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

Optimized Infliximab Induction Predicts Better Long-Term Clinical and Biomarker Outcomes Compared to Standard Induction Dosing

OBJECTIVES

To evaluate the efficacy of standard and optimized infliximab induction dosing in attaining corticosteroid (CS) free clinical remission at week 52 and the effect that post-induction trough levels have on long-term outcome.

METHODS

Inflammatory bowel disease (IBD) patients ≤18 years commenced on infliximab between August 1, 2016, and August 1, 2018, from Vancouver, Canada, and Glasgow, Scotland, were included. The Glasgow cohort followed standard induction while the Vancouver cohort undertook induction optimization based on clinical, biomarker, and proactive infliximab trough levels. Baseline characteristics and laboratory values were documented.

RESULTS

In total, 140 children were included [median age 14.1 years (interquartile range (IQR) 12.0-16.0)]; 54% male. CS-free clinical remission at week 52 was higher in the optimized group compared to the standard cohort [65/78 (83%) vs. 32/62 (52%), P < 0.001]. Combined CS-free clinical and biomarker remission (CRP < 5 mg/L) was also higher in the optimized compared to the standard cohort [65/78 (83%) vs 25/62 (40%), P < 0.001]. The median post-induction trough level was higher in children who were in CS-free clinical remission at week 52 [3.6 mg/L (1.5-7.1)] vs. those who were not [2.0 mg/L (0.8-4.1), P = 0.04]. The odds of attaining a therapeutic post-induction trough level were almost 4-fold higher in the optimized group than the standard cohort (OR 3.97, 95% CI: 1.89-8.68, P < 0.001).

CONCLUSIONS

Standard infliximab induction resulted in less favorable long-term outcomes for pediatric IBD patients. Optimizing induction using clinical, biomarker, and proactive trough levels resulted in higher post-induction trough levels and a greater odds of attaining long-term clinical remission.

Biomarkers for Optimization and Personalization of Anti-TNFs in Pediatric Inflammatory Bowel Disease

The use of biological drugs has improved outcomes in pediatric inflammatory bowel disease (IBD). Prediction of the response to biological drugs would be extremely useful in IBD, and even more so in children, who are still growing physically and psychologically. Specific clinical, biochemical, and genetic parameters are considered predictive of response to biological drugs, although few studies have been carried out in children with IBD. In this review, we present current evidence on biological treatments used in pediatric IBD and the available biomarkers of response. We examine demographics, clinical characteristics, biomarkers (genetic, genomic, and cellular), and microbiota.

Advances in Therapeutic Drug Monitoring in Biologic Therapies for Pediatric Inflammatory Bowel Disease

In the current era of treat-to-target strategies, therapeutic drug monitoring (TDM) has emerged as a potential tool in optimizing the efficacy of biologics for children diagnosed with inflammatory bowel disease (IBD). The incorporation of TDM into treatment algorithms, however, has proven to be complex. "Proactive" TDM is emerging as a therapeutic strategy due to a recently published pediatric RCT showing a clear benefit of "proactive" TDM in anti-TNF therapy. However, target therapeutic values for different biologics for different disease states [ulcerative colitis (UC) vs. Crohn's disease (CD)] and different periods of disease activity (induction vs. remission) require further definition. This is especially true in pediatrics where the therapeutic armamentarium is limited, and fixed weight-based dosing may predispose to increased clearance leading to decreased drug exposure and subsequent loss of response (pharmacokinetic and/or immunogenic). Model-based dosing for biologics offers an exciting insight into dose individualization thereby minimizing the chances of losing response. Similarly, point-of-care testing promises real-time assessment of drug levels and individualized decision-making. In the current clinical realm, TDM is being used to prolong drug durability and efficacy and prevent loss of response. Ongoing innovations may transform it into a personalized tool to achieve optimal therapeutic endpoints.

Genetic Predictors of Long-term Response to Antitumor Necrosis Factor Agents in Pediatric Inflammatory Bowel Disease

OBJECTIVES

Inflammatory bowel disease (IBD) is more complex in children and they will have to live with the disease for much longer. For this reason, it is necessary to optimize treatment. The polymorphisms associated with the response to anti-tumor necrosis factor (TNF) drugs in adults with IBD have not been analyzed in children. The aim of the study was to identify genetic variants associated with the long-term response to anti-TNF drugs in children with IBD.

METHODS

An observational, longitudinal, ambispective cohort's study was conducted. We recruited 209 anti-TNF-treated children diagnosed with IBD and genotyped 21 polymorphisms previously studied in adults with Crohn disease (CD) using real-time PCR. The association between single-nucleotide polymorphisms (SNPs) and time-to-failure was analyzed using the log-rank test.

RESULTS

After multivariate analysis, 3 SNPs in IL10, IL17A and IL6 were significantly associated with response to anti-TNF treatment among patients diagnosed with CD (rs1800872-HR, 4.749 (95% confidence interval [CI] 1.156-19.517), P value < 0.05; rs2275913-HR, 0.320 [95% CI 0.111-0.920], P value  < 0.05; and rs10499563-HR, 0.210 [95% CI 0.047-0.947], P value 0.05, respectively). None of these SNPs were associated with response to infliximab in adults diagnosed with CD. Among patients diagnosed with ulcerative colitis (UC), 1 SNP in LY96 was significantly associated with response to anti-TNF treatment (rs-11465996-HR, 10.220 [95% CI 1.849-56.504] P value < 0.05).

CONCLUSIONS

Genotyping of these DNA variants before starting treatment may help to identify children who are long-term responders to anti-TNF drugs, and thus tailor treatment of pediatric IBD.

Pharmacogenetics of trough serum anti-TNF levels in paediatric inflammatory bowel disease

AIMS

Identifying DNA variants associated with trough serum anti-tumour necrosis factor (TNF) levels could predict response to treatment in inflammatory bowel disease (IBD). To date, no specific studies have been performed in children. The aim of this study was to identify genetic variants associated with trough serum anti-TNF levels and whether these variants are differential markers for infliximab and adalimumab.

METHODS

We included 154 children (age < 18 years) from 17 hospitals who had been diagnosed with IBD and actively treated with infliximab or adalimumab. Twenty-one polymorphisms were genotyped using real-time PCR. Trough serum anti-TNF levels were measured using enzyme-linked immunosorbent assay (ELISA). The association between DNA polymorphisms and the therapeutic range or the absolute values of anti-TNF drugs was analysed by Fisher exact test, student's t-test and logistic regression.

RESULTS

The variants rs5030728 (TLR4) and rs11465996 (LY96) were associated with subtherapeutic infliximab levels. rs1816702 (TLR2) was associated with supratherapeutic levels and rs3397 (TNFRSF1B) with subtherapeutic levels of adalimumab (P < .05). In addition, rs1816702 (TLR2) and rs2569190 (CD14) were associated with absolute values of trough serum adalimumab, and rs2569190 (CD14) was associated with absolute values of trough serum adalimumab and infliximab (P < .05).

CONCLUSION

Genotyping of these DNA variants before starting treatment may help to select the best anti-TNF drug in paediatric patients. The SNP rs1816702 is the most promising marker for tailoring the anti-TNF regimen in children with IBD. For the first time, DNA variants are associated with trough serum anti-TNF levels.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

Background/Aims

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

Methods

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

Results

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

Conclusions

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

Infliximab in young paediatric IBD patients: it is all about the dosing

Infliximab (IFX) is administered intravenously using weight-based dosing (5 mg/kg) in inflammatory bowel disease (IBD) patients. Our hypothesis is that especially young children need a more intensive treatment regimen than the current weight-based dose administration. We aimed to assess IFX pharmacokinetics (PK), based on existing therapeutic drug monitoring (TDM) data in IBD patients < 10 years. TDM data were collected retrospectively in 14 centres. Children treated with IFX were included if IFX was started as IBD treatment at age < 10 years (young patients, YP) and PK data were available. Older IBD patients aged 10-18 years were used as controls (older patients, OP). Two hundred and fifteen paediatric inflammatory bowel disease (PIBD) patients were eligible for the study (110 < 10 year; 105 ≥ 10 years). Median age was 8.3 years (IQR 6.9-8.9) in YP compared with 14.3 years (IQR 12.8-15.6) in OP at the start of IFX. At the start of maintenance treatment, 72% of YP had trough levels below therapeutic range (< 5.4 μg/mL). After 1 year of scheduled IFX maintenance treatment, YP required a significantly higher dose per 8 weeks compared with OP (YP; 9.0 mg/kg (IQR 5.0-12.9) vs. OP; 5.5 mg/kg (IQR 5.0-9.3); p < 0.001). The chance to develop antibodies to infliximab was relatively lower in OP than YP (0.329 (95% CI - 1.2 to - 1.01); p < 0.001), while the overall duration of response to IFX was not significantly different (after 2 years 53% (n = 29) in YP vs. 58% (n = 45) in OP; p = 0.56).Conclusion: Intensification of the induction scheme is suggested for PIBD patients aged < 10 years. What is Known? •Infliximab trough levels of paediatric IBD patients are influenced by several factors as dosing scheme, antibodies and inflammatory markers. •In 4.5-30% of the paediatric IBD patients, infliximab treatment was stopped within the first year. What is New? •The majority of young PIBD (< 10 years) have inadequate IFX trough levels at the start of maintenance treatment. •Young PIBD patients (< 10 years) were in need of a more intensive treatment regimen compared with older paediatric patients during 1 year of IFX treatment. •The chance to develop antibodies to infliximab was relatively higher in young PIBD patients (< 10 years).

Adequate Infliximab Exposure During Induction Predicts Remission in Paediatric Patients With Inflammatory Bowel Disease

OBJECTIVES

Therapeutic drug monitoring has been proposed as a useful tool in the management of infliximab (IFX) treated patients with inflammatory bowel disease. The aim of this retrospective study was to determine whether IFX trough levels after induction therapy are predictive for outcome at week 52.

METHODS

All pediatric patients with inflammatory bowel disease receiving maintenance IFX at our centre, with IFX trough level available at their first maintenance infusion and a follow-up of at least 52 weeks were included. IFX induction regimens could be intensified at the discretion of the treating physician. All children received proactive drug monitoring during maintenance with dose adaptation aiming to target a therapeutic window of 3 to 7 μg/mL.

RESULTS

We included 35 children (23 with Crohn disease and 12 with ulcerative colitis). Median IFX trough levels just before the first maintenance infusion were significantly higher in children achieving clinical (4.6 μg/mL [2.7-11.8] vs 1.5 μg/mL [0.9-3.0]), biological (4.6 μg/mL [2.5-10.3] vs 2.6 μg/mL [0.3-3.2]) and combined clinical/biological remission (6.0 μg/mL [3.2-12.0] vs 2.6 μg/mL [1.1-3.2]) at week 52 compared to children not meeting these criteria (all P ≤ 0.002). Binary logistic regression identified these trough levels as the only predictor for the same outcomes with an odds ratio (95% confidence interval) of 2.083 (1.085-3.998), 2.203 (1.101-4.408), and 2.264 (1.096-4.680), respectively (all P < 0.05).

CONCLUSIONS

Adequate IFX exposure during induction therapy is associated with better clinical and/or biological remission at week 52. Postinduction IFX trough levels were the only predictor for clinical and/or biological remission at week 52.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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