Interpreting hydroxychloroquine blood levels for medication non-adherence: a pharmacokinetic study

OBJECTIVE

Characterise the relationship between hydroxychloroquine (HCQ) blood levels and the number of missed doses, accounting for dosage, dose timing and the large variability in pharmacokinetics (PK) between patients.

METHODS

We externally validated a published PK model and then conducted dosing simulations. We developed a virtual population of 1000 patients for each dosage across a range of body weights and PK variability. Using the model, 10 Monte Carlo simulations for each patient were conducted to derive predicted whole blood concentrations every hour over 24 hours (240 000 HCQ levels at steady state). To determine the impact of missed doses on levels, we randomly deleted a fixed proportion of doses.

RESULTS

For patients receiving HCQ 400 mg daily, simulated random blood levels <200 ng/mL were exceedingly uncommon in fully adherent patients (<0.1%). In comparison, with 80% of doses missed, approximately 60% of concentrations were <200 ng/mL. However, this cut-off was highly insensitive and would miss many instances of severe non-adherence. Average levels quickly dropped to <200 ng/mL after 2-4 days of missed doses. Additionally, mean levels decreased by 29.9% between peak and trough measurements.

CONCLUSIONS

We propose an algorithm to optimally interpret HCQ blood levels and approximate the number of missed doses, incorporating the impact of dosage, dose timing and pharmacokinetic variability. No single cut-off has adequate combinations of both sensitivity and specificity, and cut-offs are dependent on the degree of targeted non-adherence. Future studies should measure trough concentrations to better identify target HCQ levels for non-adherence and efficacy.

High BMI is associated with lower TNF-α inhibitor serum trough levels and higher disease activity in patients with axial spondyloarthritis

BACKGROUND

TNF-α inhibitor (TNFi) serum trough levels have previously been found to be related to disease activity in axial spondyloarthritis (axSpA). However, most research regarding serum trough levels has been conducted in patients who only recently started TNFi therapy. Therefore, our objective was to explore TNFi serum trough level measurements in relation to disease activity and BMI in the total axSpA population in daily clinical practice, also including patients on long-term TNFi therapy.

METHODS

Consecutive patients from the Groningen Leeuwarden Axial Spondyloarthritis (GLAS) cohort were approached for a TNFi serum trough level measurement during their regular outpatient visit at the UMCG. Spearman's correlation coefficient was used to analyse the relation of serum trough levels with disease activity and BMI. Logistic regression was performed to analyse the relation between therapeutic drug levels and disease activity, corrected for potential confounders, including BMI.

RESULTS

Thirty-four patients on adalimumab and 21 patients on etanercept were included. Mean age was 45 ± 12 years, 47% were male, median BMI was 26.4 (IQR 23.9-32.5) and median treatment duration was 41 months (range 2-126). According to definitions of Sanquin, 47% of patients had therapeutic serum trough levels. No significant correlations were found between TNFi levels and disease activity (ASDAS-CRP: adalimumab: ρ = -0.16, p = 0.39; etanercept: ρ = -0.29, p = 0.20). TNFi levels were moderately correlated with BMI (adalimumab: ρ = -0.48, p = 0.004; etanercept: ρ = -0.50, p = 0.021). Patients with active disease (ASDAS ≥ 2.1) showed higher BMI than patients with inactive disease (median 29.7 vs. 24.6, p = 0.015). In multivariable regression analyses, BMI was identified as the only confounder for the relationship between therapeutic drug levels and ASDAS.

CONCLUSION

In this cross-sectional, observational study of axSpA patients mainly on long-term treatment with TNFi, higher BMI was significantly associated with lower adalimumab and etanercept serum trough levels and higher disease activity.

Increased Levels of Omega-3 Fatty Acids and DHA Are Linked to Pain Reduction in Rheumatoid Arthritis Patients Treated with Janus Kinase Inhibitors

Although Janus kinase inhibitors (JAKi) could reduce patient-reported pain in rheumatoid arthritis (RA), their mechanism remains unclear. Therefore, we examined lipid metabolites change in JAKi-treated patients and evaluate their association with pain reduction. We used ¹H-NMR-based lipid/metabolomics to determine serum levels of lipid metabolites at baseline and week 24 of treatment. Serum levels of significant lipid metabolites were replicated by ELISA in 24 JAKi-treated and 12 tocilizumab-treated patients. Pain was evaluated with patients’ assessment on a 0–100 mm VAS, and disease activity assessed using DAS28. JAKi or tocilizumab therapy significantly reduced disease activity. Acceptable pain (VAS pain ≤20) at week 24 was observed in 66.7% of JAKi-treated patients, and pain decrement was greater than tocilizumab-treated patients (ΔVAS pain 70.0 vs. 52.5, p = 0.0595). Levels of omega-3 fatty acids and docosahexaenoic acid (DHA) were increased in JAKi-treated patients (median 0.55 mmol/L versus 0.71 mmol/L, p = 0.0005; 0.29 mmol/L versus 0.35 mmol/L, p = 0.0004; respectively), which were not observed in tocilizumab-treated patients. ELISA results showed increased DHA levels in JAKi-treated patients with acceptable pain (44.30 µg/mL versus 45.61 µg/mL, p = 0.028). A significant association of pain decrement with DHA change, not with DAS28 change, was seen in JAKi-treated patients. The pain reduction effect of JAKi probably links to increased levels of omega-3 fatty acids and DHA.

Development and Validation of a Simple and Rapid Ultrahigh-Performance Liquid Chromatography Tandem Spectrometry Method for the Quantification of Hydroxychloroquine in Plasma and Blood Samples in the Emergency Context of SARS-CoV-2 Pandemic

ABSTRACT

Therapeutic drug monitoring of hydroxychloroquine (HCQ) has been recommended to optimize the treatment of patients with COVID-19. The authors describe an ultrahigh-performance liquid chromatography tandem spectrometry method developed in a context of emergency, to analyze HCQ in both human plasma and blood samples. After adding the labeled internal standard and simple protein precipitation, plasma samples were analyzed using a C18 column. Blood samples required evaporation before analysis. The total chromatographic run time was 4 minutes (including 1.5 minutes of column equilibration). The assay was linear over the calibration range (r2 > 0.99) and up to 1.50 mcg/mL for the plasma samples (5.00 mcg/mL for the blood matrix). The limit of quantification was 0.0150 mcg/mL for plasma samples (0.05 mcg/mL blood matrix) with accuracy and precision ranging from 91.1% to 112% and from 0.750% to 11.1%, respectively. Intraday and interday precision and accuracy values were within 15.0%. No significant matrix effect was observed in the plasma or blood samples. This method was successfully applied to patients treated for COVID-19 infection. A simple and rapid ultrahigh-performance liquid chromatography tandem spectrometry method adapted to HCQ therapeutic drug monitoring in the context of SARS-CoV-2 infection was successfully developed and validated.

The influence of obesity on hydroxychloroquine blood levels in lupus nephritis patients

INTRODUCTION

In 2016 the American Academy of Ophthalmology(2016-AAO) recommended a maximum daily HCQ use of 5.0 mg/kg real body weight(RBW) taking into consideration minimizing eye toxicity. Retinopathy in systemic lupus erythematosus(SLE) patients was recently associated with obesity and this condition is progressively more common in these patients. However, the impact of obesity in HCQ blood levels remains controversial.

OBJECTIVE

To determine if the 2016-AAO recommendation based on RBW with and without maximum daily dose restriction results in adequate and safe blood levels in obese lupus nephritis(LN) patients.

METHODS

A cross-sectional study was performed with 108 LN patients under the prescribed 2016-AAO dose for at least 3 months. LN patients were assessed for demographic characteristics, body mass index(BMI), disease parameters, HCQ dose, concomitant treatment and HCQ blood levels measured by liquid chromatography-tandem mass spectrometry. Obesity was defined as BMI ≥30kg/m².

RESULTS

Obesity was identified in 35/108(32%) LN patients. The calculation of HCQ daily dosage revealed that obese patients were under a lower prescribed daily dose according to the real body weight (RBW) [4.4(2.9-5.4) vs. 4.9(4-5.5)mg/Kg/day, p < 0.001] due to the maximum limit used. Regardless of that the median of HCQ blood levels was significantly higher in obese compared to non-obese patients (1562 ± 548.6 vs. 1208 ± 448.9 ng/mL, p = 0.002). Further analysis of patients under the 20016-AAO recommendation by RBW without the restriction of maximum daily dose confirmed that in spite of comparable daily dose in 14 obese patients and 61 non-obese patients [4.8 (4.5-5.4) vs. 5.0(4.5-5.5) mg/kg, p = 0.312], the median of HCQ blood levels was significantly higher in obese patients than in non-obese (1734 ± 457.3 vs. 1189 ± 449.4 ng/mL, p < 0.001).

CONCLUSION

Obese patients under the 2016-AAO prescribed dose of HCQ based on RBW with and without maximum daily dose restriction have a very high HCQ blood levels compared to non-obese patients, with a potential increased risk of ocular toxicity. The use of 2016-AAO dose of HCQ according to the ideal body weight for this group of patients should be considered.Clinicaltrials.gov #NCT0312243.

Blood pro-resolving mediators are linked with synovial pathology and are predictive of DMARD responsiveness in rheumatoid arthritis

Biomarkers are needed for predicting the effectiveness of disease modifying antirheumatic drugs (DMARDs). Here, using functional lipid mediator profiling and deeply phenotyped patients with early rheumatoid arthritis (RA), we observe that peripheral blood  specialized pro-resolving mediator (SPM) concentrations are linked with both DMARD responsiveness and disease pathotype. Machine learning analysis demonstrates that baseline plasma concentrations of resolvin D4, 10S, 17S-dihydroxy-docosapentaenoic acid, 15R-Lipoxin (LX)A4 and n-3 docosapentaenoic-derived Maresin 1 are predictive of DMARD responsiveness at 6 months. Assessment of circulating SPM concentrations 6-months after treatment initiation establishes that differences between responders and non-responders are maintained, with a decrease in SPM concentrations in patients resistant to DMARD therapy. These findings elucidate the potential utility of  plasma SPM concentrations as biomarkers of DMARD responsiveness in RA.

Associations between certolizumab pegol serum levels, anti-drug antibodies and treatment response in patients with inflammatory joint diseases: data from the NOR-DMARD study

OBJECTIVES

To identify a therapeutic target interval for certolizumab pegol drug levels and examine the influence of anti-drug antibodies in patients with inflammatory joint diseases.

METHODS

Certolizumab pegol and anti-drug antibody levels were measured in serum samples collected after 3 months of certolizumab pegol treatment in 268 patients with inflammatory joint diseases (116 axial spondyloarthritis, 91 rheumatoid arthritis and 61 psoriatic arthritis) in the NOR-DMARD study. Treatment response was defined by Ankylosing Spondylitis Disease Activity Score Clinically important improvement in axial spondyloarthritis, European League Against Rheumatism good/moderate response in rheumatoid arthritis, and improvement in 28-joint Disease Activity Score of ≥ 0.6 in PsA. Serum drug levels and anti-drug antibodies were analysed using automated in-house assays.

RESULTS

Certolizumab pegol serum levels varied considerably between individuals (median (IQR) 32.9 (17.3-43.9) mg/L). Certolizumab pegol level ≥ 20 mg/L was associated with treatment response for the total inflammatory joint disease population, with odds ratio (OR) 2.3 (95% CI 1.2-4.5, P = 0.01) and OR 1.9 (95% CI 1.0-3.5, P = 0.05) after 3 and 6 months of treatment, respectively. For individual diagnoses, this association was most consistent for axial spondyloarthritis, with OR 3.4 (95% CI 1.0-11.1, P < 0.05) and OR 3.3 (95% CI 1.0-10.8, P < 0.05), respectively. Certolizumab pegol level > 40 mg/L was not associated with any additional benefit for any of the diagnoses. Anti-drug antibodies were detected in 6.1% (19/310) of samples and were associated with low certolizumab pegol levels (P < 0.01).

CONCLUSIONS

Serum certolizumab pegol levels 20-40 mg/L were associated with treatment response in inflammatory joint diseases. Our study is the first to show this association in axial spondyloarthritis and psoriatic arthritis patients. The results suggest a possible benefit of therapeutic drug monitoring in patients with inflammatory joint disease on certolizumab pegol treatment.

TRIAL REGISTRATION

NCT01581294, April 2012.

Population Pharmacokinetics of Upadacitinib in Healthy Subjects and Subjects with Rheumatoid Arthritis: Analyses of Phase I and II Clinical Trials

Background and Objectives

Upadacitinib is a janus kinase (JAK) 1 inhibitor being developed for the treatment of rheumatoid arthritis (RA) and other inflammatory diseases. This work characterized upadacitinib population pharmacokinetics in healthy subjects and RA patients and the effects of covariates on upadacitinib exposure.

Methods

Upadacitinib plasma concentrations (n = 6399) from 107 healthy subjects and 466 RA patients from three phase I and two 12-week RA phase IIb trials (1–48 mg immediate-release doses across studies) were analyzed using non-linear mixed-effects modeling. The models were qualified using bootstrap and stochastic simulations.

Results

A two-compartment model with first-order absorption and elimination described upadacitinib pharmacokinetics. Estimates (95% bootstrap confidence interval) for upadacitinib oral clearance, steady-state volume of distribution, absorption lag time, and mean absorption time were 39.7 (37.8–41.5) L/h, 210 (196–231) L, 0.48 (0.47–0.49) h, and 0.08 (0.04–0.12) h, respectively, for a typical healthy male. Matching on other covariates, a 16 and 32% higher upadacitinib area under the concentration–time curve (AUC) was estimated for females relative to males, and for subjects with RA relative to healthy volunteers, respectively. Subjects with RA with mild or moderate renal impairment were estimated to have 16 and 32% higher upadacitinib AUC, respectively, compared with subjects with RA with normal renal function. Upadacitinib clearance was not correlated with body weight.

Conclusions

Upadacitinib pharmacokinetics follow dose-proportional, bi-exponential disposition. A slightly lower upadacitinib clearance is estimated in subjects with RA than in healthy volunteers, consistent with observations for other JAK inhibitors. Other covariates (weight, sex, mild or moderate renal impairment) are not associated with clinically relevant effects on upadacitinib exposure.

Trial Registration

ClinicalTrials.gov (https://clinicaltrials.gov/) identifiers: NCT01741493, NCT02066389, and NCT01960855.

Electronic supplementary material

The online version of this article (doi:10.1007/s40262-017-0605-6) contains supplementary material, which is available to authorized users.

Pharmacokinetics of ABT-122, a TNF-α- and IL-17A-Targeted Dual-Variable Domain Immunoglobulin, in Healthy Subjects and Patients with Rheumatoid Arthritis: Results from Three Phase I Trials

BACKGROUND AND OBJECTIVE

ABT-122 is a dual-variable domain immunoglobulin that neutralizes both tumor necrosis factor-α and interleukin-17A, with the goal of achieving greater clinical efficacy than can be achieved by blocking either cytokine alone. This work characterized the pharmacokinetics of ABT-122 in healthy subjects and in patients with rheumatoid arthritis.

METHODS

ABT-122 pharmacokinetics was evaluated in three phase I studies. In Study 1, single intravenous (0.1, 0.3, 1, 3, and 10 mg/kg) and subcutaneous (0.3, 1, and 3 mg/kg) doses were evaluated in healthy subjects. In Studies 2 and 3, multiple subcutaneous doses (1 mg/kg every other week or 0.5-3 mg/kg every week) were evaluated for 8 weeks in patients with rheumatoid arthritis on stable methotrexate therapy. Pharmacokinetic data were available from 48 healthy subjects and 31 patients with rheumatoid arthritis.

RESULTS

ABT-122 showed multi-exponential disposition with more than dose-proportional exposures at the 0.1-1 mg/kg doses and approximately dose-proportional exposures at doses ≥1 mg/kg. ABT-122 absolute subcutaneous bioavailability was approximately 50% with maximum serum concentrations observed 3-4 days after dosing. Steady state was achieved by week 6 of subcutaneous dosing. ABT-122 maximum serum concentration-to-trough concentration ratio was 2.6 for every other week dosing and 1.3 for every week dosing, corresponding to an effective half-life of 10-18 days. ABT-122 median area under the serum concentration-time curve accumulation ratio was 3.8-4.8 with every week dosing. Measureable antidrug antibodies were observed in all 48 subjects in Study 1 by day 15 post-dose and 19 of 31 ABT-122-treated patients in Studies 2 and 3 [median time to appearance of antidrug antibodies of 64 days (range 15-92 days)]. No dose-limiting toxicities were observed in these studies and the maximum tolerated dose was not identified.

CONCLUSIONS

Results from these three phase I studies supported testing ABT-122 every week and every other week regimens in phase II trials in subjects with rheumatoid and psoriatic arthritis. Study 2 (EudraCT: 2012-003448-54); Study 3 (NCT01853033).

Pharmacokinetics of Hydroxychloroquine in Pregnancies with Rheumatic Diseases

BACKGROUND

Hydroxychloroquine is an oral drug prescribed to pregnant women with rheumatic disease to reduce disease activity and prevent flares. Physiologic changes during pregnancy may substantially alter drug pharmacokinetics. However, the effect of pregnancy on hydroxychloroquine disposition and the potential need for dose adjustment remains virtually unknown.

METHODS

We performed a population-pharmacokinetic analysis using samples from the Duke Autoimmunity in Pregnancy Registry from 2013 to 2016. We measured hydroxychloroquine concentration using high-performance liquid chromatography/tandem mass spectrometry and analyzed data using non-linear mixed-effect modeling. We calculated differences between pregnancy and postpartum empirical Bayesian estimates using paired t tests. We computed steady-state concentration profiles for hydroxychloroquine during pregnancy and postpartum using individual clinical data and empirical Bayesian estimates developed from the final pharmacokinetic model.

RESULTS

We obtained 145 serum samples from 50 patients, 25 of whom had paired pregnancy and postpartum specimens. Five subjects had average concentrations (pregnancy and postpartum) < 100 ng/mL, consistent with medication non-adherence, and were excluded. The population estimated apparent volume of distribution was 1850 L/70 kg and estimated apparent clearance was 51 L/h. Compared with postpartum, median apparent volume of distribution increased significantly during pregnancy (p < 0.001), whereas apparent clearance and 24-h area under the curve did not change.

CONCLUSIONS

We developed a one-compartment population-pharmacokinetic model for hydroxychloroquine in pregnant women with rheumatic disease. Estimates for serum CL were within the expected range for plasma in non-pregnant adults. Because CL and 24-h area under the curve did not change during pregnancy compared with postpartum, our modeling in this small cohort does not support adjusting hydroxychloroquine dose during pregnancy.

The effect of methotrexate versus other disease-modifying anti-rheumatic drugs on serum drug levels and clinical response in patients with rheumatoid arthritis treated with tumor necrosis factor inhibitors

To investigate the effect of concomitant conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) with adalimumab or infliximab on maintaining serum drug and clinical outcomes after the first year of treatment in patients with rheumatoid arthritis (RA). Second, to assess the influence of methotrexate (MTX) dose on these outcomes. Ninety-two patients with RA starting infliximab (n = 67) or adalimumab (n = 25) tumor necrosis factor inhibitor (TNFi) with available drug levels and clinical improvement assessment (European League Against Rheumatism [EULAR] response) after 12 months were included. Patients were grouped according to concomitant csDMARD use: (i) TNFi monotherapy; (ii) TNFi+MTX; (iii) TNFi with csDMARDs other than MTX (TNFi+OD). Patients receiving MTX were also classified by dose as < 15 mg/week (TNFi+MTX<15) and ≥ 15 mg/week (TNFi+MTX≥15). Logistic regression analyses were employed. More TNFi+MTX patients had circulating serum TNFi at 12 months (71% TNFi+MTX vs. 20% TNFi+OD vs. 9% TNFi monotherapy). Of these, the probability of maintaining serum TNFi levels was twice (OR 2.3; p = 0.06) than that of patients without MTX. However, statistically significant results were observed only for the highest MTX dose (OR 4.9; p = 0.02). Most patients achieving good EULAR response were treated with TNFi+MTX (81%). The probability of achieving this response was three times higher in patients within the TNFi+MTX group (OR 3.4; p = 0.03); however, no differences were found with regard to MTX dose. The persistence of serum TNFi and the probability of achieving clinical response are influenced by MTX but not by OD in patients with RA treated with infliximab or adalimumab.

Lack of placental transfer of certolizumab pegol during pregnancy: results from CRIB, a prospective, postmarketing, pharmacokinetic study

OBJECTIVES

There is a need for effective and safe treatment during pregnancy in women with chronic inflammatory diseases. This study evaluated placental transfer of certolizumab pegol (CZP), an Fc-free anti-tumour necrosis factor drug, from CZP-treated pregnant women to their infants.

METHODS

CRIB was a pharmacokinetic (PK) study of women ≥30 weeks pregnant receiving commercial CZP for a locally approved indication (last dose ≤35 days prior to delivery). Blood samples were collected from mothers, umbilical cords and infants at delivery, and infants again at weeks 4 and 8 post-delivery. CZP plasma concentrations were measured with a highly sensitive and CZP-specific electrochemiluminescence immunoassay (lower limit of quantification 0.032 μg/mL).

RESULTS

Sixteen women entered and completed the study. Maternal CZP plasma levels at delivery were within the expected therapeutic range (median [range] 24.4 [5.0-49.4] μg/mL). Of the 16 infants, 2 were excluded from the per-protocol set: 1 due to missing data at birth and 1 due to implausible PK data. Of the remaining 14 infants, 13 had no quantifiable CZP levels at birth (<0.032 μg/mL), and 1 had a minimal CZP level of 0.042 μg/mL (infant/mother plasma ratio 0.0009); no infants had quantifiable CZP levels at weeks 4 and 8. Of 16 umbilical cord samples, 1 was excluded due to missing data; 3/15 had quantifiable CZP levels (maximum 0.048 μg/mL).

CONCLUSIONS

There was no to minimal placental transfer of CZP from mothers to infants, suggesting lack of in utero foetal exposure during the third trimester. These results support continuation of CZP treatment during pregnancy, when considered necessary.

TRIAL REGISTRATION NUMBER

NCT02019602; Results.

An exploratory study to determine whether infliximab modifies levels of rheumatoid factor and antibodies to cyclic citrullinated peptides in rheumatoid arthritis patients

OBJECTIVES

The aim of this study was to investigate the relationship between serum infliximab (IFX) levels and changes of RF and ACPA levels in patients with rheumatoid arthritis (RA).

METHODS

Enzyme-linked immunosorbent assays (ELISA) [Promonitor® IFX R1 (version 2) (Progenika Biopharma, Spain)] were used to measure drug levels and antidrug-antibodies (ADAb) in IFX RA-treated patients (n=19). Disease activity was assessed using DAS28. IgM rheumatoid factor (RF) and IgM, IgA and IgG anti-cyclic citrullinated peptide (ACPA) were determined through ELISA.

RESULTS

A significant decrease in RF (p=0.01), ACPA IgG (p=0.007), IgM (p=0.01) and IgA (p=0.03) was observed in patients presenting adequate levels of serum IFX. No significant changes to RF or ACPA were observed in patients with undetectable IFX.

CONCLUSIONS

Data from this study support the hypothesis that the anti-TNF antagonist IFX downregulates autoantibody levels in RA patients when IFX levels are detectable. Larger-scale studies need to be performed to establish RF and ACPA presence as therapeutic response predictive factors.

Improved adalimumab dose decision with comprehensive diagnostics data

OBJECTIVES

Monoclonal antibodies are important in the treatment of rheumatoid arthritis (RA). This is the first trial to monitor the effect of adalimumab dose escalation in persistently active RA. The aim of this study was to identify the response to adalimumab to improve the basis for making decision in relation to actual drug capacity in serum.

METHODS

The disease activity of RA patients was assessed with CDAI and DAS28 before administration of additional 40 mg adalimumab one week after standard injection. Serum samples were analysed using the recoveryELISA technology, a combination of sandwich ELISA and competitive assay. The recoveryELISA measure the concentrations of free TNF-α, drug level, and the remaining active adalimumab in the patients' sera. An adalimumab concentration of 5.0-10.0 g/mL was defined as the targeted therapeutic window.

RESULTS

Five of 8 patients achieved moderate EULAR response by dose escalation. The results of the free adalimumab and TNF-α neutralisation measurements allowed a separation of the cohort (n=17) into three groups. Group 1 represents 18% of the patients with free adalimumab level higher 30.0 μg/mL and TNF-α neutralisation above 95%. Group 2 (47%) consists of patients within the therapeutic window with balanced free adalimumab and TNF-α neutralisation values. Group 3 contains 35% of the cohort with low concentrations of free adalimumab and lowest remaining TNF-α-neutralisation capacity. Anti-drug antibodies were detected in four patients but did not prevent response to treatment.

CONCLUSIONS

Drug and antigen monitoring using recoveryELISA may support dose decision to avoid unnecessary switch in medication or possible overtreatment.

Optimal concentration range of golimumab in patients with axial spondyloarthritis

OBJECTIVES

To investigate the association between serum golimumab (GLM) trough levels, clinical disease activity and treatment response during the first year of therapy in patients with axial spondyloarthritis (axSpA), as well as determining an optimal concentration range of GLM in axSpA.

METHODS

This was an observational prospective study including 49 patients with axSpA monitored during 52 weeks (W52). Serum GLM trough levels were measured by capture ELISA and antidrug antibodies by bridging ELISA at baseline, W24 and W52. Disease activity was assessed by the Ankylosing Spondylitis Disease Activity Score (ASDAS) and clinical improvement by ΔASDAS. The association between serum GLM trough levels and disease activity was assessed using univariable and multivariable regression. In case of drop-out or missing data before W52, the last observation carried forward (LOCF) was performed. ASDAS values and GLM levels at W24 were available for 42 patients and 38 patients at W52.

RESULTS

In the univariable analyses, serum GLM trough levels were inversely associated with ASDAS at W24 (n=42, r =-0.445; p<0.01), at W52 (n=38, r=-0.330; p<0.05) and W52LOCF (n=49, r=-0.309; p<0.05). In the multivariable analysis, this significant association remained. Serum trough GLM levels above the 0.7-1.4mg/L range did not contribute to additional clinical improvement.

CONCLUSIONS

In patients with axSpA, serum GLM trough levels are associated with disease activity during the first year of treatment. A concentration range of 0.7-1.4mg/L appears to be useful to achieve clinical response to GLM.

Dried blood spots from finger prick facilitate therapeutic drug monitoring of adalimumab and anti-adalimumab in patients with inflammatory diseases

AIMS

Development of a self-sampling method for therapeutic drug monitoring (TDM) of biologicals will enhance TDM implementation in routine care and pharmacokinetic knowledge. The aim of this study was to compare adalimumab and anti-adalimumab antibody (ADA) concentration measurements in dried blood spots (DBS) obtained from finger prick with measurements in serum obtained via venepuncture, from patients with rheumatic inflammatory diseases.

METHODS

In this cross-sectional study, 161 consecutive patients were included. For clinical validation, DBS from finger prick and serum from venepuncture were collected simultaneously and adalimumab and ADA concentration were assessed by ELISA and antigen binding test (ABT), respectively. To convert DBS eluate results to values which can be compared to serum concentrations, five different methods were investigated, using a marker protein or a volumetric approach.

RESULTS

Adalimumab and ADA concentrations obtained from the finger prick/DBS method correlated well with serum results from the same patient (correlation coefficient > 0.87). Interestingly, antibody concentrations (either adalimumab, ADA or total immunoglobulin G) in DBS from finger prick, but not albumin, were systematically lower compared to serum. Spike experiments demonstrated a quantitative recovery for all tested proteins in DBS, suggesting a slightly different protein composition of blood collected via finger prick vs. venepuncture. We established a correction factor to relate finger prick/DBS values with serum values (approximately 1.2).

CONCLUSIONS

We show here for the first time that adalimumab and ADA serum concentrations can be satisfactorily estimated by measuring concentrations in DBS eluates, collected by finger prick. This method offers great opportunity to simplify TDM of adalimumab.

Pharmacokinetics of LBPT and its primary metabolites, as well as tolerability in the first-in-human study

BACKGROUND

LBPT is a novel platelet-activating factor (PAF) receptor antagonist that is developed for the treatment of rheumatoid arthritis. The purpose of this first-in-human study was to evaluate the tolerability and safety of LBPT, to investigate the pharmacokinetics of LBPT and its primary metabolites, as well as to assess the food effect on the pharmacokinetics in healthy Chinese subjects.

MATERIALS AND METHODS

LBPT was evaluated in 2 clinical studies. The first study was a double blind, placebo-controlled and ascending dose study. Eighty-five healthy Chinese subjects received oral dose of 2, 4, 6, 8, 15, 25, 50, 75, 100, 125, 150, 225, 300, 400 or 500mg of LBPT or placebo. The pharmacokinetics of LBPT and its primary metabolites were investigated in the last 4 dose cohorts. The tolerability was evaluated by monitoring adverse events (AEs), physical examinations, 12-lead electrocardiograms (ECG) and laboratory tests. The second study was an open-label, 2-period cross-over study with a washout interval of 3days. Twelve subjects received 300mg of LBPT after an overnight fasting or a high-fat breakfast. The pharmacokinetics of LBPT in subjects under fasted and fed conditions were compared.

RESULTS

LBPT was well tolerated up to 500mg-dose and there were no serious AEs in the study. The incidence and severity of AEs were closely related to dose. Following single oral administration of 225, 300, 400 and 500mg of LBPT, plasma C_max was reached at 0.5h and the mean t_1/2 was 0.6-1.6h. Plasma exposure increased with dose escalation but proportionality was not observed. LBPT was eliminated in forms of metabolites and 20-40% of the given dose was recovered in urine. Compared with the subjects under fasting conditions, AUC and C_max were lower and t_max was delayed in the fed subjects.

CONCLUSION

LBPT was well tolerated in healthy subjects with a pattern of dose-related AEs. The pharmacokinetics was non-linear and was impacted by food intake.

A randomised, single-blind, single-dose, three-arm, parallel-group study in healthy subjects to demonstrate pharmacokinetic equivalence of ABP 501 and adalimumab

OBJECTIVE

To demonstrate pharmacokinetic (PK) similarity of biosimilar candidate ABP 501 relative to adalimumab reference product from the USA and European Union (EU) and evaluate safety, tolerability and immunogenicity of ABP 501.

METHODS

Randomised, single-blind, single-dose, three-arm, parallel-group study; healthy subjects were randomised to receive ABP 501 (n=67), adalimumab (USA) (n=69) or adalimumab (EU) (n=67) 40 mg subcutaneously. Primary end points were area under the serum concentration-time curve from time 0 extrapolated to infinity (AUCinf) and the maximum observed concentration (Cmax). Secondary end points included safety and immunogenicity.

RESULTS

AUCinf and Cmax were similar across the three groups. Geometrical mean ratio (GMR) of AUCinf was 1.11 between ABP 501 and adalimumab (USA), and 1.04 between ABP 501 and adalimumab (EU). GMR of Cmax was 1.04 between ABP 501 and adalimumab (USA) and 0.96 between ABP 501 and adalimumab (EU). The 90% CIs for the GMRs of AUCinf and Cmax were within the prespecified standard PK equivalence criteria of 0.80 to 1.25. Treatment-related adverse events were mild to moderate and were reported for 35.8%, 24.6% and 41.8% of subjects in the ABP 501, adalimumab (USA) and adalimumab (EU) groups; incidence of antidrug antibodies (ADAbs) was similar among the study groups.

CONCLUSIONS

Results of this study demonstrated PK similarity of ABP 501 with adalimumab (USA) and adalimumab (EU) after a single 40-mg subcutaneous injection. No new safety signals with ABP 501 were identified. The safety and tolerability of ABP 501 was similar to the reference products, and similar ADAb rates were observed across the three groups.

TRIAL REGISTRATION NUMBER

EudraCT number 2012-000785-37; Results.

Obesity decreases clinical efficacy and levels of adalimumab in patients with ankylosing spondylitis

OBJECTIVES

Obesity can be a factor that affects response to anti-TNF drugs. However, studies on patients with ankylosing spondylitis (AS) are rare. We aimed to determine whether obesity affects serum levels of adalimumab (ADL), and immunogenicity and clinical efficacy of the drug in patients with AS.

METHODS

A cross-sectional study on 57 patients with axial AS receiving ADL was conducted. They received DMARD per standard of care at their rheumatologist's discretion. Patients' body mass index (BMI) was obtained when ADL treatment began. Clinical response was evaluated using the Spanish versions of the BASDAI index and the ASDAS ESR index. Serum concentrations of free ADL (trough level) and anti-ADL antibodies were measured using Promonitor-ADL and Promonitor Anti-ADL ELISA kits (Progenika Grifols SA, Spain), just prior to the next subcutaneous injection of ADL.

RESULTS

Patients with BMI >30 kg/ m2 (obese) as opposed to BMI <25 kg/ m2 (normal), presented lower blood ADL levels [5.0 (5.52) vs. 9.14 (4.3), p=0.032], increased ASDAS scores (2.58 [0.79] vs. 1.9 [0.83], p=0.03), and shorter ADL treatment time: 1.01 [0.84] vs. (1.85 [1.65]; p=0.08]), and increased BASDAI results (5.04 [2.5] vs. 3.5 [1.88]; p=0.06). Obese patients showed a lower probability of clinical response to ADL versus non-obese patients with regard to achieving BASDAI ≤4 (OR: 3.5, 95%CI: 0.84-17.19; p=0.05) or ASDAS ≤2.1 (OR: 4.64, 95%CI: 1.02-24.13; p=0.02).

CONCLUSIONS

Of the AS patients receiving treatment with ADL, those that are obese had significantly lower serum ADL levels and decreased clinical response without an increase in immunogenicity.

Optimizing biological treatment in rheumatoid arthritis with the aid of therapeutic drug monitoring

The treatment of rheumatoid arthritis (RA) has greatly improved with the use of biological TNF inhibitors (TNFi). These biopharmaceuticals target the inflammatory cytokine TNF, and hereby decrease the autoimmune inflammation, which may otherwise lead to permanent joint damage in the afflicted patients. Although TNFi decrease clinical disease activity in the majority of the treated patients, they are not always effective. Some patients have a partial response, some lose their initial response to treatment, and others never experience effect at all. The concentration of TNFi in the patients' bloodstreams, or the generation of antibodies directed towards the TNF inhibitor (anti-TNFi Abs), are known to have an impact on treatment efficacy. Furthermore, in patients with a good treatment response, strategies for how to tamper or discontinue treatment are lacking. In this PhD thesis, ways to improve treatment with TNFi are explored in three studies. The first study describe current knowledge on the effect of intensifying treatment with TNFi as a way to increase treatment efficacy. The results from this literature review do not convincingly support that intensified treatment increase efficacy in patients with RA in general, although an effect may be seen in patients treated with infliximab. The diverging results on the efficacy of infliximab intensification may be explained by effects on subgroups of patients being masked in mixed cohorts. We suspect that if patients are sub-grouped according to factors such as blood concentration of TNFi or presence of anti-TNFi Abs, an effect of treatment intensification on clinical outcome may bee more convincing. The second study assesses the frequency of anti-TNFi Ab formation in patients with RA in remission in an effort to identify patients for whom continued treatment is superfluous. If anti-TNFi Ab and low drug concentrations in patients in remission are predictors of TNFi-free remission, the impact on treatment and economic costs may be considerable. The finding that 10% of the patients in remission have developed anti-TNFi Abs shows that the potential is substantial. The third study investigates if baseline values of various biomarkers and other variables can predict development of anti-TNFi Abs or the emergence of sub-therapeutic drug levels. From the results, it seems that baseline inflammatory activity, judged from the level of interleukin-6 and possibly C-reactive protein, predicts low drug levels after six months of treatment. This may lead to early identification of patients at risk of treatment failure owing to inadequate drug levels, with the opportunity to take measures to prevent this.

[Clinical significance of serum C-C chemokine ligand 19 levels in patients with rheumatoid arthritis]

OBJECTIVE

To investigate the serum level of C-C chemokine ligand 19 (CCL19) and its clinical significance in rheumatoid arthritis.

METHODS

The serum CCL19 levels in both rheumatoid arthritis (RA) patients and health controls were detected by ELISA. The proportion of peripheral blood B cells and memory B cell subsets were also detected in some patients. Then the clinical and laboratory data of the patients were collected. The CCL19 levels in patients with different clinical features were analyzed. And the correlation between the clinical data, laboratory parameters, B cell subsets proportion and serum CCL19 levels were also analyzed. Independent samples t test, paired t test, Pearson and Spearman correlation were used for statistical analysis.

RESULTS

The levels of CCL19 was higher in the RA patients than the health controls (P<0.05). The serum CCL19 levels were decreased in the RA patients who accepted disease-modifying anti-rheumatic drugs (DMARDs) treatment for 6 months (P<0.001). Serum CCL19 levels were correlated with the titers of both rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibody (r=0.42, P=0.002; r=0.33, P=0.013), but not with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and disease activity score in 28 joints (DAS28) (P>0.05). The levels of CCL19 were higher in the serum positive (RF and anti-CCP antibody) patients, but there were no differences between low and high disease activity RA, as well as early and non-early RA. There was no correlation between the serum CCL19 levels and the proportion of B cells as well as memory B subsets. All the proportion of peripheral blood CD27+ memory B cell subsets in RA was lower than the healthy controls, including CD27+IgD+, CD27+IgD- and CD27+ B cells.

CONCLUSION

The increased serum CCL19 levels in RA patients are associated with the activity of B cells, so CCL19 might predict whether the RA type is a B cell mediated RA, and specify the treatment directions for the rheumatologist.

Comparing a tapering strategy to the standard dosing regimen of TNF inhibitors in rheumatoid arthritis patients with low disease activity

OBJECTIVES

The aim of this study is to compare clinical outcomes, incidence of flares and administered drug reduction between rheumatoid arthritis (RA) patients under TNF inhibitors (TNFi) tapering strategy and RA patients on standard regimen.

METHODS

Two groups of RA patients on TNFi with DAS28<3.2 were compared: the tapering group (TG: 67 pts from Spain) and the control group with standard therapy regimen (CG: 77 pts from the Netherlands). DAS28 was measured at different time points: visit 0 (prior starting TNFi), visit 1 (prior to start tapering in TG and with DAS28<3.2 in TG and CG), visit 2 (6 months after visit 1), visit 3 (1 year after visit 1), visit 4 (the last visit available after visit 1) and visit-flare (visit with the worst flare between visit 1 and visit 4).

RESULTS

Despite the reduction of administered drug at visit 4 in the TG (interval elongation of 32.8% in infliximab, 52.9% in adalimumab and 52.6% in etanercept), the DAS28 remained similar between groups at the end of the study (DAS28: 2.7±0.9 in TG vs. 2.5±1 in CG, p=0.1). No differences were seen in the number of patients with flares [26/67 (38.9%) in the TG vs. 30/77 (39%) in the CG, p=0.324] and only nineteen out of 136 patients (14%) had anti-drug antibodies at the end of the study.

CONCLUSIONS

The tapering strategy of TNFi in RA patients result in a reduction of the drug administered, while the disease control is not worse than patients on the standard regimen.

Quantification of Hydroxychloroquine in Blood Using Turbulent Flow Liquid Chromatography-Tandem Mass Spectrometry (TFLC-MS/MS)

Hydroxychloroquine (HQ) is used routinely in the treatment of autoimmune disorders such as rheumatoid arthritis and lupus erythematosus. Issues such as marked pharmacokinetic variability and patient non-compliance make therapeutic drug monitoring of HQ a useful tool for management of patients taking this drug. Quantitative measurements of HQ may aid in identifying poor efficacy as well as provide reliable information to distinguish patient non-compliance from refractory disease. We describe a rapid 7-min assay for the accurate and precise measurement of HQ concentrations in 100 μL samples of human blood using turbulent flow liquid chromatography coupled to tandem mass spectrometry. HQ is isolated from EDTA whole blood after a simple extraction with its deuterated analog, hydroxychloroquine-d4, in 0.33 M perchloric acid. Samples are then centrifuged and injected onto the TFLC-MS/MS system. Quantification is performed using a nine-point calibration curve that is linear over a wide range (15.7-4000 ng/mL) with precisions of <5 %.

A liquid chromatography-tandem mass spectrometry method for the quantitation of actarit in rabbit plasma: application to pharmacokinetics and metabolic stability

Actarit (ATR), 4-acetylaminophenylacetic acid is an orally effective disease-modifying anti-rheumatic drug widely prescribed for the treatment of rheumatoid arthritis. The present study demonstrates the first report on a selective and sensitive liquid chromatography-tandem mass spectrometry method for the quantification of ATR in rabbit plasma using p-coumaric acid as an internal standard (IS). Following liquid-liquid extraction, chromatographic separation of the reconstituted samples was achieved isocratically on a Syncronis-C18 column with a mobile phase consisting of aqueous ammonium acetate (10 mM, pH 4)- methanol and acetonitrile mixture (8 : 92, v/v) at a flow rate of 0.6 ml/min. ATR and IS were detected using electrospray ionization operated in negative multiple reaction monitoring mode. The calibration curve was linear (r(2)  ≥ 0.990) over the concentration range of 1-4000 ng/ml with a lower limit of quantitation of 1 ng/ml. The mean extraction recovery of ATR and IS from rabbit plasma was greater than 85%. The method complied well with US Food and Drug Administration guidelines for selectivity, sensitivity, accuracy, precision, matrix effect, dilution integrity, carry-over effect and stability. The method was successfully applied to in vitro metabolic stability (using rabbit liver microsomes) and in vivo pharmacokinetic study after oral administration of ATR at a dose of 10 mg/kg in New Zealand rabbits. Copyright © 2015 John Wiley & Sons, Ltd.

Agreement in assessment of infliximab and adalimumab levels in rheumatoid arthritis: interlaboratory and interassay comparison

OBJECTIVES

Infliximab (IFX) and adalimumab (ADL) drug levels and anti-drug antibodies (ADA) are assessed using a variety of techniques, therefore, results cannot accurately be compared for clinical purposes. The aim of this study was to test two infliximab (IFX) and adalimumab (ADL) ELISA versions, for drug levels and ADA, to see whether they yield similar results.

METHODS

ELISA versions [Promonitor® IFX R1 and R2 (V.1), Promonitor® IFX and Anti-IFX (V.2); Promonitor® ADL R1 and R2 (V.1), Promonitor® ADL and Anti-ADL (V.2) kits (Progenika Biopharma, Spain)] were used to measure drug levels and ADA in IFX (n=24) and ADL (n=24) rheumatoid arthritis-treated patients in three independent laboratories. Quantitative and qualitative agreements were evaluated using intraclass correlation coefficients (ICC), and Cohen's Kappa (κ) respectively. The Bland-Altman plots assessed differences between V.1 and V.2.

RESULTS

Interlaboratory agreement (ICC/κ) with V.1 was poor for IFX (0.66/0.62) and ADL (0.69/0.52) drug levels; meanwhile, high agreement was found with V.2 for IFX (0.98/0.95) and ADL (0.094/1.00). Comparison between V.1 and V.2 in each laboratory resulted in systematically higher values in V.2 than in V.1 and poor agreement (ICC/κ ranges) for IFX (0.12-0.7/ 0.19-0.42) and ADL (0.69-0.89 /0.50-0.73).

CONCLUSIONS

Qualitative measurements result in better agreement, as evidenced in our study. Greater agreement in V.2 compared with V.1 for IFX and ADL levels could be due to a better tune up. Further studies are required to standardise methods to establish therapeutic reference ranges.

Clinical relevance of monitoring serum levels of adalimumab in patients with rheumatoid arthritis in daily practice

OBJECTIVES

The aim of this paper is to assess the usefulness of measuring serum levels of adalimumab (ADL) and anti-ADL antibodies in 57 patients with rheumatoid arthritis (RA) treated with ADL for at least 3 months in daily practice.

METHODS

All patients received concomitant disease-modifying anti-rheumatic drug (DMARD). Receiver-operator characteristics (ROC) analysis was used to obtain the cut-off value of ADL for low disease activity (DAS28-ESR ≤3.2).

RESULTS

Anti-ADL antibodies were detected in 4 (7%) patients with a mean (SD) DAS28 score of 4.6 (0.9). Patients with positive anti-ADL antibodies had significantly lower levels of ADL and higher DAS28 scores than those with negative antibodies. Patients with DAS28 ≤3.2 as compared with patients with DAS28 >3.2 showed significantly better SDAI score, higher serum concentrations of ADL and none of them showed anti-ADL antibodies. The cut-off of serum level of ADL for DAS28 <3.2 was 4.3 mg/L. According to serum levels of ADL, patients were grouped into group 1 (low level) <5.5 mg/L, group 2 (medium level) 5.5-11.3 mg/L and group 3 (high level) >11.3 mg/L. Patients in the medium group were closed to clinical remission (median DAS28 2.7) and patients in the high group were on clinical remission (DAS28 2.1).

CONCLUSIONS

Serum levels of ADL should be maintained >4.3 mg/L. In patients with ADL levels >11.3 mg/L, a decrease of the dose of ADL or an increase in the interval between doses may be planned. The presence of anti-ADL antibodies was associated with a loss of clinical efficacy of ADL.

Therapeutic drug monitoring in rheumatic diseases: utile or futile?

Rapid and effective suppression of inflammation is a primary goal in the treatment of rheumatic diseases. However, the therapeutic effect of most medications may be slow to manifest, in the order of weeks or months in the case of DMARDs. Monitoring of drug concentrations allows the possibility of appropriate dose adjustment or changes in medication to achieve more rapid or better outcomes. We review the evidence for drug concentration monitoring. Despite the theoretical utility for monitoring of MTX polyglutamate concentrations in red blood cells in patients with RA, studies have not shown a clear association between concentrations and either efficacy or toxicity and routine measurement is not yet recommended. Small studies associating disease control with concentrations of anti-TNF therapies and anti-drug antibodies suggest that routine monitoring may be useful in the future. However, the data are not yet sufficient for this recommendation. With the use of allopurinol in gout, there is a putative therapeutic range for the active metabolite oxypurinol; however, adjusting the allopurinol dose to achieve a target urate concentration is likely to be most effective, and measuring oxypurinol may be best suited to assessing drug adherence. Although measuring thiopurine metabolite concentrations with AZA therapy has been shown to be useful in IBD, studies in rheumatic diseases have so far failed to confirm a useful association between concentrations and disease control or drug toxicity. Whole blood concentrations of HCQ have been associated with disease control in SLE and future studies may be able to determine a therapeutic range.

Subcutaneous administration of methotrexate with a prefilled autoinjector pen results in a higher relative bioavailability compared with oral administration of methotrexate

OBJECTIVES

Methotrexate (MTX) is recognised as the cornerstone of treatment for rheumatoid arthritis. For some patients, oral MTX demonstrates variable bioavailability, especially at higher doses. Such concerns may be mitigated by subcutaneous (SC) MTX administration. This study investigated the relative bioavailability, safety, and tolerability of MTX administered either by SC injection with a prefilled autoinjector pen (MTX pen) or orally.

METHODS

This single-centre, open-label, randomised, 2-period, 2-sequence, single-dose, crossover study enrolled healthy subjects aged 18 to 55 years into 1 of 4 dose groups (7.5 mg, 15 mg, 22.5 mg, and 30 mg), where they received a single dose of SC MTX and of the oral MTX tablets. Blood samples were collected from subjects predose and at prespecified time points postdose for pharmacokinetic analyses. Adverse events (AEs) were recorded to assess differences in safety and tolerability.

RESULTS

Bioavailability, as measured by maximum plasma concentrations (Cmax) and area under the plasma-concentration curves (AUC0-t), was generally higher with the SC MTX pen compared with oral administration for all dose groups. AUC0-t ratios increased with ascending doses; Cmax ratios did not increase. A total of 80 AEs were reported in 35/62 subjects; none were severe. Differences in the safety profiles were related to the route of administration. Single administrations with the MTX pen were well tolerated at the injection site.

CONCLUSIONS

Single-dose administration with the SC MTX pen resulted in a higher relative bioavailability compared with oral administration. SC MTX pen administration was associated with fewer gastrointestinal AEs than oral MTX.

Comparison of intracellular methotrexate kinetics in red blood cells with the kinetics in other cell types

AIM

To assess the similarities in intracellular pharmacokinetics (PK) of methotrexate (MTX) in red blood cells (RBCs) and other cell lines.

METHODS

Three previously published PK models for intracellular MTX and MTX polyglutamate (MTXGlu2-5 ) concentrations were used: (i) a model for the kinetics in RBCs, (ii) a model for the kinetics in human breast cancer cells (HBCCs) and (iii) a model for the kinetics in various white blood cell (WBC) lines. All three models were used to simulate the response in a typical individual receiving 10 mg oral MTX once weekly and the predicted steady-state concentrations (Css ) and time to Css (tss ) were compared.

RESULTS

The HBCC model showed a lower Css for MTXGlu2 and 3 and higher Css for MTXGlu4 and 5 compared with the RBC PK model, while tss and overall intracellular MTX exposure appeared similar. The WBC PK model showed much lower Css for the parent MTXGlu1 and of tss for all MTXGlun , as well as a much lower cumulative Css for MTXGlu2-7 for the majority of the WBC cell lines.

CONCLUSION

RBC kinetics of MTX differ from the kinetics in other cell types such as WBCs and HBCCs to a variable degree. It is possible that similarly diverse profiles may exist across other cell lines, including those on the causal path in rheumatoid arthritis. Hence, there may not necessarily be a clear link between RBC MTX concentrations and disease control in rheumatoid arthritis.

A novel dried blood spot-LCMS method for the quantification of methotrexate polyglutamates as a potential marker for methotrexate use in children

Objective

Development and validation of a selective and sensitive LCMS method for the determination of methotrexate polyglutamates in dried blood spots (DBS).

Methods

DBS samples [spiked or patient samples] were prepared by applying blood to Guthrie cards which was then dried at room temperature. The method utilised 6-mm disks punched from the DBS samples (equivalent to approximately 12 µl of whole blood). The simple treatment procedure was based on protein precipitation using perchloric acid followed by solid phase extraction using MAX cartridges. The extracted sample was chromatographed using a reversed phase system involving an Atlantis T3-C18 column (3 µm, 2.1×150 mm) preceded by Atlantis guard column of matching chemistry. Analytes were subjected to LCMS analysis using positive electrospray ionization.

Key Results

The method was linear over the range 5–400 nmol/L. The limits of detection and quantification were 1.6 and 5 nmol/L for individual polyglutamates and 1.5 and 4.5 nmol/L for total polyglutamates, respectively. The method has been applied successfully to the determination of DBS finger-prick samples from 47 paediatric patients and results confirmed with concentrations measured in matched RBC samples using conventional HPLC-UV technique.

Conclusions and Clinical Relevance

The methodology has a potential for application in a range of clinical studies (e.g. pharmacokinetic evaluations or medication adherence assessment) since it is minimally invasive and easy to perform, potentially allowing parents to take blood samples at home. The feasibility of using DBS sampling can be of major value for future clinical trials or clinical care in paediatric rheumatology.

A randomised, double-blind, parallel-group study to demonstrate equivalence in efficacy and safety of CT-P13 compared with innovator infliximab when coadministered with methotrexate in patients with active rheumatoid arthritis: the PLANETRA study

OBJECTIVES

To compare the efficacy and safety of innovator infliximab (INX) and CT-P13, an INX biosimilar, in active rheumatoid arthritis patients with inadequate response to methotrexate (MTX) treatment.

METHODS

Phase III randomised, double-blind, multicentre, multinational, parallel-group study. Patients with active disease despite MTX (12.5-25 mg/week) were randomised to receive 3 mg/kg of CT-P13 (n=302) or INX (n=304) with MTX and folic acid. The primary endpoint was the American College of Rheumatology 20% (ACR20) response at week 30. Therapeutic equivalence of clinical response according to ACR20 criteria was concluded if the 95% CI for the treatment difference was within ±15%. Secondary endpoints included ACR response criteria, European League Against Rheumatism (EULAR) response criteria, change in Disease Activity Score 28 (DAS28), Medical Outcomes Study Short-Form Health Survey (SF-36), Simplified Disease Activity Index, Clinical Disease Activity Index, as well as pharmacokinetic (PK) and pharmacodynamic (PD) parameters, safety and immunogenicity.

RESULTS

At week 30, ACR20 responses were 60.9% for CT-P13 and 58.6% for INX (95% CI -6% to 10%) in the intention-to-treat population. The proportions in CT-P13 and INX groups achieving good or moderate EULAR responses (C reactive protein (CRP)) at week 30 were 85.8% and 87.1%, respectively. Low disease activity or remission according to DAS28-CRP, ACR-EULAR remission rates, ACR50/ACR70 responses and all other PK and PD endpoints were highly similar at week 30. Incidence of drug-related adverse events (35.2% vs 35.9%) and detection of antidrug antibodies (48.4% vs 48.2%) were highly similar for CT-P13 and INX, respectively.

CONCLUSIONS

CT-P13 demonstrated equivalent efficacy to INX at week 30, with a comparable PK profile and immunogenicity. CT-P13 was well tolerated, with a safety profile comparable with that of INX. CLINICALTRIALS.GOV IDENTIFIER: NCT01217086.

A randomised, double-blind, multicentre, parallel-group, prospective study comparing the pharmacokinetics, safety, and efficacy of CT-P13 and innovator infliximab in patients with ankylosing spondylitis: the PLANETAS study

OBJECTIVES

To compare the pharmacokinetics (PK), safety and efficacy of innovator infliximab (INX) and CT-P13, a biosimilar to INX, in patients with active ankylosing spondylitis (AS).

METHODS

Phase 1 randomised, double-blind, multicentre, multinational, parallel-group study. Patients were randomised to receive 5 mg/kg of CT-P13 (n=125) or INX (n=125). Primary endpoints were area under the concentration-time curve (AUC) at steady state and observed maximum steady state serum concentration (Cmax,ss) between weeks 22 and 30. Additional PK, efficacy endpoints, including 20% and 40% improvement response according to Assessment in Ankylosing Spondylitis International Working Group criteria (ASAS20 and ASAS40), and safety outcomes were also assessed.

RESULTS

Geometric mean AUC was 32 765.8 μgh/ml for CT-P13 and 31 359.3 μgh/ml for INX. Geometric mean Cmax,ss was 147.0 μg/ml for CT-P13 and 144.8 μg/ml for INX. The ratio of geometric means was 104.5% (90% CI 94% to 116%) for AUC and 101.5% (90% CI 95% to 109%) for Cmax,ss. ASAS20 and ASAS40 responses at week 30 were 70.5% and 51.8% for CT-P13 and 72.4% and 47.4% for INX, respectively. In the CT-P13 and INX groups more than one adverse event occurred in 64.8% and 63.9% of patients, infusion reactions occurred in 3.9% and 4.9%, active tuberculosis occurred in 1.6% and 0.8%, and 27.4% and 22.5% of patients tested positive for anti-drug antibodies, respectively.

CONCLUSIONS

The PK profiles of CT-P13 and INX were equivalent in patients with active AS. CT-P13 was well tolerated, with an efficacy and safety profile comparable to that of INX up to week 30.

Pharmacokinetics and Safety of Golimumab, a Fully Human Anti-TNF-α Monoclonal Antibody, in Subjects With Rheumatoid Arthritis

Golimumab is a fully human antitumor necrosis factor alpha (TNF-alpha) monoclonal antibody that is being developed for intravenous and subcutaneous administration. To assess the pharmacokinetics and safety of the intravenous formulation of golimumab, 36 adult subjects with rheumatoid arthritis were randomly assigned to receive a single infusion of placebo or golimumab (0.1, 0.3, 1, 3, 6, or 10 mg/kg). Serum concentrations of golimumab were determined using a validated enzyme-linked immunosorbent assay method. In addition to the noncompartmental analysis and compartmental modeling, a population pharmacokinetics analysis using NONMEM was also conducted. Both the maximum serum concentration and the area under the serum concentrationtime curve appeared to increase in a dose-proportional manner. The median half-life ranged from 7 to 20 days. A 2-compartment population pharmacokinetic model adequately described the pharmacokinetics of golimumab. The following pharmacokinetic parameters (typical value [% coefficient of variation]) were estimated from the population pharmacokinetic model: clearance (CL: 0.40 [10.1%] L/d), volume of distribution in the central compartment (V(c): 3.07 [6.4%] L), intercompartmental clearance (Q: 0.42 [15.5%] L/d), and volume of distribution in the peripheral compartment (V(p): 3.68 [11.8%] L). Interindividual variability of the pharmacokinetic parameters was quantified for CL (44.3%), V(c) (25.5%), Q (44.6%), and V(p) (44.6%). Residual variability was estimated to be 15.0%. Body weight was found to be an important covariate on V(c). Golimumab was generally well tolerated. The pharmacokinetics of golimumab appeared to be linear over the dose range evaluated in this study.

A short-chain methotrexate polyglutamate as outcome parameter in rheumatoid arthritis patients receiving methotrexate

OBJECTIVES

Methotrexate (MTX) is a cornerstone in the treatment of rheumatoid arthritis (RA). Although in general MTX is very effective, the major drawback is the large inter-patient variability in clinical response. The circulating levels of MTX polyglutamates (MTXPGs) are supposed to correlate with clinical efficacy, therefore having a potential role in drug monitoring. However, there is a controversial discussion about the importance of methotrexate polyglutamates as outcome parameters in the therapy of rheumatoid arthritis. The aim of the present study was to investigate the formation and pharmacokinetics of MTXPGs and to correlate their concentration with clinical response in MTX-naïve patients.

METHODS

The pharmacokinetics of erythrocyte MTXPGs was determined in samples of nineteen MTX-naïve patients by high pressure liquid chromatography (HPLC) using post-column photo-oxidation and fluorimetric detection. The relationship between erythrocyte concentrations of MTXPGs and the primary outcome parameter DAS-28 was assessed using the Spearman's correlation coefficient.

RESULTS

The short-chain polyglutamate MTXPG2 revealed to be a potential marker for clinical outcome in rheumatoid arthritis with a statistically significant positive correlation of MTXPG2 Cmax levels and improvement in DAS-28 (+0.518, p=0.023) over 16 weeks. Furthermore, Cmax levels of MTXPG2 negatively correlated with basophils (-0.478, p=0.038) and eosinophils (-0.531, p=0.019), both pro-inflammatory cells involved in the disease.

CONCLUSIONS

MTXPG2 seems to be a potential indicator for clinical response and may serve as a marker for drug monitoring.

Patients non-responding to etanercept obtain lower etanercept concentrations compared with responding patients

Objective

To investigate the relationship between serum etanercept levels and clinical response.

Methods

In 292 etanercept-treated patients with rheumatoid arthritis clinical and pharmacological data were determined at baseline and after 1, 4 and 6 months of etanercept treatment. Differences in etanercept levels between good, moderate and European League Against Rheumatism (EULAR) non-responders were assessed after 6 months of therapy.

Results

After 6 months of therapy etanercept levels were significantly higher in good responders (median (IQR) 3.78 (2.53–5.17)) compared with both moderate 3.10 (2.12–4.47) and EULAR non-responders 2.80 (1.27–3.93) (all p<0.05). There was a significant association between clinical response and serum etanercept levels (regression coefficient 0.54, 95% CI 0.21 to 0.86, p=0.001). When patients were categorised into quartiles according to the height of etanercept levels, the lowest quartile (etanercept level <2.1 mg/l) comprised 40% of all non-responders. The highest quartile (etanercept level >4.7 mg/l) comprised 35% of all good EULAR responders. Anti-etanercept antibodies were detected in none of the sera.

Conclusion

The authors demonstrated that lower etanercept levels were associated with non-response. Therapeutic drug monitoring and the possibility of the adjusted dosing regimes in the selected groups of patients should be investigated further as a possible tool to optimise treatment with etanercept.

Antibodies toward infliximab are associated with low infliximab concentration at treatment initiation and poor infliximab maintenance in rheumatic diseases

INTRODUCTION

A proportion of patients receiving infliximab have antibodies toward infliximab (ATI), which are associated with increased risk of infusion reaction and reduced response to treatment. We studied the association of infliximab concentration at treatment initiation and development of ATI as well as the association of the presence of ATI and maintenance of infliximab.

METHODS

All patients with rheumatoid arthritis (RA) or spondyloarthritis (SpA) receiving infliximab beginning in December 2005 were retrospectively followed until January 2009 or until infliximab discontinuation. Trough serum infliximab and ATI concentrations were measured at each visit. The patients were separated into two groups: ATI(pos) if ATI were detected at least once during the follow-up period and ATI(neg) otherwise. Repeated measures analysis of variance was used to study the association of infliximab concentration at treatment initiation and the development of ATI. Maintenance of infliximab in the two groups was studied by using Kaplan-Meier curves.

RESULTS

We included 108 patients: 17 with RA and 91 with SpA. ATI were detected in 21 patients (19%). The median time to ATI detection after initiation of infliximab was 3.7 months (1.7 to 26.0 months). For both RA and SpA patients, trough infliximab concentration during the initiation period was significantly lower for ATI(pos) than ATI(neg) patients. RA patients showed maintenance of infliximab at a median of 19.5 months (5.0 to 31.0 months) and 12.0 months (2.0 to 24.0 months) for ATI(neg) and ATI(pos) groups, respectively (P = 0.08). SpA patients showed infliximab maintenance at a median of 16.0 months (3.0 to 34.0 months) and 9.5 months (3.0 to 39.0 months) for ATI(neg) and ATI(pos) groups, respectively (P = 0.20). Among SpA patients, those who were being treated concomitantly with methotrexate had a lower risk of developing ATI than patients not taking methotrexate (0 of 14 patients (0%) vs. 25 of 77 patients (32%); P = 0.03).

CONCLUSIONS

High concentrations of infliximab during treatment initiation reduce the development of ATI, and the absence of ATI may be associated with prolonged maintenance of infliximab. Thus, trough serum infliximab concentration should be monitored early in patients with rheumatic diseases.

Infliximab in ankylosing spondylitis: alone or in combination with methotrexate? A pharmacokinetic comparative study

INTRODUCTION

Methotrexate (MTX) has been shown to modify infliximab pharmacokinetics in rheumatoid arthritis. However, its combination with infliximab in the treatment of ankylosing spondylitis (AS) is not recommended. The objective of this study was to examine the influence of MTX on infliximab exposure in patients with AS.

METHODS

Patients with AS patients who had predominantly axial symptoms were randomised to receive infliximab alone (infusions of 5 mg/kg at weeks 0, 2, 6, 12 and 18) or infliximab combined with MTX (10 mg/week). Infliximab concentrations were measured before and 2 hours after each infusion and at 1, 3, 4, 5, 8, 10, 14 and 18 weeks. We estimated individual cumulative area under the concentration versus time curves (AUC) for infliximab concentration between baseline and week 18 (AUC(0-18)). Clinical and laboratory evaluations were performed at each visit. The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score was the primary end point for clinical response.

RESULTS

Twenty-six patients were included (infliximab group: n = 12, infliximab + MTX group: n = 14), and 507 serum samples were available for measurement of infliximab concentration. The two groups did not differ with regard to AUC(0-18) or evolution of BASDAI scores and biomarkers of inflammation.

CONCLUSIONS

The combination of MTX and infliximab does not increase the exposure to infliximab over infliximab alone in patients with AS.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00507403.

Methotrexate transport mechanisms: the basis for targeted drug delivery and ß-folate-receptor-specific treatment

Methotrexate (MTX) plays a pivotal role in the treatment of rheumatoid arthritis (RA). The transport mechanisms with which MTX reaches is target after application are an important part of MTX pharmacology and its concentration in target tissue such as RA synovial membrane might strongly influence the effectiveness of the drug. Physiological plasma protein binding of MTX to albumin is important for the distribution of MTX in the body and relative high concentrations of the drug are found in the liver. However, targeted drug delivery into inflamed joints and increased anti-arthritic efficiency can be obtained by covalent coupling of MTX ex-vivo to human serum albumin (MTX-HSA) or in-vivo to endogenous albumin mediated through the MTX-pro-drug AWO54. High expression of the folate receptor β (FR-β) on synovial macrophages of RA patients and its capacity to mediate binding and uptake of MTX has been demonstrated. To further improve drug treatment of RA, FR-β specific drugs have been developed and were characterised for their therapeutic potency in synovial inflammation. Therefore, different approaches to improve folate inhibitory and FR-β specific therapy of RA beyond MTX are in development and will be described.

Measuring methotrexate polyglutamates

Methotrexate is the most commonly used drug in the treatment of rheumatoid arthritis, although 30-40% of patients fail to adequately respond. An accurate method for measuring methotrexate polyglutamates, the stable active metabolite of methotrexate, has recently been described. The objective of this review article is to determine if clinical use of this measurement would improve methotrexate efficacy, or decrease adverse reactions. Additionally the pharmacologic rationale for this test is discussed. Although methotrexate response improves at higher methotrexate polyglutamate levels, there is no absolute correlation of level with effect. Moreover, overlapping methotrexate polyglutamate levels between clinical responders and nonresponders limits the clinical utility of this measurement.

Efficacy and safety of mizoribine by one single dose administration for patients with rheumatoid arthritis

OBJECTIVE

Mizoribine (MZR) is an immunosuppressant that inhibits nucleic acid metabolism and is a relatively safe disease-modifying anti-rheumatic drug (DMARD). We evaluated the efficacy and safety of one single dose per day for patients with rheumatoid arthritis (RA).

PATIENTS AND METHODS

In this study 32 patients with RA received MZR therapy. We evaluated the average dose of MZR and prednisolone, response to treatment and peak plasma level of MZR.

RESULTS

The average dose of MZR was 146.1±31.2 (range: 50-200) mg/day. The average dose of prednisolone was 4.63±3.59 (range: 0-14) mg/day. The average plasma level of MZR, measured after 3 hours, was 2.20±0.49 µg/mL in the responder group and 1.59±0.82 µg/mL in the non-responder group (p=0.020). The treatment with MZR for 24 weeks was completed by 71.9% of patients and the proportion of patients who achieved a good and moderate response rate according to the European League Against Rheumatism (EULAR) criteria was 56.3% at 24 weeks. The plasma level of MZR which was greater than or equal to 2.12 µg/mL was significantly correlated with the clinical response (p<0.01). Only one of thirty-two cases discontinued the treatment, because of skin eruption.

CONCLUSION

This study included patients that could not be treated with other DMARDs and/or biologic agents because of age, interstitial pneumonia and other complications. We show that MZR may be a useful and relatively safe therapy for patients in this group.

Bioassay for detection of methotrexate in serum

OBJECTIVE

A bioassay is developed for the measurement of methotrexate (MTX) in serum.

METHODS

The assay is based on MTX inhibition of the proliferation of hypoxanthine-guanosine phosphoribosyl transferase (HGPRT) negative mouse B-cells (B9.H). HGPRT negative cells cannot use the salvage pathway of nucleotide synthesis to overcome inhibition by MTX.

RESULTS

When B9.H cells are cultured with serial dilutions of serum, inhibition of proliferation is a measure of the amount of MTX in the serum. Circulating folates do not interfere with the assay.

CONCLUSION

This simple assay can detect low concentrations of MTX in serum: it is therefore useful for following the pharmacodynamics of functional MTX after low-dose MTX treatment.

No changes in infliximab levels in blood stored for preoperative autologous blood donation

Rheumatoid arthritis (RA) patients requiring total joint arthroplasties under administration of infliximab, which may remain in donated blood if preoperative autologous blood donation (PABD) is undertaken for the surgery, may risk infection. We clarified infliximab hemokinetics in blood stored for such patients. A 20-ml blood sample was obtained from each of the ten RA patients receiving infliximab at just after administration and at 2 and 4 weeks following the administration of infliximab, mixed with 2.8 ml citrate-phosphate-dextrose-adenine (CPDA-1) and stored at 4-6 degrees C. Plasma levels of infliximab in the stored blood were measured just after-mixture with CPDA-1, and at 2 and 4 weeks following the start of storage. Serum levels were also measured just before infliximab administration and at each phlebotomy. The plasma infliximab levels in the stored blood remained close to their original serum levels at the time of each corresponding phlebotomy, only somewhat influenced by dilution of CPDA-1, and sustained for 4 weeks following the start of storage, unlike in vivo, where levels decreased. This suggests that in order to prevent side effects, the later after infusion of infliximab the phlebotomy occurs, the better, and that the amount of stored blood transfusion should be consistent with that of blood loss.