Population pharmacokinetics of tofacitinib in patients with psoriatic arthritis

Exposure-Response Analysis of Tofacitinib in Active Psoriatic Arthritis: Results from Two Phase 3 Studies

Tofacitinib is an oral Janus kinase inhibitor for the treatment of psoriatic arthritis (PsA). These post hoc exposure-response (E-R) analyses of pooled data from two Phase 3 studies (NCT01877668 and NCT01882439) characterized the relationships between tofacitinib exposure and efficacy (American College of Rheumatology [ACR] criteria), and changes in hemoglobin (Hgb) in patients with PsA. Efficacy data for the proportion of patients receiving tofacitinib 5 or 10 mg twice daily, or placebo, achieving ACR ≥20%, ≥50%, or ≥70% response criteria (ACR20, ACR50, and ACR70, respectively) at Month 3, were modeled jointly using a four-category ordered categorical exposure-response model (ACR20 non-responder, ACR20 responder but not ACR50 responder, ACR50 responder but not ACR70 responder, and ACR70 responder). A maximum drug effect (Emax) model (using average concentrations of tofacitinib at steady state [Cavg]) adequately described the exposure-ACR response rate relationship. Model-predicted response rates for tofacitinib 5 and 10 mg twice daily were 51% and 58%, respectively, for ACR20; 29% and 36% for ACR50; and 15% and 20% for ACR70. The E-R relationship between tofacitinib exposure and changes in Hgb was assessed using an indirect response model, which generally predicted Hgb concentration-time profiles across treatments well. The proportions of patients experiencing a decrease in Hgb of >2 g/dL were similar with tofacitinib 5 mg twice daily or placebo. These results were generally consistent with previous analyses in rheumatoid arthritis and psoriasis, and support the use of tofacitinib 5 mg twice daily for active PsA.

Knowledge, attitude, and practice of psoriatic arthritis among patients with psoriasis

Introduction

This study aimed to investigate the knowledge, attitude and practice (KAP) of psoriatic arthritis among patients with psoriasis. The KAP questionnaire is a widely used tool in public health research, designed to assess individuals' understanding (knowledge), beliefs (attitude), and behaviors (practice) related to a specific health condition.

Methods

A cross-sectional study was conducted at Sinopharm Dongfeng General Hospital from September to November 2023. Demographic information and KAP scores were assessed using a structured questionnaire, which evaluated patient knowledge about psoriatic arthritis, their attitude toward managing it, and their practical engagement in preventive or treatment behaviors.

Results

In this study, 392 valid questionnaires were analyzed. Of these, 290 respondents (74.0%) were male, and 296 (75.5%) reported no comorbid conditions. The median scores for knowledge, attitude, and practice were 8 (interquartile range [IQR]: 6-10), 21 (IQR: 19-24), and 14 (IQR: 8-22), respectively. Multivariate logistic regression analysis indicated that practice was independently associated with being female (OR = 0.426, 95% CI: 0.259-0.703, p = 0.001), being aged 30-39 years (OR = 2.159, 95% CI: 1.223-3.811, p = 0.008) or 40-49 years (OR = 2.002, 95% CI: 1.019-3.936, p = 0.044), having a Dermatology Life Quality Index (DLQI) score of 11-30 (OR = 2.569, 95% CI: 1.158-5.700, p = 0.020), and not having psoriatic arthritis (OR = 0.300, 95% CI: 0.168-0.537, p < 0.001).

Conclusion

Patients with psoriasis had suboptimal knowledge, positive attitude and inactive practice toward psoriatic arthritis. To address this, healthcare providers should prioritize educational interventions, with a specific focus on younger patients, females, and individuals with a higher DLQI score, to enhance awareness and promote proactive management of psoriatic arthritis among this patient population.

Non-kinase off-target inhibitory activities of clinically-relevant kinase inhibitors

Protein kinases are responsible for a myriad of cellular functions, such as cell cycle, apoptosis, and proliferation. Because of this, kinases make excellent targets for therapeutics. During the process to identify clinical kinase inhibitor candidates, kinase selectivity profiles of lead inhibitors are typically obtained. Such kinome selectivity screening could identify crucial kinase anti-targets that might contribute to drug toxicity and/or reveal additional kinase targets that potentially contribute to the efficacy of the compound via kinase polypharmacology. In addition to kinome panel screening, practitioners also obtain the inhibition profiles of a few non-kinase targets, such as ion-channels and select GPCR targets to identify compounds that might possess potential liabilities. Often ignored is the possibility that identified kinase inhibitors might also inhibit or bind to the other proteins (greater than 20,000) in the cell that are not kinases, which may be relevant to toxicity or even additional mode of drug action. This review highlights various inhibitors, which have been approved by the FDA or are currently undergoing clinical trials, that also inhibit other non-kinase targets. The binding poses of the drugs in the binding sites of the target kinases and off-targets are analyzed to understand if the same features of the compounds are critical for the polypharmacology.

Clinical pharmacokinetics and pharmacodynamics of oral systemic nonbiologic therapies for psoriasis patients

INTRODUCTION

Psoriasis is a chronic inflammatory immune condition. Treatments for psoriasis vary with disease severity, ranging from topicals to systemic biologic agents. The pharmacokinetic (PK) and pharmacodynamic (PD) properties of these therapies establish drug efficacy, toxicity, and optimal dosing to ensure therapeutic drug levels are sustained and adverse effects are minimized.

AREAS COVERED

A literature search was performed on PubMed, Google Scholar, and Ovid MEDLINE for PK and PD, efficacy, and safety data regarding oral systemic nonbiologic therapies utilized for moderate-to-severe plaque psoriasis. The findings were organized into sections for each drug: oral acitretin, methotrexate, cyclosporine, apremilast, tofacitinib, and deucravacitinib.

EXPERT OPINION

Some psoriasis patients may not respond to initial therapy. Ongoing research is evaluating genetic polymorphisms that may predict an improved response to specific medications. However, financial and insurance barriers, as well as limited genetic polymorphisms correlated with treatment response, may restrict the implementation of genetic testing necessary to personalize treatments. How well psoriasis patients adhere to treatment may contribute greatly to variation in response. Therapeutic drug monitoring may help patients adhere to treatment, improve clinical response, and sustain disease control.

Tofacitinib pharmacokinetics in children and adolescents with juvenile idiopathic arthritis

These analyses characterized tofacitinib pharmacokinetics (PKs) in children and adolescents with juvenile idiopathic arthritis (JIA). Data were pooled from phase I (NCT01513902), phase III (NCT02592434), and open-label, long-term extension (NCT01500551) studies of tofacitinib tablet/solution (weight-based doses administered twice daily [b.i.d.]) in patients with JIA aged 2 to less than 18 years. Population PK modeling used a nonlinear mixed-effects approach, with covariates identified using stepwise forward-inclusion backward-deletion procedures. Simulations were performed to derive dosing recommendations for children and adolescents with JIA. Two hundred forty-six pediatric patients were included in the population PK model. A one-compartment model with first-order elimination and absorption with body weight as a covariate for oral clearance and apparent volume of distribution sufficiently described the data. Oral solution was associated with comparable average concentration (Cavg) and slightly higher (113.9%) maximum concentration (Cmax) versus tablet, which was confirmed by a subsequent randomized, open-label, bioavailability study conducted in healthy adult participants (n = 12) by demonstrating adjusted geometric mean ratios (90% confidence interval) between oral solution and tablet of 1.04 (1.00-1.09) and 1.10 (1.00-1.21) for area under the curve extrapolated to infinity and Cmax, respectively (NCT04111614). A dosing regimen of 3.2 mg b.i.d. solution in patients 10 to less than 20 kg, 4 mg b.i.d. solution in patients 20 to less than 40 kg, and 5 mg b.i.d. tablet/solution in patients greater than or equal to 40 kg, irrespective of age, was proposed to achieve constant Cavg across weight groups. In summary, population PK characterization informed a simplified tofacitinib dosing regimen that has been implemented in pediatric patients with JIA.

The JAK-STAT Signaling Pathway in Epilepsy

Epilepsy is defined as spontaneous recurrent seizures in the brain. There is increasing evidence that inflammatory mediators and immune cells are involved in epileptic seizures. As more research is done on inflammatory factors and immune cells in epilepsy, new targets for the treatment of epilepsy will be revealed. The Janus kinase-signal transducer and transcriptional activator (JAKSTAT) signaling pathway is strongly associated with many immune and inflammatory diseases, At present, more and more studies have found that the JAK-STAT pathway is involved in the development and development of epilepsy, indicating the JAK-STAT pathway's potential promise as a target in epilepsy treatment. In this review, we discuss the composition, activation, and regulation of the JAK-STAT pathway and the relationship between the JAK-STAT pathway and epilepsy. In addition, we summarize the common clinical inhibitors of JAK and STAT that we would expect to be used in epilepsy treatment in the future.

Drug dosing in hospitalized obese patients with COVID-19

Obesity is highly prevalent in hospitalized patients admitted with COVID-19. Evidence based guidelines are available for COVID-19-related therapies but dosing information specific to patients with obesity is lacking. Failure to account for the pharmacokinetic alterations that exist in this population can lead to underdosing, and treatment failure, or overdosing, resulting in an adverse effect. The objective of this manuscript is to provide clinicians with guidance for making dosing decisions for medications used in the treatment of patients with COVID-19. A detailed literature search was conducted for medications listed in evidence-based guidelines from the National Institutes of Health with an emphasis on pharmacokinetics, dosing and obesity. Retrieved manuscripts were evaluated and the following prioritization strategy was used to form the decision framework for recommendations: clinical outcome data > pharmacokinetic studies > adverse effects > physicochemical properties. Most randomized controlled studies included a substantial number of patients who were obese but few had large numbers of patients more extreme forms of obesity. Pharmacokinetic data have described alterations with volume of distribution and clearance but this variability does not appear to warrant dosing modifications. Future studies should provide more information on size descriptors and stratification of data according to obesity and body habitus.

Role of Janus Kinase Inhibitors in Therapy of Psoriasis

Janus kinases inhibitors are molecules that target Janus kinases-signal transducers and activators of transcription (JAK/STAT). They inhibit this intracellular signal pathway, blocking the gene transcription of crucial proinflammatory cytokines that play a central role in the pathogenesis of many inflammatory and autoimmune diseases, including psoriasis. This process reduces psoriatic inflammation. The JAK inhibitors are divided into two generations. The first generation of JAK inhibitors blocks two or more different Janus kinases. The second generation is more specified and blocks only one type of Janus kinase and has less side effects than the first generation. Tofacitinib, ruxolitinib and baricitinib belong to first generation JAK inhibitors and decernotinib and filgotinib belong to second group. This narrative review summarizes the role of Janus kinase inhibitors in the therapy of psoriasis. Oral JAK inhibitors show promise for efficacy and safety in the treatment of psoriasis. Studies to date do not indicate that JAK inhibitors are superior to recent biologic drugs in terms of efficacy. However, JAK inhibitors, due to their lack of increased incidence of side effects compared to other biologic drugs, can be included in the psoriasis treatment algorithm because they are orally taken. Nevertheless, further studies are needed to evaluate long-term treatment effects with these drugs.

Selectivity Profile of the Tyrosine Kinase 2 Inhibitor Deucravacitinib Compared with Janus Kinase 1/2/3 Inhibitors

INTRODUCTION

Deucravacitinib, a novel, oral, selective inhibitor of tyrosine kinase 2 (TYK2) signaling, acts via an allosteric mechanism by binding to the enzyme's regulatory domain instead of the catalytic domain. This unique binding provides high functional selectivity for TYK2 versus the closely related Janus kinases (JAKs) 1/2/3. Deucravacitinib was efficacious in phase 2 and 3 psoriasis trials, without clinical or laboratory parameters indicative of JAK 1/2/3 inhibition being observed. This analysis compared the kinase specificities of deucravacitinib versus JAK 1/2/3 inhibitors at therapeutic exposures.

METHODS

Signaling via JAK 1/3, JAK 2/2, and TYK2/JAK 2 dimers was measured in in vitro whole blood assays. Concentrations providing half-maximal inhibition (IC₅₀) in these assays were determined for deucravacitinib and the JAK 1/2/3 inhibitors tofacitinib, upadacitinib, and baricitinib. Newly derived whole blood IC₅₀ values were plotted against available pharmacokinetic profiles using doses evaluated in phase 2/3 trials. Simulated average daily inhibition and durations over which concentrations exceeded IC₅₀ were evaluated.

RESULTS

At clinically relevant exposures, projected steady-state deucravacitinib plasma concentrations were higher than TYK2 IC₅₀ for approximately 9-18 h. Maximal plasma concentrations (C_max) of deucravacitinib were 8- to 17-fold lower than JAK 1/3 IC₅₀ and > 48- to > 102-fold lower than JAK 2/2 IC₅₀. Simulated daily average TYK2 inhibition by deucravacitinib ranged from 50% to 69%. Simulations indicated that tofacitinib, upadacitinib, and baricitinib at steady state exhibited varying degrees of JAK 1/3 (daily average inhibition, 70-94%) and JAK 2/2 (23%-67%) inhibition at therapeutic concentrations, with C_max values 17- to 33-fold lower than their TYK2 IC₅₀ levels.

CONCLUSION

At clinically relevant doses and exposures, deucravacitinib demonstrates highly selective inhibition of TYK2 and not JAK 1/2/3. Tofacitinib, upadacitinib, and baricitinib variably inhibit JAK 1/2/3 but not TYK2. These results indicate that deucravacitinib is a distinct class of kinase inhibitor compared with JAK 1/2/3 inhibitors.

JAK inhibitors, psoriatic arthritis, and axial spondyloarthritis: a critical review of clinical trials

INTRODUCTION

Psoriatic arthritis (PsA) and spondyloarthritis (SpA) are inflammatory arthritides associated with progressive damage, deformity and morbidity. Janus kinase (JAK) inhibitors block JAKs, cytoplasmic protein tyrosine kinases important in signal transduction and immune processes that are currently being studied as synthetic disease modifying anti-rheumatic drugs (tsDMARDs) in psoriatic arthritis and spondyloarthritis.

AREAS COVERED

This review evaluates published phase 2 and 3 clinical trial data for JAK kinase inhibitors for psoriatic arthritis and spondyloarthritis. A literature search using PubMed was conducted using the following keywords: 'psoriatic arthritis', 'ankylosing spondylitis', 'axial spondyloarthritis', 'non-radiographic axial spondyloarthritis', 'tofacitinib', 'baricitinib', 'filgotinib' and 'upadacitinib'. Mechanism of action, phase 2 and 3 clinical trial data, including efficacy and safety, are discussed.

EXPERT OPINION

JAK inhibitors are important orally administered agents conferring different degrees of selectivity toward JAK1, JAK2, and JAK3 which may have implications on efficacy and safety in PsA and SpA. Phase 2 and 3 clinical trials in PsA for tofacitinib and upadacitinib and phase 2 for filgotinib confirmed efficacy comparable to biologic DMARDs. In SpA, phase 2 and 2/3 studies confirmed significant efficacy of tofacitinib, filgotinib and upadacitinib compared to placebo. Safety was comparable to clinical trial, long-term extension, and registry data for rheumatoid arthritis.

Identification of the metabolites of tofacitinib in liver microsomes by liquid chromatography combined with high resolution mass spectrometry

Tofacitinib is an orally available Janus kinase inhibitor. The aim of this study was to investigate the metabolism of tofacitinib in mouse, rat, monkey, and human liver microsomes fortified with β-nicotinamide adenine dinucleotide phosphate tetrasodium salt and uridine diphosphate glucuronic acid. The biotransformation was executed at a temperature of 37°C for 60 min, and the samples were analyzed by ultra-high performance liquid chromatography combined with high-resolution mass spectrometry (UHPLC-HRMS) operated in positive electrospray ionization mode. The structures of the metabolites were elucidated according to their retention times, accurate masses, and MS/MS spectra. Under the current conditions, a total of 13 metabolites, including 1 glucuronide conjugate, were detected and structurally proposed. Oxygenation of the pyrrolopyrimidine ring, oxygenation of piperidine ring, N-demethylation, oxygenation of piperidine ring side chain, and glucuronidation were the primary metabolic pathways of tofacitinib. Among the tested species, tofacitinib showed significant species difference. Compared with other species, rat showed similar metabolic profiles to those of humans. The present study provides some new information regarding the metabolism of tofacitinib in animals and humans, which would bring us considerable benefits for the subsequent studies focusing on the pharmacological effect and toxicity of this drug.

Population Pharmacokinetics of Tofacitinib in Patients With Moderate to Severe Ulcerative Colitis

Tofacitinib is an oral, small molecule Janus kinase inhibitor for the treatment of ulcerative colitis (UC). We characterized tofacitinib pharmacokinetics in patients with moderate to severe UC, and the effects of covariates on variability in pharmacokinetic parameter estimates. Data were pooled from 1 8‐week phase 2 and 2 8‐week phase 3 induction studies, and a 52‐week phase 3 maintenance study (N = 1096). Population pharmacokinetic analysis was conducted using nonlinear mixed‐effects modeling. Potential predictors of apparent oral clearance (CL/F) and volume of distribution (V/F) were evaluated. The PK was described by a 1‐compartment model parameterized in terms of CL/F (26.3 L/hour [h]) and V/F (115.8 L), with first‐order absorption (K_a; 9.85 h⁻¹) and lag time (0.236 h). The derived elimination half‐life was approximately 3.05 h. In the final model, baseline creatinine clearance, sex, and race (Asian vs non‐Asian) were significant covariates for CL/F; significant covariates for V/F were age, sex, and body weight; baseline albumin and baseline Mayo score were not significant covariates. CL/F between‐patient variability was estimated at 22%. Tofacitinib exposure did not change significantly over the duration of induction/maintenance treatment in patients with UC. Although statistically significant covariate effects on CL/F and V/F were observed, the magnitude of the effects are not clinically significant. Therefore, dose adjustment/restrictions for age, body weight, sex, race, or baseline disease severity are not required during tofacitinib treatment. ClinicalTrials.gov numbers: NCT00787202, NCT01465763, NCT01458951, NCT01458574.

Sex differences in disease activity and efficacy of treatment in spondyloarthritis: is body composition the cause?

PURPOSE OF REVIEW

The body composition and fat distribution is different between men and women, with different levels of circulating adipokines. These differences become more evident when suffering from an inflammatory disease, such as spondyloarthritris. In this review, we will explore the influence of obesity, body composition and adipokines on the differences in disease activity, progression and response to treatment, between men and women with spondyloarthritis.

RECENT FINDINGS

Obesity, mainly determined by the body fat content, which is higher in women, is related to worse disease activity scores. Men with higher disease activity lose more muscle mass than women. Leptin, which is usually found at higher levels in overweight women, seems to be associated with greater spinal radiographic progression when it rises during the course of the disease. Being a woman and obesity, mainly because of the body fat content, are related to a worse response to TNF-α blockers.

SUMMARY

Overlooking biological sex variation in body composition, circulating adipokines and hormonal levels, and the subsequent differences in clinical presentation, may ultimately hamper clinical treatment.