Unaltered Etanercept Pharmacokinetics With Concurrent Methotrexate in Patients With Rheumatoid Arthritis

Population Pharmacokinetic Analysis and Simulation of Alternative Dosing Regimens for Biosimilars to Adalimumab and Etanercept in Patients with Rheumatoid Arthritis

Efficacy to biologics in rheumatoid arthritis (RA) patients is variable and is likely influenced by each patient's circulating drug levels. Using modelling and simulation, the aim of this study was to investigate whether adalimumab and etanercept biosimilar dosing intervals can be altered to achieve therapeutic drug levels at a faster/similar time compared to the recommended interval. RA patients starting subcutaneous Amgevita or Benepali (adalimumab and etanercept biosimilars, respectively) were recruited and underwent sparse serum sampling for drug concentrations. Drug levels were measured using commercially available kits. Pharmacokinetic data were analysed using a population approach (popPK) and potential covariates were investigated in models. Models were compared using goodness-of-fit criteria. Final models were selected and used to simulate alternative dosing intervals. Ten RA patients starting the adalimumab biosimilar and six patients starting the etanercept biosimilar were recruited. One-compartment PK models were used to describe the popPK models for both drugs; no significant covariates were found. Typical individual parameter estimates were used to simulate altered dosing intervals for both drugs. A simulation of dosing the etanercept biosimilar at a lower rate of every 10 days reached steady-state concentrations earlier than the usual dosing rate of every 7 days. Simulations of altered dosing intervals could form the basis for future personalised dosing studies, potentially saving costs whilst increasing efficacy.

A Quantitative Prediction Method for the Human Pharmacokinetics of Fc-Fusion Proteins

BACKGROUND AND OBJECTIVE

Fc fusion is an effective strategy for extending the half-lives of therapeutic proteins. This study aimed to evaluate the applicability of a human pharmacokinetics prediction method for Fc-fusion proteins by extending on reported methods for monoclonal antibodies (mAbs).

METHODS

To predict human pharmacokinetic profiles following intravenous (IV) dosing, the pharmacokinetic data for 11 Fc-fusion proteins in monkeys were analysed by two approaches: a species-invariant time method with a range of allometric exponents in clearance (CL, 0.7-1.0) and a two-compartment model reported for mAbs. The pharmacokinetic profiles following subcutaneous (SC) dosing were predicted by simple dose normalisation from monkeys or using the geometric means of the absorption rate constant (Ka) and bioavailability (BA) for mAbs or Fc-fusion proteins in humans and compared.

RESULTS

In the case of IV administration, the area under the curve could be predicted for more than 85% of Fc-fusion proteins within a twofold difference from the observed value using the species-invariant time method (scaling exponent for CL, 0.95). For SC dosing, incorporating the geometric means of absorption parameters for both mAbs (BA 68.2%, Ka 0.287 day-1) and Fc-fusion proteins (BA 63.0%, Ka 0.209 day-1) in humans provided better accuracy than simple normalisation from monkeys.

CONCLUSION

We have successfully predicted the human pharmacokinetic profiles of Fc-fusion proteins for both IV and SC administration within twofold of the observed value from monkey pharmacokinetic data by extending on reported methods for mAbs. This method will facilitate drug discovery and development of Fc-fusion proteins.

Etanercept for patients with juvenile idiopathic arthritis: drug levels and influence of concomitant methotrexate: observational study

BACKGROUND

Etanercept (ETN) is widely used tumour necrosis factor (TNF) blocker in the treatment of juvenile idiopathic arthritis (JIA) when traditional synthetic disease modifying antirheumatic drug (sDMARD) therapy is not sufficient. There is limited information about the effects of methotrexate (MTX) on serum ETN concentration in children with JIA. We aimed to investigate whether ETN dose and concomitant MTX would effect ETN serum trough levels in JIA patients, and whether concomitant MTX have an influence on the clinical response in patients with JIA receiving ETN.

METHODS

In this study, we collected the medical record data of 180 JIA patients from eight Finnish pediatric rheumatological centres. All these patients were treated with ETN monotherapy or combination therapy with DMARD. To evaluate the ETN concentrations, blood samples of the patients were collected between injections right before the subsequent drug. Free ETN level was measured from serum.

RESULTS

Ninety-seven (54%) of the patients used concomitant MTX, and 83 (46%) received either ETN monotherapy or used sDMARDs other than MTX. A significant correlation was noted between ETN dose and drug level [r = 0.45 (95% CI: 0.33-0.56)]. The ETN dose and serum drug level were correlated (p = 0.030) in both subgroups - in MTX group [r = 0.35 (95% CI: 0.14-0.52)] and in non-MTX group [r = 0.54 (95% CI: 0.39-0.67)].

CONCLUSION

In the present study, we found that concomitant MTX had no effect on serum ETN concentration or on clinical response. In addition, a significant correlation was detected between ETN dose and ETN concentration.

Serum etanercept concentrations in relation to disease activity and treatment response assessed by ultrasound, biomarkers and clinical disease activity scores: results from a prospective observational study of patients with rheumatoid arthritis

Objectives

To identify the therapeutic range for etanercept and to assess the incidence of anti-etanercept antibody formation.

Methods

Associations between etanercept serum concentration and disease activity as well as treatment response were examined in a longitudinal observational study of rheumatoid arthritis patients starting etanercept. Disease activity was assessed by ultrasound (grey scale and power Doppler), 28-joint Disease Activity Score (DAS28), Simplified Disease Activity Index, plasma calprotectin and C reactive protein. Etanercept concentration and anti-etanercept antibodies were analysed using automated in-house fluorescence assays.

Results

A total of 89 patients were included, whereof 66% were biological disease-modifying antirheumatic drug (DMARD) naïve and 91% used concomitant synthetic DMARD. At 3 months, the median etanercept concentration was 1.8 (IQR 1.1–2.5) mg/L. Longitudinal associations were found between etanercept concentration and disease activity assessed by plasma calprotectin, C reactive protein and DAS28, but not between etanercept concentration and improvement in disease activity by any of the parameters at 3, 6 or 12 months of treatment. Etanercept concentrations were not significantly different among patients who achieved response or remission, compared with non-response or non-remission. Hence, no therapeutic range could be identified. None of the patients developed anti-etanercept antibodies.

Conclusion

Despite the use of sensitive and objective markers of inflammation, a therapeutic range could not be identified for etanercept. Hence, this study suggests that proactive therapeutic drug monitoring is unlikely to benefit rheumatoid arthritis patients treated with etanercept, but a potential benefit in certain clinical situations cannot be excluded.

Methotrexate Reduces the Clearance of Adalimumab by Increasing the Concentration of Neonatal Fc Receptor in Tissues

PURPOSE

Although pharmacokinetic (PK) interaction effects of methotrexate (MTX) on adalimumab have been found, the mechanism of these effects is still unclear. In this work, effects of MTX on the concentration of neonatal Fc receptor (FcRn) and the role of FcRn in the interaction between MTX and adalimumab were investigated.

METHODS

The experiment was performed in rats whose FcRn had normal physiological function and also in rats whose FcRn was blocked with FcRn antibody. Rats were randomly assigned to receive placebo or 0.2 mg/kg MTX orally every week while taking one abdominal subcutaneous injection of 0.5 mg/kg adalimumab. The FcRn concentration in tissues and the PK parameters of adalimumab were compared between MTX-treated and placebo groups.

RESULTS

In rats with normally functioning FcRn, the concentrations of FcRn were significantly increased in the liver (F=105.5, p=0.000) and kidney (F=996.312, p=0.000) after treatment with MTX, and the clearance (CL/F) of adalimumab was decreased accordingly (F=4.423, p=0.048). However, in rats injected with FcRn antibody, the concentrations of FcRn in MTX-treated rats were close to that of the placebo rats in the tissues of the liver (F=1.279, p=0.268) and kidney (F=0.661, p=0.424). The CL/F of adalimumab in rats was also not affected by MTX (F=0.002, p=0.961).

CONCLUSIONS

FcRn may play a vital role in the interaction between adalimumab and MTX.

Intrapatient Variability in the Pharmacokinetics of Etanercept Maintenance Treatment

AIM

Etanercept has shown to mediate a favorable effect on immune-mediated inflammatory diseases (IMID), including plaque psoriasis. Therapeutic drug monitoring (TDM) of etanercept could improve clinical outcome and cost-effectiveness. A high intrapatient variability (IPV) of etanercept trough concentrations at standard dosing would reduce the feasibility of therapeutic drug monitoring. Studies have focused on the interpatient differences associated with the exposure to biologics. The aim of this study was to determine IPV of etanercept and correlate etanercept trough concentrations and IPV with treatment response.

METHODS

Repetitive serum samples of 29 psoriasis patients on standard etanercept maintenance treatment were collected. In these samples, etanercept trough concentrations were determined and IPV was assessed in relation to response to treatment.

RESULTS

The median IPV of etanercept trough concentrations was 33.7% (Q1 = 21.3% and Q3 = 51.7%) ranging from 8% to 155%. All 6 nonresponders showed an IPV at or above the median value of 33.7%. The 6 nonresponders showed a higher IPV as compared to the 23 responders (53.9% versus 24.2%; P = 0.031). The mean etanercept trough concentration for each patient ranged from 0.7 to 6.8 mcg/mL, with a median trough concentration of 2.7 mcg/mL. Patients with an IPV above the median had lower mean etanercept trough concentrations compared to patients with an IPV below the median (1.96 mcg/mL, 95% CI, 1.7-2.4 versus 3.2 mcg/mL, 95% CI, 2.7-4.0; P = 0.001).

CONCLUSIONS

The median IPV of etanercept trough concentrations in this study population was 33.7%. A higher IPV was correlated with lower etanercept trough concentrations and with nonresponsiveness. Prospective trials are required to demonstrate the value of adjusting the etanercept dose based on drug trough concentrations. The relatively high IPV observed in this study may complicate therapeutic drug monitoring.

Is there potential for therapeutic drug monitoring of biologic agents in rheumatoid arthritis?

The use of biologics has significantly changed the management of rheumatoid arthritis over the last decade, becoming the cornerstone treatment for many patients. The current therapeutic arsenal consists of just under 10 biologic agents, with four different mechanisms of action. Several studies have demonstrated a large interindividual pharmacokinetic variability, which translates to unpredictability in clinical response among individuals. The present review focuses on the pharmacokinetics and pharmacodynamics of biologic agents approved for rheumatoid arthritis. The literature relating to their concentration-effect relationship and the use of pharmacokinetic-pharmacodynamic modelling to optimize drug regimens is analysed. Due to the scarcity and complexity of these studies, the current dosing strategy is based on clinical indexes/aspects. In general, dose individualization for biologics should be implemented increasingly in clinical practice as there is a direct benefit for treated rheumatoid arthritis patients. Moreover, there is an indirect benefit in terms of cost-effectiveness.

Mechanism of Action, Pharmacokinetics, and Drug Interactions of Etanercept in Dermatology

Etanercept, a dimeric soluble form of the p75 tumor necrosis factor (TNF) receptor, has been shown to be efficacious for the treatment of psoriatic arthritis and moderate to severe chronic plaque psoriasis, as well as rheumatoid arthritis, juvenile rheumatoid arthritis, and ankylosing spondylitis. In this article, we review the mechanism of action, pharmacokinetics, and drug interactions of etanercept. Differences between etanercept and other anti-TNF antagonists with respect to membrane binding, the effect on T lymphocytes, the effect on the blood-brain barrier, adverse event profiles, and disease efficacy are also discussed.

Efficacy of etanercept in combination with methotrexate in moderate-to-severe rheumatoid arthritis is not dependent on methotrexate dosage

Objective

To evaluate the impact of methotrexate (MTX) dosage on clinical, functional and quality of life outcomes in patients with rheumatoid arthritis (RA) from two previous etanercept (ETN) trials after 24 months of treatment.

Methods

Patients with active RA in the ETN+MTX combination treatment arms of the Trial of Etanercept and Methotrexate with Radiographic Patient Outcomes (TEMPO) and COmbination of Methotrexate and ETanercept in Active Early Rheumatoid Arthritis (COMET) studies were pooled in this post hoc analysis and stratified by MTX dosage at 24 months, having MTX monotherapy groups as control: low dose, <10.0 mg/week; medium dose, 10.0–17.5 mg/week; and high dose, >17.5 mg/week. Data from these patient subgroups were included in descriptive summaries of demographic and disease characteristics at baseline. The following outcomes at 24 months were also evaluated for each subgroup: Disease Activity Score in 28 joints (DAS28) low disease activity (LDA) and remission; American College of Rheumatology 20%, 50% and 70% improvement criteria (ACR20, 50 and 70) responses; and changes from baseline in DAS28, Health Assessment Questionnaire Disease Index (HAQ-DI) and EuroQol 5-dimensions visual analogue scale (EQ-5D VAS).

Results

Baseline demographics were similar between the low, medium and high MTX dose groups in the ETN+MTX combination and MTX monotherapy arms, with the exception of disease duration (ETN+MTX low 5.5; medium 5.1; high 0.8 years vs MTX low 8.3; medium 4.7; high 0.8 years). Responses to ETN+MTX combination therapy at 24 months were consistently high across MTX dosage groups, with very similar rates of DAS28 LDA/remission and ACR20/50/70. Improvements in DAS28, HAQ-DI and EQ-5D VAS were also not dependent on MTX dosage in the combination treatment arm.

Conclusions

Patients with RA in the TEMPO and COMET trials who received ETN+MTX showed similar efficacy outcomes at 24 months, regardless of MTX dosage.

Trial registration numbers

NCT00195494 (COMET) and NCT00393471 (TEMPO).

Etanercept for the treatment of non-radiographic axial spondyloarthritis

Presently, tumor necrosis factor α antagonist therapy is the only effective alternative treatment to nonsteroidal anti-inflammatory drugs for the entire spectrum of axial spondyloarthritis, including non-radiographic and radiographic (=ankylosing spondylitis) forms. Recently, etanercept has been approved by the European Medicines Agency for the treatment of non-radiographic axial spondyloarthritis, increasing the number of available treatment options for this indication. The latest data on etanercept concerning clinical efficacy and safety in short-term and long-term treatment of patients with non-radiographic axial spondyloarthritis who do not respond to the first-line therapy with non-steroidal anti-inflammatory drugs suggests good efficacy and safety profiles similar to that observed previously in ankylosing spondylitis. This article reviews recent data on the efficacy and safety of etanercept and is focused on the treatment of non-radiographic axial spondyloarthritis. This article will also discuss the role of etanercept in the context of current and developing treatment options.

Clinical impact of concomitant immunomodulators on biologic therapy: Pharmacokinetics, immunogenicity, efficacy and safety

Immune-mediated inflammatory diseases encompass a variety of different clinical syndromes, manifesting as either common diseases such as rheumatoid arthritis (RA), inflammatory bowel disease (IBD) and psoriasis, or rare diseases such as cryopyrin-associated periodic syndromes. The therapy for these diseases often involves the use of a wide range of drugs including nonsteroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, immunomodulators, and biologic therapies. Due to the abundance of relevant clinical data, this article provides a general overview on the clinical impact of the concomitant use of immunomodulators and biologic therapies, with a focus on anti-tumor necrosis factor-α agents (anti-TNFα), for the treatment of RA and Crohn's disease (CD). Compared to biologic monotherapy, concomitant use of immunomodulators (methotrexate, azathioprine, and 6-mercaptopurine) often increases the systemic exposure of the anti-TNFα agent and decreases the formation of antibodies to the anti-TNFα agent, consequently enhancing clinical efficacy. Nevertheless, long-term combination therapy with immunomodulators and anti-TNFα agents may be associated with increased risks of serious infections and malignancies. Therefore, the determination whether combination therapy is suitable for a patient should always be based on an individualized benefit-risk evaluation. More research should be undertaken to identify and validate prognostic markers for predicting patients who would benefit the most and those who are at greater risk from combination therapy with immunomodulators and anti-TNFα agents.

The comparative safety of tumor necrosis factor inhibitors in rheumatoid arthritis: a meta-analysis update of 44 trials

OBJECTIVE

The study objective was to evaluate and update the safety data from randomized controlled trials of tumor necrosis factor inhibitors in patients treated for rheumatoid arthritis.

METHODS

A systematic literature search was conducted from 1990 to May 2013. All studies included were randomized, double-blind, controlled trials of patients with rheumatoid arthritis that evaluated adalimumab, certolizumab pegol, etanercept, golimumab, or infliximab treatment. The serious adverse events and discontinuation rates were abstracted, and risk estimates were calculated by Peto odds ratios (ORs).

RESULTS

Forty-four randomized controlled trials involving 11,700 subjects receiving tumor necrosis factor inhibitors and 5901 subjects receiving placebo or traditional disease-modifying antirheumatic drugs were included. Tumor necrosis factor inhibitor treatment as a group was associated with a higher risk of serious infection (OR, 1.42; 95% confidence interval [CI], 1.13-1.78) and treatment discontinuation due to adverse events (OR, 1.23; 95% CI, 1.06-1.43) compared with placebo and traditional disease-modifying antirheumatic drug treatments. Specifically, patients taking adalimumab, certolizumab pegol, and infliximab had an increased risk of serious infection (OR, 1.69, 1.98, and 1.63, respectively) and showed an increased risk of discontinuation due to adverse events (OR, 1.38, 1.67, and 2.04, respectively). In contrast, patients taking etanercept had a decreased risk of discontinuation due to adverse events (OR, 0.72; 95% CI, 0.55-0.93). Although ORs for malignancy varied across the different tumor necrosis factor inhibitors, none reached statistical significance.

CONCLUSIONS

These meta-analysis updates of the comparative safety of tumor necrosis factor inhibitors suggest a higher risk of serious infection associated with adalimumab, certolizumab pegol, and infliximab, which seems to contribute to higher rates of discontinuation. In contrast, etanercept use showed a lower rate of discontinuation. These data may help guide clinical comparative decision making in the management of rheumatoid arthritis.

Utility of population pharmacokinetic modeling in the assessment of therapeutic protein-drug interactions

Assessment of pharmacokinetic (PK) based drug-drug interactions (DDI) is essential for ensuring patient safety and drug efficacy. With the substantial increase in therapeutic proteins (TP) entering the market and drug development, evaluation of TP-drug interaction (TPDI) has become increasingly important. Unlike for small molecule (e.g., chemical-based) drugs, conducting TPDI studies often presents logistical challenges, while the population PK (PPK) modeling may be a viable approach dealing with the issues. A working group was formed with members from the pharmaceutical industry and the FDA to assess the utility of PPK-based TPDI assessment including study designs, data analysis methods, and implementation strategy. This paper summarizes key issues for consideration as well as a proposed strategy with focuses on (1) PPK approach for exploratory assessment; (2) PPK approach for confirmatory assessment; (3) importance of data quality; (4) implementation strategy; and (5) potential regulatory implications. Advantages and limitations of the approach are also discussed.

Therapeutic protein drug-drug interactions: navigating the knowledge gaps-highlights from the 2012 AAPS NBC Roundtable and IQ Consortium/FDA workshop

The investigation of therapeutic protein drug-drug interactions has proven to be challenging. In May 2012, a roundtable was held at the American Association of Pharmaceutical Scientists National Biotechnology Conference to discuss the challenges of preclinical assessment and in vitro to in vivo extrapolation of these interactions. Several weeks later, a 2-day workshop co-sponsored by the U.S. Food and Drug Administration and the International Consortium for Innovation and Quality in Pharmaceutical Development was held to facilitate better understanding of the current science, investigative approaches and knowledge gaps in this field. Both meetings focused primarily on drug interactions involving therapeutic proteins that are pro-inflammatory cytokines or cytokine modulators. In this meeting synopsis, we provide highlights from both meetings and summarize observations and recommendations that were developed to reflect the current state of the art thinking, including a four-step risk assessment that could be used to determine the need (or not) for a dedicated clinical pharmacokinetic interaction study.

Interactions among Low Dose of Methotrexate and Drugs Used in the Treatment of Rheumatoid Arthritis

Methotrexate (MTX) is a nonbiological disease-modifying antirheumatic drug that has shown both a good control of clinical disease and a good safety. Usually drug-drug interactions (DDIs) represent the most limiting factor during the clinical management of any disease, in particular when several drugs are coadministered to treat the same disease. In this paper, we report the interactions among MTX and the other drugs commonly used in the management of rheumatoid arthritis. Using Medline, PubMed, Embase, Cochrane libraries, and Reference lists, we searched for the articles published until June 30, 2012, and we reported the most common DDIs between MTX and antirheumatic drugs. In particular, clinically relevant DDIs have been described during the treatment with MTX and NSAIDs, for example, diclofenac, indomethacin, or COX-2 inhibitors, and between MTX and prednisone or immunosuppressant drugs (e.g., leflunomide and cyclosporine). Finally, an increase in the risk of infections has been recorded during the combination treatment with MTX plus antitumor necrosis factor-α agents. In conclusion, during the treatment with MTX, DDIs play an important role in both the development of ADRs and therapeutic failure.

Population-Based Assessments of Clinical Drug-Drug Interactions: Qualitative Indices or Quantitative Measures?

Population-based assessments of drug-drug interactions have become more common since the introduction and acceptance of the population pharmacokinetic approach. Unlike traditional methods, population-based studies provide clinically relevant results that can be applied directly to a target patient population. Furthermore, population-based studies do not demand the traditional requirements of intensive pharmacokinetic sampling, rigorous inpatient stays, or stringent assessment schedules. As such, the population-based approach can effectively be used to confirm known drug-drug interactions and further characterize anticipated interactions. A prospectively designed analysis can also reveal drug-drug interactions that might otherwise have gone undetected with traditional methods. Ultimately, these results could help to alleviate clinicians' concerns about using widely marketed drugs in combination therapies and also reduce patients' risk of experiencing unacceptable side effects. This article intends to provide a balanced overview of the population-based approach and its merits, drawbacks, and potential utility in the assessment of drug-drug interactions during clinical drug development.

Clinical Pharmacokinetics of Etanercept: A Fully Humanized Soluble Recombinant Tumor Necrosis Factor Receptor Fusion Protein

Etanercept, a fully humanized soluble recombinant tumor necrosis factor receptor fusion protein, is an approved treatment for rheumatoid arthritis, juvenile rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and psoriasis. Etanercept is absorbed slowly from the site of subcutaneous injection, with time to peak concentration at approximately 48 to 60 hours, and is cleared slowly from the body with a t(1/2) of 70 to 100 hours. The absolute bioavailability of etanercept was 58% in healthy subjects following subcutaneous administration. The 25-mg twice-weekly dosage regimen generates systemic exposures comparable to 50 mg once weekly, as predicted by pharmacokinetic modeling and simulation and later confirmed by clinical studies. The pharmacokinetics of etanercept in patients with rheumatoid arthritis are comparable to those in healthy individuals and patients with ankylosing spondylitis, congestive heart failure, and psoriasis. In children with polyarticular-course juvenile rheumatoid arthritis, after subcutaneous doses of 0.4 mg/kg twice weekly, the clearance of etanercept may be slightly reduced in children aged 4 to 8 years. Pharmacokinetic simulation predicts that a dose of 0.8 mg/kg once weekly generates comparable systemic exposure as 0.4 mg/kg twice weekly. No requirement for etanercept dosage adjustment is needed when etanercept is coadministered with warfarin, digoxin, or methotrexate.

Pharmacokinetic similarity of biologics: analysis using nonlinear mixed-effects modeling

Our objective was to show, using two examples, that a pharmacokinetic (PK) similarity analysis can be performed using nonlinear mixed-effects models (NLMEM). We used two studies that compared different biosimilars: a three-way crossover trial with somatropin and a parallel-group trial with epoetin-α. For both data sets, the results of NLMEM-based analysis were compared with those of noncompartmental analysis (NCA). For the latter analysis, we performed an NLMEM-based equivalence Wald test on secondary parameters of the model: the area under the curve and the maximal concentration. Somatropin PK was described by a one-compartment model and epoetin-α PK by a two-compartment model with linear and Michaelis-Menten elimination. For both studies, similarity of PK was demonstrated by means of both NCA and NLMEM, and both methods led to similar results. Therefore, for establishing similarity, PK data can be analyzed by either of the methods. NCA is an easier approach because it does not require data modeling; however, NLMEM leads to a better understanding of the underlying biological system.

Population pharmacokinetic and pharmacodynamic model-based comparability assessment of a recombinant human Epoetin Alfa and the Biosimilar HX575

The aim of this study was to develop an integrated pharmacokinetic and pharmacodynamic (PK/PD) model and assess the comparability between epoetin alfa HEXAL/Binocrit (HX575) and a comparator epoetin alfa by a model-based approach. PK/PD data-including serum drug concentrations, reticulocyte counts, red blood cells, and hemoglobin levels-were obtained from 2 clinical studies. In sum, 149 healthy men received multiple intravenous or subcutaneous doses of HX575 (100 IU/kg) and the comparator 3 times a week for 4 weeks. A population model based on pharmacodynamics-mediated drug disposition and cell maturation processes was used to characterize the PK/PD data for the 2 drugs. Simulations showed that due to target amount changes, total clearance may increase up to 2.4-fold as compared with the baseline. Further simulations suggested that once-weekly and thrice-weekly subcutaneous dosing regimens would result in similar efficacy. The findings from the model-based analysis were consistent with previous results using the standard noncompartmental approach demonstrating PK/PD comparability between HX575 and comparator. However, due to complexity of the PK/PD model, control of random effects was not straightforward. Whereas population PK/PD model-based analyses are suited for studying complex biological systems, such models have their limitations (statistical), and their comparability results should be interpreted carefully.

TNF alpha antagonist therapy and safety monitoring

OBJECTIVES

To develop and/or update fact sheets about TNFα antagonists treatments, in order to assist physicians in the management of patients with inflammatory joint disease.

METHODS

1. selection by a committee of rheumatology experts of the main topics of interest for which fact sheets were desirable; 2. identification and review of publications relevant to each topic; 3. development and/or update of fact sheets based on three levels of evidence: evidence-based medicine, official recommendations, and expert opinion. The experts were rheumatologists and invited specialists in other fields, and they had extensive experience with the management of chronic inflammatory diseases, such as rheumatoid. They were members of the CRI (Club Rhumatismes et Inflammation), a section of the Société Francaise de Rhumatologie. Each fact sheet was revised by several experts and the overall process was coordinated by three experts.

RESULTS

Several topics of major interest were selected: contraindications of TNFα antagonists treatments, the management of adverse effects and concomitant diseases that may develop during these therapies, and the management of everyday situations such as pregnancy, surgery, and immunizations. After a review of the literature and discussions among experts, a consensus was developed about the content of the fact sheets presented here. These fact sheets focus on several points: 1. in RA and SpA, initiation and monitoring of TNFα antagonists treatments, management of patients with specific past histories, and specific clinical situations such as pregnancy; 2. diseases other than RA, such as juvenile idiopathic arthritis; 3. models of letters for informing the rheumatologist and general practitioner; 4. and patient information.

CONCLUSION

These TNFα antagonists treatments fact sheets built on evidence-based medicine and expert opinion will serve as a practical tool for assisting physicians who manage patients on these therapies. They will be available continuously at www.cri-net.com and updated at appropriate intervals.

Bioequivalence tests based on individual estimates using non-compartmental or model-based analyses: evaluation of estimates of sample means and type I error for different designs

PURPOSE

The main objective of this work is to compare the standard bioequivalence tests based on individual estimates of the area under the curve and the maximal concentration obtained by non-compartmental analysis (NCA) to those based on individual empirical Bayes estimates (EBE) obtained by nonlinear mixed effects models.

METHODS

We evaluate by simulation the precision of sample means estimates and the type I error of bioequivalence tests for both approaches. Crossover trials are simulated under H ( 0 ) using different numbers of subjects (N) and of samples per subject (n). We simulate concentration-time profiles with different variability settings for the between-subject and within-subject variabilities and for the variance of the residual error.

RESULTS

Bioequivalence tests based on NCA show satisfactory properties with low and high variabilities, except when the residual error is high, which leads to a very poor type I error, or when n is small, which leads to biased estimates. Tests based on EBE lead to an increase of the type I error, when the shrinkage is above 20%, which occurs notably when NCA fails.

CONCLUSIONS

For small n or data with high residual error, tests based on a global data analysis should be considered instead of those based on individual estimates.

Etanercept in the treatment of plaque psoriasis

Etanercept is approved for the treatment of moderate to severe plaque psoriasis at a dose of 50 mg twice weekly for 3 months followed by a maintenance dosage of 50 mg weekly thereafter. Clinical studies have shown excellent efficacy, favorable benefit to side-effects ratio, and safe long-term usage. Extensive information on safety is available as etanercept has been used for many years for other indications such as rheumatoid arthritis and psoriatic arthritis and is the first of the tumor necrosis factor antagonists to gain approval in psoriasis.

Update on the natural history and systemic treatment of psoriasis

The onset of psoriatic disease and its associated comorbidities involves the interplay among a myriad of genetic and environmental risk factors. As we gain further insight into the immunopathogenesis of psoriasis, we hope it will provide the basis for the development of safer, more efficacious, and more durable therapeutics in the future. Given its enormous toll on patient health and quality of life, steps should be taken to prevent or decrease the risk for psoriasis-associated comorbidities through behavior modification and use of preventative health screenings and treatments. Future studies will need to be performed to determine if successful treatment of psoriasis will lead to a decreased risk for developing psoriasis-associated comorbidities over time.

Etanercept: long-term clinical experience in rheumatoid arthritis and other arthritis

Etanercept is a dimeric fusion protein based on the p75 TNF-alpha receptor. It binds to TNF-alpha and blocks its biologic activity. In randomized, double-blind, placebo-controlled trials, etanercept has therapeutic activity in rheumatoid arthritis, psoriatic arthritis, polyarticular-course juvenile idiopathic arthritis and ankylosing spondylitis. Etanercept improves joint inflammation, physical function and slows/halts structural damage, especially when combined with methotrexate. A sustained response is observed in a substantial percentage of patients. Although some safety issues should be considered before starting etanercept treatment, in general terms, etanercept is a well tolerated drug with an acceptable safety profile. The use of any TNF-alpha antagonist must be in agreement with the National Recommendations for Biologic Therapy, and in difficult clinical situations, a balance between risk/benefit needs to be obtained.

Recommendations for the use of etanercept in psoriasis: a European dermatology expert group consensus

BACKGROUND

Psoriasis is a chronic, inflammatory skin disorder that has a significant impact on quality of life and, particularly in moderate to severe cases, adversely affects the patient's overall health and well-being. Biological treatments, such as etanercept, are being widely adopted across Europe for treatment of moderate to severe psoriasis due to favourable safety and efficacy profiles. The increase in usage, combined with a growing body of clinical evidence, has identified a need to clarify the best use of etanercept within its current treatment label.

OBJECTIVE

To prepare a series of recommendations agreed by an expert group of dermatologists, relating to the most effective use of etanercept for psoriasis in Europe, within the product license.

METHODS

An expert panel of dermatologists from across Europe completed a Delphi survey to address the current use of etanercept in psoriasis in Europe. In June 2005 the results were presented to the expert panel at their nominal group meeting, and a consensus was agreed.

RESULTS

It was recommended that, where possible, patients are initiated on the 50 mg twice-weekly (BIW) dose. Etanercept should be given until remission is achieved (maximum 24 weeks) and retreatment should be initiated according to the physician's judgement. Before commencing treatment, contraindications, such as infection or previous malignancy (within 5 years), should be ruled out.

CONCLUSIONS

The consensus presented herein provides valuable clarification of use of etanercept according to the label, which may have wider implications relating to the use of all biological therapies in psoriasis.

Efficacy and safety of combination etanercept and methotrexate versus etanercept alone in patients with rheumatoid arthritis with an inadequate response to methotrexate: the ADORE study

OBJECTIVE

To evaluate the efficacy and safety of etanercept (ETN) monotherapy compared with combination ETN and methotrexate (MTX) treatment in patients with rheumatoid arthritis who had an inadequate response to MTX monotherapy. (The response was defined by the presence of Disease Activity Score-28 joint count (DAS28) >or=3.2 or a combination of >or=5 swollen joints, >or=5 painful joints and erythrocyte sedimentation rate >or=10 mm/h.)

METHODS

Patients with active rheumatoid arthritis taking MTX >or=12.5 mg/week for >or=3 months were included in this 16 week, randomised, open-label study. Patients were randomly assigned to either ETN (25 mg subcutaneous injection twice weekly) added to the baseline dose of MTX or ETN monotherapy.

RESULTS

315 patients were randomised to ETN (n = 160) or ETN plus MTX (n = 155). The primary end point, DAS28 (4) improvement of >1.2 units, was achieved by 72.8% and 75.2% of patients treated with ETN and those treated with ETN plus MTX, respectively, with no significant difference (p = 0.658) between the two groups. The European League Against Rheumatism response criteria of good or moderate response was attained by 80.0% of patients in the ETN group and by 82.4% of patients in the ETN plus MTX group. American College of Rheumatology 20%, 50% and 70% response rates achieved by both groups were also similar: 71.0% v 67.1%, 41.9% v 40.1% and 17.4% v 18.4%, respectively. The rates of adverse and serious adverse events were similar between the treatment groups.

CONCLUSION

Both the addition of ETN to MTX and the substitution of ETN for MTX in patients with rheumatoid arthritis who had an inadequate response to MTX resulted in substantial improvements in clinical signs and symptoms and were generally well-tolerated treatment strategies for improving clinical signs and symptoms of rheumatoid arthritis.

The comparability of etanercept pharmacokinetics in healthy Japanese and American subjects

Thirty Japanese (J) and 32 American (A) healthy subjects received single doses of etanercept by subcutaneous injection, in 3 separate trials. Serum samples were collected for 480 hours after dosing. Concentrations were determined using enzyme-linked immunosorbent assay methods. Pharmacokinetic parameters were calculated using both non-compartmental and compartmental methods. Etanercept was slowly absorbed, with mean+/-SD time to maximum serum concentration of 47+/-15 hours (J), and 51+/-20 hours (A). The maximum serum concentration and area under the concentration time curve increased for doses 10 mg, 25 mg, and 50 mg, in a linear relationship. Etanercept was slowly eliminated, with observed mean+/-SD half-life of 80+/-25 hours (J) and 75+/-15 hours (A) and mean+/-SD apparent clearance of 144+/-65 mL/h (J) and 132+/-74 mL/h (A). Very low concentrations of etanercept were observed in the urine samples collected in the Japanese subjects. All adverse reactions observed resolved without issue, and none required discontinuation from the study.

InforMatrix: treatment of rheumatoid arthritis using biologicals

This article offers an interactive decision matrix technique (InforMatrix), in which a group of experts in rheumatology determine an order of merit within the various biologicals used for rheumatoid arthritis. In this order of merit, six criteria (efficacy, safety, tolerance, ease of use, applicability and costs) are weighed against each other. Data necessary for this weighing process are derived from both literature, as well as clinical practice experience. This article provides an overview of the most relevant clinical trials on the biologicals, as well as a description of the interactive decision matrix technique. Using this interactive matrix technique makes rational consideration of the treatment options for rheumatoid arthritis possible.

[A case of recurrent breast cancer with life-threatening multiple lung metastasis markedly responding to CMF as third-line chemotherapy]

A 35-year-old woman with taxane and anthracycline-resistant recurrent breast cancer with multiple lung metastasis and carcinomatous lymphangitis was treated with CMF as third-line chemotherapy. A complete response was achieved,and the toxicities were tolerable. We thought that CMF could be a useful regimen as third-line chemotherapy for metastatic breast cancer.