Humoral immune response and safety of SARS-CoV-2 vaccination in very early onset inflammatory bowel disease

Children with very early onset inflammatory bowel disease (VEO-IBD) may respond differently to coronavirus disease 2019 (COVID-19) immunization compared to healthy children or other patients with IBD. We recruited children with VEO-IBD <6 years of age and younger following receipt of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. Demographics, IBD characteristics, medication use, adverse events (AEs) and IBD exacerbations were collected. Blood draws (optional) were obtained for measurement of antireceptor binding domain (RBD) IgG antibodies following vaccination. Of 41 participants, none required emergency department visit or hospitalization due to AE, and only one experienced IBD exacerbation. Detectable antibody was present in 19/19 participants who provided blood sample; 6/7 participants (86%) had durable humoral response 12 months postvaccination. Children with VEO-IBD experience robust humoral immune response to COVID-19 immunization. Severe AEs were rare. These findings provide reassurance that children with VEO-IBD respond well and safely to SARS-CoV-2 vaccination.

The immunopathological landscape of human pre-TCRα deficiency: From rare to common variants

We describe humans with rare biallelic loss-of-function PTCRA variants impairing pre-α T cell receptor (pre-TCRα) expression. Low circulating naive αβ T cell counts at birth persisted over time, with normal memory αβ and high γδ T cell counts. Their TCRα repertoire was biased, which suggests that noncanonical thymic differentiation pathways can rescue αβ T cell development. Only a minority of these individuals were sick, with infection, lymphoproliferation, and/or autoimmunity. We also report that 1 in 4000 individuals from the Middle East and South Asia are homozygous for a common hypomorphic PTCRA variant. They had normal circulating naive αβ T cell counts but high γδ T cell counts. Although residual pre-TCRα expression drove the differentiation of more αβ T cells, autoimmune conditions were more frequent in these patients compared with the general population.

Clinicopathologic Characterization of Lymphocytic Colitis in the Pediatric Population

BACKGROUND

Lymphocytic colitis (LC) in the pediatric population has been associated with immune dysregulation.

METHODS

Single-center retrospective study of pediatric LC.

RESULTS

50 patients (35 female, 70%) with a median age of 12 years at diagnosis (interquartile range: 5.7-15.8) of LC were identified. At presentation, 11 patients (22%) had malnutrition, 16 (32%) had a known underlying immune dysregulation, 4 (8%) had celiac disease (CD), and none had a diagnosis of inflammatory bowel disease. The most common medications prior to diagnosis were non-steroidal anti-inflammatory drugs, proton pump inhibitor, and selective serotonin reuptake inhibitors (10% each). Colonic biopsies showed a median number of intraepithelial lymphocytes (IELs)/100 epithelial cells of 48 (range: 25-85), and only 10% of cases had neutrophilic cryptitis. Upper gastrointestinal tract findings included lymphocytic esophagitis (4%), and duodenal IELs without and with villous blunting (9% each) (n: 47). Ten patients (23%) had increased IELs in the terminal ileum (n: 43). Treatments including 5-ASA, budesonide, prednisone, and gluten-free diet improved symptoms in <50% of patients (n: 42), and all follow-up colonoscopies showed persistent LC (n: 13).

CONCLUSION

Our study supports the association of LC with immune-mediated conditions, most commonly celiac disease. Symptomatic improvement was seen in <50% of patients with none of the patients with repeat colonoscopy showing histologic improvement.

The intestinal microbiome of inflammatory bowel disease across the pediatric age range

Dysbiosis is associated with pediatric and adult-onset inflammatory bowel disease (IBD), but the role of dysbiosis and the microbiome in very early onset IBD (VEO-IBD) has not yet been described. Here, we aimed to demonstrate the impact of age and inflammation on microbial community structure using shotgun metagenomic sequencing in children with VEO-IBD, pediatric-onset IBD, and age-matched pediatric healthy controls (HC) observed longitudinally over the course of 8 weeks. We found disease-related differences in alpha and beta diversity between HC and children with IBD or VEO-IBD. Using a healthy microbial maturity index modeled from HC across the age range to characterize their gut microbiota, we found that children with pediatric-onset IBD and VEO-IBD had lower maturity than their age-matched HC groups, suggesting a disease effect on the microbial community. In addition, patients with pediatric IBD had significantly lower maturity than those with VEO-IBD, who had more heterogeneity at the youngest ages, highlighting differences in these two cohorts that were not captured in standard comparisons of alpha and beta diversity. These results demonstrate that young age and inflammation independently impact microbial community structure. However, the effect is not additive in the youngest patients, likely because of the heterogeneous and dynamic stool microbiome in this population.

Isolation of Epithelial and Stromal Cells from Colon Tissues in Homeostasis and Under Inflammatory Conditions

Inflammation of the gastrointestinal tract is a prevalent pathology in diseases such as inflammatory bowel disease (IBD). Currently, there are no therapies to prevent IBD, and available therapies to treat IBD are often sub-optimal. Thus, an unmet need exists to better understand the molecular mechanisms underlying intestinal tissue responses to damage and regeneration. The recent development of single-cell RNA (sc-RNA) sequencing-based techniques offers a unique opportunity to shed light on novel signaling pathways and cellular states that govern tissue adaptation or maladaptation across a broad spectrum of diseases. These approaches require the isolation of high-quality cells from tissues for downstream transcriptomic analyses. In the context of intestinal biology, there is a lack of protocols that ensure the isolation of epithelial and non-epithelial compartments simultaneously with high-quality yield. Here, we report two protocols for the isolation of epithelial and stromal cells from mouse and human colon tissues under inflammatory conditions. Specifically, we tested the feasibility of the protocols in a mouse model of dextran sodium sulfate (DSS)-induced colitis and in human biopsies from Crohn's patients. We performed sc-RNA sequencing analysis and demonstrated that the protocol preserves most of the epithelial and stromal cell types found in the colon. Moreover, the protocol is suitable for immunofluorescence staining of surface markers for epithelial, stromal, and immune cell lineages for flow cytometry analyses. This optimized protocol will provide a new resource for scientists to study complex tissues such as the colon in the context of tissue damage and regeneration. Key features • This protocol allows the isolation of epithelial and stromal cells from colon tissues. • The protocol has been optimized for tissues under inflammatory conditions with compromised cell viability. • This protocol is suitable for experimental mouse models of colon inflammation and human biopsies.

Canakinumab for the treatment of autoinflammatory very early onset- inflammatory bowel disease

Introduction

Therapeutic options are critically needed for children with refractory very early onset inflammatory bowel disease (VEO-IBD). Our aim was to evaluate clinical response to canakinumab, an anti-IL-1β monoclonal antibody, in patients with VEO-IBD whose phenotype resembles those with monogenic autoinflammatory disease.

Methods

This is a single center retrospective study of patients with VEO-IBD with autoinflammatory phenotype (AIP) in the absence of identified monogenic disease treated with canakinumab for >6 months. AIP was defined as confirmed IBD with associated signs of systemic inflammation in the absence of infection, including leukocytosis, markedly elevated inflammatory markers, and extraintestinal manifestations (recurrent fevers, oral ulcers, arthritis). Primary outcomes included clinical response in disease activity indices after 6 months of therapy. Secondary outcomes included rate of AIP signs and symptoms, growth, surgery, steroid use, hospitalizations, and adverse events.

Results

Nineteen patients were included: 47% with infantile onset, 58% classified as IBD-U, and 42% classified as CD. At baseline, 37% were biologic naïve, and canakinumab was used as dual therapy in 74% of patients. Clinical response was achieved in 89% with statistically significant improvement in PCDAI and PUCAI. Clinical remission was achieved in 32% of patients. There was significant improvement in the clinical manifestations of AIP and the biochemical markers of disease. Number of hospitalizations (p<0.01) and length of stay (p<0.05) decreased. Growth improved with median weight-for-length Z-score increasing from -1.01 to 1.1 in children less than 2 years old. There were minimal adverse events identified during the study period.

Conclusion

Canakinumab may be an effective and safe treatment for a subset of children with VEO-IBD with AIP, as well as older patients with IBD. This study highlights the importance of a precision medicine approach in children with VEO-IBD.

Efficacy and Outcomes of Faecal Microbiota Transplantation for Recurrent Clostridioides difficile Infection in Children with Inflammatory Bowel Disease

BACKGROUND

Children with inflammatory bowel disease [IBD] are disproportionally affected by recurrent Clostridioides difficile infection [rCDI]. Although faecal microbiota transplantation [FMT] has been used with good efficacy in adults with IBD, little is known about outcomes associated with FMT in paediatric IBD.

METHODS

We performed a retrospective review of FMT at 20 paediatric centres in the USA from March 2012 to March 2020. Children with and without IBD were compared with determined differences in the efficacy of FMT for rCDI. In addition, children with IBD with and without a successful outcome were compared with determined predictors of success. Safety data and IBD-specific outcomes were obtained.

RESULTS

A total of 396 paediatric patients, including 148 with IBD, were included. Children with IBD were no less likely to have a successful first FMT then the non-IBD affected cohort [76% vs 81%, p = 0.17]. Among children with IBD, patients were more likely to have a successful FMT if they received FMT with fresh stool [p = 0.03], were without diarrhoea prior to FMT [p = 0.03], or had a shorter time from rCDI diagnosis until FMT [p = 0.04]. Children with a failed FMT were more likely to have clinically active IBD post-FMT [p = 0.002] and 19 [13%] patients had an IBD-related hospitalisation in the 3-month follow-up.

CONCLUSIONS

Based on the findings from this large US multicentre cohort, the efficacy of FMT for the treatment of rCDI did not differ in children with IBD. Failed FMT among children with IBD was possibly related to the presence of clinically active IBD.

Ruxolitinib: Targeted Approach for Treatment of Autoinflammatory Very Early Onset Inflammatory Bowel Disease

Very early onset inflammatory bowel disease (VEO-IBD), diagnosed <6 years old, can be genetically and phenotypically distinct and more refractory than older-onset IBD. Identified causal monogenic defects have been targeted therapeutically in a small subset of VEO-IBD1; however, for most of these children, treatment strategies, such as phenotypic profiles, are critically needed to improve outcomes.

β-Hydroxybutyrate suppresses colorectal cancer

Colorectal cancer (CRC) is among the most frequent forms of cancer, and new strategies for its prevention and therapy are urgently needed1. Here we identify a metabolite signalling pathway that provides actionable insights towards this goal. We perform a dietary screen in autochthonous animal models of CRC and find that ketogenic diets exhibit a strong tumour-inhibitory effect. These properties of ketogenic diets are recapitulated by the ketone body β-hydroxybutyrate (BHB), which reduces the proliferation of colonic crypt cells and potently suppresses intestinal tumour growth. We find that BHB acts through the surface receptor Hcar2 and induces the transcriptional regulator Hopx, thereby altering gene expression and inhibiting cell proliferation. Cancer organoid assays and single-cell RNA sequencing of biopsies from patients with CRC provide evidence that elevated BHB levels and active HOPX are associated with reduced intestinal epithelial proliferation in humans. This study thus identifies a BHB-triggered pathway regulating intestinal tumorigenesis and indicates that oral or systemic interventions with a single metabolite may complement current prevention and treatment strategies for CRC.

A Pattern-based Pathology Approach to Very Early-onset Inflammatory Bowel Disease: Thinking Beyond Crohn Disease and Ulcerative Colitis

Very early-onset inflammatory bowel disease (VEO-IBD), IBD diagnosed in children younger than 6 years old, is phenotypically and genetically distinct from older onset IBD. Monogenic and digenic causative defects, particularly in primary immunodeficiency and intestinal epithelial barrier genes, have been identified in a subset of patients with VEO-IBD allowing for targeted therapies and improved outcomes. However, these findings are the minority, thus strategies to correctly diagnose patients, including identification of specific histopathologic findings with correlating clinical and laboratory features may provide critical and necessary insight into mechanisms of disease pathogenesis and subsequent therapeutic options. In this article, we review the pathologic findings seen in patients with VEO-IBD and outline a pattern-based approach to diagnosis using examples from primary immunodeficiencies with gastrointestinal manifestations.

Variants in STXBP3 are Associated with Very Early Onset Inflammatory Bowel Disease, Bilateral Sensorineural Hearing Loss and Immune Dysregulation

BACKGROUND AND AIMS

Very early onset inflammatory bowel disease [VEOIBD] is characterized by intestinal inflammation affecting infants and children less than 6 years of age. To date, over 60 monogenic aetiologies of VEOIBD have been identified, many characterized by highly penetrant recessive or dominant variants in underlying immune and/or epithelial pathways. We sought to identify the genetic cause of VEOIBD in a subset of patients with a unique clinical presentation.

METHODS

Whole exome sequencing was performed on five families with ten patients who presented with a similar constellation of symptoms including medically refractory infantile-onset IBD, bilateral sensorineural hearing loss and, in the majority, recurrent infections. Genetic aetiologies of VEOIBD were assessed and Sanger sequencing was performed to confirm novel genetic findings. Western analysis on peripheral blood mononuclear cells and functional studies with epithelial cell lines were employed.

RESULTS

In each of the ten patients, we identified damaging heterozygous or biallelic variants in the Syntaxin-Binding Protein 3 gene [STXBP3], a protein known to regulate intracellular vesicular trafficking in the syntaxin-binding protein family of molecules, but not associated to date with either VEOIBD or sensorineural hearing loss. These mutations interfere with either intron splicing or protein stability and lead to reduced STXBP3 protein expression. Knock-down of STXBP3 in CaCo2 cells resulted in defects in cell polarity.

CONCLUSION

Overall, we describe a novel genetic syndrome and identify a critical role for STXBP3 in VEOIBD, sensorineural hearing loss and immune dysregulation.

Deficiency in X-linked inhibitor of apoptosis protein promotes susceptibility to microbial triggers of intestinal inflammation

Inflammatory bowel disease (IBD) is characterized by inappropriate immune responses to the microbiota in genetically susceptible hosts, but little is known about the pathways that link individual genetic alterations to microbiota-dependent inflammation. Here, we demonstrated that the loss of X-linked inhibitor of apoptosis protein (XIAP), a gene associated with Mendelian IBD, rendered Paneth cells sensitive to microbiota-, tumor necrosis factor (TNF)–, receptor-interacting protein kinase 1 (RIPK1)–, and RIPK3-dependent cell death. This was associated with deficiency in Paneth cell–derived antimicrobial peptides and alterations in the stratification and composition of the microbiota. Loss of XIAP was not sufficient to elicit intestinal inflammation but provided susceptibility to pathobionts able to promote granulomatous ileitis, which could be prevented by administration of a Paneth cell–derived antimicrobial peptide. These data reveal a pathway critical for host-microbial cross-talk, which is required for intestinal homeostasis and the prevention of inflammation and which is amenable to therapeutic targeting.

Deficiency in X-linked inhibitor of apoptosis protein promotes susceptibility to microbial triggers of intestinal inflammation

Inflammatory bowel disease (IBD) is characterized by inappropriate immune responses to the microbiota in genetically susceptible hosts, but little is known about the pathways that link individual genetic alterations to microbiota-dependent inflammation. Here, we demonstrated that the loss of X-linked inhibitor of apoptosis protein (XIAP), a gene associated with Mendelian IBD, rendered Paneth cells sensitive to microbiota-, tumor necrosis factor (TNF)–, receptor-interacting protein kinase 1 (RIPK1)–, and RIPK3-dependent cell death. This was associated with deficiency in Paneth cell–derived antimicrobial peptides and alterations in the stratification and composition of the microbiota. Loss of XIAP was not sufficient to elicit intestinal inflammation but provided susceptibility to pathobionts able to promote granulomatous ileitis, which could be prevented by administration of a Paneth cell–derived antimicrobial peptide. These data reveal a pathway critical for host-microbial cross-talk, which is required for intestinal homeostasis and the prevention of inflammation and which is amenable to therapeutic targeting.

Clostridioides difficile Infection in Pediatric Inflammatory Bowel Disease: A Clinician's Dilemma

Clostridioides difficile infection (CDI) in children with inflammatory bowel disease (IBD) can present and manifest differently from the general population with CDI, and it can worsen the underlying disease course. Furthermore, current clinical assays used to test for CDI do not accurately distinguish between true CDI or colonization. This uncertainty leads to difficulty in identifying the etiology and therapy for symptomatic patients with IBD. Improved diagnostic tests, biomarkers, and safe and effective treatment options are greatly needed for this vulnerable population.

Pediatric Global Health in Children with Very Early-Onset Inflammatory Bowel Disease

OBJECTIVE 

Children with very early-onset inflammatory bowel disease (VEO-IBD) represent a distinct group of patients with IBD with unique phenotypic and genetic characteristics; however, they are frequently omitted from psychosocial research. This study used a novel, brief measure of pediatric global health to assess (1) overall health-related quality of life (HRQOL) in children with VEO-IBD, (2) HRQOL compared to healthy children, and (3) whether gastrointestinal symptoms account for the differences in HRQOL between these groups.

METHODS 

Caregivers of 51 children with VEO-IBD (Mage = 4.26 years, 75% male) and 54 healthy children (Mage = 3.50 years, 54% male) completed the PROMIS Pediatric Global Health Scale (PGH-7) parent-proxy form to assess HRQOL and a questionnaire assessing gastrointestinal symptoms. Descriptive statistics, analysis of variance with covariates (ANCOVA), and meditation analyses with bootstrapping were conducted.

RESULTS 

Caregivers of children with VEO-IBD rated their HRQOL as relatively positive, although children with greater disease yielded lower ratings on some PGH-7 items (e.g., fun with friends, physical health, sadness). Compared to healthy youth, children with VEO-IBD scored lower on the PGH-7, with significantly lower item-level scores on overall health, physical health, mental health, and quality of life. Gastrointestinal symptoms mediated the association between health status (i.e., VEO-IBD vs. healthy) and HRQOL, αβ = -2.84, 95% CI = -5.70, -0.34.

CONCLUSIONS 

While some children with VEO-IBD are at risk for deficits in HRQOL, many are quite resilient. Psychosocial screening is necessary for providing appropriate referrals to behavioral health services and learning more about psychosocial adjustment in children with VEO-IBD.

Immune Dysregulation in Human ITCH Deficiency Successfully Treated with Hematopoietic Cell Transplantation

BACKGROUND

Mutations in ITCH, which encodes an E3 ubiquitin-protein ligase, can result in systemic autoimmunity and immunodeficiency. The clinical phenotype and mechanism of disease have not been fully characterized, resulting in a paucity of therapeutic options for this potentially fatal disease.

OBJECTIVE

We aimed to (1) expand the understanding about the phenotype of human ITCH deficiency (2) further characterize the associated immune dysregulation, and (3) report the first successful hematopoietic cell transplant (HCT) in a patient with ITCH deficiency.

METHODS

Disease profiling was performed in a patient with multisystem immune dysregulation. Whole exome sequencing with trio analysis and functional validation of candidate disease variants were performed, including mRNA and protein expression. Analyses to further delineate the immunophenotype included quantitative evaluation of lymphoid and myeloid subsets with flow cytometry and mass cytometry.

RESULTS

A patient with multisystem immune dysregulation presenting with growth failure, very-early-onset inflammatory bowel disease, arthritis, uveitis, psoriasis, and type 1 diabetes mellitus underwent whole exome sequencing, which identified novel compound heterozygous mutations in ITCH. Reduced expression of ITCH mRNA and absent ITCH protein were found. Abnormalities in both lymphoid and myeloid lineages were identified. The patient underwent HCT. He demonstrated excellent immune reconstitution and resolution of many manifestations of his systemic disease.

CONCLUSIONS

Here we report ITCH deficiency with unique clinical features of colonic very-early-onset inflammatory bowel disease, arthritis, and uveitis in the setting of immune dysregulation and further characterize the underlying immune dysregulation. We demonstrate that HCT can be an effective, and potentially curative, therapy for ITCH deficiency.

Importance of early detection of infantile inflammatory bowel disease with defective IL-10 pathway: A case report

RATIONALE

Infantile inflammatory bowel disease (IBD) is an extremely rare subgroup of IBD that includes patients whose age of onset is younger than 2 years old. These patients can have more surgical interventions, and a severe and refractory disease course with higher rates of conventional treatment failure. Monogenic defects play an important role in this subgroup of IBD, and identification of the underlying defect can guide the therapeutic approach.

PATIENT CONCERNS

In 2007, a 4-month-old girl from a nonconsanguineous family presenting with anal fistula, chronic diarrhea, and failure to thrive. She underwent multiple surgical repairs but continued to have persistent colitis and perianal fistulas.

DIAGNOSIS

Crohn's disease was confirmed by endoscopic and histologic finding.

INTERVENTION

Conventional pediatric IBD therapy including multiple surgical interventions and antitumor necrosis factor alpha agents were applied.

OUTCOMES

The patient did not respond to conventional pediatric IBD therapy. Interleukin-10 (IL-10) receptor mutation was discovered by whole-exome sequencing and defective IL-10 signaling was proved by functional test of IL-10 signaling pathway by the age of 12. The patient is currently awaiting hematopoietic stem cell transplantation.

LESSONS

Early detection of underlying genetic causes of patients with infantile-IBD is crucial, since it may prevent patients from undergoing unnecessary surgeries and adverse effects from ineffective medical therapies. Moreover, infantile-IBD patients with complex perianal disease, intractable early onset enterocolitis and extraintestinal manifestations including oral ulcers and skin folliculitis, should undergo genetic and functional testing for IL-10 pathway defect.

Colonoids From Patients With Pediatric Inflammatory Bowel Disease Exhibit Decreased Growth Associated With Inflammation Severity and Durable Upregulation of Antigen Presentation Genes

BACKGROUND

Defining epithelial cell contributions to inflammatory bowel disease (IBD) is essential for the development of much needed therapies for barrier repair. Children with very early onset (VEO)-IBD have more extensive, severe, and refractory disease than older children and adults with IBD and, in some cases, have defective barrier function. We therefore evaluated functional and transcriptomic differences between pediatric IBD (VEO and older onset) and non-IBD epithelium using 3-dimensional, biopsy-derived organoids.

METHODS

We measured growth efficiency relative to histopathological and clinical parameters in patient enteroid (ileum) and colonoid (colon) lines. We performed RNA-sequencing on patient colonoids and subsequent flow cytometry after multiple passages to evaluate changes that persisted in culture.

RESULTS

Enteroids and colonoids from pediatric patients with IBD exhibited decreased growth associated with histological inflammation compared with non-IBD controls. We observed increased LYZ expression in colonoids from pediatric IBD patients, which has been reported previously in adult patients with IBD. We also observed upregulation of antigen presentation genes HLA-DRB1 and HLA-DRA, which persisted after prolonged passaging in patients with pediatric IBD.

CONCLUSIONS

We present the first functional evaluation of enteroids and colonoids from patients with VEO-IBD and older onset pediatric IBD, a subset of which exhibits poor growth. Enhanced, persistent epithelial antigen presentation gene expression in patient colonoids supports the notion that epithelial cell-intrinsic differences may contribute to IBD pathogenesis.

Dynamics of the Stool Virome in Very Early-Onset Inflammatory Bowel Disease

BACKGROUND AND AIMS

Dysbiosis of the gut microbiota is a well-known correlate of the pathogenesis of inflammatory bowel disease [IBD]. However, few studies have examined the microbiome in very early-onset [VEO] IBD, which is defined as onset of IBD before 6 years of age. Here we focus on the viral portion of the microbiome-the virome-to assess possible viral associations with disease processes, reasoning that any viruses potentially associated with IBD might grow more robustly in younger subjects, and so be more detectable.

METHODS

Virus-like particles [VLPs] were purified from stool samples collected from patients with VEO-IBD [n = 54] and healthy controls [n = 23], and characterized by DNA and RNA sequencing and VLP particle counts.

RESULTS

The total number of VLPs was not significantly different between VEO-IBD and healthy controls. For bacterial viruses, the VEO-IBD subjects were found to have a higher ratio of Caudovirales vs to Microviridae compared to healthy controls. An increase in Caudovirales was also associated with immunosuppressive therapy. For viruses infecting human cells, Anelloviridae showed higher prevalence in VEO-IBD compared to healthy controls. Within the VEO-IBD group, higher levels of Anelloviridae DNA were also positively associated with immunosuppressive treatment. To search for new viruses, short sequences enriched in VEO-IBD samples were identified, and some could be validated in an independent cohort, although none was clearly viral; this provides sequence tags to interrogate in future studies.

CONCLUSIONS

These data thus document perturbations to normal viral populations associated with VEO-IBD, and provide a biomarker-Anelloviridae DNA levels-potentially useful for reporting the effectiveness of immunosuppression.

The Treatment of Pediatric Inflammatory Bowel Disease with Biologic Therapies

PURPOSE OF REVIEW

Biologics for the treatment of inflammatory bowel disease (IBD) have been transformative to the therapeutic goals in the pediatric population. We review the biologics used to treat IBD, highlighting the importance of patient selection, dosing considerations, and therapeutic drug monitoring in children.

RECENT FINDINGS

Infliximab is well-established as a safe and efficacious therapy for Crohn's disease and ulcerative colitis. Both dose escalation strategies and therapeutic drug monitoring increase the likelihood of response to anti-TNFα therapies. Early real-world experience of vedolizumab and ustekinumab in pediatric IBD shows promising results, including clinical response rates comparable to what is seen in adults, but there are limited data using them as first-line therapies. Biologic therapies have improved outcomes in pediatric IBD, including achieving mucosal healing as well as improved growth and pubertal development. Therapeutic drug monitoring improves likelihood of response to anti-TNFα therapies, but further studies for vedolizumab and ustekinumab are necessary.

The Unique Disease Course of Children with Very Early onset-Inflammatory Bowel Disease

BACKGROUND

Insight into the pathogenesis of very early onset-inflammatory bowel disease (VEO-IBD) has expanded through the identification of causative monogenic defects detected in a subset of patients. However, the clinical course of this population remains uncertain. The study objective is to determine whether VEO-IBD is associated with more severe disease, defined as increased surgical intervention and growth failure, than older pediatric IBD. Secondary outcomes included therapeutic response and hospitalizations.

METHODS

Subjects with IBD diagnosed younger than 6 years old (VEO-IBD) were compared with children diagnosed 6 to 10 (intermediate-onset) and older than 10 years of age (older-onset IBD). Metadata obtained from the medical record included age of onset, disease phenotype and location, surgeries, medical therapy, and comorbid conditions. Length of follow-up was at least 1 year from diagnosis.

RESULTS

There were 229, 221, and 521 subjects with VEO, intermediate-onset, and older-onset IBD, respectively. Very early onset-inflammatory bowel disease subjects underwent more diverting ileostomies (P < 0.001) and colectomies (P < 0.001) than the older children. There was less improvement in weight- and height-for-age Z scores during the follow-up period in subjects with VEO-IBD. Additionally, subjects with VEO-IBD had higher rates of medication failure at 1 year and were more frequently readmitted to the hospital. Targeted therapy was successfully used almost exclusively in VEO-IBD.

CONCLUSION

Patients with VEO-IBD can have a more severe disease course with increased surgical interventions and poor growth as compared with older-onset IBD patients. Further, VEO-IBD patients are more likely to be refractory to conventional therapies. Strategies using targeted therapy in these children can improve outcome and, in some cases, be curative.

North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Position Paper on the Evaluation and Management for Patients With Very Early-onset Inflammatory Bowel Disease

The rate of pediatric inflammatory bowel disease (IBD) has been increasing over the last decade and this increase has occurred most rapidly in the youngest children diagnosed <6 years, known as very early-onset inflammatory bowel disease (VEO-IBD). These children can present with more extensive and severe disease than older children and adults. The contribution of host genetics in this population is underscored by the young age of onset and the distinct, aggressive phenotype. In fact, monogenic defects, often involving primary immunodeficiency genes, have been identified in children with VEO-IBD and have led to targeted and life-saving therapy. This position paper will discuss the phenotype of VEO-IBD and outline the approach and evaluation for these children and what factors should trigger concern for an underlying immunodeficiency. We will then review the immunological assays and genetic studies that can facilitate the identification of the underlying diagnosis in patients with VEO-IBD and how this evaluation may lead to directed therapies. The position paper will also aid the pediatric gastroenterologist in recognizing when a patient should be referred to a center specializing in the care of these patients. These guidelines are intended for pediatricians, allied health professionals caring for children, pediatric gastroenterologists, pediatric pathologists, and immunologists.

Early-Onset Inflammatory Bowel Disease

The epidemiology of inflammatory bowel disease has changed over the past 4 decades. The incidence is rising dramatically and the age of onset has become younger. This changing landscape of inflammatory bowel disease reflects the new recognition that the youngest children with inflammatory bowel disease are enriched in cases with underlying primary immunodeficiency and monogenic causes. The management of these cases can be quite different, with specific genetic etiologies supporting unique interventions and some requiring hematopoietic cell transplantation for effective treatment.

Efficacy of Combination Antibiotic Therapy for Refractory Pediatric Inflammatory Bowel Disease

BACKGROUND

Recent studies have shown that oral combination antibiotics may improve disease course in refractory inflammatory bowel disease (IBD). Here, we describe the use of combination oral antibiotics as salvage therapy in refractory ulcerative colitis (UC), Crohn's colitis, and IBD-unclassified (IBD-U) at a large pediatric IBD center.

METHODS

Clinical response, disease activity indices, adverse events, and clinical outcomes were measured up to 1 year after antibiotic treatment in this retrospective cohort study of children with medically refractory IBD colitis.

RESULTS

Sixty-three patients with refractory UC, Crohn's colitis, and IBD-U (median age [interquartile range {IQR}], 15.3 [11.2-16.5] years; median disease duration [IQR], 1.2 [0.41-4.6] years) received a combination of 3 or 4 oral antibiotics (most commonly amoxicillin, metronidazole, and either doxycycline or ciprofloxacin) for a median (IQR) of 29 (21-58) days. Thirty-four patients (54%) were deemed corticosteroid-refractory or -dependent, with the majority (62/63) having a previous or present loss of response or primary nonresponse to anti-tumor necrosis factor alpha (anti-TNFα) therapy. Use of combination antibiotics led to a significant decrease in median Pediatric Ulcerative Colitis Activity Index (PUCAI) score (IQR) from 55 (40-65) to 10 (0-40; P < 0.0001) over 3 ± 1 weeks, with 25/63 (39.7%) patients achieving clinical remission (PUCAI <10 points). The clinical benefits of oral antibiotics were independent of anti-TNFα therapy optimization. Among children entering clinical remission (n = 25), only 1 patient required surgery at 1-year follow-up, vs 10 patients in the nonresponder group. Negative predictors of response to combination antibiotics were exposure to doxycycline (odds ratio [OR], 0.25; 95% CI, 0.08-0.76) and PUCAI ≥65 at baseline (OR, 0.2; 95% CI, 0.05-0.74).

CONCLUSIONS

Oral combination antibiotics appears to be an effective rescue and steroid-sparing therapy to induce remission in the short term in patients failing a biologic.

A novel human IL2RB mutation results in T and NK cell-driven immune dysregulation

A novel homozygous mutation in human IL2RB results in decreased IL-2Rβ protein expression and dysregulated IL-2/15 signaling. This hypomorphic mutation leads to decreased regulatory T cell frequency and an abnormal NK cell compartment, with clinical manifestations of autoimmunity and susceptibility to CMV.

The pleiotropic actions of interleukin-2 (IL-2) are essential for regulation of immune responses and maintenance of immune tolerance. The IL-2 receptor (IL-2R) is composed of IL-2Rα, IL-2Rβ, and IL-2Rγ subunits, with defects in IL-2Rα and IL-2Rγ and their downstream signaling effectors resulting in known primary immunodeficiency disorders. Here, we report the first human defect in IL-2Rβ, occurring in two infant siblings with a homozygous IL2RB mutation in the WSXWS motif, manifesting as multisystem autoimmunity and susceptibility to CMV infection. The hypomorphic mutation results in diminished IL-2Rβ surface expression and dysregulated IL-2/15 signaling, with an anticipated reduction in regulatory T cells. However, in contrast to the IL-2Rβ^−/− animal model, which lacks NK cells, these siblings demonstrate an expansion of NK cells, particularly the CD56^bright subset, and a lack of terminally differentiated NK cells. Thus, the early-onset autoimmunity and immunodeficiency are linked to functional deficits arising from altered IL-2Rβ expression and signaling in T and NK cells.

Genomic and Immunologic Drivers of Very Early-Onset Inflammatory Bowel Disease

PURPOSE OF REVIEW

Inflammatory bowel disease (IBD) is a multifactorial disease caused by dysregulated immune responses to commensal or pathogenic intestinal microbes, resulting in chronic intestinal inflammation. However, a subset of patients with IBD diagnosed <6 years of age, known as very early-onset (VEO)-IBD, can be phenotypically and genetically distinct from older onset IBD. We aim to review the clinical presentation of children with VEO-IBD and recent discoveries that point to the underlying genomic and immunologic drivers of disease, and the significant impact on our therapeutic decisions.

RECENT FINDINGS

VEO-IBD is increasing in incidence and is associated with more severe disease, aggressive progression, and poor response to most conventional therapies. This article will review some of the genetic findings in this population and the subsequent impact on therapy, with targeted approaches.

SUMMARY

Children with VEO-IBD may present with a different phenotype and more severe disease than older children and adults. An integrated approach combining genetics, immunology, and traditional IBD evaluations can lead to the identification of causal defects that directly impact management. These strategies can also be employed in older onset refractory IBD.

Inflammatory Bowel Disease in Primary Immunodeficiencies

PURPOSE OF REVIEW

Inflammatory bowel disease is most often a polygenic disorder with contributions from the intestinal microbiome, defects in barrier function, and dysregulated host responses to microbial stimulation. There is, however, increasing recognition of single gene defects that underlie a subset of patients with inflammatory bowel disease, particularly those with early-onset disease, and this review focuses on the primary immunodeficiencies associated with early-onset inflammatory bowel disease.

RECENT FINDINGS

The advent of next-generation sequencing has led to an improved recognition of single gene defects underlying some cases of inflammatory bowel disease. Among single gene defects, immune response genes are the most frequent category identified. This is also true of common genetic variants associated with inflammatory bowel disease, supporting a pivotal role for host responses in the pathogenesis. This review focuses on practical aspects related to diagnosis and management of children with inflammatory bowel disease who have underlying primary immunodeficiencies.

Diverting Ileostomy for the Treatment of Severe, Refractory, Pediatric Inflammatory Bowel Disease

OBJECTIVES

Diverting ileostomy is used as a temporizing therapy in patients with perianal Crohn disease; however, little data exist regarding its use for colonic disease. The primary aim of the present study was to determine the role of diversion in severe refractory colonic inflammatory bowel disease (IBD) in a pediatric population.

METHODS

Retrospective study of patients who underwent diverting ileostomy at The Children's Hospital of Philadelphia from 2000 to 2014 for the management of severe, refractory colonic IBD. Clinical variables were compared in the 1 year before ileostomy and 1 year after diversion. Surgical and disease outcomes including changes in diagnosis were reviewed through 2015.

RESULTS

Twenty-four patients underwent diverting ileostomy for refractory colonic disease. Initial diagnoses were Crohn disease in 10 (42%), ulcerative colitis in 1 (4%), and IBD-unclassified in 13 patients (54%). Comparing data before and after surgery, there were statistically significant improvements in height and weight velocities, height velocity z score, blood transfusion requirement, hemoglobin, and hospitalization rates. Chronic steroid use decreased from 71% to 22%. At the conclusion of the study, 10 patients had undergone subsequent colectomy, 7 had successful bowel reanastomosis, and 7 remain diverted. Seven patients (29%) had a change in diagnosis. There were 13 surgical complications in 7 subjects, including prolapse reduction, stoma revision, and resection of ischemic bowel.

CONCLUSIONS

In pediatric patients with refractory colonic IBD, diverting ileostomy can be a successful intervention to induce clinical stability. Importantly, diversion is a steroid-sparing therapy and allows additional time to clarify the diagnosis.

Ultrasound and MRI predictors of surgical bowel resection in pediatric Crohn disease

BACKGROUND

Imaging predictors for surgery in children with Crohn disease are lacking.

OBJECTIVE

To identify imaging features of the terminal ileum on short-interval bowel ultrasound (US) and MR enterography (MRE) in children with Crohn disease requiring surgical bowel resection and those managed by medical therapy alone.

MATERIALS AND METHODS

This retrospective study evaluated patients 18 years and younger with Crohn disease undergoing short-interval bowel US and MRE (within 2 months of one another), as well as subsequent ileocecectomy or endoscopy within 3 months of imaging. Appearance of the terminal ileum on both modalities was compared between surgical patients and those managed with medical therapy, with the following parameters assessed: bowel wall thickness, mural stratification, vascularity, fibrofatty proliferation, abscess, fistula and stricture on bowel US; bowel wall thickness, T2 ratio, enhancement pattern, mesenteric edema, fibrofatty proliferation, abscess, fistula and stricture on MRE. A two-sided t-test was used to compare means, a Mann-Whitney U analysis was used for non-parametric parameter scores, and a chi-square or two-sided Fisher exact test compared categorical variables. Imaging findings in surgical patients were correlated with location-matched histopathological scores of inflammation and fibrosis using a scoring system adapted from the Simple Endoscopic Score for Crohn Disease, and a Spearman rank correlation coefficient was used to compare inflammation and fibrosis on histopathology.

RESULTS

Twenty-two surgical patients (mean age: 16.5 years; male/female: 13/9) and 20 nonsurgical patients (mean age: 14.8; M/F: 8/12) were included in the final analysis. On US, the surgical group demonstrated significantly increased mean bowel wall thickness (6.1 mm vs. 4.7 mm for the nonsurgical group; P = 0.01), loss of mural stratification (odds ratio [OR] = 6.3; 95% confidence interval [CI]: 1.4-28.4; P = 0.02) and increased fibrofatty proliferation (P = 0.04). On MRE, the surgical group showed increased mean bowel wall thickness (9.1 mm vs. 7.2 mm for the nonsurgical group; P = 0.02), increased mean T2 ratio (4.6 vs. 3.6 for the nonsurgical group; P = 0.03), different enhancement patterns (P = 0.03), increased mesenteric edema (P = 0.001) and increased stricture formation (OR = 8.2; 95% CI: 1.8-36.4; P = 0.005). Nineteen of 22 ileocecectomy specimens showed severe inflammation and 21/22 showed severe fibrosis, with significant correlation between inflammation and fibrosis scores (ρ = 0.55; P = 0.008); however, correlation with imaging findings was limited by the uniformity of findings on histopathology.

CONCLUSION

Children with terminal ileal Crohn disease requiring surgical bowel resection demonstrate more severe manifestations of imaging features traditionally associated with both active inflammation and chronic fibrosis than those managed medically on US and MRE, findings that are corroborated by histopathology. These features may potentially serve as imaging biomarkers indicating the necessity for surgical intervention.

Genomic Alterations Observed in Colitis-Associated Cancers Are Distinct From Those Found in Sporadic Colorectal Cancers and Vary by Type of Inflammatory Bowel Disease

BACKGROUND & AIMS

Patients with inflammatory bowel diseases, such as Crohn's disease (CD) and ulcerative colitis (UC), are at increased risk for small bowel or colorectal cancers (colitis-associated cancers [CACs]). We compared the spectrum of genomic alterations in CACs with those of sporadic colorectal cancers (CRCs) and investigated differences between CACs from patients with CD vs UC.

METHODS

We studied tumor tissues from patients with CACs treated at Memorial Sloan Kettering Cancer Center or Weill Cornell Medical College from 2003 through 2015. We performed hybrid capture-based next-generation sequencing analysis of >300 cancer-related genes to comprehensively characterize genomic alterations.

RESULTS

We performed genomic analyses of 47 CACs (from 29 patients with UC and 18 with CD; 43 primary tumors and 4 metastases). Primary tumors developed in the ileum (n = 2), right colon (n = 18), left colon (n = 6), and rectosigmoid or rectum (n = 21). We found genomic alterations in TP53, IDH1, and MYC to be significantly more frequent, and mutations in APC to be significantly less frequent, than those reported in sporadic CRCs by The Cancer Genome Atlas or Foundation Medicine. We identified genomic alterations that might be targeted by a therapeutic agent in 17 of 47 (36%) CACs. These included the mutation encoding IDH1 R132; amplification of FGFR1, FGFR2, and ERBB2; and mutations encoding BRAF V600E and an EML4-ALK fusion protein. Alterations in IDH1 and APC were significantly more common in CACs from patients with CD than UC.

CONCLUSIONS

In an analysis of CACs from 47 patients, we found significant differences in the spectrum of genomic alterations in CACs compared with sporadic CRCs. We observed a high frequency of IDH1 R132 mutations in patients with CD but not UC, as well as a high frequency of MYC amplification in CACs. Many genetic alterations observed in CACs could serve as therapeutic targets.

A de novo whole gene deletion of XIAP detected by exome sequencing analysis in very early onset inflammatory bowel disease: a case report

Background

Children with very early-onset inflammatory bowel disease (VEO-IBD), those diagnosed at less than 5 years of age, are a unique population. A subset of these patients present with a distinct phenotype and more severe disease than older children and adults. Host genetics is thought to play a more prominent role in this young population, and monogenic defects in genes related to primary immunodeficiencies are responsible for the disease in a small subset of patients with VEO-IBD.

Case Presentation

We report a child who presented at 3 weeks of life with very early-onset inflammatory bowel disease (VEO-IBD). He had a complicated disease course and remained unresponsive to medical and surgical therapy. The refractory nature of his disease, together with his young age of presentation, prompted utilization of whole exome sequencing (WES) to detect an underlying monogenic primary immunodeficiency and potentially target therapy to the identified defect. Copy number variation analysis (CNV) was performed using the eXome-Hidden Markov Model. Whole exome sequencing revealed 1,380 nonsense and missense variants in the patient. Plausible candidate variants were not detected following analysis of filtered variants, therefore, we performed CNV analysis of the WES data, which led us to identify a de novo whole gene deletion in XIAP.

Conclusion

This is the first reported whole gene deletion in XIAP, the causal gene responsible for XLP2 (X-linked lymphoproliferative Disease 2). XLP2 is a syndrome resulting in VEO-IBD and can increase susceptibility to hemophagocytic lymphohistocytosis (HLH). This identification allowed the patient to be referred for bone marrow transplantation, potentially curative for his disease and critical to prevent the catastrophic sequela of HLH. This illustrates the unique etiology of VEO-IBD, and the subsequent effects on therapeutic options. This cohort requires careful and thorough evaluation for monogenic defects and primary immunodeficiencies.

Exome sequencing analysis reveals variants in primary immunodeficiency genes in patients with very early onset inflammatory bowel disease

BACKGROUND & AIMS

Very early onset inflammatory bowel disease (VEO-IBD), IBD diagnosed at 5 years of age or younger, frequently presents with a different and more severe phenotype than older-onset IBD. We investigated whether patients with VEO-IBD carry rare or novel variants in genes associated with immunodeficiencies that might contribute to disease development.

METHODS

Patients with VEO-IBD and parents (when available) were recruited from the Children's Hospital of Philadelphia from March 2013 through July 2014. We analyzed DNA from 125 patients with VEO-IBD (age, 3 wk to 4 y) and 19 parents, 4 of whom also had IBD. Exome capture was performed by Agilent SureSelect V4, and sequencing was performed using the Illumina HiSeq platform. Alignment to human genome GRCh37 was achieved followed by postprocessing and variant calling. After functional annotation, candidate variants were analyzed for change in protein function, minor allele frequency less than 0.1%, and scaled combined annotation-dependent depletion scores of 10 or less. We focused on genes associated with primary immunodeficiencies and related pathways. An additional 210 exome samples from patients with pediatric IBD (n = 45) or adult-onset Crohn's disease (n = 20) and healthy individuals (controls, n = 145) were obtained from the University of Kiel, Germany, and used as control groups.

RESULTS

Four hundred genes and regions associated with primary immunodeficiency, covering approximately 6500 coding exons totaling more than 1 Mbp of coding sequence, were selected from the whole-exome data. Our analysis showed novel and rare variants within these genes that could contribute to the development of VEO-IBD, including rare heterozygous missense variants in IL10RA and previously unidentified variants in MSH5 and CD19.

CONCLUSIONS

In an exome sequence analysis of patients with VEO-IBD and their parents, we identified variants in genes that regulate B- and T-cell functions and could contribute to pathogenesis. Our analysis could lead to the identification of previously unidentified IBD-associated variants.

Immune tolerance. Group 3 innate lymphoid cells mediate intestinal selection of commensal bacteria-specific CD4⁺ T cells

Inflammatory CD4(+) T cell responses to self or commensal bacteria underlie the pathogenesis of autoimmunity and inflammatory bowel disease (IBD), respectively. Although selection of self-specific T cells in the thymus limits responses to mammalian tissue antigens, the mechanisms that control selection of commensal bacteria-specific T cells remain poorly understood. Here, we demonstrate that group 3 innate lymphoid cell (ILC3)-intrinsic expression of major histocompatibility complex class II (MHCII) is regulated similarly to thymic epithelial cells and that MHCII(+) ILC3s directly induce cell death of activated commensal bacteria-specific T cells. Further, MHCII on colonic ILC3s was reduced in pediatric IBD patients. Collectively, these results define a selection pathway for commensal bacteria-specific CD4(+) T cells in the intestine and suggest that this process is dysregulated in human IBD.

Impact of exome sequencing in inflammatory bowel disease

Approaches to understanding the genetic contribution to inflammatory bowel disease (IBD) have continuously evolved from family- and population-based epidemiology, to linkage analysis, and most recently, to genome-wide association studies (GWAS). The next stage in this evolution seems to be the sequencing of the exome, that is, the regions of the human genome which encode proteins. The GWAS approach has been very fruitful in identifying at least 163 loci as being associated with IBD, and now, exome sequencing promises to take our genetic understanding to the next level. In this review we will discuss the possible contributions that can be made by an exome sequencing approach both at the individual patient level to aid with disease diagnosis and future therapies, as well as in advancing knowledge of the pathogenesis of IBD.

The gut microbiota, environment and diseases of modern society

The human gut microbiota is a complex community that provides important metabolic functions to the host. Consequently, alterations in the gut microbiota have been associated with the pathogenesis of several human diseases associated with a disturbance in metabolism, particularly those that have been increasing in incidence over the last several decades including obesity, diabetes and atherosclerosis. In this review, we explore how advances in deep DNA sequencing technology have provided us a greater understanding of the factors that influence that composition of the gut microbiota and its possible links to the pathogenesis of these diseases.

Recurrence rate of clostridium difficile infection in hospitalized pediatric patients with inflammatory bowel disease

BACKGROUND

The incidence and associated morbidity of Clostridium difficile (CD) infection has been increasing at an alarming rate in North America. Clostridium difficile-associated diarrhea (CDAD) is the leading cause of nosocomial diarrhea in the USA. Patients with CDAD have longer average hospital admissions and additional hospital costs. Evidence has demonstrated that patients with inflammatory bowel disease (IBD) have a higher incidence of CD in comparison to the general population. The aim of this study was to compare the rate of recurrence of CD in hospitalized pediatric patients with IBD compared to hospitalized controls. The secondary aim was to evaluate whether infection with CD resulted in a more severe disease course of IBD.

METHODS

This was a nested case control retrospective study of hospitalized pediatric patients. Diagnosis of CD was confirmed with stool Toxin A and B analysis. The following data were obtained from the medical records: demographic information, classification of IBD including location of disease, IBD therapy, and prior surgeries. In addition, prior hospital admissions within 1 year and antibiotic exposure were recorded. The same information was recorded following CD infection. Cases were patients with IBD and CD; two control populations were also studied: patients with CD but without IBD, and patients with IBD but without CD.

RESULTS

For aim 1, a total of 111 eligible patients with IBD and CD infection and 77 eligible control patients with CD infection were included. The rate of recurrence of CD in the IBD population was 34% compared to 7.5% in the control population (P < 0.0001). In evaluating the effect of CD infection on IBD disease severity, we compared the 111 IBD patients with CD to a second control population of 127 IBD patients without CD. 57% of IBD-CD patients were readmitted with an exacerbation of disease within 6 months of infection with CD and 67% required escalation of therapy following CD infection, compared to 30% of IBD patients without CD (P < 0.001). Of the patients with IBD and CD, 44% of the cases were new-onset IBD, 63% were on immunosuppression therapy, and 33% were on gastric acid suppression prior to infection. In comparing the IBD-CD and control CD populations, there was no significant difference in antibiotic exposure: 33% of IBD patients and 26% of control patients were on antibiotics (P < 0.2). With regard to prior hospitalization, 10% of patients with IBD were hospitalized in the 30 days prior to infection in comparison to 27% of the control CD patients (P < 0.002).

CONCLUSIONS

CD infection in patients with IBD results in a higher rate of recurrence and is associated with higher morbidity than the general population. Patients with IBD often required hospitalization and escalation of therapy following infection with CD, suggesting that CD resulted in increased severity of IBD disease. In addition, IBD patients were more likely develop community-acquired CD, while the control patients developed nosocomial infections, indicating a higher susceptibility to CD infection in patients with IBD.

Phase I trial of sargramostim in pediatric Crohn's disease

BACKGROUND

Improving granulocyte function may represent an effective therapy for Crohn's disease (CD). We performed a Phase I-2 trial of sargramostim (SRG) in children with CD.

METHODS

This was multicenter, open-label study in 6-16-year-old patients with moderate to severely active CD. Patients received either 4 or 6 microg/kg SRG subcutaneously daily for 8 weeks, with and without concomitant corticosteroids (CS). The primary endpoint was identification of a safe and tolerable dose in children. The secondary endpoint was establishment of the pharmacokinetics (PK). Efficacy, a tertiary endpoint, was measured by the Pediatric CD Activity Index (PCDAI). Response was defined as a decrease from baseline of > or =12.5 points and remission as absolute PCDAI of < or =10.

RESULTS

In all, 22 patients were enrolled: 12 and 10 received 4 and 6 mg/kg, respectively; 19 completed the course. Both doses were found to be safe and well tolerated. Mild injection-site reactions occurred in 90% of patients. Three patients required dose reductions due to elevated absolute neutrophil counts. Following 4 microg/kg the mean area under the curve (AUC) was 2.64 and 2.80 ngh/mL for the 6-11- and 12-16-year-old groups, respectively. The mean half-life (t(1/2)) was 1.22 and 1.59 hours, respectively. Following 6 microg/kg, the mean AUC was 5.01 ngh/mL for the 12-16-year-old group, a 1.8-fold increase. A total of 16/18 patients (88%) achieved remission or response.

CONCLUSIONS

Sargramostim at both 4 and 6 mg/kg was well tolerated. PK analysis suggested dose proportionality unaffected by CS exposure. Remission and response data are encouraging, but further trials are needed to assess efficacy.