Vagus nerve stimulation inhibits cytokine production and attenuates disease severity in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a heterogeneous, prevalent, chronic autoimmune disease characterized by painful swollen joints and significant disabilities. Symptomatic relief can be achieved in up to 50% of patients using biological agents that inhibit tumor necrosis factor (TNF) or other mechanisms of action, but there are no universally effective therapies. Recent advances in basic and preclinical science reveal that reflex neural circuits inhibit the production of cytokines and inflammation in animal models. One well-characterized cytokine-inhibiting mechanism, termed the "inflammatory reflex," is dependent upon vagus nerve signals that inhibit cytokine production and attenuate experimental arthritis severity in mice and rats. It previously was unknown whether directly stimulating the inflammatory reflex in humans inhibits TNF production. Here we show that an implantable vagus nerve-stimulating device in epilepsy patients inhibits peripheral blood production of TNF, IL-1ß, and IL-6. Vagus nerve stimulation (up to four times daily) in RA patients significantly inhibited TNF production for up to 84 d. Moreover, RA disease severity, as measured by standardized clinical composite scores, improved significantly. Together, these results establish that vagus nerve stimulation targeting the inflammatory reflex modulates TNF production and reduces inflammation in humans. These findings suggest that it is possible to use mechanism-based neuromodulating devices in the experimental therapy of RA and possibly other autoimmune and autoinflammatory diseases.

[VAGAL NERVE STIMULATION IN THE TREATMENT OF PATIENTS WITH RHEUMATOID ARTHRITIS ­ RESULTS THROUGH DAY 84 OBTAINED AT THE CROATIAN CENTER OF AN INTERNATIONAL PILOT STUDY].

Objective: Electrical stimulation of the vagus has proven effective in various inflammatory conditions in animal models. The aim of this study is to show the effect of vagal nerve neurostimulation on clinical and laboratory parameters in two patients with active rheumatoid arthritis (RA) and an inadequate response to methotrexate. Patients and methods: The research was conducted as part of an international pilot study. Patients were implanted with the Cyberonics system for electrical stimulation of the vagus. After an initial in-clinic stimulation, the patients performed the stimulations at home for 42 days, when the device was inactivated. On day 56 the stimulations were reinitiated. The following parameters were evaluated: tender and swollen joint count, physician's (PGA) and patient's (PtGA) global score, intensity of pain, disease activity (DAS28), functional ability (HAQ), serum CRP level, and EULAR response. Results: In the period from the screening visit to the day 42 visit, both patients experienced an improvement of DAS28 (7.00 and 6.22 vs. 4.03 and 2.13), PGA (70 and 53 vs. 27 and 16), PtGA (48 and 43 vs. 15 and 14), tender joint count (26 and 28 vs. 4 and 0), swollen joint count (24 and 14 vs. 8 and 2), intensity of pain (72 and 87 vs 21 and 7), HAQ score (2.25 and 2.25 vs. 1.5 and 1.375), and CRP levels (23.8 and 5.58 vs. 13 and 4.61). After the device deactivation, DAS28 and VAS pain worsened in both patients. Conclusion: Vagal neural stimulation in the treatment of patients with active RA and an inadequate response to methotrexate is effective in reducing clinical symptoms and parameters of inflammation. Our results are in accordance with the results obtained in other centers. Research on a larger number of subjects is necessary for a better evaluation of the effect of this new approach to the treatment of patients with rheumatoid arthritis.

Lebrikizumab in Uncontrolled Asthma: Reanalysis in a Well-Defined Type 2 Population.

BACKGROUND: LAVOLTA (L)I, LII, and ACOUSTICS were randomized, placebo-controlled, Phase 3 trials of lebrikizumab, a monoclonal antibody targeting IL-13 in patients with uncontrolled asthma. Failure to demonstrate efficacy may have been related to patient selection in those trials. OBJECTIVE: To assess the efficacy in a well-defined subpopulation of patients with elevated blood eosinophil counts and a minimum number of prior asthma exacerbations. We performed an additional analysis in a subpopulation of patients with elevated FeNO and prior exacerbations. METHODS: Adult (LI and LII) and adolescent patients (aged 12-17 years weighing ≥40 kg, ACOUSTICS) with uncontrolled asthma received lebrikizumab (125 mg, n = 832; or 37.5 mg, n = 829) or placebo (n = 833) subcutaneously every 4 weeks. Post hoc analysis of the annualized adjusted exacerbation rate (AER) was performed in a subpopulation of patients with baseline blood eosinophils of 300 cells/µL or greater and history of one or more exacerbations. In this subpopulation, there were 227 patients in the placebo group, 222 in the lebrikizumab 37.5-mg group, and 217 in the lebrikizumab 125-mg group. We summarized safety in patients who received at least one dose of lebrikizumab using adverse events. RESULTS: Lebrikizumab significantly reduced AER compared with placebo in adults (AER reduction: 125 mg [38%]; and 37.5 mg [41%]) and adolescents (AER reduction:125 mg [59%]; 37.5 mg [64%]) with baseline blood eosinophils of 300 cells/µL or greater and one or more exacerbations. Most adverse events were mild or moderate in severity and did not lead to treatment discontinuation. CONCLUSION: Lebrikizumab significantly reduced asthma exacerbations in a subpopulation of patients with elevated blood eosinophils, elevated FeNO, and a history of asthma exacerbation.

Neuroimmune Modulation Through Vagus Nerve Stimulation Reduces Inflammatory Activity in Crohn's Disease Patients: A Prospective Open-label Study.

BACKGROUND AND AIMS: Crohn's disease [CD] is a debilitating, inflammatory condition affecting the gastrointestinal tract. There is no cure and sustained clinical and endoscopic remission is achieved by fewer than half of patients with current therapies. The immunoregulatory function of the vagus nerve, the 'inflammatory reflex', has been established in patients with rheumatoid arthritis and biologic-naive CD. The aim of this study was to explore the safety and efficacy of vagus nerve stimulation in patients with treatment-refractory CD, in a 16-week, open-label, multicentre, clinical trial. METHODS: A vagus nerve stimulator was implanted in 17 biologic drug-refractory patients with moderately to severely active CD. One patient exited the study pre-treatment, and 16 patients were treated with vagus nerve stimulation [4/16 receiving concomitant biologics] during 16 weeks of induction and 24 months of maintenance treatment. Endpoints included clinical improvement, patient-reported outcomes, objective measures of inflammation [endoscopic/molecular], and safety. RESULTS: There was a statistically significant and clinically meaningful decrease in CD Activity Index at Week 16 [mean ±â€…SD: -86.2 ±â€…92.8, p = 0.003], a significant decrease in faecal calprotectin [-2923 ±â€…4104, p = 0.015], a decrease in mucosal inflammation in 11/15 patients with paired endoscopies [-2.1 ±â€…1.7, p = 0.23], and a decrease in serum tumour necrosis factor and interferon-γ [46-52%]. Two quality-of-life indices improved in 7/11 patients treated without biologics. There was one study-related severe adverse event: a postoperative infection requiring device explantation. CONCLUSIONS: Neuroimmune modulation via vagus nerve stimulation was generally safe and well tolerated, with a clinically meaningful reduction in clinical disease activity associated with endoscopic improvement, reduced levels of faecal calprotectin and serum cytokines, and improved quality of life.

Treatment of chronic inflammatory diseases with implantable medical devices.

Implantable medical devices are finding increasing use in the treatment of diseases traditionally targeted with drugs. It is well established that the cholinergic anti-inflammatory pathway serves as a physiological regulator of inflammatory responses, but stimulation of this pathway therapeutically by electrical stimulation of the vagus nerve can also diminish excessive or dysregulated states of inflammation. Recent data from a wide variety of animal models, as well as evidence of reduced vagal tone in rheumatoid arthritis and other inflammatory diseases, support the rationale for, and feasibility of, developing implantable vagal nerve stimulation devices to treat chronic inflammation in humans.

Etanercept and clinical outcomes, fatigue, and depression in psoriasis: double-blind placebo-controlled randomised phase III trial.

BACKGROUND: Psoriasis has substantial psychological and emotional effects. We assessed the effect of etanercept, an effective treatment for the clinical symptoms of psoriasis, on fatigue and symptoms of depression associated with the condition. METHODS: 618 patients with moderate to severe psoriasis received double-blind treatment with placebo or 50 mg twice-weekly etanercept. The primary efficacy endpoint was a 75% or greater improvement from baseline in psoriasis area and severity index score (PASI 75) at week 12. Secondary and other endpoints included the functional assessment of chronic illness therapy fatigue (FACIT-F) scale, the Hamilton rating scale for depression (Ham-D), the Beck depression inventory (BDI), and adverse events. Efficacy analyses were based on the allocated treatment. Analyses and summaries of safety data were based on the actual treatment received. This study is registered with with the identifier NCT00111449. FINDINGS: 47% (147 of 311) of patients achieved PASI 75 at week 12, compared with 5% (15 of 306) of those receiving placebo (p<0.0001; difference 42%, 95% CI 36-48). Greater proportions of patients receiving etanercept had at least a 50% improvement in Ham-D or BDI at week 12 compared with the placebo group; patients treated with etanercept also had significant and clinically meaningful improvements in fatigue (mean FACIT-F improvement 5.0 vs 1.9; p<0.0001, difference 3.0, 95% CI 1.6-4.5). Improvements in fatigue were correlated with decreasing joint pain, whereas improvements in symptoms of depression were less correlated with objective measures of skin clearance or joint pain. INTERPRETATION: Etanercept treatment might relieve fatigue and symptoms of depression associated with this chronic disease.

Etanercept as monotherapy in patients with psoriasis.

BACKGROUND: Inflammatory cytokines such as tumor necrosis factor (TNF) have been implicated in the pathogenesis of psoriasis. We evaluated the safety and efficacy of etanercept, a TNF antagonist, for the treatment of plaque psoriasis. METHODS: In this 24-week, double-blind study, 672 patients underwent randomization and 652 either received placebo or received etanercept subcutaneously at a low dose (25 mg once weekly), a medium dose (25 mg twice weekly), or a high dose (50 mg twice weekly). After 12 weeks, patients in the placebo group began twice-weekly treatment with 25 mg of etanercept. The primary measure of clinical response was the psoriasis area-and-severity index. RESULTS: At week 12, there was an improvement from base line of 75 percent or more in the psoriasis area-and-severity index in 4 percent of the patients in the placebo group, as compared with 14 percent of those in the low-dose--etanercept group, 34 percent in the medium-dose--etanercept group, and 49 percent in the high-dose-etanercept group (P<0.001 for all three comparisons with the placebo group). The clinical responses continued to improve with longer treatment. At week 24, there was at least a 75 percent improvement in the psoriasis area-and-severity index in 25 percent of the patients in the low-dose group, 44 percent of those in the medium-dose group, and 59 percent in the high-dose group. The responses as measured by improvements in the psoriasis area-and-severity index were paralleled by improvements in global assessments by physicians and the patients and in quality-of-life measures. Etanercept was generally well tolerated. CONCLUSIONS: The treatment of psoriasis with etanercept led to a significant reduction in the severity of disease over a period of 24 weeks.

Modeling the exposure-response relationship of etanercept in the treatment of patients with chronic moderate to severe plaque psoriasis.

Modeling exposure-response relationships adds significant value to comprehending and interpreting both efficacy and safety data. An exposure-response model was developed using generalized nonlinear mixed-effects methodologies to correlate etanercept exposure with a 75% or greater reduction from baseline in the psoriasis area and severity index (PASI75). Three randomized trials of psoriasis patients were pooled for analysis. Three empirical exposure measures-cumulative dose, predicted cumulative area under the curve, and predicted trough concentration-were evaluated for their predictive capabilities. The predicted cumulative area under the curve model demonstrated the best ability via simulation to reproduce the data and was used to assess the following covariates: age, baseline psoriasis area and severity index, duration of psoriasis disease, prior systemic or phototherapy, race, sex, and weight. The final model was composed by scrutinizing the confidence intervals of a nonparametric bootstrap and included race and sex effects on baseline logit, baseline psoriasis area and severity index and prior systemic or phototherapy effects on maximum drug effect, a weight effect on apparent potency, and an age effect on the rate of drug effect. The model identified covariates predictive of data trends and adequately characterized by simulation the PASI75 over the entire clinical trial design space. In combination with a statistical subgroup analysis, the exposure-response model indicated that dose adjustment was not necessary for etanercept in any patient subpopulation with moderate to severe plaque psoriasis.

Patients with psoriasis respond to continuous open-label etanercept treatment after initial incomplete response in a randomized, placebo-controlled trial.

BACKGROUND: Etanercept provides rapid, significant improvement in psoriatic symptoms and disease. OBJECTIVE: The effectiveness of continued etanercept treatment beyond 24 weeks in patients who initially did not achieve at least a 50% improvement from baseline in the Psoriasis Area and Severity Index (PASI 50) was assessed. METHODS: Patients with moderate to severe plaque psoriasis received 50 mg open-label, subcutaneous etanercept per week after completing blinded therapy with placebo or 1 of 3 doses of etanercept. The PASI was measured. RESULTS: Irrespective of prior dosing regimens, 43% of 157 patients who did not attain PASI 50 responses at week 24 achieved PASI 50 responses at week 36; 55% achieved PASI 50 responses at week 60. Etanercept was safe and well tolerated. LIMITATIONS: Interpretation of these results is limited by the open-label design of the analysis. CONCLUSION: More than half of patients who initially had an inadequate response to treatment achieved satisfactory responses with continued etanercept therapy. The safety profile of etanercept in these patients and in patients who had more immediate responses was similar.

Efficacy of etanercept in an integrated multistudy database of patients with psoriasis.

BACKGROUND: The tumor necrosis factor (TNF) inhibitor etanercept has been demonstrated to be safe and effective for treating chronic plaque psoriasis in 3 clinical trials. OBJECTIVES: To refine efficacy results for etanercept on the basis of a larger population size through the integration of the 3 studies, and to determine if the efficacy profile across all 3 studies is consistent with efficacy profiles observed for individual trials. METHODS: In these integrated analyses, data for 1187 patients from 3 blinded treatment groups were pooled to compare efficacy at 12 weeks: etanercept 50 mg weekly (equivalent to 25 mg twice weekly) subcutaneously, etanercept 50 mg twice weekly subcutaneously, and placebo. The primary efficacy end point in all 3 studies was at least a 75% improvement in the Psoriasis Area and Severity Index (PASI 75). Other measurements included PASI 50, PASI 90, patient's and dermatologist's global assessments, and Dermatology Life Quality Index. RESULTS: In the integrated analyses, statistically significant, dose-dependent improvements in PASI 75 at 12 weeks were observed in patients treated with etanercept 50 mg weekly (33%) and 50 mg twice weekly (49%), compared with the placebo group (3%; P < .05). Significant improvements also were seen in all secondary end points (PASI 50 and PASI 90 responses, patient's and dermatologist's global assessments, and Dermatology Life Quality Index) at 12 weeks. Subgroup analyses of baseline patient characteristics demonstrated that there were no statistically significant treatment-by-covariate interactions. LIMITATIONS: A limitation of these integrated analyses is the relatively short (12-week) time frame. CONCLUSION: The efficacy profile of etanercept in patients with psoriasis was consistent across multiple studies as shown in the integrated analyses of the primary and secondary end points. Etanercept demonstrated rapid, dose-dependent improvements in disease severity and quality of life consistently over all studies.

Etanercept monotherapy in patients with psoriasis: a summary of safety, based on an integrated multistudy database.

BACKGROUND: Etanercept, a tumor necrosis factor antagonist, is an approved treatment in the United States and Europe for plaque psoriasis. OBJECTIVE: To further examine the safety profile of etanercept in patients with chronic, moderate to severe plaque psoriasis. METHODS: Safety data from an integrated database of 1347 patients from 3 randomized, double-blind, placebo-controlled clinical trials were analyzed. Safety end points included incidence rates of adverse events, serious adverse events, infections, serious infections, injection site reactions, and routine laboratory assessments. Pooled safety results from the first 12 weeks of each trial are reported here. RESULTS: Rates of adverse events, serious adverse events, infections, and serious infections in the first 12 weeks of the 3 trials were similar among all active groups as well as each active group, compared with the placebo group. No dose-related toxicities were reported. LIMITATIONS: This report includes a relatively short (12-week) time frame; data from patients exposed to etanercept for longer periods are needed. CONCLUSIONS: Etanercept was generally safe in a large cohort of patients with moderate to severe plaque psoriasis.

Clinical response in psoriasis patients discontinued from and then reinitiated on etanercept therapy.

BACKGROUND: Although continuous therapy with the tumor necrosis factor (TNF) antagonist, etanercept, has been shown to have a favorable benefit to risk profile in the treatment of moderate to severe plaque psoriasis, it is recognized that patients and practioners may wish for intermittent treatment should life circumstances dictate. OBJECTIVE: To evaluate safety and effect maintenance of etanercept retreatment in psoriasis. METHODS: Results of a 24-week, randomized, placebo-controlled, double-blind study were previously reported. Patients who responded at week 24 (improved ?50% in psoriasis area and severity index [PASI]) discontinued etanercept until disease relapse (loss of ?50% of week 24 PASI improvement). Patients were retreated with blinded etanercept at the originally randomized dose: 25 mg or 50 mg twice weekly (BIW) or 25 mg once weekly; original placebo patients received 25 mg BIW for the final 12 weeks of the double-blind period and were retreated with etanercept 25 mg BIW. RESULTS: Psoriasis returned gradually, without untoward events, within, on average, 3 months after etanercept discontinuation. Results after 12 weeks of retreatment were similar to those achieved after the initial 12 weeks. The major limitation of this study is that it examines only one round of discontinuation/retreatment. CONCLUSIONS: Retreatment with etanercept was effective and well tolerated in psoriasis patients.

No evidence for increased risk of cutaneous squamous cell carcinoma in patients with rheumatoid arthritis receiving etanercept for up to 5 years.

OBJECTIVE: To determine the incidence of cutaneous squamous cell carcinoma (SCC) in patients with rheumatoid arthritis receiving etanercept, a tumor necrosis factor antagonist, for up to 5 years. DESIGN: An etanercept clinical trials' database and an etanercept postmarketing surveillance database were retrospectively analyzed for the incidence of SCC. SETTING: Patients enrolled in clinical trials of etanercept were from private and institutional practices. The postmarketing database comprised reports from postmarketing trials and solicited and spontaneous reports. Patients A total of 1442 patients with rheumatoid arthritis with 4257 patient-years of etanercept exposure (median exposure, 3.7 years) are included in the clinical trials' database. More than 125,000 patients with more than 250,000 patient-years of etanercept exposure are included in the etanercept postmarketing database. Interventions Most patients enrolled in clinical trials of etanercept received a dosage of 25 mg of etanercept subcutaneously twice weekly for most of the time they received etanercept therapy. RESULTS: Only 4 cases of SCC were observed in the etanercept clinical trials' database, an incidence that compares favorably with the expected incidences based on general population data from Arizona (13.1) and Minnesota (5.9). Similarly, few cases of SCC (1 per 10,000 patient-years) have been reported during postmarketing surveillance of etanercept therapy. CONCLUSION: In patients with rheumatoid arthritis, etanercept use of up to 5 years does not seem to be associated with an increase in the incidence of cutaneous SCC.

A randomized trial of etanercept as monotherapy for psoriasis.

OBJECTIVE: To determine safety and efficacy of monotherapy with etanercept. DESIGN: Randomized, double-blind, placebo-controlled, multicenter study. SETTING: Outpatient, ambulatory; private practice and university dermatology research centers. PATIENTS: Patients aged at least 18 years, with plaque psoriasis involving 10% or more of body surface area; 148 were screened and 112 were randomly assigned to treatment groups and received study drug. INTERVENTIONS: Patients received placebo or etanercept, 25 mg, subcutaneously twice a week for 24 weeks. Other psoriasis therapies were limited during the study. MAIN OUTCOME MEASURES: Safety measurements included tracking of adverse events and laboratory values. Efficacy was evaluated using the Psoriasis Area and Severity Index (PASI); the primary end point was a 75% improvement in PASI. Other efficacy measurements included patient and physician global assessments and quality-of-life measures. RESULTS: After 12 weeks of treatment, 17 (30%) of the 57 etanercept-treated patients and 1 (2%) of the 55 placebo-treated patients had achieved PASI 75%, and after 24 weeks, 32 (56%) of etanercept-treated patients and 3 (5%) of placebo-treated patients had reached this level (P<.001 for both time points). By 24 weeks, psoriasis was clear or minimal by physician's global assessment in more than 50% of patients who received etanercept. Treatment failure (PASI response <50) occurred in 23% of patients at week 24. All other measures confirmed the efficacy of etanercept. Adverse events were similar among etanercept and placebo groups. CONCLUSION: Etanercept monotherapy provided significant benefit to patients with psoriasis and had a favorable safety profile.

Neurostimulation of the cholinergic anti-inflammatory pathway ameliorates disease in rat collagen-induced arthritis.

INTRODUCTION: The inflammatory reflex is a physiological mechanism through which the nervous system maintains immunologic homeostasis by modulating innate and adaptive immunity. We postulated that the reflex might be harnessed therapeutically to reduce pathological levels of inflammation in rheumatoid arthritis by activating its prototypical efferent arm, termed the cholinergic anti-inflammatory pathway. To explore this, we determined whether electrical neurostimulation of the cholinergic anti-inflammatory pathway reduced disease severity in the collagen-induced arthritis model. METHODS: Rats implanted with vagus nerve cuff electrodes had collagen-induced arthritis induced and were followed for 15 days. Animals underwent active or sham electrical stimulation once daily from day 9 through the conclusion of the study. Joint swelling, histology, and levels of cytokines and bone metabolism mediators were assessed. RESULTS: Compared with sham treatment, active neurostimulation of the cholinergic anti-inflammatory pathway resulted in a 52% reduction in ankle diameter (p = 0.02), a 57% reduction in ankle diameter (area under curve; p = 0.02) and 46% reduction overall histological arthritis score (p = 0.01) with significant improvements in inflammation, pannus formation, cartilage destruction, and bone erosion (p = 0.02), accompanied by numerical reductions in systemic cytokine levels, not reaching statistical significance. Bone erosion improvement was associated with a decrease in serum levels of receptor activator of NF-κB ligand (RANKL) from 132±13 to 6±2 pg/mL (mean±SEM, p = 0.01). CONCLUSIONS: The severity of collagen-induced arthritis is reduced by neurostimulation of the cholinergic anti-inflammatory pathway delivered using an implanted electrical vagus nerve stimulation cuff electrode, and supports the rationale for testing this approach in human inflammatory disorders.

Treatment of chronic inflammatory diseases with implantable medical devices.

Implantable medical devices are finding increasing use in the treatment of diseases traditionally targeted with drugs. It is well established that the cholinergic anti-inflammatory pathway serves as a physiological regulator of inflammatory responses, but stimulation of this pathway therapeutically by electrical stimulation of the vagus nerve can also diminish excessive or dysregulated states of inflammation. Recent data from a wide variety of animal models, as well as evidence of reduced vagal tone in rheumatoid arthritis and other inflammatory diseases, support the rationale for, and feasibility of, developing implantable vagal nerve stimulation devices to treat chronic inflammation in humans.

Pharmacokinetics of subcutaneously administered etanercept in subjects with psoriasis.

AIMS: To present the results of the pharmacokinetic analysis of the concentration-time profiles of etanercept, a soluble receptor tumour necrosis factor (TNF) antagonist, in more than 1300 subjects with psoriasis. METHODS: Pharmacokinetic samples were collected in one phase-2 and two phase-3 placebo-controlled, randomized clinical trials. Study 1 evaluated a 25-mg twice weekly (BIW) etanercept dosing regimen administered by subcutaneous (s.c.) injection for 24 weeks. Study 2 evaluated 25-mg BIW and 50-mg BIW s.c. doses for 12 weeks. Study 3 evaluated 25 mg once weekly (QW), 25 mg BIW and 50 mg BIW s.c. doses for 24 weeks. RESULTS: The mean +/- SD steady-state predose serum concentrations of etanercept for the 25-mg BIW arm at 12 weeks in study 1 were 1590 +/- 885 ng ml(-1). In study 2, mean +/- SD etanercept steady-state concentrations at 12 weeks were 1900 +/- 1110 ng ml(-1) in the 25-mg BIW group and 3830 +/- 1870 ng ml(-1) in the 50-mg BIW group. The mean +/- SD steady-state predose serum concentrations of etanercept at 12 weeks in study 3 were 768 +/- 475 ng ml(-1) for the 25-mg QW regimen, 1990 +/- 1030 ng ml(-1) for the 25-mg BIW regimen and 4020 +/- 2100 ng ml(-1) for the 50-mg BIW regimen. CONCLUSIONS: Pharmacokinetic results were highly consistent across clinical trials. The concentration-time profiles displayed dose proportionality. Etanercept concentrations in subjects with psoriasis are similar to the concentrations in subjects with rheumatoid arthritis.

Population pharmacokinetic modeling of subcutaneously administered etanercept in patients with psoriasis.

The objective of this paper is to present a population PK model which adequately describes the time-concentration profiles of different doses of ctanercept (Enbrel) administered subcutaneously to subjects with moderate-to-severe psoriasis and to simulate the time courses of concentrations following 50 mg once weekly (QW) dosing. Pharmacokinetic (PK) data from three clinical studies with doses 25 mg QW 25 mg twice weekly (BIW) and 50 mg BIW, were used. A one-compartment model with gender, weight and time covariates on the apparent clearance and weight covariate on the apparent volume of distribution was developed. The population mean of the apparent steady state clearance in males was 0.129 l/h. compared to 0.148 l/h in females. The clearance varied with time being lower in the first 2 weeks of the therapy, increasing sharply during weeks 3-4. and converging gradually after that to its steady state level. The population mean of the apparent volume of distribution also varied with time and was 16.11 during week 1, 20.01 during weeks 2-4 and 22.51 after week 4. The population PK model adequately described the observed concentration-time profiles in subjects with psoriasis. Despite a somewhat different covariate set, the parameter estimates of the population PK model for etanercept are very similar between the psoriasis and rheumatoid arthritis populations. The population PK model was used to simulate the pharmacokinetic profiles after a novel 50 mg QW dosing regimen. The simulations show good agreement with the observed data from 84 subjects participating in a fourth study (50 mg QW dose) used as an external validation set. The simulations of the 50 mg QW and the 25 mg BIW dosing regimens show that there is a significant overlap between the profiles yielding similar steady state exposures with both dosing regimens. The latter is an indication that the respective efficacy and safety profiles after those two dosing regimens are likely to be similar.