Serum trough infliximab levels: A comparison of three different immunoassays for the monitoring of CT-P13 (infliximab) treatment in patients with inflammatory bowel disease

Comparison of SB2-Infliximab With Originator-Infliximab in the Measurement of Serum Concentrations: A Short Communication

BACKGROUND

The optimal use of infliximab depends on the measurement of trough levels with subsequent appropriate dose adjustment. With the introduction of biosimilars, it is important to demonstrate that the biosimilar behaves similarly in the assay used as the originator-infliximab, for which the assays were developed. In this study, the authors aimed to compare the concentrations of SB2-infliximab (Renflexis) with that of originator-infliximab (Remicade) when added to serum from healthy subjects and those with inflammatory bowel disease when measured by commonly used commercial assays.

METHODS

Sera from 2 healthy controls, 2 patients with ulcerative colitis (1 with quiescent disease and 1 with active disease), and 2 patients with Crohn disease (1 with quiescent disease and 1 with active disease) were spiked with SB2-infliximab or originator-infliximab at 0-20 mcg/mL. Concentrations were measured using 3 commonly used assay kits (Lisa-Tracker, Shikari Q-Inflix, Promonitor IFX) and one rapid test (Quantum Blue). The results were compared using Bland-Altman techniques.

RESULTS

Close agreement was observed between measured concentrations for all assays, irrespective of the origin of the serum. Limits of agreement varied between at worst -0.302 and 0.465 mcg/mL, with the mean difference between the molecules being at worst 0.04 mcg/mL (95% confidence intervals, -0.011 to 0.093).

CONCLUSIONS

The originator and SB-2 biosimilar-infliximab behaved similarly in several currently used assays in their concentrations in biological fluids. Clinicians can be confident that therapeutic drug monitoring using platforms designed and developed for the originator-infliximab can be applied to SB-2-infliximab.

Comparison of three immunoassays for infliximab trough level monitoring in paediatric inflammatory bowel diseases

Many clinical studies in paediatric inflammatory bowel diseases (IBD) use infliximab trough level (IFX-TL) and detection of antibody against infliximab (ATI). Hence, comparison of commercially available assays is needed in paediatric samples to assess their reliability and their comparability. We measured IFX-TL and ATI-TL in sera samples of 53 IBD children using three ELISA kits: Lisa-Tracker® Duo Infliximab (Theradiag®), Ridascreen® IFX monitoring (R-Biopharm®) and Promonitor® IFX (Grifols®). Regarding IFX-TL, median values were comparable (p > 0.05), a good statistical correlation has been observed (0.73 ≤ R² ≤ 0.85) between tested assays and the Bland-Altman analysis found an excellent agreement with a bias estimated between -0.56 and 0.12 and few values outside the 95% limits of agreement. However, qualitative comparison with therapeutic interval classifications showed some discrepancies (30.2%), mainly due to values near thresholds and more often than not with Theradiag® (22.6%). For ATI, because of non-standardized units, the qualitative comparison found a sensibly good agreement (98.1%). These data show a good agreement of IFX-TL and ATI measurement between three marketed ELISA assays with a small bias obtained. Variations in some results can lead to divergent therapeutic interval classifications and prompt us to be cautious in the interpretation of values near therapeutic thresholds.

Infliximab, adalimumab and vedolizumab concentrations across pregnancy and vedolizumab concentrations in infants following intrauterine exposure

BACKGROUND

The impact of pregnancy on levels of biologic agents in patients with IBD is undefined and time to elimination in vedolizumab-exposed infants is unknown.

AIMS

To determine the effect of pregnancy on infliximab, adalimumab and vedolizumab levels and to study infant vedolizumab clearance METHODS: In a prospective observational study, maternal drug levels were measured pre-conception, in each trimester, at delivery and postpartum. The association between drug levels and gestation in weeks was assessed using generalised estimating equation modelling. Infant vedolizumab levels were performed at birth (cord blood), 6 weeks and 3 months or until undetectable.

RESULTS

We included 50 IBD patients (23 on infliximab, 15 on adalimumab and 12 on vedolizumab) with at least two intrapartum observations, plus 5 patients on vedolizumab with only mother and baby samples at delivery. Modelling showed no change in adalimumab levels, an increase in infliximab levels of 0.16 (95% CI 0.08-0.24) µg/L/week (P < 0.001) and a decrease of 0.18 (95% CI: -0.33 to -0.02) µg/L/week (P = 0.03) for vedolizumab. In 17 mother-baby pairs, median infant vedolizumab levels at birth were lower than maternal levels (P < 0.05) with an infant:maternal ratio of 0.7 (IQR 0.5-0.9). Vedolizumab was undetectable between 15 and 16 weeks of age in all 12 infants completing follow-up testing.

CONCLUSIONS

During pregnancy, adalimumab levels remain stable, while infliximab levels increase and vedolizumab levels decrease. However, the increments were small suggesting that intrapartum therapeutic drug monitoring and dose adjustment are not indicated. Unlike infliximab and adalimumab, infant vedolizumab levels are lower in cord blood than in mothers and appear to clear rapidly.

Laboratory Monitoring of Biological Therapies in Rheumatology: The Role of Immunogenicity

Biological drugs, such as proteins and immunogens, are increasingly used to treat various diseases, including tumors and autoimmune diseases, and biological molecules have almost completely replaced synthetic drugs in rheumatology. Although biological treatments such as anti-tumor necrosis factor (TNF) drugs seem to be quite safe, they cause some undesirable effects, such as the onset of infections due to weakening of the immune system. Given the biological nature of these drugs, they might be recognized as extraneous; this would induce an immune reaction that neutralizes their effectiveness or lead to more serious consequences. Laboratories play a pivotal role in appropriate therapeutic management. The aim of this review was to underline the production of anti-drug antibodies during treatment with biological drugs and highlight the role of laboratories in ensuring appropriate use of these drugs.

An in vitro comparison of four different immunoassays for the monitoring of Infliximab biosimilars drug levels

BACKGROUND

SB2 (Renflexis®, Merck) and CT-P13 (Inflectra®, Pfizer) are biosimilars of the reference Infliximab (Remicade®, Janssen) and are approved in Canada for use in indications for which Infliximab is approved, including inflammatory bowel disease. These biosimilars are structurally different but exhibit comparable physicochemical characteristics, pharmaceutical effectiveness and immunogenicity compared to Infliximab. Optimal Infliximab therapy currently relies on therapeutic drug monitoring offered by several reference laboratories.

OBJECTIVE

Because the appropriate dosing depends on accurate determination of drug levels and anti-drug antibodies, the ability of current Infliximab assays to measure the biosimilars and corresponding antibodies needs to be demonstrated.

METHODS

The correlation between Infliximab and the biosimilars measured with four different enzyme-linked immunosorbent assays for Infliximab detection was evaluated. Spiked serum samples were assayed with kits from (A) Immunodiagnostik/ALPCO Diagnostics, (B) R-Biopharm, (C) Theradiag and (D) Progenika Biopharma. The impact of various concentrations of antibodies to Infliximab on the quantification of biosimilars was also tested.

RESULTS

A good correlation of SB2, CT-P13 and reference Infliximab spiked serum samples was observed with the four assays. The observed bias between the original drug and biosimilars is clinically insignificant and less than the usual analytical variability observed with these methods. The quantification of the biosimilars and Infliximab was equally impacted in serums containing antibodies to Infliximab. The recovery of the drugs was inversely correlated with the concentration of anti-Infliximab antibodies, suggesting common immunodominant epitopes for SB2, CT-P13 and Infliximab.

CONCLUSION

The ability of these assays to properly quantify the biosimilars Renflexis® and Inflectra® has been demonstrated. The therapeutic drug monitoring required for Infliximab therapy can be adequately performed with the biosimilars using the kits currently in use or available in clinical laboratories.

Infliximab in young paediatric IBD patients: it is all about the dosing

Infliximab (IFX) is administered intravenously using weight-based dosing (5 mg/kg) in inflammatory bowel disease (IBD) patients. Our hypothesis is that especially young children need a more intensive treatment regimen than the current weight-based dose administration. We aimed to assess IFX pharmacokinetics (PK), based on existing therapeutic drug monitoring (TDM) data in IBD patients < 10 years. TDM data were collected retrospectively in 14 centres. Children treated with IFX were included if IFX was started as IBD treatment at age < 10 years (young patients, YP) and PK data were available. Older IBD patients aged 10-18 years were used as controls (older patients, OP). Two hundred and fifteen paediatric inflammatory bowel disease (PIBD) patients were eligible for the study (110 < 10 year; 105 ≥ 10 years). Median age was 8.3 years (IQR 6.9-8.9) in YP compared with 14.3 years (IQR 12.8-15.6) in OP at the start of IFX. At the start of maintenance treatment, 72% of YP had trough levels below therapeutic range (< 5.4 μg/mL). After 1 year of scheduled IFX maintenance treatment, YP required a significantly higher dose per 8 weeks compared with OP (YP; 9.0 mg/kg (IQR 5.0-12.9) vs. OP; 5.5 mg/kg (IQR 5.0-9.3); p < 0.001). The chance to develop antibodies to infliximab was relatively lower in OP than YP (0.329 (95% CI - 1.2 to - 1.01); p < 0.001), while the overall duration of response to IFX was not significantly different (after 2 years 53% (n = 29) in YP vs. 58% (n = 45) in OP; p = 0.56).Conclusion: Intensification of the induction scheme is suggested for PIBD patients aged < 10 years. What is Known? •Infliximab trough levels of paediatric IBD patients are influenced by several factors as dosing scheme, antibodies and inflammatory markers. •In 4.5-30% of the paediatric IBD patients, infliximab treatment was stopped within the first year. What is New? •The majority of young PIBD (< 10 years) have inadequate IFX trough levels at the start of maintenance treatment. •Young PIBD patients (< 10 years) were in need of a more intensive treatment regimen compared with older paediatric patients during 1 year of IFX treatment. •The chance to develop antibodies to infliximab was relatively higher in young PIBD patients (< 10 years).

Assays used to assess biosimilarity of therapies for inflammatory bowel disease

Introduction: Biological drugs have revolutionized the treatment of various medical conditions. Recently, upon expiration of patents of a few biological agents, biosimilars are being rapidly developed as an affordable substitute for more expensive biologic drugs, which may serve as a therapeutic alternative for biologics reference medical product (RMP). Prior to approval for use of the biosimilar drug for treatment of RMP indications, a process involving several different assays is required, in which the biosimilar must prove to posses no meaningful differences from an existing approved RMP in terms of purity, safety and potency.Areas covered: This report describes the different assays which are used to assess biosimilar drugs using CT-P13 infliximab biosimilar as a case-in-point. It covers the assays of physicochemical characterization, biological activity, and immunogenicity and examines their rational along with methodological and conceptual caveats clinicians should be cognizant of.Expert opinion: The approval of a biosimilar is a complex process that requires several assays, specifically tailored to the characteristics of the RMP. Determining the required assays and the allowable margin of confidence are of great importance but are not sufficient in order to prove that the biosimilar is indeed not inferior in its clinical potency and safety to the RMP.

Outcomes of Patients With Inflammatory Bowel Diseases Switched From Maintenance Therapy With a Biosimilar to Remicade

BACKGROUND & AIMS

There is evidence that it is safe and effective for patients with inflammatory bowel diseases (IBD) to switch from maintenance therapy with an original infliximab drug to a biosimilar, but little is known about outcomes of reverse switches and/or multiple switches. We aimed to evaluate the effects of a reverse switch (from a biosimilar to Remicade) in a real-life cohort.

METHODS

We performed a prospective observational study of 174 unselected and consecutive patients with IBD (136 with Crohn's disease [CD] and 38 with ulcerative colitis [UC]) who received maintenance therapy with the biosimilar in Hungary. In September 2017, patients were switched from the biosimilar (CT-P13) to Remicade, due to reimbursement policies. In our cohort, 8% (n = 14) patients had been previously exposed to the originator Remicade. We collected clinical and biochemical information from patients at baseline (time of the switch) and 16 and 24 weeks thereafter. Clinical remission was defined as a Crohn's disease activity index <150 points or no fistula drainage, or a partial Mayo score <3 points for patients with UC. Serum drug trough levels and anti-drug antibodies were measured at baseline and week 16.

RESULTS

There was no significant difference in the proportion of patients in clinical remission at week 8 before the switch (82.5% with CD and 82.9% with UC), at baseline (80.6% with CD and 81.6% with UC), at week 16 (77.5% with CD and 83.7% with UC), or at week 24 (CD 76.3% with CD and 84.9% with UC) (P = .60 among groups for patients with CD and P = .98 among groups for patients with UC). For all patients, mean serum trough levels of infliximab were 5.33 ± 4.70 μg/mL at baseline and 5.69 ± 4.94 μg/mL at week 16 (P = .71); we did not find significant differences in prevalence of anti-drug antibody at baseline (16.2%) compared with week 16 (16.9%) (P = .87). Four infusion reactions occurred, until week 24 of follow up. There was no difference in outcomes or trough or antidrug antibody levels between patients with or without previous exposure to Remicade.

CONCLUSIONS

We collected data from a real-life cohort of patients with CD or UC who were switched from maintenance therapy with a biosimilar to Remicade or were treated with only Remicade. No significant changes were observed in remission, trough levels, or antidrug antibodies in patients switched from the biosimilar to Remicade. No new safety signals were detected.

The performance of Remicade®-optimized quantification assays in the assessment of Flixabi® levels

BACKGROUND

The advent of Remicade® biosimilars, Remsima®, Inflectra® and, more recently, Flixabi®, has brought along the potential to decrease the costs associated with this therapy, therefore increasing its access to a larger group of patients. However, and in order to assure a soft transition, one must make sure the assays and algorithms previously developed and optimized for Remicade perform equally well with its biosimilars. This study aimed to: (a) validate the utilization of Remicade-optimized therapeutic drug monitoring assays for the quantification of Flixabi; and (b) determine the existence of Remicade, Remsima and Flixabi cross-immunogenicity.

METHODS

Healthy donors' sera spiked with Remicade, Remsima and Flixabi were quantified using three different Remicade-quantification assays, and the reactivity of anti-Remicade and anti-Remsima sera to Remicade and to its biosimilars was assessed.

RESULTS

The results show that all tested Remicade-infliximab-optimized assays measure Flixabi as accurately as they measure Remicade and Remsima: the intraclass correlation coefficients between theoretical and measured concentrations varied from 0.920 to 0.990. Moreover, the interassay agreement values for the same compounds were high (intraclass correlation coefficients varied from 0.936 to 0.995). Finally, the anti-Remicade and anti-Remsima sera reacted to the different drugs in a similar fashion.

CONCLUSIONS

The tested assays can be used to monitor Flixabi levels. Moreover, Remicade, Remsima and Flixabi were shown to have a high cross-immunogenicity, which supports their high similarity but prevents their switching in nonresponders with antidrug antibodies.

Emerging Biotechnology Applications of Aqueous Two-Phase Systems

Liquid-liquid phase separation between aqueous solutions containing two incompatible polymers, a polymer and a salt, or a polymer and a surfactant, has been exploited for a wide variety of biotechnology applications throughout the years. While many applications for aqueous two-phase systems fall within the realm of separation science, the ability to partition many different materials within these systems, coupled with recent advances in materials science and liquid handling, has allowed bioengineers to imagine new applications. This progress report provides an overview of the history and key properties of aqueous two-phase systems to lend context to how these materials have progressed to modern applications such as cellular micropatterning and bioprinting, high-throughput 3D tissue assembly, microscale biomolecular assay development, facilitation of cell separation and microcapsule production using microfluidic devices, and synthetic biology. Future directions and present limitations and design considerations of this adaptable and promising toolkit for biomolecule and cellular manipulation are further evaluated.

A retrospective examination of the US Food and Drug Administration's clinical pharmacology reviews of oncology biologics for potential use of therapeutic drug monitoring

Background

Biologics have gained traction for use in oncology, but have demonstrate clinical variability for efficacy and safety. Therapeutic drug monitoring (TDM) can benefit patients’ outcomes from a biologic therapy when the latter has a defined therapeutic window. A clinically relevant therapeutic window may exist for biologics with established exposure-response (E–R) relationships for efficacy and/or safety and a documented maximum tolerated dose (MTD). Additionally, the inter-individual variability (IIV) on the clearance (CL) parameter could determine risks for patients falling outside the proposed therapeutic window.

Materials and methods

The US Food and Drug Administration (FDA)-approved oncology biologics between 2005–2016 were reviewed via FDA “Purple Book” (FDA-repository for licensed biologics). Data were extracted from biologics’ pharmacokinetic models available on the clinical pharmacology reviews published on the FDA-Approved Drug Products website. Evaluated features for biologics with established E–R relationships for efficacy and/or safety and MTD include an IIV for the CL and various other covariates including demographic factors, disease factors, blood chemistry, or immunogenicity.

Results

Five therapies were identified with documented E–R relationships for both efficacy and safety including, Yervoy^®(ipilimumab), Zaltrap^® (ziv-aflibercept), Portrazza^® (necitumumab), Adcetris^® (brentuximab-vedotin), and Blincyto^® (blinatumomab). The corresponding IIV on CL were: 34%, 33%, 29%, 47%, and 97%, respectively. Among the five therapies, only three had defined MTD including, brentuximab-vedotin, necitumumab, and blinatumomab.

Conclusion

Of the medications examined, blinatumomab was identified as the anticancer drug with the most available information for the establishment of TDM, and hence, may benefit through the use of TDM to optimize effectiveness and minimize patients’ toxicity. The approach used here may provide a generalizable framework to retrospectively identify anticancer biologics with high IIV that may benefit from TDM to improve patients’ clinical outcome.

Review article: consensus statements on therapeutic drug monitoring of anti-tumour necrosis factor therapy in inflammatory bowel diseases

BACKGROUND

Therapeutic drug monitoring (TDM) in inflammatory bowel disease (IBD) patients receiving anti-tumour necrosis factor (TNF) agents can help optimise outcomes. Consensus statements based on current evidence will help the development of treatment guidelines.

AIM

To develop evidence-based consensus statements for TDM-guided anti-TNF therapy in IBD.

METHODS

A committee of 25 Australian and international experts was assembled. The initial draft statements were produced following a systematic literature search. A modified Delphi technique was used with 3 iterations. Statements were modified according to anonymous voting and feedback at each iteration. Statements with 80% agreement without or with minor reservation were accepted.

RESULTS

22/24 statements met criteria for consensus. For anti-TNF agents, TDM should be performed upon treatment failure, following successful induction, when contemplating a drug holiday and periodically in clinical remission only when results would change management. To achieve clinical remission in luminal IBD, infliximab and adalimumab trough concentrations in the range of 3-8 and 5-12 μg/mL, respectively, were deemed appropriate. The range may differ for different disease phenotypes or treatment endpoints-such as fistulising disease or to achieve mucosal healing. In treatment failure, TDM may identify mechanisms to guide subsequent decision-making. In stable clinical response, TDM-guided dosing may avoid future relapse. Data indicate drug-tolerant anti-drug antibody assays do not offer an advantage over drug-sensitive assays. Further data are required prior to recommending TDM for non-anti-TNF biological agents.

CONCLUSION

Consensus statements support the role of TDM in optimising anti-TNF agents to treat IBD, especially in situations of treatment failure.

Assays for measurement of TNF antagonists in practice

Tumour necrosis factor (TNF) antagonist drug exposure is correlated with clinical, endoscopic and pathophysiological outcomes during induction and maintenance therapy. Measuring drug concentrations is therefore a useful tool when treating to target and optimising therapy. One of the main factors leading to suboptimal drug exposure is the formation of antidrug antibodies (ADAs), due to an immunogenic reaction of the immune system towards the non-self protein. The development of ADA does pose important concerns for drug efficacy and for safety as ADAs have been associated with acute infusion reactions, hypersensitivity reactions and serum sickness. Various assays exist to measure serum drug and ADA concentrations, either offered as a service in a specialised laboratory or commercially available as a kit. It is unclear how the performance of these assays relates to each other, until recently various comparative studies were carried out. The majority of these studies show that indeed a good correlation exists between the assays that measure drug, but that absolute concentrations can differ across tests. This is particularly relevant in clinical practice when a specific threshold or drug concentration range is targeted. For ADA assays, drug sensitivity or the ability of the assay to measure ADA in the presence of drug remains an important issue, especially for drugs with a higher dosing frequency. In addition, standardisation across ADA assays is difficult, making it hard to compare quantitative or semiquantitative (low/medium/high) results across assays and across studies.

The Evolving Evidence for Therapeutic Drug Monitoring of Monoclonal Antibodies in Inflammatory Bowel Disease

PURPOSE OF REVIEW

Biological medications are effective in inflammatory bowel disease (IBD) but adverse events, cost, and loss of response make their use challenging. Therapeutic drug monitoring (TDM) allows clinicians to more safely, effectively, and efficiently use medications. The purpose of this article is to review and summarize the most recent literature pertaining to TDM in IBD.

RECENT FINDINGS

Measurement of biological drug trough levels predicts ongoing patient response and can be used to titrate the medication to be more effective and efficient. Antibodies against the medications predict loss of response and adverse events. Using both parameters can predict response to subsequent biologicals. Newer biologicals show similar characteristics to those more commonly used. Management protocols using drug and antibody levels optimize medication use and may be cost-effective. Recent evidence suggests benefit to TDM of biologicals in IBD.

Therapeutic drug monitoring of CT-P13: a comparison of four different immunoassays

BACKGROUND

The commercialization of CT-P13, an infliximab (IFX) biosimilar, has the potential to decrease health-related costs and enhance access to biological therapies. This study aimed to address the accuracy and inter-assay agreement of the CT-P13 quantification using four different assays initially developed to assess IFX.

METHODS

The four different methods, one in-house method and three commercially available kits, were used to quantify exogenously-spiked samples and the sera from 185 inflammatory bowel disease (IBD) patients on CT-P13 therapy.

RESULTS

The quantification of the spiked samples unveiled a consistent and accurate behaviour of three of the tested methods, with average percentage recoveries of 90%, 102% and 109%. Results from the clinical samples demonstrated that these three assays were also highly correlated, both concerning Spearman's rank coefficients (range 0.890-0.947) and intraclass correlation coefficients (range 0.907-0.935). There were a few systematic deviations among them, but their impact in the clinical stratification of the patients using different cut-offs was minimal, particularly when these cut-offs were in the 3-4 µg/ml range, for which the strength of agreement (as assessed by the Kappa statistics that ranged from 0.732 to 0.902) was substantial to almost perfect.

CONCLUSIONS

Our results indicate that three of the tested IFX quantification methods can be used to accurately quantify CT-P13 without any adjustments.

Update on Therapeutic Drug Monitoring in Crohn's Disease

In patients with Crohn's disease on biologic medications, the use of therapeutic drug monitoring leads to a personalized approach to optimize treatment. Using an algorithmic approach, measurement of drug concentrations and anti-drug antibodies can be used to improve treatment outcomes. Therapeutic drug concentrations and absence of antibodies are associated with improved clinical and endoscopic outcomes. In clinical practice, therapeutic drug monitoring has been shown to be clinically useful and cost-effective in patients experiencing a loss of response to treatment. This review highlights the available data on therapeutic drug monitoring in the treatment of patients with Crohn's disease on biologic medications.

Biosimilars: Practical Considerations for Pharmacists

Objective: To review the scientific and regulatory aspects of biosimilar development and practical considerations for the use of biosimilars that are relevant to pharmacists. Data Sources: Literature searches of PubMed and congress abstracts for publications pertaining to biosimilars were conducted from January 2016 to January 2017. Individual drug company web pages and governmental, regulatory, and other agency websites were also reviewed. Study Selection/Data Extraction: Published articles, regulatory guidelines, and other sources covering biologic/biosimilar development and approval, reporting results of biosimilar studies or survey research, and/or identifying biosimilars in development or approved for use in Europe or the United States were reviewed and included. Data Synthesis: Biologic therapies have revolutionized the treatment of serious diseases, including hematological or autoimmune disorders and cancers. A biosimilar is highly similar to a licensed biologic (ie, reference or originator) and has no clinically meaningful differences in safety, purity, and potency. Unlike small-molecule drugs, biologics are large, complex proteins that cannot be exactly replicated, so the concept of a generic equivalent cannot be applied to biologics. Regulatory agencies have provided a framework for biosimilar approval, but there are many practical considerations for pharmacists, including interchangeability, substitution, naming, indication extrapolation, product labeling, therapeutic drug monitoring, manufacturer attributes, logistics of product use, and reimbursement. Conclusions: Pharmacists will play a key role in managing the introduction of biosimilars into health care systems. Understanding the principles of biosimilar development and evolving regulatory guidelines relevant to their use will allow pharmacists to make informed decisions regarding formulary inclusion and educate patients and other health care providers about biosimilars.

Extrapolation and Interchangeability of Infliximab and Adalimumab in Inflammatory Bowel Disease

OPINION STATEMENT

Infliximab and adalimumab biosimilars have been approved by the FDA and European Medicines Agency and have already been introduced to the international market. Availability into the US market is imminent. Biosimilars are highly similar to the reference biologic product but should not be referred to as, nor equated with, generic medications as no two biosimilars can ever be identical. Regulatory pathways for biosimilar approval consider the totality of evidence for biosimilar approvals, but the preponderance of development relies on analytic and functional testing and allows extrapolation between indications to reduce the financial burden of completing comparative clinical trials for each indication. Neither CT-P13 (infliximab biosimilar) nor ABP 501 (adalimumab biosimilar) was clinically tested in patients with inflammatory bowel disease prior to being submitted for approval by regulatory agencies. The body of available evidence suggests that these drugs will perform similarly to their originators. The pathway for interchangeability of biosimilars has yet to be clarified by federal regulators and currently remains determined by states within the USA. However, preliminary data suggests that switching from originator to biosimilar is safe with minimal differences in clinical efficacy.

Clinical impact of immunomonitoring in the treatment of inflammatory bowel disease

Despite improvement in outcomes, loss of response (LOR) to tumor necrosis factor-alpha (TNFα) therapies is a big concern in the management of inflammatory bowel disease. LOR is associated with flares of disease, increased hospitalisation rates, need for surgical interventions, and decline in quality of life. LOR may be multifactorial, but immunogenicity makes a significant contribution. Traditionally doses of anti-TNFα have been adjusted based on clinical response, using a standard approach. Immunomonitoring involves the measurement of anti-TNFα trough and antibody levels. It takes into account the underlying pharmacokinetics of anti-TNFα therapies. Expanding on this a treat to target approach may be used, where doses are intensified, or tailored to the individual based on the measurement of anti-TNFα trough and antibody levels. This review looks at the history, evolution, and clinical impact that immunomonitoring is having in the treatment of inflammatory bowel disease. It will focus on the role of immunomonitoring in helping to achieve long lasting deep remission and mucosal healing. It will explore the different options in terms of best measuring trough and antibody levels, explore possible advantages of immunomonitoring, and discuss its role in best optimising response, at induction, during the maintenance phase of treatment, as well as a role in withdrawing or switching therapy.

Therapeutic drug monitoring of anti-tumour necrosis factor-α agents in inflammatory bowel disease

INTRODUCTION

Anti-TNFα therapy has revolutionised treatment of inflammatory bowel disease, however primary non-response and secondary loss of response are a significant problem. Therapeutic drug monitoring (TDM) has recently emerged as a means of optimising use of anti-TNFα agents. Areas covered: TDM of anti-TNFα agents can guide clinical decisions during treatment failure events, prevent treatment failure events, and potentially result in significant healthcare cost saving. TDM for anti-TNFα agent involves measurement of drug levels and anti-drug antibodies, and can be performed reactively or proactively. Reactive TDM reserves testing for treatment failure events, while proactive TDM also consists of periodic TDM for patients responding to anti-TNFα therapy to allow treatment optimisation. Generation of anti-drug antibodies is recognised as one important mechanism of treatment failure and adverse events. Expert opinion: Evidence strongly supports TDM at time of treatment failure, while studies employing proactive TDM have demonstrated conflicting results. TDM can also help better select patients likely to remain in clinical remission on anti-TNFα treatment interruption. Currently TDM is used to optimise anti-TNFα treatment, but it is not used by most clinicians to prevent adverse reactions to anti-TNFα agents.

Rapid Test for Infliximab Drug Concentration Allows Immediate Dose Adaptation

OBJECTIVES

Therapeutic drug monitoring of infliximab improves treatment outcomes, but available assays to monitor infliximab lack speed to implement treatment algorithms immediately. Our aim is to validate a rapid, lateral flow-based assay (LFA) for quantitative determination of infliximab and to assess thresholds associated with mucosal healing in patients with ulcerative colitis.

METHODS

Samples (n=190) from 29 anti-tumor necrosis factor naive patients with ulcerative colitis starting infliximab induction therapy between June 2010 and February 2012 were prospectively collected. All patients had a Mayo endoscopic sub-score ≥2 at baseline. Mucosal healing (MH), defined as a Mayo endoscopic sub-score ≤1, was evaluated at week 10-14. Infliximab trough concentrations (TC) were determined with a novel LFA, which was benchmarked with the RIDASCREEN infliximab Monitoring (ELISA).

RESULTS

The LFA showed an excellent agreement with enzyme-linked immunosorbent assay (ELISA) for quantification of infliximab, as observed from Pearson and intraclass correlation coefficients of 0.95 and 0.95 during induction and 0.93 and 0.87 during maintenance therapy, respectively. In total, 45% of patients achieved MH. Using the LFA, week 14 TC ≥2.1 μg/ml (AUROC: 0.819, P=0.008) were associated with MH. After 2 years follow-up, 77% of patients with MH were still receiving infliximab therapy vs. 25% of patients without MH.

CONCLUSIONS

We validated a LFA for quantification of infliximab and identified TC associated with MH. With a time-to-result of 20 min, individual sample analysis and user-friendliness, the LFA outplays ELISA as a rapid, accurate tool to monitor infliximab concentrations.

Efficacy of Infliximab Biosimilar CT-P13 Induction Therapy on Mucosal Healing in Ulcerative Colitis

INTRODUCTION

CT-P13 is the first biosimilar to infliximab that has been approved for the same indications as its originator infliximab. No data are available on the effect of infliximab biosimilar on mucosal healing. The aim of this study was to evaluate the efficacy of CT-P13 induction therapy on mucosal healing in patients with ulcerative colitis [UC].

PATIENTS AND METHODS

UC patients, who received CT-P13 therapy from its local introduction at three Hungarian and one Czech inflammatory bowel disease centres, were prospectively enrolled. Sigmoidoscopy was performed after the end of the induction therapy at week 14. Mucosal healing was defined as Mayo endoscopic subscore 0 or 1. Complete mucosal healing was defined as Mayo endoscopic subscore 0. Trough level of CT-P13 was measured at week 14.

RESULTS

Sixty-three UC patients who underwent CT-P13 induction therapy were enrolled in the study. Indication for the therapy was acute, severe flare up and chronic, refractory activity in 24 and 39 patients, respectively. Cumulative clinical response and steroid-free remission at week 14 were achieved in 82.5% and 47.6% of the patients, respectively. Sigmoidoscopy revealed steroid-free mucosal healing in 47.6% of the patients, and complete mucosal healing was present in 27%. Mayo endoscopic subscore decreased significantly at week 14 compared to baseline. Trough levels of infliximab correlated with mucosal healing.

CONCLUSION

This is, to our knowledge, the first study examining the efficacy of CT-P13 induction therapy on mucosal healing in UC. The results indicate that mucosal healing is achieved in two-thirds of UC patients by the end of the induction treatment with CT-P13.

Proactive therapeutic drug monitoring of infliximab: a comparative study of a new point-of-care quantitative test with two established ELISA assays

BACKGROUND

Therapeutic drug monitoring is a powerful strategy known to improve the clinical outcomes and to optimise the healthcare resources in the treatment of autoimmune diseases. Currently, most of the methods commercially available for the quantification of infliximab (IFX) are ELISA-based, with a turnaround time of approximately 8 h, and delaying the target dosage adjustment to the following infusion.

AIM

To validate the first point-of-care IFX quantification device available in the market - the Quantum Blue Infliximab assay (Buhlmann, Schonenbuch, Switzerland) - by comparing it with two well-established methods.

METHODS

The three methods were used to assay the IFX concentration of spiked samples and of the serum of 299 inflammatory bowel diseases (IBD) patients undergoing IFX therapy.

RESULTS

The point-of-care assay had an average IFX recovery of 92%, being the most precise among the tested methods. The Intraclass Correlation Coefficients of the point-of-care IFX assay vs. the two ELISA-based established methods were 0.889 and 0.939. Moreover, the accuracy of the point-of-care IFX compared with each of the two reference methods was 77% and 83%, and the kappa statistics revealed a substantial agreement (0.648 and 0.738).

CONCLUSIONS

The Quantum Blue IFX assay can successfully replace the commonly used ELISA-based IFX quantification kits. This point-of-care IFX assay is able to deliver the results within 15 min makes it ideal for an immediate target concentration adjusted dosing. Moreover, it is a user-friendly desktop device that does not require specific laboratory facilities or highly specialised personnel.

Advances in Therapeutic Drug Monitoring of Biologic Therapies in Inflammatory Bowel Disease: 2015 in Review

OPINION STATEMENT

Monoclonal antibody therapy directed against tumor necrosis factor-alpha (anti-TNFs) has revolutionized the care of patients with Crohn's disease and ulcerative colitis. These large proteins are potentially immunogenic. Early clinical trials demonstrated an association with both serum concentrations of these agents as well as the presence of antidrug antibodies generated by the host with loss of response. More recent research has provided further evidence to confirm the impact of low drug trough concentrations and antidrug antibodies on subsequent clinical course in CD and UC. Given these clinical implications, treatment algorithms have been developed to aid clinicians in interpreting trough drug levels and antibody concentrations in those with confirmed active disease. Several studies have demonstrated the utility of these approaches. Furthermore, there are growing data supporting the use of therapeutic drug monitoring in a prospective fashion in those patients who are clinically stable on anti-TNF therapies to ensure they are receiving appropriate dosing and have not yet developed antibodies. In addition, for those who have developed low-level antibodies, increasing the dose of an anti-TNF or adding an immunomodulator may help to overcome this immunologic response. Further research is required to assess these proposed strategies, as well as to determine the role of trough drug level assessment and antibody testing for new anti-TNFs and biologic medication with alternative mechanisms of action.