Collecting New Peak and Intermediate Infliximab Levels to Predict Remission in Inflammatory Bowel Diseases

Predictive Model for Outcomes in Inflammatory Bowel Disease Patients Receiving Maintenance Infliximab Therapy

Background

No models predict future outcomes in inflammatory bowel disease (IBD) patients receiving maintenance infliximab therapy. We created a predictive model for unfavorable outcomes.

Methods

Adult patients with IBD receiving maintenance infliximab therapy at 2 centers with matched serum infliximab concentrations and blinded histologic scores (Robarts Histopathologic Index [RHI]) were included. The primary endpoint was an unfavorable outcome of active objective inflammation or need for IBD-related surgery or hospitalization at 6-18 months follow-up. Internal variables were identified using univariable analyses, modeling used multivariable analysis, and performance was assessed (area under receiver-operating curve [AUC]) and externally validated.

Results

In 81 patients, 40.7% developed unfavorable outcomes at follow-up. Infliximab concentration <9.3 µg/mL (odds ratio [OR] 5.3, P = .001) and RHI > 12 (OR 3.4, P = .03) were the only factors associated with developing the primary unfavorable outcome. A prediction score assigning 1 point to each variable had good discrimination and performed similarly on internal (AUC 0.71) and external (AUC 0.73) cohorts. The risk of primary unfavorable outcomes in internal and external cohorts, respectively, was 23% and 15% for a score of 0, 46% and 50% for a score of 1, and 100% and 75% for a score of 2. Infliximab concentration alone performed similar to the 2-predictor model in internal (AUC 0.65, P = .5 vs. 2-predictor model) and external (AUC 0.70, P = .9, vs. 2-predictor model) cohorts.

Conclusions

Using unbiased variable selection, a 2-predictor model using infliximab concentrations and histology identified IBD patients on maintenance infliximab therapy at high risk of future unfavorable outcomes. For practical applicability, infliximab concentrations alone performed similarly well.

Optimising infliximab induction dosing to achieve clinical remission in Chinese patients with Crohn's disease

Aims

A strategy based on therapeutic drug monitoring and population pharmacokinetic (popPK) models would likely increase the rate of clinical remission (CR) after infliximab (IFX) induction in patients with Crohn's disease (CD). This study aimed to evaluate the relationship between early IFX levels and antibodies to infliximab (ATI) and CR at week 14 and simulate the probability of attaining the identified exposure target.

Methods

Patients with CD (n = 140) treated with IFX were enrolled to develop the popPK model. Of these, 43 moderate-to-severe patients with CD were followed up at week 14. Simulations were performed on patients with different dosage regimens and covariates.

Results

IFX levels >20.08 μg/mL at week 2, >18.44 μg/mL at week 6, and >3.08 μg/mL at week 14 were linked to CR. A one-compartment model fit the data best. The covariates influencing clearance were fat free mass, albumin and ATI levels. To achieve IFX levels >20.08 μg/mL at week 2, ≥400 mg IFX was predicted to be required in over 50% patients with 45-70 kg and 35-45 g/L albumin, except for patients with 70 kg and 30 g/L albumin.

Conclusion

IFX levels >20.08 μg/mL at week 2 and absence of ATI at week 14 are associated with CR. Optimising IFX induction dosing will be critical to achieve the target of early IFX levels associated with CR.

Therapeutic drug monitoring in patients with inflammatory bowel disease on ustekinumab

OBJECTIVE

Therapeutic drug monitoring is used clinically to guide anti-tumor necrosis factor (TNF) therapy for inflammatory bowel disease (IBD), but its use for ustekinumab (UST) remains unclear. This study aimed to determine predictive variables of UST levels.

METHODS

In this retrospective cohort of patients with IBD, UST trough levels were drawn at maintenance dosing. Relationships between UST trough levels and demographics, therapy, and outcomes were analyzed. Machine-learning models were used to infer combinatorial traits predictive of UST levels.

RESULTS

Altogether 177 patients with IBD on UST had a mean UST trough level of 4.742 μg/mL. The injection schedule correlated significantly (P < 0.001) with UST levels. Naiveté to anti-TNFs correlated with higher UST levels (P = 0.048). Univariate analysis revealed that higher inflammatory biomarkers significantly correlated to lower UST levels and a lower Simple Endoscopic Score to Crohn's Disease to adequate UST levels (P = 0.018). Multivariate analysis identified body mass index (BMI), previous anti-TNF failure, and laboratory flare as predictors of UST levels with an area under the receiver operating characteristic curve (AUROC) of 0.72. The UST cut-off level of 5.77 μg/mL yielded a 0.79 AUROC, 80% sensitivity, and 81% specificity for predicting endoscopic remission of Crohn's disease. For the clinical remission end-point in ulcerative colitis, UST level of 4.73 μg/mL yielded a 0.69 AUROC, 53% sensitivity, and 86% specificity.

CONCLUSIONS

Higher UST levels correlated with less disease activity. BMI was an important consideration for UST response as well. Therefore, UST dose adjustments to reach target levels may optimize response.

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.

Predictive models assessing the response to ustekinumab highlight the value of therapeutic drug monitoring in Crohn's disease

BACKGROUND

Despite the therapeutic efficacy of Ustekinumab (UST) in Crohn's disease (CD), loss of response (LOR) is observed over time. This study aims to evaluate the impact of the UST pharmacokinetics (PK) at induction on clinical and endoscopic outcomes, as well as to find predictive markers of UST response.

METHODS

This retrospective study included 80 CD patients. Pharmacokinetics data (trough levels (TLs)) combined with clinical and biological parameters were fed into tailored logistic regression and tree-based ensemble techniques to predict clinical and endoscopic outcomes at one year of follow-up.

RESULTS

TLs at week 16 were significantly lower among patients with moderate to severe endoscopic activity during the follow-up (p = 0.04). The best model to predict endoscopic outcome was obtained at week 16 by Random Forest with an area under the receiver operating characteristic curve of 0.92 ± 0.08, sensitivity 91% and specificity 75%, with key inputs such as lymphocyte and monocyte counts at week 8, and UST TLs and CRP at week 16.

CONCLUSIONS

This real-world study confirms the relationship between early UST TLs and both clinical and endoscopic outcomes. Models were developed for the task of predicting clinical and endoscopic remission in CD patients treated with UST, highlighting the clinical relevance of UST TLs at week 16.

Proactive versus Reactive Therapeutic Drug Monitoring: Why, When, and How?

BACKGROUND

Up to a third of inflammatory bowel disease) patients show primary nonresponse to antitumor necrosis factor (anti-TNF) biological therapy, and of those who respond, up to 40% develop secondary loss of response (LOR). Therapeutic drug monitoring (TDM) plays a crucial role in assessing patients with LOR to guide therapy by giving more of the drug or switching to a different biological agent. Although reactive TDM is suggested or recommended by the majority of gastroenterology associations, proactive TDM seems to be more controversial.

SUMMARY

In this article, we discuss the updated guidelines on TDM and will also discuss the available data supporting proactive and reactive TDM in patients with Crohn's disease and those with ulcerative colitis using the different available biological agents.

KEY MESSAGES

Therapeutic drug monitoring (TDM) is a valuable tool to aid in inflammatory bowel disease (IBD) therapy optimization. Reactive TDM is widely accepted in IBD patients with suspected loss of response, especially in those receiving antitumor necrosis factor (anti-TNF) agents. Proactive TDM is emerging as a reasonable approach to patients initiated on anti-TNF therapy, specifically infliximab and, to some extent, adalimumab, particularly for patients with severe ulcerative colitis and fistulizing Crohn's disease. Similarly, TDM may play a role in patients considering de-escalation from combination therapy. To date, proactive TDM is not widely applied to ustekinumab and vedolizumab and more data are required before this becomes part of clinical practice.

Population pharmacokinetics of subcutaneous infliximab CT-P13 in Crohn's disease and ulcerative colitis

BACKGROUND

Infliximab is a chimeric monoclonal antibody against tumour necrosis factor-alpha for the treatment of Crohn's disease (CD) and ulcerative colitis (UC). Recently, a subcutaneous formulation of CT-P13, an infliximab biosimilar, was approved for clinical use.

AIMS

To characterise CT-P13 pharmacokinetics (PK) and its clinically relevant determinants after subcutaneous administration through population PK modelling.

METHODS

Data from a two-part Phase I study with intravenous (5 mg/kg) and variable maintenance subcutaneous dosing of CT-P13 with frequent PK sampling in patients with CD or UC were used. Population PK analysis was conducted by non-linear mixed effects modelling. Covariates affecting PK parameters were chosen based on their clinical relevance (effect size of ≥20%) using a full fixed-effect modelling approach.

RESULTS

CT-P13 PK was described by a two-compartment model with linear elimination. The half-life in a typical 70 kg patient with serum albumin of 44 g/L was 10.8 days. The typical value for clearance was 0.355 L/d, absorption constant 0.273/d, bioavailability 79.1%, central volume of distribution 3.10 L and peripheral volume of distribution 1.93 L. Clinically relevant covariates affecting clearance were body weight (+43.2% from 70 to 120 kg), the presence of anti-drug antibodies (+39%) and serum albumin concentration (+30.1% from 44 to 32 g/L). Simulated drug exposure was comparable between routes of administration for patients weighing 50 or 70 kg, but lower with subcutaneous dosing in patients weighing 120 kg.

CONCLUSIONS

This first population PK model for subcutaneous CT-P13 supports fixed subcutaneous maintenance dosing, although heavy patients had lower cumulative drug exposure.