Recent studies indicate that proactive therapeutic drug monitoring (TDM) can improve clinical outcomes in patients with inflammatory bowel disease (IBD) treated with infliximab. Repetitive infliximab trough level (IFX TL) measurements for proactive TDM may increase patient inconvenience and medical costs. Therefore, we aimed to determine the optimal interval for TDM during infliximab maintenance therapy in patients with IBD.

A prospective cohort study was performed on the patients with IBD who were in clinical remission on infliximab maintenance therapy and had IFX TL ≥ 3 μg/mL after one-time dose optimization. Infliximab TL were measured before each infliximab infusion to identify the pharmacokinetic (PK) relapse (two consecutive IFX TL < 3 μg/mL). Kaplan-Meier method was used to calculate the time to PK relapse.

A total of 103 patients were enrolled and followed for a median of 18.5 months. PK relapse occurred in 19 patients (18.5%), with a higher rate of PK relapse in patients with IFX TL 3-5 μg/mL (16/60, 26.7%) compared to those with IFX TL ≥ 5 μg/mL (3/43, 7.0%). Kaplan-Meier survival time to maintain 95%, 90%, 85%, 80%, and 75% therapeutic IFX TL persistence rate without PK relapse was 4.1, 10.3, 13.3, 14.3, and 19.8 months, respectively. Log-rank test showed that therapeutic IFX TL persistence rates were significantly lower in patients with IFX TL 3-5 μg/mL group compared to those with IFX TL ≥ 5 μg/mL group (p = 0.010). Kaplan-Meier retention time to maintain 85% therapeutic IFX TL persistence rate without PK relapse was 10.3 months in IFX TL 3-5 μg/mL group and 20.2 months in IFX TL ≥ 5 μg/mL group, respectively.

Proactive TDM measuring with IFX TL annually may be helpful in maintaining therapeutic IFX TL ≥ 3 μg/mL in 85% of patients with IBD and clinical remission on infliximab maintenance therapy.

To evaluate risk factors associated with development of anti-adalimumab antibodies (AAA) in patients with non-infectious uveitis treated with adalimumab.

A retrospective, cross-sectional, case-control study was done evaluating patients with non-infectious uveitis treated with adalimumab for at least 12 months and have undergone testing for AAA levels. Demographics, clinical characteristics, grading of ocular inflammation, and previous and concomitant immunomodulatory therapy were assessed. Univariate and multivariate analysis were done to estimate odds ratio (OR) with 95% confidence intervals for the various risk factors.

A total of 31 patients were included in the analysis, in which 12 patients who tested positive (Group 1) were matched with 19 patients who tested negative for AAA (Group 2). The groups differed significantly in terms of sex (female) (91.7% vs 52.6%, p = 0.046), presence of systemic disease (91.7% vs 42.1%, p = 0.008), and presence of anterior chamber inflammation at baseline (100% vs 63.2%, p = 0.026). A history of interruption in anti-TNF therapy prior to starting or restarting adalimumab was found to have an increased odds for development of AAA (OR 16.89 [2.92, 107.11], p = 0.008), as well as flare-ups (reactivation of disease) during adalimumab therapy (OR 6.77 [1.80, 61.80], p = 0.027). Weekly dosing of adalimumab was shown to decrease odds of AAA development (OR 0.34 [0.02, 0.70], p = 0.040), while concomitant anti-metabolite therapy was not shown to be a statistically significant protective factor (OR 2.22 [0.50, 9.96], p = 0.148).

History of interruption in anti-TNF therapy and flare during adalimumab were associated with development of AAA, while weekly dosing of adalimumab was protective against AAA. Identification of those with higher risk of developing AAA may guide in clinical decision making to optimize management for these patients.

Therapeutic drug monitoring (TDM) is a useful strategy to optimize biologic medications for inflammatory bowel disease not responsive to standard dosing regimens. TDM is cost effective for anti-tumor necrosis factor agents in the setting of loss of response (reactive TDM). Optimizing drug dosing when patients are in remission (proactive TDM) may be beneficial in certain circumstances. However, frequently the serum drug concentration in isolation becomes the focus TDM. Additionally, the lines of reactive and proactive TDM can quickly blur in many common clinical settings. Physicians employing a TDM based strategy need to place the drug concentration in context with the inflammatory status of the patient, the underlying pharmacokinetics and pharmacodynamics of the drug, the risk of immunogenicity, and the therapeutic goals for the patient. Physicians should understand the limits of TDM and feel comfortable making therapeutic decisions with imperfect information. The goal of this narrative review is to provide a framework of questions that physicians can use to employ TDM effectively in practice.

Recent clinical findings showed proactive therapeutic drug monitoring (TDM) of adalimumab (ADL) to improve sustained remission rate in pediatric patients with Crohn's disease (CD). The present study aimed to evaluate the potential cost-effectiveness of proactive versus reactive TDM of ADL in pediatric patients with CD from the perspective of the US health-care provider.

A Markov model was constructed to estimate outcomes of proactive versus reactive TDM of ADL in a hypothetical cohort of pediatric CD patients who were in remission on ADL maintenance treatment. Model inputs were derived from published literature and public data. Model outcomes included CD-related direct medical cost and quality-adjusted life-years (QALYs). Sensitivity analyses were performed to examine the robustness of base-case results.

When compared with the reactive TDM group, the proactive TDM group saved 0.1960 QALYs at lower cost by USD2021 over a 3-year time frame in base-case analysis. One-way sensitivity analysis showed the ADL drug cost to be the most influential factor. Probabilistic sensitivity analysis of 10 000 Monte-Carlo simulations found the proactive TDM group to gain 0.1958 QALYs (95% confidence interval [CI] 0.1950-0.1966; P < 0.001) and save USD2037 (95%CI USD1943-2131; P < 0.001).

Proactive TDM for ADL seems to gain higher QALYs at lower cost in pediatric CD patients.

There is a growing body of primary evidence on the cost-effectiveness of applying therapeutic drug monitoring (TDM) for inflammatory bowel disease (IBD) management with various drug therapies and strategies.

The aim of this study was to conduct a systematic review on model-based cost-effectiveness analyses of applying TDM for IBD management.

Literature search was conducted (up to October 2019) in Medline (Ovid), Embase (Ovid), Web of Science, Scopus, CINAHL Complete, and the Centre for Reviews and Dissemination. Studies published in the English language that met inclusion criteria were included: (1) patients with IBD, (2) TDM-based treatment was compared with a comparator, (3) types of analysis were cost-benefit, cost-consequence, cost-effectiveness, cost-utility, or cost analysis, and (4) analyses conducted by model-based evaluation. The study quality was assessed using Consolidated Health Economic Evaluation Reporting Standards.

Six studies on drug monitoring for IBD patients (1 azathioprine and 5 infliximab) published in 2005 to 2019 were included. All studies targeted on patients with Crohn's disease and reported TDM strategies to save cost when comparing with standard care. Four analyses evaluated both economic and clinical outcomes. Three analyses found the TDM strategies (for treatment initiation, advancement of therapy, or proactive monitoring) to improve clinical outcomes. One study found TDM strategies (reflex testing and concurrent testing) to gain lower quality-adjusted life years than standard care. Four of six (66.7%) studies achieved good to excellent rankings in quality assessment.

Compared with standard treatment without TDM, the TDM-guided strategies were consistently found to be cost-saving or cost-effective.

Specific and sensitive analytical techniques to quantify therapeutic monoclonal antibodies (mAbs) are required for therapeutic drug monitoring. The quantification of mAbs has been historically performed using enzyme-linked immunosorbent assays (ELISAs), for which the limitations in terms of specificity have led to the development of alternative analytical strategies.

Here, we describe the validation of a liquid chromatography tandem mass-spectrometry (LC-MS/MS) method for the simultaneous quantification of rituximab (RTX - anti-CD20) and eculizumab (ECU - anti-C5). Sample preparation was based on our previously published method, using protein G purification and trypsin digestion. A new specific peptide for RTX, containing an N-terminal pyroglutamine and a trypsin miss-cleavage, enables better sensitivity, while peptide of ECU was chosen thanks to an in silico trypsin digestion and the Skyline® software. Full-length stable-isotope-labeled adalimumab was added to plasma samples as an internal standard. RTX in 50 human serum samples was quantified by LC-MS/MS and the concentrations obtained compared to those obtained with two commercial ELISA kits (Lisa Tracker® and Promonitor®).

Calibration curves were linear from 1 to 200 µg.mL^-1 for RTX and 5 to 200 µg.mL^-1 for ECU, and within-day and between-day accuracy and precision fulfilled Food and Drug Administration validation criteria. Comparison of the LC-MS/MS method with ELISA showed a negligible bias with the Lisa Tracker® kit (4%), but significant bias with the Promonitor® assay (mean underestimation of 69% for the Promonitor® assay).

This new LC-MS/MS method allows the simultaneous quantification of RTX and ECU in human samples and could be used for therapeutic drug monitoring.

Medication costs in inflammatory bowel disease (IBD) are now the principal driver of health care costs. Cost-effective strategies to optimize and rationalize treatment are therefore necessary.

A systematic review until April 30, 2018, was performed to identify economic evaluations of strategies to optimize infliximab, adalimumab, and immunomodulators for the treatment of IBD in adults. A qualitative synthesis of the identified studies was performed.

Seventy articles were identified that met the inclusion criteria. Adalimumab seems cost-effective compared with infliximab as maintenance therapy for moderate to severe Crohn's disease (CD). Infusion costs are a significant additional treatment cost with infliximab. However, other studies found biosimilar infliximab more cost-effective than alternative biologics in fistulizing and moderate-severe luminal CD-although the latter did not reach a willingness-to-pay threshold of <$50,000. In moderate-severe ulcerative colitis, infliximab seems more cost-effective than adalimumab. Multiple tailored approaches to treatment based on objective markers of disease activity or efficacy have been shown to be cost-effective in CD, including following secondary loss of response to anti-TNF therapy for postoperative recurrence and in escalating treatment. For immunomodulator treatment, both thiopurine methyltransferase (TPMT) testing before commencing thiopurines and thiopurine metabolite testing for dose optimization seem cost-effective.

In a win-win for patients and payers, several potential avenues to achieve cost-effectiveness-but also therapeutic optimization of anti-TNF therapies-were elucidated in this review with comparatively sparse data for immunomodulators. Optimizing immunomodulator and anti-tumor necrosis factor alpha therapy to achieve objective disease control seems to be cost-effective at conventional willingness-to-pay thresholds in a number of clinical settings.

No study has evaluated the direct annual costs of inflammatory bowel disease patients treated with anti-tumour necrosis factor therapy.

The purpose of this study was to identify annual direct costs and main cost drivers of anti-tumour necrosis factor-treated inflammatory bowel disease patients.

All inflammatory bowel disease patients treated with infliximab or adalimumab at Nancy University Hospital were consecutively screened for inclusion from November 2016-February 2017. Data about hospitalisation, surgery, medication, outpatient visits, investigations and transport over the previous 12 months were retrospectively collected.

A total of 108 patients (n = 83 Crohn's disease; n = 25 ulcerative colitis) were included. The mean annual cost per patient was €15,775 (standard deviation €7221), with no difference between Crohn's disease and ulcerative colitis (p = 0.2). The main cost driver was medication, which accounted for 84% of the total direct cost. Hospitalisation and surgery represented 11% and 2% of the direct costs. History of switch to another anti-tumour necrosis factor treatment was identified as the only independent predictor of greater direct costs in the multivariate analysis (p = 0.0018).

In a French tertiary referral centre, direct costs of anti-tumour necrosis factor therapy-treated patients were mainly driven by medication, while hospitalisation and surgery represented only a minor part of the costs. There was no difference between Crohn's disease and ulcerative colitis patients.

Therapeutic drug monitoring (TDM) has emerged as a useful tool to optimize the use of drug therapies in adults with inflammatory bowel disease (IBD), including both Crohn's disease (CD) and ulcerative colitis (UC), especially during the use of biological therapies, for which the pharmacokinetics and pharmacodynamics are highly variable among patients. Fewer data exist in children. This review examines the current literature on TDM in pediatric IBD.

Drug clearance is affected by a number of patient and disease factors. For thiopurines, adjusting dosing by monitoring 6-thioguanine (6TGN) and 6-methylmercaptopurine ((6MMP) levels is demonstrated to maximize response and minimize toxicity, while monitoring metabolite levels when treating with anti-tumor necrosis factor (anti-TNF) remain controversial. While in adults the use of TDM in the setting of loss of response to anti-TNF therapy is established, in children, only a small number of studies exist, but these too have encouraging results. There are however, conflicting data regarding the optimal timing of TDM, comparing "reactive" monitoring and "proactive" monitoring. No such data exist in pediatrics. TDM is cost-effective, and dose reduction may represent a safety benefit. There are limited adult data for use of TDM for the newer biologics, vedolizumab and ustekinumab, but early results suggest similarly promising utility. The use of TDM in pediatric IBD is increasing in clinical practice, with similar efficacy to adults demonstrated in children with loss of response to anti-TNF therapy. More prospective studies are needed in children to examine proactive monitoring and utility of TDM with newer biologics.

The development of therapeutic antibodies represents a revolutionary change in medical therapy for digestive diseases. Beginning with the initial studies that confirmed the pathogenicity of cytokines in inflammatory bowel disease, the development and application of therapeutic antibodies brought challenges and insights into their potential and optimal use. Infliximab was the first biological drug approved for use in Crohn's disease and ulcerative colitis. The lessons learned from infliximab include the importance of immunogenicity and the influence of pharmacokinetics on disease response and outcomes. Building on this foundation, other therapeutic antibodies achieved approval for inflammatory bowel disease and many more are in development for several digestive diseases. In this review, we reflect on the history of therapeutic antibodies and discuss current practice and future directions for the field.

Therapeutic drug monitoring (TDM) of anti-TNF is increasingly used to manage inflammatory bowel diseases (IBD) and rheumatoid arthritis (RA). The cost-effectiveness of this strategy is debated.

All studies comparing the cost-effectiveness of a TDM-based strategy and an empirical dose management of anti-TNF in IBD or RA were screened. Studies were identified through the MEDLINE electronic database (up to July 2016), and annual international meeting abstracts were also manually reviewed.

Seven studies were included: two randomized controlled trials (RCTs) enrolling 332 patients [247 Crohn's disease (CD) and 85 ulcerative colitis (UC)] and five modeling approaches. Four studies included only CD patients, one included both CD and UC patients, and two included only RA patients. Three studies compared the cost-effectiveness of the two strategies in patients with secondary infliximab (IFX) failure (dose-escalation strategy), one in patients in remission on optimized IFX (de-escalation strategy), one in patients starting adalimumab, and two in patients with clinical response to maintenance anti-TNF therapy. The two RCTs demonstrated that a TDM strategy led to major cost savings, ranging from 28 to 34 %. The three modeling approaches with regard to CD patients demonstrated cost savings ranging from $5396 over a 1-year period to €13,130 per patient at 5 years of follow-up. A TDM strategy also led to major cost savings in the two modeling approaches in RA patients.

Available evidence indicates that a TDM strategy leads to major cost savings related to anti-TNF therapy in both IBD and RA patients, with no negative impact on efficacy.