A value proposition for trough level-based anti-TNFα drug dosing.

Treatment of inflammatory bowel diseases and rheumatic disorders with anti-tumor necrosis factor alpha (TNFα) drugs is expensive, while a significant proportion of patients does not show adequate clinical response. Therapeutic drug monitoring (TDM) enables patient-specific anti-TNFα therapy. The role of laboratory tests in clinical care has recently been described in a value proposition framework. It describes care processes, stakeholders, costs, risks, benefits and patient outcomes based on the use of a laboratory test in a clinical care pathway. We have applied this concept to the use of TDM for anti-TNFα drugs, describing evidence that supports the intervention and its cost effectiveness, steps that need to be adjusted in the care pathway, possible treatment algorithms and measures to assess adoption of this framework into clinical practice. For effective TDM, an assay for measurement of drug levels together with appropriate target ranges and an anti-drug-antibody assay have to be implemented. Also, instead of only reporting the drug concentration, laboratorians, pharmacists and clinicians should deliver added value by introducing a TDM-based treatment algorithm into clinical practice. Thus, to maximize effectiveness of TDM of anti-TNFα therapy in routine care, adjustment of current care pathways and cooperation of many stakeholders are needed.

Switching from infliximab innovator to biosimilar in patients with inflammatory bowel disease: a 12-month multicentre observational prospective cohort study.

BACKGROUND: Infliximab biosimilars have become available for treatment of inflammatory bowel disease (IBD). However, data showing long-term safety and effectiveness of biosimilars in IBD patients are limited. AIM: To study prospectively the switch from infliximab innovator to biosimilar in an IBD cohort with 12 months follow-up to evaluate safety and effectiveness. METHODS: Adult IBD patients from two hospitals treated with infliximab innovator (Remicade; Janssen Biotech,  Horsham ,  Pennsylvania, USA) were switched to infliximab biosimilar (Inflectra; Hospira, Lake Forest, Illinois, USA) as part of routine care, but in a controlled setting. Blood samples were taken just before the first, second, fourth and seventh infusion of biosimilar. Infliximab trough levels, antibodies-to-infliximab (ATI), CRP and ESR were measured and disease activity scores were calculated. RESULTS: Our cohort consisted of 133 IBD patients (64% CD, 36% UC). Before switching we found widely varying infliximab levels (median 3.5 µg/mL). ATI were detected in eight patients (6%). Most patients were in remission or had mild disease (CD: 82% UC: 90%). After switching to biosimilar, 35 patients (26%) discontinued therapy within 12 months, mostly due to subjective higher disease activity (9%) and adverse events (AE, 9.8%). AE included general malaise/fatigue (n = 7), arthralgia (n = 2), skin problems (n = 2) and infusion reactions (n = 2). No differences in IFX levels, CRP, and disease activity scores were found between the four time points (P ≥ .0917). CONCLUSIONS: We found no differences in drug levels and disease activity between infliximab innovator and biosimilar in our IBD cohort, indicating that biosimilars are safe and effective. The high proportions of discontinuers were mostly due to elective withdrawal or subjective disease worsening.

Therapeutic drug monitoring (TDM) as a tool in the switch from infliximab innovator to biosimilar in rheumatic patients: results of a 12-month observational prospective cohort study.

The objective of this study is to apply therapeutic drug monitoring (TDM) as an objective tool to monitor the switch from infliximab innovator (INX) to infliximab biosimilar (INB) in our diverse rheumatic cohort in daily clinical practice. All rheumatic patients on INX treatment (Remicade®) and ≥18 years were switched to INB (Inflectra®) as part of routine care, but in a controlled setting. Patients were monitored by taking blood samples just before the first infusion of INB (T1), and after the second (T2), fourth (T3), and seventh (T4) infusion of INB. T4 reflects the patients' status after ∼12 months. Infliximab trough levels, antibodies-to-infliximab (ATI), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and validated disease activity scores (if possible) were measured. Our population consisted of 27 patients with seven different rheumatic diseases who had received INX for 143 (58-161) months (median (IQR)). Half of the patients (52%) received concomitant immunosuppressives. We found widely varying infliximab levels, with only 56% within the proposed therapeutic range of 1-5 µg/mL. One patient had very high ATI levels (>880 au/mL), and two had low ATI levels (≤30 au/mL). After switching to INB, seven patients (26%) discontinued the therapy, partially due to subjective reasons. No difference in infliximab levels, CRP levels, and disease activity scores was found between the four time points (p ≥ 0.2460). In conclusion, no pharmacokinetic or clinical differences were found between INX and INB in our diverse rheumatic cohort. TDM is a helpful tool to monitor patients switching from INX to INB.

Determination of dabigatran and rivaroxaban by ultra-performance liquid chromatography-tandem mass spectrometry and coagulation assays after major orthopaedic surgery.

Major orthopaedic surgery is associated with an increased risk of venous thromboembolism. Direct oral anticoagulants (DOACs) are recommended as thromboprophylactic agents after orthopaedic surgery. Although routine monitoring of DOACs in general is not required, measuring DOAC concentration may be necessary in clinical settings. The effects of DOACs on routine coagulation assays in spiked material are studied extensively, however, few data are available on DOAC concentration in patients after major orthopaedic surgery. We measured trough and peak DOAC concentrations with UPLC-MS/MS and routine coagulation tests in a prospective study including 40 patients receiving thromboprophylactic treatment with dabigatran 220mg od and 40 patients receiving rivaroxaban 10mg od after major orthopaedic surgery. For rivaroxaban, the median trough concentration with UPLC-MS/MS was 17.1ng/mL and median peak concentration was 149ng/mL. The anti-Xa assay displayed a good correlation, but a positive bias in comparison to the reference method. Furthermore, trough levels were mostly below the LOD of the anti-Xa assay. For dabigatran, the median trough concentration with UPLC-MS/MS was 12.1ng/mL, and median peak level was 80.8ng/mL. A positive bias was found when results from coagulation assays were compared to UPLC-MS/MS data. However, the addition of glucuronidated metabolites to dabigatran concentration UPLC-MS/MS data generally resolved most of this bias. Age was found to have a significant influence on dabigatran pharmacokinetics, irrespective of kidney function, whereas no effect of age was found during rivaroxaban treatment. In both treatment groups, female subjects displayed faster pharmacokinetics in comparison to male subjects, although not reaching significance. We conclude that UPLC-MS/MS is the method of choice to measure trough concentrations of DOACs in patients after orthopaedic surgery. Current coagulation assays are not suited for this purpose. We found large heterogeneity in both peak and trough concentrations of DOACs, and showed that pharmacokinetics of novel oral anticoagulants may be influenced by age and gender. Whether patients with high or low trough concentrations are at increased risk for bleeding or thromboembolic events respectively remains to be established.

Determination of dabigatran, rivaroxaban and apixaban by ultra-performance liquid chromatography - tandem mass spectrometry (UPLC-MS/MS) and coagulation assays for therapy monitoring of novel direct oral anticoagulants.

BACKGROUND: Three novel direct oral anticoagulants (DOACs) have recently been registered by the Food and Drug Administration and European Medicines Agency Commission: dabigatran, rivaroxaban, and apixaban. To quantify DOACs in plasma, various dedicated coagulation assays have been developed. OBJECTIVE: To develop and validate a reference ultra-performance liquid chromatography - tandem mass spectrometry (UPLC-MS/MS) method and to evaluate the analytical performance of several coagulation assays for quantification of dabigatran, rivaroxaban, and apixaban. METHODS: The developed UPLC-MS/MS method was validated by determination of precision, accuracy, specificity, matrix effects, lower limits of detection, carry-over, recovery, stability, and robustness. The following coagulation assays were evaluated for accuracy and precision: laboratory-developed (LD) diluted thrombin time (dTT), Hemoclot dTT, Pefakit PiCT, ECA, Liquid anti-Xa, Biophen Heparin (LRT), and Biophen DiXal anti-Xa. Agreement between the various coagulation assays and UPLC-MS/MS was determined with random samples from patients using dabigatran or rivaroxaban. RESULTS: The UPLC-MS/MS method was shown to be accurate, precise, sensitive, stable, and robust. The dabigatran coagulation assay showing the best precision, accuracy and agreement with the UPLC-MS/MS method was the LD dTT test. For rivaroxaban, the anti-factor Xa assays were superior to the PiCT-Xa assay with regard to precision, accuracy, and agreement with the reference method. For apixaban, the Liquid anti-Xa assay was superior to the PiCT-Xa assay. CONCLUSIONS: Statistically significant differences were observed between the various coagulation assays as compared with the UPLC-MS/MS reference method. It is currently unknown whether these differences are clinically relevant. When DOACs are quantified with coagulation assays, comparison with a reference method as part of proficiency testing is therefore pivotal.