Variability in Antinuclear Antibody Testing to Assess Patient Eligibility for Clinical Trials of Novel Treatments for Systemic Lupus Erythematosus.

OBJECTIVE: In the development of novel therapies for systemic lupus erythematosus, antinuclear antibody (ANA) positivity represents a criterion for trial eligibility. Since as many as 30% of patients enrolled in trials have been ANA negative, we evaluated the performance characteristics of immunofluorescence assays (IFAs) for ANA determinations for screening. METHODS: This study used 5 commercially available IFAs to assess the ANA status of 181 patients enrolled in a phase II clinical trial for an anti-interleukin-6 antibody. Enrollment included a detailed review of medical records to verify a historical ANA value. IFA results were related to various clinical and serologic features at enrollment. RESULTS: While the frequency of ANA negativity assessed by the central laboratory was 23.8% in a cohort of 181 patients, the evaluated IFA kits demonstrated frequencies of negativity from 0.6 to 27.6%. With 2 IFA kits showing a significant frequency of ANA negativity, positive and negative samples differed in levels of anti-double-stranded DNA, C3, and presence of other ANAs as well as the frequency of high interferon (IFN) expression. CONCLUSION: These findings indicate that, when used for screening, IFAs can vary because of performance characteristics of kits and thus can affect determination of trial eligibility. With kits producing a significant frequency of ANA negativity, ANA status can be associated with other serologic measures as well as the presence of the IFN signature, potentially affecting responsiveness to a trial agent.

Efficacy and safety of an interleukin 6 monoclonal antibody for the treatment of systemic lupus erythematosus: a phase II dose-ranging randomised controlled trial.

OBJECTIVES: This phase II trial evaluated the efficacy and safety of an interleukin (IL) 6 monoclonal antibody for systemic lupus erythematosus (SLE). METHODS: Patients with active disease were randomised to placebo or PF-04236921 10 mg, 50 mg or 200 mg, subcutaneously, every 8 weeks with stable background therapy. SLE Responder Index (SRI-4; primary end point) and British Isles Lupus Assessment Group-based Composite Lupus Assessment (BICLA) were assessed at week 24. Post hoc analysis identified an enriched population based upon planned univariate analyses. RESULTS: 183 patients received treatment (placebo, n=45; 10 mg, n=45; 50 mg, n=47; 200 mg, n=46). The 200 mg dose was discontinued due to safety findings and not included in the primary efficacy analysis. The SRI-4 response rates were not significant for any dose compared with placebo; however, the BICLA response rate was significant for 10 mg (p=0.026). The incidence of severe flares was significantly reduced with 10 mg (n=0) and 50 mg (n=2) combined versus placebo (n=8; p<0.01). In patients with greater baseline disease activity (enriched population), the SRI-4 (p=0.004) and BICLA (p=0.012) response rates were significantly different with 10 mg versus placebo. Four deaths (200 mg, n=3; 10 mg, n=1) occurred. The most frequently reported adverse events included headache, nausea and diarrhoea. CONCLUSIONS: PF-04236921 was not significantly different from placebo for the primary efficacy end point in patients with SLE. Evidence of an effect with 10 mg was seen in a post hoc analysis. Safety was acceptable for doses up to 50 mg as the 200 mg dose was discontinued due to safety findings. TRIAL REGISTRATION NUMBER: NCT01405196; Pre-results.

Two-year Efficacy and Safety of Etanercept in Pediatric Patients with Extended Oligoarthritis, Enthesitis-related Arthritis, or Psoriatic Arthritis.

OBJECTIVE: The main objective was to determine the 2-year clinical benefit and safety of etanercept (ETN) in children with the juvenile idiopathic arthritis (JIA) categories of extended oligoarthritis (eoJIA), enthesitis-related arthritis (ERA), or psoriatic arthritis (PsA). METHODS: CLIPPER was a 96-week, phase IIIb, open-label, multicenter study. Patients with eoJIA, ERA, or PsA received ETN 0.8 mg/kg once weekly (50 mg max) for up to 96 weeks. The proportions of patients reaching the JIA American College of Rheumatology (ACR) 30/50/70/90/100 and inactive disease responses at Week 96 were calculated. Adverse events (AE) were collected throughout the study (intention-to-treat sample). RESULTS: There were 127 patients (eoJIA n = 60, ERA n = 38, PsA n = 29) who received ≥ 1 dose of ETN. The mean disease duration was 31.6 (eoJIA), 23.0 (ERA), and 21.8 (PsA) months. At Week 96, JIA ACR 30/50/70/90/100/inactive disease responses (95% CI) were achieved by 84.3% (76.7, 90.1), 83.5% (75.8, 89.5), 78.7% (70.6, 85.5), 55.1% (46.0, 63.9), 45.7% (36.8, 54.7), and 27.6% (20.0, 36.2) of patients, respectively. The most common AE (no. events, events per 100 patient-yrs) overall were headache (23, 10.7), pyrexia (12, 5.6), and diarrhea (10, 4.6). The most common infections were upper respiratory tract infection (83, 38.6), pharyngitis (50, 23.2), gastroenteritis (22, 10.2), bronchitis (19, 8.8), and rhinitis (17, 7.9). No cases of malignancy, active tuberculosis, demyelinating disorders, or death were reported. CONCLUSION: Over 96 weeks of therapy, ETN demonstrated sustained efficacy at treating the clinical symptoms of all 3 JIA categories, with no major safety issues.

Clinical and MRI responses to etanercept in early non-radiographic axial spondyloarthritis: 48-week results from the EMBARK study.

OBJECTIVE: To evaluate the efficacy and safety of etanercept (ETN) after 48 weeks in patients with early active non-radiographic axial spondyloarthritis (nr-axSpA). METHODS: Patients meeting Assessment of SpondyloArthritis international Society (ASAS) classification criteria for axSpA, but not modified New York radiographic criteria, received double-blind ETN 50 mg/week or placebo (PBO) for 12 weeks, then open-label ETN (ETN/ETN or PBO/ETN). Clinical, health, productivity, MRI and safety outcomes were assessed and the 48-week data are presented here. RESULTS: 208/225 patients (92%) entered the open-label phase at week 12 (ETN, n=102; PBO, n=106). The percentage of patients achieving ASAS40 increased from 33% to 52% between weeks 12 and 48 for ETN/ETN and from 15% to 53% for PBO/ETN (within-group p value <0.001 for both). For ETN/ETN and PBO/ETN, the EuroQol 5 Dimensions utility score improved by 0.14 and 0.08, respectively, between baseline and week 12 and by 0.23 and 0.22 between baseline and week 48. Between weeks 12 and 48, MRI Spondyloarthritis Research Consortium of Canada sacroiliac joint (SIJ) scores decreased by -1.1 for ETN/ETN and by -3.0 for PBO/ETN, p<0.001 for both. Decreases in MRI SIJ inflammation and C-reactive protein correlated with several clinical outcomes at weeks 12 and 48. CONCLUSIONS: Patients with early active nr-axSpA demonstrated improvement from week 12 in clinical, health, productivity and MRI outcomes that was sustained to 48 weeks. TRIAL REGISTRATION NUMBER: NCT01258738.

Pharmacokinetics, efficacy and safety profiles of etanercept monotherapy in Japanese patients with rheumatoid arthritis: review of seven clinical trials.

Abstract Conventional synthetic disease-modifying anti-rheumatic drugs, including methotrexate, may not be tolerated by all patients with rheumatoid arthritis (RA), and limited international data for etanercept (ETN) monotherapy are available. The aim of this review was to summarize the clinical program for ETN monotherapy in Japanese patients with RA, which has included a pharmacokinetic study, clinical trials for registration, long-term studies, and once-weekly dosing studies. Pharmacokinetic results showed that serum concentrations of ETN were linear with dose levels and were similar to other international studies. Across interventional studies, 652 Japanese patients with active RA were treated with ETN. In the registration studies, ETN treatment led to consistent improvement in American College of Rheumatology 20/50/70 scores, European League Against Rheumatism Good Response, Disease Activity Score 28 erythrocyte sedimentation rate remission, and Health Assessment Questionnaire disability index. In the long-term studies, efficacy was maintained for up to 180 weeks. Similar results were seen in the once-weekly studies. Across the studies, more than 870 patient-years of exposure to ETN were recorded. Discontinuations owing to lack of efficacy or adverse events were modest and no new safety signals were recorded. These studies demonstrated that ETN monotherapy is efficacious and well-tolerated in Japanese patients with RA.

Symptomatic efficacy of etanercept and its effects on objective signs of inflammation in early nonradiographic axial spondyloarthritis: a multicenter, randomized, double-blind, placebo-controlled trial.

OBJECTIVE: To assess the efficacy of etanercept in the treatment of early active nonsteroidal antiinflammatory drug (NSAID)-refractory nonradiographic axial spondyloarthritis (SpA). METHODS: The study population consisted of patients who met the Assessment of SpondyloArthritis international Society (ASAS) classification criteria for axial SpA but not the modified New York radiographic criteria for ankylosing spondylitis (as assessed by a radiologist at the central trial site), had a symptom duration of >3 months but <5 years, had a score of ≥4 on the Bath Ankylosing Spondylitis Disease Activity Index, and had been treated unsuccessfully with ≥2 NSAIDs. Patients were randomized to receive etanercept 50 mg/week or placebo and continued background NSAID treatment for 12 weeks (double-blind study); during the subsequent open-label period, all patients received etanercept 50 mg/week. The primary study end point was meeting the ASAS criteria for 40% improvement (ASAS40) at week 12. Magnetic resonance imaging (MRI) of the sacroiliac joints and spine was performed at baseline and week 12. RESULTS: One hundred six patients were randomized to the etanercept group and 109 to the placebo group. Of the 215 patients, the mean ± SD age at baseline was 32.0 ± 7.8 years, 154 (72%) were HLA-B27 positive, and 174 (81%) had MRI-confirmed sacroiliitis. At 12 weeks, the proportion of patients with improvement according to the ASAS40 was significantly higher in the etanercept group than in the placebo group (34 of 105 [32%] versus 17 of 108 [16%]; P = 0.006). Patients who received etanercept exhibited a greater reduction in MRI-based scores for sacroiliac joint inflammation (-46.9% versus -10.9%; P < 0.001) and spinal inflammation (-45.4% versus -33.4%; P = 0.04) compared with placebo-treated patients at week 12. Post hoc analyses suggested a possible association between higher baseline C-reactive protein levels or MRI sacroiliac joint inflammation scores and higher rates of ASAS40 response to etanercept. At week 24, patients in the placebo group who had switched to etanercept at 12 weeks exhibited improvement similar to that observed in patients who had received etanercept for 24 weeks. CONCLUSION: In patients with nonradiographic axial SpA, etanercept treatment was associated with rapid, significant improvement in symptomatic disease activity, function, and systemic and skeletal inflammation over 12 weeks; clinical/functional improvement was sustained over 24 weeks.

Efficacy and safety of open-label etanercept on extended oligoarticular juvenile idiopathic arthritis, enthesitis-related arthritis and psoriatic arthritis: part 1 (week 12) of the CLIPPER study.

OBJECTIVE: To investigate the efficacy and safety of etanercept (ETN) in paediatric subjects with extended oligoarticular juvenile idiopathic arthritis (eoJIA), enthesitis-related arthritis (ERA), or psoriatic arthritis (PsA). METHODS: CLIPPER is an ongoing, Phase 3b, open-label, multicentre study; the 12-week (Part 1) data are reported here. Subjects with eoJIA (2-17 years), ERA (12-17 years), or PsA (12-17 years) received ETN 0.8 mg/kg once weekly (maximum 50 mg). Primary endpoint was the percentage of subjects achieving JIA American College of Rheumatology (ACR) 30 criteria at week 12; secondary outcomes included JIA ACR 50/70/90 and inactive disease. RESULTS: 122/127 (96.1%) subjects completed the study (mean age 11.7 years). JIA ACR 30 (95% CI) was achieved by 88.6% (81.6% to 93.6%) of subjects overall; 89.7% (78.8% to 96.1%) with eoJIA, 83.3% (67.2% to 93.6%) with ERA and 93.1% (77.2% to 99.2%) with PsA. For eoJIA, ERA, or PsA categories, the ORs of ETN vs the historical placebo data were 26.2, 15.1 and 40.7, respectively. Overall JIA ACR 50, 70, 90 and inactive disease were achieved by 81.1, 61.5, 29.8 and 12.1%, respectively. Treatment-emergent adverse events (AEs), infections, and serious AEs, were reported in 45 (35.4%), 58 (45.7%), and 4 (3.1%), subjects, respectively. Serious AEs were one case each of abdominal pain, bronchopneumonia, gastroenteritis and pyelocystitis. One subject reported herpes zoster and another varicella. No differences in safety were observed across the JIA categories. CONCLUSIONS: ETN treatment for 12 weeks was effective and well tolerated in paediatric subjects with eoJIA, ERA and PsA, with no unexpected safety findings.

A phase 3 randomized, double-blind, multicenter comparative study evaluating the effect of etanercept versus methotrexate on radiographic outcomes, disease activity, and safety in Japanese subjects with active rheumatoid arthritis.

OBJECTIVES: The aim of this phase 3, double-blind study was to compare the radiographic and clinical effects of etanercept (ETN) versus methotrexate (MTX) over 52 weeks in Japanese subjects with active rheumatoid arthritis. METHODS: The study population comprised 550 subjects with inadequate response to ≥1 disease-modifying anti-rheumatic drugs who were randomized to treatment groups of ETN 25 mg twice weekly (BIW; n = 182), ETN 10 mg BIW (n = 192), or MTX (≤8.0 mg/week; n = 176). RESULTS: Of the 550 subjects initially enrolled in the three treatment groups, 21.6% discontinued the study; a significantly higher proportion of those who withdrew from the study due to lack of efficacy were in the MTX (21.6%) group compared with the ETN 25 mg (3.3%) and ETN 10 mg (6.8%) groups (P < 0.001). Mean change from baseline in the modified total Sharp score at week 52 (primary endpoint) was significantly lower in the ETN 25 mg [3.33; standard error (SE), 0.73] and ETN 10 mg (5.19; SE 0.93) groups than in the MTX group (9.82; SE 1.16; P < 0.0001 vs. either ETN group). Compared with subjects receiving MTX, significantly higher percentages of subjects treated with ETN 25 and 10 mg achieved American College of Rheumatology (ACR) ACR20 and ACR50 response rates at all time points (P < 0.01). ETN was well-tolerated, with no unexpected safety findings. CONCLUSIONS: ETN 25 mg BIW and ETN 10 mg BIW slowed radiographic progression and improved clinical outcomes more effectively than MTX in this Japanese population.

Safety and efficacy of long-term etanercept in the treatment of methotrexate-refractory polyarticular-course juvenile idiopathic arthritis in Japan.

OBJECTIVES: Previous short-term trials found etanercept (0.2 or 0.4 mg/kg) to be effective and well tolerated in Japanese children with juvenile idiopathic arthritis (JIA) who were intolerant/resistant to methotrexate. The aim of this study was to evaluate the long-term safety and efficacy of etanercept in Japanese children with JIA. METHODS: Patients (4-19 years) who received etanercept in one of three short-term studies continued onto this long-term open-label study. RESULTS: Of the 32 patients enrolled, 18 (56.3%) completed 192 weeks of the study and 14 (43.8%) were discontinued; 7 (21.9%) for patient refusal, 2 (6.3%) for adverse events (AEs), and 5 (15.6%) for lack of efficacy. All patients reported AEs; 31 (96.9%) reported infections and 6 (18.8%) reported serious AEs. Main efficacy assessments included change from baseline in the American College of Rheumatology Pediatric core components, including mean improvements from baseline in the physician global assessment (90.7%), patient/guardian global assessments (54.1%), Childhood Health Assessment Questionnaire (84.6%), and median improvements in C-reactive protein levels (92.7%). No unexpected safety results were reported, and early efficacy responses were sustained in the long term. CONCLUSIONS: This study provides further evidence that etanercept is an effective therapeutic option for Japanese children with polyarticular-course JIA.

Etanercept in the treatment of disease-modifying anti-rheumatic drug (DMARD)-refractory polyarticular course juvenile idiopathic arthritis: experience from Japanese clinical trials.

Efficacy, safety, and pharmacokinetics results from 4 studies-3 open-label (OL) and 1 randomized double-blind (DB)-have provided data for approval of etanercept for treatment of disease-modifying anti-rheumatic drug (DMARD)-refractory juvenile idiopathic arthritis (JIA) in Japan. Results from the 3 shorter-term (2 OL and 1 DB) studies are reported here. Subjects (4-17 years) enrolled in the OL studies had active JIA, i.e. ≥5 swollen joints and ≥3 joints with limitation of motion and pain or tenderness. Subjects enrolled in the primary OL study received etanercept 0.4 mg/kg subcutaneously twice weekly; in the lower-dose OL study subjects received etanercept 0.2 mg/kg. Subjects in the primary OL study who completed ≥48 weeks could continue into a 12-week DB dose-down extension study in which subjects received etanercept 0.4 or 0.2 mg/kg twice weekly. The primary endpoint in all 3 studies, i.e. 30% improvement in the American College of Rheumatology criteria for JIA (ACR Pedi 30) at 12 weeks, was achieved by ≥80% of subjects by week 2 and sustained to week 12. Common adverse events reported were injection site reactions, nasopharyngitis, and gastroenteritis. These results provide further evidence that etanercept is effective therapy for DMARD-refractory polyarticular JIA patients.

Clinical trial safety and mortality analyses in patients receiving etanercept across approved indications.

OBJECTIVES: Assessment of associations between etanercept treatment and rare adverse events has been limited by the size of clinical trial populations. The authors examined the collective safety of etanercept in clinical trials across approved indications. PATIENTS AND METHODS: Forty-nine U.S. and non-U.S. trials of etanercept, involving up to 13,977 patients for approved indications, with final trial reports as of May 2006, were selected from the Amgen Inc. clinical trials database. Exposure-adjusted rates of serious infections, opportunistic infections, malignancies, and deaths were reported by trial, indication, and dosage. RESULTS: Rates of serious infections were generally similar between etanercept and controls. Overall rates of opportunistic infections and tuberculosis were low. The standardized incidence ratio (SIR) (95% CI) for malignancy was 1.00 (0.83-1.19) for all etanercept patients across all indications. The SIR for lymphoma for patients with rheumatoid arthritis was 3.45 (1.83-5.89); all other indications reported SIRs similar to those observed in the general population. The SIRs for cutaneous squamous cell carcinoma in patients with psoriasis relative to the general population with high or low sun exposure were 2.09 (1.27-3.22) and 4.96 (3.03-7.66), respectively. SIRs were less than 1.0 for all other indications regardless of sun exposure. Rates of melanoma and basal cell carcinoma were not significantly different from those in the general population. There was no increase in mortality associated with etanercept use relative to control populations. CONCLUSION: These data support the overall tolerability of etanercept across approved indications.

Once-weekly administration of etanercept 50 mg improves patient-reported outcomes in patients with moderate-to-severe plaque psoriasis.

OBJECTIVE: To assess baseline patient-reported outcomes (PROs) and PRO improvement in patients with psoriasis administered etanercept 50 mg once weekly (QW). METHODS: Adult patients with moderate-to-severe plaque psoriasis participated in a 12-week, double-blind, controlled trial in which they received etanercept 50 mg QW (n = 96) or placebo QW (n = 46), followed by a 12-week, open-label extension in which they received etanercept 50 mg QW (etanercept-etanercept, n = 90; placebo-etanercept, n = 36). Patients completed the Dermatology Life Quality Index (DLQI), EuroQoL-5D (EQ-5D) and Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) at baseline and subsequent study visits. RESULTS: At baseline, DLQI and EQ-5D scores indicated significant quality of life (QoL) impairment, and FACIT-F scores suggested more fatigue than in the general population. At week 12, etanercept 50 mg QW provided statistically significantly (p < 0.05) and clinically meaningfully greater improvement in DLQI and EQ-5D utility scores than placebo, but not in FACIT-F scores. After 24 weeks of etanercept, the mean DLQI suggested psoriasis had a small effect on QoL, while EQ-5D and FACIT-F scores were comparable to population norms. CONCLUSIONS: Patients with moderate-to-severe psoriasis entered this trial with serious PRO impairment. At week 12, etanercept 50 mg QW provided significant QoL improvements compared with placebo. After 24 weeks of etanercept, the patients' serious PRO impairment had largely abated.

Etanercept in the longterm treatment of patients with ankylosing spondylitis.

OBJECTIVE: To evaluate the 2-year efficacy and safety of etanercept in patients with ankylosing spondylitis (AS). METHODS: A 96-week open-label extension study, which followed a 12-week double-blind placebo-controlled trial, was designed to provide longterm efficacy and safety data, including radiographic outcomes, for patients treated with etanercept 25 mg twice weekly (NCT00421980). In all, 81 patients were enrolled (96% of the participants from the double-blind study). Key efficacy measures included improvement using the Assessment in Ankylosing Spondylitis 20% (ASAS20) criteria, the Bath Ankylosing Spondylitis Functional Index (BASFI), and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). Radiographic progression was evaluated using the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) method. Paired t tests were used to test within-group changes from baseline. RESULTS: The percentage of responders, by ASAS20 criteria, remained relatively constant in patients who received etanercept during the 12-week double-blind study (60% at Week 0 and 83% at Week 96 of the open-label extension); more patients from the placebo group became responders after being switched to etanercept (23% and 74%, respectively). A similar trend was also observed using the ASAS40 and ASAS5/6 criteria, the BASFI, and the BASDAI. Most patients had no change from baseline in mSASSS values. Etanercept was well tolerated; the most frequent adverse events were injection site reactions (n=30; 37.0%) and headache (n=18; 22.2%), and the most frequent infections were upper respiratory tract infections (n=43; 53.1%) and flu syndrome (n=22; 27.2%). CONCLUSION: For 2 years, etanercept was clinically effective and well tolerated, with no unexpected safety findings.

Comparison of etanercept and methotrexate, alone and combined, in the treatment of rheumatoid arthritis: two-year clinical and radiographic results from the TEMPO study, a double-blind, randomized trial.

OBJECTIVE: To evaluate the efficacy, including radiographic changes, and safety of etanercept and methotrexate (MTX), used in combination and alone, in patients with rheumatoid arthritis (RA) in whom previous treatment with a disease-modifying antirheumatic drug other than MTX had failed. METHODS: Patients with RA were treated with etanercept (25 mg subcutaneously twice weekly), oral MTX (up to 20 mg weekly), or combination therapy with etanercept plus MTX through a second year, in a double-blinded manner. Clinical response was assessed using American College of Rheumatology (ACR) criteria and the Disease Activity Score (DAS), in a modified intent-to-treat analysis with the last observation carried forward (LOCF) and in a population of completers. Radiographs of the hands, wrists, and forefeet were scored for erosions and joint space narrowing at annual intervals. RESULTS: A total of 503 of 686 patients continued into year 2 of the study. During the 2 years, significantly fewer patients receiving combination therapy withdrew from the study (29% of the combination therapy group, 39% of the etanercept group, and 48% of the MTX group). Both the LOCF and the completer analyses yielded similar results. The ACR 20% improvement (ACR20), ACR50, and ACR70 responses and the remission rates (based on a DAS of <1.6) were significantly higher with combination therapy than with either monotherapy (P<0.01). Similarly, improvement in disability (based on the Health Assessment Questionnaire) was greater with combination therapy (P<0.01). The combination therapy group showed significantly less radiographic progression than did either group receiving monotherapy (P<0.05); moreover, radiographic progression was significantly lower in the etanercept group compared with the MTX group (P<0.05). For the second consecutive year, overall disease progression in the combination therapy group was negative, with the 95% confidence interval less than zero. Adverse events were similar in the 3 treatment groups. CONCLUSION: Etanercept in combination with MTX reduced disease activity, slowed radiographic progression, and improved function more effectively than did either monotherapy over a 2-year period. No increase in toxicity was associated with combination treatment with etanercept plus MTX.

Unaltered etanercept pharmacokinetics with concurrent methotrexate in patients with rheumatoid arthritis.

The purpose of this study was to evaluate the potential impact of concurrent weekly oral methotrexate administration on the pharmacokinetics of etanercept in patients with rheumatoid arthritis (RA) in a phase 3B trial. As part of a double-blind randomized trial of 682 patients with rheumatoid arthritis who received etanercept (25 mg subcutaneously twice weekly), methotrexate (weekly oral dose, median weekly dose: 20 mg), or etanercept (25 mg subcutaneously twice weekly) plus methotrexate (weekly oral dose, median weekly dose: 20 mg), serum etanercept concentrations were measured in a subset of patients. Serum samples for 98 randomly selected patients (48 receiving etanercept-alone treatment, 50 receiving etanercept plus methotrexate combination treatment) were analyzed to assess the pharmacokinetics of etanercept. A single blood sample was drawn from each patient at baseline and at the week 24 visit. Given the variable sampling time for patients in both groups, a population pharmacokinetic analysis using NONMEM was conducted for etanercept. A final covariate population pharmacokinetic model was constructed based on previously obtained etanercept data from both healthy subjects (n = 53) and patients with RA (n = 212) in 10 prior clinical trials. The predictive performance of the final model was assessed by both bootstrap and data-splitting validation approaches. The final model was then used to estimate Bayesian pharmacokinetic parameters for the patients in both treatments in the current trial. The potential effect of the concurrent administration of methotrexate on the pharmacokinetics of etanercept was examined by comparing the clearance values between 2 treatments using statistical criteria. A population 2-compartment model with first-order elimination from the central compartment and with either zero-order (intravenous administration) or first-order (subcutaneous administration) input was selected based on the data from the prior 10 etanercept clinical studies. The following pharmacokinetic parameters (typical value +/- standard error) were estimated: clearance (CL: 0.072 +/- 0.005 L/h), volume of distribution in the central compartment (V(c): 5.97 +/- 0.45 L), volume of distribution in the peripheral compartment (V(p): 2.05 +/- 0.32 L), intercompartment clearance (Q: 0.0645 +/- 0.0093 L/h), first-order absorption rate constant (k(a): 0.0282 +/- 0.0039 1/h), and absolute bioavailability for subcutaneous administration (F: 0.626 +/- 0.056). Interindividual variability of the pharmacokinetic parameters was quantified for CL (25.1%), V(c) (41.7%), k(a) (53.1%), and F (24.2%). Residual variability consisted of combined additive (11.4 ng/mL) and proportional error (49.9%). Both age (< 17 years) and body weight (< 60 kg) were found to be important covariates on CL. The results of both validation tests indicated the adequate predictive performance of the population model. Based on the bioequivalence criteria, the Bayesian-estimated clearance for patients receiving etanercept alone (mean: 0.070 L/h) was comparable to that for patients receiving a combination of etanercept and methotrexate (mean = 0.066 L/h). The pharmacokinetics of etanercept were not altered by the concurrent administration of methotrexate in patients with rheumatoid arthritis. Thus, no etanercept dose adjustment is needed for patients taking concurrent methotrexate.

Therapeutic effect of the combination of etanercept and methotrexate compared with each treatment alone in patients with rheumatoid arthritis: double-blind randomised controlled trial.

BACKGROUND: Etanercept and methotrexate are effective in the treatment of rheumatoid arthritis but no data exist on concurrent initiation or use of the combination compared with either drug alone. We aimed to assess combination treatment with etanercept and methotrexate versus the monotherapies in patients with rheumatoid arthritis. METHODS: In a double-blind, randomised, clinical efficacy, safety, and radiographic study, 686 patients with active rheumatoid arthritis were randomly allocated to treatment with etanercept 25 mg (subcutaneously twice a week), oral methotrexate (up to 20 mg every week), or the combination. Clinical response was assessed by criteria of the American College of Rheumatology (ACR). The primary efficacy endpoint was the numeric index of the ACR response (ACR-N) area under the curve (AUC) over the first 24 weeks. The primary radiographic endpoint was change from baseline to week 52 in total joint damage and was assessed with the modified Sharp score. Analysis was by intention to treat. FINDINGS: Four patients did not receive any drug; thus 682 were studied. ACR-N AUC at 24 weeks was greater for the combination group compared with etanercept alone and methotrexate alone (18.3%-years [95% CI 17.1-19.6] vs 14.7%-years [13.5-16.0], p<0.0001, and 12.2%-years [11.0-13.4], p<0.0001; respectively). The mean difference in ACR-N AUC between combination and methotrexate alone was 6.1 (95% CI 4.5-7.8, p<0.0001) and between etanercept and methotrexate was 2.5 (0.8-4.2, p=0.0034). The combination was more efficacious than methotrexate or etanercept alone in retardation of joint damage (mean total Sharp score -0.54 [95% CI -1.00 to -0.07] vs 2.80 [1.08 to 4.51], p<0.0001, and 0.52 [-0.10 to 1.15], p=0.0006; respectively). The mean difference in total Sharp score between combination and methotrexate alone was -3.34 (95% CI -4.86 to -1.81, p<0.0001) and between etanercept and methotrexate was -27 (-3.81 to -0.74, p=0.0469). The number of patients reporting infections or adverse events was similar in all groups. INTERPRETATION: The combination of etanercept and methotrexate was significantly better in reduction of disease activity, improvement of functional disability, and retardation of radiographic progression compared with methotrexate or etanercept alone. These findings bring us closer to achievement of remission and repair of structural damage in rheumatoid arthritis.