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

Comparison of three immunoassays for infliximab trough level monitoring in paediatric inflammatory bowel diseases

Many clinical studies in paediatric inflammatory bowel diseases (IBD) use infliximab trough level (IFX-TL) and detection of antibody against infliximab (ATI). Hence, comparison of commercially available assays is needed in paediatric samples to assess their reliability and their comparability. We measured IFX-TL and ATI-TL in sera samples of 53 IBD children using three ELISA kits: Lisa-Tracker® Duo Infliximab (Theradiag®), Ridascreen® IFX monitoring (R-Biopharm®) and Promonitor® IFX (Grifols®). Regarding IFX-TL, median values were comparable (p > 0.05), a good statistical correlation has been observed (0.73 ≤ R² ≤ 0.85) between tested assays and the Bland-Altman analysis found an excellent agreement with a bias estimated between -0.56 and 0.12 and few values outside the 95% limits of agreement. However, qualitative comparison with therapeutic interval classifications showed some discrepancies (30.2%), mainly due to values near thresholds and more often than not with Theradiag® (22.6%). For ATI, because of non-standardized units, the qualitative comparison found a sensibly good agreement (98.1%). These data show a good agreement of IFX-TL and ATI measurement between three marketed ELISA assays with a small bias obtained. Variations in some results can lead to divergent therapeutic interval classifications and prompt us to be cautious in the interpretation of values near therapeutic thresholds.

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.

A Review on the Use of Anti-TNF in Children and Adolescents with Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) presents with disabling symptoms and may lead to insufficient growth and late pubertal development in cases of disease onset during childhood or adolescence. During the last decade, the role of anti-tumor necrosis factor (TNF) in the treatment of paediatric-onset IBD has gained more ground. The number of biologicals presently available for children and adolescents with IBD has increased, biosimilars have become available, and practices in adult gastroenterology with regards to anti-TNF have changed. The aim of this study is to review the current evidence on the indications, judicious use, effectiveness and safety of anti-TNF agents in paediatric IBD. A PubMed literature search was performed and included articles published after 2000 using the following terms: child or paediatric, Crohn, ulcerative colitis, inflammatory bowel disease, anti-TNF, TNF alpha inhibitor, infliximab, adalimumab, golimumab and biological. Anti-TNF agents, specifically infliximab and adalimumab, have proven to be effective in moderate and severe paediatric IBD. Therapeutic drug monitoring increases therapy effectiveness and safety. Clinical predictors for anti-TNF response are currently of limited value because of the variation in outcome definitions and follow-ups. Future research should comprise large cohorts and clinical trials comparing groups according to their risk profile in order to provide personalized therapeutic strategies.

Infliximab Trough Levels Are Associated With Mucosal Healing During Maintenance Treatment With Infliximab in Paediatric Crohn's Disease

BACKGROUND AND AIMS

Mucosal healing is an important treatment goal in Crohn's disease. We investigated the association between serum infliximab trough levels and mucosal healing, and the infliximab cut-off levels required for mucosal healing in paediatric patients.

METHODS

In this multicentre, retrospective, cross-sectional study, medical records and electronic data of paediatric patients with luminal Crohn's disease, who had received infliximab for ≥1 year, were examined. Ileocolonoscopy was performed on the same day as the infliximab infusion, and serum samples for trough levels were collected immediately before infusion. Mucosal healing was defined as a Simple Endoscopic Score for Crohn's Disease of 0. Univariate, multivariate logistic regression, and receiver operating characteristic curve analyses were performed.

RESULTS

Overall, 105 patients [median age 14.8 years] were included, with mucosal healing observed in 48.6%. Median serum infliximab trough levels were higher in patients with mucosal healing [4.5 µg/mL] than without [3.3 µg/mL, p = 0.002]. In the final multivariate model, infliximab trough level ≥4.2 µg/mL [p = 0.002] and ≥1-year duration from diagnosis to infliximab treatment [p = 0.003] were positively and negatively associated with mucosal healing, respectively. The infliximab trough level for achieving mucosal healing with a specificity of 80% was ≥5 µg/mL.

CONCLUSIONS

Associations between serum infliximab trough concentrations and mucosal healing were observed in paediatric patients. Identification of the infliximab trough level that positively associates with mucosal healing in most paediatric patients with Crohn's disease [≥5 µg/mL] may guide treatment decisions to optimise therapeutic response in the era of treat-to-target.

Causes of Treatment Failure in Children With Inflammatory Bowel Disease Treated With Infliximab: A Pharmacokinetic Study

OBJECTIVES

Anti-tumor necrosis factor antibodies have led to a revolution in the treatment of inflammatory bowel diseases (IBD); however, a sizable proportion of patients does not respond to therapy. There is increasing evidence suggesting that treatment failure may be classified as mechanistic (pharmacodynamic), pharmacokinetic, or immune-mediated. Data regarding the contribution of these factors in children with IBD treated with infliximab (IFX) are still incomplete. The aim was to assess the causes of treatment failure in a prospective cohort of pediatric patients treated with IFX.

METHODS

This observational study considered 49 pediatric (median age 14.4) IBD patients (34 Crohn disease, 15 ulcerative colitis) treated with IFX. Serum samples were collected at 6, 14, 22 and 54 weeks, before IFX infusions. IFX and anti-infliximab antibodies (AIA) were measured using enzyme linked immunosorbent assays. Disease activity was determined by Pediatric Crohn's Disease Activity Index or Pediatric Ulcerative Colitis Activity Index.

RESULTS

Clinical remission, defined as a clinical score <10, was obtained by 76.3% of patients at week 14 and by 73.9% at week 54. Median trough IFX concentration was higher at all time points in patients achieving sustained clinical remission. IFX levels during maintenance correlated also with C-reactive protein, albumin, and fecal calprotectin. After multivariate analysis, IFX concentration at week 14 >3.11 μg/mL emerged as the strongest predictor of sustained clinical remission. AIA concentrations were correlated inversely with IFX concentrations and directly with adverse reactions.

CONCLUSIONS

Most cases of therapeutic failure were associated with low serum drug levels. IFX trough levels at the end of induction are associated with sustained long-term response.

Higher Postinduction Infliximab Serum Trough Levels Are Associated With Healing of Fistulizing Perianal Crohn's Disease in Children

BACKGROUND

There is some evidence in adults that higher serum infliximab (IFX) levels are needed to adequately treat fistulizing perianal Crohn's disease (CD). However, data in children are lacking. We aimed to determine postinduction serum trough IFX levels that are associated with healing of fistulizing perianal CD (PCD) at week 24.

METHODS

In a multicenter inception cohort study, consecutive children younger than age 17 years with fistulizing perianal CD treated with IFX between April 2014 and June 2017 who had serum trough IFX titers measured before the fourth infusion were included. Area under the receiver operating characteristic curve (AUROC) was calculated to determine the best cutoff to predict fistula healing.

RESULTS

A total of 667 children with Crohn's disease were recruited, with 85 (12.7%) patients diagnosed with fistulizing PCD. There were 27 of 52 (52%) children in whom pre-fourth infusion IFX levels were measured (mean age, 12.57 ± 5.12 years). At week 24, 14 of 27 (52%) patients responded with healing/healed PCD, whereas the rest had ongoing active fistulizing disease. The median IFX pre-fourth dose level in the responders was 12.7 ug/mL, compared with 5.4 ug/mL in the active disease group (P = 0.02). There was a strong correlation between IFX levels and healing of fistulizing PCD at week 24 (r = 0.65; P < 0.001). The AUROC was 0.80 (95% confidence interval, 0.64-0.97; P = 0.007) for pre-fourth IFX level to predict response of fistulizing PCD at week 24, and a level of 12.7 ug/mL best predicted fistula healing.

CONCLUSIONS

Higher trough IFX levels are associated with healing of fistulizing perianal CD.

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.

Therapeutic drug monitoring was helpful in guiding the decision-making process for children receiving infliximab for inflammatory bowel disease

AIM

This study examined the impact of therapeutic drug monitoring (TDM) on clinical decision-making for children receiving infliximab for inflammatory bowel disease (IBD).

METHODS

The medical records of children with IBD who had infliximab trough levels (ITLs) measured between January 2013 and December 2015 at two Canadian tertiary-care centres were examined. The indications for TDM, clinical and laboratory disease activity indices and TDM-driven treatment changes to infliximab therapy were documented.

RESULTS

We included 107 consecutive serum measurements of ITLs in 73 children (40 boys), with a median age of 16.1 years, including 52 with Crohn's disease. TDM was performed due to concerns about clinical disease activity in 24/107 (22.4%) measurements and 83 (77.6%) were ordered as routine tests. Of these, 38 (35.5%) ITLs were suboptimal (<3.5 μg/mL) and 36 (34.0%) resulted in more frequent doses of infliximab, with subsequent improvements in disease biomarkers. Interval changes were implemented as a result of 34 (32.0%) ITLs, with shorter intervals in 19 (17.0%) cases, and seven (6.5%) ITLs resulted in adding or increasing doses of immunomodulators. In addition, four children were switched to adalimumab.

CONCLUSION

Therapeutic drug monitoring was helpful in guiding the decision-making process for children with IBD on infliximab.

Biological Therapy in Pediatric Inflammatory Bowel Disease: A Systematic Review

The incidence of inflammatory bowel disease (IBD) has increased steadily worldwide, both in adult and in children; approximately 25% of IBD patients are diagnosed before the age of 18. The natural history of IBD is usually more severe in children than in adults, and can be associated with linear growth impairment, delayed puberty onset, reduced bone mass index, malnutrition, and the need for surgery. Biological therapies, especially blocking tumor necrosis factor-α (TNFα), have radically modified the treatment strategies and disease course of IBD in children. In particular, drugs such as Infliximab and Adalimumab are routinely used in the treatment of pediatric IBD. The role of Infliximab and Adalimumab in the management of pediatric IBD has been recently updated in the Consensus guidelines of ECCO/ESPGHAN. Data regarding short-term and long-term efficacy and safety of these drugs in children, and the effects of "top-down" and "step-up" strategies, are lacking. In this paper, the authors will review current indications, efficacy, and safety of biological therapy in pediatric IBD patients, evaluating all articles published after ECCO/ESPGHAN guidelines publication. The authors carried out a systematic search through MEDLINE through PubMed (http://www.ncbi.nlm.nih.gov/pubmed/) Embase, CINAHL, Cochrane Library, and gray literature, from January 2013 to January 2016. Anti-TNFα has been shown to be effective and safe to maintain remission and to achieve mucosal healing. Multicenter trials based on large sample size cohorts are needed to better clarify long-term efficacy of anti-TNFα and the real incidence of treatment-related complications in pediatric IBD.

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.

Improving pediatric Inflammatory Bowel Disease (IBD) follow-up

Standardization of Inflammatory Bowel Disease (IBD) care through participation in the ImproveCareNow (ICN) Network has improved outcomes for pediatric patients with IBD, but under the current care model, our improvements have plateaued. Current ICN model care guidelines recommend health supervision visits every six months. We identified a gap in our practice's ability to ensure either a routine six month follow-up or a rapid follow-up after a disease flare, and a significant number of patients with active disease status during a six month period lacked timely reassessment after interventions or medication changes. Telemedicine provides an alternative method of care delivery to address these gaps, but has had limited use in patients with IBD. A multi-step approach to offer alternative follow-up care options via telemedicine was developed with potential impact on remission rates and quality of life. Short term goals of the pilot were to improve telemedicine access for patients with IBD were to 1) increase the percent of patients with active disease with a follow-up completed within two months of a visit from 40% to 70%, 2) increase the percent of patients with a visit scheduled within two months of their last sick visit from 20% to 70% (interim measure), 3) increase the number of eVisits from zero visits per month to two visits per month during pilot phase, 4) increase electronic communication with patients from zero messages per month to 200 messages per month, 5) no change in complications or adverse events (defined as an unplanned visit or ED (emergency department) encounter within 30 days of an eVisit. The expected outcomes of the e-visit model were to: maintain baseline care standards and health screening capabilities, improve access to care, and provide equivalent care delivery (no increase in the number of unplanned clinical encounters). Using the IHI model for improvement (Plan-Do-Study-Act) we have seen a progressive increase in the rate of patient signups for the electronic medical record patient portal, with a baseline median of 20% per clinic compared with a current median of approximately 70% after six months. We successfully implemented e-messaging in its pilot form among five providers and have seen steady uptake in patient use from 5 patient initiated messages during the first month to 76 messages/month over the past three months. E-visits have replaced a total of 32 visits to date. Medications, nutrition, and disease activity were appropriately screened and managed electronically without the need for a physical office visit by the treating gastroenterologist. Access to care was improved in that all patients completed their e-visits from their homes without missing school or work and did not require a physical office visit. One visit successfully identified worsening of the patient's clinical course and resulted in a scheduled office visit request, but no unplanned office visits or ED visits have occurred. This report represents the first description of telemedicine use in routine clinical care in children with IBD. We anticipate continuing use of this novel mode of health care delivery in pediatrics in an effort to increase the proportion of patients seen for interval follow-up, after IBD diagnosis, or mild flare in an effort to target early treatment changes that should result in improved remission and patient reported outcomes. E-visits are less expensive and time consuming than traditional visits and may serve as an additional method of cost savings by matching care to a patient's individual needs.