Thiopurines have no impact on outcomes of Crohn's disease patients beyond 12 months of maintenance treatment with infliximab

BACKGROUND

The emergence of new treatments the inflammatory bowel diseases (IBD) raised questions regarding the role of older agents, namely thiopurines.

AIMS

To clarify the benefits of combination treatment with thiopurines on Crohn's disease (CD) patients in the maintenance phase of infliximab.

METHODS

In this analysis of the 2-year prospective multicentric DIRECT study, patients were assessed in terms of clinical activity, faecal calprotectin (FC), C-reactive protein (CRP), and infliximab pharmacokinetics. A composite outcome based on clinical- and drug-related items was used to define treatment failure.

RESULTS

The study included 172 patients; of these, 35.5 % were treated with combination treatment. Overall, 18 % of patients achieved the composite outcome, without statistically significant differences between patients on monotherapy and on combination treatment (21.6% vs 11.5 %, p = 0.098). Median CRP, FC, and infliximab pharmacokinetic parameters were similar in both groups. However, in the sub-analysis by infliximab treatment duration, in patients treated for less than 12 months, the composite outcome was reached in fewer patients in the combination group than in the monotherapy group (7.1% vs 47.1 %, p = 0.021).

CONCLUSION

In CD patients in maintenance treatment with infliximab, combination treatment does not seem to have benefits over infliximab monotherapy beyond 12 months of treatment duration.

Validation of the Pharmacokinetic Model for Anti-TNFα Clearance in Infants Exposed to Anti-TNFα During Pregnancy

BACKGROUND AND AIMS

The ECCO guideline recommends postponing live attenuated vaccines in infants exposed to anti-tumour necrosis factor alpha [anti-TNFα] in utero until drug clearance. The aim was to validate the predictive performance of the anti-TNFα clearance model.

METHODS

Newborns and data for anti-TNFα concentrations from the prospective PETIT cohort were included. The anti-TNFα clearance model was used to predict all measured concentrations in the PETIT cohort, based on the measured cord blood concentration and the mean population clearance described in the model. Bayesian maximum a posteriori optimization was used to estimate the use of drug monitoring. Predictive capability and drug monitoring were assessed through mean absolute error [MAE], root mean squared prediction error, and limits of agreement according to Bland and Altman.

RESULTS

Observed drug concentrations after birth were within the 80% prediction interval in 94% of adalimumab samples and 93% of infliximab samples. The anti-TNFα clearance model accurately predicted the concentration at 6 months after birth with an MAE of 0.03 µg/mL [SD 0.03] for adalimumab and 0.11 µg/mL [SD 0.18] for infliximab based on cord blood concentrations. Addition of an additional sample between 1 and 4 months after birth improved the predictive accuracy for infliximab (MAE 0.05 [SD 0.09]) but not for adalimumab. Guidance for use in clinical practice was formulated.

CONCLUSIONS

The validity of the anti-TNFα clearance model is high, and hence can be used to guide clinicians regarding the timing of live vaccines in infants exposed to adalimumab or infliximab in utero.

Performance of Eight Infliximab Population Pharmacokinetic Models in a Cohort of Dutch Children with Inflammatory Bowel Disease

BACKGROUND AND OBJECTIVE

Efficacy of infliximab in children with inflammatory bowel disease can be enhanced when serum concentrations are measured and further dosing is adjusted to achieve and maintain a target concentration. Use of a population pharmacokinetic model may help to predict an individual's infliximab dose requirement. The aim of this study was to evaluate the predictive performance of available infliximab population pharmacokinetic models in an independent cohort of Dutch children with inflammatory bowel disease.

METHODS

In this retrospective study, we used data of 70 children with inflammatory bowel disease (443 infliximab concentrations) to evaluate eight models that focused on infliximab pharmacokinetic models in individuals with inflammatory bowel disease, preferably aged ≤ 18 years. Predictive performance was evaluated with prior predictions (based solely on patient-specific covariates) and posterior predictions (based on covariates and infliximab trough concentrations). Model accuracy and precision were calculated with relative bias and relative root mean square error and we determined the classification accuracy at the trough concentration target of ≥ 5 mg/L.

RESULTS

The population pharmacokinetic model by Fasanmade was identified to be most appropriate for the total dataset (relative bias before/after therapeutic drug monitoring: -20.7%/11.2% and relative root mean square error before/after therapeutic drug monitoring: 84.1%/51.6%), although differences between models were small and several were deemed suitable for clinical use. For the Fasanmade model, sensitivity and specificity for maximum posterior predictions for the next infliximab trough concentration to be ≥ 5 mg/L were respectively 83.5% and 80% with an area under the receiver operating characteristic curve of 0.870.

CONCLUSIONS

In our paediatric cohort, various models provided acceptable predictive performance, with the Fasanmade model deemed most suitable for clinical use. Model-informed precision dosing can therefore be expected to help to maintain infliximab trough concentrations in the target range.

Clinical Validation of a Capillary Blood Home-Based Self-Sampling Technique for Monitoring of Infliximab, Vedolizumab, and C-Reactive Protein Concentrations in Patients With Inflammatory Bowel Disease

BACKGROUND

Therapeutic drug monitoring provides important guidance for treatment of patients with inflammatory bowel disease (IBD) and could help to early identify treatment failure. This study aimed to validate a finger prick-based capillary blood sampling technique to measure biological trough levels and C-reactive protein (CRP) and evaluate patient performance and -support.

METHODS

In this prospective cohort study, patients with IBD receiving infliximab (IFX) or vedolizumab (VEDO) therapy performed finger prick-based capillary blood sampling at home. Additionally, blood was collected through routinely performed in-hospital venepuncture prior to biological infusion. IFX, VEDO, and CRP concentrations were measured by enzyme-linked immunosorbent assay. The concordance between methods was statistically evaluated and a survey was conducted to assess practicality and patient support.

RESULTS

In total, 81 patients (46 IFX, 35 VEDO) were enrolled. Mean differences between both methods were 0.42 (95% confidence interval, -1.74 to 2.58) μg/mL for IFX and 0.72 (95% confidence interval, -5.50 to 6.94) μg/mL for VEDO. Passing-Bablok regressions demonstrated no evidence for systematic or proportional biases. Venous and capillary IFX (ρ = 0.96, P < .001) and VEDO (ρ = 0.97, P < .001) levels strongly correlated and showed high intermethod agreement (Cohen's kappa: IFX = 0.82; VEDO = 0.94). Similarly, venous and capillary CRP levels were strongly correlated (ρ = 0.99, P < .001). Most patients (>95%) were able to successfully perform the self-sampling at home without prior instructions.

CONCLUSIONS

This study clinically validated a finger prick-based capillary blood self-sampling technique allowing concomitant home monitoring of biological levels and CRP for patients with IBD, who reported substantial support, tolerability, and practicality.

Assessing Immunogenicity of Biologic Drugs in Inflammatory Joint Diseases: Progress Towards Personalized Medicine

Biologic drugs have greatly improved treatment outcomes of inflammatory joint diseases, but a substantial proportion of patients either do not respond to treatment or lose response over time. Drug immunogenicity, manifested as the formation of anti-drug antibodies (ADAb), constitute a significant clinical problem. Anti-drug antibodies influence the pharmacokinetics of the drug, are associated with reduced clinical efficacy, and an increased risk of adverse events such as infusion reactions. The prevalence of ADAb differs among drugs and diseases, and the detection of ADAb also depends on the assay format. Most data exist for the tumor necrosis factor-alpha inhibitors infliximab and adalimumab, with a frequency of ADAb that ranges from 10 to 60% across studies. Measurement of ADAb and serum drug concentrations, therapeutic drug monitoring, has been suggested as a strategy to optimize therapy with biologic drugs. Although the recent randomized clinical Norwegian Drug Monitoring (NOR-DRUM) trials show promise towards a personalized medicine prescribing approach by therapeutic drug monitoring, several challenges remain. A plethora of assay formats, with widely differing properties, is currently used for measuring ADAb. Comparing results between different assays and laboratories is difficult, which complicates the development of cut-offs necessary for guidelines and the implementation of ADAb measurements in clinical practice. With the possible exception of infliximab, limited data on clinical relevance and cost effectiveness exist to support therapeutic drug monitoring as a routine clinical strategy to monitor biologic drugs in inflammatory joint diseases. The aim of this review is to provide an overview of the characteristics and prevalence of ADAb, predisposing factors to ADAb formation, commonly used assessment methods, clinical consequences of ADAb, and the potential implications of ADAb assessments for everyday treatment of inflammatory joint diseases.

Predictors of Immunogenicity to Infliximab among Patients with Inflammatory Bowel Disease: Does Ethnicity Matter?

BACKGROUND

Up to 60% of inflammatory bowel disease (IBD) patients treated with infliximab develop antibodies to infliximab (ATI), which are associated with low drug levels and loss of response (LOR). Hence, mapping out predictors of immunogenicity toward infliximab is essential for tailoring patient-specific therapy. Jewish Sephardi ethnicity, in addition to monotherapy, has been previously identified as a potential risk factor for ATI formation and infliximab failure.

OBJECTIVES

To explore the association between Jewish sub-group ethnicity among patients with IBD and the risk of infliximab immunogenicity and therapy failure. To confirm findings of a previous cohort that addressed the same question.

METHODS

This retrospective cohort study included all infliximab-treated patients of Jewish ethnicity with regular prospective measurements of infliximab trough levels and ATI. Drug and ATI levels were prospectively measured, clinical data was retrieved from medical charts.

RESULTS

The study comprised 109 Jewish patients (54 Ashkenazi, 55 Sephardi) treated with infliximab. There was no statistically significant difference in proportion of ATI between Sephardi and Ashkenazi patients with IBD (32% Ashkenazi and 33% Sephardi patients developed ATI, odds ratio [OR] 0.944, P = 0.9). Of all variables explored, monotherapy and older age were the only factors associated with ATI formation (OR 0.336, 95% confidence interval 0.145-0.778, P = 0.01, median 34 vs. 28, interquartile range 28-48, 23-35 years, P = 0.02, respectively).

CONCLUSIONS

Contrary to previous findings, Sephardi Jewish ethnicity was not identified as a risk factor for ATI formation compared with Ashkenazi Jewish ethnicity. Other risk factors remained unchanged.

Comparison of SB2-Infliximab With Originator-Infliximab in the Measurement of Serum Concentrations: A Short Communication

BACKGROUND

The optimal use of infliximab depends on the measurement of trough levels with subsequent appropriate dose adjustment. With the introduction of biosimilars, it is important to demonstrate that the biosimilar behaves similarly in the assay used as the originator-infliximab, for which the assays were developed. In this study, the authors aimed to compare the concentrations of SB2-infliximab (Renflexis) with that of originator-infliximab (Remicade) when added to serum from healthy subjects and those with inflammatory bowel disease when measured by commonly used commercial assays.

METHODS

Sera from 2 healthy controls, 2 patients with ulcerative colitis (1 with quiescent disease and 1 with active disease), and 2 patients with Crohn disease (1 with quiescent disease and 1 with active disease) were spiked with SB2-infliximab or originator-infliximab at 0-20 mcg/mL. Concentrations were measured using 3 commonly used assay kits (Lisa-Tracker, Shikari Q-Inflix, Promonitor IFX) and one rapid test (Quantum Blue). The results were compared using Bland-Altman techniques.

RESULTS

Close agreement was observed between measured concentrations for all assays, irrespective of the origin of the serum. Limits of agreement varied between at worst -0.302 and 0.465 mcg/mL, with the mean difference between the molecules being at worst 0.04 mcg/mL (95% confidence intervals, -0.011 to 0.093).

CONCLUSIONS

The originator and SB-2 biosimilar-infliximab behaved similarly in several currently used assays in their concentrations in biological fluids. Clinicians can be confident that therapeutic drug monitoring using platforms designed and developed for the originator-infliximab can be applied to SB-2-infliximab.

Association of IgG1 Antibody Clearance with FcγRIIA Polymorphism and Platelet Count in Infliximab-Treated Patients

The FcγRIIA/CD32A is mainly expressed on platelets, myeloid and several endothelial cells. Its affinity is considered insufficient for allowing significant binding of monomeric IgG, while its H131R polymorphism (histidine > arginine at position 131) influences affinity for multimeric IgG2. Platelet FcγRIIA has been reported to contribute to IgG-containing immune-complexe clearance. Given our finding that platelet FcγRIIA actually binds monomeric IgG, we investigated the role of platelets and FcγRIIA in IgG antibody elimination. We used pharmacokinetics analysis of infliximab (IgG1) in individuals with controlled Crohn’s disease. The influence of platelet count and FcγRIIA polymorphism was quantified by multivariate linear modelling. The infliximab half-life increased with R allele number (13.2, 14.4 and 15.6 days for HH, HR and RR patients, respectively). It decreased with increasing platelet count in R carriers: from ≈20 days (RR) and ≈17 days (HR) at 150 × 10⁹/L, respectively, to ≈13 days (both HR and RR) at 350 × 10⁹/L. Moreover, a flow cytometry assay showed that infliximab and monomeric IgG1 bound efficiently to platelet FcγRIIA H and R allotypes, whereas panitumumab and IgG2 bound poorly to the latter. We propose that infliximab (and presumably any IgG1 antibody) elimination is partly due to an unappreciated mechanism dependent on binding to platelet FcγRIIA, which is probably tuned by its affinity for IgG2.

The effect of early trough level of infliximab on subsequent disease course in patients with Crohn disease: A prospective cohort study

Decreased trough level of infliximab (TLI) is associated with diminished efficacy in patients with Crohn disease (CD). We examined whether TLI at 14 weeks subsequent to the start of infliximab (IFX) treatment would impact long-term clinical course.Serum IFX levels and antibodies to IFX (ATI) at 14 and 54 weeks after IFX administration were measured in 12 patients with mild to moderate CD. We examined patient background, clinical severity, blood test values, and the relationship between ATI and TLI up to 108 weeks.We compared the group with TLI < 3 μg/mL at 14 weeks (TLI(14) < 3 group) the group with TLI > 3 μg/mL (TLI(14) ≥ 3 group). Patients in the TLI(14) ≥ 3 group were significantly more likely to use immunomodulators before IFX treatment induction (P = .01). At 54 weeks, 2 cases of ATI production were observed in the TLI(14) < 3 group, but no ATI production was observed in the TLI(14) ≥ 3 group. TLI in the TLI(14) ≥ 3 group at 54 weeks was significantly higher than in the TLI(14) < 3 group (6.5 μg/mL vs 1.0 μg/mL; P < .01). Although CD activity index and serum albumin values in the TLI(14) ≥ 3 group at 14, 54, and 108 weeks significantly improved compared to baseline, these improvements were not observed in the TLI(14) < 3 group. The remission maintenance rate at 108 weeks evaluated with the Kaplan-Meier method was significantly higher in the TLI(14) ≥ 3 group than the TLI(14) < 3 group (100% vs 33.3%; P = .02).The TLI 14 weeks after IFX treatment in patients with CD affects long-term outcome.

Clinical Pharmacokinetics and Pharmacodynamics of Infliximab in the Treatment of Inflammatory Bowel Disease

Infliximab was the first monoclonal antibody to be approved for the treatment of pediatric and adult patients with moderately to severely active Crohn's disease (CD) and ulcerative colitis (UC). It has been shown to induce and maintain both clinical remission and mucosal healing in pediatric and adult patients with inflammatory bowel disease (IBD) who are unresponsive or refractory to conventional therapies. The administration of infliximab is weight-based and the drug is administered intravenously. The volume of distribution of infliximab is low and at steady state ranges from 4.5 to 6 L. Therapeutic monoclonal antibodies, such as immunoglobulins, are cleared from the circulation primarily by catabolism. Median infliximab half-life is approximately 14 days. Infliximab concentration-time data in patients with CD and UC have been shown to be highly variable within an individual patient over time and between individuals by multiple population pharmacokinetic models. Covariates that have been identified to account for a part of the observed inter- and intra-individual variability in clearance are the presence of antidrug antibodies, use of concomitant immunomodulators, degree of systemic inflammation, serum albumin concentration, and body weight, which can affect the pharmacodynamic response. This article provides a comprehensive review of the clinical pharmacokinetics and pharmacodynamics of infliximab, as well as the role of therapeutic drug monitoring in the treatment of IBD.

Combination Therapy With Infliximab and Azathioprine Improves Infliximab Pharmacokinetic Features and Efficacy: A Post Hoc Analysis

BACKGROUND & AIMS

Among immunosuppressive- and biologic-naïve patients with moderately-to-severely active Crohn's disease (CD), a higher proportion of those treated with the combination of infliximab and azathioprine achieved corticosteroid-free remission at week 26 (CSFR26) than those given infliximab monotherapy; patients given the combination therapy also had higher serum concentrations of infliximab. Enhanced benefit of combination therapy may occur through synergistic modes of action or the influence of azathioprine on infliximab pharmacokinetics.

METHODS

We analyzed data from 206 patients from whom week 30 serum samples were available: 97 received infliximab monotherapy (5 mg/kg, n = 97) and 109 received combination therapy (2.5 mg/kg/day; n = 109). Proportions of patients achieving CSFR26 and mucosal healing (absence of ulcers) at week 26 were calculated for each quartile of serum concentrations of infliximab, and exposure-response relationships were compared.

RESULTS

Within quartiles of serum concentrations of infliximab, CSFR26 did not differ significantly between patients who received combination therapy vs monotherapy. However, among patients in the lowest quartile of serum concentration of infliximab, twice as many patients who received infliximab monotherapy achieved CSFR26 vs combination therapy. Anti-drug antibodies were detected only in the lowest quartile of serum concentrations of infliximab-in 35.9% of patients given monotherapy and 8.3% of patients given combination therapy.

CONCLUSION

Among patients with CD and similar serum concentrations of infliximab, combination therapy with azathioprine was not significantly more effective than infliximab monotherapy. Combination therapy with azathioprine appears to improve efficacy by increasing pharmacokinetic features of infliximab. ClinicalTrials.gov, NCT00094458.

Dried blood samples can support monitoring of infliximab concentrations in patients with inflammatory bowel disease: A clinical validation

Aims

Therapeutic drug monitoring (TDM) can optimize the efficacy of infliximab (IFX) in patients with inflammatory bowel disease (IBD). Because of the delay between blood samples taken at trough and availability of results, dose adjustments can only be carried out at the next infusion, typically 8 weeks later. Dried blood samples (DBS) performed at home to measure IFX concentrations can reduce the time to adapt dose/dosing interval. Here, we aimed to validate the clinical application of DBS for IFX in IBD patients and to evaluate the feasibility of home sampling.

Methods

DBS results from 40 IBD patients on IFX treatment were compared to serum sample results at trough, peak, and 3–5 weeks after IFX infusion. Subsequently, patients performed DBS home sampling one week before the next IFX infusion. These were compared to serum concentrations as predicted by Bayesian analysis.

Results

IFX concentrations from finger prick and venous puncture correlate well. DBS IFX concentrations showed high correlation with serum IFX concentrations (Spearman correlation: ≥0.965), without bias. Passing‐Bablok regression for IFX concentrations in DBS from home sampling also showed no bias (intercept: 1.02 mg L⁻¹ (95% CI −1.77–2.04 mg L⁻¹), slope: 0.82 (95% CI 0.63–1.40)), with reasonable correlation (Spearman correlation: 0.671).

Conclusions

Timely adjustment of IFX dose/dosing interval can be facilitated by IFX concentration measurement in home‐sampled DBS. DBS is a reliable method to measure IFX and can be used to predict IFX trough concentrations.

A Narrative Review on Anti-Tumor Necrosis Factor α Therapies in Inflammatory Bowel Disease During Pregnancy: Immunoglobulin Placental Translocation and its Impact

INTRODUCTION

Inflammatory bowel disease activity is associated with adverse pregnancy outcomes. Anti-tumor necrosis factor α therapy is often required to treat flares and to maintain disease remission. However, there are concerns regarding treatment with these agents during pregnancy, as they actively cross the placental barrier.

MATERIAL AND METHODS

Studies regarding anti-tumor necrosis factor α therapy during pregnancy were identified from PubMed from 1958 to January 2018. The reference lists of the selected studies were reviewed to identify complementary publications.

RESULTS AND DISCUSSION

Anti-tumor necrosis factor α agents are efficient treatments for moderate-to-severe inflammatory bowel disease and may ensure remission during pregnancy. Although these drugs cross the placenta, they are considered safe for both the mother and the fetus. Furthermore, up-to-date guidelines support therapy continuation during pregnancy aiming for disease control. The same guidelines also consider stopping treatment during the third trimester to limit maternal-fetal drug transfer. However, data shows that this strategy does not completely prevent fetus exposure. In addition, stopping treatment incurs in risk of disease flare and threatens subsequent therapy response. Fetus drug exposure has not showed an association with adverse childhood development. However, as infant drug levels could be detected up to seven months after birth, postponement of live virus vaccination is recommended.

CONCLUSION

There should be no disagreement among the medical community as to the need to maintain therapy aiming for disease remission during gestation in inflammatory bowel disease. Anti-tumor necrosis factor α agents are safe for both the mother and the fetus.

Analysis of Tryptic Peptides from Therapeutic Monoclonal Antibodies Using LC-MS/MS

Immunotherapies are a hot topic, with the potential to impact our understanding of the immune system and treat a diverse array of conditions. Therapeutic monoclonal antibodies (mAbs) are part of this revolution, and clinical chemists are aware of the success of the biologic drugs. Antibodies are not just immunoassay reagents anymore but are also present in clinical serum samples from more and more patients each day. The clinical laboratory will have many roles as mAb therapies expand, including the development of new assays to differentiate a mAb from an endogenous, disease-causing clone and monitoring therapeutic drugs for better patient outcomes and assessing for the loss of response to therapy.Therapeutic mAbs use has expanded significantly in the last 5 years, and depending on their target or their concentration, they may impact routine clinical testing for patients. Optimizing therapy during the induction phase to keep the mAb concentrations above certain thresholds has proven to be associated with improved responses and better outcomes in chronic conditions such as inflammatory bowel disease. This chapter will describe a LC-MS/MS protocol for analysis of tryptic peptides unique to infliximab (clonotypic peptides) for quantitation of the mAb. The protocol can be adapted to other mAbs with similar outcomes and is a useful, relatively simple strategy for measurement of mAbs.

Severe endoscopic lesions are not associated with more infliximab fecal loss in acute severe ulcerative colitis

BACKGROUND

It has been observed that early infliximab (IFX) fecal excretion in patients with acute severe ulcerative colitis (ASUC) was associated with low treatment response.

AIM

The objective was to assess if severe endoscopic lesions (SEL) were associated with IFX loss in the stool as well as low IFX concentrations in plasma at day 1 and 2 in a cohort of patients admitted for ASUC.

METHODS

Consecutive patients admitted for a steroid-refractory ASUC requiring IFX and who underwent flexible sigmoidoscopy before starting the drug were included in a case-control, prospective, two-center study. Cases were patients with SEL and controls those without SEL. Plasmatic and fecal IFX concentrations were measured at day 1 and 2.

RESULTS

Among the 15 patients analyzed (10 men; median age: 49 years), 6 were cases harboring SEL at baseline. IFX was detected in the stool in 2/6 (33%) of cases and 4/9 (44%) of controls (p = 1) and no difference was observed between the two groups regarding plasmatic concentrations at day 1 or 2 (p = 1).

CONCLUSION

In ASUC, SEL were not associated with more loss of IFX in the stool or lower plasmatic levels. Early IFX pharmacokinetics in this setting does not seem related to endoscopic severity.

Infliximab for pediatric patients with Crohn's disease: A Phase 3, open-label, uncontrolled, multicenter trial in Japan

Objectives

The prevalence of pediatric Crohn’s disease (CD) is increasing in Japan and other countries, and many patients are unresponsive to or do not tolerate current treatment options. This study aimed to investigate the efficacy, safety, and pharmacokinetic profile of infliximab (IFX) in pediatric patients with moderate-to-severe CD and inadequate response to existing treatment.

Study design

This was an open-label, uncontrolled, multicenter Phase 3 study conducted at nine sites in Japan between April 2012 and March 2015. Pediatric patients (aged 6–17 years) with moderate-to-severe CD were treated with IFX 5 mg/kg at Weeks 0, 2, and 6, and at 8-week intervals thereafter until Week 46, with final evaluation at Week 54. IFX dose was increased to 10 mg/kg in patients who showed loss of response to IFX from Week 14 onwards.

Results

A total of 14 patients fulfilled eligibility criteria and were treated. Dose-escalation criteria were met by five patients who then received 10 mg/kg IFX. The remaining nine patients continued to receive an IFX dose of 5 mg/kg. IFX rapidly improved clinical symptoms and its effect was maintained for up to 54 weeks. Overall Pediatric Crohn’s Disease Activity Index (PCDAI) response rate was 85.7%, and overall PCDAI remission rate was 64.3%. Three out of five patients who increased IFX dose regained PCDAI remission by retrieval of serum IFX concentration. Adverse events and serious adverse events occurred in 100.0% and 14.3% of patients, respectively. There was no substantial difference in the safety profiles of patients taking a constant dose of 5 mg/kg and those taking an increased dose of 10 mg/kg.

Conclusions

These findings support the effective use of IFX in the treatment of pediatric patients with CD where other treatments have proven ineffective.

The New Test for Monitoring Infliximab Therapy: From Laboratory to Clinical Practice

BACKGROUND

Biological agents for anti-tumor necrosis factor-α therapy have revolutionized treatments for autoimmune diseases; however, approximately 20% of rheumatology and 40% of gastroenterology patients do not respond to the therapy, or they show reduced drug efficacy because of anti-drug antibody (ADA) formation.

OBJECTIVES

To evaluate laboratory tools for individual monitoring of infliximab therapy and the relationship between ADA and infliximab serum levels, ADA and clinical response, and ADA and autoantibodies.

METHODS

Our study comprised patients treated with infliximab and affected by selected rheumatology and gastroenterology diseases. Sera were analyzed for infliximab, total-anti-drug antibodies (Total-ADA), and free-anti-drug antibodies (Free-ADA) serum levels and for the detection of specific autoantibodies.

RESULTS

We analyzed 73 patients. Total-ADA were detected in 26 rheumatology and 21 gastroenterology patients. Serum infliximab levels were significantly lower in Total-ADA positive patients (P = 0.01 for rheumatology group, P = 0.02 for gastroenterology group). A lack of response was observed in 7 rheumatology and 15 gastroenterology samples. Total-ADA serum levels were statistically significantly higher in patients with treatment failure in both groups (P = 0.01 and P = 0.001, respectively). There was no significant association between the presence of Total-ADA and other autoantibodies. Free-ADA were detected in only 27 rheumatology patients. Results showed a significant correlation with clinical outcome (P = 0.006).

CONCLUSIONS

The correlation with clinical response suggests that the presence of ADA could interfere with efficacy of therapy. The tests for monitoring therapy may be an important tool to assist clinicians in early detection and prevention of therapy failure.

Calprotectin and the Magnitude of Antibodies to Infliximab in Clinically-stable Ulcerative Colitis Patients are More Relevant Than Infliximab Trough Levels and Pharmacokinetics for Therapeutic Escalation

Although infliximab (IFX) is an efficient therapy for ulcerative colitis (UC) patients, a considerably high rate of therapeutic failures still occurs. This study aimed at a better understanding of IFX pharmacokinetics and pharmacodynamics among clinically-asymptomatic UC patients. This was a multicentric and prospective study involving 65 UC patients in the maintenance phase of IFX therapy. There were no significant differences between patients with positive and negative clinical, endoscopic and histological outcomes concerning their IFX trough levels (TLs), area under the IFX concentration vs. time curve (AUC), clearance and antibodies to infliximab (ATI) levels. However, the need to undergo therapeutic escalation later in disease development was significantly associated with higher ATI levels (2.62μg/mL vs. 1.15μg/mL, p=0.028). Moreover, and after adjusting for disease severity, the HR (hazard ratio) for therapeutic escalation was significantly decreased for patients with an ATI concentration below 3μg/mL (HR=0.119, p=0.010), and increased for patients with fecal calprotectin (FC) level above 250μg/g (HR=9.309, p=0.018). In clinically-stable UC patients, IFX pharmacokinetic features cannot predict therapeutic response on a short-term basis. However, high levels of ATIs or FC may be indicative of a future therapeutic escalation.

Extensive preclinical evaluation of an infliximab biosimilar candidate

Infliximab is therapeutic monoclonal antibody (mAb) against TNF-α employed in the treatment of immunoinflammatory diseases. The development of biosimilar mAbs is a global strategy to increase drug accessibility and reduce therapy-associated costs. Herein we compared key physicochemical characteristics and biological activities produced by infliximab and infliximab-Probiomed in order to identify functionally relevant differences between the mAbs. Binding of infliximab-Probiomed to TNF-α was specific and had kinetics comparable to that of the reference product. Both mAbs had highly similar neutralizing efficacy in HUVEC cell cultures stimulated with TNF-α. In vitro induction of CDC and ADCC were also similar between the evaluated products. In vivo comparability was assessed using a transgenic mouse model of arthritis that expresses human TNF-α in a 13-week multiple-administration study. Infliximab and infliximab-Probiomed showed comparable efficacy, safety, and pharmacokinetic profiles. Our results indicate that infliximab-Probiomed has highly similar activities to infliximab in preclinical models, warranting a clinical evaluation of its biosimilarity.

A randomised, double-blind, phase III study comparing SB2, an infliximab biosimilar, to the infliximab reference product Remicade in patients with moderate to severe rheumatoid arthritis despite methotrexate therapy

OBJECTIVES

To compare the efficacy, safety, immunogenicity and pharmacokinetics (PK) of SB2 to the infliximab reference product (INF) in patients with moderate to severe rheumatoid arthritis (RA) despite methotrexate therapy.

METHODS

This is a phase III, randomised, double-blind, multinational, multicentre parallel group study. Patients with moderate to severe RA despite methotrexate therapy were randomised in a 1:1 ratio to receive either SB2 or INF of 3 mg/kg. The primary end point was the American College of Rheumatology 20% (ACR20) response at week 30. Inclusion of the 95% CI of the ACR20 response difference within a ±15% margin was required for equivalence.

RESULTS

584 subjects were randomised into SB2 (N=291; 290 analysed) or INF (N=293). The ACR20 response at week 30 in the per-protocol set was 64.1% in SB2 versus 66.0% in INF. The adjusted rate difference was -1.88% (95% CI -10.26% to 6.51%), which was within the predefined equivalence margin. Other efficacy outcomes such as ACR50/70, disease activity score measured by 28 joints and European League against Rheumatism response were similar between SB2 and INF. The incidence of treatment-emergent adverse events was comparable (57.6% in SB2 vs 58.0% in INF) as well as the incidence of antidrug antibodies (ADA) to infliximab up to week 30 (55.1% in SB2 vs 49.7% in INF). The PK profile was similar between SB2 and INF. Efficacy, safety and PK by ADA subgroup were comparable between SB2 and INF.

CONCLUSIONS

SB2 was equivalent to INF in terms of ACR20 response at week 30. SB2 was well tolerated with a comparable safety profile, immunogenicity and PK to INF.

TRIAL REGISTRATION NUMBER

NCT01936181.

Personalized therapy with TNF-inhibitors in Crohn's disease: optimizing treatment outcomes by monitoring drug levels and anti-drug antibodies

Therapeutic monoclonal antibodies (Abs) targeting the proinflammatory cytokine, TNF-α have revolutionized the treatment of inflammatory bowel disease (IBD), and raised treatment goals from symptom control to maintenance of clinical remission with mucosal healing. However, clinicians are challenged by a significant proportion of patients not responding to TNF-inhibitors or losing effect over time, and by the high costs of these drugs along with their potential side effects. The aim of this dissertation was therefore to examine if anti-TNF treatment outcomes can be improved by tailoring therapy on an individual patient basis by considering relevant prognostic variables. The main finding is that personalized treatment with TNF-inhibitors by use of an algorithm defined by measurements of anti-TNF drug and anti-drug Abs to guide interventions at therapeutic failure can be useful to secure optimal clinical, economic, and patient reported outcomes. Furthermore, the present studies have documented the key role of measurements of anti-TNF drug and anti-drug Abs to elucidate conditions related to pharmacokinetics and pharmacodynamics of these agents in individual patients, and to serve as prognostic markers of anti-TNF treatment outcomes. In addition, knowledge has been provided on how to interpret and integrate measurements of anti-TNF drug and anti-drug Abs in the clinical management of individual IBD patients taking into account potential pit-falls and biases. Hence, the studies forming the basis for this dissertation have yielded novel insights into the technical, temporal, and methodological complexities and challenges related to application of personalized anti-TNF treatment strategies based on measurements of anti-TNF drug and anti-drug Abs, and established measures to proactively address and accommodate these - both technically and clinically. Although not yet completely resolved, this dissertation has also laid a foundation for individually tailored anti-TNF therapy by use of algorithms based on measurements of anti-TNF drug and anti-drug Abs involving different clinical scenarios than treatment failure, for example in the context of drug withdrawal among selected subgroups in remission. Finally, this dissertation has demonstrated that personalized anti-TNF therapy cannot at this time be done on the basis of prognostic variables related to specific characteristics of individual patients, their disease and the anti-TNF treatment regimen, but that management decisions integrating knowledge of these factors can aid improving the overall benefit-risk ratio of anti-TNF treatment outcomes in individual patients. In conclusion, this dissertation has brought personalized anti-TNF therapy in IBD from bench to bedside.

Infliximab therapy for intestinal, neurological, and vascular involvement in Behcet disease: Efficacy, safety, and pharmacokinetics in a multicenter, prospective, open-label, single-arm phase 3 study

Behçet disease (BD) is a multisystem disease associated with a poor prognosis in cases of gastrointestinal, neurological, or vascular involvement. We conducted a multicenter, prospective, open-label, single-arm phase 3 study to determine the efficacy, safety, and pharmacokinetics of infliximab (IFX) in BD patients with these serious complications who had displayed poor response or intolerance to conventional therapy.IFX at 5 mg/kg was administered to 18 patients (11 intestinal BD, 3 neurological BD [NBD], and 4 vascular BD [VBD]) at weeks 0, 2, and 6 and every 8 weeks thereafter until week 46. In patients who showed inadequate responses to IFX after week 30, the dose was increased to 10 mg/kg. We then calculated the percentage of complete responders according to the predefined criteria depending on the symptoms and results of examinations (ileocolonoscopy, brain magnetic resonance imaging, computed tomography angiography, positron emission tomography, cerebrospinal fluid, or serum inflammatory markers), exploring the percentage of complete responders at week 30 (primary endpoint).The percentage of complete responders was 61% (11/18) at both weeks 14 and 30 and remained the same until week 54. Intestinal BD patients showed improvement in clinical symptoms along with decrease in C-reactive protein (CRP) levels after week 2. Consistently, scarring or healing of the principal ulcers was found in more than 80% of these patients after week 14. NBD patients showed improvement in clinical symptoms, imaging findings, and cerebrospinal fluid examinations. VBD patients showed improvement in clinical symptoms after week 2 with reductions in CRP levels and erythrocyte sedimentation rate. Imaging findings showed reversal of inflammatory changes in 3 of the 4 VBD patients. Irrespective of the type of BD, all patients achieved improvement in quality of life, leading to the dose reduction or withdrawal of steroids. IFX dose was increased to 10 mg/kg in 3 intestinal BD patients, resulting in the improvement of clinical symptoms, CRP levels, and visual analogue scale score. Safety and pharmacokinetics profiles were comparable to those in patients with rheumatoid arthritis or Crohn disease. These findings support IFX as a new therapeutic option for patients with intestinal BD, NBD, or VBD.

Practical Use of Infliximab Concentration Monitoring in Pediatric Crohn Disease

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Systematic Review and Meta-Analysis: Serum Infliximab Levels During Maintenance Therapy and Outcomes in Inflammatory Bowel Disease

BACKGROUND AND AIMS

A number of observational studies have reported an association between serum levels of infliximab [IFX] at various thresholds, and clinical outcomes in inflammatory bowel disease [IBD]. This association has not previously been systematically analysed.

METHODS

Systematic review of studies that reported serum infliximab levels according to outcomes in IBD. Primary outcome was clinical remission, and secondary outcomes included endoscopic remission, C-reactive protein [CRP] levels, and colectomy. Meta-analysis of raw data was performed where appropriate. A quality assessment was also undertaken.

RESULTS

A total of 22 studies met the inclusion criteria, including 3483 patients; 12 studies reported IFX levels in a manner suitable for determining effect estimates. During maintenance therapy, patients in clinical remission had significantly higher mean trough IFX levels than patients not in remission: 3.1 µg/ml versus 0.9 µg/ml. The standardised mean difference in serum IFX levels between groups was 0.6 µg/ml (95% confidence interval [CI] 0.4-0.9, p = 0.0002]. Patients with an IFX level > 2 µg/ml were more likely to be in clinical remission (risk ratio [RR] 2.9, 95% CI 1.8-4.7, p < 0.001], or achieve endoscopic remission [RR 3, 95% CI 1.4-6.5, p = 0.004] than patients with levels < 2 µg/ml.

CONCLUSIONS

There is a significant difference between serum infliximab levels in patients with IBD in remission, compared with those who relapse. A trough threshold during maintenance > 2 µg/ml is associated with a greater probability of clinical remission and mucosal healing.

Infliximab Concentration Thresholds During Induction Therapy Are Associated With Short-term Mucosal Healing in Patients With Ulcerative Colitis

BACKGROUND & AIMS

Mucosal healing is an independent predictor of sustained clinical remission in patients with ulcerative colitis (UC) treated with infliximab. We investigated whether infliximab concentrations during induction therapy are associated with short-term mucosal healing (STMH) in patients with UC.

METHODS

We performed a retrospective, single-center analysis of data collected from a tertiary referral center from 101 patients with UC who received scheduled induction therapy with infliximab at weeks 0, 2, and 6 and had an endoscopic evaluation at baseline and after induction therapy. STMH was defined as Mayo endoscopic sub-score ≤1, assessed at weeks 10-14, with baseline sub-score ≥2. Infliximab concentrations were evaluated in serum samples collected at weeks 0, 2, 6, and 14 of infliximab therapy by using an enzyme-linked immunosorbent assay we developed.

RESULTS

Fifty-four patients (53.4%) achieved STMH. Patients with STMH had a higher median infliximab concentration at weeks 2, 6, and 14 than patients without STMH. A receiver operating characteristic (ROC) analysis identified infliximab concentration thresholds of 28.3 (area under the ROC curve [AUROC], 0.638), 15 (AUROC, 0.688), and 2.1 μg/mL (AUROC, 0.781) that associated with STMH at weeks 2, 6, and 14, respectively. Multiple logistic regression analysis identified infliximab concentration ≥15 at week 6 (P = .025; odds ratio, 4.6; 95% confidence interval, 1.2-17.1) and ≥2.1 μg/mL at week 14 (P = .004; odds ratio, 5.6; 95% confidence interval, 1.7-18) as independent factors associated with STMH.

CONCLUSIONS

In an analysis of data from real-life clinical practice, we associated infliximab concentrations during the induction therapy with STMH in patients with UC.

Pharmacokinetic Features and Presence of Antidrug Antibodies Associate With Response to Infliximab Induction Therapy in Patients With Moderate to Severe Ulcerative Colitis

BACKGROUND & AIMS

The pharmacokinetics of infliximab during induction treatment for ulcerative colitis (UC) have not been studied. We investigated serum concentrations of infliximab and the early appearance of antibodies to infliximab (ATI) during induction treatment in patients with moderate-to-severe UC.

METHODS

We performed a prospective analysis of 19 consecutive patients with moderate-severe UC (endoscopic Mayo ≥ 2) receiving induction therapy with infliximab (5 mg/kg at weeks 0, 2, and 6) at 2 centers in Amsterdam, The Netherlands, from July 2012 through March 2014. Serial serum and fecal samples were collected for 6 weeks and concentrations of infliximab, ATI, c-reactive protein (CRP), albumin, and fecal calprotectin were measured. Treatment success was defined as endoscopic response (≥ 1 point reduction in the endoscopic Mayo score) at week 8.

RESULTS

Eleven patients (58%) had an endoscopic response. The median serum concentrations of infliximab at week 6 were 8.1 μg/mL in responders (interquartile range, 3.0-13.7 μg/mL) and 2.9 μg/mL in nonresponders (interquartile range, 0.01-5.8 μg/mL) (P = .03). ATIs were detected in 7 patients as early as day 18 (median, 28 d; interquartile range, 18-42 d). Six of the 8 nonresponders tested positive for ATIs vs 1 of 11 responders (P < .01; odds ratio, 30.0; 95% CI, 2.2-406.2). Patients with a baseline concentration of CRP greater than 50 mg/L had lower drug exposure from weeks 0 to 6 (587 mg/L/d in patients with high levels of CRP vs 1361 mg/L/day in patients with low CRP; P = .001). The median area under the curve for serum concentration of infliximab during induction therapy was 1230 mg/L/d in nonresponders vs 1352 mg/L/d in responders (P = .65).

CONCLUSIONS

There is a significant difference in serum concentration of infliximab at week 6 of treatment between responders and nonresponders. Early development of ATIs during induction therapy reduces the serum concentration of infliximab and is associated with nonresponse to treatment. Patients with high baseline serum levels of CRP had lower serum concentrations of infliximab.

CLINICAL TRIAL NUMBER

NL39626.018.12.

Low Dose Infliximab for Prevention of Postoperative Recurrence of Crohn's Disease: Long Term Follow-Up and Impact of Infliximab Trough Levels and Antibodies to Infliximab

Objective

In patients with postoperative recurrence of Crohn’s disease endoscopic and clinical remission can be maintained for up to 1 year with low infliximab doses (3 mg/Kg). However, in theory low-dose infliximab treated patients could develop subtherapeutic trough levels, infiximab antibodies, and might loose response to therapy. To verify this hypothesis infliximab pharmacokinetics and clinical/endoscopic response were checked in a group of patients treated in the long term with low infliximab doses.

Design

Infliximab antibodies, infliximab levels, highly-sensitive CRP and fecal calprotectin were measured during the 8-week interval in 5 consecutive patients in clinical (Crohn’s Disease Activity Index < 150) and endoscopic (Rutgeerts scores 0–1) remission after one year of therapy with infliximab 3 mg/Kg. For comparison with reported standards, infliximab pharmacokinetics and inflammatory parameters were also tested in 6 Crohn’s disease patients who did not undergo surgery and who were in clinical remission while on infliximab 5 mg/Kg. Patients on low infliximab dose also underwent colonoscopy after 18 additional months of therapy.

Results

Highly sensitive CRP and fecal calprotectin increased in all patients during the 8-week interval. Infliximab trough levels were lower in patients treated with the low dose compared to controls (mean±SE: 2.0±0.3 vs 4.75±0.83 μg/mL respectively p<0.05). Infliximab antibodies were present in two of the subjects treated with low infliximab dose and in none of the controls. However, in low dose-treated patients after 18 additional months of therapy endoscopy continued to show mucosal remission and none of them developed clinical recurrence or side effects.

Conclusions

Patients treated with low infliximab doses had lower trough levels compared to patients treated with 5 mg/Kg and some developed antibodies to infliximab. However, low infliximab doses sustained clinical and endoscopic remission for a total of 30 months of treatment.

Investigating the link between disease activity and infliximab serum levels in rheumatoid arthritis patients

OBJECTIVES

The aim of this study was to examine the extent to which infliximab (IFX) serum levels impact disease activity in rheumatoid arthritis (RA) patients.

METHODS

In this cross sectional study, serum samples were taken prior to drug infusion from 60 RA patients who had been undergoing IFX therapy > 12 months as a first line of biological treatment. Patient IFX levels were tested and then associated with clinical disease activity. Three DAS28 cut-off points, <2.6, <3.2 and <5.1 were used to determine whether detectable IFX levels were any predictor of clinical disease activity. Logistic regression analysis was run to check other possible factors associated with RA clinical outcomes such as MTX concomitant use, CRP and ESR.

RESULTS

Sixteen (27%) out of the 60 patients tested negative; 28 (46%) presented subtherapeutic and 16 (27%) therapeutic IFX levels. Median IFX levels were higher in patients either in remission or showing low disease activity than in those with moderate and high disease activity (p=0.014). Significant association was found between IFX levels and clinical disease activity (p=0.001). Detectable levels of IFX shows better sensitivity and specificity to identify patients with DAS28<3.2 than to identify patients with DAS28<2.6 or DAS28<5.1. Conversely, the best DAS28 cut-off to identify detectable/undetectable IFX was 3.19, with AUC under ROC curve 0.804 (Sd.E 0.070), 76% specificity and 83% sensitivity (p<0.001). MTX use, CRP and ESR did not interfere with this association. Seven out of the 8 patients with anti-IFX antibodies presented DAS28>3.2 (p=0.005).

CONCLUSIONS

DAS28 and IFX serum levels were shown to have an inverse correlation. Undetectable IFX serum levels were associated to RA patients presenting DAS28>3.2 meaning that DAS28 <3.2 may be useful to clinicians to evaluate patient response to drug therapy.

Serum infliximab concentrations in psoriatic patients treated with infliximab: a systematic review

The efficacy of infliximab is influenced by individual variability in its pharmacokinetics and pharmacodynamics. Serum infliximab concentrations could therefore be related to the efficacy and tolerance of infliximab, and assist adjustment of treatment. The aim of this systematic review was to assess the value of measuring serum infliximab concentrations in psoriatic patients. A bibliographic search was performed on MEDLINE, CENTRAL, EMBASE, LILACS for original studies on serum infliximab concentrations in psoriatic patients treated with infliximab. Ten articles were included, representing evaluation of serum infliximab concentrations in 733 patients. Predictive value of higher serum infliximab concentrations on long-term response maintenance was suggested in 3 studies. There was no information regarding the value of such measurements for adjustment of infliximab dosage. Trough serum infliximab concentrations that are at least detectable (>0.1 mg/L) at steady state (week 22) seem to be associated with maintaining a clinical response in the long term.

A pharmacokinetic approach to model-guided design of infliximab schedules in ulcerative colitis patients

BACKGROUND

Infliximab, an anti-tumour necrosis factor approved for treatment of Crohn´s disease and ulcerative colitis, is administered at predefined interdose intervals. On insufficient response or loss of response, treatment can be intensified. The lack or loss of response is likely related to complex pharmacokinetics of infliximab.

AIMS

To explore optimal dosing strategies of infliximab in treatment-naïve patients with ulcerative colitis through predictive Monte Carlo simulations based on a validated population PK model.

METHODS

A population of 2,000 treatment-naïve patients was generated by Montecarlo simulation. Six dosing strategies for maintenance therapy were simulated on this population. Strategies 1 and 2 consisted on 5 mg/kg and 6 mg/kg doses, respectively, and 8 weeks inter-dose interval. Strategies 3 and 4 used Individualized doses, adjusted to albumin level, sex and body weight, and a fix interdose interval of 8 weeks to achieve a target trough concentration of 5 mg/L or 6 mg/L, respectively. Strategies 5 and 6 used a fix dose of 5 mg/kg and individualized inter-dose intervals, adjusted to the same covariates, to achieve a target concentration, of 5 mg/L or 6 mg/L, respectively.

RESULTS

Strategies 2-6 reached trough levels statistically higher than strategy 1 (p < 0.05). Strategy 5 proved to be the best dosing strategy. It was associated with a higher proportion of responder patients than strategy 1 (62 % vs. 40 %) without reaching higher peak concentrations.

CONCLUSIONS

Optimization of maintenance treatment of colitis with infliximab by a pharmacokinetic approach could benefit infliximab-naive patients with ulcerative colitis.