Upadacitinib pharmacokinetics and exposure-response analyses of efficacy and safety in psoriatic arthritis patients - Analyses of phase III clinical trials

Pharmacokinetics, Efficacy, and Safety of Upadacitinib in Pediatric Patients With Polyarticular-Course Juvenile Idiopathic Arthritis: An Interim Analysis of an Open-Label, Phase 1 Trial

OBJECTIVE

This work aimed to evaluate the pharmacokinetics, efficacy, and safety of upadacitinib, an oral selective JAK inhibitor, in pediatric patients with polyarticular-course juvenile idiopathic arthritis (pcJIA).

METHODS

In an open-label, phase 1 study (SELECT-YOUTH), enrolled patients, aged 2 to <18 years with pcJIA, received body weight-based upadacitinib doses using a twice-daily oral solution or once-daily extended-release tablet based on their body weight and ability to swallow tablets. The study included a 7-day pharmacokinetic assessment, followed by a long-term efficacy and safety evaluation for up to 156 weeks, including an additional long-term safety cohort. This interim analysis included available pharmacokinetic and safety data and efficacy data collected through week 48.

RESULTS

A total of 57 patients received upadacitinib. The median time to maximum upadacitinib concentration was approximately three hours and one hour for the tablet and oral solution regimens, respectively; the harmonic mean functional half-life was approximately five hours and two hours, respectively. Juvenile idiopathic arthritis American College of Rheumatology 30, 50, 70, 90, and 100 responses at week 12 were 91.8%, 89.8%, 69.4%, 49.0%, and 32.7%, respectively. Efficacy was generally maintained through week 48, and improvement in additional efficacy end points was also observed. At a median exposure duration of 412 days, 52 of 57 patients reported adverse events; of these, 6 experienced serious adverse events. Adverse events were predominately mild to moderate in severity and consistent with the known safety profile of upadacitinib.

CONCLUSION

This interim analysis demonstrates that the bodyweight-based dosing regimen of upadacitinib was well tolerated and efficacious in pediatric patients with pcJIA.

Kupffer Cell-derived IL6 Promotes Hepatocellular Carcinoma Metastasis Via the JAK1-ACAP4 Pathway

Tumor-associated macrophages (TAMs), which differentiate from tissue-resident macrophages, are recognized for their ability to influence cancer progression and metastasis. However, the specific role of Kupffer cells (KCs), the intrinsic macrophages of the liver, in the progression of hepatocellular carcinoma (HCC) remains unclear. In this study, we describe a novel mechanism by which exosomes derived from HCC cells induce KCs to transition into TAMs, thereby facilitating the metastasis of HCC in an IL6-JAK1-ACAP4 axis-dependent manner. Mechanistically, the exosome-mediated domestication of KCs by hepatoma cells constitutes one of the primary sources of IL6 production in the HCC microenvironment. IL6 then activates JAK1 to phosphorylate its downstream effector ACAP4 at Tyr843, a novel phosphorylation site identified in this context, which in turn promotes ARF6-GTPase activity and hepatoma cell migration. Furthermore, we found that the levels of IL6, as well as the phosphorylation of JAK1 and ACAP4 at Tyr843, were significantly greater in tumor tissues from HCC patients than in adjacent tissues. These findings suggest that the IL6-JAK1-ACAP4 axis may be a promising therapeutic target for HCC. Importantly, we screened bufalin, an active ingredient derived from Venenum Bufonis, and discovered that it inhibits JAK1 and disrupts the IL6-induced phosphorylation of ACAP4. This inhibition not only impairs hepatoma cell migration but also prevents the metastasis of HCC. These findings demonstrate the interplay between hepatoma cells and KCs through the IL6-JAK1-ACAP4 axis, thereby promoting HCC metastasis, and reveal the therapeutic potential of bufalin for the treatment of HCC through JAK1 inhibition.

Medicinal chemistry perspective of JAK inhibitors: synthesis, biological profile, selectivity, and structure activity relationship

JAK-STAT signalling pathway was discovered more than quarter century ago. The JAK-STAT pathway protein is considered as one of the crucial hubs for cytokine secretion which mediates activation of different inflammatory, cellular responses and hence involved in different etiological factors. The various etiological factors involved are haematopoiesis, immune fitness, tissue repair, inflammation, apoptosis, and adipogenesis. The presence of the active mutation V617K plays a significant role in the progression of the JAK-STAT pathway-related disease. Consequently, targeting the JAK-STAT pathway could be a promising therapeutic approach for addressing a range of causative factors. In this current review, we provided a comprehensive discussion for the in-detail study of anatomy and physiology of the JAK-STAT pathway which contributes structural domain rearrangement, activation, and negative regulation associated with the downstream signaling pathway, relationship between different cytokines and diseases. This review also discussed the recent development of clinical trial entities. Additionally, this review also provides updates on FDA-approved drugs. In the current investigation, we have classified recently developed small molecule inhibitors of JAK-STAT pathway according to different chemical classes and we emphasized their synthetic routes, biological evaluation, selectivity, and structure-activity relationship.

Extrapolation of Upadacitinib Efficacy in Juvenile Idiopathic Arthritis Leveraging Pharmacokinetics, Exposure-Response Models, and Real-World Patient Data

Juvenile idiopathic arthritis (JIA) is the most prevalent pediatric rheumatic disease. While disease-modifying antirheumatic drugs (DMARDs), especially biologics, have greatly transformed the management of JIA, there remain some unmet medical needs that require new treatment options. The objective of this work was to describe and apply a modeling and simulation approach to extrapolate upadacitinib efficacy from the adult diseases, rheumatoid arthritis (RA) and psoriatic arthritis (PsA), to their respective pediatric diseases, polyarticular course JIA (pcJIA), and juvenile PsA (JPsA). A population pharmacokinetic model characterized upadacitinib pharmacokinetics in pediatric patients using data from two phase I studies in pediatric patients with pcJIA (N = 51) or atopic dermatitis (N = 33). Efficacy simulations were conducted using previously developed exposure-response models in adults with RA and PsA. Real-world pcJIA and JPsA patient databases were leveraged to construct representative patient profiles for the targeted population. Following administration of the proposed weight-based dosing regimen, the model-predicted median upadacitinib plasma exposures in pediatric patients were within 20% of those in adult RA and PsA patients receiving the approved adult regimen. Simulations demonstrate that upadacitinib efficacy in pcJIA and JPsA is predicted to be non-inferior to that in adults with RA or PsA, respectively. The results of this work enabled recent approvals of upadacitinib for the treatment of polyarticular JIA and JPsA in the United States. Upadacitinib safety in pediatrics is being further evaluated in ongoing clinical trials.

Pharmacokinetics and Exposure-Response Analyses to Support Dose Selection of Upadacitinib in Crohn's Disease

Upadacitinib, a selective Janus kinase inhibitor, is the first orally administered therapy approved for the treatment of Crohn's disease (CD). This work characterized the pharmacokinetics of upadacitinib in CD patients and evaluated the relationships between upadacitinib steady-state plasma exposures and efficacy as well as safety parameters during the 12-week induction and the 52-week maintenance periods, to provide dosing recommendations for the treatment of CD. Upadacitinib pharmacokinetics in CD patients administered the extended-release formulation were consistent with patient populations in other approved indications. None of the evaluated CD-specific patient characteristics (e.g., disease location and prior gastrointestinal surgeries) had a meaningful impact on upadacitinib pharmacokinetics. Exposure-response analyses during 12-week induction treatment showed that response across all evaluated efficacy end points were approaching a plateau at median plasma exposures associated with 45 mg QD. Analyses for the maintenance period demonstrated that 30 mg QD is predicted to provide an additional 8% to 10% benefit for endoscopic response and endoscopic remission compared with 15 mg QD in patients who failed biologics. The analyses for safety showed a statistically significant relationship between increasing upadacitinib plasma exposures and the percentage of patients experiencing >2 g/dL decrease in hemoglobin from Baseline during induction and showed shallow relationships for serious infections and herpes zoster during the maintenance period. These results demonstrated adequate absorption of the extended-release formulation of upadacitinib in CD patients. The exposure-response analyses confirmed that 45 mg QD dose maximized efficacy as induction treatment and supported the selection of 15 mg QD or 30 mg QD as the maintenance doses.

Therapeutic inhibition of the JAK-STAT pathway in the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) encompasses a group of non-specific chronic intestinal inflammatory conditions of unclear etiology. The current treatment and long-term management primarily involve biologics. Nevertheless, some patients experience treatment failure or intolerance to biologics [1], making these patients a primary focus of IBD research. The Janus kinase (JAK)-Signal Transducers and Activator of Transcription (STAT) signal transduction pathway is crucial to the regulation of immune and inflammatory responses [2], and plays an important role in the pathogenesis of IBD. JAK inhibitors alleviate IBD by suppressing the transmission of JAK-STAT signaling pathway. As the first small-molecule oral inhibitor for IBD, JAK inhibitors greatly improved the treatment of IBD and have demonstrated significant efficacy, with tofacitinib and upadacitinib being approved for the treatment of ulcerative colitis (UC) [3]. JAK inhibitors can effectively alleviate intestinal inflammation in IBD patients who have failed to receive biologics, which may bring new treatment opportunities for refractory IBD patients. This review aims to elucidate the crucial roles of JAK-STAT signal transduction pathway in IBD pathogenesis, examine its role in various cell types within IBD, and explore the research progress of JAK inhibitors as therapeutic agents, paving the road for new IBD treatment strategies.

FDA-Approved Janus Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) Inhibitors for Managing Rheumatoid Arthritis: A Narrative Review of the Literature

Rheumatoid arthritis (RA) is a complex autoimmune disease causing chronic joint inflammation and, in more serious cases, organ involvement. RA typically affects people between the ages of 35 and 60; however, it can also afflict children younger than the age of 16 years and can also demonstrate a pattern of remission later in the disease course. Non-steroidal anti-inflammatory drugs, glucocorticoids, exercise, and patient education are all used in the management of RA, which is divided into symptomatic management and disease-modifying management (disease-modifying antirheumatic drugs) to reduce pain and inflammation, thereby preserving joint function. Janus kinase inhibitors (JAKis) have led to a substantial improvement in the management of RA. By specifically targeting the JAK-signal transducer and activator of transcription pathway, which is essential for immunological modulation, these inhibitors also demonstrate promise in treating various autoimmune illnesses, including inflammatory bowel diseases, giant cell arteritis, ankylosing spondylitis, and psoriatic arthritis. Tofacitinib, baricitinib, upadacitinib, peficitinib, delgocitinib, and filgotinib are examples of FDA-approved JAKis that have distinct properties and indications for treating a range of autoimmune illnesses. JAKis demonstrate a promising treatment approach for managing RA and other autoimmune diseases while enhancing patient outcomes and quality of life. However, due to major safety concerns and the need for long-term success, meticulous patient monitoring is essential.

Upadacitinib for the treatment of adult patients with active psoriatic arthritis

INTRODUCTION

Psoriatic arthritis (PsA) is a rheumatic disorder that may be responsible for relevant articular impairment. The recently licensed Janus Kinase (JaK) inhibitors represent a new opportunity to improve PsA treatment. This review deals with the clinical usefulness of the selective JaK-1 inhibitor upadacitinib (UPA) in patients with PsA.

COVERED AREAS

Two phase-III studies are available: SELECT-PsA 1, performed in patients with an inadequate response to non-biological therapies, and SELECT-PsA 2, conducted in biologic-experienced patients. Long-term extension results and post-hoc analysis data of these two trials are also available.

EXPERT OPINION

The results provided by the trials indicate that UPA may be used to treat all of the clinical manifestations of PsA. Venous thromboembolism, cardiovascular events, and malignancy, the most feared adverse events associated with JaK inhibitor use, were not increased in the trial populations, yet long-term observational studies are needed to make sure that UPA is safe in this respect.

Evaluating the pharmacokinetics of upadacitinib for the treatment of moderate-to-severe Crohn's disease

INTRODUCTION

Janus kinases (JAK) are enzymes involved in signaling pathways that activate the immune system. Upadacitinib, an oral small molecule, is the first JAK inhibitor approved by FDA and EMA for the treatment of moderately to severely active Crohn's disease (CD), following successful phase II and III trials. Compared to other JAK inhibitors, upadacitinib has a high selectivity toward JAK1. This characteristic could improve its efficacy and safety.

AREAS COVERED

This review provides an overview of the available knowledge on the pharmacokinetics of upadacitinib as induction and maintenance therapy for CD.

EXPERT OPINION

The approval of newer targeted small molecules drug, including JAK inhibitors, marked a significant advancement in terms of effectiveness. In fact, the oral administration, the rapid absorption, the excellent bioavailability and the short serum time of maximum concentration are some of the advantages compared to biologics. The selective inhibition of JAK1 by upadacitinib allows for high efficacy while maintaining a reliable safety profile.

Population pharmacokinetics and exposure-response analyses for efficacy and safety of upadacitinib in patients with axial spondyloarthritis

Upadacitinib is an orally administered, selective, Janus kinase inhibitor that is approved for several auto-immune conditions, such as axial spondyloarthritis, an inflammatory rheumatic disease that includes ankylosing spondylitis (AS) and non-radiographic axial spondyloarthritis (nr-axSpA). The approvals of upadacitinib for the treatment of AS and nr-axSpA were based on the safety and efficacy data for upadacitinib 15 mg once-daily compared to placebo from the SELECT-AXIS 1 and SELECT-AXIS 2 studies. Population pharmacokinetic analyses based on data from 244 patients with axSpA showed that the pharmacokinetics of upadacitinib were comparable in subjects with AS and nr-axSpA. Exposure-response relationships were characterized for key efficacy and safety end points using data from 482 patients with axSpA. The exposure-response analyses for efficacy based on Assessment of SpondyloArthritis International Society (ASAS)20 and ASAS40 responses at week 14, showed a clear differentiation from placebo with no evidence of increased responses with increasing upadacitinib plasma exposures. There were no clear exposure-response trends observed for safety end points that included serious infections, herpes zoster, pneumonia, lymphopenia (grade ≥3), neutropenia (grade ≥3), or a greater than 2 g/dL decrease in hemoglobin from baseline through week 14. The exposure-response analyses for efficacy and safety presented here supported the favorable benefit-risk profile with the use of upadacitinib 15 mg once-daily for the treatment of axSpA.

Differential properties of Janus kinase inhibitors in the treatment of immune-mediated inflammatory diseases

Janus kinases (JAKs) are a family of cytosolic tyrosine kinases that regulate cytokine signal transduction, including cytokines involved in a range of inflammatory diseases, such as RA, psoriasis, atopic dermatitis and IBD. Several small-molecule JAK inhibitors (JAKis) are now approved for the treatment of various immune-mediated inflammatory diseases. There are, however, key differences between these agents that could potentially translate into unique clinical profiles. Each JAKi has a unique chemical structure, resulting in a distinctive mode of binding within the catalytic cleft of the target JAK, and giving rise to distinct pharmacological characteristics. In addition, the available agents have differing selectivity for JAK isoforms, as well as off-target effects against non-JAKs. Other differences include effects on haematological parameters, DNA damage repair, reproductive toxicity and metabolism/elimination. Here we review the pharmacological profiles of the JAKis abrocitinib, baricitinib, filgotinib, peficitinib, tofacitinib and upadacitinib.

Therapeutic Drug Monitoring for Biologic and Small-Molecule Therapies for Inflammatory Bowel Disease

Background: Inflammatory bowel disease (IBD), encompassing ulcerative colitis and Crohn's disease, necessitates long-term medical therapy to manage symptoms and prevent complications. Therapeutic drug monitoring (TDM) has emerged as a strategy to optimize treatment efficacy, particularly with anti-tumour necrosis factor (anti-TNF) alpha drugs. This review explores the role of TDM for non-anti-TNF advanced therapies in IBD, focusing on vedolizumab, ustekinumab, tofacitinib, upadacitinib, risankizumab and ozanimod. Methods: The literature search, conducted through OVID (Medline) and PubMed, delves into proactive versus reactive TDM, timing of monitoring and methods for measuring drug levels and anti-drug antibodies. Results: While ustekinumab and vedolizumab exhibit exposure-response relationships, consensus on target levels and the role of TDM adjustments remains elusive. Limited data on risankizumab suggest a dose-dependent response, while for small molecule therapies (janus kinase inhibitors and ozanimod), the absence of real-world data and commercially available TDM tools pose challenges. Conclusion: At present, with the available data, there is a limited role for TDM in non-anti-TNF biologic and small-molecule therapies. This review underscores the need for further research to delineate the utility of TDM in guiding treatment decisions for these agents.

Potential applications of JAK inhibitors, clinically approved drugs against autoimmune diseases, in cancer therapy

Disturbances in immunoregulation may lead to both cancer and autoimmune diseases. Many therapeutic drugs for autoimmune diseases also display anti-tumor efficacy. The Janus kinase/signal transducer and activator of transcription signaling pathways are involved in the secretion of more than 50 distinct cytokines, which have critical roles in inducing autoimmune diseases and tumorigenesis. Thus, Janus kinases have become classical immunotherapeutic targets for immune disease. More than 70 Janus kinase inhibitors have been approved as immunomodulatory drugs for clinical use, of which 12 are used in the treatment of autoimmune diseases. This systematic review aims to elucidate the anti-tumor role of clinically approved Janus kinase inhibitors that were primarily designed for the treatment of autoimmune diseases and their potential for clinical translation as cancer treatments.

Upadacitinib: Mechanism of action, clinical, and translational science

Upadacitinib is a selective Janus kinase (JAK) inhibitor which is approved by the US Food and Drug Administration, the European Medicines Agency, as well as other agencies around the world for the treatment of several chronic inflammatory diseases, including rheumatic, dermatologic, and gastrointestinal diseases. Through inhibition of JAK, upadacitinib inhibits phosphorylation of downstream effector proteins, which consequently inhibits cytokine signaling for key pathways involved in inflammatory diseases. Upadacitinib more potently inhibits JAK1 than other JAK isoforms. The pharmacokinetics, pharmacodynamics, efficacy, and safety of upadacitinib were characterized in many clinical trials, which demonstrated the superiority of upadacitinib treatment over placebo or an active comparator in rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, non-radiographic axial spondyloarthritis, atopic dermatitis, Crohn's disease, and ulcerative colitis. The safety profile of upadacitinib supported a favorable benefit-risk profile across all the approved indications. In this article, we review the mechanism of action of upadacitinib and describe how the JAK-STAT (Janus kinase-signal transducers and activators of transcription) pathway is involved in the pathogenesis of several chronic and progressive immune-mediated inflammatory diseases. In addition, this review also provides an overview of key clinical trials that were conducted as well as relevant data which supported the clinical development of upadacitinib and informed the recommended dose(s) in each of the approved indications.

Development and validation of a multiplex HPLC-MS/MS assay for the monitoring of JAK inhibitors in patient plasma

Janus kinase inhibitors (JAKi) are oral small molecules used in the treatment of a broad spectrum of autoimmune and myeloproliferative diseases. JAKi exhibit significant intra- and inter-individual pharmacokinetic variabilities, due to fluctuations in compliance with oral treatments and their metabolism essentially driven by cytochrome P450 enzymes. Intrinsically, JAKi have dose-response relationship and narrow therapeutic index: therapeutic drug monitoring (TDM) is expected to optimize and adapt their dosage regimen in order to resolve problems of efficacy and tolerance linked to dose and safety. A sensitive analytical method using multiplex high-performance liquid-chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) was developed and validated for the simultaneous quantification in plasma of the 6 major currently used JAKi, namely abrocitinib, baricitinib, fedratinib, ruxolitinib, tofacitinib, and upadacitinib. Plasma samples are subjected to protein precipitation with MeOH, using stable isotopically labelled internal standards. The separation of JAKi in supernatants diluted 1:1 with ultrapure H2O was performed using a C18 column Xselect HSS T3 2.5 µm, 2.1x150 mm using a mobile phase composed of formic acid (FA) 0.2% and acetonitrile (+FA 0.1%) in gradient mode. The analytical run time for the multiplex assay was 7 min. JAKi drugs were monitored by electrospray ionization in the positive mode followed by triple-stage quadrupole MS/MS analysis. The method was validated according to SFSTP and ICH guidelines over the clinically relevant concentration ranges (0.5-200 ng/mL for abrocitinib, baricitinib and upadacitinib; 1-400 ng/mL for tofacitinib; 0.5-400 ng/mL for ruxolitinib, and 10-800 ng/mL for fedratinib). This multiplex HPLC-MS/MS assay achieved good performances in term of trueness (91.1-113.5%), repeatability (3.0-9.9%), and intermediate precision (4.5-11.3%). We developed and validated a highly sensitive method for the multiplex quantification of the JAKi abrocitinib, baricitinib, fedratinib, ruxolitinib, tofacitinib, and upadacitinib in human plasma. The method will be applied for prospective clinical pharmacokinetic studies to determine whether TDM programs for JAKi based on residual drug concentrations can be recommended using disease-specific therapeutic ranges.

SOCS-JAK-STAT inhibitors and SOCS mimetics as treatment options for autoimmune uveitis, psoriasis, lupus, and autoimmune encephalitis

Autoimmune diseases arise from atypical immune responses that attack self-tissue epitopes, and their development is intricately connected to the disruption of the JAK-STAT signaling pathway, where SOCS proteins play crucial roles. Conditions such as autoimmune uveitis, psoriasis, lupus, and autoimmune encephalitis exhibit immune system dysfunctions associated with JAK-STAT signaling dysregulation. Emerging therapeutic strategies utilize JAK-STAT inhibitors and SOCS mimetics to modulate immune responses and alleviate autoimmune manifestations. Although more research and clinical studies are required to assess their effectiveness, safety profiles, and potential for personalized therapeutic approaches in autoimmune conditions, JAK-STAT inhibitors and SOCS mimetics show promise as potential treatment options. This review explores the action, effectiveness, safety profiles, and future prospects of JAK inhibitors and SOCS mimetics as therapeutic agents for psoriasis, autoimmune uveitis, systemic lupus erythematosus, and autoimmune encephalitis. The findings underscore the importance of investigating these targeted therapies to advance treatment options for individuals suffering from autoimmune diseases.

Inflammatory Cytokines in Psoriatic Arthritis: Understanding Pathogenesis and Implications for Treatment

Psoriatic arthritis (PsA) is a persistent, inflammatory disease that affects individuals with psoriasis, arthritis, and enthesitis. Research has demonstrated that inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-23 (IL-23), and interleukin-17 (IL-17) play a pivotal role in both the onset and progression of PsA. These cytokines are generated by activated immune cells and stimulate the attraction of inflammatory cells to the synovium and joint tissues, resulting in the deterioration of cartilage and bone. The blocking of these cytokines has become a successful treatment strategy for PsA, as biological drugs that inhibit TNF-α, IL-23, and IL-17 have demonstrated notable clinical benefits. The association between PsA and other types of inflammatory cytokines or chemokines, excluding TNF-α, IL-23, and IL-17, has been extensively investigated in numerous studies. These findings may provide a chance for the discovery of novel therapeutic agents targeting other molecules, distinct from the currently approved biologics and targeted synthetic disease-modifying anti-rheumatic drugs. In this review, we discuss the current understanding of the role of inflammatory cytokines in PsA pathogenesis and clinical implications of targeting these cytokines for PsA treatment.

Post-Marketing Safety Concerns with Upadacitinib: A Disproportionality Analysis of the FDA Adverse Event Reporting system

BACKGROUND

Upadacitinib was approved to treat rheumatoid arthritis, psoriasis, ulcerative colitis, ankylosing spondylitis, and atopic dermatitis. This study assessed the adverse events (AEs) associated with upadacitinib by mining data from the US Food and Drug Administration Adverse Event Reporting System (FAERS).

METHODS

Disproportionality analyses, including the reporting odds ratio (ROR), the proportional reporting ratio (PRR), the Bayesian confidence propagation neural network (BCPNN), and the multi-item gamma Poisson shrinker (MGPS) algorithms, were employed to quantify the signals of upadacitinib-associated AEs.

RESULTS

A total of 3,837,420 reports of AEs were collected from the FAERS database, of which 4494 reports were identified with upadacitinib as the "primary suspect (PS)". Upadacitinib-induced AEs occurrence targeted 27 system organ clases (SOCs). A total of 200 significant disproportionality PTs conforming to the four algorithms were simultaneously retained. Unexpected significant AEs, such as arthralgia, musculoskeletal stiffness, diverticulitis, and cataract might also occur. The median onset time of upadacitinib-associated AEs was 65 days (interquartile range [IQR] 21-182 days), and most of the onsets occurred within the first 1, 2, 3, and 4 months after initiation of upadacitinib.

CONCLUSION

This study found potential new AEs signals and might provide important support for clinical monitoring and risk identification of upadacitinib.

Upadacitinib Population Pharmacokinetics and Exposure-Response Relationships in Ulcerative Colitis Patients

BACKGROUND AND OBJECTIVE

Upadacitinib, an oral selective and reversible Janus kinase (JAK) inhibitor, showed favorable efficacy and safety in patients with moderate-to-severe ulcerative colitis (UC). The objective was to characterize upadacitinib pharmacokinetics in UC patients across Phase 2b and 3 trials and evaluate the relationships between upadacitinib plasma exposures and key efficacy or safety endpoints.

METHODS

Population pharmacokinetics and exposure-response analyses were performed to characterize upadacitinib pharmacokinetics in UC patients and evaluate the relationships between plasma exposures and key efficacy or safety endpoints at the end of 8-week induction and 52-week maintenance periods. Data from 1234 UC patients from Phase 2 and 3 induction trials and 449 UC patients from a Phase 3 maintenance trial were used for these analyses. Additionally, data from patients with rheumatoid arthritis, atopic dermatitis, Crohn's disease, and healthy volunteers were used in the pharmacokinetics analysis. Quartile plots and logistic regression models were used to evaluate the exposure-response relationships across upadacitinib doses of 7.5-45 mg once daily (QD) for induction and 15-30 mg QD for maintenance.

RESULTS

Upadacitinib plasma exposures were dose-proportional in UC patients across the evaluated dose range. Upadacitinib pharmacokinetics in UC were consistent between the induction and maintenance periods, and with other patient populations. Upadacitinib plasma exposures associated with the 45 mg QD induction dose maximized efficacy for Week 8 clinical and endoscopic endpoints. Plasma exposures associated with upadacitinib 30 mg maintenance dose provided additional incremental benefit compared to 15 mg QD for Week 52 key clinical and endoscopic endpoints. No trends were observed in the evaluated safety events with increasing plasma exposures at the end of induction or maintenance periods.

CONCLUSION

These analyses supported selection of upadacitinib UC induction and maintenance doses.

TRIAL REGISTRATION

Data from studies NCT02819635 and NCT03653026 were included in these analyses.

Molecular dissection of Janus kinases as drug targets for inflammatory diseases

The Janus kinase (JAK) family enzymes are non-receptor tyrosine kinases that phosphorylate cytokine receptors and signal transducer and activator of transcription (STAT) proteins in the JAK-STAT signaling pathway. Considering that JAK-STAT signal transduction is initiated by the binding of ligands, such as cytokines to their receptors, dysfunctional JAKs in the JAK-STAT pathway can lead to severe immune system-related diseases, including autoimmune disorders. Therefore, JAKs are attractive drug targets to develop therapies that block abnormal JAK-STAT signaling. To date, various JAK inhibitors have been developed to block cytokine-triggered signaling pathways. However, kinase inhibitors have intrinsic limitations to drug selectivity. Moreover, resistance to the developed JAK inhibitors constitutes a recently emerging issue owing to the occurrence of drug-resistant mutations. In this review, we discuss the role of JAKs in the JAK-STAT signaling pathway and analyze the structures of JAKs, along with their conformational changes for catalysis. In addition, the entire structure of the murine JAK1 elucidated recently provides information on an interaction mode for dimerization. Based on updated structural information on JAKs, we also discuss strategies for disrupting the dimerization of JAKs to develop novel JAK inhibitors.

What's new and what's next for biological and targeted synthetic treatments in psoriatic arthritis?

INTRODUCTION

Psoriatic arthritis (PsA) is a chronic arthritis typically associated with cutaneous psoriasis (PsO). Its pathogenesis is connected to an innate and acquired immune response, as well as genetic risk alleles. The extent of immunopathogenic mechanisms and the heterogenicity of clinical manifestation make the identification of patient-targeted therapies a critical issue, and the treatment decision challenging in patients' management.

AREAS COVERED

This review includes a brief overview of biological and small-molecule therapies, focusing on evidence from clinical trials and real-world data that support their use in PsA. We summarize novel and future possible therapeutic strategies, the importance that comorbidities have on selection of therapy and discuss the adverse event of each drug. Relevant papers for up to 1 August 2022 (trials, real-life studies, and reviews) regarding biologics and/or small molecules were summarized.

EXPERT OPINION

In recent years, the treatment of PsA has been revolutionized by new targeted therapies, which offer the opportunity to perform a tailored-tail management, considering risk factors, comorbidities, and the different PsA phenotypes. Growing experience with these new agents allows novel treatment approaches that may improve clinical outcomes for PsA patients, in terms of remission/low disease activity and quality of life.

Janus kinase (JAK) inhibitors in the treatment of neoplastic and inflammatory disorders

The Janus kinase (JAK) family of nonreceptor protein-tyrosine kinases consists of JAK1, JAK2, JAK3, and TYK2 (Tyrosine Kinase 2). Each of these proteins contains a JAK homology pseudokinase (JH2) domain that interacts with and regulates the activity of the adjacent protein kinase domain (JH1). The Janus kinase family is regulated by numerous cytokines including interferons, interleukins, and hormones such as erythropoietin and thrombopoietin. Ligand binding to cytokine receptors leads to the activation of associated Janus kinases, which then catalyze the phosphorylation of the receptors. The SH2 domain of signal transducers and activators of transcription (STAT) binds to the cytokine receptor phosphotyrosines thereby promoting STAT phosphorylation and activation by the Janus kinases. STAT dimers are then translocated into the nucleus where they participate in the regulation and expression of dozens of proteins. JAK1/3 signaling participates in the pathogenesis of inflammatory disorders while JAK1/2 signaling contributes to the development of myeloproliferative neoplasms as well as several malignancies including leukemias and lymphomas. An activating JAK2 V617F mutation occurs in 95% of people with polycythemia vera and about 50% of cases of myelofibrosis and essential thrombocythemia. Abrocitinib, ruxolitinib, and upadacitinib are JAK inhibitors that are FDA-approved for the treatment of atopic dermatitis. Baricitinib is used for the treatment of rheumatoid arthritis and covid 19. Tofacitinib and upadacitinib are JAK antagonists that are used for the treatment of rheumatoid arthritis and ulcerative colitis. Additionally, ruxolitinib is approved for the treatment of polycythemia vera while fedratinib, pacritinib, and ruxolitinib are approved for the treatment of myelofibrosis.

A Comprehensive Overview of Globally Approved JAK Inhibitors

Janus kinase (JAK) is a family of cytoplasmic non-receptor tyrosine kinases that includes four members, namely JAK1, JAK2, JAK3, and TYK2. The JAKs transduce cytokine signaling through the JAK-STAT pathway, which regulates the transcription of several genes involved in inflammatory, immune, and cancer conditions. Targeting the JAK family kinases with small-molecule inhibitors has proved to be effective in the treatment of different types of diseases. In the current review, eleven of the JAK inhibitors that received approval for clinical use have been discussed. These drugs are abrocitinib, baricitinib, delgocitinib, fedratinib, filgotinib, oclacitinib, pacritinib, peficitinib, ruxolitinib, tofacitinib, and upadacitinib. The aim of the current review was to provide an integrated overview of the chemical and pharmacological data of the globally approved JAK inhibitors. The synthetic routes of the eleven drugs were described. In addition, their inhibitory activities against different kinases and their pharmacological uses have also been explained. Moreover, their crystal structures with different kinases were summarized, with a primary focus on their binding modes and interactions. The proposed metabolic pathways and metabolites of these drugs were also illustrated. To sum up, the data in the current review could help in the design of new JAK inhibitors with potential therapeutic benefits in inflammatory and autoimmune diseases.