Pharmacokinetic Dashboard-Recommended Dosing Is Different than Standard of Care Dosing in Infliximab-Treated Pediatric IBD Patients

"Getting the Dose Right"-Revisiting the Topic With Focus on Biologic Agents

Nearly two decades after the Peck and Cross article '"Getting the dose right: facts, a blueprint, and encouragements" was published, a review of dose recommendations for biologics shows that the success in getting the dose right appears to have improved given the relatively low incidence of drug withdrawals and dosing/label changes. However, the clinical experience with monoclonal antibodies (MAbs) following approval has been less than perfect. In inflammatory diseases, the disease burden changes with time and high treatment failure rates have been reported. In addition, the use of concomitant steroids and immunosuppressant drugs with MAbs is common. These concomitant agents have their own safety issues and many immunosuppressant agents are not well-tolerated although they have been shown to reduce the incidence of anti-drug antibodies (ADA). This same complexity is seen in MAbs used in oncology as well, although with these agents the doses appear to be higher than needed, which results in high treatment costs and incidence of adverse events. Given the complexity of MAb pharmacokinetics, which makes providing a detailed description of dose options difficult, product labeling should include the options for alternative dose strategies and potentially include the use of therapeutic drug monitoring with dose individualization which have been shown to improve clinical response and reduce the incidence of ADA. So, while the recommended dosing for biologics seems improved over the issues noted 17 years ago, we still have some work to do.

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.

Forecasted infliximab concentrations during induction predict time to remission and sustained disease control of inflammatory bowel disease

BACKGROUND

Infliximab (IFX) exposure is established as a predictive factor of pharmacokinetic (PK) origin in inflammatory bowel disease (IBD), and expert consensus is to achieve adequate exposure during induction to achieve and sustain remission.

METHODS

We retrospectively evaluated the performance of a Bayesian PK tool in IBD patients starting IFX. Trough IFX serum levels collected immediately before the third (at week 6) and fourth (at week 14) infusions were evaluated from 307 IBD patients (median age=17 years, 50 % females, 83 % with Crohn's disease). Forecasted IFX concentration at the fourth infusion were estimated using serum IFX, antibodies to IFX, albumin and weight determined immediately before the third infusion using population PK calculator with Bayesian prior. The outcome variable was a clinical & biochemical remission status achieved (CRP levels below 3 mg/L in presence of clinical remission). Statistics consisted of Kaplan Meier analysis with calculation of Hazard ratio (HR), and logistic regression.

RESULTS

IFX concentration above 15 µg/mL immediately before the third infusion associated with shorter time to clinical & biochemical remission than concentration below 15 µg/mL without reaching significance (163±14 days vs 200±16 days, respectively; p=0.052). However, using PK parameters at the third infusion, forecasted IFX concentrations above 10 µg/mL immediately before the fourth infusion were significantly associated with a higher rate (HR=1.6 95 %CI: 1.1 to 2.1 p<0.01) and shorter time to remission (148±18 days vs 200±13 days p<0.01). In the presence of IFX concentration above 15 µg/mL at the third infusion, there was a significant 2.5-fold higher likelihood of sustained clinical & biochemical remission status during maintenance as compared to IFX concentrations below 15 µg/mL (p<0.01). Forecasted IFX level above 10 µg/mL at fourth infusion associated with significantly 3.9-fold higher likelihood of clinical & biochemical remission as compared to forecasted IFX concentrations below 10 µg/mL (p<0.01).

CONCLUSIONS

These data further support that optimized IFX concentrations during induction are associated with enhanced disease control in IBD.

Performance of Eight Infliximab Population Pharmacokinetic Models in a Cohort of Dutch Children with Inflammatory Bowel Disease

BACKGROUND AND OBJECTIVE

Efficacy of infliximab in children with inflammatory bowel disease can be enhanced when serum concentrations are measured and further dosing is adjusted to achieve and maintain a target concentration. Use of a population pharmacokinetic model may help to predict an individual's infliximab dose requirement. The aim of this study was to evaluate the predictive performance of available infliximab population pharmacokinetic models in an independent cohort of Dutch children with inflammatory bowel disease.

METHODS

In this retrospective study, we used data of 70 children with inflammatory bowel disease (443 infliximab concentrations) to evaluate eight models that focused on infliximab pharmacokinetic models in individuals with inflammatory bowel disease, preferably aged ≤ 18 years. Predictive performance was evaluated with prior predictions (based solely on patient-specific covariates) and posterior predictions (based on covariates and infliximab trough concentrations). Model accuracy and precision were calculated with relative bias and relative root mean square error and we determined the classification accuracy at the trough concentration target of ≥ 5 mg/L.

RESULTS

The population pharmacokinetic model by Fasanmade was identified to be most appropriate for the total dataset (relative bias before/after therapeutic drug monitoring: -20.7%/11.2% and relative root mean square error before/after therapeutic drug monitoring: 84.1%/51.6%), although differences between models were small and several were deemed suitable for clinical use. For the Fasanmade model, sensitivity and specificity for maximum posterior predictions for the next infliximab trough concentration to be ≥ 5 mg/L were respectively 83.5% and 80% with an area under the receiver operating characteristic curve of 0.870.

CONCLUSIONS

In our paediatric cohort, various models provided acceptable predictive performance, with the Fasanmade model deemed most suitable for clinical use. Model-informed precision dosing can therefore be expected to help to maintain infliximab trough concentrations in the target range.

Application of a Precision-Dosing Model to a Real-World Cohort of Patients on Infliximab Maintenance Therapy: Drug Usage and Cost Analysis

Precision-dosing models forecast infliximab doses to achieve targeted trough concentrations in patients with inflammatory bowel disease (IBD). These models have shown to reduce nonresponse and improve patient outcomes. We compared infliximab doses determined by iDOSE precision dosing with standard dosing, and the associated drug costs, in patients with IBD. In this retrospective study, patients with IBD treated with infliximab every 8 weeks at 5 mg/kg were included. An infliximab dose was named dose X if 3 previous infliximab doses, laboratory values including trough infliximab concentrations, and the patient's weight were recorded. The actual dose X was compared to an iDOSE-predicted dose X. Net drug use and costs were evaluated. A total of 174 patients-56% men; median age, 36 (interquartile range, 29-47) years; 135 with Crohn disease; and 31 with ulcerative colitis-were included, with 417 dose X recordings. Median prior infliximab therapy was 2 (0-4) years. Comparing actual dose X with predicted dose X, 52% and 32% of doses were subtherapeutic when aiming for trough concentrations of 5-10 and 3-7 μg/mL, respectively. Treatment costs increased by 102% and 29% for the 2 trough ranges, respectively. On multivariate regression analysis, subtherapeutic infliximab concentrations were associated with ulcerative colitis compared with Crohn disease (odds ratio, 9.81; 95% confidence interval, 1.28-75.40; P = .028) and predose X infliximab trough concentration [odds ratio, 0.07; 95% confidence interval, 0.03-0.15; P < .001]. Over half of maintenance infliximab drug doses were too low to achieve infliximab blood concentrations of 5 μg/mL or greater. While applying precision dosing may improve patient outcomes, drug costs could be considerably greater.

Adalimumab Clearance, Rather Than Trough Level, May Have Greatest Relevance to Crohn's Disease Therapeutic Outcomes Assessed Clinically and Endoscopically

OBJECTIVE

We postulated that adalimumab [ADA] drug clearance [CL] may be a more critical determinant of therapeutic outcome than ADA concentration. This was tested in Crohn's disease [CD] patients undergoing ADA maintenance treatment.

METHODS

CD patients from four cohorts received ADA induction and started maintenance therapy. Therapeutic outcomes consisted of endoscopic remission [ER], sustained C-reactive protein [CRP] based clinical remission [defined as CRP levels below 3 mg/L in the absence of symptoms], and faecal calprotectin [FC] level below 100 µg/g. Serum albumin, ADA concentration, and anti-drug antibody status were determined using immunochemistry and homogeneous mobility shift assay, respectively. CL was determined using a nonlinear mixed effect model with Bayesian priors. Statistical analysis consisted of Mann-Whitney test and logistic regression with calculation of odds ratio. Repeated event analysis was conducted using a nonlinear mixed effect model.

RESULTS

In 237 enrolled patients [median age 40 years, 45% females], median CL was lower in patients achieving ER as compared with those with persistent active endoscopic disease [median 0.247 L/day vs 0.326 L/day, respectively] [p <0.01]. There was no significant difference in ADA concentration between patients in endoscopic remission compared with those with recurrence [median 9.3 µg/mL vs 11.7 µg/mL, respectively]. Sustained CRP-based clinical remission and FC levels below 100 µg/g were generally associated with lower CL and higher ADA concentration. Repeated event analysis confirmed those findings with better performances of CL than concentration in associating with ER and other outcomes.

CONCLUSION

Lower ADA clearance is associated with an improved clinical outcome for patients with Crohn's disease and may be a superior pharmacokinetic measure than concentration.

Therapeutic drug monitoring in inflammatory bowel disease: A practical approach

The global burden of inflammatory bowel diseases (IBD) is estimated at 4.9 million and the global prevalence exceeds 0.3%. Multiple newer therapeutic agents have broadened the options for the therapy of IBD in the last three decades. Thiopurines, however, have retained their place as maintenance therapy in IBD, especially in resource-constrained setting. But thiopurines have narrow therapeutic range, often needing discontinuation due to side effects or lack of efficacy. Biologic agents revolutionized the treatment of IBD, but the efficacy is lost in 50% of patient after one year. These outcomes are often due to inadequate drug concentrations that may lead to the development of antibodies as well as pharmacodynamic failure. Therapeutic drug monitoring (TDM) was proposed to reduce loss of response and to optimize the therapy in patients on thiopurine and biologic therapy. TDM is based on exposure-response relationship, suggesting a positive correlation between elevated serum anti-TNF concentrations and favorable therapeutic outcomes. TDM has multiple facets. This article discusses the benefits, evidence and limitations of TDM. The practical use of TDM in clinical practice is highlighted. Newer developments in the field and their relevance in practice are discussed.

Drug Clearance in Patients with Inflammatory Bowel Disease Treated with Biologics

Biological therapy is very effective for treating patients with moderate to severe inflammatory bowel disease (IBD). However, up to 40% can have primary non-response, and up to 50% of the patients can experience a loss of response to anti-tumor necrosis factor therapy. These undesirable outcomes can be attributed to either a mechanistic failure or pharmacokinetic (PK) issues characterized by an inadequate drug exposure and a high drug clearance. There are several factors associated with accelerated clearance of biologics including increased body weight, low serum albumin and immunogenicity. Drug clearance has gained a lot of attention recently as cumulative data suggest that there is an association between drug clearance and therapeutic outcomes in patients with IBD. Moreover, clearance is used by model informed precision dosing (MIDP) tools, or PK dashboards, to adjust the dosing for reaching a target drug concentration threshold towards a more personalized application of TDM. However, the role of drug clearance in clinical practice is yet to be determined. This comprehensive review aims to present data regarding the variables affecting the clearance of specific biologics, the association of clearance with therapeutic outcomes and the role of clearance monitoring and MIPD in patients with IBD.

The Combination of Predictive Factors of Pharmacokinetic Origin Associates with Enhanced Disease Control during Treatment of Pediatric Crohn's Disease with Infliximab

Infliximab (IFX) concentrations are a predictive factor (PF) of pharmacokinetic (PK) origin in the treatment of Crohn's disease (CD). We evaluated Clearance, another PF of PK origin, either alone or in combination with concentrations. They were evaluated from two cohorts, the first designed to receive standard dosing (n = 37), and the second designed to proactively target therapeutic IFX concentrations (n = 108). Concentrations were measured using homogeneous mobility shift assay. Clearance was estimated using the nonlinear mixed effects methods with Bayesian priors. C-reactive protein-based clinical remission (<3 mg/L in the absence of symptoms) was used for the disease control outcome measure. Longitudinal changes in disease control due to factors including time, IFX concentration, and Clearance were analyzed using repeated event analysis. Change in objective function value (∆OFV) was calculated to compare concentration and Clearance. The results indicated that lower baseline Clearance and proactive dosing associated with enhanced disease control during induction (p < 0.01). Higher IFX concentrations and lower Clearance measured at the second, third, and fourth infusion yielded improved disease control during maintenance (p < 0.032). During maintenance, the association with disease control was better with Clearance than with concentrations (∆OFV = -19.2; p < 0.001), and the combination of both further minimized OFV (p < 0.001) with markedly improved clinical yield in the presence of both PF of PK origin. We conclude that the combination of IFX concentration and Clearance are better predictors of therapeutic outcome compared with either one alone.

The Role of Therapeutic Drug Monitoring in Children

The use of biologic therapies has changed the treatment landscape for children with inflammatory bowel disease. While the novel biologics have improved clinical outcomes, there remains a significant gap in achieving endoscopic remission, prolonged steroid-free remission, and drug durability. Contributing to this gap is the paucity of real-world pharmacokinetic studies in children and a failure to dose optimize therapy during induction. Emerging data from a pediatric clinical trial and several observational studies have shown that the combination of proactive therapeutic drug monitoring and achievement of early therapeutic concentrations is effective in achieving improved outcomes. The next steps will be to leverage these past studies to develop more innovative clinical trials to properly assess the safety and effectiveness of proactive therapeutic drug monitoring in children.

Multicenter Cohort Study of Infliximab Pharmacokinetics and Therapy Response in Pediatric Acute Severe Ulcerative Colitis

BACKGROUND & AIMS

We aimed to model infliximab (IFX) pharmacokinetics (PK) in pediatric acute severe ulcerative colitis (ASUC) and assess the association between PK parameters, including drug exposure, and clinical response.

METHODS

We studied a multicenter prospective cohort of hospitalized children initiating IFX for ASUC or IBD-unclassified. Serial IFX serum concentrations over 26 weeks were used to develop a PK model. We tested the association of PK parameter estimates with day 7 clinical response, week 8 clinical remission, week 26 corticosteroid-free clinical remission (CSF-CR) (using the Pediatric Ulcerative Colitis Activity Index), and colectomy-free survival.

RESULTS

Thirty-eight participants received IFX (median initial dose, 9.9 mg/kg). Day 7 clinical response, week 8 clinical remission, and week 26 CSF-CR occurred in 71%, 55%, and 43%, respectively. Albumin, C-reactive protein, white blood cell count, platelets, weight, and antibodies to IFX were significant covariates incorporated into a PK model. Week 26 non-remitters exhibited faster IFX clearance than remitters (P = .013). However, cumulative IFX exposure did not differ between clinical response groups. One (2.7%) and 4 (10.8%) participants underwent colectomy by week 26 and 2 years, respectively. Day 3 IFX clearance >0.02 L/h was associated with colectomy (hazard ratio, 58.2; 95% confidence interval, 6.0-568.6; P < .001).

CONCLUSIONS

At median higher-than-label IFX dosing for pediatric ASUC, baseline faster IFX CL was associated with colectomy and at week 26 with lack of CSF-CR. IFX exposure was not predictive of clinical outcomes. Higher IFX dosing may sufficiently optimize early outcomes in pediatric ASUC. Larger studies are warranted to determine whether sustained intensification can overcome rapid clearance and improve later outcomes.

CLINICALTRIALS

gov identifier: NCT02799615.

Personalized Dosing of Infliximab in Patients With Inflammatory Bowel Disease Using a Bayesian Approach: A Next Step in Therapeutic Drug Monitoring

Although biological agents have revolutionized the management of inflammatory bowel diseases (IBDs), a significant proportion of patients show primary non-response or develop secondary loss of response. Therapeutic drug monitoring (TDM) is advocated to maintain the efficacy of biologic agents. Reactive TDM can rationalize the management of primary non-response and secondary loss of response and has shown to be more cost-effective compared with empiric dose escalation. Proactive TDM is shown to increase clinical remission and the durability of the response to a biologic agent. However, the efficacy of proactive and reactive TDM has been questioned in recent studies and meta-analyses. Hence, we need a different approach to TDM, which addresses inflammatory burden, the individual patient, and disease factors. Bayesian approaches, which use population pharmacokinetic models, enable clinicians to make better use of TDM for dose adjustment. With rapid improvement in computer technology, these Bayesian model-based software packages are now available for clinical use. Bayesian dashboard systems allow clinicians to apply model-based dosing to understand an individual's pharmacokinetics and achieve a target serum drug concentration. The model is updated using previously measured drug concentrations and relevant patient factors, such as body weight, C-reactive protein, and serum albumin concentration, to maintain effective drug concentrations in the serum. Initial studies have found utility for the Bayesian approach in induction and maintenance, in adult and pediatric patients, in clinical trials, and in real-life situations for patients with IBD treated with infliximab. This needs confirmation in larger studies. This article reviews the Bayesian approach to therapeutic drug monitoring in IBD.

The cost of inflammatory bowel disease in high-income settings: a Lancet Gastroenterology & Hepatology Commission

The cost of caring for patients with inflammatory bowel disease (IBD) continues to increase worldwide. The cause is not only a steady increase in the prevalence of Crohn's disease and ulcerative colitis in both developed and newly industrialised countries, but also the chronic nature of the diseases, the need for long-term, often expensive treatments, the use of more intensive disease monitoring strategies, and the effect of the diseases on economic productivity. This Commission draws together a wide range of expertise to discuss the current costs of IBD care, the drivers of increasing costs, and how to deliver affordable care for IBD in the future. The key conclusions are that (1) increases in health-care costs must be evaluated against improved disease management and reductions in indirect costs, and (2) that overarching systems for data interoperability, registries, and big data approaches must be established for continuous assessment of effectiveness, costs, and the cost-effectiveness of care. International collaborations should be sought out to evaluate novel models of care (eg, value-based health care, including integrated health care, and participatory health-care models), as well as to improve the education and training of clinicians, patients, and policy makers.

Early Infliximab Clearance Predicts Remission in Children with Crohn's Disease

BACKGROUND AND AIMS

Children with Crohn's disease have lower response rates to infliximab, lower infliximab levels, and higher infliximab clearance on weight-based dosing than adults. We hypothesize infliximab clearance is a predictive of later outcomes on infliximab in children with Crohn's disease.

METHODS

In this single-center retrospective study, data were collected from charts on diagnosis, anthropometry, routine labs, infliximab therapeutic drug monitoring, infliximab dosing, disease activity, and other treatments. With these data we generated a population pharmacokinetic model using non-linear mixed effects modeling and calculated infliximab clearance for each patient over time. Patients were classified as in remission, responder-only or non-responder at 5, 10 and 16 months. Regression and ROC analyses were used to assess for early predictors of remission and response to infliximab.

RESULTS

Eighty-five subjects were included, with a median follow-up of 22.3 months (IQR 10.1-36.8). Our pharmacokinetic model showed infliximab clearance was positively associated with CRP and weight, while negatively associated with albumin. In regression analyses, early infliximab clearance was the only significant, consistent predictor of remission. A 0.1 L/day increase in infliximab clearance predicted remission with an OR between 0.179 and 0.426. Differences in dosing did not account for differences in outcome. Infliximab clearance alone had moderate predictive accuracy of remission, with an AUC between 0.682 and 0.738.

CONCLUSIONS

Early infliximab clearance is strongly associated with remission in children with Crohn's disease. It may be useful as a marker of response in proactive therapeutic drug monitoring to guide early dose optimization and/or changes in treatment for betterment of long-term outcomes.

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.

Ulcerative Colitis and Acute Severe Ulcerative Colitis Patients Are Overlooked in Infliximab Population Pharmacokinetic Models: Results from a Comprehensive Review

Ulcerative colitis (UC) is part of the inflammatory bowels diseases, and moderate to severe UC patients can be treated with anti-tumour necrosis α monoclonal antibodies, including infliximab (IFX). Even though treatment of UC patients by IFX has been in place for over a decade, many gaps in modelling of IFX PK in this population remain. This is even more true for acute severe UC (ASUC) patients for which early prediction of IFX pharmacokinetic (PK) could highly improve treatment outcome. Thus, this review aims to compile and analyse published population PK models of IFX in UC and ASUC patients, and to assess the current knowledge on disease activity impact on IFX PK. For this, a semi-systematic literature search was conducted, from which 26 publications including a population PK model analysis of UC patients receiving IFX therapy were selected. Amongst those, only four developed a model specifically for UC patients, and only three populations included severe UC patients. Investigations of disease activity impact on PK were reported in only 4 of the 14 models selected. In addition, the lack of reported model codes and assessment of predictive performance make the use of published models in a clinical setting challenging. Thus, more comprehensive investigation of PK in UC and ASUC is needed as well as more adequate reports on developed models and their evaluation in order to apply them in a clinical setting.

Dashboard-Driven Accelerated Infliximab Induction Dosing Increases Infliximab Durability and Reduces Immunogenicity

BACKGROUND AND AIMS

Accelerated infliximab (IFX) induction is often based on clinical parameters as opposed to pharmacokinetics (PK). We aimed to investigate the impact of dashboard-guided optimized induction dosing on IFX durability and immunogenicity in a real-world inflammatory bowel disease (IBD) setting.

METHODS

Pediatric and adult IBD patients were enrolled in a prospective single arm intervention trial. Cumulative data from each infusion (INF), weight, albumin, C-reactive protein, IFX dose, IFX trough level, and antidrug antibody presence were used to inform subsequent INF dosing. Forecasts driven by adaptive Bayesian modeling were generated to maintain trough levels for the third (INF3) and fourth (INF4) infusions of 17 μg/mL and 10 μg/mL, respectively. The primary outcome was proportion of patients prescribed accelerated dosing (AD) intervals by INF3 (<22 days) or INF4 (<49 days). Secondary outcomes included week 52 clinical and PK outcomes. Multivariate analyses and Kaplan-Meier curves compared outcomes based on adherence to dashboard forecasts.

RESULTS

Of the 180 per-protocol population, AD was forecast for 41% (INF3) and 69% (INF4) of patients with median intervals of 17 (INF3) and 39 (INF4) days. Baseline age >18 years, albumin >3.5 g/L, and 10-mg/kg dose were independently associated with lower rates of AD by INF4. Nonadherence with the INF4 forecast (n = 39) was an independent predictor of antidrug antibody (P < .0001) and IFX discontinuation (P = .0006). A total of 119 of 123 patients on IFX at week 52 were in steroid-free remission.

CONCLUSIONS

The application of a PK dashboard during induction can optimize dosing early to improve IFX durability and immunogenicity.

Pharmacokinetics, Pharmacodynamics, and Safety of Etrolizumab in Children With Moderately to Severely Active Ulcerative Colitis or Crohn's Disease: Results from a Phase 1 Randomized Trial

BACKGROUND

Etrolizumab, a humanized anti-β7 antibody, has not been studied in children. Here, we evaluate the pharmacokinetics, pharmacodynamics, and safety of etrolizumab in children with inflammatory bowel disease.

METHODS

Patients age 4 to 17 years with moderately to severely active ulcerative colitis or Crohn's disease were randomized 1:1 to receive 1.5mg/kg of etrolizumab subcutaneously every 4 weeks (q4w) or 3.0mg/kg every 8 weeks (q8w) for 16 weeks in this open-label phase 1 trial. Pharmacokinetics, pharmacodynamics, safety, and efficacy were assessed.

RESULTS

Of the 24 patients treated, 21 completed the study. In the groups of 1.5mg/kg q4w and 3.0mg/kg q8w, respectively, mean (SD) maximum concentration (Cmax) was 9.8 (4.86) µg/mL and 18.1 (6.25) µg/mL; and mean (SD) area under the curve within a dosing interval (AUCtau) was 167 (86.9) and 521 (306) μg·day/mL after the last dose. The Cmax increased dose proportionally. The AUC over an 8-week period was slightly higher in the 3.0mg/kg q8w dose group. Median half-life was similar for both dosing regimens. Median numbers of free β7high gut-homing T and B cell subsets declined below 10% of baseline, confirming β7 target engagement and complete/near-complete receptor occupancy. Adverse events were consistent with the safety profile in adults. Approximately 60% of patients achieved a clinical response.

CONCLUSIONS

Etrolizumab showed a dose-proportional increase in Cmax and a slightly greater than dose-proportional increase in AUCtau. Both regimens achieved complete/near-complete β7 receptor occupancy, with a similar relationship to concentration as adults. Etrolizumab was well tolerated and demonstrated clinical activity in children.

Model Informed Precision Dosing Tool Forecasts Trough Infliximab and Associates with Disease Status and Tumor Necrosis Factor-Alpha Levels of Inflammatory Bowel Diseases

Background: Substantial inter-and intra-individual variability of Infliximab (IFX) pharmacokinetics necessitates tailored dosing approaches. Here, we evaluated the performances of a Model Informed Precision Dosing (MIPD) Tool in forecasting trough Infliximab (IFX) levels in association with disease status and circulating TNF-α in patients with Inflammatory Bowel Diseases (IBD). Methods: Consented patients undergoing every 8-week maintenance therapy with IFX were enrolled. Midcycle specimens were collected, IFX, antibodies to IFX, albumin were determined and analyzed with weight using nonlinear mixed effect models coupled with Bayesian data assimilation to forecast trough levels. Accuracy of forecasted as compared to observed trough IFX levels were evaluated using Demings’s regression. Association between IFX levels, CRP-based clinical remission and TNF-α levels were analyzed using logistic regression and linear mixed effect models. Results: In 41 patients receiving IFX (median dose = 5.3 mg/Kg), median IFX levels decreased from 13.0 to 3.9 µg/mL from mid to end of cycle time points, respectively. Midcycle IFX levels forecasted trough with Deming’s slope = 0.90 and R2 = 0.87. Observed end cycle and forecasted trough levels above 5 µg/mL associated with CRP-based clinical remission (OR = 7.2 CI95%: 1.7−30.2; OR = 21.0 CI95%: 3.4−127.9, respectively) (p < 0.01). Median TNF-α levels increased from 4.6 to 8.0 pg/mL from mid to end of cycle time points, respectively (p < 0.01). CRP and TNF-α levels associated independently and additively to decreased IFX levels (p < 0.01). Conclusions: These data establish the value of our MIPD tool in forecasting trough IFX levels in patients with IBD. Serum TNF-α and CRP are reflective of inflammatory burden which impacts exposure.

Therapeutic Drug Monitoring of Biologics in Crohn's Disease

Reactive therapeutic drug monitoring (TDM) is considered the standard of care for optimizing biologics in inflammatory bowel disease (IBD) including Crohn's disease (CD). Preliminary data show that proactive TDM is associated with positive outcomes in IBD and can be also used to efficiently guide therapeutic decisions in specific clinical scenarios. Higher biological drug concentrations are associated with favorable therapeutic outcomes in specific IBD populations or phenotypes including pediatric CD, perianal fistulizing CD, small bowel CD, and following an ileocolonic resection for CD. Future perspectives of TDM include the use of rapid testing, pharmacogenomics, and pharmacokinetic dashboards toward individualized therapy.

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.

Proactive infliximab optimisation using a pharmacokinetic dashboard versus standard of care in patients with Crohn's disease: study protocol for a randomised, controlled, multicentre, open-label study (the OPTIMIZE trial)

INTRODUCTION

Preliminary data indicates that proactive therapeutic drug monitoring (TDM) is associated with better outcomes compared with empiric dose escalation and/or reactive TDM, and that pharmacokinetic (PK) modelling can improve the precision of individual dosing schedules in Crohn's disease (CD). However, there are no data regarding the utility of a proactive TDM combined PK-dashboard starting early during the induction phase, when disease activity and drug clearance are greatest. The aim of this randomised, controlled, multicentre, open-label trial is to evaluate the efficacy and safety of a proactive TDM combined PK dashboard-driven infliximab dosing compared with standard of care (SOC) dosing in patients with moderately to severely active CD.

METHODS AND ANALYSIS

Eligible adolescent and adult (aged ≥16-80 years) patients with moderately to severely active CD will be randomised 1:1 to receive either infliximab monotherapy with proactive TDM using a PK dashboard (iDose, Projections Research) or SOC infliximab therapy, with or without a concomitant immunomodulator (IMM) (thiopurine or methotrexate) at the discretion of the investigator. The primary outcome of the study is the proportion of subjects with sustained corticosteroid-free clinical remission and no need for rescue therapy from week 14 throughout week 52. Rescue therapy is defined as any IFX dose escalation other than what is forecasted by iDose either done empirically or based on reactive TDM; addition of an IMM after week 2; reintroduction of corticosteroids after initial tapering; switch to another biologic or need for CD-related surgery. The secondary outcomes will include both efficacy and safety end points, such as endoscopic and biological remission, durability of response and CD-related surgery and hospitalisation.

ETHICS AND DISSEMINATION

The protocol has been approved by the Institutional Review Board Committee of the Beth Israel Deaconess Medical Center (IRB#:2021P000391). Results will be disseminated in peer-reviewed journals and presented at scientific meetings.

TRIAL REGISTRATION NUMBER

NCT04835506.

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.

Status Toward the Implementation of Precision Dosing in Children

Precision dosing is progressing beyond the conceptual and proof-of-concept stages toward implementation. As the availability of dosing algorithms, tools, and platforms increases, so do the investment in technology services and actual implementation of clinical services offering these solutions to patients. Nowhere is this needed more than in pediatric populations, which are still reliant on adult drug development and bridging strategies to support dosing, often in the absence of actual dose-finding studies in the target pediatric population. Still, there is more work to be done to ensure that proper governance of these services is maintained, and that sustainability of these early implementations is guided by new science as it evolves and meaningful outcome data to confirm that such services deliver on both clinical and economic return on investment. In addition, the field should ensure that all approaches beyond a therapeutic drug monitoring-driven, pharmacokinetic-centric approach should be considered as the tools and services evolve, especially when pediatric-specific pharmacokinetic/pharmacodyamic and pharmacogenetic data are available and shown to be useful to guide dosing. This review evaluates current pediatric precision dosing efforts, highlighting their utility, longevity, and sustainability and assesses the current process for implementing such approaches examining current barriers that stand in the way of broader implementation and the stakeholders that must engage to ensure its ultimate success.

Pediatric Dose Selection for Therapeutic Proteins

In selecting optimal dosing regimens in support of the clinical use of monoclonal antibodies and other therapeutic proteins in pediatric indications, the unique pharmacokinetic properties of this class of biologics, as well as the underlying physiologic and pathophysiologic processes and their modulation by childhood growth and development, needs to be appreciated. During drug development, first-in-pediatric dose selection is a capstone event in the pediatric investigation plan that relies heavily on extrapolation of pharmacokinetic and pharmacodynamic data from adult to pediatric populations. It is facilitated by combinations of pharmacometric approaches, including allometry, physiologically based pharmacokinetic modeling, and population pharmacokinetic analyses, although data on reliability and qualification of some of these tools in the context of therapeutic proteins are still limited but emerging. Presented data suggest nonlinear relationships between body weight and both clearance and volume of distribution for therapeutic proteins in pediatric populations, with allometric exponents of 0.75 and 0.8, respectively. For newborns and infants (<1 year), even higher nonlinearity seems to occur. Translation of the quantitative characterization of the pediatric pharmacokinetics of therapeutic proteins into dosing regimens for the drug label requires compromising between precision dosing and clinical practicability, with tiered dosing algorithms based on size or age strata being the currently most frequently applied methodology.

Modeling Pharmacokinetics and Pharmacodynamics of Therapeutic Antibodies: Progress, Challenges, and Future Directions

With more than 90 approved drugs by 2020, therapeutic antibodies have played a central role in shifting the treatment landscape of many diseases, including autoimmune disorders and cancers. While showing many therapeutic advantages such as long half-life and highly selective actions, therapeutic antibodies still face many outstanding issues associated with their pharmacokinetics (PK) and pharmacodynamics (PD), including high variabilities, low tissue distributions, poorly-defined PK/PD characteristics for novel antibody formats, and high rates of treatment resistance. We have witnessed many successful cases applying PK/PD modeling to answer critical questions in therapeutic antibodies’ development and regulations. These models have yielded substantial insights into antibody PK/PD properties. This review summarized the progress, challenges, and future directions in modeling antibody PK/PD and highlighted the potential of applying mechanistic models addressing the development questions.

Reinforcement learning and Bayesian data assimilation for model-informed precision dosing in oncology

Model-informed precision dosing (MIPD) using therapeutic drug/biomarker monitoring offers the opportunity to significantly improve the efficacy and safety of drug therapies. Current strategies comprise model-informed dosing tables or are based on maximum a posteriori estimates. These approaches, however, lack a quantification of uncertainty and/or consider only part of the available patient-specific information. We propose three novel approaches for MIPD using Bayesian data assimilation (DA) and/or reinforcement learning (RL) to control neutropenia, the major dose-limiting side effect in anticancer chemotherapy. These approaches have the potential to substantially reduce the incidence of life-threatening grade 4 and subtherapeutic grade 0 neutropenia compared with existing approaches. We further show that RL allows to gain further insights by identifying patient factors that drive dose decisions. Due to its flexibility, the proposed combined DA-RL approach can easily be extended to integrate multiple end points or patient-reported outcomes, thereby promising important benefits for future personalized therapies.

Early Inflammatory Markers are Associated With Inadequate Post-Induction Infliximab Trough in Pediatric Crohn's Disease

OBJECTIVES

In pediatric Crohn's disease, infliximab trough concentrations after standard weight-based induction therapy are commonly below 7 μg/mL. Clinical treatment outcomes are associated with post-induction infliximab trough concentration. Markers of inflammation are associated with low infliximab concentrations during maintenance dosing. We sought to determine if early markers of disease activity are associated with inadequate post-induction infliximab trough concentrations in pediatric Crohn's disease.

METHODS

We performed a retrospective single-center case-control study of pediatric Crohn's disease patients to assess the association between baseline and week-2 biomarkers (albumin, C-reactive protein, and erythrocyte sedimentation rate) and inadequate post-induction infliximab trough concentration (<7 μg/mL) in patients treated with standard 5 mg/kg dosing. Baseline and week-2 biomarker values were coded as dichotomous variables at clinically useful thresholds. Univariable logistic regression was used to calculate odds ratios of developing an inadequate infliximab trough concentration for each threshold, as well as thresholds in combination.

RESULTS

Fifty-five patients were evaluated. Early biomarker thresholds significantly associated with inadequate post-induction infliximab trough concentrations included baseline C-reactive protein >1 mg/dL (odds ratio [OR] 4.58; 95% confidence interval [CI] 1.24--17.01), both baseline C-reactive protein >0.5 mg/dL and albumin <3.5 g/dL (OR 8.31; 95% CI 1.99--34.63), and week-2 C-reactive protein >0.5 mg/dL or albumin <3.5 mg/dL or erythrocyte sedimentation rate >25 mm/hour (OR 11.08; 95% CI 2.14--57.22).

CONCLUSIONS

Routine baseline and week-2 markers of disease activity at clinically useful thresholds were associated with inadequate post-induction infliximab trough concentration in pediatric Crohn's disease patients receiving standard weight-based induction dosing.

Efficacy of dashboard driven dosing of infliximab in inflammatory bowel disease patients; a randomized controlled trial

OBJECTIVES

Loss of response (LOR) to infliximab (IFX) remains a challenge in the management of inflammatory bowel diseases (IBD). Proactive dosing strategies to achieve and maintain predefined IFX trough levels (TL) may prevent LOR. We aimed to investigate the efficacy of dashboard driven IFX dosing compared to standard dosing in a prospective trial in IBD patients.

METHODS

In this multicentre 1:1 'PRECISION' trial, we randomized IBD patients in clinical remission (Harvey Bradshaw Index ≤4 for Crohn's disease (CD) or a partial Mayo score ≤2 for ulcerative colitis (UC)) receiving IFX maintenance treatment. The precision group (PG) received IFX dosing guided by a Bayesian pharmacokinetic model, aiming to achieve and maintain a TL of 3 µg/ml by treatment (de)escalation as indicated by the dashboard. Patients in the control group (CG) continued treatment without dose adaptations. The primary endpoint was the proportion of patients in sustained clinical remission after 1 year.

RESULTS

Eighty patients were enrolled (66 CD, 14 UC), and the median [interquartile range] age was 37 years [27-51]). After one year, 28/32 (88%) of patients in the PG were in sustained clinical remission versus 25/39 (64%) in the CG (p = .017). PG patients had lower median faecal calprotectin levels after 1 year (p = .031), whereas no significant differences in median CRP levels were found.

CONCLUSION

We demonstrated that the use of a Bayesian dashboard for IFX dosing in maintenance treatment for IBD reduced the incidence of LOR compared to standard dosing. Precision dosing also resulted in lower FCP levels.

CLINICALTRIALS.GOV NUMBER

NCT02453776.

Advances in Therapeutic Drug Monitoring in Biologic Therapies for Pediatric Inflammatory Bowel Disease

In the current era of treat-to-target strategies, therapeutic drug monitoring (TDM) has emerged as a potential tool in optimizing the efficacy of biologics for children diagnosed with inflammatory bowel disease (IBD). The incorporation of TDM into treatment algorithms, however, has proven to be complex. "Proactive" TDM is emerging as a therapeutic strategy due to a recently published pediatric RCT showing a clear benefit of "proactive" TDM in anti-TNF therapy. However, target therapeutic values for different biologics for different disease states [ulcerative colitis (UC) vs. Crohn's disease (CD)] and different periods of disease activity (induction vs. remission) require further definition. This is especially true in pediatrics where the therapeutic armamentarium is limited, and fixed weight-based dosing may predispose to increased clearance leading to decreased drug exposure and subsequent loss of response (pharmacokinetic and/or immunogenic). Model-based dosing for biologics offers an exciting insight into dose individualization thereby minimizing the chances of losing response. Similarly, point-of-care testing promises real-time assessment of drug levels and individualized decision-making. In the current clinical realm, TDM is being used to prolong drug durability and efficacy and prevent loss of response. Ongoing innovations may transform it into a personalized tool to achieve optimal therapeutic endpoints.

A Critique of Pharmacokinetic Calculators for Drug Dosing Individualization

The 'one-dose-fits-all' approach where drug dosing regimen is prescribed according to recommendations from a summary of product characteristics is not appropriate for many patients whose clinical characteristics significantly differ from the most frequent ones in a population, as it cannot guarantee optimal exposure of target tissues to the drug. Our aim here is to provide a concise review of pharmacokinetic calculators currently available for clinical use and, at the same time, to suggest the minimum standards that they should satisfy to be routinely used in clinical practice. A systematic search of Medline, Ebsco, Scopus, Scindeks, Cochrane Library and Google Scholar was performed to find publications about available pharmacokinetic calculators for drug dose individualization. Theoretically well-founded and mathematically correct calculators for many drugs are available, but only a few calculators for specific drugs have been validated in clinical practice or through clinical trials, and the results published in peer-reviewed journals. The majority of available pharmacokinetic calculators for drug dosing individualization remain unvalidated, i.e., there is no evidence of their efficacy and safety in real-life clinical settings. Pharmacokinetic calculators for drug dose individualization are irreplaceable tools for achieving precision medicine, where dosing regimens are tailored to the needs and personal characteristics of each patient, maximizing efficacy and minimizing toxicity.

Monitoring vedolizumab and ustekinumab drug levels in patients with inflammatory bowel disease: hype or hope?

Therapeutic drug monitoring (TDM) plays a vital role in implementing precision medicine in inflammatory bowel disease (IBD), and may contribute to increased effectiveness, lower rates of drug toxicity and cost savings. While expert panels advocate the use of reactive TDM for anti-tumor necrosis factor (anti-TNF) agents, TDM is not yet widely recommended for non-anti TNF biologicals. We provide an overview of the observational evidence of the value of TDM in case of vedolizumab and ustekinumab. We also shed light on obstacles that need to be addressed before establishing wide acceptance of TDM in the field of IBD. In this respect, new analytical techniques and modelling approaches are being developed to further optimize efficacy of TDM and to facilitate general acceptance of this tool in personalizing IBD management.

Optimization of infliximab therapy in inflammatory bowel disease using a dashboard approach-an Indian experience

PURPOSE

Infliximab (IFX) therapy in inflammatory bowel disease (IBD) is associated with loss of response in half the patients, due to complex pharmacokinetic and immunological factors. Dashboard's Bayesian algorithms use information from model and individual multivariate determinants of IFX concentration and can predict dose and dosing interval.

AIM

To compare measured IFX concentrations in our laboratory with values predicted by iDose dashboard system and report its efficacy in managing patients not responding to conventional dosing schedule.

METHOD

Clinical history, demographic details, and laboratory findings such as albumin and C-reactive protein (CRP) data of IBD patients (n = 30; median age 23 years (IQR: 14.25 - 33.5)) referred for IFX drug monitoring in our laboratory from November 2017 to November 2019 were entered in iDose software. The IFX concentration predicted by iDose based on this information was compared with that measured in our laboratory. In addition, a prospective dashboard-guided dosing was prescribed in 11 of these 30 patients not responding to conventional dosing and was followed to assess their clinical outcome.

RESULT

IFX monitoring in our 30 patients had shown therapeutic concentration in 12, supratherapeutic in 2 and subtherapeutic concentration in 16 patients. The iDose predicted concentration showed concordance in 21 of these 30 patients. Of 11 patients managed with iDose-assisted prospective dosing, 8 achieved clinical remission, 2 showed partial response, and one developed antibodies.

CONCLUSION

Retrospective data analysis showed concordance between laboratory measured and iDose-predicted IFX level in 70% of patients. iDose-assisted management achieved clinical remission and cost reduction.

Evaluation of dose-tapering strategies for intravenous tocilizumab in rheumatoid arthritis patients using model-based pharmacokinetic/pharmacodynamic simulations

PURPOSE

Tocilizumab is a humanized monoclonal antibody approved for rheumatoid arthritis treatment. In clinical practice, empirical dose-tapering strategies are implemented in patients showing sustained remission or low disease activity (LDA) to avoid overtreatment and reduce costs. Since rational adaptive-dosing algorithms taking the full pharmacokinetic (PK)/pharmacodynamic (PD) characteristics into account are currently lacking, we aimed to develop novel tapering strategies and compare them with currently used empirical ones.

METHODS

Four strategies were simulated on a virtual population. In all of them, the same initial dose was administered every 28 days for six consecutive months. Then, different strategies were considered: (1) label-dosing; (2) mild empirical dose-tapering; (3) intense empirical dose-tapering; (4) therapeutic drug monitoring (TDM)-guided dose-tapering. The different strategies were evaluated on the proportion of patients who maintain remission/LDA 1 year after the intervention. Cost-savings of direct drug costs were also estimated as relative dose intensity.

RESULTS

The overall proportion of simulated patients in remission/LDA after 1 year of the intervention was comparable between the mild empirical and the TDM-guided dose-tapering strategies, and much lower for the intense empirical dose-tapering strategy (80.3%, 78.2%, and 69.0%, respectively). Likewise, 1-year flare rates were lower for the mild empirical and TDM-guided tapering strategies. The relative dose intensity was lowest for the intense empirical dose-tapering, followed by the TDM-guided and the mild empirical dose-tapering approaches (61.2%, 71.0%, and 80.4%, respectively).

CONCLUSION

We demonstrated that the TDM-guided strategy using model-based algorithms performed similarly to mild empirical dose-tapering strategies in overall remission/LDA rates but is superior in cost-savings.

Pharmacokinetics, Pharmacodynamics, and Immunogenicity of Infliximab in Pediatric Inflammatory Bowel Disease: A Systematic Review and Revised Dosing Considerations

OBJECTIVES

Infliximab (IFX), a monoclonal antibody directed against tumor necrosis factor alpha is a potent treatment option for inflammatory bowel disease (IBD). Dosing regimens in children are extrapolated from adult data using a fixed, weight-based dose, which is often not adequate. While clinical trials have focused on safety and efficacy, there is limited data on pharmacokinetic characteristics and immunogenicity of IFX in children. The objective was to provide a systematic overview of current literature on pharmacokinetic and immunogenicity of IFX in children with IBD, to assess the validity of current adult to pediatric dosing extrapolation.

METHODS

A literature search identified publications up to October 2018. Eligibility criteria were study population consisting of children and/or adolescents with IBD, report of IFX trough levels and/or antibodies-to IFX, full text article or abstract, article in English, and original data.

RESULTS

Initial electronic search yielded 2360 potentially relevant articles, with 1831 remaining after removal of duplicates. An additional search yielded another 202 potentially relevant articles. Of the 2033 retrieved articles, 2000 articles were excluded based on title, abstract, or eligibility criteria. Clearance of IFX was increased in young children and children with extensive disease, leading to lower trough levels after extrapolated dosing of 5 mg/kg, antibodies-to IFX emergence, and subsequent reduced efficacy.

CONCLUSIONS

Adult to pediatric weight-based dosing extrapolation is often inadequate. We provide several considerations for optimal dosing of IFX in children and adolescents with IBD.

How, When, and for Whom Should We Perform Therapeutic Drug Monitoring?

The implementation of therapeutic drug monitoring (TDM) in the inflammatory bowel disease practice has evolved over the years. In the early days, the focus was merely on measuring and reporting drug concentrations. Later, these concentrations were considered in light of target concentrations that are related to clinical response. This not only allowed passively predicting a patient's future response, but it also triggered physicians and pharmacists to actively use the information to optimize the drug dosage to induce and maintain a clinical response in the future. Although reactive TDM, testing at time of loss of response, is widely accepted in practice, especially for anti-tumor necrosis factor antibodies, there are less data for the other monoclonal antibodies belonging to other classes. Besides reactive testing, there is a movement toward proactively adjusting biologic dosing to prevent loss of response, in keeping with the tight control philosophy of inflammatory bowel disease care. This review highlights the various assays available to measure drug concentrations and antidrug antibodies, as well as algorithmic approaches to TDM, the unmet needs and required studies to enable pharmacokinetics principles to be applied in the future.

An Indian national survey of therapeutic drug monitoring with anti-tumor necrosis (TNF) medications in inflammatory bowel disease

BACKGROUND

Evidence supports therapeutic drug monitoring (TDM) in improving efficacy and cost-effectiveness of anti-TNF therapy in inflammatory bowel disease (IBD). Data on perceptions and barriers to TDM use are limited and no data are available from India. Our objective was to assess clinicians' attitudes and barriers to TDM use in IBD.

METHODS

A 16-question survey was distributed to members of the Indian Society of Gastroenterology. Information on clinician characteristics, demographics, use and barriers towards TDM with anti-TNFs was collected. Logistic regression was used to predict factors influencing TDM use.

RESULTS

Two hundred and forty-two respondents participated (92.5% male); 83% were consultant gastroenterologists. Of 104 respondents meeting inclusion criteria (treating > 5 IBD patients and at least 1 with an anti-TNF per month), complete responses were available for 101 participants. TDM was utilized by 20% (n = 20) of respondents. Of them, 89.5% (n = 17) used TDM for secondary loss of response; 73.7% (n = 14) for primary non-response and 5.3% (n = 1) proactively. Barriers to TDM use were cost (71.2%), availability (67.8%), time lag in results (58.7%) and the perception that TDM is time-consuming (45.7%). Clinicians treating > 30 IBD patients were more likely to check TDM (OR = 4.9, p = 0.02). Of 81 respondents not using TDM, 97.5% (n = 79) would do so if all the barriers were removed.

CONCLUSION

Significant barriers to TDM use were availability, cost and time lag for results. If these barriers were removed, almost all the clinicians would use TDM at least reactively and 25% would use proactively. There is an urgent need to address these barriers and optimize anti-TNF therapy for optimal outcomes.

Improved Population Pharmacokinetic Model for Predicting Optimized Infliximab Exposure in Pediatric Inflammatory Bowel Disease

BACKGROUND

Many pediatric patients with inflammatory bowel disease (IBD) lose response to infliximab (IFX) within the first year, and achieving a minimal target IFX trough concentration is associated with higher remission rates and longer durability. Population pharmacokinetic (PK) modeling can predict trough concentrations for individualized dosing. The object of this study was to refine a population PK model that accurately predicts individual IFX exposure during maintenance therapy using longitudinal real-practice data.

METHODS

We exported data from the electronic health records of pediatric patients with IBD treated with originator IFX at a single center between January 2011 and March 2017. Subjects were divided into discovery and validation cohorts. A population PK model was built and then validated.

RESULTS

We identified 228 pediatric patients with IBD who received IFX and had at least 1 drug concentration measured, including 135 and 93 patients in the discovery and validation cohorts, respectively. Weight, albumin, antibodies to IFX (ATI) detected by a drug-tolerant assay, and erythrocyte sedimentation rate (ESR) were identified as covariates significantly associated with IFX clearance and incorporated into the model. The model exhibited high accuracy for predicting target IFX trough concentrations with an area under the receiver operating characteristic curve (AUROC) of 0.86 (95% confidence interval [CI], 0.81-0.91) for population-based predictions without prior drug-level input. Accuracy increased further for individual-based predictions when prior drug levels were known, with an AUROC of 0.93 (95% CI, 0.90-0.97).

CONCLUSIONS

A population PK model utilizing weight, albumin, ordinal drug-tolerant ATI, and ESR accurately predicts IFX trough concentrations during maintenance therapy in real-practice pediatric patients with IBD. This model, which incorporates dynamic clinical information, could be used for individualized dosing decisions to increase response durability.

UK National Survey of Gastroenterologists' attitudes and barriers toward therapeutic drug monitoring of anti-TNF therapy in inflammatory bowel disease

BACKGROUND

Evidence supports use of therapeutic drug monitoring (TDM) in improving efficacy and cost-effectiveness of anti-tumour necrosis factor (TNF) therapy in inflammatory bowel disease (IBD). Our objective was to assess attitudes and barriers towards TDM use with anti-TNF's in the UK.

METHODS

A 17-question survey was distributed to members of the British Society of Gastroenterology by email.

RESULTS

Of 243 respondents (51.6% male), 237 respondents met inclusion criteria. Of these, 46% were consultants (gastroenterologist, GI), 39.2% IBD nurse specialists (clinical nurse specialists, CNS), 14.8% registrars. TDM is used by 96.9% for secondary loss of response; 72.5% for primary non-response and 54.1% used TDM proactively. Barriers were time lag in receiving results (49.8%), lack of awareness of guidelines (46.4%) and cost (29.9%). Clinicians working at a teaching hospital (OR 2.6, 95% CI 0.71 to 9.8), IBD CNS and GI registrars (OR 2.6, 95% CI 0.7 to 10 and OR 1.5, 95% CI 0.3 to 7.2, respectively) were more likely to use TDM. Clinicians practising for >20 years (OR 4.1, 95% CI 0.4 to 41.8) and a large volume IBD practice (>50% IBD patients per month) were more likely to use TDM (OR 45.7, 95% CI 7.5 to 275). Proactive TDM, was more likely to be used in tertiary care (OR 2.25, 95% CI 0.84 to 6.1), IBD CNS (OR 1.2, 95% CI 0.7 to 2.1) and clinicians managing >50% IBD patients per month (OR 10.8, 95% CI 1.3 to 90.3). Clinicians with 5-9 years of experience in practice were more likely to use proactive TDM (OR 2.6 and CI 1.04 to 6.4).

CONCLUSION

Validation of point of care and lower cost assays, reduced time lag from test to result, lower cost of testing and dissemination of current recommendations may further optimise treatment strategies.

Therapeutic Drug Monitoring and Outcome of Infliximab Therapy in Pediatric Onset Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) with pediatric onset has become more prevalent during past decades. Thus, the number of patients with moderate to severe disease subtype treated with antagonists to tumor necrosis factor alpha (TNFα) has concurrently risen. Most pediatric patients initially respond to these drugs but will need dose escalation during the first year of therapy. As pediatric data regarding therapeutic drug monitoring during therapy with TNFα-blocker adalimumab are sparse, this review focuses on the literature on therapeutic drug monitoring of infliximab and how it may guide management.

Effectiveness of long-term infliximab use and impact of treatment adherence on disease control in refractory, non-infectious pediatric uveitis

BACKGROUND

Refractory non-infectious uveitis is a serious condition that leads to ocular complications and vision loss and requires effective systemic treatment to control disease. The effectiveness of long-term infliximab [IFX] in refractory non-infectious childhood uveitis and the impact of treatment adherence on disease control were evaluated.

METHODS

Retrospective, single-center study between December 2002 and April 2016 of 27 children with refractory non-infectious uveitis [17 with juvenile idiopathic arthritis, JIA] treated with long-term IFX [9+ months]. Disease activity was assessed prior to and while on IFX using the Standardization of Uveitis Nomenclature [SUN]. Number of visits per year with active uveitis was analyzed by repeated measures logistic regression analysis from 2 years prior to IFX initiation or from onset of uveitis until most recent visit on IFX. Incomplete treatment adherence was assessed for each visit and defined as any deviance in corticosteroid use, prescribed infusion frequency, and/or follow-up examination frequency.

RESULTS

Primary outcomes were sustained uveitic and systemic disease control prior to and during IFX treatment and the impact of incomplete adherence on uveitic disease control while on IFX. Secondary outcomes included corticosteroid and glaucoma medication requirement, ocular complications and need for surgical intervention. Mean age at IFX initiation was 10.4 ± 4.5 years; initial mean dose was 6.6 ± 2.2 mg/kg [and given at weeks 0, 2, 4 and q4 weeks thereafter for 93%]. Median duration on IFX was 35 [range 9-128] months. Prior to IFX, 14/27 patients had failed adalimumab ± methotrexate [MTX]; 21/27 failed MTX. IFX led to uveitis control in 89% and arthritis control in 76% (13/17). The odds ratio of having controlled disease after IFX was 4.1 (2.6, 6.4) compared to pre-treatment visits. Topical corticosteroids and glaucoma medications were statistically decreased (p = 0.007 right eye [OD], 0.003 left eye [OS] and p = 0.001 OD, p = 0.028 OS respectively). Incomplete adherence to treatment showed 10.3 times greater odds (7.1, 15.0) of having disease activity than full adherence.

CONCLUSIONS

This study adds significantly to the IFX literature by documenting outstanding uveitis control with long-term IFX treatment in non-infectious pediatric uveitis patients. Higher dosage and shorter interval were utilized without adverse effects. Importantly, this is the first study, to our knowledge, to document the significant impact of treatment adherence on uveitis control.

Therapeutic drug monitoring-based dosing of TNF inhibitors in inflammatory bowel disease: the way forward?

Introduction: Secondary loss of response to anti-tumor necrosis factor (TNF) therapy remains a challenge in the clinical management of inflammatory bowel disease (IBD) patients. A frequently observed reason for secondary loss of response to TNF blockers is inadequate drug exposure and sub-therapeutic serum drug concentrations. Areas covered: This review presents an overview of recent research on therapeutic drug monitoring (TDM)-based dosing with anti-TNF agents in IBD. The role of reactive and proactive TDM and different approaches on how to optimize anti-TNF treatment are discussed. Expert opinion: Due to variations within and between patients, the 'one size fits all' theory does not apply to all IBD patients receiving anti-TNF agents. Timing of TDM (i.e. reactive versus proactive) is a matter of debate. Both strategies might optimize anti-TNF treatment, although most trials did not show a clinical benefit compared to conventional dosing up to now. So-called dashboard systems might have an additive value in the optimization of anti-TNF treatment, since these tools enable clinicians to really personalize anti-TNF treatment.

Therapeutics for Inflammatory Bowel Diseases in Children and Adolescents: A Focus on Biologics and an Individualized Treatment Paradigm

Pharmacologic treatment of children and adolescents with inflammatory bowel diseases (IBD) [Crohn's disease and ulcerative colitis] requires consideration of disease and medication effects on growth and nutrition, the importance of durability of biologics, and concerns for long-term sequelae of disease and therapies. Achieving early remission in children with Crohn's disease correlates with improved outcomes and therefore allows a window of opportunity for maximizing growth. Thus, there is a great need to treat children and adolescents with the right drug at the right time while achieving adequate exposure. Improved understanding of disease phenotypes, disease natural history, and risk stratification will play a critical role in treatment selection for children, particularly as more therapeutic options become available. Here we summarize data supporting newer concepts of treating the individual child with IBD through targeted early biologic treatment, including utilization of therapeutic drug monitoring to optimize treatment effects and the use of early antitumor necrosis factor (TNF)-α therapies to mitigate long-term sequelae of the disease. Recent inception cohort studies provide important data regarding the risk stratification of children and adolescents with IBD, which support a move toward a personalized therapeutic approach to IBD in children and adolescents.

'Quality of Care' Standards in Inflammatory Bowel Disease: A Systematic Review

BACKGROUND

Inflammatory bowel disease [IBD] includes chronic, disabling and progressive conditions that need a complex approach and management. Although several attempts have been made to standardize the care of IBD patients, no clear definitions of a global 'standard of care' are currently available.

METHODS

We performed a systematic review of the available literature, searching for all relevant data concerning three main domains of standards of quality of care in IBD patients: structure, process and outcomes. From the literature search, 2394 abstracts were retrieved, and 62 relevant papers were included in the final review.

RESULTS

Standards of quality of care in IBD include several aspects that can be summarized in three identified domains: structure, process and outcomes. The suggested structure of an IBD Unit includes a multi-disciplinary approach, effective referral processes, improved access using helplines, and departmental guidelines/pathways with identification of measurable quality indicators. Coordinated care models which incorporate a multi-disciplinary approach, structured clinical pathways or processes for the diagnosis, monitoring and treatment of IBD, fast-track recovery from IBD surgery, designated IBD clinics, virtual clinics and telemanagement are currently considered the main standards for process, although supporting data are limited. Several consensus statements on outcomes and quality indicators have been reported, focusing on outcomes in symptoms, function and quality of life restoration, survival and disease control, in addition to effective healthcare utilization.

CONCLUSIONS

The results of this systematic review can provide the basis for general recommendations for standards of quality of care in IBD.