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

Comparative study of a point-of-care test and an enzyme-linked immunosorbent assay (ELISA) for infliximab levels

BACKGROUND

Proactive therapeutic drug monitoring (TDM) is often challenged by long turnaround time when using enzyme-linked immunosorbent assays (ELISAs), especially when analyses are centralised. Point-of-care tests (POCTs) allow rapid assessments, but data on their agreement with existing in-house methodologies are scarce.

OBJECTIVE

To examine the agreement between a POCT by ProciseDx (San Diego, CA) and the most frequently used in-house ELISA for infliximab (IFX) quantification in Sweden.

METHODS

Serum samples were analysed using the in-house ELISA, Karolinska University Hospital, Stockholm, Sweden and a POCT by ProciseDx (San Diego, CA). Agreement was assessed and differences were examined.

RESULTS

Samples from 61 inflammatory bowel disease (IBD) patients were analysed with a median IFX concentration of 7.9 μg/mL (interquartile range (IQR) 5.5-13) for the POCT and 7.9 μg/mL (IQR 5.2-12) for the ELISA (Pearson's correlation coefficient = 0.95 (95% CI 0.92-0.97, p < .01)). A Passing-Bablok regression yielded an intercept of -0.44 and a slope of 1.09. The Bland-Altman plot showed a systemic bias of -0.77 μg/mL (95% CI -0.18 to -1.4) between the methods. The upper limit of agreement was 3.7 (95% CI 2.7-4.8) (μg/mL), whereas the lower limit agreement was -5.3 (95% CI -6.3 to -4.3) (μg/mL). An excellent reliability was observed, intraclass correlation showed = 0.94 (95% CI 0.89-0.96, p < .0001). When defining IFX concentration as subtherapeutic (<3.0 μg/mL), therapeutic (3.0-7.0 μg/mL) or supratherapeutic (>7.0 μg/mL) drug levels, Kappa statistics showed a substantial agreement (0.79).

CONCLUSIONS

The POCT by ProciseDx (San Diego, CA) demonstrated a good agreement with the in-house ELISA, supporting its use for rapid IFX quantification.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LC–MS3 Strategy for Quantification of Carbamazepine in Human Plasma and Its Application in Therapeutic Drug Monitoring

This study developed a detection method based on the strategy of HPLC/MS³ and verified its suitability by quantifying carbamazepine in human plasma. The high-performance liquid chromatography–tandem mass spectrometry (HPLC/MS³) system was performed using a Shimadzu UFLC XR liquid chromatography and a SCIEX QTRAP^® 5500 linear ion trap triple quadrupole mass spectrometer. The specific operation was as follows: the sample protein was firstly precipitated using methanol, then carbamazepine and carbamazepine-D₂N¹⁵ were separated on an ACQUITY UPLC HSS T3 column using the gradient elution with solvent A (0.1% formic acid) and solvent B (0.1% formic acid in acetonitrile) at a flow rate of 0.25 mL/min. Each sample was run for 7 min. This method was validated for various parameters including accuracy, precision, selectivity, linearity, LLOQ, etc. Only 5 μL of sample plasma could obtain the result of LLOD 0.5 µg/mL. The intra-day and inter-day precision was <8.23%, and accuracy was between −1.74% and 2.92%. This method was successfully used for monitoring the blood concentration of epilepsy patients after carbamazepine treatment.

Accurate and rapid microfluidic ELISA to monitor Infliximab titers in patients with inflammatory bowel diseases

Inflammatory bowel disease (IBD) is a term used to describe disorders that involve chronic inflammation in the gastrointestinal tract, affecting more than 6.8 million people worldwide. Biological therapy is used in the most severe cases of IBD where anti-tumour necrosis factor-alpha (TNF-α) antibodies are the first choice for a biological treatment. When administrated to patients, these antibodies interact with TNF-α, usually overexpressed in these diseases, neutralizing its biological activity. Because of the chronic nature of these diseases, a recurring administration of the therapeutic antibodies is required, thus making therapy monitorization essential for the correct management of these diseases. The aim of this work is the development of an enzyme-linked immunosorbent assay (ELISA) microfluidic biosensor to quantify the therapeutic antibodies in IBD patient plasma samples, where the commercial monoclonal antibody Infliximab (IFX) is used as a model target. By providing a faster and more accurate measurement of IFX, the proposed method leads to improved therapy scheduling and a reduced risk of endogenous anti-drug antibodies (ADAs) reducing the efficacy of the treatment. The time needed between sample insertion and result output for the microfluidic ELISA (mELISA) is 24 minutes, drastically shorter than the time required by the conventional ELISA (cELISA). The mELISA presented in this work has a LoD of 0.026 μg mL^-1, while commercially available solutions provide a LoD of 0.15 μg mL^-1. Results acquired by the mELISA are highly correlated with the results obtained from the cELISA (r = 0.998; R² = 0.996; p < 0.0001), demonstrating the validity of the microfluidic approach for the quantification of IFX from patient plasma and its potential for use at the point-of-care (POC).

Quantitation of Trastuzumab and an Antibody to SARS-CoV-2 in Minutes Using Affinity Membranes in 96-Well Plates

Quantitation of therapeutic monoclonal antibodies (mAbs) in human serum could ensure that patients have adequate levels of mAbs for effective treatment. This research describes the use of affinity, glass-fiber membranes in a 96-well-plate format for rapid (<5 min) quantitation of the therapeutic mAb trastuzumab and a mAb against the SARS-CoV-2 spike protein. Adsorption of a poly(acrylic acid)-containing film in membrane pores and activation of the -COOH groups in the film enable covalent-linking of affinity peptides or proteins to the membrane. Passage of mAb-containing serum through the affinity membrane results in mAb capture within 1 min. Subsequent rinsing, binding of a secondary antibody conjugated to a fluorophore, and a second rinse yield mAb-concentration-dependent fluorescence intensities in the wells. Calibration curves established from analyses on different days have low variability and allow determination of mAb levels in separately prepared samples with an average error <10%, although errors in single-replicate measurements may reach 40%. The assays can occur in diluted serum with physiologically relevant mAb concentrations, as well as in undiluted serum. Thus, the combination of 96-well plates containing affinity membranes, a microplate reader, and a simple vacuum manifold affords convenient mAb quantitation in <5 min.

A Comprehensive Literature Review and Expert Consensus Statement on Therapeutic Drug Monitoring of Biologics in Inflammatory Bowel Disease

Therapeutic drug monitoring (TDM) of biologics is a rapidly evolving field. We aimed to provide a consensus statement regarding the clinical utility of TDM for biologics in inflammatory bowel disease (IBD). A modified Delphi method was applied to develop consensus statements. A comprehensive literature review was performed regarding TDM of biologic therapies in IBD, and 45 statements were subsequently formulated on the potential application of TDM in IBD. The statements, along with literature, were then presented to a panel of 10 gastroenterologists with expertise in IBD and TDM who anonymously rated them on a scale of 1-10 (1 = strongly disagree and 10 = strongly agree). An expert consensus development meeting was held virtually to review, discuss, refine, and reformulate statements that did not meet criteria for agreement or that were ambiguous. During the meeting, additional statements were proposed. Panelists then confidentially revoted, and statements rated ≥7 by 80% or more of the participants were accepted. During the virtual meeting, 8 statements were reworded, 7 new statements were proposed, and 19 statements were rerated. Consensus was finally reached in 48/49 statements. The panel agreed that reactive TDM should be used for all biologics for both primary nonresponse and secondary loss of response. It was recommended that treatment discontinuation should not be considered for infliximab or adalimumab until a drug concentration of at least 10-15 μg/mL was achieved. Consensus was also achieved regarding the utility of proactive TDM for anti-tumor necrosis factor therapy. It was recommended to perform proactive TDM after induction and at least once during maintenance. Consensus was achieved in most cases regarding the utility of TDM of biologics in IBD, specifically for reactive and proactive TDM of anti-tumor necrosis factors.

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.

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.

Anti-TNF biosimilars in Crohn's Disease: a patient-centric interdisciplinary approach

Introduction: The purpose of this review is to highlight the role of biosimilars in early treatment in IBD and introduce ways to facilitate a patient-centric switching process through multidisciplinary approach. Areas covered: We summarize existing scientific literature related to the role of biosimilars in inflammatory bowel disease in terms of early treatment and cost-saving and implementing switching process. Expert opinion: Use of anti-TNF biosimilars in patients has the potential for large drug-acquisition cost-saving, which can be reinvested into early treatment. Managed switched programs for adalimumab can add further benefits in the future.

Appropriate Therapeutic Drug Monitoring of Biologic Agents for Patients With Inflammatory Bowel Diseases

BACKGROUND & AIMS

Therapeutic drug monitoring (TDM) is widely available for biologic therapies in patients with inflammatory bowel disease (IBD). We reviewed current data and provided expert opinion regarding the clinical utility of TDM for biologic therapies in IBD.

METHODS

We used a modified Delphi method to establish consensus. A comprehensive literature review was performed regarding the use of TDM of biologic therapy in IBD and presented to international IBD specialists. Subsequently, 28 statements on the application of TDM in clinical practice were rated on a scale of 1 to 10 (1 = strongly disagree and 10 = strongly agree) by each of the panellists. Statements were accepted if 80% or more of the participants agreed with a score ≥7. The remaining statements were discussed and revised based on the available evidence followed by a second round of voting.

RESULTS

The panel agreed on 24 (86%) statements. For anti-tumor necrosis factor (anti-TNF) therapies, proactive TDM was found to be appropriate after induction and at least once during maintenance therapy, but this was not the case for the other biologics. Reactive TDM was appropriate for all agents both for primary non-response and secondary loss of response. The panellists also agreed on several statements regarding TDM and appropriate drug and anti-drug antibody (ADA) concentration thresholds for biologics in specific clinical scenarios.

CONCLUSION

Consensus was achieved towards the utility of TDM of biologics in IBD, particularly anti-TNF therapies. More data are needed especially on non-anti-TNF biologics to further define optimal drug concentration and ADA thresholds as these can vary depending on the therapeutic outcomes assessed.

Comparison of ELISA and HPLC-MS methods for the determination of exenatide in biological and biotechnology-based formulation matrices

The development of biotechnology-based active pharmaceutical ingredients, such as GLP-1 analogs, brought changes in type 2 diabetes treatment options. For better therapeutic efficiency, these active pharmaceutical ingredients require appropriate administration, without the development of adverse effects or toxicity. Therefore, it is required to develop several quantification methods for GLP-1 analogs products, in order to achieve the therapeutic goals, among which ELISA and HPLC arise. These methods are developed, optimized and validated in order to determine GLP-1 analogs, not only in final formulation of the active pharmaceutical ingredient, but also during preclinical and clinical trials assessment. This review highlights the role of ELISA and HPLC methods that have been used during the assessment for GLP-1 analogs, especially for exenatide.

Switching from originator infliximab to the biosimilar CT-P13 in 313 patients with inflammatory bowel disease

BACKGROUND

As the patents of originator biologics are expiring, biosimilar versions are becoming available for the treatment of inflammatory bowel disease (IBD). However, published switch studies of the first infliximab biosimilar, CT-P13, have delivered ambiguous results that could be interpreted as showing a trend towards inferior effectiveness in Crohn's disease (CD) compared with ulcerative colitis (UC). The aim of this study was to investigate the effectiveness and safety of switching IBD patients from treatment with Remicade to CT-P13.

METHODS

In this prospective observational cohort study, all adult IBD patients on Remicade treatment, at four hospitals, were switched to CT-P13. The primary endpoint was change in clinical disease activity at 2, 6, and 12 months after the switch. Secondary endpoints were subgroup analyses of patients with and without concomitant immunomodulators; changes in biomarkers, quality of life, drug trough levels and anti-drug antibodies (ADAbs); and adverse events.

RESULTS

A total of 313 IBD patients were switched (195 CD; 118 UC). There were no significant changes in clinical disease activity, quality of life, biomarkers (except a small but significant increase in albumin in CD) including F-calprotectin, drug trough levels, or proportion of patients in remission. Disease worsening rates were 14.0% for CD and 13.8% for UC; and 2.7% developed ADAbs and 2.2% developed serious adverse events.

CONCLUSIONS

This is the largest study of switched IBD patients published to date, and it demonstrates that switching from Remicade to CT-P13 may be done with preserved therapeutic effectiveness and safety in both CD and UC.

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.