Higher Adalimumab Drug Levels During Maintenance Therapy for Crohn's Disease Are Associated With Biologic Remission

Infliximab serum concentrations and disease activity in perianal fistulizing Crohn's disease: a cross-sectional study

INTRODUCTION

Several studies associate the presence of higher serum concentrations of infliximab (IFX) with fistula healing in perianal Crohn's disease (CD). This study aimed to evaluate serum IFX concentrations in patients with perianal fistulizing CD (PFCD) in the presence or absence of general, clinical, and radiological activities.

METHODS

This was a cross-sectional study in patients with PFCD during maintenance treatment with IFX from two centers. Serum IFX concentrations were measured before their next infusion and anal fistulas were evaluated by clinical examination and magnetic resonance imaging (MRI), whenever possible, performed 90 days before or after serum collection. According to clinical scores, radiological activity, and disease markers, patients were classified as in remission or active disease. Mean serum IFX concentrations were compared between the groups.

RESULTS

Thirty-eight patients with PFCD were included. Demographic characteristics were similar in patients with remission or active disease. The overall mean serum IFX concentration of the entire sample (n = 38) was 5.21 ± 4.75 μg/mL (median 3.63; IQR 1.44-8.82). Serum IFX levels were 6.25 ± 5.34 μg/mL (median 3.62; IQR 1.95-11.03) in the 23 (60.5%) patients in remission and 3.63 ± 3.24 μg/mL (median 3.63; IQR 1.32-6.43; p = 0.226) in the 15 (39 .5%) who presented active disease. When evaluating general, clinical, and radiological activity of PFCD, and deep remission in isolation, no statistical difference between the groups was observed (p = 0.226, p = 0.418, p = 0.126, and p = 0.232, respectively). The 13 (34.2%) patients with an optimized dose of IFX had significantly higher serum concentrations than the remaining 25 (65.8%) with a standard dose: 8.33 ± 4.41 μg/mL (median 8.36; IQR 3.82-11.20) vs. 3.59 ± 4.13 μg/mL (median 1.97; IQR 1.18-3.85) -p = 0.002. Patients in remission and with an optimized IFX dose had significantly higher serum IFX concentrations than those with a standard dose (p = 0.006), whereas no significant difference was observed among those with active disease (p = 0.083).

CONCLUSION

There were no differences in IFX serum concentrations in patients with clinical or radiological active PFCD as compared with those in remission. Patients with an optimized IFX dose had significantly higher serum concentrations than those with a standard dose. Patients in remission and with an optimized IFX dose had significantly higher serum concentrations than those with a standard dose.

Efficacy and safety of infliximab and adalimumab in inflammatory bowel disease patients

INTRODUCTION

Inflammatory bowel disease (IBD), consists of two primary types: Ulcerative Colitis (UC) and Crohn's Disease (CD). Infliximab (IFX) and Adalimumab (ADA) are frequently utilized in the management of moderate to severe cases of IBD.

AIM

This study aimed to assess the efficacy and safety of IFX and ADA in individuals diagnosed with moderate to severe IBD.

METHOD

This study is a prospective open-labeled randomized parallel study that included moderate to severe IBD patients treated with either IFX or ADA. A total of 56 patients participated, with 34 patients received IFX and 22 patients received ADA. Various measures, including Crohn's Disease Activity Index (CDAI), Mayo Score/ Disease Activity Index (DAI), and C-reactive protein (CRP) levels, were taken at baseline and week 14 to assess the efficacy of the treatments. In addition, the levels of drugs and sTREM-1 were measured at 14 weeks. Patient safety was monitored throughout the study period.

RESULTS

In the group received IFX, there was a notable decrease in CDAI (P = 0.045), DAI (P = 0.026), and CRP (P = 0.023 for CD, and P = 0.021 for UC) levels. In addition, the group received ADA experienced a significant reduction in CDAI (P = 0.001), DAI (P = 0.032), and CRP (P < 0.018 for CD and P = 0.003 for UC) levels. Responders had higher drug concentrations than non-responders, notably IFX concentration was higher in responders with CD (P = 0.001) and UC (P < 0.001). ADA concentration was higher in UC (P <= 0.001) and all CD patients responded to the treatment. The same trend was observed for sTREM-1 levels in CD and UC patients (P = 0.042, and P = 0.015, respectively) in the IFX group. In UC patients treated with ADA, the level of sTREM-1 was significantly low (P = 0.002).

CONCLUSION

Both IFX and ADA have a good safety profile and deliver a beneficial clinical and laboratory response in moderate-severe IBD patients.

CLINICAL TRIAL REGISTRATION

This study is registered on ClinicalTrials.gov under the identifier NCT05291039. (You can access the study at https://clinicaltrials.gov/study/NCT05291039 (First Posted: March 22, 2022).

Characterization of Biologic Discontinuation Among Pediatric Patients with Crohn's Disease

BACKGROUND & AIMS

Biologic therapies may effectively treat Crohn's disease (CD), and pediatric patients who discontinue multiple biologics risk exhausting treatment options. The frequency and context of biologic discontinuation have not been well-characterized. We aimed to determine patterns of biologic use, discontinuation, and evaluation in pediatric patients with CD.

METHODS

Pediatric patients with CD at 7 U.S. centers (2010-2020) were identified. Prospective ImproveCareNow registry data were supplemented with medical record abstraction. Biologics included monoclonal antibody and small molecule medications. Therapeutic drug monitoring (TDM) was considered induction if <14 weeks after biologic start, proactive if later during quiescent disease, and reactive during active disease.

RESULTS

Of 823 patients included (median age, 13.0 years; 40% female), 86% started biologics (78% infliximab, 21% adalimumab, <1% others). Twenty-six percent used concomitant immunomodulators for ≥12 months. Most (85%) measured TDM including 47% induction, 69% proactive, and 24% reactive. Twenty-nine percent discontinued their first biologic after median 793 days because of inefficacy (34%), anti-drug antibodies (8%), adverse events (8%), or non-adherence (12%). If inefficacy, 86% underwent pre-discontinuation evaluation. If infliximab or adalimumab inefficacy and TDM was done, 62% had levels <10 μg/mL. Proactive TDM and concomitant immunomodulators were associated with 60% and 32% reduced biologic discontinuation.

CONCLUSIONS

Most children with CD are treated with biologics; 25%-37% discontinue biologics, resulting in 1 in 12 using >2 biologics during pediatric care. Half of patients discontinued biologics without trial of high-dose therapy and 14% without any evaluation. Concomitant immunomodulator use and proactive TDM decreased risk of biologic discontinuation. Strategies are needed to preserve biologic efficacy and prevent biologic discontinuation.

Prospective Evaluation of Serum Free Thiols in Inflammatory Bowel Disease: A Candidate to Replace C-Reactive Protein for Disease Activity Assessment?

BACKGROUND

Serum free thiols (SFTs) reflecting oxidative stress appear to correlate with inflammatory bowel disease (IBD) activity. We aimed to evaluate the performance of SFTs concentrations vs endoscopic and histological activity, compare SFTs with established biomarkers, and identify clinical and laboratory parameters independently associated with SFT levels in IBD patients.

METHODS

Patients with confirmed IBD undergoing routine ileocolonoscopy for activity assessment were prospectively recruited, with serum samples obtained concurrently for SFTs and routine bloods, plus fecal calprotectin and immunochemical tests were collected ±30 days from ileocolonoscopy. Endoscopic activity was assessed via established indices and histological activity graded as inactive/mild/moderate. Receiver-operating characteristic curve analyses were utilized to assess performance of SFTs vs endoscopic activity, and multiple regression analysis was used to identify factors associated with SFT levels.

RESULTS

A total of 141 (80 Crohn's disease, 61 ulcerative colitis) patients were recruited. Median SFTs were significantly lower in moderate vs inactive/mild endoscopic activity (309 µM vs 433/471 µM, respectively; P < .01). There was no significant difference in median SFTs across inactive/mild/moderate histological activity. SFTs achieved higher sensitivity than C-reactive protein in predicting moderate, endoscopically active disease (89% vs 78%; area under the curve, 0.80 each) yet was outperformed by fecal calprotectin (100%; area under the curve, 0.93). Advancing age and increasing albumin levels were independently associated with SFT levels, and thus are possible confounders.

CONCLUSIONS

This prospective study has demonstrated the potential of SFTs as a serum biomarker in IBD. It was more sensitive than C-reactive protein, yet less sensitive than fecal biomarkers for prediction of endoscopically active IBD.

The Future of Advanced Therapies for Pediatric Crohn's Disease

Pediatric Crohn's disease commonly presents with moderate-to-severe intestinal inflammation with a greater risk of complications if remission is not achieved. Anti-tumor necrosis factor therapies have offered the possibility of deep and durable remission; however, many children do not respond or no longer respond over time. Further, some children do not require broader systemic immunosuppression to achieve remission and are better served by an alternative treatment strategy. Proper utilization of advanced biologic and small-molecule therapies, which have become available for adult patients since anti-tumor necrosis factor medications, is paramount for tighter disease control for a large proportion of children. Newer advanced therapies such as anti-integrin and anti-interleukin biologics, and several small-molecule agents capitalize on various mechanisms through narrower immunologic targets and reduced immunogenicity. Given limited regulatory approvals of these agents for use in children with Crohn's disease, clinicians continue to rely on data extrapolated from clinical trials in adult patients, sparse pediatric studies, and a growing real-world experience for treatment selection and optimization. In this article, we discuss currently available treatment options, pipeline drugs, and relevant data as they pertain to some of the most pressing clinical challenges faced in treating pediatric Crohn's disease.

Rates, predictive factors and effectiveness of ustekinumab intensification to 4- or 6-weekly intervals in Crohn's disease

BACKGROUND

The UNITI trial reports efficacy of ustekinumab (UST) dose intensification in Crohn's disease (CD) from 12- to 8-weekly, but not 4-weekly. We aimed 1) to assess the cumulative incidence of UST dose intensification to 4- or 6-weekly, 2) to identify factors associated with dose intensification, and 3) to assess the effectiveness of this strategy.

METHODS

We performed a retrospective, observational cohort study in NHS Lothian including all UST treated CD patients (2015-2020).

RESULTS

163 CD patients were treated with UST (median follow-up: 20.3 months [13.4-38.4]), of whom 55 (33.7%) underwent dose intensification to 4-weekly (n = 50, 30.7%) or 6-weekly (n = 5, 3.1%). After 1 year 29.9% were dose intensified. Prior exposure to both anti-TNF and vedolizumab (HR 9.5; 1.3-70.9), and concomitant steroid use at UST start (HR 1.8; 1.0-3.1) were associated with dose intensification. Following dose intensification, 62.6% patients (29/55) remained on UST beyond 1 year. Corticosteroid-free clinical remission was achieved in 27% at week 16 and 29.6% at last follow-up.

CONCLUSION

One third of CD patients treated with UST underwent dose intensification to a 4- or 6-weekly interval within the first year. Patients who failed both anti-TNF and vedolizumab, or required steroids at initiation were more likely to dose intensify.

Advances in the Comprehensive Management of Postoperative Crohn's Disease

Patients with postoperative Crohn's disease are difficult to manage because of their risk of experiencing a more severe course, multiple symptom confounders, and poor sensitivity of symptomatic remission to rule out intestinal inflammation. In this group, data are lacking on biologic therapeutic efficacy, and recommendations are lacking for those with multiple medication failures. Novel noninvasive testing can simultaneously exclude alternate causes of symptoms (serum C4, fecal fat, small intestinal bowel overgrowth breath testing) and assess intestinal inflammation (fecal calprotectin, endoscopic healing index). In addition, endoscopy-based disease activity assessment and management are required. Endoscopy should be performed within 6 months of surgery, and aggressive disease activity monitoring can be considered with colonoscopy every 1-2 years subsequently to ensure late recurrence is detected. Patients with multiple resections should be screened for short bowel syndrome. Predictive biomarkers are needed to guide medication selection in this high-risk population. Postoperative prophylactic biologic therapy is prudent for patients with preoperative biologic failure. However, there are no high-quality data to guide which agent should be selected. Selecting biologics with an alternative mechanism of action in those who had failed a biologic with adequate drug concentrations and selection of different agents in those with previous intolerance are reasonable. Significantly more study is required to assess the efficacy of therapies in this setting.

Long-Term Outcomes With Adalimumab Therapy in Pediatric Crohn Disease: Associations With Adalimumab Exposure

BACKGROUND/AIMS

Pediatric Crohn disease (CD) treatment goals have evolved. Among children receiving adalimumab (ADA) we examined long-term durability of clinical remission, linear growth, and associations of trough concentration (TC) with biomarker, endoscopic and imaging outcomes.

METHODS

Single-center retrospective study. Pediatric CD activity index, C-reactive protein, fecal calprotectin, and height measured longitudinally. Discontinuation due to secondary loss of response (LOR) was assessed using Cox proportional hazards model. Associations between TC and clinical and biomarker remission, endoscopic and magnetic resonance imaging (MRI) improvements were assessed using Cox regression with time-dependent covariates.

RESULTS

Between January 2007 and June 2018, 213 children (median age 14.1 years (interquartile range [IQR] 12.5-15.7) 65% males) initiated ADA. One hundred and seventy-four (82%) achieved clinical remission (PCDAI < 10). During 24.8 (IQR 15.6-38.4) months follow-up, 26 (15%) discontinued ADA due to LOR, and 10 (6%) due to adverse events. Being anti-tumor necrosis factor (TNF) naïve and inflammatory behavior associated with increased likelihood of clinical remission (odds ratio [OR] 2.39, P = 0.033, and 3.13, P = 0.013, respectively) and with decreased LOR (hazard ratio [HR] 0.3, P = 0.002, and HR 0.35, P = 0.01, respectively). Cumulative LOR among 135 anti-TNF naïve patients: 0%, 8%, 15% within 1, 2, 3 years, similarly durable with mono- and immunomodulator combination therapy. Among pre-/early pubertal children mean height (-0.82) normalized to -0.07. TC consistently >7.5 ug/mL was associated with durable clinical remission (HR = 17.24, P < 0.001); TC >10 ug/mL with durable biomarker remission (HR = 6.56, P < 0.001) and endoscopic (OR 10.4, P = 0.002) and MRI (OR 7.6, P = 0.001) improvements.

CONCLUSION

ADA monotherapy maintains durable clinical remission. Biomarker remission, mucosal and transmural improvements were associated with greater ADA exposure.

Higher adalimumab maintenance regimen is more effective than standard dose in anti-TNF experienced Crohn's disease patients

BACKGROUND

Many Crohn's disease patients treated with anti-tumor necrosis factor (TNF) therapies suffer from loss of response over time and require dose escalation. The aim of this study was to evaluate the efficacy and safety of treating anti-TNF experienced Crohn's disease patients with higher maintenance regimens of adalimumab.

METHODS

In a retrospective observational study, Crohn's disease patients receiving adalimumab were categorized according to their maintenance regimen; 40 mg weekly, 80 mg every other week or greater were defined as a high-dose maintenance regimen and 40 mg every other week was defined as a standard maintenance regimen. The primary outcome was time to treatment failure.

RESULTS

Thirty-nine patients were started on high-dose regimens following induction and 40 patients received the standard regimen. According to a Kaplan-Meier survival curve analysis, time to treatment failure was significantly longer in patients in the high-dose group (P = 0.0015). Patients on high-dose adalimumab had a lower treatment failure rate (hazard ratio 0.21; P = 0.0005) when compared to patients on the standard regimen, after adjusting for induction dose and concomitant immunomodulator use. No difference in adverse events was identified between the groups (31 vs. 30%; P = 0.94).

CONCLUSION

High-dose maintenance regimens were more effective than the standard adalimumab maintenance protocol with better short and long-term clinical outcomes.

Immunogenicity of Tumor Necrosis Factor Antagonists and Effect of Dose Escalation on Anti-Drug Antibodies and Serum Drug Concentrations in Inflammatory Bowel Disease

BACKGROUND

Infliximab and adalimumab concentrations are associated with important outcomes in inflammatory bowel disease (IBD). Antibodies to infliximab (ATI) and adalimumab (ATA) are associated with reduced drug concentrations and worse outcomes. Because the efficacy of dose escalation to overcome antibodies is unclear, we assessed the impact of this strategy to overcome immunogenicity in IBD.

METHODS

Infliximab and adalimumab dosing, drug, and antibody concentrations were extracted from a database of patients with IBD having specimens collected for therapeutic drug monitoring. The primary outcome compared proportions with either infliximab ≥5 μg/mL or adalimumab ≥7.5 μg/mL and undetectable antibodies between dose-escalated and non-escalated patients. Area under the receiver operating characteristic curve analyses determined antibody concentrations below which dose escalation was associated with the primary outcome.

RESULTS

The study included 63,176 patients treated with infliximab and 46,429 patients treated with adalimumab. We detected ATI and ATA in 23.6% (n = 14,900) of patients treated with infliximab and 19.6% (n = 9101) of patients treated with adalimumab. In patients with ATI, infliximab dose escalation (n = 453) yielded higher proportions achieving the primary outcome (47.5% vs 30.9%; P < 0.001), greater drug concentration increases (5.9 μg/mL vs 0.2 μg/mL; P < 0.001), and ATI reductions (4.3 U/mL vs 1.9 U/mL; P = 0.002) compared to no escalation (n = 204). An ATI threshold of 8.55 U/mL was associated with achieving the primary outcome with dose escalation (area under the curve = 0.66). For patients with ATI ≤8.55 U/mL (n = 274), higher proportions (59.1% vs 29.6%; P < 0.001) achieved the primary outcome compared with those with ATI >8.55 U/mL (n = 179). No patients treated with adalimumab achieved the primary outcome (0/390), regardless of dose escalation (n = 87).

CONCLUSION

Dose escalation increased drug concentrations and eliminated antibodies with infliximab but not adalimumab. Initial ATI ≤8.55 U/mL was associated with increased efficacy of dose escalation using this assay.

Systematic review: efficacy of escalated maintenance anti-tumour necrosis factor therapy in Crohn's disease

BACKGROUND

Loss of response to anti-TNF agents is a common clinical problem. Dose escalation may be effective for reestablishing clinical response in Crohn's disease (CD).

AIMS

To perform a systematic review assessing the efficacy of escalated maintenance anti-TNF therapy in CD.

METHODS

EMBASE, MEDLINE, Web of Science, and CENTRAL databases were searched for English language publications through to April 25, 2021. Full-text articles evaluating escalated maintenance treatment (infliximab or adalimumab) in adult CD patients were included.

RESULTS

A total of 4733 records were identified, and 68 articles met eligibility criteria. Rates of clinical response (33%-100%) and remission (15%-83%) after empiric dose escalation for loss of response to standard anti-TNF therapy were high but varied across studies. Dose intensification strategies (doubling the dose versus shortening the therapeutic interval) were similarly efficacious. Dose-escalated patients tended to have higher serum drug levels compared to those on standard dosing. An exposure-response relationship following dose escalation was found in a number of observational studies. Randomised controlled trials comparing therapeutic drug monitoring (TDM) to empiric treatment intensification have failed to reach their primary end-points. Strategies including Bayesian dashboard-dosing and early treatment escalation targeting biomarker normalisation were found to be associated with improved long-term outcomes.

CONCLUSIONS

Empiric escalation of maintenance anti-TNF therapy can recapture clinical response in a majority of patients with secondary loss of response to standard maintenance doses. Proactive optimisation of maintenance dosing might prolong time to loss of response in some patients.

Association of Early Postinduction Adalimumab Exposure With Subsequent Clinical and Biomarker Remission in Children with Crohn's Disease

BACKGROUND

Data on the association between early postinduction serum adalimumab (ADA) trough levels (TLs) and objective outcomes are scarce. The aim of this study was to investigate whether early ADA TLs at weeks 4 and 8 are associated with clinical and biomarker remission at week 24 in pediatric Crohn's disease (CD).

METHODS

Adalimumab TLs at weeks 4 and 8 were prospectively measured in anti-TNF-naïve children initiating treatment with ADA monotherapy for luminal inflammatory CD. The primary outcome was combined clinical and biomarker remission at week 24, defined as achieving steroid-free clinical remission (Pediatric CD activity index <10) and biomarker remission (fecal calprotectin <250 µg/g and CRP <5 µg/mL).

RESULTS

Among 65 patients, 39 (60%) achieved combined clinical/biomarker remission at week 24 without dose escalation. Adalimumab TLs at both weeks 4 and 8 were significantly higher in remitters vs nonremitters at week 24 (P < 0.001 and P = 0.002, respectively). Adalimumab levels at weeks 4 and 8 were good predictors of combined clinical/biomarker remission at week 24 (area under the curve, 0.887, 95% CI, 0.798-0.942; and area under the curve, 0.761, 95% CI, 0.632-0.899, respectively). The best ADA TL cutoffs at weeks 4 and 8 for predicting clinical/biomarker remission at week 24 were 22.5 µg/mL (80% sensitivity, 90% specificity, positive likelihood ratio [LR+] 8.0, negative LR [LR-] 0.2) and 12.5 µg/mL (94% sensitivity, 60% specificity, LR+ 2.4, LR- 0.1), respectively. Higher induction doses per m2 correlated positively with TLs at weeks 4 and 8.

CONCLUSION

Greater early ADA exposure is associated with superior clinical/biomarker outcomes at week 24.

Effectiveness and Safety of Adalimumab Biosimilar SB5 in Inflammatory Bowel Disease: Outcomes in Originator to SB5 Switch, Double Biosimilar Switch and Bio-Naïve SB5 Observational Cohorts

BACKGROUND AND AIMS

Multiple adalimumab [ADA] biosimilars are now approved for use in inflammatory bowel disease [IBD]; however, effectiveness and safety data remain scarce. We aimed to investigate long-term outcomes of the ADA biosimilar SB5 in IBD patients following a switch from the ADA originator [SB5-switch cohort] or after start of SB5 [SB5-start cohort].

METHODS

We performed an observational cohort study in a tertiary IBD referral centre. All IBD patients treated with Humira underwent an elective switch to SB5. We identified all these patients in a biological prescription database that prospectively registered all ADA start and stop dates including brand names. Data on IBD phenotype, C-reactive protein [CRP], drug persistence, ADA drug and antibody levels, and faecal calprotectin were collected.

RESULTS

In total, 481 patients were treated with SB5, 256 in the SB5-switch cohort (median follow-up: 13.7 months [IQR 8.6-15.2]) and 225 in the SB5-start cohort [median follow-up: 8.3 months [4.2-12.8]). Of the SB5-switch cohort, 70.8% remained on SB5 beyond 1 year; 90/256 discontinued SB5, mainly due to adverse events [46/90] or secondary loss of response [37/90]. In the SB5-start cohort, 81/225 discontinued SB5, resulting in SB5-drug persistence of 60.3% beyond 1 year. No differences in clinical remission [p = 0.53], CRP [p = 0.80], faecal calprotectin [p = 0.40] and ADA trough levels [p = 0.55] were found between baseline, week 26 and week 52 following switch. Injection site pain was the most frequently reported adverse event.

CONCLUSION

Switching from ADA originator to SB5 appeared effective and safe in this study with over 12 months of follow-up.

Serum Adalimumab Levels After Induction Are Associated With Long-Term Remission in Children With Inflammatory Bowel Disease

Introduction: Adalimumab is effective in inducing and maintaining remission in children with inflammatory bowel diseases (IBD). Therapeutic drug monitoring is an important strategy to maximize the response rates, but data on the association of serum adalimumab levels are lacking. This study aimed to assess the association of adalimumab concentrations at the end of induction and early during maintenance for long-term response. Materials and Methods: Serum samples for adalimumab level measurement were collected during routine visits between adalimumab administrations and therefore not necessarily at trough, both during the induction (week 4 ± 4) and maintenance phases (week 22 ± 4, 52 ± 4, and 82 ± 4). Adalimumab and anti-adalimumab antibodies were measured retrospectively using enzyme-linked immunosorbent assays (ELISA). Disease activity was determined by Pediatric Crohn's Disease Activity Index or Pediatric Ulcerative Colitis Activity Index. Results: Thirty-two children (median age 14.9 years) were enrolled. Sixteen, 15, 14, and 12 patients were in remission at weeks 4, 22, 52, and 82, respectively. Median adalimumab concentration was higher at all time points in patients achieving sustained clinical remission. Adalimumab levels correlated with clinical and biochemical variables. Adalimumab concentration above 13.85 and 7.54 μg/ml at weeks 4 and 22 was associated with remission at weeks 52 and 82. Conclusions: Adalimumab non-trough levels are associated with long-term response in pediatric patients with IBD.

Correlation of serum levels of anti-tumor necrosis factor agents with perianal fistula healing in Crohn's disease: a narrative review

With the overspread use of measurement of serum levels of anti-tumor necrosis factor (TNF) agents (therapeutic drug monitoring, TDM), new therapeutic strategies have been used in the management of Crohn’s disease (CD). Different targets are correlated with increased levels of circulating drugs. Recent evidence demonstrated that higher serum levels of anti-TNF agents may be associated to better outcomes in perianal fistulizing CD (PFCD). Overall, patients with healed fistulas had higher serum levels of infliximab and adalimumab as compared to those with active drainage. This was demonstrated in some cohort studies, in induction and maintenance, in adults and children with PFCD. In this narrative review, authors summarize current evidence on the use of serum level measurement of anti-TNF agents and its correlation with perianal fistula healing in CD patients. Data on the use of TDM in PFCD is discussed in detail. The retrospective design of the studies and the lack of objective parameters to measure fistula healing are the main limitations of published data. Prospective studies, with central reading of objective radiological parameters, such as pelvic magnetic resonance imaging scores, can improve the level of evidence on the possible advantages of TDM in perianal fistula in CD and are warranted.

Higher anti-tumor necrosis factor levels are associated with perianal fistula healing and fistula closure in Crohn's disease

OBJECTIVE

Limited data are available regarding the relationship between anti-tumor necrosis factor (TNF) drug/antibody levels and perianal fistula outcomes in Crohn's disease. The aims of this study were to assess the relationship between maintenance anti-TNF levels and perianal fistula outcomes.

METHODS

This was a retrospective cross-sectional study of patients receiving maintenance adalimumab or infliximab therapy (minimum 24 weeks) for the treatment of Crohn's disease with associated perianal fistulas, who had anti-TNF drug/antibody levels (trough for infliximab) measured within 4 weeks of clinical assessment. The primary outcome was the association of anti-TNF levels with perianal fistula healing defined as the absence of drainage. The secondary outcome was the association of anti-TNF levels with complete perianal fistula closure.

RESULTS

A total of 64 patients (adalimumab, n = 35; infliximab, n = 29) were included. Patients with fistula healing had higher levels of anti-TNF vs. those without fistula healing (adalimumab: 12.6 vs. 2.7 μg/mL, P < 0.01; infliximab: 8.1 vs. 3.2 μg/mL, P < 0.01). Patients with fistula closure also had significantly higher anti-TNF levels vs. those without fistula closure (adalimumab: 14.8 vs. 5.7 μg/mL, P < 0.01; infliximab: 8.2 vs. 3.2 μg/mL, P < 0.01). For adalimumab, receiver operator characteristic analysis identified an optimum level of >6.8 μg/mL and >9.8 μg/mL for fistula healing and closure, respectively. For infliximab, receiver operator characteristic analysis identified an optimum trough level of >7.1 μg/mL for both fistula healing and closure.

CONCLUSION

Higher maintenance anti-TNF levels are associated with perianal fistula healing and closure in Crohn's disease.

Distinct Cutoff Values of Adalimumab Trough Levels Are Associated With Different Therapeutic Outcomes in Patients With Inflammatory Bowel Disease

Background and Aims

We aimed to evaluate the relationship of serum adalimumab trough levels (ATL) with disease activity of inflammatory bowel disease (IBD) patients in a large, well-characterized referral center-based cohort.

Methods

We compared serum ATL between those with clinical, biochemical, or endoscopic/radiologic disease activity and those without.

Results

A total of 236 patients with IBD were included. Higher cutoff levels were associated with endoscopic and/or radiologic responses (cutoff value: 5.3 mcg/mL, P = 0.003) compared with improvement in C-reactive protein (cutoff value: 4.3 mcg/mL, P = 0.031).

Conclusions

Higher cutoff ATL was associated with endoscopic and/or radiologic response.

Subcutaneous Absorption Contributes to Observed Interindividual Variability in Adalimumab Serum Concentrations in Crohn's Disease: A Prospective Multicentre Study

BACKGROUND AND AIM

Therapeutic drug monitoring is used to optimise adalimumab therapy in patients with Crohn's disease [CD]. However, the interindividual variability in drug absorption and the quantitative effect on drug clearance of anti-adalimumab antibodies [AAA], measured with a drug-resistant assay, are unclear. We aimed to characterise adalimumab population pharmacokinetics [PopPK] and identify determinants of interindividual variability in patients with CD.

METHODS

In a prospective multicentre open-label cohort study in 28 patients with CD starting adalimumab therapy peak, intermediate, and trough serum samples were analysed for adalimumab and AAA concentrations using a drug resistant assay. Adalimumab concentration-time data were analysed by non-linear mixed effects modelling and were adequately described by a PopPK model with first-order absorption and one-compartment disposition with linear elimination. Clinical remission at Week 12 [W12] was defined as a Harvey-Bradshaw index ≤4.

RESULTS

The absorption rate, volume of distribution, and clearance estimates of a typical patient were respectively 0.343 /day, 7.8 L, and 0.330 L/day. A 4-fold difference in the range of adalimumab concentrations was observed 7 days after the first dose and found to be inversely correlated with baseline lean body weight [LBW], soluble tumour necrosis factor [s-TNF], and s-TNF receptor-1 whereas positive AAA and higher LBW were found to be important predictors of accelerated clearance. An adalimumab concentration at W12 of >7.3 µg/mL was significantly associated with achieving clinical remission at W12.

CONCLUSION

Variability in subcutaneous drug absorption is an important contributor to the observed interindividual variability in adalimumab concentrations, in addition to drug clearance [ClinicalTrials.gov NCT02450513].

Association of trough vedolizumab levels with clinical, biological and endoscopic outcomes during maintenance therapy in inflammatory bowel disease

OBJECTIVE

To establish the relationship between trough vedolizumab levels and outcomes during maintenance therapy.

DESIGN

Cross-sectional service evaluation was performed on patients with inflammatory bowel disease (IBD) receiving maintenance vedolizumab therapy (minimum of 12 weeks following induction). Prior to infusion, data on clinical activity (Harvey-Bradshaw Index or partial Mayo score), trough C-reactive protein (CRP)/vedolizumab levels and faecal calprotectin were collected. Endoscopic data (±8 weeks from vedolizumab level testing) were obtained by review of medical records. Vedolizumab levels were processed using the Immundiagnostik monitor ELISA.

SETTING

The Edinburgh IBD Unit, Western General Hospital (tertiary IBD referral centre).

PATIENTS

Seventy-three patients (30 ulcerative colitis and 43 Crohn's disease) were identified who fulfilled inclusion criteria and had vedolizumab levels matched with clinical activity scores, CRP and faecal calprotectin. Of these, 40 patients also had matched endoscopic data.

MAIN OUTCOME MEASURES

The association of trough vedolizumab levels with clinical remission (Harvey-Bradshaw Index <5 or partial Mayo <2), biologic remission (faecal calprotectin <250 µg/g+CRP <5 mg/L) and endoscopic remission (Mayo score 0/no inflammation and ulceration on colonoscopy).

RESULTS

The median trough vedolizumab levels were similar between patients in and not in clinical remission (10.6 vs 9.9 µg/mL, p=0.54); biologic remission (10.6 vs 9.8 µg/mL, p=0.35) and endoscopic remission (8.1 vs 10.2 µg/mL, p=0.21). Quartile analysis revealed no significant increase in the proportion of patients in clinical remission, biologic remission or endoscopic remission with increasing trough vedolizumab levels (p<0.05).

CONCLUSIONS

In this cohort, trough vedolizumab levels were not associated with clinical, biological or endoscopic outcomes during maintenance therapy.

Advances in Therapeutic Drug Monitoring for Small-Molecule and Biologic Therapies in Inflammatory Bowel Disease

PURPOSE OF REVIEW

Therapeutic drug monitoring (TDM) is increasingly utilized as a strategy to optimize inflammatory bowel disease (IBD) therapeutics. As management paradigms have evolved towards treat-to-target strategies, there has been growing interest in expanding the role of TDM to guide drug optimization for achieving objective endpoints. This review summarizes the evidence for using TDM with biologic and oral small-molecule therapies, evaluates the role of reactive versus proactive TDM in treatment algorithms, and identifies potential future applications for TDM.

RECENT FINDINGS

Achieving therapeutic drug concentrations has been associated with important clinical, endoscopic, and histologic outcomes in IBD. However, the optimal drug concentration varies by therapeutic agent, disease phenotype, inflammatory burden, phase of treatment, and target outcome. Traditionally, TDM has been used reactively to define pharmacokinetic versus mechanistic failures after loss of response to a tumor necrosis factor-α (TNF) antagonist and while observational data suggests a benefit to proactive TDM, this has not been definitively confirmed in prospective randomized controlled trials. The role of TDM in optimizing vedolizumab, ustekinumab, and tofacitinib remains unclear, given differences in pharmacokinetics and immunogenicity compared to TNF antagonists. Measuring drug action at the site of inflamed tissue may provide additional insights into treatment optimization. The use of TDM offers the possibility of a more personalized treatment approach for patients with IBD. High-quality studies are needed to delineate the role of proactive TDM for maintaining remission, for optimizing induction regimens, and for novel agents.