Association of trough serum infliximab to clinical outcome after scheduled maintenance treatment for Crohn's disease

Clinical effectiveness and cost-effectiveness of use of therapeutic monitoring of tumour necrosis factor alpha (TNF-α) inhibitors [LISA-TRACKER® enzyme-linked immunosorbent assay (ELISA) kits, TNF-α-Blocker ELISA kits and Promonitor® ELISA kits] versus standard care in patients with Crohn's disease: systematic reviews and economic modelling

BACKGROUND AND OBJECTIVES

Systematic reviews and economic modelling of clinical effectiveness and cost-effectiveness of therapeutic monitoring of tumour necrosis factor alpha (TNF-α) inhibitors [using LISA-TRACKER^® enzyme-linked immunosorbent assay (ELISA) kits (Theradiag, Marne La Vallee, France, or Alpha Laboratories, Heriot, UK), TNF-α-Blocker ELISA kits (Immundiagnostik AG, Bensheim, Germany) and Promonitor^® ELISA kits (Proteomika, Progenika Biopharma, Bizkaia, Spain)] versus standard care for Crohn's disease (CD).

METHODS

Multiple electronic databases were searched from inception to December 2014 in order to identify primary studies and meta-analyses.

POPULATION

Patients with moderate to severe active CD treated with infliximab (IFX) (Remicade^®, Merck Sharp & Dohme Ltd, Kenilworth, NJ, USA) or adalimumab (ADA) (Humira^®, AbbVie Inc., North Chicago, IL, USA).

INTERVENTION

Monitoring of serum anti-TNF-α (IFX or ADA) and/or of anti-drug antibody levels using test assays with a test-treatment algorithm.

COMPARATOR

Standard care.

OUTCOMES

Any patient-related outcome, test agreement and cost-effectiveness estimates. The quality assessments used recognised checklists (Quality Assessment of Diagnostic Accuracy Studies-2, Cochrane, Philips and Consolidated Health Economic Evaluation Reporting Standards). Evidence was synthesised using narrative review and meta-analysis. A Markov model was built in TreeAge Pro 2013 (TreeAge Software, Inc., Williamstown, MA, USA). The model had a 4-week cycle and a 10-year time horizon, adopted a NHS and Personal Social Services perspective and used a linked evidence approach. Costs were adjusted to 2013/14 prices and discounted at 3.5%.

RESULTS

We included 68 out of 2434 and 4 out of 2466 studies for the clinical effectiveness and cost-effectiveness reviews, respectively. Twenty-three studies comparing test methods were identified. Evidence on test concordance was sparse and contradictory, offering scant data for a linked evidence approach. Three studies [two randomised controlled trials (RCTs) and one retrospective observational study] investigated outcomes following implementation of a test algorithm. None used the specified commercial ELISA immunoassay test kits. Neither of the two RCTs demonstrated clinical benefit of a test-treatment regimen. A meta-analysis of 31 studies to estimate test accuracy for predicting clinical status indicated that 20-30% of test results are likely to be inaccurate. The four cost-effectiveness studies suggested that testing results in small cost reductions. In the economic analysis the base-case analysis showed that standard practice (no testing/therapeutic monitoring with the intervention tests) was more costly and more effective than testing for IFX. Sensitivity and scenario analyses gave similar results. The probabilistic sensitivity analysis indicated a 92% likelihood that the 'no-testing' strategy was cost-effective at a willingness to pay of £20,000 per quality-adjusted life-year.

STRENGTHS AND LIMITATIONS

Rigorous systematic reviews were undertaken; however, the underlying evidence base was poor or lacking. There was uncertainty about a linked evidence approach and a lack of gold standard for assay comparison. The only comparative evidence available for economic evaluation was for assays other than the intervention assays.

CONCLUSIONS

Our finding that testing is not cost-effective for IFX should be viewed cautiously in view of the limited evidence. Clinicians should be mindful of variation in performance of different assays and of the absence of standardised approaches to patient assessment and treatment algorithms.

FUTURE WORK RECOMMENDATIONS

There is substantial variation in the underlying treatment pathways and uncertainty in the relative effectiveness of assay- and test-based treatment algorithms, which requires further investigation. There is very little research evidence on ADA or on drug monitoring in children with CD, and conclusions on cost-effectiveness could not be reached for these.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014015278.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

A Mobile Infliximab Dosing Calculator for Therapy Optimization in Inflammatory Bowel Disease

BACKGROUND

Inadequate infliximab (IFX) drug exposure remains a clinical challenge and leads to high loss of response rates and therapy failure in inflammatory bowel disease (IBD). We aimed to determine the feasibility and pilot effectiveness of a novel, web-based, mobile IFX dosing calculator (mIDC) for therapy optimization.

METHODS

We developed an mIDC leveraging the known clinical variables of C-reative protein (CRP), albumin, patient's weight, disease activity indices, calprotectin, drug trough levels, and antibodies to IFX that significantly affect pharmacokinetics and/or outcomes. A prospective observational cohort study in pediatric and young adult IBD patients receiving maintenance IFX was performed. System-wide practice adoption of mIDC was achieved through a quality improvement (QI) initiative within a hospital-based infusion unit.

RESULTS

Forty-nine patients (median age: 16.0 years; 55% female; 65% Crohn's disease) were followed over 9 months. mIDC recommendations for dose optimization were followed by the treating physicians in 198 (89%) out of 222 infusions. Twenty-eight (13%) of 222 mIDC recommendations were to escalate IFX dosing; 15 (54%) of 28 escalation recommendations were declined, and these patients were more likely to already be receiving IFX dose intensification compared with those in whom escalation recommendations were followed (P < 0.05). From mIDC initiation to end of follow-up, mean albumin levels remained unchanged at 3.8 g/dL. Median CRP remained unchanged at 2 g/L. Median calprotectin levels showed a downward trend from 30 to 27 μg/g (n = 9, P < 0.05). The percentage of patients undergoing therapeutic drug monitoring in clinical care increased from 34% to 86% with the QI initiative. The target median IFX trough goal of >5 μg/mL was achieved with 81% probability throughout the QI initiative, an increase of 12% compared with pre-QI values.

CONCLUSIONS

The use of a novel mIDC is feasible and potentially effective, facilitating both standardization and individualization of therapy in clinical care. mIDC appears to be a practical IFX dosing tool for point-of-care use, leveraging individual pharmacokinetic considerations.

Prediction of Individual Serum Infliximab Concentrations in Inflammatory Bowel Disease by a Bayesian Dashboard System

Despite a robust exposure-response relationship of infliximab in inflammatory bowel disease (IBD), attempts to adjust dosing to individually predicted serum concentrations of infliximab (SICs) are lacking. Compared with labor-intensive conventional software for pharmacokinetic (PK) modeling (eg, NONMEM) dashboards are easy-to-use programs incorporating complex Bayesian statistics to determine individual pharmacokinetics. We evaluated various infliximab detection assays and the number of samples needed to precisely forecast individual SICs using a Bayesian dashboard. We assessed long-term infliximab retention in patients being dosed concordantly versus discordantly with Bayesian dashboard recommendations. Three hundred eighty-two serum samples from 117 adult IBD patients on infliximab maintenance therapy were analyzed by 3 commercially available assays. Data from each assay was modeled using NONMEM and a Bayesian dashboard. PK parameter precision and residual variability were assessed. Forecast concentrations from both systems were compared with observed concentrations. Infliximab retention was assessed by prediction for dose intensification via Bayesian dashboard versus real-life practice. Forecast precision of SICs varied between detection assays. At least 3 SICs from a reliable assay are needed for an accurate forecast. The Bayesian dashboard performed similarly to NONMEM to predict SICs. Patients dosed concordantly with Bayesian dashboard recommendations had a significantly longer median drug survival than those dosed discordantly (51.5 versus 4.6 months, P < .0001). The Bayesian dashboard helps to assess the diagnostic performance of infliximab detection assays. Three, not single, SICs provide sufficient information for individualized dose adjustment when incorporated into the Bayesian dashboard. Treatment adjusted to forecasted SICs is associated with longer drug retention of infliximab.

Obesity and Pediatric Drug Development

There is a lack of dosing guidelines for use in obese children. Moreover, the impact of obesity on drug safety and clinical outcomes is poorly defined. The paucity of information needed for the safe and effective use of drugs in obese patients remains a problem, even after drug approval. To assess the current incorporation of obesity as a covariate in pediatric drug development, the pediatric medical and clinical pharmacology reviews under the Food and Drug Administration (FDA) Amendments Act of 2007 and the FDA Safety and Innovation Act (FDASIA) of 2012 were reviewed for obesity studies. FDA labels were also reviewed for statements addressing obesity in pediatric patients. Forty-five drugs studied in pediatric patients under the FDA Amendments Act were found to have statements and key words in the medical and clinical pharmacology reviews and labels related to obesity. Forty-four products were identified similarly with pediatric studies under FDASIA. Of the 89 product labels identified, none provided dosing information related to obesity. The effect of body mass index on drug pharmacokinetics was mentioned in only 4 labels. We conclude that there is little information presently available to provide guidance related to dosing in obese pediatric patients. Moving forward, regulators, clinicians, and the pharmaceutical industry should consider situations in drug development in which the inclusion of obese patients in pediatric trials is necessary to facilitate the safe and effective use of new drug products in the obese pediatric population.

Inflammatory bowel disease: towards a personalized medicine

The management of inflammatory bowel disease (IBD) has been transformed over the last two decades by the arrival of tumor necrosis factor (TNF) antagonist agents. Recently, alternative drugs have been approved, directed at leukocyte-trafficking molecules (vedolizumab) or other inflammatory cytokines (ustekinumab). New therapeutics are currently being developed in IBD and represent promising targets as they involve other mechanisms of action (JAK molecules, Smad 7 antisense oligonucleotide etc.). Beyond TNF antagonist agents, these alternative drugs are needed for early-stage treatment of patients with aggressive IBD or when the disease is resistant to conventional therapy. Personalized medicine involves the determination of patients with a high risk of progression and complications, and better characterization of patients who may respond preferentially to specific therapies. Indeed, more and more studies aim to identify factors predictive of drug response (corresponding to a specific signaling pathway) that could better manage treatment for patients with IBD. Once treatment has started, disease monitoring is essential and remote patient care could in some circumstances be an attractive option. Telemedicine improves medical adherence and quality of life, and has a positive impact on health outcomes of patients with IBD. This review discusses the current application of personalized medicine to the management of patients with IBD and the advantages and limits of telemedicine in IBD.

Exposure-response relationship of certolizumab pegol induction and maintenance therapy in patients with Crohn's disease

BACKGROUND

Therapeutic drug monitoring may optimize therapy for Crohn's disease (CD).

AIM

To use a population pharmacokinetic model that accounts for the time-varying nature of covariates to simulate certolizumab pegol (CZP) concentrations to evaluate the exposure-response relationship for CZP in Crohn's disease.

METHODS

Adults (N = 2157) with Crohn's disease were treated with CZP in nine clinical trials. Simulated CZP concentrations were compared to outcomes at weeks 6 and 26, including Crohn's disease activity index (CDAI) response (decrease from baseline ≥ 100 points), remission (CDAI ≤ 150), C-reactive protein (CRP) ≤ 5 mg/L, faecal calprotectin (FC) ≤ 250 μg/g, and a composite endpoint of CDAI ≤ 150 and FC ≤ 250 μg/g. Multivariable analyses identified covariates associated with outcomes and receiver operating characteristic analyses determined optimal CZP concentrations.

RESULTS

CZP concentrations at weeks 2, 4 and 6 were higher in patients with clinical response, remission, CRP ≤ 5 mg/L or FC ≤ 250 μg/g at week 6 than without. In multivariable analyses, higher CZP concentrations at week 6 were associated with the composite outcome at weeks 6 and 26 (P < .001). Although the exposure-response relationship varied among patients, approximate CZP concentrations of at least 36.1 μg/mL (positive predictive value [PPV] 22.8% and negative predictive value [NPV] 92.7%) and at least 14.8 μg/mL (PPV 28.0% and NPV 90.4%) at weeks 6 and 12 were associated with weeks 6 and 26 outcomes.

CONCLUSIONS

An exposure-response relationship was apparent for CZP in Crohn's disease and achieving higher CZP concentrations may increase the likelihood of attaining efficacy outcomes, but this remains to be evaluated prospectively.

Dosing down and then discontinuing biologic therapy in rheumatoid arthritis: a review of the literature

AIM

To review the published studies that dose down and then discontinue biologic therapy in patients with rheumatoid arthritis (RA), particularly concerning the criteria for such dosing and the impact on clinical outcomes.

METHODS

Published studies conducted in patients with RA that sequentially decreased the dose and then discontinued therapy were included if one or more of the following biologic disease modifying antirheumatic drugs (bDMARDs) was evaluated: abatacept, adalimumab, certolizumab, etanercept, golimumab, infliximab, rituximab or tocilizumab.

RESULTS

Five studies qualified for inclusion. The populations of patients with RA were heterogeneous among the studies; patients were required to have low disease activity (LDA) or to be in remission prior to dose titration. Approximately 25-65% of patients successfully decreased and in some cases, discontinued the bDMARD. However, the flare rate was higher than for the patients who remained on a standard dose. The only variable that predicted relapse in more than one study was down-titration of the bDMARD dose.

CONCLUSION

In patients who have achieved LDA or remission, down-titration and discontinuation of bDMARD therapy may be attempted, with careful monitoring. However, it is likely that some patients will flare, and it is not known how to predict these patients.

Review article: consensus statements on therapeutic drug monitoring of anti-tumour necrosis factor therapy in inflammatory bowel diseases

BACKGROUND

Therapeutic drug monitoring (TDM) in inflammatory bowel disease (IBD) patients receiving anti-tumour necrosis factor (TNF) agents can help optimise outcomes. Consensus statements based on current evidence will help the development of treatment guidelines.

AIM

To develop evidence-based consensus statements for TDM-guided anti-TNF therapy in IBD.

METHODS

A committee of 25 Australian and international experts was assembled. The initial draft statements were produced following a systematic literature search. A modified Delphi technique was used with 3 iterations. Statements were modified according to anonymous voting and feedback at each iteration. Statements with 80% agreement without or with minor reservation were accepted.

RESULTS

22/24 statements met criteria for consensus. For anti-TNF agents, TDM should be performed upon treatment failure, following successful induction, when contemplating a drug holiday and periodically in clinical remission only when results would change management. To achieve clinical remission in luminal IBD, infliximab and adalimumab trough concentrations in the range of 3-8 and 5-12 μg/mL, respectively, were deemed appropriate. The range may differ for different disease phenotypes or treatment endpoints-such as fistulising disease or to achieve mucosal healing. In treatment failure, TDM may identify mechanisms to guide subsequent decision-making. In stable clinical response, TDM-guided dosing may avoid future relapse. Data indicate drug-tolerant anti-drug antibody assays do not offer an advantage over drug-sensitive assays. Further data are required prior to recommending TDM for non-anti-TNF biological agents.

CONCLUSION

Consensus statements support the role of TDM in optimising anti-TNF agents to treat IBD, especially in situations of treatment failure.

Therapeutic Drug Monitoring in Inflammatory Bowel Disease: History and Future Directions

Clinical trials for the most effective drugs in the armamentarium of medications for inflammatory bowel disease (IBD) have shown only a 50-60% response rate, and this drops to 30% in maintenance. However, therapeutic drug monitoring (TDM) to adjust dosing to account for patient-specific characteristics, which has been shown to improve outcomes, was not utilized in these trials. This review will detail the development of TDM within the IBD space as it evolved from thiopurines to biologics and continues to evolve with loftier treat-to-target goals and more sophisticated dashboard systems.

C-reactive protein as a predictor of low trough infliximab concentrations in patients who lose response to infliximab

OBJECTIVE

Low serum infliximab concentrations are associated with an increased risk of loss of response in inflammatory bowel disease (IBD). The objective of this study was to evaluate the test characteristics of C-reactive protein (CRP) in identifying low serum infliximab concentrations in patients with IBD.

METHODS

We measured serum infliximab concentrations and CRP levels in patients who experienced deteriorating symptoms while on infliximab (the reactive cohort). Receiver operating characteristic (ROC) curves were used to determine the CRP concentration threshold that identified an infliximab concentration <3 μg/mL at the time of loss of response. These CRP thresholds for infliximab concentration <3 μg/mL were then tested in a separate validation cohort.

RESULTS

The reactive cohort contained 111 patients and the validation cohort contained 139 patients. In 41% of participants, serum infliximab concentration was <3 μg/mL. In the reactive cohort, the area under the ROC curve for CRP to identify an infliximab concentration <3 μg/mL was 0.70 (95% confidence interval [CI] 0.50-0.80, P = 0.02). A CRP level above 12 mg/L in the preceding 90 days provided a 90% specificity for the later detection of infliximab concentration <3 μg/mL. These test characteristics were similar in the validation cohort.

CONCLUSION

CRP levels over 12 mg/L exhibit a high specificity for identifying patients with an infliximab concentration <3 μg/mL. CRP may be cost-effective for identifying patients with low concentrations of infliximab at the time of, or at risk of, loss of response.

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.

Distinct Thresholds of Infliximab Trough Level Are Associated with Different Therapeutic Outcomes in Patients with Inflammatory Bowel Disease: A Prospective Observational Study

BACKGROUND

Several studies have reported a strong correlation between infliximab (IFX) trough levels (trough levels of infliximab [TLI]) and clinical remission (CR). We aimed to determine threshold values of TLI associated with the occurrence of CR, with or without normal inflammatory biomarkers, including serum C-reactive protein (CRP) and fecal calprotectin (fCal).

METHODS

We included prospectively all consecutive patients with inflammatory bowel disease under IFX therapy (5 mg/kg every 8 wk) for at least 6 months. Disease activity (using the Crohn's Disease Activity Index or Mayo score) was recorded, and TLI, CRP, and fCal were measured before IFX infusion.

RESULTS

Two hundred thirteen patients (131 Crohn's disease) were included. The median TLIs were higher in patients who achieved CR compared with those in patients who did not (2.6 versus 1.2 μg/mL, P < 0.01). The median TLI were higher in patients achieving CR with CRP normalization or CR with fCal <250 μg/g in comparison with patients with persistent elevated CRP or fCal (3.5 versus 1.6 μg/mL, P < 0.01 and 4.9 versus 1.8 μg/mL, P < 0.001, respectively). Finally, the median TLIs were higher in patients achieving CR with normal CRP and fCal <50 μg/g in comparison with patients without strictly normal biomarkers (5.9 versus 2.1 μg/mL, P < 0.001). The more the expected level of response to IFX was stringent, the more the median TLI and optimal thresholds were high.

CONCLUSIONS

Threshold values of TLI differ according to therapeutic outcomes expected in patients with inflammatory bowel disease under maintenance therapy with IFX.

Concomitant Therapy with Immunomodulator Enhances Infliximab Durability in Pediatric Inflammatory Bowel Disease

BACKGROUND

Data on long-term durability of infliximab (IFX) and outcomes of concomitant therapy with immunomodulator in pediatric inflammatory bowel disease are limited.

METHODS

Children with inflammatory bowel disease who received IFX ± immunomodulator were retrospectively reviewed. Predictors of induction response were assessed using a binary logistic regression model and long-term outcomes evaluated by Cox proportional hazards model. Propensity score matching examined long-term efficacy of concomitant therapy in patients with Crohn's disease (CD).

RESULTS

Among 148 patients (113 CD, 35 ulcerative colitis; median age at IFX initiation 14.09 years [interquartile range 12.16-15.65]), 91% experienced response to induction therapy; patients with CD were more likely to respond (95% versus 77%, odds ratio = 2.63, 95% confidence interval, 1.01-6.85, P = 0.048). Despite dose optimization, secondary loss of response occurred at a rate of 9.01% and 8.33% per year for patients with CD and ulcerative colitis, respectively. A Cox proportional hazards model showed that concomitant therapy >6 months significantly lowered the risk of secondary loss of response in CD (hazard ratio = 0.39, 95% confidence interval, 0.17-0.88, P = 0.025). The same trend was observed in ulcerative colitis but did not reach significance. A higher proportion of patients on IFX monotherapy stopped IFX because of loss of response or infusion reactions (55% versus 21%, P < 0.001). Propensity score analysis of patients with CD showed significantly higher steroid-free remission rates for concomitant versus monotherapy at 1 year (78% versus 54%, P = 0.020) and 2 years (68% versus 46%, P = 0.044), and durability of response (P = 0.022).

CONCLUSIONS

These data demonstrate sustained efficacy of IFX in a cohort of pediatric patients with inflammatory bowel disease with durability of response enhanced by concomitant therapy.

Adherence to infliximab therapy in inflammatory bowel disease patients in a real-life setting

OBJECTIVE

To assess adherence to infliximab (IFX) therapy in inflammatory bowel disease patients, to investigate reasons for non-adherence and to identify predictors for non-adherence.

METHODS

This observational study was conducted in two French referral university hospitals between 1 September and 31 October, 2011. Patients were systematically asked if they had already delayed or missed an IFX perfusion since the beginning of the treatment and about the reasons for their non-adherence.

RESULTS

Of the 162 included patients (121 Crohn's disease [CD], 41 ulcerative colitis), 87 (53.7%) reported a delay of at least one IFX injection and 14 (8.6%) missed at least one IFX perfusion since the beginning of the treatment. The overall non-adherence rate was 54.3%. Pooling all misses, the main reasons for non-adherence were pregnancy (33.3%), intentional non-adherence (20%) and forgetfulness (13.3%). Pooling all delays, the main reasons for non-adherence were professional constraints (46.9%), infections (17.3%) and travels (14.3%). Perineal disease was associated with IFX delays (P = 0.0007, odds ratio 4.0), whereas active CD/UC was associated with IFX misses (P = 0.0258, OR = 5.4).

CONCLUSIONS

The overall non-adherence rate for IFX use was 54.3%. Professional constraints and intentional non-adherence were the leading causes of non-adherence. Perineal disease and active CD were negatively related to adherence.

Serum Interleukin 9 Levels Predict Disease Severity and the Clinical Efficacy of Infliximab in Patients with Crohn's Disease

BACKGROUND

Interleukin (IL)-9 drives gut inflammation, but its role in Crohn's disease (CD) is unclear. We aimed to analyze correlations between serum IL-9 levels and disease severity and to evaluate their predictive value in relation to the clinical efficacy of infliximab (IFX) in patients with CD.

METHODS

Between January 2013 and December 2015, 100 consecutive patients with active CD and 50 age- and sex-matched control individuals were recruited from a tertiary center. Their serum IL-9 levels were measured using an enzyme-linked immunosorbent assay. Correlations between the serum IL-9 levels and disease severity were examined. The serum IL-9 level was explored as a predictor of clinical remission and mucosal healing at week 30 in 50 patients for whom IFX therapy was administered.

RESULTS

The serum IL-9 levels were significantly higher in the patients with active CD (22.0 pg/mL) than in the control individuals (6.3 pg/mL) (P < 0.001); they differed according to disease severity (moderate-to-severe CD: 29.1 pg/mL versus mild CD: 12.9 pg/mL) (P < 0.001), and they correlated well with the clinical activity of CD. IFX lowered the serum IL-9 level in patients who achieved efficacy at week 30. The areas under the curves for the IL-9 levels at weeks 14 and 30 that could predict clinical remission and mucosal healing at week 30 were 0.803 and 0.752 and 0.746 and 0.781, respectively.

CONCLUSIONS

Serum IL-9 levels correlate with disease severity and the clinical efficacy of IFX in patients with CD, and IL-9 may be a promising novel biomarker for CD monitoring.

Dietary Therapy With the Crohn's Disease Exclusion Diet is a Successful Strategy for Induction of Remission in Children and Adults Failing Biological Therapy

BACKGROUND

Loss of response [LoR] to biologics in Crohn's disease [CD] is a significant clinical problem. Dietary therapy as a treatment strategy in this setting has not been previously reported. We report the use of dietary strategies using enteral nutrition coupled with the Crohn's Disease Exclusion Diet [CDED] for LoR to infliximab or adalimumab as a single-centre experience.

METHODS

Patients with LoR to a biologic despite dose escalation or combination therapy were treated with partial enteral nutrition [PEN] by a polymeric formula and the CDED for 12 weeks. Paediatric patients with severe flares received 14 days of exclusive enteral nutrition followed by PEN + CDED as above. All patients were seen at weeks 6 and 12 for follow up. Current and prior treatment, Harvey Bradshaw Index [HBI], C-reactive protein [CRP] and albumin were recorded. Remission was defined as HBI <5 at week 6.

RESULTS

Twenty-one patients, mean age 22.1 ± 8.9 years [11 adults and ten children] met study criteria. Seventeen patients [81%] had used combination therapy, and 10/21 [47.6%] had failed a second biologic. Seven patients had a prior intestinal resection. Dose escalation had failed in 13/21 [62%] patients. Clinical remission by physician's global assessment and HBI after 6 weeks was obtained in 13/21 [61.9%]. Mean HBI decreased from 9.4 ± 4.2 to 2.6 ± 3.8 [p < 0.001], mean CRP decreased from 2.8 ± 3.4 to 0.7 ± 0.5 [p = 0.005] and mean albumin increased from 3.5 ± 0.6 to 3.8 ± 0.5 [p = 0.06].

CONCLUSION

Dietary treatment combining PEN with the CDED may be a useful salvage regimen for patients failing biological therapy despite dose escalation.

IMPORTANCE OF MEASURING LEVELS OF INFLIXIMAB IN PATIENTS TREATING INFLAMMATORY BOWEL DISEASE IN A BRAZILIAN COHORT

BACKGROUND

Crohn's disease and ulcerative colitis are chronic inflammatory bowel diseases. In such pathologies, there is an increased production of alpha tumor necrosis factor (TNF-α). Patients, in whom the conventional immunosuppressant treatment fails, require the use of immunobiological therapy, such as anti-TNF-α, a monoclonal antibody. Infliximab is an anti-TNF-α drug, a chimerical immunoglobulin, with a murine component, which is responsible for the generation of immunogenicity against the drug and formation of anti-TNF-α antibodies. The presence of anti-drug antibodies may be responsible for adverse events and reduction of the drug's effectiveness. Patients with inflammatory bowel diseases undergoing therapy with biological medication, such as infliximab, can relapse overtime and this may not be translated into clinical symptoms. Thus, there is a need for a method to evaluate the efficacy of the drug, through the measurement of serum infliximab levels, as well as antibodies research.

OBJECTIVE

This study aimed to measure serum infliximab levels and anti-infliximab antibodies in patients with inflammatory bowel diseases post-induction phase and during maintenance therapy, and describe the therapeutic modifications that took place based on the serum levels results.

METHODS

It was a retrospective study, that included forty-five patients, with a total of 63 samples of infliximab measurement.

RESULTS

Twenty-one patients had an adequate infliximab serum level, 31 had subtherapeutic levels and 11 had supratherapeutic levels. Seven patients had their medication suspended due to therapeutic failure or high levels of antibodies to infliximab.

CONCLUSION

In conclusion, only a third of the patients had adequate infliximab levels and 36% presented with subtherapeutic levels at the end of the induction phase. Therapy optimization occurred based in about 46% of the samples results, demonstrating the importance of having this tool to help the clinical handling of patients with inflammatory bowel diseases ongoing biologic therapy.

The Evolving Evidence for Therapeutic Drug Monitoring of Monoclonal Antibodies in Inflammatory Bowel Disease

PURPOSE OF REVIEW

Biological medications are effective in inflammatory bowel disease (IBD) but adverse events, cost, and loss of response make their use challenging. Therapeutic drug monitoring (TDM) allows clinicians to more safely, effectively, and efficiently use medications. The purpose of this article is to review and summarize the most recent literature pertaining to TDM in IBD.

RECENT FINDINGS

Measurement of biological drug trough levels predicts ongoing patient response and can be used to titrate the medication to be more effective and efficient. Antibodies against the medications predict loss of response and adverse events. Using both parameters can predict response to subsequent biologicals. Newer biologicals show similar characteristics to those more commonly used. Management protocols using drug and antibody levels optimize medication use and may be cost-effective. Recent evidence suggests benefit to TDM of biologicals in IBD.

Primary and secondary nonresponse to infliximab: mechanisms and countermeasures

INTRODUCTION

Primary and secondary non-response to infliximab are common in patients with inflammatory bowel disease and remain a management challenge in clinical practice. Areas covered: This article describes the epidemiology, mechanisms and risk factors for primary and secondary nonresponse to infliximab in patients with inflammatory bowel disease. Data on proactive and reactive therapeutic drug monitoring are examined in this review. An algorithm for evaluation and management of non-response to infliximab is provided. Preventative measures are also discussed. Relevant articles were identified after a literature search using PubMed. Search terms included 'infliximab', 'loss of response', 'immunogenicity', and 'drug monitoring'. References of identified articles were also reviewed to identify additional references. Expert opinion: A common cause for primary and secondary non-response include inadequate dosing of infliximab; inadequate dosing can be identified through assessment of drug and anti-drug antibody levels. Therapeutic drug monitoring should be done in patients losing response to infliximab. Use of drug monitoring proactively is still under debate.

Clinical performance of an infliximab rapid quantification assay

BACKGROUND

Therapeutic drug monitoring (TDM)-based algorithms can be used to guide infliximab (IFX) adjustments in inflammatory bowel disease (IBD) patients. This study aimed to explore a rapid IFX-quantification test from a clinical perspective.

METHODS

This manuscript describes a prospective cohort study involving 110 ulcerative colitis (UC) patients on the maintenance phase of IFX. IFX trough levels were quantified using a rapid quantification assay and a commonly-used reference kit.

RESULTS

Irrespective of the assay used to measure IFX, its through levels were statistically different between patients with and without endoscopic remission (Mayo endoscopic score = 0), as well as between patients stratified by their faecal calprotectin (FC) levels. Despite the fact that the two methods correlated well with each other [Spearman's rank correlation coefficient = 0.843, p < 0.001; intraclass correlation coefficients = 0.857, 95% confidence interval (CI): 0.791-0.903], there was a discernible systematic variation; values obtained with the reference kit were on average 2.62 units higher than those obtained with the rapid assay. Notwithstanding, 3 µg/ml was shown to be an acceptable cut-off to assess endoscopic status and inflammatory burden levels using both assays. The percentage of patients that had a positive outcome when the IFX concentration measured by the rapid assay ranked above 3 µg/ml was 88% both for a Mayo endoscopic score ⩽ 1 and for an FC concentration <250 µg/g.

CONCLUSIONS

Based on this study, we concluded that using the rapid IFX assessment system with a 3 µg/ml threshold is a reliable alternative to the time-consuming enzyme-linked immunosorbent assays in patients on the maintenance phase of IFX.

Therapeutic drug monitoring of CT-P13: a comparison of four different immunoassays

BACKGROUND

The commercialization of CT-P13, an infliximab (IFX) biosimilar, has the potential to decrease health-related costs and enhance access to biological therapies. This study aimed to address the accuracy and inter-assay agreement of the CT-P13 quantification using four different assays initially developed to assess IFX.

METHODS

The four different methods, one in-house method and three commercially available kits, were used to quantify exogenously-spiked samples and the sera from 185 inflammatory bowel disease (IBD) patients on CT-P13 therapy.

RESULTS

The quantification of the spiked samples unveiled a consistent and accurate behaviour of three of the tested methods, with average percentage recoveries of 90%, 102% and 109%. Results from the clinical samples demonstrated that these three assays were also highly correlated, both concerning Spearman's rank coefficients (range 0.890-0.947) and intraclass correlation coefficients (range 0.907-0.935). There were a few systematic deviations among them, but their impact in the clinical stratification of the patients using different cut-offs was minimal, particularly when these cut-offs were in the 3-4 µg/ml range, for which the strength of agreement (as assessed by the Kappa statistics that ranged from 0.732 to 0.902) was substantial to almost perfect.

CONCLUSIONS

Our results indicate that three of the tested IFX quantification methods can be used to accurately quantify CT-P13 without any adjustments.

Effects of Combination Therapy With Immunomodulators on Trough Levels and Antibodies Against Tumor Necrosis Factor Antagonists in Patients With Inflammatory Bowel Disease: A Meta-analysis

BACKGROUND & AIMS

It is not clear whether combination therapy with immunomodulators affects the immunogenicity of tumor necrosis factor (TNF) antagonists in patients with inflammatory bowel disease. We performed a meta-analysis to quantify the effects of combined immunomodulator therapy on the presence of antibodies against TNF antagonists (antidrug antibodies [ADAs]) and trough levels of anti-TNF agents.

METHODS

We systematically searched publication databases for studies that reported prevalence of ADAs in patients who received anti-TNF agents. Raw data from studies that met the inclusion criteria were pooled to determine effect estimates. We performed subgroup and metaregression analyses to determine the level of heterogeneity among study outcomes.

RESULTS

We analyzed findings from 35 studies that met inclusion criteria (results reported from 6790 patients with inflammatory bowel disease). The pooled risk ratio for formation of ADAs in patients receiving combined therapy with immunomodulators, versus that of patients receiving anti-TNF monotherapy, was 0.49 (95% confidence interval, 0.41-0.59; P < .001). However, the pooled analysis did not demonstrate a significant difference in trough levels of anti-TNF agents between patients with versus without concurrent use of immunomodulators (standardized mean difference, 0.11; 95% confidence interval, 0.19-0.41; P = .47). Subgroup analyses of patients treated with different TNF antagonists revealed no difference in the formation of ADAs (P = .50 for interaction); the protective effect of immunomodulators did not differ with type of drug patients were given (methotrexate vs thiopurines), or assay for ADA. We observed heterogeneity only among studies of patients with ulcerative colitis (I² = 76%). Funnel plot and Egger test analyses indicated publication bias in the studies (P = .001).

CONCLUSIONS

In a meta-analysis of published studies, we associated combined treatment with immunomodulators with reduced risk of formation of antibodies against TNF antagonists in patients with inflammatory bowel disease.

Update on Therapeutic Drug Monitoring in Crohn's Disease

In patients with Crohn's disease on biologic medications, the use of therapeutic drug monitoring leads to a personalized approach to optimize treatment. Using an algorithmic approach, measurement of drug concentrations and anti-drug antibodies can be used to improve treatment outcomes. Therapeutic drug concentrations and absence of antibodies are associated with improved clinical and endoscopic outcomes. In clinical practice, therapeutic drug monitoring has been shown to be clinically useful and cost-effective in patients experiencing a loss of response to treatment. This review highlights the available data on therapeutic drug monitoring in the treatment of patients with Crohn's disease on biologic medications.

Evolution after switching to biosimilar infliximab in inflammatory bowel disease patients in clinical remission

BACKGROUND AND AIM

The biosimilar of infliximab (CT-P13) has been approved for the same indications held by the infliximab reference product (Remicade^®); however, there are few clinical data on switching in inflammatory bowel disease (IBD). The aim of this study was to assess the efficacy, safety, bioavailability profile and factors associated with relapse after switching to biosimilar infliximab in IBD patients in clinical remission.

MATERIAL AND METHOD

Observational study with IBD patients treated with Remicade^® for at least 6 months and in clinical remission for at least 3 months who switched to infliximab biosimilar. The incidence of relapse, adverse effects and possible changes in drug bioavailability (trough level and antidrug antibodies) were evaluated.

RESULTS

Thirty six patients were included (63.9% CD) with a mean follow-up of 8.4 months (SD±3.5). The 13.9% had clinical relapse. The longer clinical remission time before switching (HR=0.54, 95% CI=0.29-0.98, P=.04) and detectable infliximab levels at the time of switching (HR=0.03, 95% CI=0.001-0.89, P=.04) were associated with a lower risk of relapse. No differences were found between infliximab levels at the time of switching and at weeks 8 and 16 (P=.94); 8.3% of the patients had some adverse event, requiring the suspension of biosimilar in one patient for severe pneumonia.

CONCLUSION

Switching to biosimilar infliximab in a real-life cohort of IBD patients in clinical remission did not have a significant impact on short-term clinical outcomes. The factors associated with relapse were similar to those expected in patients continuing with Remicade^®.

Strategies for overcoming anti-tumor necrosis factor drug antibodies in inflammatory bowel disease: Case series and review of literature

Anti-tumor necrosis factor (TNF) biologics are currently amongst the most widely used and efficacious therapies for inflammatory bowel disease (IBD). The development of therapeutic drug monitoring for infliximab and adalimumab has allowed for measurement of drug levels and antidrug antibodies. This information can allow for manipulation of drug therapy and prediction of response. It has been shown that therapeutic anti-TNF drug levels are associated with maintenance of remission, and development of antidrug antibodies is predictive of loss of response. Studies suggest that a low level of drug antibodies, however, can at times be overcome by dose escalation of anti-TNF therapy or addition of an immunomodulator. We describe a retrospective case series of twelve IBD patients treated at the University of California-Irvine, who were on infliximab or adalimumab therapy and were found to have detectable but low-level antidrug antibodies. These patients underwent dose escalation of the drug or addition of an immunomodulator, with subsequent follow-up drug levels obtained. Eight of the twelve patients (75%) demonstrated resolution of antidrug antibodies, and were noted to have improvement in disease activity. Though data regarding overcoming low-level anti-TNF drug antibodies remains somewhat limited, cases described in the literature as well as our own experience suggest that this may be a viable strategy for preserving the use of an anti-TNF drug. Low-level anti-TNF drug antibodies may be overcome by dose escalation and/or addition of an immunomodulator, and can allow for clinical improvement in disease status. Therapeutic drug monitoring is an important tool to guide this strategy.

Clinical Use of Measuring Trough Levels and Antibodies against Infliximab in Patients with Pediatric Inflammatory Bowel Disease

Background/Aims

The clinical use of measuring infliximab (IFX) trough levels (TLs) and antibodies against IFX (ATIs) in patients with pediatric inflammatory bowel disease (IBD) remains unclear. We propose measuring these variables to create individual IFX treatment strategies for patients with pediatric IBD.

Methods

This retrospective study was conducted in pediatric patients with IBD who received IFX from July 2009 to June 2014.

Results

Samples were available from 39 patients with pediatric IBD. A significant difference was observed in IFX TLs in 16 patients who were in clinical remission (group A) after IFX therapy (median, 3.99 μg/mL; interquartile range [IQR], 0.30 to 21.96) compared to 23 patients who had a poor response to treatment (group B) (median, 0.88 μg/mL; IQR, 0.00 to 6.80, p=0.002). In group B, 21 patients underwent empiric intensification of IFX treatment. After dose intensification, 17 patients had an improved response to treatment. Four patients still had no response to dose intensification. Therefore, these patients were switched to other biologics.

Conclusions

Patients who had poor responses and subtherapeutic IFX TLs had an improved response to dose intensification. Patients who had ATIs were likely to continue to have no response after dose intensification. Therefore, tailoring individual IFX treatments based on IFX TLs, ATIs, and the clinical response should be considered.

Exposure-efficacy Relationships for Vedolizumab Induction Therapy in Patients with Ulcerative Colitis or Crohn's Disease

BACKGROUND AND AIMS

A positive relationship between vedolizumab trough serum concentrations and clinical outcomes in patients with ulcerative colitis [UC] or Crohn's disease [CD] has been reported. Here we further explore exposure-efficacy relationships for vedolizumab induction therapy in post hoc analyses of GEMINI study data.

METHODS

Vedolizumab trough concentrations at Week 6 or 10 were grouped in quartiles and clinical outcome rates calculated. Exposure-efficacy relationships at Week 6 and potential baseline covariate effects were explored using logistic regression and individual predicted cumulative average concentration through Week 6 [Caverage] as exposure measure.

RESULTS

Higher vedolizumab concentrations were associated with higher clinical remission rates; the exposure-efficacy relationship was steeper for UC than CD. Unadjusted analyses overestimated the relationship, more so for CD. From covariate-adjusted models, average probability of remission at Week 6 increased by approximately 15% for UC and 10% for CD between Caverage values of 35 and 84 µg/ml [5th and 95th percentiles, respectively]. On average, patients with higher albumin, lower faecal calprotectin [UC only], lower C-reactive protein [CD only], and no previous tumour necrosis factor-α [TNFα] antagonist use had a higher remission probability. Previous TNFα antagonist use had the greatest impact; remission probability was approximately 10% higher in treatment-naïve patients.

CONCLUSIONS

Higher vedolizumab serum concentrations were associated with higher remission rates after induction therapy in patients with moderately to severely active UC or CD. This relationship is affected by several factors, including previous TNFα antagonist use. Prospective studies are needed to assess vedolizumab dose individualisation and optimisation.

Test accuracy of drug and antibody assays for predicting response to antitumour necrosis factor treatment in Crohn's disease: a systematic review and meta-analysis

OBJECTIVE

To present meta-analytic test accuracy estimates of levels of antitumour necrosis factor (anti-TNF) and antibodies to anti-TNF to predict loss of response or lack of regaining response in patients with anti-TNF managed Crohn's disease.

METHODS

MEDLINE, Embase, the Cochrane Library and Science Citation Index were searched from inception to October/November 2014 to identify studies which reported 2×2 table data of the association between levels of anti-TNF or its antibodies and clinical status. Hierarchical/bivariate meta-analysis was undertaken with the user-written 'metandi' package of Harbord and Whiting using Stata V.11 software, for infliximab, adalimumab,anti-infliximab and anti-adalimumab levels as predictors of loss of response. Prevalence of Crohn's disease in included studies was meta-analysed using a random effects model in MetaAnalyst software to calculate positive and negative predictive values. The search was updated in January 2017.

RESULTS

31 studies were included in the review. Studies were heterogeneous with respect to the type of test used, criteria for establishing response and loss of response, population examined and results. Meta-analytic summary point estimates for sensitivity and specificity were 65.7% and 80.6% for infliximab trough levels and 56% and 79% for antibodies to infliximab, respectively. Pooled results for adalimumab trough levels and antibodies to adalimumab were similar. Pooled positive and negative predictive values ranged between 70% and 80% implying that between 20% and 30% of both positive and negative test results may be incorrect in predicting loss of response.

CONCLUSION

The available evidence suggests that these tests have modest predictive accuracy for clinical status; direct test accuracy comparisons in the same population are needed. More clinical trial evidence from test-treat studies is required before the clinical utility of the tests can be reliably evaluated.

Azathioprine dose reduction in inflammatory bowel disease patients on combination therapy: an open-label, prospective and randomised clinical trial

BACKGROUND

Infliximab (IFX) combined with azathioprine (AZA) is more effective than IFX monotherapy in inflammatory bowel disease (IBD).

AIM

To identify the AZA optimal dose that is required for efficacy when receiving combination therapy.

METHODS

Patients with IBD in durable remission on combination therapy were enrolled in a 1-year, open-label, prospective trial after randomisation into three groups: AZA steady (2-2.5 mg/kg/day, n=28) vs AZA down (dose was halved 1-1.25 mg/kg/day, n=27) vs AZA stopped (n=26). Primary endpoint was failure defined as occurrence of a clinical relapse and/or any change in IBD therapy.

RESULTS

Eighty-one patients were included. Five (17.9%), 3 (11.1%), and 8 (30.8%) patients experienced failure at 1 year in groups AZA steady, AZA down and AZA stopped, respectively (P=.1 across the groups). The median trough levels of IFX at inclusion were close to those measured at the end of follow-up in group AZA steady (3.65 vs 3.45 μg/mL, P=.9) and in group AZA down (3.95 vs 3.60 μg/mL, P=.5), whereas these levels dropped from 4.25 to 2.15 μg/mL (P=.02) in group AZA stopped. Four (14.3%), four (14.8%) and 11 (42.3%) patients experienced an unfavourable evolution of IFX pharmacokinetics in groups AZA steady, AZA down and AZA stopped, respectively. A threshold of 6-TGN <105 pmoles/8.10⁸ RBC was associated with an unfavourable evolution of IFX pharmacokinetics.

CONCLUSIONS

Under combination therapy, AZA dose reduction, but not withdrawal, appears to be as effective as continuation of AZA at full dose.

Infliximab and adalimumab drug levels in Crohn's disease: contrasting associations with disease activity and influencing factors

BACKGROUND

Discriminative drug level thresholds for disease activity endpoints in patients with Crohn's disease. have been consistently demonstrated with infliximab, but not adalimumab.

AIMS

To identify threshold concentrations for infliximab and adalimumab in Crohn's disease according to different disease endpoints, and factors that influence drug levels.

METHODS

We performed a cross-sectional service evaluation of patients receiving maintenance infliximab or adalimumab for Crohn's disease. Serum drug levels were at trough for infliximab and at any time point for adalimumab. Endpoints included Harvey-Bradshaw index, C-reactive protein and faecal calprotectin. 6-tioguanine nucleotide (TGN) concentrations were measured in patients treated with thiopurines.

RESULTS

A total of 191 patients (96 infliximab, 95 adalimumab) were included. Differences in infliximab levels were observed for clinical (P=.081) and biochemical remission (P=.003) and faecal calprotectin normalisation (P<.0001) with corresponding thresholds identified on ROC analysis of 1.5, 3.4 and 5.7 μg/mL. Adalimumab levels were similar between active disease and remission regardless of the endpoint assessed. Modelling identified that higher infliximab dose, body mass index and colonic disease independently accounted for 31% of the variation in infliximab levels, and weekly dosing, albumin and weight accounted for 23% of variation in adalimumab levels. TGN levels did not correlate with drug levels.

CONCLUSIONS

Infliximab drug levels are associated with the depth of response/remission in patients with Crohn's disease, but no such relationship was observed for adalimumab. More data are needed to explain the variation in drug levels.

Utilisation of anti-TNF levels in a UK tertiary IBD centre

OBJECTIVE

To ascertain how anti-tumour necrosis factor (TNF) drug and anti-drug antibody levels testing is used in a 'real-world' setting to optimise inflammatory bowel disease (IBD) treatment.

DESIGN

Retrospective cohort study of prospectively collected patient data.

SETTING

Tertiary IBD centre in London, UK.

PATIENTS

All patients at Guy's and St Thomas' Hospitals on anti-TNF who had levels measured between the start of testing in 2012 and October 2014.

INTERVENTIONS

Anti-TNF drug and anti-drug antibody levels as part of routine monitoring.

MAIN OUTCOME MEASURES

Indication for measuring levels and changes in management made as a result of the levels.

RESULTS

330 infliximab levels were carried out in 199 patients and 143 adalimumab levels were carried out in 103 patients. Levels were primarily done in those with evidence of loss of response; 37% of infliximab levels and 52% of adalimumab levels. Levels resulted in a change in management in 26% of patients in infliximab group and 25% of patients in adalimumab group; however, this was greater in those with loss of response, 62% and 61% respectively. Anti-drug antibodies were detected in 7% of patients.

CONCLUSIONS

Our early experience has demonstrated that measuring anti-TNF drug and anti-drug antibody levels can be useful in the optimisation of IBD management. In an increasing number of patients, particularly those with evidence of loss of response, it allows early decisions to be made regarding changing therapy. It also offers the potential for significant cost-saving by preventing pointless dose escalation in the context of therapeutic levels or when high-level anti-drug antibodies are present.

Prediction of Short- and Medium-term Efficacy of Biosimilar Infliximab Therapy. Do Trough Levels and Antidrug Antibody Levels or Clinical And Biochemical Markers Play the More Important Role?

BACKGROUND AND AIMS

Biosimilar infliximab CT-P13 received European Medicines Agency [EMA] approval in June 2013 for all indications of the originator product. In the present study, we aimed to evaluate the predictors of short- and medium-term clinical outcome in patients treated with the biosimilar infliximab at the participating inflammatory bowel disease [IBD] centres in Hungary.

METHODS

Demographic data were collected and a harmonised monitoring strategy was applied. Clinical and biochemical activities were evaluated at Weeks 14, 30, and 54. Trough level [TL] and anti-drug antibody [ADA] concentrations were measured by enzyme-linked immunosorbent assay [ELISA] [LT-005, Theradiag, France] at baseline at 14, 30 and 54 weeks and in two centres at Weeks 2 and 6.

RESULTS

A total of 291 consecutive IBD patients (184 Crohn's disease [CD] and 107 ulcerative colitis [UC]) were included. In UC, TLs at Week 2 predicted both clinical response and remission at Weeks 14 and 30 (clinical response/remission at Week 14: area under the curve [AUC] = 0.81, p < 0.001, cut-off: 11.5 μg/ml/AUC = 0.79, p < 0.001, cut-off: 15.3μg/ml; clinical response/remission at Week 30: AUC = 0.79, p = 0.002, cut-off: 11.5 μg/ml/AUC = 0.74, p = 0.006, cut-off: 14.5 μg/ml), whereas ADA positivity at Week 14 was inversely associated with clinical response at Week 30 [58.3% vs 84.8% ,p = 0.04]. Previous anti-tumour necrosis factor [TNF] exposure was inversely associated with short-term clinical remission [Week 2: 18.8% vs 47.8%, p = 0.03, at Week 6: 38.9% vs 69.7%, p = 0.013, at Week 14: 37.5% vs 2.5%, p = 0.06]. In CD, TLs at Week 2 predicted short-term [Week 14 response/remission, AUCTLweek2 = 0.715-0.721, p = 0.05/0.005] but not medium-term clinical efficacy. In addition, early ADA status by Week 14 [p = 0.04-0.05 for Weeks 14 and 30], early clinical response [p < 0.001 for Weeks 30/54] and normal C-reactive protein [CRP] at Week 14 [p = 0.005-0.0001] and previous anti-TNF exposure [p = 0.03-0.0001 for Weeks 14, 30, and 54] were associated with short-and medium-term clinical response and remission.

CONCLUSIONS

In UC, early TLs were predictive for short- and medium-term clinical efficacy, whereas in CD, Week 2 TLs were associated only with short-term clinical outcomes.

Pediatric Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including Crohn disease, ulcerative colitis, and IBD-unspecified, is a chronic immune-mediated condition of the gastrointestinal tract in which the goal of treatment is to induce and maintain durable remission. In pediatrics, there is a wide spectrum of presenting symptoms, but esophagogastroduodenoscopy and colonoscopy are imperative to confirming the diagnosis. Treatment goals include achieving mucosal healing of the gastrointestinal tract, reaching growth potential, limiting medication toxicities, and optimizing quality of life for all patients.

[Second Korean Guidelines for the Management of Crohn's Disease]

Crohn's disease (CD) is a chronic, progressive, and disabling inflammatory bowel disease (IBD) with an uncertain etiopathogenesis. CD can involve any site of the gastrointestinal tract from the mouth to the anus, and is associated with serious complications, such as bowel strictures, perforations, and fistula formation. The incidence and prevalence rates of CD in Korea are still lower compared with those in Western countries, but they have been rapidly increasing during the recent decades. Although there are no definitive curative modalities for CD, various medical and surgical therapies have been applied for the treatment of this disease. Concerning CD management, there have been substantial discrepancies among clinicians according to their personal experience and preference. To suggest recommendable approaches to the diverse problems of CD and to minimize the variations in treatment among physicians, guidelines for the management of CD were first published in 2012 by the IBD Study Group of the Korean Association for the Study of the Intestinal Diseases. These are the revised guidelines based on updated evidence, accumulated since 2012. These guidelines were developed by using mainly adaptation methods, and encompass induction and maintenance treatment of CD, treatment based on disease location, treatment of CD complications, including stricture and fistula, surgical treatment, and prevention of postoperative recurrence. These are the second Korean guidelines for the management of CD and will be continuously revised as new evidence is collected.

Combination therapy for inflammatory bowel disease

Biologic therapies such as infliximab and adalimumab have become mainstays of treatment for inflammatory bowel disease. Early studies suggested that combination therapy (CT) with infliximab and an immunomodulator drug such as azathioprine may help optimize biologic pharmacokinetics, minimize immunogenicity, and improve outcomes. The landmark SONIC trial in Crohn's disease and the UC SUCCESS trial in ulcerative colitis demonstrated CT with infliximab and azathioprine to be superior to monotherapy with either agent alone at inducing clinical remission in treatment naïve patients with moderate to severe disease. However, many unanswered questions linger. The role of CT in non-naive patients as well as the optimal duration of CT remains unknown. The effectiveness of CT with alternate biologics and/or alternate immunomodulators is not as clear, and it is unknown whether SONIC's conclusions can be extrapolated beyond infliximab and azathioprine. Also looming are the risks of CT including opportunistic infection and malignancy; specifically, lymphoma. This review lays out the evidence as it pertains to the risks and benefits of CT as well as the areas that require further research. With this information in hand, the practitioner may develop a treatment strategy that best suits each individual patient.

Proposal for an anti-TNF-exit strategy based on trough serum level

BACKGROUND AND AIMS

The aim of the study was to evaluate, if the strategy to stop anti-TNF treatment after determination of low trough serum levels and exclusion of inflammation is associated with lower relapse rates.

METHODS

Since 2013 we followed an exit strategy in patients treated with anti-TNF treatment for inflammatory bowel disease based on trough serum levels. The relapse rates were observed prospectively, data analysis was performed in a retrospective manner of the collected clinical data.

RESULTS

Forty patients were enrolled, who stopped anti-TNF therapy. 13 Patients followed the clinical algorithm, 27 patients were used as control group (13 patients with ulcerative colitis and 14 patients with Crohn's disease). 19 patients received Infliximab, 21 Adalimumab. The median follow-up time after discontinuation was 19 months (IQR 18). Relapses were observed in 22/40 patients (55%). Among the 13 patients with a targeted discontinuation of therapy based on the algorithm, three relapses were observed (23%), compared to 19/27 (70%) from the non-algorithm group (OR: 7.9; 95%-CI: 1.7-36.5). Relapse-free-survival after anti-TNF discontinuation was significantly higher in patients treated by the algorithm compared to the non-algorithm group (p = 0.032).

CONCLUSION

An exit strategy based on trough serum levels significantly reduces the relapse rate.

Therapeutic Drug Monitoring of Golimumab in the Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is a relapsing-remitting chronic inflammatory disorder affecting the mucosal surface in a continuous manner from the rectum through part of, or the entire, colon. Patients with severe disease and those who become refractory or intolerant to corticosteroids and/or immunosuppressants, require treatment with biologic agents that target tumor necrosis factor-α (TNF). Golimumab, a fully human monoclonal antibody, is the latest TNF antagonist to get approved for the treatment of moderate-to-severe UC. Subcutaneously administered golimumab induces and maintains clinical response, remission, and mucosal healing. Serum concentrations of golimumab are associated with response to therapy, as patients with higher drug exposure are more likely to achieve these outcomes. Since various patient and disease-related factors were shown to influence the pharmacokinetics of TNF antagonists, drug exposure may be variable over time and between patients, affecting success of therapy. A major contributing factor is immunogenicity, with development of anti-drug antibodies (ADAb) and an accelerated clearance of drug as a result. Although there is a growing body of evidence to support therapeutic drug monitoring (TDM) for infliximab and adalimumab, two other TNF antagonists, only limited data is available for golimumab. In addition, the clinically important drug exposure thresholds are not widely known, which has limited the use of TDM for golimumab in clinical practice. This review summarizes available data regarding the use of golimumab for UC, with emphasis on the pharmacokinetics, exposure-response relationship, and the role of TDM in optimizing therapy.

Intra-patient variability in adalimumab drug levels within and between cycles in Crohn's disease

BACKGROUND

Whether therapeutic drug monitoring for adalimumab needs to be performed at trough has not been defined.

AIM

To determine intra-patient adalimumab drug-level variation and to identify modulating patient and disease factors.

METHODS

In this prospective observational study, adult patients with Crohn's disease established on maintenance adalimumab had drug levels measured repeatedly according to pre-defined schedules (visit 1: day 4-6, visit 2: day 7-9, trough: day 13-14) across two consecutive fortnightly cycles. Disease activity was assessed using Harvey-Bradshaw Index, C-reactive protein and faecal calprotectin. For this analysis, trough levels ≥4.9 μg/mL were considered therapeutic.

RESULTS

Nineteen patients underwent 111 evaluations. Mean intra-patient drug levels from paired visits between cycles did not differ (visit1 cycle1: 4.81, cycle2: 5.21 μg/mL, P = 0.24, visit2 cycle1: 4.86, cycle2: 4.82, P = 0.91 and trough cycle1: 3.95, cycle2: 3.95, P = 0.99), irrespective of disease activity. Drug levels were stable over the first 9 days (visit 1-2), but declined to trough by a mean 1.06 and 0.89 μg/mL between visit 1 or 2, respectively (P < 0.001). Models using nontemporal factors (smoking, syringe delivery device) and levels at earlier visits accounted for 66-80% of the variance in trough levels. On receiver-operating curve analysis, thresholds identified in the first 9 days that predicted a therapeutic trough level were similar to the trough threshold itself, with high sensitivity but modest specificity.

CONCLUSION

While therapeutic drug monitoring should be performed at trough, a drug level ≥4.9 μg/mL obtained during the first 9 days predicts a therapeutic trough drug level with reasonable confidence.

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.

A Real-life Population Pharmacokinetic Study Reveals Factors Associated with Clearance and Immunogenicity of Infliximab in Inflammatory Bowel Disease

BACKGROUND

Several factors influencing the pharmacokinetics of infliximab (IFX) in inflammatory bowel disease (IBD) have been identified. We studied the impact of patient, disease, and treatment characteristics on clearance and immunogenicity of IFX in a real-world patient-with-IBD cohort.

METHODS

Serum concentrations of IFX and antibodies to IFX (ATIs) were measured in patients with IBD at a single center using an enzyme-linked immunosorbent assay and radioimmunoassay. Patient, disease, and treatment characteristics were retrospectively collected along with laboratory values. Pharmacokinetics and ATI titer were analyzed simultaneously by nonlinear mixed-effects modeling.

RESULTS

Nine hundred ninety-seven IFX concentrations and 756 ATI measurements from 332 patients with IBD (253 Crohn's disease and 79 ulcerative colitis) were included. Mean (SD) IFX dose was 5.47 ± 1.33 mg/kg. ATIs were detected in 75/332 (23%) patients; insufficient exposure below an IFX trough level of 3 μg/mL was the most predictive factor of developing ATI and resulted in a 4-fold increased risk of ATI development. ATI titer was a better predictor of IFX clearance than ATI as a dichotomous parameter. ATI titers >30 AU/mL were consistently associated with undetectable IFX concentrations. IFX clearance was affected by body weight (40-149 kg) ranging from 0.27 to 0.53 L/d, serum albumin (2-5.4 g/dL) from 0.93 to 0.24 L/d, and titers of ATIs (0-53,000 AU/mL) from 0.36 L/d to 15.93 L/d (P < 0.001). Previously biologic-treated patients exhibited a higher clearance of IFX.

CONCLUSIONS

IFX exposure below 3 μg/mL increases risk of ATIs. Identification of influential pharmacokinetics and ATI factors improves prediction of IFX levels, potentially allowing individualized dosing and cost reduction.

Higher infliximab trough levels are associated with perianal fistula healing in patients with Crohn's disease

BACKGROUND

Infliximab has been found to be efficacious in the treatment of fistulas in the setting of Crohn's disease, even though some patients do not benefit from therapy.

AIM

To assess the correlation between perianal fistula healing and trough levels of infliximab.

METHODS

In this cross-sectional study, we identified patients with Crohn's disease who had perianal fistulas and were treated with infliximab for at least 24 weeks. We excluded patients who underwent a faecal diversion procedure or proctectomy. Predictive variables included demographics, disease phenotype, disease activity, infliximab levels, anti-infliximab antibodies. The primary outcome was fistula healing defined as the absence of drainage. The secondary outcome was complete fistula closure and mucosal healing.

RESULTS

117 patients were included. Patients with fistula healing had significantly higher median serum infliximab levels when compared to those with active fistulas [15.8 vs. 4.4 μg/mL, respectively (P < 0.0001)]. There was an incremental gain in fistula healing with higher infliximab levels. The AUC for the association between fistula healing and infliximab levels was 0.82 (P < 0.0001), while the AUC for the association of infliximab levels and fistula closure was 0.69 (P = 0.014). Patients with anti-infliximab antibodies had a lower chance of achieving fistula healing (OR: 0.04 [95%CI: 0.005-0.3], P < 0.001).

CONCLUSIONS

There is a significant association between serum infliximab levels and rates of fistula healing. Achieving infliximab levels ≥10.1 mcg/mL in patients with Crohn's disease and perianal fistulas may improve outcomes as part of a treat-to-target strategy.

Adalimumab in ulcerative colitis - efficacy, safety and optimization in the era of treat-to target

INTRODUCTION

Active ulcerative colitis is associated with significant morbidity and impairment to quality of life. Adalimumab is a welcome addition to the therapeutic armamentarium for clinicians treating patients with moderate-severe ulcerative colitis refractory to conventional therapies, an indication with few prior treatment options. It offers the convenience of self-injection and is most appropriate for outpatients with moderate disease activity. Areas covered: This review briefly summarizes data from well-designed clinical trials and observational real-life studies that demonstrate the safety and efficacy of adalimumab in UC. Particular attention is paid to newer studies, including those with objective treatment endpoints and pharmacokinetic outcomes that incorporate a treat to target approach in inflammatory bowel disease. Expert opinion: Adalimumab is effective for the induction and maintenance of remission in patients with moderate-severe ulcerative colitis refractory to conventional therapies. At currently approved doses, it is most suitable for use in outpatients with moderate disease activity; higher doses may be required for patients with more severe disease. The convenience of self-injection will make it popular for remote patients and it may be an appropriate option in patients in whom monotherapy, rather than combination therapy with an immunomodulator, is preferred.