be treated with ustekinumab. We measured their trough levels, C-reactive protein, and fecal calprotectin before every administration. Results: Standard adult dosing was effective to achieve biochemical remission (fecal calprotectin < 250 mg/kg) in one patient and clinical remission (resolution of symptoms) in another. The other four patients failed to respond on standard dosing and underwent intravenous re-induction and interval shortening to increase ustekinumab trough levels. This resulted in biochemical remission in one patient and clinical remission in another, suggesting an exposure-response relationship. The remaining two patients had no therapeutic benefit, and ustekinumab was discontinued. Conclusion: In this report, we show that ustekinumab can induce remission in pediatric patients with anti-tumor necrosis factor refractory Crohn's disease. It is worth escalating the dose before abandoning the drug as ineffective. Prospective studies in children are needed to determine long-term efficacy of ustekinumab, usefulness of therapeutic drug monitoring strategies, and, if applicable, optimal target trough levels.

Management of Perianal Crohn's Disease

Perianal Crohn's disease affects 25%-35% of patients with Crohn's disease and has proven to be one of the most difficult complications of the disease to treat. Patients with perianal Crohn's disease have lower health-related quality of life scores typically related to pain and fecal incontinence. In addition, patients with perianal Crohn's disease have higher rates of hospitalizations, surgeries, and overall healthcare costs. A multidisciplinary approach is necessary for the successful management of Crohn's disease with perianal fistula. Medical management is required to treat the underlying immune dysregulation to heal the luminal inflammation and the inflammation within the fistula tracts. Current options for medical therapy include biologics, dual therapy with thiopurines, therapeutic drug monitoring, and a close follow-up. Surgical management is critical to drain abscesses before immunosuppressive therapy and place setons when appropriate. Once the patient's inflammatory burden is well managed, definitive surgical therapies including fistulotomies, advancement flaps, and ligation of intersphincteric fistula tract procedures can be considered. Most recently, the use of stem cell therapy in the treatment of perianal fistula has given new hope to the cure of perianal fistula in Crohn's disease. This review will outline the most current data in the medical and surgical management of perianal Crohn's disease.

In-hospital management of inflammatory bowel disease

PURPOSE OF REVIEW

The management of hospitalized patients with inflammatory bowel disease (IBD) is complex. Despite considerable therapeutic advancements in outpatient ulcerative colitis and Crohn's disease management, the in-hospital management continues to lag with suboptimal outcomes. The purpose of this review is to provide a brief overview of our approach to managing patients hospitalized with acute severe ulcerative colitis (ASUC) and Crohn's disease-related complications, followed by a summary of emerging evidence for new management approaches.

RECENT FINDINGS

ASUC has seen the emergence of well validated prognostic models for colectomy as well as the development of novel treatment strategies such as accelerated infliximab dosing, Janus kinase inhibitor therapy, and sequential therapy, yet the rate of colectomy for steroid-refractory ASUC has not meaningfully improved. Crohn's disease has seen the development of better diagnostic tools, early Crohn's disease-related complication stratification and identification, as well as better surgical techniques, yet the rates of hospitalization and development of Crohn's disease-related complications remain high.

SUMMARY

Significant progress has been made in the in-hospital IBD management; however, both the management of ASUC and hospitalized Crohn's disease remain a challenge with suboptimal outcomes. Critical knowledge gaps still exist, and dedicated studies in hospitalized patients with IBD are needed to address them.

Management of Non-response and Loss of Response to Anti-tumor Necrosis Factor Therapy in Inflammatory Bowel Disease

Anti-tumor necrosis factor (anti-TNF) therapy has been successfully used as first-line biologic treatment for moderate-to-severe inflammatory bowel disease (IBD), in both "step-up" and "top-down" approaches, and has become a cornerstone of IBD management. However, in a proportion of patients the effectiveness of anti-TNF therapy is sub-optimal. Either patients do not achieve adequate initial response (primary non-response) or they lose response after initial success (loss of response). Therapeutic drug monitoring determines drug serum concentrations and the presence of anti-drug antibodies (ADAbs) and can help guide treatment optimization to improve patient outcomes. For patients with low drug concentrations who are ADAb-negative or display low levels of ADAbs, dose escalation is recommended. Should response remain unchanged following dose optimization the question whether to switch within class (anti-TNF) or out of class (different mechanism of action) arises. If ADAb levels are high and the patient has previously benefited from anti-TNF therapy, then switching within class is a viable option as ADAbs are molecule specific. Addition of an immunomodulator may lead to a decrease in ADAbs and a regaining of response in a proportion of patients. If a patient does not achieve a robust therapeutic response with an initial anti-TNF despite adequate drug levels, then switching out of class is appropriate. In conjunction with the guidance above, other factors including patient preference, age, comorbidities, disease phenotype, extra-intestinal manifestations, and treatment costs need to be factored into the treatment decision. In this review we discuss current evidence in this field and provide guidance on therapeutic decision-making in clinical situations.

The Optimal Management of Fistulizing Crohn's Disease: Evidence beyond Randomized Clinical Trials

Fistulizing Crohn's disease (FCD) remains the most challenging aspect of treating patients with CD. FCD can occur in up to 30% of patients with CD and may lead to significant disability and impaired quality of life. The optimal treatment strategies for FCD require a multidisciplinary approach, including a combined medical and surgical approach. The therapeutic options for FCD are limited due to sparse evidence from randomized clinical trials (RCTs). The current recommendations are mainly based on post hoc analysis from RCTs, real-world clinical studies and expert opinion. There is variation in everyday clinical practice amongst gastroenterologists and surgeons. The evidence for anti-tumor necrosis factor therapy is the strongest in the treatment of FCD. However, long-term fistula healing can be achieved in only 30-50% of patients. In recent years, emerging data in the advent of therapeutic modalities, including the use of new biologic agents, therapeutic drug monitoring, novel surgical methods and mesenchymal stem cell therapy, have been shown to improve outcomes in achieving fistula healing. This review summarizes the existing literature on current and emerging therapies to provide guidance beyond RCTs in managing FCD.

Biologics: how far can they go in Crohn’s disease?

Crohn’s disease is a chronic gastrointestinal inflammatory disorder, characterized by episodes of relapsing and remitting flares. As the disease mechanism becomes better elucidated, there is a significant increase in the number of available biologic therapies. This article summarizes and synthesizes current Food and Drug Administration-approved biological therapy for Crohn’s disease and examines the positioning of medical therapy as emerging biologics break onto the market.