Therapeutic Drug Monitoring of Biologics in Crohn's Disease

Different infliximab induction dosing regimens do not affect remission rates up to 1 year in children with Crohn's disease

OBJECTIVES

Multiple studies in patients with Crohn's disease (CD) treated with anti-tumor necrosis factor alpha agents have shown that proactive therapeutic drug monitoring (TDM) during the maintenance phase leads to improved outcomes. We aimed to assess whether accelerated infliximab administration during induction resulted in improved outcomes.

METHODS

This retrospective study included CD patients aged 5-17.9 years that were treated with infliximab. We compared outcomes of patients treated during induction with 5-8 mg/kg dosing at Weeks 0, 2, 6, and 14 (Group 1), versus accelerated dosing (≥8 mg/kg and/or >4 infusions until Week 14, Group 2) of infliximab. Primary outcome was steroid-free clinical remission by Week 52.

RESULTS

Sixty-eight patients were included, of whom seven discontinued infliximab before Week 14, due to infusion reactions, immunogenic failure, or primary nonresponse. Comparison of Group 1 (n = 25) and Group 2 (n = 36) showed similar clinical characteristics, as well as inflammatory markers, at infliximab initiation. Despite receiving significantly more infliximab, and reaching a higher trough level by Week 14 (10.3 ± 1.2 vs. 3.3 ± 0.7, p < 0.001), the median Pediatric Crohn's disease Activity Index (PCDAI) was slightly higher in Group 2 versus Group 1 (14 [5-20] vs. 5 [0-15], p = 0.02). However, at Weeks 26 and 52 the PCDAI and inflammatory markers were comparable between the groups. Moreover, about 70% in both groups achieved the desirable trough infliximab levels by Week 52.

CONCLUSION

Accelerated infliximab dosing during induction did not result in improved outcomes up to 12 months follow-up. Prospective studies are required to determine the exact timing in which proactive TDM should be applied.

Biologics, small molecule therapies and surgery in small bowel Crohn's disease

PURPOSE OF REVIEW

The terminal ileum and small bowel (SB) are involved in 30-45% of patients with Crohn's disease, while 20% have both small and large bowel involvement. Ileal Crohn's is associated with higher risk of progression to stricturing and penetrating disease 1 , hence it's imperative to utilize effective therapies to induce and maintain clinical and endoscopic remission and prevent intestinal complications. We review the available data of biologics and upadacitinib in small bowel disease, and the emerging data on the role of surgery as first line therapy for isolated Crohn's ileitis.

RECENT FINDINGS

Most trials assessing drug efficacy do not report efficacy by disease location, and robust data on efficacy of therapies in isolated small bowel Crohn's is sparse. Several studies indicate that small bowel disease is generally less responsive to biologics, and could require higher drug trough levels to achieve endoscopic healing.

SUMMARY

Current therapies for induction and maintenance of remission in moderate to severe Crohn's disease include several classes of monoclonal antibodies and a Janus Kinase inhibitor, upadacitinib. While small bowel Crohn's disease is generally less responsive to treatment, anti-TNFs are still preferred as first line therapy, and the option of early ileocecal resection in early limited ileal disease is gaining interest.

Overview of therapeutic drug monitoring and clinical practice

With the rapid development of clinical pharmacy in China, therapeutic drug monitoring (TDM) has become an essential tool for guiding rational clinical drug use and is widely concerned. TDM is a tool that combines pharmacokinetic and pharmacodynamic knowledge to optimize personalized drug therapy, which can improve treatment outcomes, reduce drug-drug toxicity, and avoid the risk of developing drug resistance. To effectively implement TDM, accurate and sophisticated analytical methods are required. By researching the literature published in recent years, we summarize the types of commonly monitored drugs, therapeutic windows, and clinical assays and track the trends and hot spots of therapeutic drug monitoring. The purpose is to provide guidelines for clinical blood drug concentration monitoring, to implement individualized drug delivery programs better, to ensure the rational use of drugs for patients, and to provide a reference for the group to carry out related topics in the future.

The 2023 Impact of Inflammatory Bowel Disease in Canada: Treatment Landscape

The therapeutic landscape for inflammatory bowel disease (IBD) has changed considerably over the past two decades, owing to the development and widespread penetration of targeted therapies, including biologics and small molecules. While some conventional treatments continue to have an important role in the management of IBD, treatment of IBD is increasingly moving towards targeted therapies given their greater efficacy and safety in comparison to conventional agents. Early introduction of these therapies-particularly in persons with Crohn's disease-combining targeted therapies with traditional anti-metabolite immunomodulators and targeting objective markers of disease activity (in addition to symptoms), have been shown to improve health outcomes and will be increasingly adopted over time. The substantially increased costs associated with targeted therapies has led to a ballooning of healthcare expenditure to treat IBD over the past 15 years. The introduction of less expensive biosimilar anti-tumour necrosis factor therapies may bend this cost curve downwards, potentially allowing for more widespread access to these medications. Newer therapies targeting different inflammatory pathways and complementary and alternative therapies (including novel diets) will continue to shape the IBD treatment landscape. More precise use of a growing number of targeted therapies in the right individuals at the right time will help minimize the development of expensive and disabling complications, which has the potential to further reduce costs and improve outcomes.

Surface plasmon resonance assays for the therapeutic drug monitoring of infliximab indicate clinical relevance of anti-infliximab antibody binding properties

OBJECTIVES

The therapeutic antibody infliximab (IFX) has improved the life quality of numerous autoinflammatory disease patients. However, IFX can trigger the generation of anti-drug antibodies (ADA), whose optimal evaluation and management are currently subject of controversial discussions. We present two novel surface plasmon resonance (SPR) biosensor assays for therapeutic drug monitoring of IFX and characterization of ADA and investigated the diagnostic value of ADA binding properties.

METHODS

IFX and ADA were quantified via developed SPR biosensor assays (IFXmon and ADAmon, respectively) and diagnostics-approved ELISA in sera from inflammatory bowel disease patients. Pre-analytic ADA enrichment with magnetic beads enabled analytical drug tolerance of the ADAmon assay. The dissociation ratio (DissR) as an index for ADA:IFX binding stability was calculated from the SPR sensorgrams of ADA quantification runs.

RESULTS

IFX levels determined by IFXmon assay and ELISA showed high agreement, whereas ADA quantification concordance between ADAmon assay and ELISA was poor. In patients, DissR was predominantly constant over time and differed significantly between therapy outcomes. A DissR cut-off of 1.524 indicated undetectable IFX levels with 71.4% sensitivity and 88.9% specificity. Additionally, the SPR reference surface was exploited as serum-individual negative control to check result plausibility within multi-sample run sequences.

CONCLUSIONS

Overall, both SPR biosensor assays exhibited reliable quantitative performance with accuracies superior to their ELISA counterparts and precision inferior to ELISA only for ADAmon. DissR presented itself as promising ADA binding parameter and could contribute to both earlier and more tailored therapeutic decisions.

Validation Study of Novel Point-of-Care Tests for Infliximab, Adalimumab and C-Reactive Protein in Capillary Blood and Calprotectin in Faeces in an Ambulatory Inflammatory Bowel Disease Care Setting

Background and aims: Point-of-care tests (POCT) allow instant measurement of inflammatory markers and drug concentrations. Here, we studied agreement between a novel POCT device and reference methods of measuring infliximab (IFX) and adalimumab (ADL) serum concentrations and C-reactive protein (CRP) and faecal calprotectin (FCP) concentrations of patients with inflammatory bowel disease (IBD). Methods: In this single-centre validation study, IBD patients were recruited in which IFX, ADL, CRP and/or FCP tests were required. IFX, ADL and CRP POCT were performed on capillary whole blood (CWB), obtained via finger prick. Additionally, IFX POCT was performed on serum samples. FCP POCT was performed on stool samples. Agreement between POCT and reference methods was tested using Passing-Bablok regression, intra-class correlation coefficients (ICC) and Bland-Altman plots. Results: In total, 285 patients participated. Passing-Bablok regression identified differences between the reference method and IFX CWB POCT (intercept = 1.56), IFX serum POCT (intercept = 0.71, slope = 1.10) and ADL CWB POCT (intercept = 1.44). There were also differences in the Passing-Bablok regressions of CRP (intercept = 0.81, slope = 0.78) and FCP (intercept = 51 and slope = 0.46). Bland-Altman plots demonstrated that IFX and ADL concentrations were slightly higher with the POCT and CRP and FCP were slightly lower with POCT. The ICC demonstrated almost perfect agreement with IFX CWB POCT (ICC = 0.85), IFX serum POCT (ICC = 0.96), ADL CWB POCT (ICC = 0.82) and CRP CWB POCT (ICC = 0.91) and moderate agreement with FCP POCT (ICC = 0.55). Conclusions: IFX and ADL results were slightly higher with this novel rapid and user-friendly POCT, whereas CRP and FCP results were slightly lower compared to the reference methods.

90K/Mac-2 BP Is a New Predictive Biomarker of Response to Infliximab Therapy in IBD Patients

Inflammatory bowel diseases (IBD), comprising Crohn's disease (CD) and Ulcerative Colitis (UC), are multifactorial disorders characterized by a chronic inflammatory status with the secretion of cytokines and immune mediators. Biologic drugs targeting pro-inflammatory cytokines, such as infliximab, are broadly used in the treatment of IBD patients, but some patients lose responsiveness after an initial success. The research into new biomarkers is crucial for advancing personalized therapies and monitoring the response to biologics. The aim of this single center, observational study is to analyze the relationship between serum levels of 90K/Mac-2 BP and the response to infliximab, in a cohort of 48 IBD patients (30 CD and 18 UC), enrolled from February 2017 to December 2018. In our IBD cohort, high 90K serum levels were found at baseline in patients who then developed anti-infliximab antibodies at the fifth infusion (22 weeks after the first), becoming non-responders (9.76 ± 4.65 µg/mL compared to 6.53 ± 3.29 µg/mL in responder patients, p = 0.005). This difference was significant in the total cohort and in CD, but not significant in UC. We then analyzed the relationship between serum levels of 90K, C-reactive protein (CRP), and Fecal calprotectin. A significant positive correlation was found at baseline between 90K and CRP, the most common serum inflammation marker (R = 0.42, p = 0.0032). We concluded that circulating 90K could be considered a new non-invasive biomarker for monitoring the response to infliximab. Furthermore, 90K serum level determination, before the first infliximab infusion, in association with other inflammatory markers such as CRP, could assist in the choice of biologics for the treatment of IBD patients, thereby obviating the need for a drug switch due to loss of response, and so improving clinical practice and patient care.

Ustekinumab Promotes Radiological Fistula Healing in Perianal Fistulizing Crohn's Disease: A Retrospective Real-World Analysis

There is insufficient evidence to confirm the efficacy of ustekinumab (UST) in promoting fistula closure in perianal fistulizing Crohn's disease (CD) patients. We aimed to evaluate the efficacy of UST in a real-world setting. The data were retrospectively analyzed. Intestinal clinical and endoscopic changes were evaluated. Fistula radiological outcomes were determined using the Van Assche score. A total of 108 patients were included, 43.5% of whom had complex perianal fistulas. Intestinal clinical and endoscopic remission was achieved in 65.7% and 31.5% of patients, respectively. The fistula clinical remission and response rates were 40.7% and 63.0%, respectively, with a significant reduction in Perianal Crohn's disease Activity Index [5.0(3.0, 8.0) vs. 7.5(5.0, 10.0), p < 0.001] and Crohn's Anal Fistula Quality of Life [23.5(9.3, 38.8) vs. 49.0(32.3, 60.0), p < 0.001]. Radiological healing, partial response, no change, and deterioration were observed in 44.8%, 31.4%, 13.4%, and 10.4% of patients, respectively. The cut-off UST trough concentration for predicting fistula clinical remission was 2.11 μg/mL with an area under the curve of 0.795, a sensitivity of 93.3%, and a specificity of 67.6%. UST is efficacious in promoting radiological fistula closure in patients with perianal fistulizing CD. A UST trough concentration over 2.11 μg/mL was correlated with a higher likelihood of perianal fistula clinical remission.