A JAK Inhibitor for Treatment of Rheumatoid Arthritis: The Baricitinib Experience

Rheumatic adverse events of immune checkpoint inhibitors in cancer immunotherapy

INTRODUCTION

The advent of immune checkpoint inhibitors (ICIs) in cancer treatment has marked a transformative era, albeit tempered by immune-related adverse events (irAEs), including those impacting the musculoskeletal system. The lack of precise epidemiologic data on rheumatic irAEs is attributed to factors such as potential underrecognition, underreporting in clinical trials, and the tendency to overlook manifestations without immediate life-threatening implications, further complicating the determination of accurate incidence rates, while the complete understanding of the mechanisms driving rheumatic irAEs remains elusive.

AREAS COVERED

This literature review comprehensively examines rheumatic irAEs in cancer patients undergoing ICI therapy, encompassing epidemiology, risk factors, mechanisms, clinical manifestations, and current management guidance for prevalent conditions such as inflammatory arthritis, polymyalgia rheumatica, and myositis. Less frequent rheumatic and musculoskeletal irAEs are also explored, alongside insights into ongoing clinical trials testing therapeutic and preventive strategies for irAEs. A thorough literature search on Medline and the National Cancer Institute Clinical Trials Database was conducted up to October 2023 to compile relevant information.

EXPERT OPINION

In light of the evolving landscape of cancer immunotherapy, there is a compelling need for prospective longitudinal studies to enhance understanding and inform clinical management strategies for rheumatic irAEs.

Pharmacokinetic review of janus kinase inhibitors and its clinical implications for the management of rheumatoid arthritis

INTRODUCTION

In the realm of autoimmune rheumatic diseases, understanding JAK inhibitors (JAKi) nuances is vital. Baricitinib, tofacitinib, upaacitinib, filgotinib, and peficitinib exhibit subtle yet impactful pharmacokinetic (PK) and pharmacodynamic (PD) variations.

AREAS COVERED

This narrative review critically assesses PK and PD distinctions among globally approved JAKi for rheumatoid arthritis, which primarily guide clinical decisions in autoimmune diseases, particularly rheumatoid arthritis. It explores the intricate JAK-STAT signaling pathway, offering insights into JAKs' roles in inflammation, hematopoiesis, and immune homeostasis. Emphasis on PK parameters, including absorption, distribution, metabolism, and excretion, along with CYP3A4 drug interactions, is highlighted. The review underscores integrating PK and PD properties, considering patient-specific factors like hepatic and renal clearance, for judicious JAKi selection in RA and related autoimmune conditions. The literature has been collected from all available databases based on the review question.

EXPERT OPINION

Integrating PK and PD properties with patient-specific factors is pivotal for judicious JAKi selection. Recognizing disparities in PK and PD across diseases, ethnicities, and environmental factors is crucial for personalized JAKi choices. This expert opinion underscores the significance of a second compartment analysis, elucidating the interplay between PK and PD and its impact on JAKi efficacy.

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.

The Real-World Effectiveness, Persistence, Adherence, and Safety of Janus Kinase Inhibitor Baricitinib in Rheumatoid Arthritis: A Long-Term Study

Background/Aim: Baricitinib (BAR) is the first oral selective Janus kinase inhibitor approved in Europe for rheumatoid arthritis (RA). Real-world data are still needed to clarify its long-term benefits/risk profile. This study aimed to evaluate the effectiveness, persistence, adherence, and safety of BAR in a real-world setting. Methods: An ambispective study was conducted between October 2017 and December 2021 in RA patients starting BAR. The effectiveness was evaluated, assessing changes from the baseline of the Disease Activity Score using 28-joint counts-C reactive protein (DAS28CRP), and the achievement of low disease activity/remission. Drug persistence was evaluated using Kaplan-Meier analysis. Adherence was estimated using the medication possession ratio (MPR) and the 5-item Compliance Questionnaire for Rheumatology. Safety was assessed determining global incidence proportion and adverse event adjusted incidence rates. Results: In total, 61/64 recruited patients were finally analyzed, 83.6% were female, 78.7% were seropositive, the mean age was 58.1 (15.4) years, and the disease duration was 13.9 (8.3) years. A total of 32.8% of patients were naïve to biologics and 16.4% received BAR as monotherapy. The median exposure to BAR was 12.4 (6.6-31.2) months (range 3.1-51.4). A significant change in DAS28CRP was observed after treatment (difference -1.2, p = 0.000). 70.5% and 60.7% of patients achieved low disease activity or remission, respectively, and 50.8% (31/61) remained on BAR throughout the follow-up, with a median persistence of 31.2 (9.3-53.1) months. The average MPR was 0.96 (0.08) and all patients exhibited "good adherence" according to the questionnaire. In total, 21.3% of patients discontinued baricitinib due to toxicity. Conclusions: In our real-world practice, BAR demonstrated effectiveness, large persistence, high adherence to treatment, and an acceptable safety profile.

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.

JAK-STAT signaling in inflammation and stress-related diseases: implications for therapeutic interventions

The Janus kinase-signal transducer and transcription activator pathway (JAK-STAT) serves as a cornerstone in cellular signaling, regulating physiological and pathological processes such as inflammation and stress. Dysregulation in this pathway can lead to severe immunodeficiencies and malignancies, and its role extends to neurotransduction and pro-inflammatory signaling mechanisms. Although JAK inhibitors (Jakinibs) have successfully treated immunological and inflammatory disorders, their application has generally been limited to diseases with similar pathogenic features. Despite the modest expression of JAK-STAT in the CNS, it is crucial for functions in the cortex, hippocampus, and cerebellum, making it relevant in conditions like Parkinson's disease and other neuroinflammatory disorders. Furthermore, the influence of the pathway on serotonin receptors and phospholipase C has implications for stress and mood disorders. This review expands the understanding of JAK-STAT, moving beyond traditional immunological contexts to explore its role in stress-related disorders and CNS function. Recent findings, such as the effectiveness of Jakinibs in chronic conditions such as rheumatoid arthritis, expand their therapeutic applicability. Advances in isoform-specific inhibitors, including filgotinib and upadacitinib, promise greater specificity with fewer off-target effects. Combination therapies, involving Jakinibs and monoclonal antibodies, aiming to enhance therapeutic specificity and efficacy also give great hope. Overall, this review bridges the gap between basic science and clinical application, elucidating the complex influence of the JAK-STAT pathway on human health and guiding future interventions.

JAK inhibitors and black box warnings: what is the future for JAK inhibitors?

INTRODUCTION

Janus kinase inhibitors (JAKi) have dramatically improved the treatment of various autoimmune and myeloproliferative disorders. Recently, concern has arisen regarding their safety in patients with rheumatoid arthritis.

AREAS COVERED

Here, we provide a comprehensive summary of the major current and emerging JAKi and their indications, address recent studies on comparative safety, and provide insight into their future and use. We emphasize that the application of the research findings on a case-by-case basis should consider a patient's age, comorbidities, disease for which JAKi is being considered, disease activity, the JAKi target(s), alternate treatment options available for the patient, and the planned duration of JAKi.

EXPERT OPINION

Rheumatologists are used to prescribing therapies in which a risk-to-benefit assessment is required as well as to screening and monitoring the safety of medications. Thus, rheumatologists are already practiced in applying specific criteria to effectively screen and monitor patients who are candidates for JAKi therapy. Ongoing research will help to clarify any mechanisms underlying differential safety signals between JAK and other therapies, what the balance between risk and efficacy is, who the susceptible subpopulations are, and whether safety signals are shared between different JAKis and across indications.