Letter: infliximab concentrations during induction therapy-one size does not fit all

Impact of proactive therapeutic drug monitoring of infliximab during the induction phase in IBD patients. A Bayesian approach

BACKGROUND AND OBJECTIVES

there is increasing evidence that proactive therapeutic drug monitoring in induction is useful to improve the control of inflammatory bowel disease (IBD), although it remains controversial. The primary objective of the study was to assess the short-term outcomes of proactive Bayesian therapeutic drug monitoring (TDM) during induction, to optimize infliximab (IFX) maintenance dose.

METHODS

retrospective observational cohort of IBD patients > 18 years. They were divided into two cohorts, standard therapy group (ST-group), with clinically based dose adjustment, and monitoring group (iTDM-group), with pharmacokinetic parameters calculated by Bayesian prediction at week 6 and individualized dosage regimens thereafter. In patients with an infliximab trough level (ITL) at week 6 below the optimal therapeutic range, the dose adjustment was performed at the first maintenance dose.

RESULTS

a total of 153 patients were included, 40 in the iTDM-group. Median ITL at week 6 during the induction period was 12.8 µg/ml (IRQ: 12.7) in this group. Only 16 patients (40.0 %) had ITL ≥ 15 µg/ml. Half of the patients (50.3 %) received intensified maintenance therapy during the study period (57.5 % iTDM vs 47.8 % ST, p = 0.291). The proportion of patients achieving primary response at week 14 was 51.8 %. When comparing the two groups, this proportion was higher in the iTDM group (74.3 % vs 44.2 %, p = 0.002). With regards to the variable "poor clinical outcomes" at week 26, this proportion was lower in the iTDM group (3.3 % iTDM vs 21.1 % ST, p = 0.024).

CONCLUSIONS

proactive therapeutic drug monitoring using Bayesian approach is associated with higher primary response rates and fewer short-term complications.

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.

The effect of aging on infliximab exposure and response in patients with inflammatory bowel diseases

AIMS

Controversies regarding infliximab treatment in elderly patients with inflammatory bowel diseases remain. We evaluated the effect of patient's age on infliximab exposure, efficacy and safety.

METHODS

Retrospective case-control data of patients receiving infliximab induction treatment were analysed. A population pharmacokinetic model was developed to estimate individual pharmacokinetic parameters. A logistic regression model was used to investigate the effect of exposure on endoscopic remission. Repeated time-to-event models were developed to describe the hazard of safety events over time.

RESULTS

A total of 104 patients (46 elderly, ≥65 years) were included. A two-compartment population pharmacokinetic model with linear elimination adequately described the data. Infliximab clearance decreased with older age, higher serum albumin, lower fat-free mass, lower C-reactive protein and absence of immunogenicity. Yet, infliximab exposure was not significantly different between elderly and nonelderly. Regardless of age, an infliximab trough concentration at week (w)14 of 15.6 mg/L was associated with a 50% probability of attaining endoscopic remission between w6 and w22. Infliximab exposure during induction treatment was not a risk factor of (severe) adverse events. The hazard of severe adverse events and malignancy increased by 2% and 7%, respectively, with increasing year of age. Concomitant immunomodulator use increased the hazard of infection by 958%, regardless of age.

CONCLUSIONS

Elderly patients attained infliximab exposure and endoscopic remission similarly to nonelderly patients. Therefore, the same infliximab trough concentration target can be used in therapeutic drug monitoring. The hazards of severe adverse events and malignancy increased with age, but not with infliximab exposure.

Monitoring a Combination of Calprotectin and Infliximab Identifies Patients With Mucosal Healing of Crohn's Disease

BACKGROUND & AIMS

In the TAILORIX trial, no benefit could be shown by infliximab dose escalation based on pharmacokinetic (infliximab serum concentrations) and pharmacodynamic (biomarkers and symptoms) monitoring compared with dose escalation based on symptoms alone in patients with Crohn's disease (CD). We investigated whether integration of pharmacokinetic and pharmacodynamic monitoring can be used to evaluate responses to infliximab induction and maintenance therapy, based on findings from endoscopy.

METHODS

We performed a post hoc analysis of patients with CD included in a trial to test the effects of infliximab dose escalation, based on biomarkers and serum concentrations of infliximab, on symptoms (the Study Investigating Tailored Treatment With Infliximab for Active Crohn's Disease trial; n = 122). We analyzed data from this study to determine whether concentrations of biomarkers and serum concentrations of infliximab were associated with endoscopic outcomes (n = 116). The primary end points were endoscopic response (CD endoscopic index of severity decrease ≥50% from baseline), endoscopic remission (CD endoscopic index of severity, <3), and absence of ulcers at weeks 12 and 54 of infliximab treatment.

RESULTS

Infliximab trough concentrations greater than 23.1 mg/L at week 2 and greater than 10.0 mg/L at week 6 were associated with endoscopic remission at week 12 (positive predictive values, 72% and 76%; negative predictive values, 65% and 59%, respectively). During maintenance therapy, we found evidence for an exposure-response relationship only after dose escalation; trough concentrations greater than 10.6 mg/L were associated with the absence of ulcers at week 54 (positive predictive value, 49%; negative predictive value, 92%). Low fecal concentrations of calprotectin during therapy were associated with endoscopic response and remission (P < .05). Dose escalations increased trough concentrations of infliximab; persistent increase in fecal concentration of calprotectin, despite dose escalation, was associated with a lack of endoscopic response and remission. A significantly higher proportion of patients with antibodies to infliximab, identified by a drug-tolerant assay, dropped out of the study compared with patients without antibodies (P < .0001).

CONCLUSIONS

In a post hoc analysis of data from a trial to test the effects of infliximab dose escalation on symptoms, we found that during maintenance therapy, the combination of fecal concentration of calprotectin and trough concentration of infliximab can guide dose adjustment and increase the chances for endoscopic response and remission. ClinicalTrialsRegister.eu EudraCT no: 2011-003038-14.

Maintenance Adalimumab Concentrations Are Associated with Biochemical, Endoscopic, and Histologic Remission in Inflammatory Bowel Disease

BACKGROUND

A treat-to-target therapeutic approach is emerging as the new standard of care for treating inflammatory bowel disease (IBD), Crohn's disease (CD), and ulcerative colitis (UC).

AIMS

We aimed to investigate the association of serum adalimumab concentrations during maintenance therapy with biochemical, endoscopic, and histologic remission in IBD.

METHODS

This retrospective multicenter study included consecutive IBD patients on adalimumab maintenance therapy who had a C-reactive protein (CRP) within 1 week and/or endoscopic evaluation within 12 weeks of therapeutic drug monitoring between July 2013 and December 2016. Biochemical remission was defined as a normal CRP (≤ 5 mg/L). Endoscopic remission was defined as the absence of any ulceration/erosion or a Rutgeerts score of ≤ i1 for patients with an ileocolonic resection for CD and a Mayo endoscopic score of ≤ 1 for UC. Histologic remission was defined as the absence of any sign of active inflammation. Adalimumab concentrations were measured using the homogeneous mobility shift assay.

RESULTS

Ninety-one CRP levels and 72 colonoscopies from 98 IBD patients [CD: n = 72 (73%)] were evaluated. Based on receiver operating characteristic analyses, we identified an adalimumab concentration threshold of 11.8, 12, and 12.2 μg/mL in CD and 10.5, 16.2, and 16.2 μg/mL in UC to stratify patients with or without biochemical, endoscopic, or histologic remission, respectively. Adalimumab concentrations ≥ 12 μg/mL (OR 8; 95% CI 2-31.9; p = 0.003) and ≥ 12.2 μg/mL (OR 9.6; 95% CI 1.7-56.1; p = 0.012) were independently associated with endoscopic and histologic remission in CD, respectively.

CONCLUSIONS

This study demonstrates that higher maintenance adalimumab concentrations are associated with objective therapeutic outcomes in IBD.