N-terminus of Etanercept is Proteolytically Processed by Dipeptidyl Peptidase-4.

PURPOSE: Biologics are structurally heterogeneous and can undergo biotransformation in the body. Etanercept (ETN) is a fusion protein composed of a soluble tumor necrosis factor (TNF) receptor and the Fc portion of human immunoglobulin G1. The N-terminus of ETN has a putative sequence cleaved by dipeptidyl peptidase-4 (DPP-4). The purpose of this study was to investigate the biotransformation of ETN in humans and mice and evaluate its effects on functional properties. METHODS: An analytical method using liquid chromatography-mass spectrometry (LC-MS/MS) was established. The N-terminal heterogeneity of ETN was assessed in the serum of patients with rheumatoid arthritis or mice receiving ETN. The in vitro N-terminal truncation was explored using recombinant DPP-4. The binding affinity to TNF-α or TNF-ß was investigated using an in-house enzyme-linked immunosorbent assay. RESULTS: In the formulations, about 90% of ETN had an intact N-terminus, while the N-terminal truncated form was most abundant in the serum of the patients with rheumatoid arthritis and mice. Recombinant human DPP-4 cleaved two amino acids from the N-terminus of ETN in vitro. Sitagliptin, a DPP-4 inhibitor, inhibited N-terminal truncation both in vivo and in vitro. However, N-terminal truncation did not affect the binding ability to TNF-α or TNF-ß and the pharmacokinetics of ETN. ETN biosimilars exhibited similar characteristics to the reference product in vivo and in vitro. CONCLUSIONS: ETN undergoes N-terminal truncation in the body, and DPP-4 cleaves exogenous ETN via N-terminal proteolysis. The application of an MS-based assay will detect novel biotransformation of therapeutic proteins.

Biologic TNF-α inhibitors reduce microgliosis, neuronal loss, and tau phosphorylation in a transgenic mouse model of tauopathy.

BACKGROUND: Tumor necrosis factor-α (TNF-α) plays a central role in Alzheimer's disease (AD) pathology, making biologic TNF-α inhibitors (TNFIs), including etanercept, viable therapeutics for AD. The protective effects of biologic TNFIs on AD hallmark pathology (Aß deposition and tau pathology) have been demonstrated. However, the effects of biologic TNFIs on Aß-independent tau pathology have not been reported. Existing biologic TNFIs do not cross the blood-brain barrier (BBB), therefore we engineered a BBB-penetrating biologic TNFI by fusing the extracellular domain of the type-II human TNF-α receptor (TNFR) to a transferrin receptor antibody (TfRMAb) that ferries the TNFR into the brain via receptor-mediated transcytosis. The present study aimed to investigate the effects of TfRMAb-TNFR (BBB-penetrating TNFI) and etanercept (non-BBB-penetrating TNFI) in the PS19 transgenic mouse model of tauopathy. METHODS: Six-month-old male and female PS19 mice were injected intraperitoneally with saline (n = 12), TfRMAb-TNFR (1.75 mg/kg, n = 10) or etanercept (0.875 mg/kg, equimolar dose of TNFR, n = 10) 3 days/week for 8 weeks. Age-matched littermate wild-type mice served as additional controls. Blood was collected at baseline and 8 weeks for a complete blood count. Locomotion hyperactivity was assessed by the open-field paradigm. Brains were examined for phosphorylated tau lesions (Ser202, Thr205), microgliosis, and neuronal health. The plasma pharmacokinetics were evaluated following a single intraperitoneal injection of 0.875 mg/kg etanercept or 1.75 mg/kg TfRMAb-TNFR or 1.75 mg/kg chronic TfRMAb-TNFR dosing for 4 weeks. RESULTS: Etanercept significantly reduced phosphorylated tau and microgliosis in the PS19 mouse brains of both sexes, while TfRMAb-TNFR significantly reduced these parameters in the female PS19 mice. Both TfRMAb-TNFR and etanercept treatment improved neuronal health by significantly increasing PSD95 expression and attenuating hippocampal neuron loss in the PS19 mice. The locomotion hyperactivity in the male PS19 mice was suppressed by chronic etanercept treatment. Equimolar dosing resulted in eightfold lower plasma exposure of the TfRMAb-TNFR compared with etanercept. The hematological profiles remained largely stable following chronic biologic TNFI dosing except for a significant increase in platelets with etanercept. CONCLUSION: Both TfRMAb-TNFR (BBB-penetrating) and non-BBB-penetrating (etanercept) biologic TNFIs showed therapeutic effects in the PS19 mouse model of tauopathy.

Lymphatic Distribution of Etanercept Following Intravenous and Subcutaneous Delivery to Rats.

PURPOSE: The purpose of this work was to investigate the role of the lymphatic system in the pharmacokinetics of etanercept, a fusion protein. METHODS: Etanercept 1 mg/kg was administered intravenously (IV) and subcutaneously (SC) to thoracic lymph duct-cannulated and sham-operated control rats. Blood and lymph samples were obtained for up to 6 days. RESULTS: Model-based SC bioavailability of etanercept was 65.2% in the control group. In lymph-cannulated rats, etanercept concentration in the lymph was consistently lower than in serum following IV dosing; and the concentration in the lymph was significantly higher than in serum after SC injection. The absorption occurred predominantly through the lymphatic pathway (82.7%), and only 17.3% by direct uptake into the central compartment (blood pathway). Lymphatic cannulation reduced the area under the serum concentration-time curve by 28% in IV group and by 91% in SC group. A mechanistic pharmacokinetic model that combined dual absorption pathways with redistribution of the systemically available protein drug into lymph was developed. The model successfully captured serum and lymph data in all groups simultaneously, and all parameters were estimated with sufficient precision. CONCLUSIONS: Lymphatic system was shown to play an essential role in systemic disposition and SC absorption of etanercept.

Prevalence of switching from two anti-TNF biosimilars back to biologic reference products in Germany
.

AIMS: Biosimilars are becoming more and more important for the treatment of many diseases. However, it is not understood how they are tolerated. Our aim was to analyze the behavior of switching from two anti-TNF biosimilars back to biologic reference products in German patients. MATERIALS AND METHODS: Patients switching from etanercept reference to an etanercept biosimilar between February 2016 and December 2017 and those switching from the infliximab reference product to an infliximab biosimilar between February 2015 and December 2017 were included in the study (index date). The main outcome of this study, the rate of switching from these two biosimilars back to reference products, was analyzed using Kaplan-Meier curves. A multivariate Cox regression model was used to predict the switch-back behavior. RESULTS: A total of 2,956 patients were included in this study. After 3 months, 14.7% and, after 12 months, 30.2% of them were switched back from a biosimilar to the reference product. Sex, age, physician specialty, and co-therapy were not significantly associated with this switch. CONCLUSION: Almost one third of the patients treated with one of two biosimilar drugs after previous biologic therapy are switched back to reference products in Germany.

Phase III, multicentre, double-blind, randomised, parallel-group study to evaluate the similarities between LBEC0101 and etanercept reference product in terms of efficacy and safety in patients with active rheumatoid arthritis inadequately responding to methotrexate.

OBJECTIVE: To evaluate the similarities between LBEC0101 (etanercept biosimilar) and the etanercept reference product (ETN-RP) in terms of efficacy and safety, including immunogenicity, in patients with active rheumatoid arthritis despite methotrexate treatment. METHODS: This phase III, multicentre, randomised, double-blind, parallel-group, 54-week study was conducted in Japan and Korea. The primary efficacy endpoint was the change from baseline in the disease activity score in 28 joints based on erythrocyte sedimentation rate (DAS28-ESR) at week 24. American College of Rheumatology 20% (ACR20) response rate, adverse events (AEs), pharmacokinetics and development of antidrug antibodies (ADAs) were also evaluated. RESULTS: In total, 374 patients were randomised to LBEC0101 (n=187) or ETN-RP (n=187). The least squares mean changes from baseline in DAS28-ESR at week 24 in the per-protocol set were -3.01 (95% CI -3.198 to -2.820) in the LBEC0101 group and -2.86 (95% CI -3.051 to -2.667) in the ETN-RP group. The estimated between-group difference was -0.15 and its 95% CI was -0.377 to 0.078, which was within the prespecified equivalence margin of -0.6 to 0.6. ACR20 response rates at week 24 were similar between the groups (LBEC0101 93.3% vs ETN-RP 86.7%). The incidence of AEs up to week 54 was comparable between the groups (LBEC0101 92.0% vs ETN-RP 92.5%), although fewer patients in the LBEC0101 group (1.6%) than the ETN-RP group (9.6%) developed ADAs. CONCLUSION: The clinical efficacy of LBEC0101 was equivalent to that of ETN-RP. LBEC0101 was well tolerated and had a comparable safety profile to ETN-RP. TRIAL REGISTRATION NUMBER: NCT02357069.

TNF-α level affects etanercept clearance: TNF-α concentration as a new correction factor of allometric scaling to predict individual etanercept clearances in patients with ankylosing spondylitis.

Etanercept (ETN) is a widely used anti-tumour necrosis factor-α (TNF-α) agent, which relieves the symptoms of ankylosing spondylitis (AS) by binding to TNF-α to inhibit its inflammation effects. In this study, the effect of TNF-α level on ETN clearance (CL) was investigated, and the TNF-α concentration was initially set as a correction factor for allometric scaling to improve the predictions of individual ETN CLs. Individual ETN CLs and TNF-α concentrations in healthy volunteers and patients with AS were determined by performing ETN pharmacokinetic studies in the two cohorts. Accordingly, individual ETN CLs in both healthy volunteers and patients with AS were predicted from data of two animal species using different methods, including simple allometric scaling, scaling with a correction factor of maximum life span potential or brain weight, and scaling with a correction factor of the TNF-α concentration. The accuracies of such predictions were evaluated by the percentage errors. Consequently, increased TNF-α concentration was shown to improve ETN CL, by comparing both ETN CLs and TNF-α concentrations between healthy volunteers and patients with AS. More importantly, better predictions of individual ETN CLs were achieved in patients with AS using allometric scaling with TNF-α concentration as the correction factor. In conclusion, in vivo levels of TNF-α can affect ETN CL, and allometric scaling corrected with the TNF-α concentration can be used to estimate the individual CLs of anti-TNF-α monoclonal antibodies based on preclinical data.

A phase III, multicentre, randomised, double-blind, active-controlled, parallel-group trial comparing safety and efficacy of HD203, with innovator etanercept, in combination with methotrexate, in patients with rheumatoid arthritis: the HERA study.

OBJECTIVES: To evaluate equivalence in efficacy for rheumatoid arthritis (RA) and compare the safety of the biosimilar HD203 with innovator etanercept (ETN) plus methotrexate (MTX) (ClinicalTrials.gov NCT01270997). METHODS: Patients with active RA received 25 mg HD203 or ETN subcutaneously twice-weekly with MTX for 48 weeks in a phase III, multicentre, randomised, double-blind, parallel-group design. The primary end point was the proportion of patients achieving the American College of Rheumatology 20% response (ACR20) at week 24 for per-protocol study completer set (PPS). Secondary end points included ACR response criteria, ACRn, European League against Rheumatism (EULAR) response, change in Disease Activity Score 28 (DAS28), patient-reported outcomes, safety and immunogenicity. RESULTS: Of the 294 randomised patients (HD203, n=147; ETN, n=147), 233 comprised the 24-week PPS (n=115 and 118, respectively). ACR20 at week 24 was achieved by 83.48% and 81.36% of PPS patients, respectively, demonstrating equivalent efficacy within predefined margins of ±20% (treatment difference 2.12%, 95% CI -7.65% to 11.89%). Outcomes for secondary end points were consistent with the primary efficacy findings. Groups were comparable for overall incidences of treatment-emergent (all-causality) adverse events (AEs) (HD203 113 (76.9%) vs ETN 114 (78.1%) (p=0.804)), adverse drug reactions, serious AEs and discontinuations due to AEs. Few patients (HD203, n=8; ETN, n=3) tested positive for anti-drug antibodies. CONCLUSION: The study met the primary objective of demonstrating equivalent efficacy of HD203 and ETN. HD203 was well tolerated, with safety comparable with ETN in this population of patients with RA. TRIAL REGISTRATION NUMBER: NCT01270997; Results.

A phase III randomised, double-blind, parallel-group study comparing SB4 with etanercept reference product in patients with active rheumatoid arthritis despite methotrexate therapy.

OBJECTIVES: To compare the efficacy and safety of SB4 (an etanercept biosimilar) with reference product etanercept (ETN) in patients with moderate to severe rheumatoid arthritis (RA) despite methotrexate (MTX) therapy. METHODS: This is a phase III, randomised, double-blind, parallel-group, multicentre study with a 24-week primary endpoint. Patients with moderate to severe RA despite MTX treatment were randomised to receive weekly dose of 50 mg of subcutaneous SB4 or ETN. The primary endpoint was the American College of Rheumatology 20% (ACR20) response at week 24. Other efficacy endpoints as well as safety, immunogenicity and pharmacokinetic parameters were also measured. RESULTS: 596 patients were randomised to either SB4 (N=299) or ETN (N=297). The ACR20 response rate at week 24 in the per-protocol set was 78.1% for SB4 and 80.3% for ETN. The 95% CI of the adjusted treatment difference was -9.41% to 4.98%, which is completely contained within the predefined equivalence margin of -15% to 15%, indicating therapeutic equivalence between SB4 and ETN. Other efficacy endpoints and pharmacokinetic endpoints were comparable. The incidence of treatment-emergent adverse events was comparable (55.2% vs 58.2%), and the incidence of antidrug antibody development up to week 24 was lower in SB4 compared with ETN (0.7% vs 13.1%). CONCLUSIONS: SB4 was shown to be equivalent with ETN in terms of efficacy at week 24. SB4 was well tolerated with a lower immunogenicity profile. The safety profile of SB4 was comparable with that of ETN. TRIAL REGISTRATION NUMBERS: NCT01895309, EudraCT 2012-005026-30.

The EGALITY study: a confirmatory, randomized, double-blind study comparing the efficacy, safety and immunogenicity of GP2015, a proposed etanercept biosimilar, vs. the originator product in patients with moderate-to-severe chronic plaque-type psoriasis.

BACKGROUND: GP2015 is a proposed etanercept biosimilar. OBJECTIVES: To demonstrate equivalent efficacy, and comparable safety and immunogenicity of GP2015 and the etanercept originator (ETN, Enbrel® ) in patients with moderate-to-severe chronic plaque-type psoriasis. METHODS: In total, 531 eligible patients were randomized 1 : 1 to self-administer GP2015 or ETN twice weekly subcutaneously. Patients with ≥ 50% improvement in Psoriasis Area and Severity Index (PASI 50) at week 12 were rerandomized to continue the same treatment on a once-weekly dosing schedule or to undergo a sequence of three treatment switches between GP2015 and ETN until week 30. Thereafter, patients continued treatment with the product they had been assigned to last, up to week 52. RESULTS: The difference in PASI 75 (75% improvement from baseline PASI score) response rates at week 12 between GP2015 and ETN (primary end point) was -2·3%. The 95% confidence interval (-9·85 to 5·30) was well contained within the prespecified margin range of -18 to 18. The incidence of treatment-emergent adverse events up to week 52 was comparable between continued GP2015 (59·8%) and ETN (57·3%); switching treatments revealed comparable safety profiles. Antidrug antibodies, all non-neutralizing, were limited to five patients on ETN during treatment period 1, and one patient in the switched ETN group, who had been treated with GP2015 for 12 weeks at the time of the finding. CONCLUSIONS: The EGALITY study demonstrated equivalent efficacy and comparable safety and immunogenicity of GP2015 and ETN. The study results provide the final clinical confirmation of biosimilarity and contribute to the totality of the evidence proposing that GP2015 is an etanercept biosimilar.

GP2015, a proposed etanercept biosimilar: Pharmacokinetic similarity to its reference product and comparison of its autoinjector device with prefilled syringes.

AIMS: To assess pharmacokinetics (PK) and safety of GP2015, a proposed etanercept biosimilar, in two studies: comparison with etanercept originator (ETN, bioequivalence study) and comparison of GP2015 administered via an autoinjector (AI) or prefilled syringes (PFS, delivery study). METHODS: Both studies were randomized, two-sequence, two-period, crossover studies conducted in healthy male subjects. In the bioequivalence study, subjects were randomized to receive a single 50 mg subcutaneous (s.c.) injection of GP2015 or ETN. In the delivery study, subjects were randomized to receive a single 50 mg s.c. injection of GP2015 via AI or PFS. Following a wash-out period of 35 days, subjects in the bioequivalence study received single 50 mg s.c. injection of GP2015 or ETN, and subjects in the delivery study received single 50 mg s.c. injection of GP2015 via AI or PFS. RESULTS: The geometric mean ratios (90% confidence interval) of GP2015/ETN for Cmax (1.11 [1.05-1.17]), AUC0-tlast (0.98 [0.94-1.02]) and AUC0-inf (0.96 [0.93-1.00]) were within the predefined bioequivalence range of 0.80-1.25. The geometric mean ratios (90% confidence interval) of AI/PFS for Cmax (1.01 [0.94-1.08]), AUC0-tlast (1.01 [0.95-1.07]) and AUC0-inf (1.01 [0.96-1.07]) were also within the range 0.80-1.25. No new safety issues were reported. Three subjects had low titres of non-neutralising anti-drug antibodies during a follow-up visit in the bioequivalence study. CONCLUSIONS: The PK of GP2015 was similar to ETN, demonstrating bioequivalence. The safety profile of GP2015 was consistent with previous reports for ETN. The GP2015 AI provided equivalent dosing and tolerability to the GP2015 PFS.

Determination of adalimumab and etanercept trough levels and drug antibodies in long-term psoriasis treatment: a single-centre cohort study.

BACKGROUND: An algorithm based on measurement of a serum tumour necrosis factor antagonists (anti-TNF) and antidrug antibodies (ADA) has been proposed previously to guide dose escalation or therapy switching in the early (i.e. the first months of) treatment of psoriasis by anti-TNF. In long-term treatment of responding patients with psoriasis, it is usual to empirically reduce standard doses of anti-TNF to reduce exposure while maintaining clinical response. The relationship between serum anti-TNF, ADA levels and clinical efficacy in long-term treated patients with psoriasis has not yet been determined, so the potential role of these parameters in guiding dose escalation in this scenario is unknown. AIMS: To evaluate the relationship between drug/ADA levels and clinical efficacy in a group of patients with psoriasis undergoing long-term treatment with adalimumab or etanercept. METHODS: This was a single-centre, prospective, cohort study of patients with psoriasis receiving adalimumab or etanercept for a minimum of 48 weeks. All patients were started on the standard dose, but some adalimumab users had a reduced frequency of administration. Clinical efficacy was measured using the Psoriasis Area and Severity Index. Serum concentrations were measured by ELISA. Clinical assessment and blood sample collection were carried out simultaneously within 24 h before the next drug administration. RESULTS: In total, 21 patients were enrolled (67 simultaneous clinical and serum determinations: 38 receiving adalimumab, 29 receiving etanercept). We did not find any association between serum anti-TNF levels and clinical response. None of the patients developed ADA. CONCLUSIONS: ADA and anti-TNF levels are not related to clinical effectiveness in patients with psoriasis undergoing long-term treatment with adalimumab or etanercept.

A randomized phase l pharmacokinetic study comparing SB4 and etanercept reference product (Enbrel®) in healthy subjects.

AIMS: SB4 has been developed as a biosimilar of etanercept. The primary objective of the present study was to demonstrate the pharmacokinetic (PK) equivalence between SB4 and European Union -sourced etanercept (EU-ETN), SB4 and United States-sourced etanercept (US-ETN), and EU-ETN and US-ETN. The safety and immunogenicity were also compared between the treatments. METHODS: This was a single-blind, three-part, crossover study in 138 healthy male subjects. In each part, 46 subjects were randomized at a 1:1 ratio to receive a single 50 mg subcutaneous dose of the treatments (part A: SB4 or EU-ETN; part B: SB4 or US-ETN; and part C: EU-ETN or US-ETN) in period 1, followed by the crossover treatment in period 2 according to their assigned sequences. PK equivalence between the treatments was determined using the standard equivalence margin of 80-125%. RESULTS: The geometric least squares means ratios of AUCinf , AUClast and Cmax were 99.04%, 98.62% and 103.71% (part A: SB4 vs. EU-ETN); 101.09%, 100.96% and 104.36% (part B: SB4 vs. US-ETN); and 100.51%, 101.27% and 103.29% (part C: EU-ETN vs. US-ETN), respectively, and the corresponding 90% confidence intervals were completely contained within the limits of 80-125 %. The incidence of treatment-emergent adverse events was comparable, and the incidence of the antidrug antibodies was lower in SB4 compared with the reference products. CONCLUSIONS: The present study demonstrated PK equivalence between SB4 and EU-ETN, SB4 and US-ETN, and EU-ETN and US-ETN in healthy male subjects. SB4 was well tolerated, with a lower immunogenicity profile and similar safety profile compared with those of the reference products.

Nanotopography facilitates in vivo transdermal delivery of high molecular weight therapeutics through an integrin-dependent mechanism.

Transdermal delivery of therapeutics is restricted by narrow limitations on size and hydrophobicity. Nanotopography has been shown to significantly enhance high molecular weight paracellular transport in vitro. Herein, we demonstrate for the first time that nanotopography applied to microneedles significantly enhances transdermal delivery of etanercept, a 150 kD therapeutic, in both rats and rabbits. We further show that this effect is mediated by remodeling of the tight junction proteins initiated via integrin binding to the nanotopography, followed by phosphorylation of myosin light chain (MLC) and activation of the actomyosin complex, which in turn increase paracellular permeability.

Biodistribution of etanercept to tissues and sites of inflammation in arthritic rats.

Many monoclonal antibodies (mAbs) and other protein drugs have targets usually residing within tissues, making tissue concentrations of mAbs relevant to their pharmacologic effects. Therefore, knowledge of tissue distribution kinetics is important to better understand their pharmacokinetics and pharmacodynamics. The tissue distribution of mAbs is affected by many physiologic factors that may be altered in disease status. In the present work, we studied the tissue distribution kinetics of the fusion protein etanercept in inflamed joint tissues and examined the impact of inflammation on the tissue distribution of etanercept. Etanercept concentration profiles in plasma, blister fluid, and different tissues were obtained from healthy and collagen-induced arthritic (CIA) rats by use of a fluorescence quantification method via IRDye800CW labeling. Stepwise minimal and full physiologically based pharmacokinetic (PBPK) approaches were applied to characterize the distribution kinetics of etanercept in tissues in healthy and diseased animals. Etanercept exhibited modest tissue access (tissue/plasma area under the concentration curve [AUC] ratios 0.03-0.15 and estimated tissue reflection coefficients [σ] of 0.6-1.0), but with good penetration into arthritic paws (tissue/plasma AUC ratio 0.23 and σ 0.36). Etanercept exposure in the inflamed paws of CIA rats was approximately 3-fold higher than in normal paws taken from either CIA or healthy rats (tissue/plasma AUC ratios 0.23 versus 0.07 and σ 0.36 versus 0.71). The tissue distribution kinetics of etanercept in arthritic paws were well characterized with PBPK modeling approaches. Etanercept shows good penetration to arthritic paws in CIA rats. Our study indicates that inflammation produced increased tissue distribution of etanercept in CIA rats.

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.

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

BACKGROUND: TNF-α inhibitor (TNFi) serum trough levels have previously been found to be related to disease activity in axial spondyloarthritis (axSpA). However, most research regarding serum trough levels has been conducted in patients who only recently started TNFi therapy. Therefore, our objective was to explore TNFi serum trough level measurements in relation to disease activity and BMI in the total axSpA population in daily clinical practice, also including patients on long-term TNFi therapy. METHODS: Consecutive patients from the Groningen Leeuwarden Axial Spondyloarthritis (GLAS) cohort were approached for a TNFi serum trough level measurement during their regular outpatient visit at the UMCG. Spearman's correlation coefficient was used to analyse the relation of serum trough levels with disease activity and BMI. Logistic regression was performed to analyse the relation between therapeutic drug levels and disease activity, corrected for potential confounders, including BMI. RESULTS: Thirty-four patients on adalimumab and 21 patients on etanercept were included. Mean age was 45 ± 12 years, 47% were male, median BMI was 26.4 (IQR 23.9-32.5) and median treatment duration was 41 months (range 2-126). According to definitions of Sanquin, 47% of patients had therapeutic serum trough levels. No significant correlations were found between TNFi levels and disease activity (ASDAS-CRP: adalimumab: ρ = -0.16, p = 0.39; etanercept: ρ = -0.29, p = 0.20). TNFi levels were moderately correlated with BMI (adalimumab: ρ = -0.48, p = 0.004; etanercept: ρ = -0.50, p = 0.021). Patients with active disease (ASDAS ≥ 2.1) showed higher BMI than patients with inactive disease (median 29.7 vs. 24.6, p = 0.015). In multivariable regression analyses, BMI was identified as the only confounder for the relationship between therapeutic drug levels and ASDAS. CONCLUSION: In this cross-sectional, observational study of axSpA patients mainly on long-term treatment with TNFi, higher BMI was significantly associated with lower adalimumab and etanercept serum trough levels and higher disease activity.

A novel method for the storage and transport of biological samples of therapeutic proteins prior to the detection of analytes using ELISA.

Therapeutic proteins have exhibited promising clinical applications in the diagnosis and treatment of some diseases. Prior to the detection of analytes using enzyme-linked immunosorbent assay, biological samples of therapeutic proteins are conventionally frozen at temperatures ranging from - 20 to - 80 °C to increase the stability of analytes. However, therapeutic proteins destabilization and aggregation may occur during the frozen storage or the freeze-thawing step. In this work, an effective method was proposed to freeze-dry therapeutic protein samples to allow subsequent storage or transport of samples without freezing them. This new method was validated with quality control samples of adalimumab and etanercept, and it was also used in the bioanalysis of adalimumab and etanercept in pharmacokinetic (PK) studies. Adalimumab and etanercept were stable for 14 days at 4 °C after being prepared and stored using the new method, with detection that was accurate and repeatable. Studies of adalimumab and etanercept in animals and humans showed that the PK parameters of the analytes stored with the new method were consistent with those of analytes stored using the conventional method. This effective method will be attractive for facilitating the storage and transport of plasma samples containing therapeutic proteins.

Comparison of the Pharmacokinetics, Safety, and Tolerability of the Autoinjector (AI) and Pre-Filled Syringe (PFS) of SB4 in Healthy Subjects.

PURPOSE: SB4 is an etanercept biosimilar, approved by the European Commission (EC) and the US Food and Drug Administration (FDA) following a demonstration of equivalent efficacy and safety and comparable quality data to the reference product. This study aimed to demonstrate equivalent pharmacokinetic (PK) profiles, safety, and tolerability between SB4 autoinjector (AI) and SB4 pre-filled syringe (PFS). PATIENTS AND METHODS: This was an open-label, two-period, two-sequence, single-dose, cross-over study to evaluate bioequivalence of PK profiles, safety, and tolerability between SB4 AI and PFS in healthy adults. Treatment periods were separated by 14 days resulting in a 35-day washout between investigational product (IP) administration in Periods 1 and 2. RESULTS: A total of 50 subjects were randomized: 24 subjects in Sequence I and 26 in Sequence II, and 6 subjects discontinued from the study. The primary PK endpoints including area under the concentration-time curve from time zero to infinity (AUCinf) and to the last quantifiable concentration (AUClast), and maximum serum concentration (Cmax) were all within the equivalence margin of 80.00-125.00%. Safety and tolerability were comparable between the two treatments. CONCLUSION: PK profiles showed that SB4 AI and PFS were bioequivalent in healthy subjects. Safety assessment was also comparable between the two treatments.