Pharmacokinetic Features and Presence of Antidrug Antibodies Associate With Response to Infliximab Induction Therapy in Patients With Moderate to Severe Ulcerative Colitis

Population Pharmacokinetic Model for the Use of Intravenous or Subcutaneous Infliximab in Patients with Inflammatory Bowel Disease: Real-World Data from a Prospective Cohort Study

Background/Aims

Infliximab treatment failure in patients with inflammatory bowel disease may result from sub-optimal infliximab trough level. An understanding of pharmacokinetics (PKs) is important to maintain an optimal trough level. PK studies of the switch to subcutaneous (SC) infliximab from intravenous (IV) infliximab using real-world data are lacking. We aimed to develop a population PK model of IV and SC infliximab to predict individual infliximab exposure during maintenance therapy.

Methods

We used data from prospectively collected data on IV and SC infliximab concentrations in patients with inflammatory bowel disease receiving maintenance treatment from February 2020 to December 2022 at Samsung Medical Center. Population PK analysis was conducted by using a two-compartment model with first-order absorption and first-order elimination. Goodness-of-fit plots and visual predictive check were used to evaluate the PK model.

Results

A total of 2,132 samples from 181 patients (149 Crohn's disease and 32 ulcerative colitis) were analyzed. We developed an infliximab population PK model using body mass index, albumin, C-reactive protein level, and the anti-drug antibody level and validated its predictive performance.

Conclusions

It may be possible to predict the infliximab trough level of both IV and SC infliximab in patients with inflammatory bowel disease during maintenance treatment by using our model in real-world practice.

Biologics in the management of pediatric inflammatory bowel disease: When and what to choose

Pediatric inflammatory bowel disease (PIBD) is a chronic inflammatory disorder of the gastrointestinal tract, with rising global incidence and prevalence. Over the past two decades, biologics have added to the therapeutic armamentarium and revolutionized the approach to treatment of inflammatory bowel disease. The available biologics include monoclonal antibodies which target inflammatory cytokines (anti-tumor necrosis factor alpha, anti-interleukin 12/23) or recruitment of leucocytes to the gastrointestinal tract (anti-alpha4beta7 integrin) and small molecules (Janus kinase inhibitors, sphingosine 1-phosphate-inhibitors) which modify the proinflammatory signaling. Considering their potential disease-modifying ability, recent pediatric guidelines from the West have advocated upfront use of biologics in appropriate clinical scenarios as a top-down approach rather than the conventional step-up approach. Although real-world studies are available regarding the clinical efficacy of biologics in PIBD, there is paucity of long-term outcome and safety data in children. Also, little information is available about the best approach in the newly industrialized - developing countries where PIBD is rising but at the same time, infections are prevalent and resources are limited. In this review, we summarize the efficacy and safety profile of biologics and small molecule drugs and discuss the challenges in the management of PIBD, especially in the developing world, and future directions.

Impact of Chronic Inflammatory Diseases on Clinical Pharmacokinetics of Antibody-Based Therapeutic Proteins

Antibody-based therapeutic proteins (TPs) emerged as a promising therapeutic modality for chronic inflammatory diseases. During clinical development, the impact of disease on pharmacokinetics (PK) should be carefully considered to reliably extrapolate PK from healthy volunteers (HVs) in early-phase studies to patients in later-phase studies. This paper aimed to provide an overview of the impact of chronic inflammatory diseases on the PK of antibody-based TPs. A literature search was conducted on Drugs@FDA and PubMed, yielding 30 TPs with author-drawn conclusions about PK differences between HVs and patients with inflammatory diseases. Nine out of 30 TPs suggested PK differences in patients with inflammatory diseases compared with HVs, and patients mostly appeared to have higher drug clearance or lower drug exposure compared with HVs. However, the remaining 21 TPs appeared to have no apparent PK differences between patients and HVs. Based on ratios of reported drug clearance in patients vs. HVs (N: 31 ratios for 22 TPs), the difference in TP clearance due to inflammatory diseases did not exceed twofold (mean clearance ratio: 1.23; standard deviation: 0.25), with the most noticeable difference (>50% higher clearance) observed in patients with inflammatory bowel diseases and rheumatoid arthritis. Covariate assessment in published population PK models of TPs revealed that higher baseline C-reactive proteins and lower baseline albumin levels tend to be correlated with higher TP clearance. Future investigation is necessary to further elucidate the mechanism behind the inflammatory disease-mediated PK differences.

Anti-TNF nonresponse in ulcerative colitis: correcting for mucosal drug exposure reveals distinct cytokine profiles

INTRODUCTION

It remains unclear why up to 30% of ulcerative colitis (UC) patients do not respond to tumor necrosis factor inhibitors (TNFi). Validated biomarkers for nonresponse (N)R) are lacking. Most studies investigating underlying mechanisms do not differentiate between pharmacokinetic and inflammatory mechanisms. We therefore aimed to develop a framework to correct for mucosal drug exposure (MDE) and applied this to mucosal cytokine profiles previously linked to (N)R.

METHODS

In a prospective international cohort, we studied patients with active moderate-severe UC starting TNFi treatment. Patients underwent endoscopy before (baseline) and after induction treatment (follow-up). NR was defined as the absence of Mayo endoscopic subscore improvement by central read or need for colectomy. The ratio of mucosal concentrations of TNFi/TNF was used to define high or low MDE. Mucosal concentrations of interleukin-6 (IL-6), Oncostatin M (OSM), interleukin-10 (IL-10), and interleukin-12/23p40 (IL-12/IL-23p40) were measured.

RESULTS

Fifty-four UC patients were included (43 infliximab, 11 adalimumab) of whom 39 (72%) were endoscopic responders (after a median treatment of 62 days [48-96]). NR with high MDE had high IL-6 at both time points. R with low MDE exhibited low mucosal IL-10 at baseline. At follow-up, high OSM was associated with NR (irrespective of MDE) and high IL-12/IL-23p40 with R.

CONCLUSIONS

We incorporated MDE in mucosal cytokine research to avoid bias due to the insufficient presence of anti-TNF. When applied to mucosal cytokines previously linked to (N)R, IL-6 appears to drive inflammation in TNFi-resistant UC patients, while OSM seems to parallel inflammation and does not cause refractoriness.

Tofacitinib for Hospitalized Acute Severe Ulcerative Colitis Management (The TRIUMPH Study)

Background

Tofacitinib is a rapidly acting Janus kinase (JAK) inhibitor with increasing evidence of effectiveness in patients with acute severe ulcerative colitis (ASUC). However, there are scarce prospective data analyzing the efficacy and rapidity of action in hospitalized ASUC.

Methods

The TRIUMPH study is a prospective open-label interventional trial of tofacitinib in hospitalized patients with ASUC conducted in 5 hospitals across Canada (Clinicaltrials.gov: NCT04925973). Eligible participants included biologic-naïve and experienced patients with ASUC refractory to 3 days of intravenous (IV) corticosteroids (Modified Truelove-Witts Severity Index [MTWSI] > 10 despite steroids). Participants were treated with tofacitinib 10 mg twice daily and assessed daily while in hospital. The primary outcome was day 7 clinical response (MTWSI reduction of > 3 from baseline and ≤ 10).

Results

Among 24 subjects, 33.3% (8/24) had previous anti-TNF failure. Day 7 clinical response was achieved in 58.3% (14/24). The mean number of days to achieve clinical response was 2.4 (SD 1.3). Marked reduction in C-reactive protein was observed in responders within the first two days after tofacitinib initiation compared to nonresponders. Colectomy occurred in 25% (6/24) by 6 months, with no additional colectomy beyond this time point. Five participants reported a total of 13 adverse events.

Conclusions

Tofacitinib is an effective rescue therapy in hospitalized patients with steroid-refractory ASUC. Randomized controlled trials are warranted to compare JAK inhibitors with other rescue therapies, including infliximab in steroid-refractory ASUC (Clinicaltrials.gov: NCT04925973).

Early monitoring of anti-infliximab antibodies by drug-tolerant assay predicts later immunogenicity and drug survival in rheumatic diseases

OBJECTIVES

To investigate the appearance of anti-drug antibodies (ADA) against infliximab (IFX) determined by drug-sensitive and drug-tolerant assays and their relationship with drug levels and drug survival.

METHODS

This longitudinal observational study included 45 patients with RA and 61 with SpA. Serum samples were obtained at weeks 2, 6, 12, 24 and 52. Serum IFX levels were measured by a capture ELISA and ADA by an in-house drug-sensitive two-site (bridging) ELISA (bELISA) and a commercially available drug-tolerant ELISA (IDK, Immundiagnostik, Germany).

RESULTS

ADA were detected earlier by IDK than by bELISA. Once ADA appeared, positivity persisted throughout the study period. Patients who were bELISA ADA+ had higher IDK ADA levels (than bELISA ADA- patients). Circulating IFX levels were detected in all patients except those found to be bELISA ADA+. Serum IFX levels were lower in IDK ADA+ than in IDK ADA- patients. Most patients (64%) discontinued due to inefficacy. The early onset of immunogenicity was related to IFX survival. In both RA and SpA, the median survival (years) was shorter in patients with earlier development of ADA (IDK+ before or at week 24) than those who became IDK+ later (after week 24) or never developed ADA.

CONCLUSION

A drug-tolerant assay detects ADA during IFX therapy earlier and more frequently than a drug-sensitive assay. The onset of immunogenicity detected by drug-tolerant assays is related to the subsequent detection of ADA by drug-sensitive assays and drug survival.

Steroid-Refractory Acute Severe Ulcerative Colitis in Infliximab-Experienced Patients

Acute severe ulcerative colitis (ASUC) is a potentially life-threatening complication of ulcerative colitis (UC) that can lead to significant morbidity and mortality, with a substantial number of patients needing colectomy. Infliximab (IFX) has been increasingly used as a rescue therapy for patients who have failed intravenous steroids and has been more frequently used as an induction and maintenance therapy in moderate-to-severe UC. Therefore, the number of patients admitted with ASUC previously exposed to IFX has been increasing, raising additional challenges in the medical management of these patients to avoid emergent colectomy. This narrative review intends to summarise the most recent evidence in the medical management of steroid-refractory ASUC patients previously exposed to IFX and to propose a treatment algorithm for approaching this difficult-to-treat group of patients.

Therapeutic drug monitoring in inflammatory bowel disease: recent developments

INTRODUCTION

Therapeutic Drug Monitoring (TDM) has an important role in the management of inflammatory bowel disease (IBD) patients on infliximab (IFX) or adalimumab and is recommended in IBD patients presenting a loss of response under anti TNF agent. But, TDM was not recommended for others biotherapies.

AREAS COVERED

Analyzing all publications about TDM and biologics in IBD patients, we reported the major results for each biotherapy.

EXPERT OPINION

Emerging data suggest that TDM will probably be similarly useful forIFX SC. In contrast, there is no demonstrated clinical benefit to the use of TDM with golimumab. For vedolizumab results for the use of both reactive and proactive TDM are discordant. For ustekinumab, data supports the existence of an exposure response relationship, albeit of a lesser magnitude than with anti-TNF agents. Finally, recent data from small case series suggests that TDM could be valuable in optimizing anti-IL23 agents, particularly risankizumab, but this requires further clarification. Consistent with the new concept of 'proactive' strategy, recent data support the utility of dashboard-driven model informed precision dosing (MIDP) of anti-TNF agents, in particular infliximab. Dashboards are software systems using Bayesian population pharmacokinetic modelling to individualize recommendations for target drug levels.

What are the benefits of therapeutic drug monitoring in the optimization of adalimumab therapy? a systematic review and meta-analysis up to 2022

Aims

Persistent uncertainties exist surrounding the therapeutic drug monitoring (TDM) of adalimumab in clinical settings. To address these issues, we conducted a systematic review to assess the current evidence regarding the benefits of TDM for adalimumab.

Methods

PubMed, EMBASE, and Cochrane Databases were searched from inception to October 2022. The trials regarding to the list three key questions were considered: 1) Could routine proactive TDM assist in improving outcomes in patients receiving adalimumab? 2) Could reactive TDM assist in guiding subsequent treatment strategies for patients with treatment failure to adalimumab? 3) Could TDM assist in informing dose reduction or discontinuation in patients with low disease activity or in remission treated with adalimumab? Two reviewers independently selected the studies and extracted the data. Meta-analysis was performed to calculate the relative risk (RR) and 95% confidence interval (CI).

Results

A total of 9 studies was included in this review. For proactive TDM, meta-analysis indicated that proactive TDM (n = 163/257, 63.42%) showed no significant superiority over reactive TDM and/or conventional management (n = 336/606, 55.44%) in achieving and/or maintaining clinical remission by random effects model (RR: 1.24, 95% CI 0.98-1.58, I 2 = 73%). There were three studies that supporting the reactive TDM, low drug levels in the absence of anti-drug antibodies (ADA) strongly indicate the need for dose intensification, and infliximab is a feasible choice for patients with low drug levels and ADA positivity. While swapping to another class should be considered in patients with adequate drug levels. In addition, TDM can help clinicians optimize dosing schedules and prevent overtreatment in patients who have achieved low disease activity and sufficient drug concentrations, with no predictive value for successful adalimumab discontinuation.

Conclusion

Current evidence suggests that proactive TDM is numerically but not statistically significant superiority over reactive TDM and/or conventional management. Reactive TDM can aid in understanding treatment failure and developing subsequent therapy. For patients reaching low disease activity and remission, TDM can help successful dose reduction, while it cannot inform the successful drug discontinuation. However, existing trials are limited, and more well-designed trials are necessary to clarify the role of TDM in adalimumab treatment.

Best Practice for Therapeutic Drug Monitoring of Infliximab: Position Statement from the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

BACKGROUND

Infliximab, an anti-tumor necrosis factor monoclonal antibody, has revolutionized the pharmacological management of immune-mediated inflammatory diseases (IMIDs). This position statement critically reviews and examines existing data on therapeutic drug monitoring (TDM) of infliximab in patients with IMIDs. It provides a practical guide on implementing TDM in current clinical practices and outlines priority areas for future research.

METHODS

The endorsing TDM of Biologics and Pharmacometrics Committees of the International Association of TDM and Clinical Toxicology collaborated to create this position statement.

RESULTS

Accumulating data support the evidence for TDM of infliximab in the treatment of inflammatory bowel diseases, with limited investigation in other IMIDs. A universal approach to TDM may not fully realize the benefits of improving therapeutic outcomes. Patients at risk for increased infliximab clearance, particularly with a proactive strategy, stand to gain the most from TDM. Personalized exposure targets based on therapeutic goals, patient phenotype, and infliximab administration route are recommended. Rapid assays and home sampling strategies offer flexibility for point-of-care TDM. Ongoing studies on model-informed precision dosing in inflammatory bowel disease will help assess the additional value of precision dosing software tools. Patient education and empowerment, and electronic health record-integrated TDM solutions will facilitate routine TDM implementation. Although optimization of therapeutic effectiveness is a primary focus, the cost-reducing potential of TDM also merits consideration.

CONCLUSIONS

Successful implementation of TDM for infliximab necessitates interdisciplinary collaboration among clinicians, hospital pharmacists, and (quantitative) clinical pharmacologists to ensure an efficient research trajectory.

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.

Attitudes, perceptions and barriers in implementing therapeutic drug monitoring for anti-TNFs in inflammatory bowel disease: a survey from the Middle East

BACKGROUND

A growing body of evidence underscores the beneficial impact of therapeutic drug monitoring (TDM) on the efficacy and cost-effectiveness of anti-tumour necrosis factor (TNF) therapy in patients with inflammatory bowel disease (IBD).

OBJECTIVES

We surveyed clinician attitudes, perceptions and barriers related to TDM in IBD in the Middle East.

DESIGN

A 15-question survey was distributed through national gastroenterological societies in five Middle Eastern countries (UAE, Saudi Arabia, Kuwait, Lebanon and Egypt).

METHODS

Data on clinician characteristics, demographics, utilization patterns and obstacles related to the adoption of TDM with anti-TNFs were gathered. Logistic regression analysis was used to predict factors influencing the utilization of TDM.

RESULTS

Among 211 respondents (82% male), 82% were consultants, 8% were physicians with an interest in gastroenterology (GI), and 6% were GI trainees. Of these, 152 met inclusion criteria, treating >5 IBD patients per month and ⩾1 with an anti-TNF per month. TDM was used in clinical practice by 78% (95% CI: 71-85) of respondents. TDM was utilized following the loss of response (LOR) in 93%, for primary non-response (PNR) in 40% and before restarting anti-TNF therapy after a drug holiday in 33% of respondents, while 34% used TDM proactively. No specific factors were associated with the use of TDM. Barriers to TDM use included cost (85%), time lag to results (71%) and lack of insurance reimbursement (65%). Overall knowledge of TDM (70%), interpretation and actioning of results (76%) or awareness of clinical guidelines (57%) were not perceived as barriers. If barriers were removed, 95% would use TDM more frequently; 93% for LOR, 60% for PNR, 50% when restarting after a drug holiday, and 54% would use TDM proactively.

CONCLUSION

Most gastroenterologists use TDM for LOR, with cost, time lag and insurance reimbursement being significant barriers. Addressing these barriers would increase the judicious use of reactive and proactive TDM to optimize anti-TNF therapy in IBD.

Performance of a New Rapid Point-of-Care Test for Infliximab Levels in Patients with Inflammatory Bowel Disease: A Comparison to ELISA

BACKGROUND

Therapeutic drug monitoring of infliximab levels in patients with inflammatory bowel disease (IBD) optimizes patients' treatment. The reference technique is based on enzyme-linked immunosorbent assay (ELISA) although point of care (POC) assays are being developed.

AIMS

To assess the performance of a new rapid immunochromatographic POC assay (Promonitor Quick IFX) compared with ELISA technique to measure infliximab levels in patients with IBD.

METHODS

A prospective, observational, unicentric study was performed on capillary blood samples from patients with IBD before infliximab infusion (trough levels). Infliximab levels and anti-infliximab antibodies were measured using the ELISA technique (Promonitor IFX) and the POC assay. Correlation between both techniques was assessed by Pearson's coefficient. Quantitative differences were evaluated by Bland-Altman analysis. Samples were stratified according to infliximab therapeutic ranges (< 3 μg/mL, 3-8 μg/mL, and > 8 μg/mL).

RESULTS

A total of 135 experimental samples were assessed. Infliximab levels showed a high correlation between POC and ELISA tests (r = 0.84, P < 0.001). The mean difference between tests was 1.46 μg/mL (P < 0.001), being minimal for concentrations < 8 μg/mL. POC and ELISA assays showed an overall concordance of 87.4%. Most samples were in the same therapeutic range, which lead to equivalent therapeutic decisions. POC and ELISA assays detected the presence of anti-infliximab antibodies in 2.2% and 3.7% of the samples, respectively.

CONCLUSIONS

POC assay results in blood samples from patients with IBD were comparable to those obtained with the reference ELISA technique. The POC assay could be considered for routine testing based on its ease of use and rapidity.

Predictors and optimal management of tumor necrosis factor antagonist nonresponse in inflammatory bowel disease: A literature review

Tumor necrosis factor-α (TNF-α) antagonists, the first biologics approved for treating patients with inflammatory bowel disease (IBD), are effective for the induction and maintenance of remission and significantly improving prognosis. However, up to one-third of treated patients show primary nonresponse (PNR) to anti-TNF-α therapies, and 23%-50% of IBD patients experience loss of response (LOR) to these biologics during subsequent treatment. There is still no recognized predictor for evaluating the efficacy of anti-TNF drugs. This review summarizes the existing predictors of PNR and LOR to anti-TNF in IBD patients. Most predictors remain controversial, and only previous surgical history, disease manifestations, drug concentrations, antidrug antibodies, serum albumin, some biologic markers, and some genetic markers may be potentially predictive. In addition, we also discuss the next steps of treatment for patients with PNR or LOR to TNF antagonists. Therapeutic drug monitoring plays an important role in treatment selection. Dose escalation, combination therapy, switching to a different anti-TNF drug, or switching to a biologic with a different mechanism of action can be selected based on the concentration of the drug and/or antidrug antibodies.

Treatment of inflammatory bowel disease-Asian perspectives: the results of a multinational web-based survey in the 8th Asian Organization for Crohn's and Colitis meeting

BACKGROUND/AIMS

As the characteristics of inflammatory bowel disease (IBD) differ between Asians and Westerners, it is necessary to determine adequate therapeutic strategy for Asian IBD patients. We evaluated the current treatment of IBD in Asian countries/regions using a web-based survey.

METHODS

The Korean Association for the Study of Intestinal Diseases conducted a multinational web-based survey for current IBD care in Asia between September 16, 2020, and November 13, 2020.

RESULTS

A total of 384 doctors treating IBD patients from 24 Asian countries/regions responded to the survey. Anti-tumor necrosis factor (TNF) agents, anti-integrins, and anti-interleukin-12/23 agents were available for use by 93.8%, 72.1%, and 70.1% of respondents in Asian countries/regions. Compared with a previous survey performed in 2014, an increased tendency for treatment with biologics, including anti-TNF agents, was observed. In the treatment of corticosteroid-refractory acute severe ulcerative colitis, 72.1% of respondents chose anti-TNF agents, followed by tacrolimus (11.7%). In the treatment of corticosteroid-refractory Crohn's disease, 90.4% chose anti-TNF agents, followed by thiopurines (53.1%), anti-interleukin-12/23 agents (39.3%), and anti-integrin agents (35.7%). In the treatment of Crohn's disease patients refractory to anti-TNF agents, the most preferred strategy was to measure serum levels of anti-TNF and anti-drug antibodies (40.9%), followed by empiric dose escalation or shortening of dosing intervals (25.3%).

CONCLUSIONS

Although there were some differences, treatment strategies for patients with IBD were mostly similar among Asian doctors. Based on the therapeutic outcomes, it is necessary to identify the most appropriate therapeutic strategy for Asian IBD patients.

Comparison of the Pharmacokinetics of CT-P13 Between Crohn's Disease and Ulcerative Colitis

BACKGROUND

We aimed to compare trough infliximab levels and the development of antidrug antibody (ADA) for 1 year between Crohn's disease (CD) and ulcerative colitis (UC) patients who were biologic-naive, and to evaluate their impact on clinical outcomes.

METHODS

This was a prospective, multicenter, observational study. Biologic-naive patients with moderate to severe CD or UC who started CT-P13, an infliximab biosimilar, therapy were enrolled. Trough drug and ADA levels were measured periodically for 1 year after CT-P13 initiation.

RESULTS

A total of 267 patients who received CT-P13 treatment were included (CD 168, UC 99). The rates of clinical remission (72% vs. 32.3%, P <0.001) at week 54 were significantly higher in CD than in UC. The median trough drug level (μg/mL) was significantly higher in CD than in UC up to week 14 (week 2, 18.7 vs. 14.7, P <0.001; week 6, 12.5 vs. 8.6, P <0.001; week 14, 3.4 vs. 2.5, P =0.001). The median ADA level (AU/mL) was significantly lower in CD than in UC at week 2 (6.3 vs. 6.5, P =0.046), week 30 (7.9 vs. 11.8, P =0.007), and week 54 (9.3 vs. 12.3, P =0.032). Development of ADA at week 2 [adjusted odds ratio (aOR)=0.15, P =0.026], initial C-reactive protein level (aOR=0.87, P =0.032), and CD over UC (aOR=1.92, P <0.001) were independent predictors of clinical remission at week 54.

CONCLUSION

Infliximab shows more favorable pharmacokinetics, including high drug trough and low ADA levels, in CD than in UC, which might result in better clinical outcomes for 1-year infliximab treatment in CD patients.

The Role of Low-Dose Oral Methotrexate in Increasing Anti-TNF Drug Levels and Reducing Immunogenicity in IBD

Concomitant immunomodulation is utilised in combination with anti-TNF therapy for IBD primarily to increase drug levels and prevent anti-drug antibody formation. Whilst thiopurines have traditionally been the immunomodulator of choice in IBD populations, there are concerns regarding the long-term safety of the prolonged use of these agents: particularly an association with lymphoproliferative disorders. Given this, we have explored the existing literature on the use of low-dose oral methotrexate as an alternative immunomodulator for this indication. Although there is a lack of data directly comparing the efficacies of methotrexate and thiopurines as concomitant immunomodulators, the available literature supports the use of methotrexate in improving the pharmacokinetics of anti-TNF agents. Furthermore, low-dose oral methotrexate regimens appear to have comparable efficacies to higher-dose parenteral administration and are better tolerated. We suggest that clinicians should consider the use of low-dose oral methotrexate as an alternative to thiopurines when the primary purpose of concomitant immunomodulation is to improve anti-TNF pharmacokinetics.

Therapeutic Drug Monitoring of Infliximab in Acute Severe Ulcerative Colitis

Therapeutic drug monitoring (TDM) is a useful strategy in ulcerative colitis (UC). Nearly a quarter of UC patients will experience acute severe UC (ASUC) in their lifetime, including 30% who will fail first-line corticosteroid therapy. Steroid-refractory ASUC patients require salvage therapy with infliximab, cyclosporine, or colectomy. Fewer data are available for the use of TDM of infliximab in ASUC. The pharmacokinetics of ASUC make TDM in this population more complex. High inflammatory burden is associated with increased infliximab clearance, which is associated with lower infliximab drug concentrations. Observational data support the association between increased serum infliximab concentrations, lower clearance, and favorable clinical and endoscopic outcomes, as well as decreased rates of colectomy. Data regarding the benefit of accelerated or intensified dosing strategies of infliximab-as well as target drug concentration thresholds-in ASUC patients remain more equivocal, though limited by their observational nature. Studies are underway to further evaluate optimal dosing and TDM targets in this population. This review examines the evidence for TDM in patients with ASUC, with a focus on infliximab.

A Systematic Review on the Interest of Drug-tolerant Assay in the Monitoring of Inflammatory Bowel Disease

Many patients with inflammatory bowel disease [IBD] are treated with anti-tumour necrosis factor [TNF] therapies, of which infliximab [IFX] is most commonly used. Loss of response [LOR] to anti-TNF therapy due to immunogenic failure accounts for 20% of subsequent medical intervention and is defined, using a drug-sensitive assay, as low or undetectable concentration of drug with high titres of anti-drug antibodies [ADAb]. We performed a systematic review to investigate the use of a drug-tolerant assay during both induction and maintenance, to monitor patients treated with anti-TNFs. After the search on PubMed, 90 publications were reviewed. Most ADAb detection methods are drug-sensitive, cannot detect ADAb in the presence of drug, and therefore cannot be used close to drug administration when the drug concentration is too high. To overcome this major limitation, several drug-tolerant techniques have been developed and will be discussed in this review. Using drug-tolerant assays, ADAb against IFX or adalimumab [ADM] can be detected during induction and predict primary non-response or LOR. Drug-sensitive assays do not allow detection of ADAb during the induction phase when IFX or ADM concentration is typically high.

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.

Korean clinical practice guidelines on biologics and small molecules for moderate-to-severe ulcerative colitis

Ulcerative colitis (UC), a relapsing-remitting chronic inflammatory bowel disease (IBD), has a variable natural course but potentially severe disease course. Since the development of anti-tumor necrosis factor (TNF) agents has changed the natural disease course of moderate-to-severe UC, therapeutic options for patients who failed conventional treatments are expanding rapidly. IBD clinical trials have demonstrated the potential efficacy and safety of novel biologics such as anti-integrin α4β7 and anti-interleukin-12/23 monoclonal antibodies and small molecules such as a Janus kinase inhibitor. Anti-TNF biosimilars also have been approved and are widely used in IBD patients. Wise drug choices should be made considering evidence-based efficacy and safety. However, the best position of these drugs remains several questions, with limited data from direct comparative trials. In addition, there are still concerns to be elucidated on the effect of therapeutic drug monitoring and combination therapy with immunomodulators. The appropriate treatment regimens in acute severe UC and the risk of perioperative use of biologics are unclear. As novel biologics and small molecules have been approved in Korea, we present the Korean guidelines for medical management of adult outpatients with moderate-to-severe UC and adult hospitalized patients with acute severe UC, focusing on biologics and small molecules.

Combination therapy in inflammatory bowel disease: Current evidence and perspectives

BACKGROUND AND OBJECTIVE

Inflammatory Bowel Diseases (IBD) are chronic nonspecific intestinal inflammatory diseases with a relapsing-remitting course, including Ulcerative Colitis (UC) and Crohn's Disease (CD). Combination therapy has been proposed as a strategy to enhance treatment efficacy in IBD. The aim of this study is to summarize current evidence and perspectives on combination therapies in IBD.

METHODS

Electronic databases such as PubMed, Ovid Embase, Medline, and Cochrane CENTRAL were searched to identify relevant studies.

RESULTS

Current evidence supports that the combination of infliximab and thiopurines is more effective than monotherapy in inducing and maintaining remission in IBD. Data on the combination of other biological agents such as adalimumab, vedolizumab, ustekinumab, and immunosuppressors is lacking or showed conflicting results. Vedolizumab seems a potentially effective maintenance regimen after calcineurin inhibitors-based rescue therapy in acute severe ulcerative colitis (ASUC). Dual Targeted Therapy, which is the combination of two biological agents and/or small molecules, might be a reasonable choice in patients with concomitant IBD and extraintestinal manifestations, or in patients with medical-refractory IBD who lack valid alternatives. Some safety concerns such as adverse events (serious and opportunistic infections) and malignancies (lymphoma and nonmelanoma skin cancer) were raised in combination therapies.

CONCLUSIONS

Combination therapies seem to be effective in some IBD patients such as refractory IBD patients or patients with extraintestinal manifestations, but it might be associated with an increased risk of adverse events and malignancies.

Therapeutic Drug Monitoring in Practice for Inflammatory Bowel Disease

PURPOSE OF REVIEW

To outline the development, rationale, and practical use of therapeutic drug monitoring in patients with inflammatory bowel disease.

RECENT FINDINGS

Therapeutic drug monitoring is traditionally discussed in terms of a proactive or reactive approach. However, these terms are not always consistently defined and can be confusing when translating research to clinical practice. Personalized approaches incorporating clinical context and precision medicine are emerging. Personalized therapeutic drug monitoring combines a structured and proactive strategy for monitoring biologic concentrations as well as identification of antidrug antibody development or subtherapeutic dosing in the setting of loss of response. Optimizing biologic therapy can improve outcomes and avoid loss of response. Why, when, and how we measure drug troughs and anti-drug antibodies is a moving target, though what is known is that the appropriate and evidence-based use of this practice prevents adverse events and improves outcomes in patients with inflammatory bowel disease.

Multi‐model averaging improves the performance of model‐guided infliximab dosing in patients with inflammatory bowel diseases

Infliximab dosage de‐escalation without prior knowledge of drug concentrations may put patients at risk for underexposure and trigger the loss of response. A single‐model approach for model‐informed precision dosing during infliximab maintenance therapy has proven its clinical benefit in patients with inflammatory bowel diseases. We evaluated the predictive performances of two multi‐model approaches, a model selection algorithm and a model averaging algorithm, using 18 published population pharmacokinetic models of infliximab for guiding dosage de‐escalation. Data of 54 patients with Crohn’s disease and ulcerative colitis who underwent infliximab dosage de‐escalation after an earlier escalation were used. A priori prediction (based solely on covariate data) and maximum a posteriori prediction (based on covariate data and trough concentrations) were compared using accuracy and precision metrics and the classification accuracy at the trough concentration target of 5.0 mg/L. A priori prediction was inaccurate and imprecise, with the lowest classification accuracies irrespective of the approach (median 59%, interquartile range 59%–63%). Using the maximum a posteriori prediction, the model averaging algorithm had systematically better predictive performance than the model selection algorithm or the single‐model approach with any model, regardless of the number of concentration data. Only a single trough concentration (preferably at the point of care) sufficed for accurate and precise prediction. Predictive performance of both single‐ and multi‐model approaches was robust to the lack of covariate data. Model averaging using four models demonstrated similar predictive performance with a five‐fold shorter computation time. This model averaging algorithm was implemented in the TDMx software tool to guide infliximab dosage de‐escalation in the forthcoming prospective MODIFI study (NCT04982172).

Magnesium-A Potential Key Player in Inflammatory Bowel Diseases?

The altered magnesium status in inflammatory bowel disease (IBD) patients may have a significant clinical imprint considering its role in cell signaling and genomic stability, as well as its involvement in IBD patients' fatigue. Our study pioneers the investigation of magnesium hair concentration patterns in an adult population of IBD patients. The hair magnesium concentration in IBD patients is compared to healthy controls in order to identify correlations between the magnesium status and relevant parameters related to disease activity, psychological status, and sleep quality. We report a significantly lower hair magnesium concentration within the IBD group compared to healthy controls (95%CI: 0.006-0.062; p = 0.017) and lower levels in CD compared to UC (95%CI: -0.061--0.002; p = 0.038). We identified a borderline statistical significance between the hair magnesium concentration and UC disease activity (95%CI; -0.679-0.008; p = 0.055) and a significantly lower magnesium concentration in patients who reported increased sleep latency (95%CI -0.65--0.102; p = 0.011) or decreased sleep duration (95%CI -0.613--0.041; p = 0.028). Our results advance several hypotheses with substantial clinical impact to be confirmed in future studies. Magnesium levels appear to be modified in IBD patients, which suggests it either plays a primary role in disease pathophysiology or a is result of the disease's evolution. Magnesium could be used in predictive models for clinical/subclinical disease activity. Moreover, magnesium supplementation may improve IBD evolution and sleep quality for patients with a deficit of this mineral. However, confirmatory evidence-based studies are needed to generate specific dosing, time of supplementation, and optimum monitoring of magnesium status in IBD patients.

Early improvement in bowel wall thickness on transperineal ultrasonography predicts treatment success in active ulcerative colitis

BACKGROUND

Bowel ultrasonography is a non-invasive imaging tool that can repeatedly monitor ulcerative colitis (UC) activity.

AIM

This study aimed to determine whether early transabdominal or transperineal ultrasonography changes can predict subsequent clinical response to induction therapy in patients with UC.

METHODS

This single-centre prospective study explored ultrasonographic predictors for clinical remission (patient-reported outcome-2 ≤ 1 with no rectal bleeding subscore) at week 8 in patients with active UC who underwent induction therapy, in comparison with faecal calprotectin and C-reactive protein (measured at baseline, week 1 and week 8). Predictive factors were assessed using multivariable regression models and receiver-operating-characteristic curve analysis.

RESULTS

A total of 100 patients were analysed, of which 54 achieved remission at week 8. Baseline biomarker and ultrasonographic-parameter values were not predictive of remission. Contrastingly, change from baseline to week 1 in rectal bowel wall thickness measured using transperineal ultrasonography was an independent predictor of remission by week 8 (adjusted odds ratio is associated with a 1-mm decrease: 1.90 [95% confidence interval, 1.22-2.95]). In a subgroup analysis of the patients who did not achieve remission in 1 week, the predictive value of change in rectal bowel wall thickness remained high (AUC = 0.77 [95% confidence interval, 0.61-0.88]).

CONCLUSION

Improvement in rectal bowel wall thickness measured using transperineal ultrasonography at week 1 predicts treatment success and potentially facilitates decision making during the early course of induction therapy in UC.

Optimizing Therapies Using Therapeutic Drug Monitoring: Current Strategies and Future Perspectives

Therapeutic drug monitoring (TDM) has emerged as a strategy for treatment optimization in inflammatory bowel diseases to maximize benefit and to reach more stringent, objective end points. Optimal drug concentrations in inflammatory bowel disease vary according to treatment target, disease phenotype, inflammatory burden, and timing of sampling during the treatment cycle. This review provides an update on TDM with biologic and oral small molecules, evaluates the role of reactive vs proactive TDM, and identifies the gaps in current evidence. In the future, adaptations to how we use TDM may contribute further to the goal of personalized treatment in patients with IBD.

Therapeutic drug monitoring for biological medications in inflammatory bowel disease

Therapeutic drug monitoring (TDM) is the measurement of serum drug concentrations and anti-drug-antibodies (ADA) for biologic therapies used to treat inflammatory bowel disease (IBD). The aim of this article is to review the current literature concerning reactive and proactive TDM for both adults and children with IBD. Although optimal trough concentration windows for some of these medications are not well defined, there is mounting evidence to suggest that reactive TDM is associated with favorable therapeutic outcomes, including less immunogenicity, greater drug exposure, and a decreased risk of treatment failure. Moreover, while the exact mechanism of loss of response is not fully elucidated, the vast majority of studies have reported a decreased incidence of nonresponse and secondary loss of response when TDM is implemented. Proactive TDM, while even less understood in the literature, employs a schedule of preemptive analysis of serum trough concentrations to accordingly adjust the patient's biologic dosage. Proactive TDM may decrease the need for IBD-related surgery/hospitalization, and therefore merits future studies of investigation.

Cytotoxicity of Thiopurine Drugs in Patients with Inflammatory Bowel Disease

The effectiveness of thiopurine drugs in inflammatory bowel disease (IBD) was confirmed more than a half-century ago. It was proven that these can be essential immunomodulatory medications. Since then, they have been used routinely to maintain remission of Crohn’s disease (CD) and ulcerative colitis (UC). The cytotoxic properties of thiopurines and the numerous adverse effects of the treatment are controversial. However, the research subject of their pharmacology, therapy monitoring, and the search for predictive markers are still very relevant. In this article, we provide an overview of the current knowledge and findings in the field of thiopurines in IBD, focusing on the aspect of their cytotoxicity. Due to thiopurines’ benefits in IBD therapy, it is expected that they will still constitute an essential part of the CD and UC treatment algorithm. More studies are still required on the modulation of the action of thiopurines in combination therapy and their interaction with the gut microbiota.

Artificial Neural Network Analysis-Based Immune-Related Signatures of Primary Non-Response to Infliximab in Patients With Ulcerative Colitis

Infliximab (IFX) is an effective medication for ulcerative colitis (UC) patients. However, one-third of UC patients show primary non-response (PNR) to IFX. Our study analyzed three Gene Expression Omnibus (GEO) datasets and used the RobustRankAggreg (RRA) algorithm to assist in identifying differentially expressed genes (DEGs) between IFX responders and non-responders. Then, an artificial intelligence (AI) technology, artificial neural network (ANN) analysis, was applied to validate the predictive value of the selected genes. The results showed that the combination of CDX2, CHP2, HSD11B2, RANK, NOX4, and VDR is a good predictor of patients' response to IFX therapy. The range of repeated overall area under the receiver-operating characteristic curve (AUC) was 0.850 ± 0.103. Moreover, we used an independent GEO dataset to further verify the value of the six DEGs in predicting PNR to IFX, which has a range of overall AUC of 0.759 ± 0.065. Since protein detection did not require fresh tissue and can avoid multiple biopsies, our study tried to discover whether the key information, analyzed by RNA levels, is suitable for protein detection. Therefore, immunohistochemistry (IHC) staining of colonic biopsy tissues from UC patients treated with IFX and a receiver-operating characteristic (ROC) analysis were used to further explore the clinical application value of the six DEGs at the protein level. The IHC staining of colon tissues from UC patients confirmed that VDR and RANK are significantly associated with IFX efficacy. Total IHC scores lower than 5 for VDR and lower than 7 for RANK had an AUC of 0.828 (95% CI: 0.665-0.991, p = 0.013) in predicting PNR to IFX. Collectively, we identified a predictive RNA model for PNR to IFX and explored an immune-related protein model based on the RNA model, including VDR and RANK, as a predictor of IFX non-response, and determined the cutoff value. The result showed a connection between the RNA and protein model, and both two models were available. However, the composite signature of VDR and RANK is more conducive to clinical application, which could be used to guide the preselection of patients who might benefit from pharmacological treatment in the future.

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

BACKGROUND

The loss of response to infliximab is a challenge for clinicians in the management of inflammatory bowel disease (IBD). Mounting evidence suggests that therapeutic drug monitoring at induction may predict remission during maintenance. The aim of the study was to improve predictive models of remission by exploring new peak and intermediate infliximab measurements during induction.

METHODS

This was a prospective multicenter study evaluating the pharmacokinetics of infliximab during induction in a pioneer cohort of 63 patients with IBD. Pharmacokinetics data including peak, intermediate, and trough levels were combined with clinical and biological parameters and were subsequently fed into tailored logistic regression and tree-based techniques to predict remission at week 30.

RESULTS

Infliximab peak levels at week 2, intermediate levels at week 3, and trough levels at week 6 were correlated with remission at week 30. Predictive models exhibited an increased accuracy over the successive timepoints of the induction with key inputs such as albumin, C-reactive protein, eosinophils, neutrophils, lymphocytes, intermediate level at week 3, trough level at week 6, and age at diagnosis. Our predictive model of remission at week 30 was obtained with an area under the receiver operating characteristic curve of 0.9 ± 0.12, a sensitivity of 89%, and a specificity of 75%.

CONCLUSIONS

This study showed the clinical relevance of measuring new infliximab levels to predict remission in patients with IBD. These findings lay the foundation for a personalized medicine in which biotherapies could be monitored at an early stage, thereby improving patients' clinical management.

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.

Recent advancements in clearance monitoring of monoclonal antibodies in patients with inflammatory bowel diseases

INTRODUCTION

Less than 50% of patients with inflammatory bowel diseases (IBD) receiving monoclonal antibody (mAb) therapy achieve endoscopic remission. Poor outcomes may indicate a need for dose optimization. During therapeutic drug monitoring (TDM), drug concentrations are measured, and when found too low, dosage regimen escalations are performed. To date, benefits of TDM of mAbs in patients with IBD are uncertain.

AREAS COVERED

This review presents an overview of what clearance monitoring is, how it can be performed, and why and when it may be valuable in treating patients with IBD. Virtual patients were used for illustration. A literature search was performed to summarize current evidence for clearance monitoring in IBD and other disease settings.

EXPERT OPINION

During clearance monitoring, mAb clearance is calculated and monitored over time. Higher mAb clearance in patients with IBD has been associated with higher target load (target-mediated drug disposition), protein-losing enteropathy (fecal drug loss), and immunogenicity. Although not prospectively confirmed, clearance monitoring might facilitate identification of (yet) asymptomatic disease flares or presence of (yet) undetectable anti-drug antibodies. Furthermore, clearance monitoring may be used to predict treatment outcomes. Whether dosage regimen adjustments can modify the clearance time course and the treatment outcome is to be determined.

Ustekinumab induction concentrations are associated with clinical and biochemical outcomes at week 12 of treatment in Crohn's disease

BACKGROUND

We investigated relationships between induction ustekinumab levels and clinical and biochemical outcomes in Crohn's disease.

METHODS

Following standard IV induction, ustekinumab levels were measured at week 2 (wk2) and week 6 (wk6). Ustekinumab levels were compared in patients receiving 260, 390 and 520 mg at induction. Crohn's disease activity index (CDAI), serum albumin, C-reactive protein (CRP) and fecal calprotectin (FCP) were measured at baseline and week 12 (wk12). Associations between ustekinumab levels and these parameters were assessed. Ustekinumab levels were compared between patients requiring dose intensification within one year of induction and those remaining on standard dosing.

RESULTS

Of 23 wk2 ustekinumab levels, 22(95.7%) were above the upper limit of quantification of the assay (25 µg/mL). Median wk6 ustekinumab level (n = 25) was 14.2 μg/mL [interquartile range (IQR), 9.6-20.1]. Median wk6 ustekinumab levels in patients receiving 260, 390 and 520 mg were 8.6, 16.3 and 25.0 µg/mL, respectively, P = 0.01. There were significant correlations between baseline albumin and wk6 ustekinumab levels; r = 0.644 [95% confidence interval (CI), 0.304-0.839], P < 0.001, and between baseline FCP and wk6 ustekinumab levels; r = -0.678 (95% CI, -0.873 to -0.296), P < 00.01. Median wk12 CDAI (n = 18), CRP (n = 22) and FCP (n = 13) were 78 (IQR, 52.5-152), 1.75 mg/L (IQR, 0.93-7.03) and 746 μg/g (IQR, 259-2100), respectively. There were significant correlations between wk6 ustekinumab levels and wk12 CDAI; r = -0.513 (95% CI, -0.796 to -0.046), P = 0.03; and between wk6 ustekinumab levels and wk12 CRP; r = -0.578 (95% CI, -0.808 to -0.194), P < 0.01. Wk6 ustekinumab levels were lower in patients undergoing subsequent dose intensification; 12.5 vs. 19.6 µg/mL, P = 0.04.

CONCLUSION

Wk6 ustekinumab levels are significantly associated with baseline Crohn's disease biomarkers and subsequent clinical and biochemical outcomes.

Levels of Biosimilar Infliximab during and after Induction Treatment in Crohn's Disease and Ulcerative Colitis-A Prospective Polish Population Study

Background: Primary lack or secondary loss of response to therapy with infliximab is a significant problem. This study aimed to evaluate the response to treatment in patients with Crohn’s disease (CD) and ulcerative colitis (UC) achieving therapeutic and sub-therapeutic trough levels of biosimilar infliximab (CT-P13). Results: A total of 65 patients (32 with CD and 33 with UC) were recruited. The overall response rate in both CD and UC patients exceeded 80%. There were no significant differences in treatment response and CT-P13 levels for patients with CD or UC. We did not find significant differences in the percentage of patients achieving drug levels of 3 μg/mL at week 6, 10, or 12; a significant decrease was observed at week 14. Up to 55.5% of patients with CD and 64.3% of patients with UC with sub-therapeutic CT-P13 levels at week 14 primarily responded to treatment. Conclusions: Intermediate measurements of drug levels at weeks 10 and 12 did not capture any pronounced decrease in infliximab concentrations below therapeutic levels in either group, thus suggesting no clinical usefulness. A significant percentage of patients primarily responded to treatment despite sub-therapeutic drug levels after the induction phase.

Multi-alleles predict primary non-response to infliximab therapy in Crohn's disease

Background

Infliximab (IFX) is the first-line treatment for patients with Crohn's disease (CD) and is noted for its relatively high cost. The therapeutic efficacy of IFX has noticeable individual differences. Known single-gene polymorphisms (SNPs) are inadequate for predicting non-response to IFX. In this study, we aimed to identify new genetic factors associated with IFX-therapy failure and to predict non-response to IFX by developing a multivariate predictive model.

Methods

In this retrospective study, we collected and analysed the data of Chinese patients with CD who received IFX therapy at one hospital between June 2013 and June 2019. Primary non-response (PNR) and non-durable response (NDR) were evaluated using a simple endoscopic score for CD (SES-CD). A total of 125 SNPs within 44 genes were genotyped. A multivariate logistic-regression model was established to predict non-response to IFX. An area-under-the-receiver-operating-characteristics curve (AUROC) was applied to evaluate the predictive model performance.

Results

Forty-two of 206 (20.4%) patients experienced PNR and 15 of 159 (9.4%) patients experienced NDR. Nine SNPs were associated with PNR (P < 0.05). A PNR predictive model was established, incorporating 2-week high-sensitivity C-reactive protein (hs-CRP), rs61886887, rs61740234, rs357291, rs2269330, and rs111504845, and the AUROC on training and testing data sets were 0.818 (P < 0.001) and 0.888 (P < 0.001), respectively. At week 14, hs-CRP levels ≥ 2.25 mg/L were significantly associated with NDR (AUROC = 0.815, P < 0.001). PNR-associated SNPs were not mutually associated with NDR, suggesting distinct mechanisms between PNR and NDR.

Conclusion

Genetic polymorphisms are significantly associated with response to IFX among Chinese CD patients.

Therapeutic drug monitoring in inflammatory bowel disease: The dawn of reactive monitoring

Inflammatory bowel disease (IBD) is a chronic condition that significantly affects the quality of life of its patients. Biologic drugs have been the mainstay treatment in the management of IBD patients but despite their significant contribution, there remains a proportion of patients that do not respond or lose response to treatment. Therapeutic drug monitoring (TDM) involves measuring levels of serum drug concentrations and anti-drug antibodies. TDM of biologic drugs initially emerged to understand treatment failure in other immune mediated inflammatory diseases. This was then introduced in IBD to rationalize primary non-response or secondary loss of response, given that low serum drug concentrations or the formation of anti-drug antibodies are variably associated with treatment failure. The aim of this narrative review is to provide an overview regarding the current use of TDM in clinical practice and to present the evidence available regarding its use in both proactive and reactive clinical settings in preventing and managing treatment failure. This review also presents the existing evidence regarding the association of various clinical outcomes with specific thresholds of drug concentrations, in everyday practice. A narrative review of published articles and conference abstracts regarding the use of TDM in IBD management, through an electronic search using PubMed and ScienceDirect. TDM has proven to be superior and more cost effective in guiding management of patients with treatment failure compared to empiric dose escalation or change in treatment. Despite a trend towards an association between clinical outcomes and drug concentrations, proactive TDM based strategies have not been shown to achieve clear benefit in long-term outcomes. In the clinical setting, TDM has proven to be useful in managing IBD patients, and its use in the reactive setting, as an additional tool to help manage patients with treatment failure, is being promoted as newer guidelines and consensus groups implement TDM as part of the management plan.

Model-Informed Precision Dosing during Infliximab Induction Therapy Reduces Variability in Exposure and Endoscopic Improvement between Patients with Ulcerative Colitis

Model-informed precision dosing (MIPD) may be a solution to therapeutic failure of infliximab for patients with ulcerative colitis (UC), as underexposure could be avoided, and the probability of endoscopic improvement (pEI; Mayo endoscopic subscore ≤ 1) could be optimized. To investigate in silico whether this claim has merit, four induction dosing regimens were simulated: 5 mg/kg (label dosing), 10 mg/kg, covariate-based MIPD (fat-free mass, corticosteroid use, and presence of extensive colitis at baseline), and concentration-based MIPD (based on the trough concentration at day 14). Covariate- and concentration-based MIPD were chosen to target the same median area under the infliximab concentration-time curve up to endoscopy at day 84 (AUC_d84), as was predicted from 10 mg/kg dosing. Dosing at 5 mg/kg resulted in a mean ± standard deviation pEI of 55.7 ± 9.0%. Increasing the dose to 10 mg/kg was predicted to improve pEI to 65.1 ± 6.1%. Covariate-based MIPD reduced variability in exposure and pEI (65.1 ± 5.5%). Concentration-based MIPD decreased variability further (66.0 ± 3.9%) but did so at an increased average dose of 2293 mg per patient, as compared to 2168 mg for 10 mg/kg dosing. Mean pEI remained unchanged between 10 mg/kg dosing and MIPD, since the same median AUC_d84 was targeted. In conclusion, quantitative simulations predict MIPD will reduce variability in exposure and pEI between patients with UC during infliximab induction therapy.

Comparative effectiveness of higher adalimumab maintenance therapy versus standard dose in anti-tumor necrosis factor experienced Crohn's disease patients: A propensity-score matched cohort analysis

BACKGROUND AND AIM

Crohn's disease (CD) patients who previously failed anti-tumor necrosis factor (TNF) therapy are at higher risk of treatment failure with subsequent biologics. This study aims to determine the effectiveness and safety of higher maintenance dose regimens of adalimumab compared with standard doses in CD patients who failed anti-TNF.

METHODS

In this retrospective observational study, CD patients who failed anti-TNF and received adalimumab were categorized according to their post-induction maintenance regimen; 40 mg subcutaneous (sc) weekly or 80 mg sc every other week were defined as a high-dose (HD) maintenance regimen, and 40 mg sc every other week was defined as a standard-dose (SD) maintenance regimen. The primary outcome was time to treatment failure. Cox proportional hazards regression was used to adjust for confounders. Sensitivity analysis was conducted using propensity scores to create a cohort of matched participants with similar distribution of baseline covariates.

RESULTS

Forty patients started on HD regimens following induction, and 77 patients received the SD regimen. The median time to failure in the HD group was 6.6 years (interquartile range [IQR] 4.0-9.6) and 3.0 years (IQR 0.9-9.4) in the SD group (log-rank test P = 0.006). Patients on HD adalimumab had a lower hazard rate of treatment failure (hazard ratio: 0.27; 95% confidence interval [0.12, 0.62]; P = 0.002) compared with SD patients. No difference in adverse events was identified between groups (30% vs 31.2%, P = 1.0). Results were similar in the propensity score-matched cohort.

CONCLUSIONS

High-dose maintenance regimens were associated with longer time-to-failure as compared with SD regimens in CD patient who failed anti-TNF.

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.

External Model Performance Evaluation of Twelve Infliximab Population Pharmacokinetic Models in Patients with Inflammatory Bowel Disease

Infliximab is approved for treatment of various chronic inflammatory diseases including inflammatory bowel disease (IBD). However, high variability in infliximab trough levels has been associated with diverse response rates. Model-informed precision dosing (MIPD) with population pharmacokinetic models could help to individualize infliximab dosing regimens and improve therapy. The aim of this study was to evaluate the predictive performance of published infliximab population pharmacokinetic models for IBD patients with an external data set. The data set consisted of 105 IBD patients with 336 infliximab concentrations. Literature review identified 12 published models eligible for external evaluation. Model performance was evaluated with goodness-of-fit plots, prediction- and variability-corrected visual predictive checks (pvcVPCs) and quantitative measures. For anti-drug antibody (ADA)-negative patients, model accuracy decreased for predictions > 6 months, while bias did not increase. In general, predictions for patients developing ADA were less accurate for all models investigated. Two models with the highest classification accuracy identified necessary dose escalations (for trough concentrations < 5 µg/mL) in 88% of cases. In summary, population pharmacokinetic modeling can be used to individualize infliximab dosing and thereby help to prevent infliximab trough concentrations dropping below the target trough concentration. However, predictions of infliximab concentrations for patients developing ADA remain challenging.

Early Changes in Serum Albumin Predict Clinical and Endoscopic Outcomes in Patients With Ulcerative Colitis Starting Anti-TNF Treatment

BACKGROUND

Up to 60% of patients with ulcerative colitis (UC) ultimately fail anti-tumor necrosis factor (TNF) treatment. We aimed to investigate early predictive markers of clinical and endoscopic outcomes in patients with UC who were anti-TNF-naïve commencing anti-TNF treatment, with particular focus on changes in albumin and C-reactive protein levels in the first 2 weeks of treatment.

METHODS

We retrospectively investigated 210 patients with UC who started infliximab or adalimumab between 2009 and 2016 (male, 62.4%; median age at diagnosis, 37.9 years [interquartile range, 25.5-48.9 years]; median follow-up duration, 3.3 years [1.9-5.0 years]). Logistic and Cox proportional-hazards regressions were performed to identify variables associated with primary nonresponse (PNR), endoscopic outcomes, time-to-colectomy, and anti-TNF failure.

RESULTS

Forty-one patients (19.5%) experienced PNR; week 0/week 2 ratio serum albumin was associated with PNR (adjusted odds ratio [aOR], 1.8; 95% confidence interval [CI], 1.1-2.9, per interquartile range increase). Week 0/week 2 ratio albumin was also associated with endoscopic response (aOR, 0.28; 95% CI, 0.31-0.82) and endoscopic remission (aOR, 0.61; 95% CI, 0.39-0.96) at weeks 8 to 14, time-to-colectomy (adjusted hazard ratio, 2.12; 95% CI, 1.29-3.49) and time-to-anti-TNF failure (adjusted hazard ratio, 1.54; 95% CI, 1.22-1.96), regardless of age, disease severity, or in-patient status. Association with time-to-colectomy and anti-TNF failure was externally validated in an independent cohort of inpatients with UC starting infliximab.

CONCLUSIONS

Change in serum albumin within the first 2 weeks of anti-TNF treatment is predictive of PNR, endoscopic outcomes, time-to-colectomy, and anti-TNF failure in patients with UC. Timely access to this biomarker enables early identification of patients with UC at risk of anti-TNF failure and may guide early optimization of anti-TNF treatment to improve disease outcomes.

Factors Associated with the Immunogenicity of Anti-Tumor Necrosis Factor Agents in Pediatric Patients with Inflammatory Bowel Disease

BACKGROUND/AIMS

Anti-drug antibodies (ADAs) can develop during treatment with anti-tumor necrosis factor (TNF) agents. We aimed to investigate the factors associated with immunogenicity of anti-TNF agents in pediatric patients with inflammatory bowel disease (IBD) and observe the clinical course of ADA-positive patients.

METHODS

Pediatric IBD patients receiving maintenance treatment with anti-TNF agents who had been tested for ADAs against infliximab (IFX) or adalimumab (ADL) were included in this crosssectional study. Factors associated with ADA positivity were investigated by analyzing clinicodemographic, laboratory, and treatment-related factors.

RESULTS

A total of 76 patients (Crohn's disease, 65; ulcerative colitis, 11) were included. Among these, 59 and 17 patients were receiving IFX and ADL, respectively. ADAs were found in 10 patients (13.2%), all of whom were receiving IFX. According to multivariable logistic regression analysis, the IFX trough level (TL) was associated with ADA positivity (odds ratio, 0.25; 95% confidence interval [CI], 0.08 to 0.51; p=0.002). According to the receiver operating characteristic analysis, the optimal cutoff of the IFX TLs for stratifying patients based on the presence of ADAs against IFX was 1.88 μg/mL (area under curve, 0.941; 95% CI, 0.873 to 1.000; sensitivity, 80.0%; specificity, 95.9%; p<0.001). Among the 10 patients with ADAs against IFX, five patients (50%) switched to ADL within 1 year, while five patients (50%) kept receiving IFX. Transient ADAs were observed in three patients (30%).

CONCLUSIONS

IFX TL was the only factor associated with ADA formation in pediatric IBD patients receiving IFX. Future studies based on serial and proactive therapeutic drug monitoring are required in the future.

25 years of anti-TNF treatment for inflammatory bowel disease: lessons from the past and a look to the future

Anti-tumour necrosis factor (TNF) antibodies have been widely used for approximately 25 years now. The first clinical observations in patients with refractory Crohn's disease rapidly responding to infliximab prompted accelerated clinical development and approval for this indication. However, many questions remained unanswered when this treatment came to market related to maintenance schedules, pharmacokinetics, toxicity and positioning. Many of these open questions were addressed by investigators and sponsors during more than two decades of clinical use. The authors were among the first to use infliximab in Crohn's disease and felt that now is a good time to look back and draw lessons from the remarkable anti-TNF story. Even today, new insights continue to appear. But more importantly, what was learnt in the past 25 years has created a platform for future development of even stronger and safer therapies. We should not forget to learn from the past.

Anti-Drug Antibodies in Patients with Inflammatory Bowel Diseases Treated with Biosimilar Infliximab: A Prospective Cohort Study

Reports of the prevalence of antibodies to infliximab (anti-drug antibodies, ADA) are inconsistent due in part to the various assay formats used to monitor immunogenicity in the clinic and under clinical trial settings. This study aimed to determine the frequency of ADA in patients with inflammatory bowel disease (IBD) during induction and maintenance therapy with biosimilar infliximab (CT-P13) using the ELISA (enzyme-linked immunosorbent assay) method. In this prospective single-center study, we analyzed the incidence of ADA and the relationship between the presence of ADA and the following variables: gender, type of disease, immunosuppressive therapy used, and duration of treatment. A total of 84 patients with IBD received CT-P13 and were followed up for an average of 7 months. We found ADA in 50% of the patients with undetectable levels of the drug. The percentage of persons with antibodies detected during induction treatment was 11.3% compared to 9.6% during maintenance therapy. The analysis showed no relationship between response to treatment and antibody titers (p = 0.381). The study showed a statistically significant relationship between undetectable levels of CT-P13 and the presence of ADA at week 6 of therapy (i.e., ADA were detected in all the patients with undetectable levels of CT-P13). Patients with IBD and undetectable levels of CT-P13 before administration of the third induction dose were at high risk of the presence of anti-drug antibodies as well as primary non-response.