Serum infliximab concentrations in pediatric inflammatory bowel disease

Successful long-term treatment of paediatric ulcerative colitis with vedolizumab: a case report

Biologics are recommended to treat paediatric ulcerative colitis (UC) that is chronically active or steroid-dependent despite aminosalicylic acids (5-ASA) and thiopurine treatments. Anti-tumour necrosis factor inhibitors (Anti-TNF inhibitors) are the agents of choice and vedolizumab could be considered as second-line biologic therapy.In the current case, we aim to describe a successful long-term treatment with vedolizumab in a 9-year-old boy with severe UC and primary non-response to infliximab. Concomitant azathioprine was used, and steroid refractoriness was also detected. Drug and anti-drug antibody levels were negative after infliximab induction so a switch to a 6-week-induction vedolizumab regimen followed by a maintenance regimen as a monotherapy was decided. The clinical response and tolerability to vedolizumab allowed long-term disease remission. Vedolizumab is currently non-authorised to treat paediatric patients and there is limited data on long-term treatments to date. This case contributes to the literature by adding evidence on the long-term efficacy and safety of vedolizumab in paediatric UC.

Risk of consecutive immunogenic failure in switchers of anti-tumor necrosis factor alpha among patients with inflammatory bowel diseases

BACKGROUND

Evidence regarding the risk of immunogenicity in patients with inflammatory bowel disease (IBD) who switched anti-tumor necrosis factor alpha (anti-TNFα) therapies to a subsequent anti-TNFα (either infliximab or adalimumab) is conflicting. We aimed to assess the risk of consecutive immunogenicity to anti-TNFα in a large cohort of patients.

METHODS

This was a multicenter retrospective study. Medical records of adult and pediatric IBD switchers who had pharmacokinetic data for both agents between 2014 and 2020 were retrieved. Data including age, sex, disease type, duration of therapies, and concomitant use of immunomodulators (IMMs) were recorded.

RESULTS

Overall, 164 patients were included [52% female; 88% Crohn's disease; mean age = 24.4 ± 14.6 years; 108 (66%) switched from infliximab to adalimumab and 56 (34%) vice versa]; 120 (73.1%) patients switched due to an immunogenic failure. Among patients switching therapy from infliximab to adalimumab due to an immunogenic failure immunogenicity to infliximab was significantly associated with consecutive immunogenicity to adalimumab (p = 0.026). Forthy four out of 120 patients (36.6%) with an immunogenic failure to the first anti-TNFα started an IMM with the second anti-TNFα. This combination with IMM was not associated with reduction of consecutive immunogenicity (p = 0.31), but it was associated with longer drug retention (p = 0.007). Multivariate analysis demonstrated that older age at second anti-TNFα, adjusted to the chronology of therapy and sex, was associated with increased immunogenicity to the second anti-TNFα.

CONCLUSION

Patients with IBD who switch from infliximab to adalimumab following an immunogenic failure are at increased risk for consecutive immunogenicity to adalimumab. IMM use after a switch prolongs drug retention.

A population physiologically-based pharmacokinetic model to characterize antibody disposition in pediatrics and evaluation of the model using infliximab

AIMS

In order to better predict the pharmacokinetics (PK) of antibodies in children, and to facilitate dose optimization of antibodies in paediatric patients, there is a need to develop systems PK models that integrate ontogeny-related changes in human physiological parameters.

METHODS

A population-based physiological-based PK (PBPK) model to characterize antibody PK in paediatrics has been developed, by incorporating age-related changes in body weight, organ weight, organ blood flow rate and interstitial volumes in a previously published platform model. The model was further used to perform Monte Carlo simulations to investigate clearance vs. age and dose-exposure relationships for infliximab.

RESULTS

By estimating only one parameter and associated interindividual variability, the model was able to characterize clinical PK of infliximab from two paediatric cohorts (n = 141, 4-19 years) reasonably well. Model simulations demonstrated that only 50% of children reached desired trough concentrations when receiving FDA-labelled dosing regimen for infliximab, suggesting that higher doses and/or more frequent dosing are needed to achieve target trough concentrations of this antibody.

CONCLUSION

The paediatric PBPK model presented here can serve as a framework to characterize the PK of antibodies in paediatric patients. The model can also be applied to other protein therapeutics to advance precision medicine paradigm and optimize antibody dosing regimens in children.

Pharmacokinetics, Pharmacodynamics, and Immunogenicity of Infliximab in Pediatric Inflammatory Bowel Disease: A Systematic Review and Revised Dosing Considerations

OBJECTIVES

Infliximab (IFX), a monoclonal antibody directed against tumor necrosis factor alpha is a potent treatment option for inflammatory bowel disease (IBD). Dosing regimens in children are extrapolated from adult data using a fixed, weight-based dose, which is often not adequate. While clinical trials have focused on safety and efficacy, there is limited data on pharmacokinetic characteristics and immunogenicity of IFX in children. The objective was to provide a systematic overview of current literature on pharmacokinetic and immunogenicity of IFX in children with IBD, to assess the validity of current adult to pediatric dosing extrapolation.

METHODS

A literature search identified publications up to October 2018. Eligibility criteria were study population consisting of children and/or adolescents with IBD, report of IFX trough levels and/or antibodies-to IFX, full text article or abstract, article in English, and original data.

RESULTS

Initial electronic search yielded 2360 potentially relevant articles, with 1831 remaining after removal of duplicates. An additional search yielded another 202 potentially relevant articles. Of the 2033 retrieved articles, 2000 articles were excluded based on title, abstract, or eligibility criteria. Clearance of IFX was increased in young children and children with extensive disease, leading to lower trough levels after extrapolated dosing of 5 mg/kg, antibodies-to IFX emergence, and subsequent reduced efficacy.

CONCLUSIONS

Adult to pediatric weight-based dosing extrapolation is often inadequate. We provide several considerations for optimal dosing of IFX in children and adolescents with IBD.

Trough Levels of Infliximab at Week 6 Are Predictive of Remission at Week 14 in Pediatric Crohn's Disease

OBJECTIVE

Infliximab (IFX) is a frequent therapeutic option for Crohn disease (CD) patients. Early detection of responders to IFX is critical for the management of CD in order to avoid long-term exposure to the drug without benefit. This retrospective study aimed at analysing which early parameters recorded during the induction period are able to predict response to IFX during the maintenance period in pediatric CD.

PATIENTS AND METHODS

Medical records of all CD patients ages from 2 to 18 years who received IFX at a tertiary IBD center were retrospectively analyzed. Children were classified in 3 groups according to their response at week 14 (W14) remission, clinical response or , no response. The factors recorded at W0, W2, and W6, which were associated with remission at W14 were analyzed using a logistic regression.

RESULTS

Among the 111 patients included, 74.8% patients were responders to IFX at W14, including 38.7% in clinical remission and 36% with partial clinical response. Clinical remission at W14 was associated with normal growth (P < 0.01), and normal albuminemia (P = 0.01) at baseline, It was also associated with trough levels to IFX >8.3 μg/ml at week 6 (P < 0.01).

CONCLUSION

Trough levels to IFX >8.3 μg/ml at week 6 are predictive of remission at W14 for luminal disease.

Serum Infliximab Cutoff trough Level Values for Maintaining Hematological Remission in Pediatric Inflammatory Bowel Disease

Background/Aims

Infliximab (IFX) often loses its therapeutic effect in initial responders with inflammatory bowel disease (IBD) over time. Low serum IFX trough levels (TLs) are linked to poor clinical response and outcomes. Maintenance of optimal therapeutic IFX concentrations is important for sustaining response and achieving good clinical outcomes. Measurement of serum IFX TLs is helpful for determining a further proper therapeutic plan. However, adequate therapeutic IFX TLs in pediatric IBD is uncertain. We aimed to identify the cutoff values for IFX TLs associated with laboratory response to IFX maintenance therapy.

Methods

Patients with pediatric IBD who had received IFX infusions between December 2008 and March 2015 at Samsung Medical Center were retrospectively investigated. We analyzed 239 blood samples that were collected from 103 pediatric patients. We measured IFX TLs at induction (6 and 14 weeks) and during maintenance therapy (>22 weeks, 8 weeks interval) by fluid-phase radioimmunoassays.

Results

A significant association was found between the erythrocyte sedimentation rate (ESR) and IFX TLs during maintenance (correlation coefficient, -0.11; p=0.0005). A cutoff value of 18 mm/hr for ESR was used to define higher levels. Receiver operating characteristic analysis identified optimal cutoff values: IFX TL >1.58 µg/mL (sensitivity 82% and specificity 73%).

Conclusions

Cutoff values are considered a prerequisite for further investigating the clinical usefulness of measurements of IFX in patients maintained with IFX treatment.

Therapeutic Drug Monitoring and Outcome of Infliximab Therapy in Pediatric Onset Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) with pediatric onset has become more prevalent during past decades. Thus, the number of patients with moderate to severe disease subtype treated with antagonists to tumor necrosis factor alpha (TNFα) has concurrently risen. Most pediatric patients initially respond to these drugs but will need dose escalation during the first year of therapy. As pediatric data regarding therapeutic drug monitoring during therapy with TNFα-blocker adalimumab are sparse, this review focuses on the literature on therapeutic drug monitoring of infliximab and how it may guide management.

Physiologically-Based Pharmacokinetic Modeling vs. Allometric Scaling for the Prediction of Infliximab Pharmacokinetics in Pediatric Patients

The comparative performances of physiologically‐based pharmacokinetic (PBPK) modeling and allometric scaling for predicting the pharmacokinetics (PKs) of large molecules in pediatrics are unknown. Therefore, both methods were evaluated for accuracy in translating knowledge of infliximab PKs from adults to children. PBPK modeling was performed using the base model for large molecules in PK‐Sim version 7.4 with modifications in Mobi. Eight population PK models from literature were reconstructed and scaled by allometry to pediatrics. Evaluation data included seven pediatric studies (~4–18 years). Both methods performed comparably with 66.7% and 68.6% of model‐predicted concentrations falling within twofold of the observed concentrations for PBPK modeling and allometry, respectively. Considerable variability was noted among the allometric models. Therefore, pediatric clinical trial planning would benefit from using approaches that require predictions depending on the specific question i.e., PBPK modeling and allometry.

Therapeutic drug monitoring to improve outcome of anti-TNF drugs in pediatric inflammatory bowel disease

Introduction: Medical treatment of pediatric inflammatory bowel diseases (IBD) has been greatly changed by the introduction of a number of biologic agents that are able to target various players of the immune response. In particular, monoclonal antibodies against the pro-inflammatory cytokine TNF-alpha (TNF) such as infliximab, adalimumab, and golimumab are now in the clinics both in induction and maintenance therapy, and several efforts are currently ongoing to optimize the use of these drugs in children. Areas covered: This review focuses on therapeutic drug monitoring (TDM) of anti-TNF levels and antidrug antibodies (ADAs), in IBD children. A revision of the analytical assays used for assessing anti-TNF plasma levels is also provided. Expert opinion: Although there is a consensus across studies that higher anti-TNF trough levels are associated with a better clinical outcome, and that early anti-TNF serum measurements could be predictive of long-term response, it is still not clear what the best predictive time of sampling is and what the ideal target drug plasma concentration to achieve. Indeed, there are a number of published studies, particularly in pediatric cohorts, limited by the population size analyzed and more prospective large studies are needed to examine the value of these predictive markers.

Efficacy and safety of infliximab in very early onset inflammatory bowel disease: a national comparative retrospective study

Background

Very few data regarding the use of infliximab in children with very early-onset inflammatory bowel disease (VEO-IBD) have been reported.

Objective

We aimed to assess the efficacy and the safety of infliximab in children with VEO-IBD compared with older children.

Methods

Children treated with infliximab were identified within the Italian IBD registry. The primary outcome was the rate of clinical remission at weeks 14 and 54. Secondary outcomes included the proportion of partial clinical response, treatment duration, and incidence of adverse events.

Results

Forty-two children with VEO-IBD were compared with 130 children with IBD. Despite significantly higher infliximab withdrawals in VEO-IBD patients during induction (42.9% vs 7.7% p < 0.01), remission rates at week 14 were similar (28.6% vs 43.8%, p = 0.10). At week 54 fewer VEO-IBD children were in remission (15.8% vs 54.3%, p < 0.01). The treatment duration was shorter in VEO-IBD (median 12.0 vs 18.4 months, p < 0.01). During the induction phase, adverse events were more common in the VEO-IBD group (p < 0.01).

Conclusion

Compared with older children, VEO-IBD patients have higher rates of infliximab failures, lower remission rates at one year, and more often experience adverse events during induction.

Higher Infliximab Trough Levels Are Associated With Better Outcome in Paediatric Patients With Inflammatory Bowel Disease

BACKGROUND

The role of therapeutic drug monitoring for infliximab [IFX] therapy in children with inflammatory bowel disease [IBD] is poorly investigated. We determined if IFX exposure correlates with long-term remission in children.

METHODS

In this retrospective study, all children with Crohn's disease [CD] and ulcerative colitis [UC], receiving maintenance IFX at our centre, were included. Serum trough levels and cumulative drug exposure were correlated with clinical, biological, and endoscopic remission. All children received proactive drug monitoring and dose adaptation aiming to target a therapeutic window of 3-7 µg/mL. All data are presented as median [interquartile range].

RESULTS

A total of 686 serum levels during IFX maintenance in 52 paediatric patients [33 CD and 19 UC] were included (median 9 [4-18] per patient). With a median of 17 [8-36] months under IFX therapy, 39/52 [75%] patients were in clinical remission and 29/40 [73%] patients were in endoscopic remission. Median IFX trough levels were significantly higher when children achieved clinical remission (5.4 [3.8-8.0] µg/mL versus 4.2 [2.6-6.7] µg/mL), biological remission (5.2 [3.7-7.7] µg/mL versus 4.2 [2.6-6.5] µg/mL), combined clinical and biological remission (5.7 [4.0-8.2] µg/mL versus 4.4 [2.7-6.8] µg/mL) and endoscopic remission (6.5 [4.2-9.5] µg/mL versus 3.2 [2.3-5.6] µg/mL) compared with not meeting these criteria [all p ≤ 0.001].

CONCLUSIONS

In this large paediatric cohort, children with clinical and/or endoscopic remission had significantly higher IFX exposure during maintenance therapy. We showed excellent outcome data using serial and systematic measurements of drug levels. This could provide a rationale for the use of proactive drug monitoring in children in order to improve long-term outcomes.

Association Between Infliximab Drug and Antibody Levels and Therapy Outcome in Pediatric Inflammatory Bowel Diseases

OBJECTIVES

While infliximab pharmacokinetics are associated with therapy outcome in adult inflammatory bowel disease (IBD) population, limited data are available in pediatric patients. We aimed to define the relationship between infliximab trough and antibodies' levels (IFX-TL, ATI) and clinical, biomarker remission.

METHODS

IFX-TL and ATI were routinely obtained between 2011 and 2017. Associations with clinical and inflammatory (C-reactive protein, CRP) end-points were studied throughout the first year of infliximab therapy.

RESULTS

A total of 63 patients (50 Crohn disease, 13 ulcerative colitis, median follow-up 16 months, median 8 samples/patient) were included, and 773 sera-samples were analyzed. Sera of patients in clinical remission had higher median IFX-TLs than sera of those with active disease (4 vs 2.25 μg/mL, P < 0.0001). In addition, patients with normal CRP had a higher median IFX-TL than those with elevated CRP (P = 0.02). Moreover, IFX-TL > 9.2 μg/mL at week 2 predicted clinical remission by week 14 (sensitivity 71.4%, specificity 81.2%, area under curve (AUC) = 0.73, P = 0.02) and IFX-TL > 2.2 μg/mL at week 6 predicted infliximab retention beyond 1 year of treatment (sensitivity 88.9%, specificity 100.0%, AUC = 0.974, P < 0.0001).

CONCLUSIONS

A significant association between IFX-TL and ATI and clinical and biomarker remission status in pediatric IBD patients was demonstrated, including a temporal association between week 2, 6 levels and outcome of induction and between week 6 and 14 levels and remission at 1 year of therapy. These findings suggest that therapeutic drug monitoring may be considered for management guidance among pediatric IBD patients.

Vedolizumab use after failure of TNF-α antagonists in children and adolescents with inflammatory bowel disease

BACKGROUND

Vedolizumab is safe and effective in adult patients with Crohn's disease (CD) and ulcerative colitis (UC); however, data in children with inflammatory bowel disease (IBD) are scarce. Therefore, we evaluated vedolizumab use in a cohort of Austrian paediatric patients with IBD.

METHODS

Twelve patients (7 female; 7 CD; 5 UC), aged 8-17 years (median, 15 years), with severe IBD who received vedolizumab after tumour necrosis factor α antagonist treatment were retrospectively analysed. Clinical activity scores, relevant laboratory parameters, and auxological measures were obtained at infusion visits.

RESULTS

In the CD group, 1/7 patient discontinued therapy due to a severe systemic allergic reaction; 1/7 and 2/7 patients achieved complete and partial response, respectively, at week 14; and 3/7 patients discontinued therapy due to a primary non-response or loss of response. In the UC group, complete clinical remission was achieved at weeks 2, 6, and 14 in 2/5, 1/5 and 1/5 patients respectively; partial response was observed in one patient at week 2. CD activity scores did not significantly change from baseline to week 38 (median 47.5 vs. 40 points, p = 1,0), while median UC activity scores changed from 70 to 5 points (p < 0,001). Substantial weight gain and increased albumin and haemoglobin levels were observed in both groups.

CONCLUSION

These results demonstrate that vedolizumab can be an effective treatment for individual paediatric patients with IBD who are unresponsive, intolerant, or experience a loss of efficacy in other therapies. However, vedolizumab appears to be more effective in paediatric UC than in paediatric CD.

Current Practices for Therapeutic Drug Monitoring of Biopharmaceuticals in Pediatrics

Biopharmaceuticals have recently emerged as effective treatments for refractory pediatric autoimmune conditions. Several reports have shown a relationship between drug concentration, antidrug antibodies, and clinical response in these patients, strongly suggesting the potential interest, usefulness, and reliability of therapeutic drug monitoring (TDM) in children. This article reviews the current state of research in juvenile idiopathic arthritis, pediatric inflammatory bowel disease, and pediatric psoriasis from a TDM point of view. There is a remarkable lack of evidence-based data in pediatric patients, which is reflected throughout the article. Most investigations of TDM are focused on research of tumor necrosis factor alpha antagonists in inflammatory bowel disease, albeit preliminary publications are emerging from pediatric rheumatologists and dermatologists. To date, immunogenicity has been a primary concern, particularly regarding infliximab and adalimumab therapy in children, as it may lead to a loss of therapeutic response. Preliminary investigations show that adjusting the dose according to blood drug concentrations improves disease outcomes by overcoming antidrug antibodies, suggesting a crucial role for TDM. Patients who receive other drugs, such as etanercept, abatacept, or tocilizumab, could benefit from TDM because dosage can be optimized by adjusting it to the minimum effective dose.

Therapeutic Drug Monitoring in Pediatric Inflammatory Bowel Disease

PURPOSE OF REVIEW

Therapeutic drug monitoring (TDM) has emerged as a useful tool to optimize the use of drug therapies in adults with inflammatory bowel disease (IBD), including both Crohn's disease (CD) and ulcerative colitis (UC), especially during the use of biological therapies, for which the pharmacokinetics and pharmacodynamics are highly variable among patients. Fewer data exist in children. This review examines the current literature on TDM in pediatric IBD.

RECENT FINDINGS

Drug clearance is affected by a number of patient and disease factors. For thiopurines, adjusting dosing by monitoring 6-thioguanine (6TGN) and 6-methylmercaptopurine ((6MMP) levels is demonstrated to maximize response and minimize toxicity, while monitoring metabolite levels when treating with anti-tumor necrosis factor (anti-TNF) remain controversial. While in adults the use of TDM in the setting of loss of response to anti-TNF therapy is established, in children, only a small number of studies exist, but these too have encouraging results. There are however, conflicting data regarding the optimal timing of TDM, comparing "reactive" monitoring and "proactive" monitoring. No such data exist in pediatrics. TDM is cost-effective, and dose reduction may represent a safety benefit. There are limited adult data for use of TDM for the newer biologics, vedolizumab and ustekinumab, but early results suggest similarly promising utility. The use of TDM in pediatric IBD is increasing in clinical practice, with similar efficacy to adults demonstrated in children with loss of response to anti-TNF therapy. More prospective studies are needed in children to examine proactive monitoring and utility of TDM with newer biologics.

Immunogenicity of biologics in inflammatory bowel disease

Crohn's disease and ulcerative colitis are chronic inflammatory disorders of the gastrointestinal tract. Treatment options include biologic therapies; however, a proportion of patients lose response to biologics, partly due to the formation of anti-drug antibodies (ADAbs). Concomitant immunosuppressive agents reduce the development of ADAbs. This review article aims to assess the immunogenicity of biologic therapies and their clinical implications. A comprehensive literature search was conducted for articles published January 2009 to August 2015 reporting immunogenicity to adalimumab (ADM), certolizumab pegol (CZP), golimumab, infliximab (IFX), ustekinumab, and vedolizumab in inflammatory bowel disease (IBD). Eligible articles were reviewed and quality assessed by independent reviewers. Overall, 122 publications reporting 114 studies were assessed. ADAbs were reported for all agents, but the percentage of patients developing ADAbs was extremely variable, with the highest (65.3%) being for IFX administration to patients with IBD. ADAb presence was frequently associated with a reduction in primary efficacy and a loss of response, and, for IFX, an increase in adverse events (AEs). Lower serum levels of ADM, CZP and IFX were seen in ADAbs-positive rather than ADAbs-negative patients; pharmacokinetic data were unavailable for other therapies. Little information was available regarding the timing of ADAb development; studies reported their detection from as early as 10-14 days up to months after treatment initiation. Biologic therapies carry an intrinsic risk of immunogenicity, although reported rates of ADAbs vary considerably. The clinical implications of immunogenicity are a concern for effective treatment; further research, particularly into the more recently approved biologics, is required.

Evaluation of Infliximab Therapy in Children with Crohn's Disease Using Trough Levels Predictors

BACKGROUND

In adults, infliximab (IFX) levels correlate with disease activity, and antibodies to IFX (ATIs) predict treatment failure. We aimed to determine the association of IFX levels and ATIs with disease activity in a paediatric population. We prospectively collected blood, stool, and clinical data from 65 patients (age 10.5-15.1 years) with Crohn's disease (CD) before IFX administration, and measured IFX trough levels, ATIs, and faecal calprotectin levels (CPT). Samples were collected during maintenance therapy. We used multivariate analysis to identify the predictors of IFX levels.

SUMMARY

Lower levels of IFX were associated with ATIs positivity (OR 0.027, 95% CI 0.009-0.077). Higher C-reactive protein (CRP) level, erythrocyte sedimentation rate, and CPT levels were found in patients with lower IFX levels. The optimal combination of sensitivity (0.5) and specificity (0.74) for disease activity was calculated for IFX levels ≥1.1 µg/mL using CRP level <5 mg/L as a marker of laboratory remission. In a model that used CPT ≤100 µg/g as the definition of remission, the optimal IFX trough level was 3.5 µg/mL. No independent association between remission and ATIs was found in our study population. However, we found an independentz association between IFX levels and serum albumin levels (OR 1.364, 95% CI 1.169-1.593), p < 0.001. Key Messages: The paediatric population was similar to adult populations in terms of the association between IFX and ATIs as well as between IFX and disease activity.

Immunogenicity of Biologics in Chronic Inflammatory Diseases: A Systematic Review

OBJECTIVES

A systematic review was conducted to explore the immunogenicity of biologic agents across inflammatory diseases and its potential impact on efficacy/safety.

METHODS

Literature searches were conducted through November 2016 to identify controlled and observational studies of biologics/biosimilars administered for treatment of rheumatoid arthritis (RA), psoriatic arthritis (PsA), juvenile idiopathic arthritis (JIA), ankylosing spondylitis (AS), non-radiographic axial spondyloarthritis (nr-axSpA), psoriasis (Ps), Crohn's disease, and ulcerative colitis.

RESULTS

Of >21,000 screened publications, 443 were included. Anti-drug antibody (ADAb) rates varied widely among biologics across diseases (and are not directly comparable because of immunoassay heterogeneity); the highest overall rates were reported with infliximab (0-83%), adalimumab (0-54%), and infliximab biosimilar CT-P13 (21-52%), and the lowest with secukinumab (0-1%), ustekinumab (1-11%), etanercept (0-13%), and golimumab (0-19%). Most ADAbs were neutralizing, except those to abatacept and etanercept. ADAb+ versus ADAb- patients had lower rates of clinical response to adalimumab (RA, PsA, JIA, AS, Ps), golimumab (RA), infliximab (RA, PsA, AS, Ps), rituximab (RA), ustekinumab (Ps), and CT-P13 (RA, AS). Higher rates of infusion-related reactions were reported in infliximab- and CT-P13-treated ADAb+ patients. Background immunosuppressives/anti-proliferatives reduced biologic immunogenicity across diseases.

CONCLUSIONS

Based on reviewed reports, biologic/biosimilar immunogenicity differs among agents, with the highest rates observed with infliximab and adalimumab. As ADAb formation in biologic-/biosimilar-treated patients may increase the risk of lost response, the immunogenicity of these agents is an important (albeit not the only) consideration in the treatment decision-making process.

Infliximab Optimization Based on Therapeutic Drug Monitoring in Pediatric Inflammatory Bowel Disease

BACKGROUND

Infliximab (IFX) is an effective treatment for the management of moderate to severe inflammatory bowel disease (IBD). Low-serum IFX levels are associated with the development of antibodies to IFX (ATI), which subsequently associated with clinical relapse and increased morbidity. The primary purpose of this study is to examine the relation between dose and interval to IFX level. Secondary goal is to evaluate the relation between IFX level and ATI in a pediatric IBD population.

METHODS

We performed a retrospective chart review of all children diagnosed with IBD and treated with IFX at a tertiary care pediatric IBD center. We performed our analysis based on prescribed dosing intervals and rounded dose up to 5 or 10 mg/kg as indicated in clinical practice.

RESULTS

Our study included 278 samples from 129 children on IFX. ATI were detected in 37 samples (13.3%). Low IFX levels (<3 μg/mL) were detected in 37.2% of children receiving IFX. Samples with ATI present had significantly lower levels of IFX than samples in which ATI were not present. For the dose 5 mg/kg, Q6 dosing had significantly higher IFX levels than Q8 dosing (P = 0.009). Higher IFX levels were seen with interval shortening rather than dose escalation.

CONCLUSIONS

We demonstrate that low IFX levels are associated with development of immunogenicity to IFX as measured by ATI. We demonstrate that interval shortening rather than dose escalation results in higher IFX levels. We suggest that given the high number of IFX levels below 3 μg/mL in patients, early IFX level evaluation or primary initiation of Q6 week dosing be considered.

Serum-Infliximab Trough Levels in 45 Children with Inflammatory Bowel Disease on Maintenance Treatment

The role of trough serum infliximab (s-IFX) and antibodies toward IFX (ATI) during maintenance treatment remains unclear in children. The aim of the present study was to investigate trough s-IFX and ATI to identify any correlation with inflammatory activity and clinical response in a pediatric inflammatory bowel disease (IBD) cohort. We investigated the s-IFX trough levels in pediatric IBD patients (n = 45) on maintenance IFX treatment. Ninety-three blood samples were collected and demographics, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and albumin were recorded. The mean s-IFX trough level was 5.2 µg/mL. The mean trough s-IFX level was significantly higher in the samples taken during remission (7.2 µg/mL) compared to active disease (4.5 µg/mL, p < 0.05). The trough s-IFX levels correlated with ESR, CRP, and albumin. S-IFX was undetectable in eight of the patients, all with positive ATI and active disease. Surprisingly, clinical and biochemical remission was observed at only 26 of the 93 visits. The correlation between dose variations and changes in trough s-IFX was not evident. In line with studies in adults, the s-IFX trough levels correlated with response to infliximab.

Clinical Use of Infliximab Trough Levels and Antibodies to Infliximab in Pediatric Patients With Inflammatory Bowel Disease

OBJECTIVES

Optimizing infliximab (IFX) treatment in pediatric patients with inflammatory bowel disease (IBD) by using serum infliximab (S-IFX) trough levels and antibodies to IFX is recommended. There is need for studies assessing this strategy in clinical practice.

METHODS

We retrospectively identified all pediatric patients with IBD (n = 146, median age 14.8 years) treated with IFX at our tertiary referral center from 2003 to 2014. All were analyzed for IFX trough levels (S-IFX, n = 475), and IFX antibody (IFX-Ab, n = 219) titers were included. Both were analyzed using enzyme-linked immunosorbent assay. We correlated these parameters with concurrently analyzed fecal calprotectin levels and the treatment outcome.

RESULTS

If IFX had no efficacy, or a loss of response occurred, 40 of 64 (63%) had trough levels <2.0 mg/L, with negative IFX-Ab in 37 of 59 (63%). If the S-IFX was very low (<0.2 mg/L), 4 of 36 still had negative IFX-Ab. Concurrent azathioprine therapy did not relate to IFX-Ab. Fecal calprotectin was significantly lower in patients with clinical remission or ongoing therapy compared with those with subsequent loss of efficacy: medians 95 μg/g (33-308) and 670 μg/g (264-1473), P < 0.0001. The S-IFX median was substantially higher in patients with either remission or ongoing therapy, compared with those with no or loss of efficacy: 3.7 mg/L (1.8-5.4) and 1.2 mg/L (0.03-4.4, P = 0.01), respectively.

CONCLUSIONS

Measuring IFX trough levels and fecal calprotectin has a potential impact on the treatment strategies and should be included in clinical routine. Low IFX trough levels associate with increased antibodies to IFX in most, but not in all cases.

Comparison of Fecal Calprotectin Methods for Predicting Relapse of Pediatric Inflammatory Bowel Disease

Background. Pediatric inflammatory bowel disease (IBD) is on the rise worldwide. Endoscopies are necessary for IBD assessment but are invasive, expensive, and inconvenient. Recently, fecal calprotectin (FCal) was proposed as a noninvasive and specific marker of gut inflammation. We evaluated the analytical performance of three FCal assays and their clinical performance in predicting relapse in pediatric IBD. Methods. This study used 40 pediatric IBD and 40 random non-IBD patients' fecal samples. Two automated ELISAs (Bühlmann and PhiCal® Calprotectin-EIA) and an EliA (Phadia 250 EliA-Calprotectin) were used to evaluate the analytical performance. The clinical performance was assessed by PhiCal Calprotectin-EIA, EliA-Calprotectin, and Bühlmann immunochromatographic point-of-care test (POCT). Results. All assays displayed acceptable analytical performance below and above the medical decision cut-off [imprecision (CV < 10% intra-assay; <15% interassay); linearity (overall mean % deviation < 16.5%)]. The agreement with PhiCal Calprotectin-EIA was 100% and 78.6% for Bühlmann (95% CI, 87.5-100; Kappa: 1) and EliA-Calprotectin (95% CI, 60.5-89.8; Kappa: 0.32), respectively, and 63.6% between Bühlmann and EliA-Calprotectin (95% CI, 46.6-77.8; Kappa: 0.16). All assays evaluated had similar clinical performance [AUC: 0.84 (EliA-Calprotectin); 0.83 (POCT and PhiCal Calprotectin-EIA)]. Conclusion. FCal levels determined using the same method and assay together with clinical history would be a noninvasive and useful tool in monitoring pediatric IBD.

Golimumab Therapy in Six Patients With Severe Pediatric Onset Crohn Disease

Anti-tumor necrosis factor-alpha (TNF-α) blockade is so far the most effective therapy for extensive pediatric Crohn disease (CD), but loss of response is frequently encountered. We describe here the use of golimumab (Simponi) in 6 pediatric CD patients with antibody formation/loss of response to infliximab and adalimumab. Most patients had undergone surgery but had poor disease control. After introduction of golimumab, the levels of inflammatory markers and fecal calprotectin declined at first, but the response was not sustained. Each patient needed dose escalation of golimumab from 4 to 2 week intervals, to maintain response and to increase trough levels. Importantly, most patients were able to attend school when undergoing golimumab therapy. As with other anti-TNFα drugs, follow-up of drug levels is advisable. Although golimumab therapy failed in most patients, it is an alternate treatment option in pediatric patients with severe CD. The therapeutic response, however, is suboptimal in anti-TNFα exposed patients.

Progress in the treatment and outcome of pediatric inflammatory bowel disease patients

INTRODUCTION

The number of pediatric patients with inflammatory bowel disease (IBD), namely Crohn´s disease, ulcerative colitis and unclassified colitis, has rapidly increased in Western countries. Areas covered: This review discusses how the treatment of pediatric IBD patients has improved,with attention given to therapeutic quality and cost. The literature search covers Medline-PubMed and the Cochrane Library, with February 2016 as the last search dates. Similarly to what has been the trend in the management of adult IBD, pediatric IBD therapy has become more active than before. High use of immunosuppressants and the availability of biological therapeutic agents has helped to control the extensive and aggressive course of pediatric IBD. Full disease control at an early phase has advantages such as preserving normal child growth and development, maintaining overall good health and quality of life, as well as decreasing the psychosocial burden of the disease. Expert commentary: A key research direction is to tailor treatment modalities according to anticipated individual phenotype and disease course. Another is to reduce healthcare costs by decreasing the so-far high rate of surgery of pediatric IBD patients, and, instead, to develop a more active approach to treatment than before.

Practical Use of Infliximab Concentration Monitoring in Pediatric Crohn Disease

OBJECTIVES

Therapeutic drug monitoring (TDM) that guides infliximab (IFX) intensification strategies has been shown to improve IFX efficacy. We conducted a review to evaluate the utility of TDM in the assessment and subsequent management of IFX loss of response in our pediatric population with Crohn disease (CD).

METHODS

Single-center retrospective study of patients with CD receiving IFX that had TDM from December 2009 to September 2013. We defined subtherapeutic trough as a drug level below the detection limit of the Prometheus enzyme-linked immunoabsorbant assay and Anser reference values (1.4 and 1 μg/mL, respectively) or a mid-interval level <12 μg/mL.

RESULTS

One hundred ninety-one IFX concentration tests were performed on 72 patients with CD with loss of response to therapy as the primary indication (72%). 34% of all TDM were subtherapeutic. After initial TDM, 25 of the 72 patients received regimen intensification with 72% in clinical remission at 6 months. Including all of the TDM that resulted in IFX dose intensification, we found a significant improvement in 6-month remission rates whether intensification followed mid-interval (88% remission) or trough (56% remission) testing (P = 0.026). Antibody to infliximab was found in 14 patients with 5 occurring in the first year of therapy. Furthermore, 71% of patients with antibody to infliximab that were switched to an alternative anti-tumor necrosis factor achieved clinical remission at six months. In multivariable regression analysis, we found IFX dose (mg/kg), IFX dosing frequency (weeks), and the erythrocyte sedimentation rate at the previous infusion were significantly associated with the IFX concentration.

CONCLUSIONS

TDM in our pediatric population with CD led to informed clinical decisions and improved rates of clinical remission.

The association of infliximab trough levels with disease activity in pediatric inflammatory bowel disease

OBJECTIVE

Low serum trough levels (TLs) of infliximab (IFX) and antibodies to IFX (ATIs) are associated with the loss of therapeutic response in adults with inflammatory bowel disease (IBD) receiving IFX. Until now, pediatric data are scarce. Therefore, we aimed to cross-sectionally investigate the association between ATIs and IFX TLs, and clinical and biochemical disease activity in children receiving IFX for IBD.

MATERIAL AND METHODS

Children aged <18 years receiving IFX maintenance treatment for Crohn's disease (CD) or ulcerative colitis (UC) at three Dutch hospitals were included. Prior to two consecutive IFX infusions, IFX TLs and ATI levels were measured. Clinical disease activity was determined by Pediatric Crohn's Disease Activity Index (PCDAI) and Pediatric Ulcerative Colitis Activity Index (PUCAI), for CD and UC, respectively. Biochemical disease activity was assessed by serum C-reactive protein (CRP) and fecal calprotectin (FC). Clinical remission was defined as a PUCAI or PCDAI score of <10. Therapeutic range of IFX was considered 3-7 µg/ml.

RESULTS

Thirty-nine patients were included (31 CD; 16 females). Median age was 15 years. Median IFX TL was 3.5 µg/ml [IQR 2-7]. Subtherapeutic and supratherapeutic TLs were found in 38% and 23% of children, respectively. ATIs were detected in four patients. A correlation was found between IFX TL and CRP [rs = -0.51; p < 0.01] and FC [rs = -0.49; p < 0.01]. However, when only clinical disease activity was considered, no difference in median TL was found between remission and active disease (resp. 3.5 µg/ml [IQR 2-5] and 2.3 µg/ml [IQR 0.3-4.6]; p = 0.2).

CONCLUSIONS

IFX TLs are related to biochemical markers of disease activity. This could provide a rationale for monitoring TLs in children receiving IFX for IBD.

The Role of Therapeutic Drug Monitoring of Anti-Tumor Necrosis Factor Alpha Agents in Children and Adolescents with Inflammatory Bowel Disease

BACKGROUND

Anti-tumor necrosis factor alpha (TNFα) therapy is effective in pediatric patients with inflammatory bowel disease (IBD) but associated with a risk of developing anti-drug antibodies (ADA) which lower the efficacy. Incorporating measurement of trough levels and ADA (therapeutic drug monitoring) may prevent the development of neutralizing ADA or could contribute to more optimal treatment strategies if ADA are already formed. The aim of this review was to investigate the role of therapeutic drug monitoring in children and adolescents with IBD exposed to anti-TNFα agents.

METHODS

A literature search identified publications that measured anti-TNFα drug trough levels and/or ADA in children or adolescents with IBD. Studies were eligible when (1) article was written in English, (2) original data were available, (3) full text article or abstract was available, (4) measurement of antibodies against anti-TNFα drugs or trough level of anti-TNFα drugs were reported, and (5) levels were measured in pediatric patients with IBD.

RESULTS

The search yielded 811 articles, of which 795 articles were excluded based on title or abstract. A total of 14 studies were included in the review.

CONCLUSIONS

Therapeutic drug monitoring within the pediatric IBD population certainly has a potential benefit. As occurrence of immune reactions to anti-TNFα agents varies widely, incorporating measurement of IFX trough levels at week 8 or week 14 predicts therapy response and allows for dose adjustments to reach therapeutic drug concentrations. However, a clinically relevant cutoff level for ADA has not been defined yet, and the optimal intervention strategy still has to be determined.

Treatment of complex perianal fistulas with seton and infliximab in adolescents with Crohn's disease

BACKGROUND AND AIMS

Treatment of complex perianal fistulas associated with Crohn's disease is challenging. In adults, seton drainage combined with infliximab therapy has proven to be more effective than either one alone. Results following such treatment among pediatric patients have not been reported previously. The aim of this study was to describe outcomes after combined seton and infliximab treatment for complex perianal fistulas in adolescents with Crohn's disease.

METHODS

We performed a retrospective medical record review of all consecutive Crohn's disease patients treated for perianal fistulas with seton drainage and infliximab between 2007 and 2013 (n=13). A follow-up interview was conducted at median of two years.

RESULTS

Median age at fistula diagnosis was 14years. Following seton placement in fistula tracks, infliximab induction was administered at weeks 0, 2, and 6 and maintenance therapy at 8-week intervals. Over 90% responded to seton drainage and infliximab induction. Final fistula response was obtained at median of 8weeks, being complete in 77% and partial in 15%. Setons were kept in place for median of 8months. Fistulas recurred in 23% over a year after the final response. At last follow-up, 85% still had a response and 70% were free from perianal symptoms. Most were still on anti-TNF-α therapy, but one third had switched to adalimumab. Patients' anorectal function was well preserved and overall satisfaction with the treatment was high.

CONCLUSIONS

The results suggest that combining seton drainage with infliximab therapy improves the perianal fistula response rates in pediatric patients.

Skin reactions during anti-TNFα therapy for pediatric inflammatory bowel disease: a 2-year prospective study

BACKGROUND

Although the development of therapy-related skin reactions is common along with an increase in the number of adult patients receiving anti-TNFα, there are few studies on pediatric inflammatory bowel disease; hence, this prospective study focuses on skin reactions related to infliximab therapy.

METHODS

All pediatric patients with inflammatory bowel disease undergoing infliximab therapy were prospectively screened for the presence of skin manifestations at the time of each infusion between March 1, 2011 and March 31, 2011 at Children's Hospital, Helsinki, Finland. Blood inflammatory markers and fecal calprotectin levels were measured at the time of infusions.

RESULTS

During the study period, 84 children with inflammatory bowel disease (Crohn's n = 64) received infliximab infusions (the median duration of therapy 12.2 mo). Almost every other patient (n = 40; 47.6%) presented chronic skin reactions, 23% with lesions considered severe. Most commonly, the patient's ear lobes and scalp were affected with psoriasis-like manifestations, followed by their eyelids, perioral and pubic area, trunk, and the extremities. However, an HLA-Cw*0602 genotype associating with psoriasis was rare. Interestingly, most patients with skin reactions had a low degree of intestinal inflammation based on their fecal calprotectin levels (median level, 133 μg/g versus 589 in unaffected patients; P < 0.016). Seven patients (8.3% of all patients but 17% of those with skin lesions) discontinued the given therapy due to a skin reaction.

CONCLUSIONS

Skin reactions are common during maintenance therapy with infliximab in pediatric patients. For most patients, skin reactions seem to correlate with a low level of intestinal inflammation. Although potentially harsh, skin lesions mostly allow continuation of infliximab.

Biologic therapies in inflammatory bowel disease

Inflammatory bowel disease, including its 2 entities ulcerative colitis and Crohn's disease, is a chronic medical condition characterized by the destructive inflammation of the intestinal tract. Biologics represent a class of therapeutics with immune intervention potential. These agents block the proinflammatory cascade that triggers the activation and proliferation of T lymphocytes at the level of the intestine, therefore reestablishing the balance between the pro- and anti-inflammatory messages. All 7 biologics showing clinical benefits in inflammatory bowel disease are monoclonal antibodies. The following systematic review discusses the pharmacokinetics and efficacy of the tumor necrosis factor blockers infliximab, adalimumab, certolizumab pegol, and golimumab. In addition, we describe the α4 integrin inhibitors natalizumab and vedolizumab, which are directed against cell adhesion molecules, as well as the interleukin 12/23 blocker ustekinumab.

The long-term outcome of anti-tumor necrosis factor-α therapy related to fecal calprotectin values during induction therapy in pediatric inflammatory bowel disease

OBJECTIVE

Monitoring fecal calprotectin (FC) could assist in the assessment of the therapeutic response of inflammatory bowel disease (IBD). There are few studies on long-term prognosis related to the FC value response to infliximab induction therapy, thus providing the aim of this study on pediatric patients.

METHODS

FC levels were measured during the induction and maintenance phase of infliximab therapy (5 mg/kg) in 76 pediatric IBD patients introduced to maintenance therapy. The long-term outcomes and clinical disease activity were retrospectively related to the FC response to induction.

RESULTS

The median pretreatment FC level of 817 μg/g stool (range <5-24,000) declined to 372 μg/g (range 5-2430) by week 6, with a low level (<100 μg/g) in 35% (pooled comparable data for ulcerative colitis and Crohn's). Clinical activity indices showed remission in 59% (pediatric Crohn's disease activity index: <10, n = 33; pediatric ulcerative colitis activity index: <10 n = 12). In 49 patients (64%), infliximab therapy was discontinued (inadequate effect/surgery = 27; remission/bridging to azathioprine = 12; adverse effect = 6; antibodies to infliximab n = 4) during the study period with a median follow up of 1.1 years (interquartile range [IQR]: 0.71-4.4). Those who discontinued the therapy within the first year due to an inadequate effect had higher median FC level during induction than the other patients (median 633 µg/g, IQR: 197-819 and median 219 µg/g, IQR: 71-508, respectively; p < 0.025) and were less frequently in clinical remission at week 6 (p < 0.01).

CONCLUSIONS

The long-term prognosis of infliximab therapy is related to the response to induction therapy in pediatric IBD and reflected in low FC values between weeks 2 and 6 and clinical remission.

Outcomes following infliximab therapy for pediatric patients hospitalized with refractory colitis-predominant IBD

OBJECTIVES

Although randomized trials demonstrated the efficacy of infliximab for both pediatric Crohn disease and ulcerative colitis (UC), few patients in these studies exhibited colitis requiring hospitalization. The aims of this study were to determine the rate of subsequent infliximab failure and dose escalation in pediatric patients who started taking infliximab during hospitalization for colitis-predominant IBD, and to identify potential predictors of these endpoints.

METHODS

This is a single-center retrospective cohort study of patients admitted from 2005 to 2010 with Crohn colitis, UC, or IBD-unspecified (IBD-U) and initiated on infliximab.

RESULTS

We identified 29 patients (12 Crohn colitis, 15 UC, and 2 IBD-U; median age 14 years) with a median follow-up of 923 days. Eighteen patients (62%) required infliximab dose escalation (increased dose or decreased infusion interval). Infliximab failure occurred in 18 patients (62%) because of ineffectiveness in 12 (67%) and adverse reactions in 6 (33%). Twelve patients (41%) underwent colectomy. Subsequent need for infliximab dose escalation was associated with lower body mass index z score (P = 0.01), lower serum albumin (P = 0.03), and higher erythrocyte sedimentation rate (ESR) (P = 0.002) at baseline. ESR predicted subsequent infliximab dose escalation with an area under the curve of 0.89 (95% confidence interval [CI] 0.72-1.00) and a sensitivity and specificity at a cutoff of 38 mm/hour of 0.79 (95% CI 0.49-0.95) and 0.88 (95% CI 0.47-0.99), respectively.

CONCLUSIONS

Most hospitalized pediatric patients with colitis treated with infliximab require early-dose escalation and fail the drug long term. Low body mass index and albumin and high ESR, may identify patients who would benefit from a higher infliximab starting dose.

Review article: immunogenicity of anti-TNF biologics in IBD - the role of patient, product and prescriber factors

BACKGROUND

Anti-drug antibodies (ADAs) to biologic therapies contribute to the loss of response and infusion reactions to anti-TNF drugs in patients with inflammatory bowel disease (IBD). The reasons behind this immunogenicity are complex, and have not been the focus of a dedicated review for prescribers.

AIM

To provide an overview of the patient, product and prescriber factors, which have been associated with the immunogenicity of anti-TNF therapy, and draw conclusions for clinical practice.

METHODS

Review of representative observational studies and clinical trials from the IBD and other literature, which report associations with ADA development, with a focus on infliximab and adalimumab.

RESULTS

ADAs develop in 10-20% of patients receiving anti-TNF maintenance therapy, and these patients are three times more likely to lose response as ADA-negative patients. Patient genotype plays a role in ADA risk in a minority of patients, but age or disease type is not a major factor. Drug mishandling, such as agitation or freeze-thaw cycles, can induce protein aggregates, which are known to be immunogenic. Prescription of maintenance therapy with concomitant immunomodulators, and achieving suitable trough drug levels, reduces the risk of ADAs in patients with IBD.

CONCLUSIONS

Patients and prescribers can take several steps to reduce the risk of development of anti-drug antibodies to anti-TNF antibodies. Further research is required to determine if immunogenic factors identified in other situations apply to use of anti-TNFs in IBD.