A Phase 1, randomized, double-blind, placebo-controlled, single- and multiple-dose escalation study to evaluate the safety and pharmacokinetics/pharmacodynamics of PF-06835375, a C-X-C chemokine receptor type 5 directed antibody, in patients with systemic lupus erythematosus or rheumatoid arthritis.

BACKGROUND: The objective of this study was to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of PF­06835375, a potent selective afucosyl immunoglobulin G1 antibody targeting C-X-C chemokine receptor type 5 (CXCR5) that potentially depletes B cells, follicular T helper (Tfh) cells, and circulating Tfh-like (cTfh) cells, in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). METHODS: This first-in-human, multicenter, double-blind, sponsor-open, placebo-controlled Phase 1 study recruited patients aged 18-70 years with SLE or RA. In Part A, patients received single doses of intravenous PF-06835375 (dose range: 0.03-6 mg) or placebo in six sequential single ascending dose (SAD) cohorts. In Part B, patients received repeat doses of subcutaneous PF-06835375 (dose range: 0.3-10 mg) or placebo on Days 1 and 29 in five multiple ascending dose (MAD) cohorts. Tetanus/Diphtheria (Td) and Meningococcal B (MenB/Trumenba™) vaccines were administered at Day 4 (Td and MenB) and Week 8 (MenB only) to assess PF-06835375 functional effects. Endpoints included treatment-emergent adverse events (TEAEs), pharmacokinetic parameters, pharmacodynamic effects on B and cTfh cells, and biomarker counts, vaccine response, and exploratory differential gene expression analysis. Safety, pharmacokinetic, and pharmacodynamic endpoints are summarized descriptively. The change from baseline of B and Tfh cell-specific genes over time was calculated using a prespecified mixed-effects model, with a false discovery rate < 0.05 considered statistically significant. RESULTS: In total, 73 patients were treated (SAD cohorts: SLE, n = 17; RA, n = 14; MAD cohorts: SLE, n = 22; RA, n = 20). Mean age was 53.3 years. Sixty-two (84.9%) patients experienced TEAEs (placebo n = 17; PF-06835375 n = 45); most were mild or moderate. Three (9.7%) patients experienced serious adverse events. Mean t1/2 ranged from 3.4-121.4 h (SAD cohorts) and 162.0-234.0 h (MAD cohorts, Day 29). B and cTfh cell counts generally showed dose-dependent reductions across cohorts (range of mean maximum depletion: 67.3-99.3%/62.4-98.7% [SAD] and 91.1-99.6%/89.5-98.1% [MAD], respectively). B cell-related genes and pathways were significantly downregulated in patients treated with PF-06835375. CONCLUSIONS: These data support further development of PF-06835375 to assess the clinical potential for B and Tfh cell depletion as a treatment for autoimmune diseases. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03334851.

Preclinical evaluation of ELP-004 in mice.

This study provides a detailed understanding of the preclinical pharmacokinetics and metabolism of ELP-004, an osteoclast inhibitor in development for the treatment of bone erosion. Current treatments for arthritis, including biological disease-modifying antirheumatic drugs, are not well-tolerated in a substantial subset of arthritis patients and are expensive; therefore, new treatments are needed. Pharmacokinetic parameters of ELP-004 were tested with intravenous, oral, and subcutaneous administration and found to be rapidly absorbed and distributed. We found that ELP-004 was non-mutagenic, did not induce chromosome aberrations, non-cardiotoxic, and had minimal off-target effects. Using in vitro hepatic systems, we found that ELP-004 is primarily metabolized by CYP1A2 and CYP2B6 and predicted metabolic pathways were identified. Finally, we show that ELP-004 inhibits osteoclast differentiation without suppressing overall T-cell function. These preclinical data will inform future development of an oral compound as well as in vivo efficacy studies in mice.

Bridging the gap in rheumatoid arthritis treatment with hyaluronic acid-based drug delivery approaches.

Rheumatoid Arthritis (RA) is a chronic, inflammatory, auto-immune disease that is majorly associated with the degradation of the synovial linings of the joints. It is a progressive disease that reduces the life span in affected individuals. Nanoparticles involving hyaluronic acid (HA) have gained the limelight for designing target-specific and more effective drug delivery options for RA. HA is found abundantly in the synovial fluid and acts as a natural ligand for the CD44 receptors. The targeted delivery approach using CD44 as the target can help in minimizing off-target drug distribution. These HA-based surface-decorated nanocarriers, hydrogels, and MNs are cutting-edge strategies that promise tailored delivery, fewer side effects, and more patient adherence to address the common issues associated with RA therapy. Considering the above facts, this review attempts to discuss the role of HA in making more effective formulations for therapeutic delivery in treating RA. Additionally, it provides a comprehensive overview of the potential advancements, mainly in treating RA by HA-based topical, transdermal, and parenteral drug delivery systems, with relevant case studies. The existing difficulties and potential paths for future research on HA-based non-conventional formulations for the management of RA are also discussed.

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

OBJECTIVE: Characterise the relationship between hydroxychloroquine (HCQ) blood levels and the number of missed doses, accounting for dosage, dose timing and the large variability in pharmacokinetics (PK) between patients. METHODS: We externally validated a published PK model and then conducted dosing simulations. We developed a virtual population of 1000 patients for each dosage across a range of body weights and PK variability. Using the model, 10 Monte Carlo simulations for each patient were conducted to derive predicted whole blood concentrations every hour over 24 hours (240 000 HCQ levels at steady state). To determine the impact of missed doses on levels, we randomly deleted a fixed proportion of doses. RESULTS: For patients receiving HCQ 400 mg daily, simulated random blood levels <200 ng/mL were exceedingly uncommon in fully adherent patients (<0.1%). In comparison, with 80% of doses missed, approximately 60% of concentrations were <200 ng/mL. However, this cut-off was highly insensitive and would miss many instances of severe non-adherence. Average levels quickly dropped to <200 ng/mL after 2-4 days of missed doses. Additionally, mean levels decreased by 29.9% between peak and trough measurements. CONCLUSIONS: We propose an algorithm to optimally interpret HCQ blood levels and approximate the number of missed doses, incorporating the impact of dosage, dose timing and pharmacokinetic variability. No single cut-off has adequate combinations of both sensitivity and specificity, and cut-offs are dependent on the degree of targeted non-adherence. Future studies should measure trough concentrations to better identify target HCQ levels for non-adherence and efficacy.

Self-actuating inflammation responsive hydrogel microsphere formulation for controlled drug release in rheumatoid arthritis (RA): Animal trials and study in human fibroblast like synoviocytes (hFLS) of RA patients.

Patients with rheumatoid arthritis (RA) often have one or more painfuljoints despite adequate medicine. Local drug delivery to the synovial cavity bids for high drug concentration with minimal systemic adverse effects. However, anti-RA drugs show short half-lives in inflamed joints after intra-articular delivery. To improve the therapeutic efficacy, it is essential to ensure that a drug is only released from the formulation when it is needed. In this work, we developed an intelligent "Self-actuating" drug delivery system where Disease-modifying anti-rheumatic Drug (DMARD) methotrexate is incorporated within a matrix intended to be injected directly into joints. This formulation has the property to sense the need and release medication only when joints are inflamed in response to inflammatory enzyme Matrix metalloproteinases (MMP). These enzymes are important proteases in RA pathology, and several MMP are present in augmented levels in synovial fluid and tissues. A high level of MMP present in synovial tissues of RA patients would facilitate the release of drugs in response and ascertain controlled drug release. The formulation is designed to be stable within the joint environment, but to dis-assemble in response to inflammation. The synthesized enzyme-responsive methotrexate (Mtx) encapsulated micron-sized polymer-lipid hybrid hydrogel microspheres (Mtx-PLHM) was physiochemically characterized and tested in synovial fluid, Human Fibroblast like synoviocytes (h-FLS) (derived from RA patients) and a rat arthritic animal model. Mtx-PLHM can self-actuate and augment the release of Mtx drug upon contact with either exogenously added MMP or endogenous MMP present in the synovial fluid of patients with RA. The drug release from the prepared formulation is significantly amplified to several folds in the presence of MMP-2 and MMP-9 enzymes. In the rat arthritic model, Mtx-PLHM showed promising therapeutic results with the significant alleviation of RA symptoms through decrease in joint inflammation, swelling, bone erosion, and joint damage examined by X-ray analysis, histopathology and immune-histology. This drug delivery system would be nontoxic as it releases more drug only during the period of exacerbation of inflammation. This will simultaneously protect patients from unwanted side effects when the disease is inactive and lower the need for repeated joint injections.

Synergistically engineered nanotransethosomes for co-delivery of methotrexate and baicalin for enhanced transdermal delivery against rheumatoid arthritis: formulation, characterisation and in vivo pharmacodynamic evaluation.

Background: Rheumatoid arthritis (RA) is a systemic autoimmune disease that significantly impacts the quality of life of those affected. Owing to the complex pathophysiology of RA, it is not possible for any singular treatment to entirely impede the progression of the disease. Hence, the current study aimed to adopt a holistic and synergistic approach towards the management of RA by means of a co-delivery strategy involving methotrexate (MTH), a conventional slow-acting anti-rheumatic drug, and baicalin (BCN), a bioactive phytochemical using a transethosomal (TRS) gel formulation.Purpose: The present study aims to evaluate the potential benefits of administering MTH and BCN in nanoparticulate form, which may lead to improved stability and solubility, as well as enhanced penetration into the arthritic tissues of interest.Methods and results: The MTH-BCN-TRS that were synthesised exhibited small particle size of 151.3 nm and polydispersity index of 0.125, as well as a favourable zeta potential of -32.22 mV. Additional assessments were conducted, including a pharmacokinetic analysis, TEM, skin permeation analysis and confocal microscopy. According to the Confocal laser scanning microscopy (CLSM) study, the formulated MTH-BCN-TRS gel exhibited superior MTH and BCN permeation through the skin layers when compared to the MTH-BCN suspension gel. The MTT experiment on Raw 264.7 and SW982 cell lines revealed a considerable reduction (p < .05) in the IC50 value of the MTH-BCN-TRS formulation (9.2 mM and 43.2 mM, respectively) in comparison to the drug suspension. According to the findings of the in vivo study, it was found that the MTH-BCN-TRS gel exhibits significantly promising anti-arthritic properties when compared to the conventional diclofenac gel. This was demonstrated through histopathological studies and radiographic analysis. Furthermore, skin irritation investigation on Wistar albino rats confirmed that the formulated MTH-BCN-TRS is a safe option for topical treatment on the skin. The present study has confirmed that the formulated TRS vesicles are a valuable carrier for the transdermal delivery of MTH and BCN, which may be used for the management of rheumatoid arthritis.

Population Pharmacokinetics of Adalimumab in Juvenile Idiopathic Arthritis Patients: A Retrospective Cohort Study Using Clinical Care Data.

BACKGROUND AND OBJECTIVE: Juvenile idiopathic arthritis (JIA) is a chronic autoimmune disorder that primarily affects the joints in children. Notably, it is known to co-occur with uveitis. Adalimumab, a monoclonal anti-TNF antibody, is effective in treating both conditions. A deeper understanding of the pharmacokinetics (PK) of adalimumab in JIA is crucial to advance in more personalized treatment approaches. The objective of this study is to evaluate the population PK profile of adalimumab in JIA and to explain causes for its variability. MATERIALS AND METHODS: Adalimumab and antidrug antibody concentrations were retrospectively retrieved from the charts of patients with JIA. Initially, five literature-based population PK models of adalimumab were evaluated to assess their ability to describe the observed concentration-time profiles in the JIA cohort. These models included one specifically for the pediatric Crohn's disease population and four derived from studies in adult populations in healthy subjects and rheumatoid arthritis patients. Subsequently, a novel population PK model tailored to the JIA population was developed using NONMEM software. Monte Carlo simulations were then conducted utilizing the final PK model to visualize the concentration-time profile of adalimumab in patients with JIA and the impact of covariates. RESULTS: A cohort of 50 patients with JIA with 78 available adalimumab samples was assessed. The mean age was 11.8 ± 3.9 years, with a median body weight of 49 kg (interquartile range 29.4-59.8 kg). All literature models adequately described the concentration-time profiles in JIA. The best model, which was developed in patients with rheumatoid arthritis during the maintenance phase of treatment, served as a basis for estimating clearance in JIA, resulting in a value of 0.37 L per day per 70 kg. Patient body weight, antidrug antibodies, methotrexate use, CRP level, and comorbidity of uveitis were found to have a significant impact on adalimumab clearance, and these reduced the inter-patient variability from 58.6 to 28.0%. On steady state in the simulated patient population, the mean trough level was 7.4 ± 5.5 mg/L. The two dosing regimens of 20 and 40 mg every other week, based on patients' body weight, resulted in comparable simulated overall drug exposure. CONCLUSIONS: Five literature models effectively described adalimumab PK in this pediatric cohort, highlighting the potential for extrapolating existing models to the pediatric population. The new JIA model confirmed the effect of several known covariates and found a novel association for drug clearance with methotrexate use (lower) and uveitis (higher), which might have clinical relevance for personalized dosing in JIA.

'Totality of Evidence' Approach in the Development of GP2017, an Approved Adalimumab Biosimilar.

INTRODUCTION: Hyrimoz®, (GP2017 [SDZ-ADL]), is a biosimilar to Humira® (REF-ADL). SDZ-ADL was approved in 2018 by both the United States Food and Drug Administration (US FDA) and European Medicines Agency (EMA) for the indications of REF-ADL not protected by orphan exclusivity. In 2023, the US FDA and EMA also approved a citrate-free high-concentration formulation (HCF) of SDZ-ADL. TOTALITY OF EVIDENCE-THE APPROACH: Approval of SDZ-ADL was based on data gathered using the US FDA, EMA and World Health Organization (WHO)-recommended step-wise Totality of Evidence approach. This approach is a robust dataset confirming high confidence in analytical, functional, pharmacokinetic (PK) and clinical biosimilarity between the biosimilar and reference medicine determined through analytical and clinical investigation. EVIDENCE OF BIOSIMILARITY: Evidence supporting the biosimilarity of SDZ-ADL and REF-ADL was reported at each stage of investigation. Comprehensive comparative analytical and functional assessments demonstrated that SDZ-ADL was analytically indistinguishable from REF-ADL in required critical quality attributes, including receptor binding. Phase I clinical data showed PK similarity of SDZ-ADL and REF-ADL in healthy volunteers, with similar safety, tolerability and immunogenicity profiles. Phase III confirmatory efficacy and safety studies, ADACCESS (included in US/EU dossiers) and ADMYRA (separate to US/EU dossiers), both confirmed that SDZ-ADL's efficacy, safety, and immunogenicity matched REF-ADL in all patient groups with no clinically meaningful differences. More recently, this data package was the basis for a citrate-free HCF of SDZ-ADL to be developed, and its PK, safety and immunogenicity were confirmed against the initially approved formulation of SDZ-ADL. CONCLUSION: Overall, the Totality of Evidence provided for biosimilar adalimumab, SDZ-ADL, confirmed the analytical, functional and clinical similarity of SDZ-ADL to REF-ADL, supporting its regulatory approval and providing a data bridge with which to evaluate and support the approval of citrate-free HCF SDZ-ADL for clinical use.

A biosimilar is a type of medicine that is designed to match the structure and function of a 'reference' biologic medicine. Hyrimoz^® (SDZ-ADL) is a biosimilar of the adalimumab reference medicine, Humira^® ([REF-ADL]). SDZ-ADL was approved in the US and Europe in 2018. For SDZ-ADL to be approved, a collection of evidence needed to be created, called the 'Totality of Evidence.' The purpose of this collection of data is to show there is a high confidence that the new biosimilar medicine matches the reference medicine, from the structure of the medicine to the effect of the medicine on the human body. For SDZ-ADL, this investigation started with comparing the physical structure and other functional properties of SDZ-ADL versus REF-ADL and ended with clinical studies in both healthy volunteers and in patients with diseases treated with adalimumab. This Totality of Evidence gathered for biosimilar adalimumab, SDZ-ADL, confirmed the similarity of SDZ-ADL to REF-ADL and therefore supported the approval of SDZ-ADL. In 2018, a citrate-free high-concentration version (high concentration formulation [HCF]) of REF-ADL was launched that matched REF-ADL. HCF REF-ADL has since become the primary formulation of REF-ADL used in practice. In 2023, a HCF version of SDZ-ADL was also approved in the US and EU based on evidence confirming that HCF SDZ-ADL matched SDZ-ADL. As SDZ-ADL had been previously confirmed to match the reference medicine, this meant that HCF SDZ-ADL could be directly compared against SDZ-ADL to confirm biosimilarity and support its approval.

A population pharmacokinetic model using allometric scaling for baricitinib in patients with juvenile idiopathic arthritis.

Baricitinib is approved for the treatment of rheumatoid arthritis (RA) in more than 70 countries, and juvenile idiopathic arthritis (JIA) in the European Union. Population pharmacokinetic (PK) models were developed in a phase 3 trial to characterize PK in pediatric patients with JIA and identify weight-based dosing regimens. The phase 3, randomized, double-blind, placebo-controlled withdrawal, efficacy and safety trial, JUVE-BASIS, enrolled patients (aged 2 to <18 years) with polyarticular course JIA. During a safety/PK period, baricitinib concentration data from age-based dose cohorts were compared to concentrations from adult patients receiving 4-mg QD. PK data were used to develop a population PK model with allometric scaling to determine a weight-based posology in pediatric patients with JIA that matched the adult 4-mg exposure. Baricitinib plasma concentrations from 217 pediatric patients were used to characterize PK. Based on the adult model, pediatric PK was best described using a 2-compartment model with allometric scaling on clearance and volume of distribution and renal function (estimated with glomerular filtration rate [GFR], a known covariate affecting PK of baricitinib) on clearance. The PK modeling suggested the optimal dosing regimen based on weight for pediatric patients as: 2-mg QD for patients 10 to <30 kg and 4-mg QD for patients ≥30 kg. The use of a population PK model of baricitinib treatment in adult patients with RA, with the addition of allometric scaling for weight on clearance and volume terms, was useful to predict exposures and identify weight-based dosing in pediatric patients with JIA.

Tocilizumab Dose Tapering Based on a Model-Based Algorithm is Feasible in Clinical Practice: A Short Communication.

BACKGROUND: Tocilizumab in the treatment of rheumatoid arthritis (RA) is a potential candidate for concentration-guided tapering because the standard dose of tocilizumab results in a wide range of serum concentrations, usually above the presumed therapeutic window, and an exposure-response relationship has been described. However, no clinical trials have been published to date on this subject. Therefore, the objective of this study was to assess the feasibility of the tapering of intravenous (iv) tocilizumab with the use of a pharmacokinetic model-based algorithm in RA patients. METHODS: A randomized controlled trial with a double-blind design and follow-up of 24 weeks was conducted. RA patients who received the standard of tocilizumab for at least the past 24 weeks, which is 8 mg/kg every 4 weeks, were included. Patients with a tocilizumab serum concentration above 5 mg/L at trough were randomized between concentration-guided dose tapering, referred to as therapeutic drug monitoring (TDM), or the standard 8 mg/kg dose. In the TDM group, the tocilizumab dose was tapered with a recently published model-based algorithm to achieve a target concentration of 4-6 mg/L after 20 weeks of dose tapering. RESULTS: Twelve RA patients were included and 10 were randomized between the TDM and standard dose group. The study was feasible regarding the predefined feasibility criteria and patients had a positive attitude toward therapeutic drug monitoring. In the TDM group, the tocilizumab trough concentration within patients decreased on average by 24.5 ± 18.3 mg/L compared with a decrease of 2.8 ± 12 mg/L in the standard dose group. None of the patients in the TDM group reached the drug range of 4-6 mg/L. Instead, tocilizumab concentrations of 1.6 and 1.5 mg/L were found for the 2 patients who completed follow-up on the tapered dose. No differences in RA disease activity were observed between the 2 study groups. CONCLUSIONS: This study was the first to show that it is feasible to apply a dose-reduction algorithm based on a pharmacokinetic model in clinical practice. However, the current algorithm needs to be optimized before it can be applied on a larger scale.

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.

Intra-articular Injection of a B Cell Depletion Antibody Enhances Local Exposure to the Joint-Draining Lymph Node in Mice with Collagen-Induced Arthritis.

Changes to the number, type, and function of immune cells within the joint-draining lymphatics is a major contributor to the progression of inflammatory arthritis. In particular, there is a significant expansion in pathogenic B cells in the joint-draining lymph node (jdLN). These B cells appear to clog the lymphatic sinuses in the lymph node, inhibit lymph flow, and therefore, reduce the clearance of inflammatory fluid and cells from the joint. Taken together, there is potential to treat inflammatory arthritis more effectively, as well as reduce off-target side effects, with localized delivery of B-cell depleting therapies to the jdLNs. We recently reported that joint-draining lymphatic exposure of biologic disease-modifying anti-rheumatic drugs (DMARDs), including the B cell depletion antibody rituximab, is increased in healthy rats following intra-articular (IA) compared to subcutaneous (SC) or intravenous (IV) administration. This suggests that IA administration of B cell depleting antibodies may increase delivery to target cells in the jdLN and increase the effectiveness of B cell depletion compared to standard SC or IV administration. However, whether enhanced local delivery of DMARDs to the jdLN is also achieved after IA injection in the setting of inflammatory arthritis, where there is inflammation in the joint and jdLN B cell expansion is unknown. We, therefore, assessed the lymph node distribution, absorption and plasma pharmacokinetics, and B cell depletion at different sites after IA, SC, or IV administration of a fluorescently labeled mouse anti-CD20 B cell depleting antibody (Cy5-αCD20) in healthy mice compared to mice with collagen-induced arthritis (CIA). The absorption and plasma pharmacokinetics of Cy5-αCD20 appeared unaltered in mice with CIA whereas distribution of Cy5-αCD20 to the jdLNs was generally increased in mice with CIA, regardless of the route of administration. However, IA administration led to greater and more specific exposure to the jdLNs. Consistent with increased Cy5-αCD20 in the jdLNs of CIA compared to healthy mice, there was a greater reduction in jdLN weight and a trend toward greater jdLN B cell depletion at 24 h compared to 4 h after IA compared to SC and IV administration. Taken together, this data supports the potential to improve local efficacy of B cell depletion therapies through a jdLN-directed approach which will enable a reduction in dose and systemic toxicities.

Factors influencing methotrexate and methotrexate polyglutamate in patients with rheumatoid arthritis: a systematic review of population pharmacokinetics.

Low dose methotrexate (MTX) is commonly used in the treatment of rheumatoid arthritis. The clinical effect is mediated by its metabolite, methotrexate polyglutamate (MTX-PGn). The drug exhibits high interindividual pharmacokinetic variability and the optimal MTX dose is different among individuals. Thus, several MTX population pharmacokinetic (PopPK) models were developed to characterize factors affecting MTX pharmacokinetic variability. This review summarizes significant predictors for MTX pharmacokinetics and identifies knowledge gaps to be further examined. A total of 359 articles were identified from a systematic search of four databases: PubMed, Science Direct, and CINAHL Complete. Of these eight studies were included. Most studies investigated influential factors on MTX pharmacokinetics, but information on MTX-PGn is limited, with only one study performing a parent-metabolite (MTX-PG3) model. MTX pharmacokinetics was described using a two-compartment model with first-order elimination in most studies, with the MTX clearance ranging from 6.94 to 12.39 L/h. Significant predictors influencing MTX clearance included weight, creatinine clearance, sex, OATP1B3 polymorphism, and MTX multiple dosing. While body mass index and red blood cell counts were significant predictors for MTX-PG3 clearance. Providing that MTX-PGn plays a crucial role in clinical effect, further studies should determine other factors affecting MTX-PGn as well as its relationship with clinical response.

Potential application of measuring serum infliximab levels in rheumatoid arthritis management: A retrospective study based on KURAMA cohort data.

Infliximab (IFX) therapy has considerably improved the treatment of rheumatoid arthritis (RA). However, some patients still do not respond adequately to IFX therapy, or the efficacy of the treatment diminishes over time. Although previous studies have reported a relationship between serum IFX levels and therapeutic efficacy, the potential applications of IFX therapeutic drug monitoring (TDM) in clinical practice remain unclear. The purpose of this study was to investigate the potential applications of IFX TDM by analyzing a Japanese cohort database. Data were collected retrospectively from the Kyoto University Rheumatoid Arthritis Management Alliance cohort between January 1, 2011, and December 31, 2018. Serum IFX levels were measured using a liquid chromatography-tandem mass spectrometer. Out of the 311 RA patients that used IFX, 41 were eligible for the analysis. Serum IFX levels were significantly higher in responders than in non-responders. An optimal cut-off value was determined to be 0.32 µg/mL based on a receiver operating characteristic curve. At the IFX measurement point, a better therapeutic response was observed in the high IFX group (n = 32) than in the low IFX group (n = 9). Conversely, at the maximum effect point, when DAS28-ESR was the lowest between IFX introduction and measurement points, there were no differences in responder proportions between the low and high IFX groups. IFX primary ineffectiveness could be avoided with appropriate dose escalation without blood concentration measurement in clinical practice. In conclusion, IFX TDM could facilitate the identification of secondary non-responders and in turn, proper IFX use.

Kinetic analysis of cystine uptake and inhibition pattern of sulfasalazine in A549 cells.

Cystine/glutamate transporter (xCT) is an antiporter involved in cystine uptake and glutamate efflux. However, there are very few reports regarding the kinetic analysis of xCT for cystine uptake using cancer cell lines, as well as the inhibition pattern of sulfasalazine, an inhibitor of xCT, for cystine uptake. Therefore, the purpose of this study was to clarify the kinetics of xCT in A549 cells, human lung cancer cells, and to reveal the inhibition pattern of sulfasalazine. Cystine uptake occurred in a time-dependent manner, with linear cystine uptake observed for 5 min. Additionally, sulfasalazine inhibited cystine uptake in a concentration-dependent manner, presenting an IC50 value of 24.7 ± 5.6 µM. Cystine uptake was saturated with increasing concentration, demonstrating Km and Vmax values of 179.4 ± 26.7 µM and 30.4 ± 2.3 nmol/min/mg protein, respectively. Moreover, during cystine uptake with sulfasalazine, Km and Vmax were >300 µM and 8.0 ± 1.5 nmol/min/mg protein, respectively, suggesting that sulfasalazine might demonstrate a mixed inhibition pattern. Furthermore, xCT siRNA decreased the xCT mRNA level and reduced cystine uptake. In conclusion, xCT was involved in the cystine uptake in A549 cells and sulfasalazine showed a mixed inhibition pattern to xCT.

Factors contributing to discrepant estimated glomerular filtration values measured by creatinine and cystatin C in patients with rheumatoid arthritis.

This study aimed to clarify the factors underlying the discrepancy that has been noted between estimated glomerular filtration ratio (eGFR) measured using serum creatinine (Cr) and eGFR using serum cystatin C (CysC) in patients with rheumatoid arthritis (RA) and to identify those patients whose renal function should be evaluated using CysC. We retrospectively evaluated clinical features, disease activity, Steinbrocker radiological staging, and co-morbidities (diabetes mellitus, hypertension, dyslipidemia) in 238 RA patients. eGFR using serum creatinine (eGFR-Cr) and eGFR using serum cystatin C (eGFR-CysC) were calculated using the new Japanese coefficient-modified Modification of Diet in Renal Disease study equation. To clarify the cause(s) of differences of 20% or more between the two eGFRs, we divided our RA patients into Group A (eGFR-Cr/eGFR-CysC ≥ 1.2) and Group B (eGFR-Cr/eGFR-CysC < 1.2), and searched for factors independently related to Group A. Forty-five patients (18.9%) were assigned to Group A, and 193 (81.1%) to Group B. BMI (Odds Ratio [OR] 0.820, 95% confidence interval [CI] 0.675-0.996), Hb (OR 0.633, 95% CI 0.433-0.926), CK (OR 0.773 per 10 units, 95% CI 0.644-0.933), NSAID use (OR 0.099, 95% CI 0.020-0.494), diabetes mellitus (OR 6.024, 95% CI 1.508-24.390) and stage 4 Steinbrocker radiological stage (OR 10.309, 95% CI 2.994-35.714) were identified as independent relevant factors for Group A by a multifactorial analysis. Renal function in RA patients with low BMI, diabetes, anemia and low CK may be overestimated using eGFR-Cr alone, and such patients need to be evaluated using eGFR-CysC.

A comprehensive strategy to clarify the pharmacodynamic constituents and mechanism of Wu-tou decoction based on the constituents migrating to blood and their in vivo process under pathological state.

ETHNOPHARMACOLOGICAL RELEVANCE: As a traditional Chinese medicine (TCM) formula, Wu-tou decoction has been used for treating rheumatoid arthritis (RA) for more than a thousand years. Identifying pharmacodynamic constituents (PCs) of WTD and exploring their in vivo process are very meaningful for promoting the modernization of TCM. However, the pathological state might change this process. AIM OF THE STUDY: Hence, it is necessary and significant to compare the process in vivo of drugs both in normal and disease state and clarify their action mechanism. MATERIALS AND METHODS: Taking Wu-tou decoction (WTD) as the research object, a comprehensive strategy based on liquid chromatography coupled with mass spectrometry (LC-MS) was developed to identify PCs, clarify and compare their absorption and distribution in normal and model rats, and then explore the potential mechanism of TCM. Firstly, the PCs in WTD were identified. Then, the pharmacokinetics (PK) and tissue distribution of these ingredients were studied. Finally, the constituents with the difference between normal and model rats were selected for target network pharmacological analysis to clarify the mechanism. RESULTS: A total of 27 PCs of WTD were identified. The absorption and distribution of 20 PCs were successfully analyzed. In the disease state, the absorption and distribution of all these components were improved to have better treatment effects. The results of target network pharmacological analysis indicated that PTGS1, PTGS2, ABCB1, SLC6A4, CHRM2, ESR1, ESR2, CDK2, TNF and IL-6 are 10 key targets for WTD against RA. The regulatory effects of WTD on the expression of PTGS2 and TNF were further verified. Pathway enrichment analysis showed that the key mechanism of WTD against RA is to reduce inflammation and regulate the immune response. CONCLUSION: These results indicated that this strategy could better understand the in vivo process and mechanism of WTD under the pathological state. Furthermore, this strategy is also appropriate for other TCM.

Association of adalimumab trough concentrations and treatment response in patients with juvenile idiopathic arthritis.

OBJECTIVE: The objective of this study was to assess the relationship between adalimumab trough concentrations and treatment response in paediatric patients with JIA. METHODS: This was a monocentric cohort study of JIA patients treated with adalimumab. Clinical data and samples were collected during routine follow-up. Adalimumab trough concentrations were quantified by a novel liquid chromatography-tandem mass spectrometry assay. Anti-adalimumab antibodies were measured in samples with trough concentrations of ≤5mg/l. Disease activity was evaluated using the clinical Juvenile Arthritis DAS with 71-joint count (cJADAS71). Response to adalimumab was defined according to recent international treat-to-target guidelines. RESULTS: A total of 35 adalimumab trough samples were available from 34 paediatric patients with JIA. Although there was no significant difference in adalimumab dose, trough concentrations were significantly lower in patients with secondary failure [median 1.0 mg/l; interquartile range (IQR) 1.0-5.3] compared with patients with primary failure (median 13.97 mg/l; IQR 11.81-16.67) or an adequate response (median 14.94 mg/l; IQR 10.31-16.19) to adalimumab. CONCLUSION: Adalimumab trough concentrations were significantly lower in JIA patients with secondary failure compared with patients with primary failure or an adequate response to adalimumab. Our results suggest that trough concentration measurements could identify JIA patients who require increased adalimumab doses to achieve or maintain therapeutic drug concentrations.

Effect of total glucosides of paeony and Tripterygium wilfordii polyglycosides on erythrocyte methotrexate polyglutamates in rats, analysed using ultra-high-performance liquid chromatography-tandem mass spectrometry.

OBJECTIVES: The aim of the study was to explore the effect of total glucosides of paeony (TGP) and Tripterygium wilfordii polyglycosides (TWP) on erythrocyte methotrexate polyglutamates (MTXPGs), the metabolites of methotrexate (MTX). METHODS: An ultra-high-performance liquid chromatography (UPLC)-tandem mass spectrometry (MS/MS) method was developed to determine MTXPGs. The effects of MTXPGs were analysed using 24 male Sprague-Dawley rats that were randomly divided into the MTX alone, MTX-TGP combined, and MTX-TWP combined groups. Rats were administered MTX at a dose of 0.9 mg/kg once a week, TGP at 0.054 g/kg and TWP at 1.8 mg/kg three times a day. Venous blood (1.0 ml) was collected at weeks 2, 4, 6, 9, 12 and 15 and then analysed using the developed UPLC-MS/MS method. KEY FINDINGS: Specificity, linear range, inter-and intra-day precision, recovery, matrix effect and stability of MTXPGs met the standard regulations. This method was successfully used for the detection of MTXPGs. After administration of MTX alone, erythrocyte MTXPGs increased and accumulated in a time- and dose-dependent manner. Compared to MTX alone, the combination with TGP significantly decreased the content of total MTXPGs and short-chain MTXPGs (Methotrexate [MTX/MTXPG1] and 4-amino-10-methylpteroyldiglutamic acid [MTXPG2], P < 0.05), but had no significant effect on long-chain MTXPGs (4-amino-10-methylpteroyltriglutamic acid [MTXPG3], P > 0.05) and very long-chain MTXPGs (4-amino-10-methylpteroyltetraglutamic acid [MTXPG4] and 4-amino-10-methylpteroylpentaglutamic acid [MTXPG5], P > 0.05) at week 15. The combination of MTX with TWP had no significant effect on the content of total MTXPGs, short-chain MTXPGs and long-chain MTXPGs (P > 0.05), but it significantly decreased the content of very long-chain MTXPGs (P < 0.05) at week 15. CONCLUSIONS: The UPLC-MS/MS method was successfully used to determine MTXPGs in rat erythrocytes. TGP and TWP in combination with MTX affected the production of MTXPGs of different chain lengths in erythrocytes.

Methotrexate Triglutamate as a Determinant of Clinical Response in Mexican Patients With Rheumatoid Arthritis: Pharmacokinetics and Dose Recommendation.

Methotrexate is the gold standard treatment in rheumatoid arthritis. Once absorbed, it is internalized in cells, where glutamate residues are added to produce polyglutamated forms, which are responsible for the effect of methotrexate. The aim of the current study is to determine the relationship between methotrexate triglutamate concentrations and the clinical evolution in rheumatoid arthritis patients, as well as to characterize the variability in both features to propose strategies for low-dose methotrexate optimization. The quantification of methotrexate triglutamate concentration in red blood cells was performed through ultra-performance liquid chromatography coupled with mass spectrometry. Polymorphisms of genes involved in the formation of polyglutamates were determined by real-time polymerase chain reaction. A multivariate regression was performed to determine the covariates involved in the variability of methotrexate triglutamate concentrations and a population pharmacokinetics model was developed through nonlinear mixed-effects modeling. Disease activity score changed according to methotrexate triglutamate concentrations; patients with good response to treatment had higher concentrations than moderate or nonresponding patients. The methotrexate triglutamate concentrations were related to time under treatment, dose, red blood cells, and body mass index. A 1-compartment open model was selected to estimate the pharmacokinetic parameters; the typical total clearance (L/day) was determined as 1.45 * (body mass index/28 kg/m2 ) * (red blood cells/4.6 × 106 cells/µL) and the volume of distribution was 52.4 L, with an absorption rate of 0.0346/day and a fraction metabolized of 1.03%. Through the application of the model, the initial dose of methotrexate is proposed on the basis of stochastic simulations and considering methotrexate triglutamate concentrations found in responders patients.