Optimised infliximab monotherapy is as effective as optimised combination therapy, but is associated with higher drug consumption in inflammatory bowel disease

Therapeutic drug monitoring in inflammatory bowel diseases. Position statement of the Spanish Working Group on Crohn's Disease and Ulcerative Colitis

The treatment of inflammatory bowel disease has undergone a significant transformation following the introduction of biologic drugs. Thanks to these drugs, treatment goals have evolved from clinical response and remission to more ambitious objectives, such as endoscopic or radiologic remission. However, even though biologics are highly effective, a significant percentage of patients will not achieve an initial response or may lose it over time. We know that there is a direct relationship between the trough concentrations of the biologic and its therapeutic efficacy, with more demanding therapeutic goals requiring higher drug levels, and inadequate exposure being common. Therapeutic drug monitoring of biologic medications, along with pharmacokinetic models, provides us with the possibility of offering a personalized approach to treatment for patients with IBD. Over the past few years, relevant information has accumulated regarding its utility during or after induction, as well as in the maintenance of biologic treatment, in reactive or proactive strategies, and prior to withdrawal or treatment de-escalation. The aim of this document is to establish recommendations regarding the utility of therapeutic drug monitoring of biologics in patients with inflammatory bowel disease, in different clinical practice scenarios, and to identify areas where its utility is evident, promising, or controversial.

Recent Advances in the Optimization of Anti-TNF Treatment in Patients with Inflammatory Bowel Disease

Despite the evolution in inflammatory bowel disease (IBD) management during the last 20 years owing to the advent of new advanced therapies, anti-TNF agents still remain the cornerstone of therapy for both Crohn's disease and ulcerative colitis. However, this does not only secure favorable outcomes for patients considering the progressive disease character and the high likelihood of primary or secondary loss of response. Therefore, trying to reach a better treatment approach and maximize the benefits anti-TNF agents offer, optimization strategies should be examined. It has been indicated that optimizing treatment with anti-TNF enhances drug efficacy and has been associated with improved disease outcomes and a complication-free disease course. From this perspective, we aim to provide an overview of currently available data and recent advances in the practices of anti-TNF treatment optimization. Special focus has been given to the role of therapeutic drug monitoring (TDM), as well as the utility of combining anti-TNF with an immunomodulator and the treat-to-target approach.

Pediatric inflammatory bowel disease: Fecal calprotectin response to Anti-tumor necrosis factor alpha

BACKGROUND

Fecal calprotectin (FC) is a marker of mucosal inflammation in inflammatory bowel disease (IBD). We aimed to assess the effect of anti-tumor necrosis factor alpha (TNFα) therapy on FC levels in children with IBD.

METHODS

The medical records of pediatric patients treated with anti-TNFα agents (2015-2020) were reviewed retrospectively. 63 patients had FC levels measured prior to anti TNFα induction with sequential measurements during follow-up. The main outcome measures were time to FC response according to cutoffs of 250, 150, 100 and 50 µgr/gr.

RESULTS

Mean age was 13.6 ± 3 years [females 28 (44.4%), Crohn's 55 (87%)]. Outcomes of < 250, < 150, < 100 and < 50 µgr/gr were achieved by 52 (82%), 51 (81%), 44 (70%) and 32 (50%), respectively. The median time for achieving these cutoffs was 4.8 (1.8-15.6), 7.9 (2.6-16.4), 10.0 (3.5-20.5) and 18.5 (7.0-64.7) months, respectively. Shorter time from diagnosis to treatment was associated with achievement of FC < 50 µgr/gr (p = 0.03). There was no association between age, disease type, anti-TNFα type, inflammatory markers, disease activity indices at baseline and induction anti-TNFα trough concentration and FC response.

CONCLUSIONS

FC response was achieved by the majority of patients treated with anti-TNFα within a short period of time. FC normalization in responders required almost one year.

IMPACT

Fecal calprotectin response was achieved by the majority of pediatric patients within a relatively short period of time after anti-TNFα induction and maintenance therapy. Fecal calprotectin normalization required an average period of approximately one year in responders. The faster response of fecal calprotectin is associated with shorter time from diagnosis to anti-TNFα treatment. Inflammatory bowel disease treating physicians should be aware of the relatively prolonged time to fecal calprotectin normalization and to allow enough time for anti-TNFα therapy to express its full potential prior to significant interventions.

Therapeutic Drug Monitoring of Biologics in Crohn's Disease

Reactive therapeutic drug monitoring (TDM) is considered the standard of care for optimizing biologics in inflammatory bowel disease (IBD) including Crohn's disease (CD). Preliminary data show that proactive TDM is associated with positive outcomes in IBD and can be also used to efficiently guide therapeutic decisions in specific clinical scenarios. Higher biological drug concentrations are associated with favorable therapeutic outcomes in specific IBD populations or phenotypes including pediatric CD, perianal fistulizing CD, small bowel CD, and following an ileocolonic resection for CD. Future perspectives of TDM include the use of rapid testing, pharmacogenomics, and pharmacokinetic dashboards toward individualized therapy.

Proactive infliximab optimisation using a pharmacokinetic dashboard versus standard of care in patients with Crohn's disease: study protocol for a randomised, controlled, multicentre, open-label study (the OPTIMIZE trial)

INTRODUCTION

Preliminary data indicates that proactive therapeutic drug monitoring (TDM) is associated with better outcomes compared with empiric dose escalation and/or reactive TDM, and that pharmacokinetic (PK) modelling can improve the precision of individual dosing schedules in Crohn's disease (CD). However, there are no data regarding the utility of a proactive TDM combined PK-dashboard starting early during the induction phase, when disease activity and drug clearance are greatest. The aim of this randomised, controlled, multicentre, open-label trial is to evaluate the efficacy and safety of a proactive TDM combined PK dashboard-driven infliximab dosing compared with standard of care (SOC) dosing in patients with moderately to severely active CD.

METHODS AND ANALYSIS

Eligible adolescent and adult (aged ≥16-80 years) patients with moderately to severely active CD will be randomised 1:1 to receive either infliximab monotherapy with proactive TDM using a PK dashboard (iDose, Projections Research) or SOC infliximab therapy, with or without a concomitant immunomodulator (IMM) (thiopurine or methotrexate) at the discretion of the investigator. The primary outcome of the study is the proportion of subjects with sustained corticosteroid-free clinical remission and no need for rescue therapy from week 14 throughout week 52. Rescue therapy is defined as any IFX dose escalation other than what is forecasted by iDose either done empirically or based on reactive TDM; addition of an IMM after week 2; reintroduction of corticosteroids after initial tapering; switch to another biologic or need for CD-related surgery. The secondary outcomes will include both efficacy and safety end points, such as endoscopic and biological remission, durability of response and CD-related surgery and hospitalisation.

ETHICS AND DISSEMINATION

The protocol has been approved by the Institutional Review Board Committee of the Beth Israel Deaconess Medical Center (IRB#:2021P000391). Results will be disseminated in peer-reviewed journals and presented at scientific meetings.

TRIAL REGISTRATION NUMBER

NCT04835506.

Patients With Low Drug Levels or Antibodies to a Prior Anti-Tumor Necrosis Factor Are More Likely to Develop Antibodies to a Subsequent Anti-Tumor Necrosis Factor

Therapeutic drug monitoring (TDM) with measurement of serum drug and antidrug antibodies (ADAb) is used widely to confirm therapeutic exposure, rule out immunogenicity, and optimize treatment of biologics in patients with inflammatory bowel diseases.¹ A recent genome-wide association study found the variant HLA-DQA1∗05 to increase the risk of development of antibodies against infliximab (IFX) and adalimumab (ADM) 2-fold, regardless of concomitant immunomodulator use.^2,3 However, there is currently limited evidence showing whether patients who develop antibodies to 1 anti-tumor necrosis factor (TNF) are prone to develop antibodies to the subsequent anti-TNF. Our aim was to investigate the risk of subsequent antibody development in cases (with ADAb to prior anti-TNF) versus control subjects (without ADAb to prior anti-TNF) using a large cohort of patients with inflammatory bowel diseases who underwent TDM with a drug-tolerant assay.

Therapeutic drug monitoring of biologics in inflammatory bowel disease: unmet needs and future perspectives

Therapeutic drug monitoring (TDM) has emerged as a useful tool for optimising the use of biologics, and in particular anti-tumour necrosis factor (anti-TNF) therapy, in inflammatory bowel disease (IBD). However, challenges remain and are hindering the widespread implementation of TDM in clinical practice. These barriers include identification of the optimal drug concentration to target, the lag time between sampling and results, and the proper interpretation of anti-drug antibody titres among different assays. Solutions to overcome these barriers include the harmonisation of TDM assays and the use of point-of-care testing. Other unmet needs include well designed prospective studies and randomised controlled trials focusing on proactive TDM, particularly during induction therapy. Future studies should also investigate the utility of TDM for biologics other than anti-TNF therapies in both IBD and other immune-mediated inflammatory diseases such as rheumatoid arthritis and psoriasis, and the use of pharmacokinetic modelling dashboards and pharmacogenetics towards individual personalised medicine.

Proactive therapeutic drug monitoring is more effective than conventional management in inducing fecal calprotectin remission in inflammatory bowel disease

BACKGROUND

Proactive therapeutic drug monitoring (pTDM) may improve treatment outcomes in inflammatory bowel disease.

AIMS AND METHODS

We compared 135 patients following a prospective pTDM protocol aiming at an infliximab trough level (IFXTL) between 5 and 10 μg/ml with sequential measurements of Fc, with 108 patients from a retrospective group under conventional management. We evaluated the rates of Fc remission (<250 μg/g) and other clinical outcomes at 2-year of follow-up.

RESULTS

pTDM associated with higher rates of Fc remission (69.6% vs. 50.0%; P = 0.002), and steroid-free clinical remission (78.4% vs. 55.2%, P = 0.028) with a trend for clinical remission (79.3% vs. 68.5%, P = 0.075). There was no difference in treatment discontinuation (P = 0.195), hospitalization (P = 0.156), and surgery (P = 0.110). Higher IFXTL associated with Fc remission at week 14 (6.59 vs. 2.96 μg/ml, P < 0.001), and at the end of follow-up (8.10 vs. 5.03 μg/ml, P = 0.001). In patients reaching Fc remission after week 14, IFXTL increased from week 14 to the end of follow-up (2.71 vs. 8.54 μg/ml, P < 0.001). Fc remission associated with higher rates of clinical (85.8% vs. 56.8% P < 0.001) and steroid-free clinical remission (86.9% vs. 50.0% P < 0.001), lower IFX discontinuation (8.8% vs. 36.8%, P < 0.001), and hospitalization (13.5% vs. 33.7%, P < 0.001), without significance for surgery (6.1% vs. 12.6%, P = 0.101).

CONCLUSION

pTDM was more effective than conventional management in inducing Fc remission which was associated with improved outcomes.

A Comprehensive Literature Review and Expert Consensus Statement on Therapeutic Drug Monitoring of Biologics in Inflammatory Bowel Disease

Therapeutic drug monitoring (TDM) of biologics is a rapidly evolving field. We aimed to provide a consensus statement regarding the clinical utility of TDM for biologics in inflammatory bowel disease (IBD). A modified Delphi method was applied to develop consensus statements. A comprehensive literature review was performed regarding TDM of biologic therapies in IBD, and 45 statements were subsequently formulated on the potential application of TDM in IBD. The statements, along with literature, were then presented to a panel of 10 gastroenterologists with expertise in IBD and TDM who anonymously rated them on a scale of 1-10 (1 = strongly disagree and 10 = strongly agree). An expert consensus development meeting was held virtually to review, discuss, refine, and reformulate statements that did not meet criteria for agreement or that were ambiguous. During the meeting, additional statements were proposed. Panelists then confidentially revoted, and statements rated ≥7 by 80% or more of the participants were accepted. During the virtual meeting, 8 statements were reworded, 7 new statements were proposed, and 19 statements were rerated. Consensus was finally reached in 48/49 statements. The panel agreed that reactive TDM should be used for all biologics for both primary nonresponse and secondary loss of response. It was recommended that treatment discontinuation should not be considered for infliximab or adalimumab until a drug concentration of at least 10-15 μg/mL was achieved. Consensus was also achieved regarding the utility of proactive TDM for anti-tumor necrosis factor therapy. It was recommended to perform proactive TDM after induction and at least once during maintenance. Consensus was achieved in most cases regarding the utility of TDM of biologics in IBD, specifically for reactive and proactive TDM of anti-tumor necrosis factors.

Higher Maintenance Adalimumab Trough Levels are Associated With Achievement of Advanced Remission Targets in Patients With Inflammatory Bowel Disease

BACKGROUND

Biomarker normalization and endoscopic remission are superior to clinical remission in achieving improved long-term clinical outcomes in patients with inflammatory bowel diseases.

GOAL

To study whether higher maintenance adalimumab levels are associated with clinical remission, biomarker normalization, and endoscopic remission.

STUDY

Data were collected retrospectively from the patients' medical records. We defined clinical remission as a Harvey Bradshaw Index ≤5 or a partial Mayo score ≤2 for Crohn's disease (CD) and ulcerative colitis (UC), respectively, biomarker normalization as a C-reactive protein <0.5 mg/dL and/or calprotectin <250 (mg/kg), endoscopic remission as a (simple endoscopic score-CD) ≤3/4 for ileal/extensive CD, respectively, or an endoscopic Mayo score ≤1 for UC, and deep remission as the combination of clinical and endoscopic remission with normal biomarkers.

RESULTS

Ninety-seven patients were included (82 CD and 15 UC). Patients who achieved clinical remission, biomarker normalization, or endoscopic remission had higher serum trough adalimumab levels compared with patients not in remission [mean (M)±standard error (SE)=8.98±0.78 vs. 5.92±0.96 μg/mL; P=0.016, 9.38±0.85 vs. 5.48±0.87 μg/mL; P=0.002; 9.13±0.88 vs. 6.02±0.77 μg/mL; P=0.019, respectively]. Receiver-operating curve analysis showed that an adalimumab level of ≥8.25 μg/mL was associated with deep remission (sensitivity 84%, specificity 70%, area under the curve 0.775; P<0.001).

CONCLUSION

Clinical remission, biomarker normalization, and endoscopic remission are positively associated with adalimumab trough levels. Adalimumab level of ≥8.25 μg/mL is associated with deep remission. This study provides additional data to guide therapeutic drug monitoring with adalimumab.

TNF-Alpha Blockers in Inflammatory Bowel Diseases: Practical Recommendations and a User's Guide: An Update

BACKGROUND

Anti-tumour necrosis factor-alpha (anti-TNF) antagonists have been the mainstay in the treatment of inflammatory bowel diseases (IBDs) for over 20 years.

SUMMARY

This review article aimed to provide an update on recent advances in TNF antagonist therapy for IBDs. Key Messages: Their position in the treatment algorithm has evolved to "rapid step-up therapy" or "top-down therapy" according to disease severity and patients' characteristics. Limitations of anti-TNF antagonists include loss of response in up to 30-50% of patients with or without the development of antibodies. Therapeutic drug monitoring should provide a tailored, personalized approach to this scenario. Recently, biosimilar agents have been approved for IBDs and are considered equivalent in efficacy to the originator.

Thiopurines in Inflammatory Bowel Disease. How to Optimize Thiopurines in the Biologic Era?

Thiopurines have been a cornerstone in the treatment of inflammatory bowel disease (IBD). Although they have been used for more than 50 years, there are still some unsolved issues about their efficacy and, also, some safety concerns, mainly the risk of myelosuppression and life-threatening lymphoproliferative disorders. Furthermore, the development of biological therapy raises the question whether there is still a role for thiopurines in the IBD treatment algorithm. On the other hand, limited cost and wide availability make thiopurines a reasonable option in settings of limited resources and increasing prevalence of IBD. In fact, there is a growing interest in optimizing thiopurine therapy, since pharmacogenomic findings suggest that a personalized approach based on the genotyping of some molecules involved in its metabolism could be useful to prevent side effects. Polymorphisms of thiopurine methyltransferase enzyme (TPMT) that result in low enzymatic activity have been associated with an increased risk of myelotoxicity, especially in Caucasians; however, in Asians it is assumed that the variants of nudix hydrolase 15 (NUDT15) are more relevant in the development of toxicity. Age is also important, since in elderly patients the risk of complications seems to be increased. Moreover, the primo-infection of Epstein Barr virus and cytomegalovirus under thiopurine treatment has been associated with severe lymphoproliferative disorders. In addition to assessing individual characteristics that may influence thiopurines treatment outcomes, this review also discusses other strategies to optimize the therapy. Low-dose thiopurines combined with allopurinol can be used in hypermethylators and in thiopurine-related hepatotoxicity. The measurement of metabolites could be useful to assess compliance, identify patients at risk of adverse events and also facilitating the management of refractory patients. Thioguanine is also a rescue therapy in patients with toxicity related to conventional thiopurine therapy. Finally, the current indications for thiopurines in monotherapy or in combination with biologics, as well as the optimal duration of treatment, are also reviewed.

The comparison of the three assays for determination of fecal calprotectin in inflammatory bowel disease

Introduction

Fecal calprotectin is a biomarker for monitoring inflammatory bowel disease (IBD) activity. Our aim, therefore, was to evaluate two new assays, the point of care test Quantum Blue and the Liaison Calprotectin with respect to the Calprest, commonly used assay, and to determine their performance for IBD diagnosis.

Materials and methods

We included 73 prospective patients with IBD. Fecal calprotectin was measured and analysed with the routine Calprest assay and two recently introduced assays, the Quantum Blue and the Liaison Calprotectin. Furthermore, we compared the results by Bland and Altman analysis, and Passing-Bablok regression.

Results

We observed no difference in median calprotectin values obtained by the Calprest (94.6 µg/g, 95%CI 66.5 to 166.1) and Liaison assay (101.0 µg/g, 95%CI 48.1 to 180.1) whereas significantly higher concentrations were obtained with the Quantum Blue assay (240.0 µg/g, 95%CI 119.9 to 353.2). The mean absolute and relative difference between the Calprest and Quantum Blue methods was statistically significant (- 162.3 µg/g and
- 143.1%). Mean absolute difference between the Calprest and Liaison calprotectin methods was positive (2.2 µg/g). The agreement between assays revealed that Quantum Blue and Calprest have fair agreement with Kappa coefficient of 0.38 (95%CI 0.26 to 0.51). Liaison Calprotectin and Calprest revealed moderate agreement with a weak Kappa coefficient of 0.47 (95%CI 0.32 to 0.62).

Conclusion

Clinicians should be aware of these differences between the assays and avoid comparison of their respective results.

Thiopurines and their optimization during infliximab induction and maintenance: A retrospective study in Crohn's disease

BACKGROUND AND AIM

Combining therapy with a thiopurine is favored when commencing infliximab in Crohn's disease; however, the optimal 6-thioguanine nucleotide (TGN) level and how long to continue thiopurines after induction are uncertain. We aimed to compare outcomes after induction and during maintenance in combination therapy versus infliximab monotherapy in Crohn's and to examine whether TGN levels were associated with outcomes.

METHODS

Crohn's patients induced with infliximab with or without concomitant thiopurines were retrospectively identified. Response to induction and clinical outcomes in subsequent 6-month maintenance semesters were analyzed. A TGN level ≥235 pmol/8 × 10⁸ red blood cells was considered therapeutic.

RESULTS

In 89 patients, response to induction was higher in combination therapy than monotherapy (74 vs 47%, P = 0.04). This benefit was only seen in patients with a therapeutic TGN (odds ratio 3.72, confidence interval 1.07-13.0, P = 0.04). Combination therapy during induction yielded a three times longer time to subsequent need for treatment escalation or treatment failure compared with monotherapy (29 vs 9 months, P = 0.01), with both therapeutic and subtherapeutic TGNs independent predictors on multivariate analysis. Among 370 semesters, there was no difference in outcomes between combination therapy and monotherapy (P = 0.42), nor when combination semesters were stratified by therapeutic versus subtherapeutic TGN (P = 0.56). In semester 1 only, a significantly higher remission rate was observed with therapeutic compared with subtherapeutic TGN (76% vs 33%, P = 0.02).

CONCLUSIONS

Combination therapy dosed with an optimized thiopurine was superior to infliximab monotherapy for induction of response, durability of response, and clinical outcomes in the first 6 months following induction. Thereafter, combination therapy yielded no clinical advantage, supporting consideration of thiopurine withdrawal on a case-by-case basis.

Is It Useful to Monitor Thiopurine Metabolites in Pediatric Patients with Crohn's Disease on Combination Therapy? A Multicenter Prospective Observational Study

BACKGROUND

The additional value of azathioprine concomitant treatment on infliximab pharmacokinetics in children is not well described yet.

AIMS

In the present study, we aimed to describe the relationship between thiopurine metabolite levels, infliximab trough levels, anti-IFX antibody formation, and clinical and laboratory markers of disease activity in pediatric patients with Crohn's disease, and to assess non-adherence.

METHODS

Data were collected prospectively during repeated visits from pediatric patients followed for Crohn's disease in two Czech pediatric inflammatory bowel disease centers between January 2016 and June 2017. Thiopurine metabolites (6-thioguanine and 6-methylmercaptopurine) were measured by high-performance liquid chromatography. Infliximab trough levels and anti-IFX antibody serum levels were measured routinely by ELISA. The risk of loss of response to infliximab therapy was also assessed.

RESULTS

A significant association between infliximab serum levels and 6-thioguanine erythrocyte levels was observed when tested as categorical variables (63 patients, 321 observations). To predict infliximab levels > 5 µg/mL, we propose a 6-thioguanine cutoff of 278 pmol/8 × 10⁸ erythrocytes (sensitivity, 0.799; specificity, 0.347). A higher loss-of-response-to-infliximab rate (tested in a subgroup of 51 patients) was observed in patients with undetectable 6-thioguanine levels than in those with detectable levels (p = 0.026). Non-adherence to azathioprine therapy was suspected in 20% of patients.

CONCLUSION

Thiopurine metabolite monitoring in pediatric patients with Crohn's disease is useful when optimizing combination therapy. Pediatric patients with undetectable 6-thioguanine levels are more likely to lose response to infliximab therapy. When targeting optimal infliximab levels, the 6-thioguanine cutoff levels in children appear to be higher than in adults.

Infliximab therapy intensification based on endoscopic activity is related to suppress treatment discontinuation in patients with Crohn disease: A retrospective cohort study

ABSTRACT

Administering double doses of infliximab or shortening its dosing interval for patients with Crohn disease who experience a loss of response to treatment is an accepted treatment method; however, the effectiveness and appropriate timing of treatment intensification remain unclear. We examined the treatment outcomes of patients with Crohn disease receiving infliximab therapy intensification.Among 430 patients with Crohn disease who were seen at our related facilities from July 2002 to July 2018, 46 patients (30 men and 16 women) who were followed up for diminished infliximab effects for >1 year after therapy intensification were included in this study. The relationship between patient background and continuation of therapy intensification was retrospectively examined through a logistic regression analysis.Among the 46 patients, 67.4% (31 cases) continued therapy intensification for 12 months. The treatment discontinuation rate after 12 months (7.1% vs 43.8%, P = .015) and the C-reactive protein levels at the start of therapy intensification (P = .0050) were significantly lower in the group in which treatment was strengthened due to remaining endoscopic findings (n = 14) than that due to clinical symptoms (n = 32). There was no significant difference in the rates of treatment discontinuation after 12 months of treatment strengthening between patients receiving double doses (n = 34) and those with shortened dosing intervals (n = 12).Infliximab treatment discontinuation seems to be less likely to occur in patients with Crohn disease who are receiving infliximab treatment intensification based on endoscopic findings of exacerbations than in patients whose treatment is based on clinical symptoms.

Endoscopic remission can be predicted by golimumab concentrations in patients with ulcerative colitis treated with the changed label

BACKGROUND

In 2018, the European Medicines Agency (EMA) replaced a fixed 50 mg every 4-week maintenance regimen of golimumab for ulcerative colitis (UC) patients weighing <80 kg with new, flexible dosing that allows reactive dose optimization to 100 mg if clinically needed. We analyzed the endoscopic remission rates and pharmacokinetics of this new dosing regimen in real-life settings.

METHODS

We prospectively recruited 30 consecutive (17 with body weight <80 kg) patients with UC who received golimumab with the new EMA label. The primary endpoint was endoscopic remission (Mayo ≤1) assessed by centrally-read endoscopy at week 14 and year 1. Golimumab concentrations, measured at nine prespecified timepoints, were correlated with endoscopic remission and identified cut-offs.

RESULTS

Endoscopic remission was achieved in 15/30 (50%) and 10/30 (33%) patients at week 14 and year 1, respectively. Reactive dose optimization to 100 mg maintenance was needed in 13/17 (76%) patients. Golimumab concentrations at week 6 predicted week 14 and year 1 endoscopic remission. Week 6 concentrations >10.7 µg/ml were a strong predictor for achievement and maintenance of endoscopic remission during the first year of treatment, while concentrations <5.1 µg/ml identified the opposite.

CONCLUSION

One-third of the patients reached and maintained endoscopic remission during the first year of golimumab treatment, but the need for dose optimization to 100 mg every 4 weeks of maintenance was high in patients weighing <80 kg. Golimumab concentrations <5.1 µg/ml at week 6 identified patients who are unlikely to reach and maintain endoscopic remission with the new, flexible EMA label.

De-escalation of medical therapy in inflammatory bowel disease

Treatment strategies for inflammatory bowel disease (IBD) now increasingly target deep remission, yet the resultant more aggressive use of medical therapy is associated with potentially serious adverse events and significant costs. It is, therefore, of vital importance to consider when, how and in whom medical therapy may be safely de-escalated. This issue is of great potential relevance in the current SARS-Cov-2 pandemic. In this review, we first discuss the rationale for drug withdrawal in IBD, before considering the available data on withdrawal of 5-aminosalicylates (5-ASA), immunomodulators (IM) and biological therapy in both ulcerative colitis (UC) and Crohn's Disease (CD). We consider how to identify patients most appropriate for drug withdrawal and outline a potential monitoring strategy for the early detection of relapse following drug withdrawal. We conclude with important future perspectives in this challenging field, and highlight ongoing trials that are likely to shape practice in the years to come.

Therapeutic drug monitoring in patients on biologics: lessons from gastroenterology

PURPOSE OF REVIEW

To give an overview on the role of therapeutic drug monitoring (TDM) of biologics in patients with inflammatory bowel disease (IBD).

RECENT FINDINGS

Numerous prospective exposure-response relationship studies and post-hoc analyses of randomized controlled trials (RCTs) show a positive correlation between biologic drug concentrations and favorable clinical outcomes in IBD. These studies also demonstrate that higher drug concentrations appear to be needed to achieve more stringent objective therapeutic outcomes. Reactive TDM rationalizes the management of primary nonresponse and secondary loss of response to antitumor necrosis factor (anti-TNF) therapy and is more cost-effective when compared with empiric dose optimization. Furthermore, recent data suggest that proactive TDM, with the goal of targeting a threshold drug concentration, is associated with better therapeutic outcomes when compared with empiric dose escalation and/or reactive TDM of infliximab or adalimumab. Finally, proactive TDM can also efficiently guide infliximab de-escalation or discontinuation in patients with IBD in remission.

SUMMARY

Reactive TDM is currently considered as standard of care, whereas proactive TDM is emerging as a new therapeutic strategy for better optimizing anti-TNF therapy in IBD. However, more data from prospective studies are needed before a wide implementation of TDM-based algorithms in real life clinical practice for newer biologics.

Optimized timing of using infliximab in perianal fistulizing Crohn's disease

Infliximab (IFX), as a drug of first-line therapy, can alter the natural progression of Crohn’s disease (CD), promote mucosal healing and reduce complications, hospitalizations, and the incidence of surgery. Perianal fistulas are responsible for the refractoriness of CD and represent a more aggressive disease. IFX has been demonstrated as the most effective drug for the treatment of perianal fistulizing CD. Unfortunately, a significant proportion of patients only partially respond to IFX, and optimization of the therapeutic strategy may increase clinical remission. There is a significant association between serum drug concentrations and the rates of fistula healing. Higher IFX levels during induction are associated with a complete fistula response in these patients. Given the apparent relapse of perianal fistulizing CD, maintenance therapy with IFX over a longer period seems to be more beneficial. It appears that patients without deep remission are at an increased risk of relapse after stopping anti-tumor necrosis factor agents. Thus, only patients in prolonged clinical remission should be considered for withdrawal of IFX treatment when biomarker and endoscopic remission is demonstrated, especially when the hyperintense signals of fistulas on T2-weighed images have disappeared on magnetic resonance imaging. Fundamentally, the optimal timing of IFX use is highly individualized and should be determined by a multidisciplinary team.

TDM of Anti-TNF Agents: The Importance of Being Active!

Therapeutic drug monitoring (TDM) for anti-TNFα agents hass gained an increased momentum; although it is surely recommended in case of loss of response, its usefulness during maintenance therapy is still debated. Fernandes et al have added useful information in this regard.

Positive pharmacokinetic effect of azathioprine co-medication on infliximab trough levels is dose-dependent

BACKGROUND

Thiopurines seem to have positive effect on the pharmacokinetics of anti-tumor necrosis factor biologics. It has been suggested that a reduced dose of thiopurines is sufficient to achieve this synergism.

AIMS

To assess the differences of infliximab (IFX) trough levels according to the dose of concomitantly used azathioprine (AZA).

PATIENTS & METHODS

All IBD patients treated with IFX (Remicade^®) in two IBD centres between November 2015 and April 2017 were eligible. Infliximab trough levels were assessed by ELISA (Ridascreen^®, R-Biopharm). The differences in IFX trough levels according to AZA dose were analyzed statistically.

RESULTS

In total, 125 patients were included, 42 pts (33.6%) on infliximab monotherapy, 83 pts (66.4%) using combined immune suppression. The respective median IFX levels according to AZA dose were as follows: group 1 (no concomitant AZA) 2.83 μg/ml (range 0-12); group 2 (AZA dose less than 1 mg/kg) 4.91 μg/ml (range 0.09-15.36); group 3 (AZA dose 1 < 2 mg/kg) 5.67 (range 0.16-16.97); group 4 (AZA dose above 2 mg/kg) 7.53 μg/ml (range 1.15-8.73). The differences in IFX trough levels between the respective groups according to AZA dose were statistically significant (p = 0.0159).

CONCLUSION

The positive effect of azathioprine on infliximab levels seems to be dependent on the dose of concomitantly used azathioprine.

Biologic therapies for Crohn's disease: optimising the old and maximising the new

The era of biologic agents for the treatment of Crohn’s disease has brought about significant benefits for patients, and since the introduction of infliximab at the turn of the century, the entire field has moved on rapidly. Clinicians now have multiple agents at their disposal and a choice between several different anti-inflammatory mechanisms of action. This has allowed unprecedented improvements not only in symptoms and quality of life for patients previously refractory to conventional treatments but also for demonstrated healing of the intestinal mucosa and resolution of perianal fistulation. However, despite the undisputed efficacy of these agents, there remains a significant proportion of patients who fail to gain a meaningful benefit. Through years of studying infliximab and its counterpart anti-tumour necrosis factor (anti-TNF) agent, adalimumab, we now understand that strategies such as combining use with a conventional immunomodulator or measuring serum levels can help to optimise outcomes and reduce the proportion of patients for whom treatment fails. Work is ongoing to understand whether these principles apply to newer biologics such as vedolizumab and ustekinumab. In addition, novel approaches are being investigated in an attempt to maximise the benefit that these agents could offer. In this article, we summarise these new understandings and consider ways in which they could be integrated into clinical practice for the benefit of patients.

Therapeutic drug monitoring with biologic agents in immune mediated inflammatory diseases

: Most exposure-response relationship studies show a positive correlation between biologic drug concentrations and favorable therapeutic outcomes in IMID with higher drug concentrations typically associated with more objective outcomes. Clinically, reactive TDM rationalizes the management of PNR and SLR to anti-tumor necrosis factor therapy and is emerging as the new standard of care in IBD as it is also more cost-effective than empiric dose escalation. Preliminary data suggest that proactive TDM with the goal to achieve a threshold drug concentration is associated with better therapeutic outcomes when compared to empiric drug optimization and/or reactive TDM of infliximab and adalimumab in IBD. However, more data from well-designed prospective studies are needed to prove the benefit of TDM-based algorithms in real life clinical practice in IMID.

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

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