Clinical efficacy of new JAK inhibitors under development. Just more of the same?

Treatment strategies for Spondyloarthritis: Implementation of precision medicine - Or "one size fits all" concept?

Spondyloarthritis (SpA) is a term to describe a group of chronic inflammatory rheumatic diseases, which have common pathophysiological, genetic, and clinical features. Under the umbrella term SpA, two main groups are subsumed: axial SpA (radiographic axSpA and non-radiographic axSpA) and peripheral SpA (with the leading representative being psoriatic arthritis (PsA) but also arthritis associated with inflammatory bowel disease (IBD), reactive arthritis, and undifferentiated pSpA). The key clinical symptom in axSpA is chronic back pain, typically with inflammatory characteristics, which starts in early adulthood, while the leading clinical manifestations of peripheral SpA (pSpA) are arthritis, enthesitis, and/or dactylitis. Furthermore, extra-musculoskeletal manifestations (EMMs) (acute anterior uveitis, psoriasis, and IBD) can accompany axial or peripheral symptoms. All these factors need to be taken into account when making treatment decisions in SpA patients. Despite the major advances in the treatment landscape over the past two decades with the introduction of biological disease-modifying anti-rheumatic drugs (bDMARDs) and most recently targeted synthetic DMARDs (tsDMARDs), a relevant proportion of patients still does not achieve the desired state of remission (=absence of disease activity). With this implementation of new treatment modalities, clinicians now have more choices to make in the treatment algorithms. However, despite generalized treatment recommendations, all factors need to be carefully considered when deciding on the optimal treatment strategy for an individual patient in clinical practice, aiming at an important first step towards personalized treatment strategies in SpA. In this narrative review, we focus on the efficacy of approved and emerging treatment options in axSpA and PsA as the main representative of pSpA and discuss their selective effect on the different manifestations associated with SpA to provide guidance on drivers of treatment decisions in specific situations.

The efficacy and safety of different Janus kinase inhibitors as monotherapy in rheumatoid arthritis: A Bayesian network meta-analysis

OBJECTIVE

This study aims to evaluate the efficacy and safety of JAK inhibitors in the treatment of patients with RA.

METHODS

The databases CNKI, VIP, Wanfang, CBM, and PubMed, Embase, Cochrane Library and Web of Science were searched to identify relevant randomized controlled trials (RCTs), all from the time of database creation to April 2024. Screening, data extraction, and risk of bias assessment (using Review Manager-5.3 software) were independently performed by at least two authors. The network meta-analysis was conducted using R 4.1.3 software. PROSPERO registration number: CRD42022370444.

RESULTS

Thirty-three RCTs included 15,961 patients The experimental groups involved six JAK inhibitors (filgotinib, tofacitinib, decernotinib, baricitinib, upadacitinib and peficitinib) and 12 interventions (different doses of the six JAK inhibitors), and the control group involved adalimumab (ADA) and placebo. Compared with placebo, all JAK inhibitors showed a significant increase in efficacy measures (ACR20/50/70). Compared with ADA, only tofacitinib, low-dose decernotinib, and high-dose peficitinib showed a significant increase in ACR20/50/70. Decernotinib ranked first in the SUCRA ranking of ACR20/50/70. In terms of safety indicators, only those differences between low-dose filgotinib and high-dose upadacitinib, low-dose tofacitinib and high-dose upadacitinib were statistically significant. Low-dose filgotinib ranked first in the SUCRA ranking with adverse events as safety indicators. Only the efficacy and safety of tofacitinib ranked higher among different SUCRA rankings.

CONCLUSION

Six JAK inhibitors have better efficacy than placebo. The superior efficacy of decernotinib and safety of low-dose filgotinib can be found in the SUCRA. However, there are no significant differences in safety between the different JAK inhibitors. Head-to-head trials, directly comparing one against each other, are required to provide more certain evidence.

Post hoc analysis of patients with rheumatoid arthritis under clinical remission in two Japanese Phase 3 trials of peficitinib treatment (RAJ3 and RAJ4)

OBJECTIVE

We evaluated remission rates and their relationship with baseline characteristics in patients with rheumatoid arthritis treated with the oral Janus kinase inhibitor peficitinib.

METHODS

This post hoc analysis of data from two Phase 3 studies (RAJ3 and RAJ4) of peficitinib (100 and 150 mg/day) in Asian rheumatoid arthritis patients investigated clinical disease activity index (CDAI) remission and low disease activity rates from baseline to Week 52. CDAI, Health Assessment Questionnaire-Disability Index, and van der Heijde-modified total Sharp score remission/low disease activity rates at Week 52 were evaluated among patients achieving CDAI remission at Weeks 12/28. Logistic regression analyses explored the relationship between baseline characteristics and CDAI remission/low disease activity rates.

RESULTS

CDAI remission rates increased over time in a dose-dependent manner in both peficitinib-treated groups. Most patients achieving CDAI remission at Weeks 12/28 also achieved remission at Week 52. Following the multivariate analysis of demographic and baseline characteristics, factors associated with the achievement of CDAI remission at Week 28 included male sex, low baseline prednisone dose (RAJ3 only), and low baseline Disease Activity Score 28-C-reactive protein (RAJ4 only).

CONCLUSIONS

Peficitinib demonstrated persistent efficacy in clinical remission to Week 52. Baseline characteristics associated with CDAI remission were mostly consistent with previous studies using other disease-modifying antirheumatic drugs.

VX-509 attenuates the stemness characteristics of colorectal cancer stem-like cells by regulating the epithelial-mesenchymal transition through Nodal/Smad2/3 signaling

BACKGROUND

Colorectal cancer stem cells (CCSCs) are heterogeneous cells that can self-renew and undergo multidirectional differentiation in colorectal cancer (CRC) patients. CCSCs are generally accepted to be important sources of CRC and are responsible for the progression, metastasis, and therapeutic resistance of CRC. Therefore, targeting this specific subpopulation has been recognized as a promising strategy for overcoming CRC.

AIM

To investigate the effect of VX-509 on CCSCs and elucidate the underlying mechanism.

METHODS

CCSCs were enriched from CRC cell lines by in conditioned serum-free medium. Western blot, Aldefluor, transwell and tumorigenesis assays were performed to verify the phenotypic characteristics of the CCSCs. The anticancer efficacy of VX-509 was assessed in HCT116 CCSCs and HT29 CCSCs by performing cell viability analysis, colony formation, sphere formation, flow cytometry, and western blotting assessments in vitro and tumor growth, immunohistochemistry and immunofluorescence assessments in vivo.

RESULTS

Compared with parental cells, sphere cells derived from HCT116 and HT29 cells presented increased expression of stem cell transcription factors and stem cell markers and were more potent at promoting migration and tumorigenesis, demonstrating that the CRC sphere cells displayed CSC features. VX-509 inhibited the tumor malignant biological behavior of CRC-stem-like cells, as indicated by their proliferation, migration and clonality in vitro, and suppressed the tumor of CCSC-derived xenograft tumors in vivo. Besides, VX-509 suppressed the CSC characteristics of CRC-stem-like cells and inhibited the progression of epithelial-mesenchymal transition (EMT) signaling in vitro. Nodal was identified as the regulatory factor of VX-509 on CRC stem-like cells through analyses of differentially expressed genes and CSC-related database information. VX-509 markedly downregulated the expression of Nodal and its downstream phosphorylated Smad2/3 to inhibit EMT progression. Moreover, VX-509 reversed the dedifferentiation of CCSCs and inhibited the progression of EMT induced by Nodal overexpression.

CONCLUSION

VX-509 prevents the EMT process in CCSCs by inhibiting the transcription and protein expression of Nodal, and inhibits the dedifferentiated self-renewal of CCSCs.

Current Approach to Risk Factors and Biomarkers of Intestinal Fibrosis in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), especially Crohn's disease (CD), characterized by a chronic inflammatory process and progressive intestinal tissue damage, leads to the unrestrained proliferation of mesenchymal cells and the development of bowel strictures. Complications induced by fibrosis are related to high rates of morbidity and mortality and lead to a substantial number of hospitalizations and surgical procedures, generating high healthcare costs. The development of easily obtained, reliable fibrogenesis biomarkers is essential to provide an important complementary tool to existing diagnostic and prognostic methods in IBD management, guiding decisions on the intensification of pharmacotherapy, proceeding to surgical methods of treatment and monitoring the efficacy of anti-fibrotic therapy in the future. The most promising potential markers of fibrosis include cartilage oligomeric matrix protein (COMP), hepatocyte growth factor activator (HGFA), and fibronectin isoform- extra domain A (ED-A), as well as antibodies against granulocyte macrophage colony-stimulating factor (GM-CSF Ab), cathelicidin (LL-37), or circulatory miRNAs: miR-19a-3p and miR-19b-3p. This review summarizes the role of genetic predisposition, and risk factors and serological markers potentially contributing to the pathophysiology of fibrotic strictures in the course of IBD.

Targeting the Tyrosine Kinase 2 (TYK2) Pseudokinase Domain: Discovery of the Selective TYK2 Inhibitor ABBV-712

Tyrosine kinase 2 (TYK2) is a nonreceptor tyrosine kinase that belongs to the JAK family also comprising JAK1, JAK2, and JAK3. TYK2 is an attractive target for various autoimmune diseases as it regulates signal transduction downstream of IL-23 and IL-12 receptors. Selective TYK2 inhibition offers a differentiated clinical profile compared to currently approved JAK inhibitors. However, selectivity for TYK2 versus other JAK family members has been difficult to achieve with small molecules that inhibit the catalytically active kinase domain. Successful targeting of the TYK2 pseudokinase domain as a strategy to achieve isoform selectivity was recently exemplified with deucravacitinib. Described herein is the optimization of selective TYK2 inhibitors targeting the pseudokinase domain, resulting in the discovery of the clinical candidate ABBV-712 (21).

Management of Rheumatoid Arthritis: Possibilities and Challenges of Mesenchymal Stromal/Stem Cell-Based Therapies

Rheumatoid arthritis (RA) is a highly prevalent, chronic, and progressive autoimmune disorder primarily affecting joints and muscles. The associated inflammation, pain, and motor restriction negatively impact patient quality of life (QOL) and can even contribute to premature mortality. Further, conventional treatments such as antiinflammatory drugs are only symptomatic. Substantial progress has been made on elucidating the etiopathology of overt RA, in particular the contributions of innate and adaptive immune system dysfunction to chronic inflammation. Although the precise mechanisms underlying onset and progression remain elusive, the discovery of new drug targets, early diagnosis, and new targeted treatments have greatly improved the prognosis and QOL of patients with RA. However, a sizable proportion of patients develop severe adverse effects, exhibit poor responses, or cannot tolerate long-term use of these drugs, necessitating more effective and safer therapeutic alternatives. Mounting preclinical and clinical evidence suggests that the transplantation of multipotent adult stem cells such as mesenchymal stromal/stem cells is a safe and effective treatment strategy for controlling chronic inflammation and promoting tissue regeneration in patients with intractable diseases, including RA. This review describes the current status of MSC-based therapies for RA as well as the opportunities and challenges to broader clinical application.

Dose-escalating ruxolitinib for refractory hemophagocytic lymphohistiocytosis

Background

Hemophagocytic lymphohistiocytosis (HLH) is a severe disorder characterized by excessive secretion of cytokines. Even with the recommended HLH-94/2004 regimen, over 30% of patients remain refractory to frontline therapy or relapse after an initial response, leading to poor clinical outcomes. Ruxolitinib, a JAK1/2 inhibitor targets key cytokines in HLH, has shown promising therapeutic effects. However, there has been little attention given to patients who do not respond to ruxolitinib and whether an escalating dose can provide a resolution.

Methods

This study analyzed eight HLH patients who received dose-escalating ruxolitinib who had previously failed to respond to the general dose. The efficacy and safety were mainly analyzed.

Results

Overall, four out of eight (50%) patients achieved better remission after dose escalation. Two patients who only showed improvement with the general dose achieved complete remission (CR) after dose escalation, and the other two patients also achieved CR after dose escalation when they did not respond to the general dose. The median time to achieve the best overall response was 18.5 days (IQR 13.25-23.75 days). There was no correlation of treatment outcome with blood count, liver function, LDH, cytokines, ferritin levels, NK cell activity, or the time to initiation of ruxolitinib and maximum dosage. The etiology of HLH (p=0.029) and level of sCD25 (p=0.021) correlated with treatment response to dose-escalating ruxolitinib. The area of sCD25 under the ROC curve was 0.8125 (95% CI 0.5921 to 1.033, p=0.035) when using 10,000 pg/ml as the cut-off value for predicting therapeutic effects. After a median follow-up of 159 days, two patients died, and the estimated 2-month overall survival rate was 75%. Adverse effects possibly related to the dose-escalating of ruxolitinib included two cases of extremity pain and one of aminotransferase increased. No grade 3 or higher adverse events were reported.

Conclusion

This is the first comprehensive study on the use of dose-escalating ruxolitinib in HLH. Ruxolitinib at an escalated dose represent a viable and relatively safe solution for managing refractory HLH. The levels of sCD25 (with a cut-off of 10000pg/ml) can serve as an indicator for early consideration of chemotherapy during treatment.

Temperature-triggered in situ forming lipid mesophase gel for local treatment of ulcerative colitis

Ulcerative colitis is a chronic inflammatory bowel disease that strongly affects patient quality of life. Side effects of current therapies necessitate new treatment strategies that maximise the drug concentration at the site of inflammation, while minimizing systemic exposure. Capitalizing on the biocompatible and biodegradable structure of lipid mesophases, we present a temperature-triggered in situ forming lipid gel for topical treatment of colitis. We show that the gel is versatile and can host and release drugs of different polarities, including tofacitinib and tacrolimus, in a sustained manner. Further, we demonstrate its adherence to the colonic wall for at least 6 h, thus preventing leakage and improving drug bioavailability. Importantly, we find that loading known colitis treatment drugs into the temperature-triggered gel improves animal health in two mouse models of acute colitis. Overall, our temperature-triggered gel may prove beneficial in ameliorating colitis and decreasing adverse effects associated with systemic application of immunosuppressive treatments.

JAK inhibition in the treatment of inflammatory rheumatic diseases

The most common immune-mediated inflammatory rheumatic diseases, rheumatoid arthritis, psoriatic arthritis and axial spondyloarthritis and have reached significant advances in recent years with the introduction of biological therapies against cytokines and immune cells, but also against intracellular enzymes, specifically Janus kinases (JAKs). Intracellular JAK signalling is activated by binding of various cytokines or growth factors to the respective cellular receptors, allowing the activation of STAT (Signal Transducers and Activators of Transcription) transcription factors and ultimately the transcription of genes with important roles during the innate and adaptive immune response. Four Janus kinases have been described: JAK1, JAK2, JAK3 and tyrosine kinase-2 (TYK2). Four JAK inhibitors (tofacitinib, baricitinib, upadacitinib and filgotinib) are currently approved for the treatment of rheumatoid arthritis, and some for the treatment of psoriatic arthritis and axial spondyloarthritis. JAK inhibitors have varying selectivity against individual kinases. Some JAK inhibitors are being tested in other rarer systemic connective tissue diseases. The general advantages of JAK inhibitors are oral administration, rapid onset of action, and efficacy in monotherapy. The safety profile of JAK inhibitors compared with biologic therapy appears to be comparable, with a higher incidence of herpes zoster, and an increased incidence of major cardiovascular disease, thromboembolic complications, and cancer in at-risk patients is discussed. The aim of this paper will be to summarize the latest findings on JAK inhibitors in approved indications for the most common rheumatic diseases.

Sarcoidosis: Updates on therapeutic drug trials and novel treatment approaches

Sarcoidosis is a systemic granulomatous inflammatory disease of unknown etiology. It affects the lungs in over 90% of patients yet extra-pulmonary and multi-organ involvement is common. Spontaneous remission of disease occurs commonly, nonetheless, over 50% of patients will require treatment and up to 30% of patients will develop a chronic progressive non-remitting disease with marked pulmonary fibrosis leading to significant morbidity and death. Guidelines outlining an immunosuppressive treatment approach to sarcoidosis were recently published, however, the strength of evidence behind many of the guideline recommended drugs is weak. None of the drugs currently used for the treatment of sarcoidosis have been rigorously studied and prescription of these drugs is often based on off-label” indications informed by experience with other diseases. Indeed, only two medications [prednisone and repository corticotropin (RCI) injection] currently used in the treatment of sarcoidosis are approved by the United States Food and Drug Administration. This situation results in significant reimbursement challenges especially for the more advanced (and often more effective) drugs that are favored for severe and refractory forms of disease causing an over-reliance on corticosteroids known to be associated with significant dose and duration dependent toxicities. This past decade has seen a renewed interest in developing new drugs and exploring novel therapeutic pathways for the treatment of sarcoidosis. Several of these trials are active randomized controlled trials (RCTs) designed to recruit relatively large numbers of patients with a goal to determine the safety, efficacy, and tolerability of these new molecules and therapeutic approaches. While it is an exciting time, it is also necessary to exercise caution. Resources including research dollars and most importantly, patient populations available for trials are limited and thus necessitate that several of the challenges facing drug trials and drug development in sarcoidosis are addressed. This will ensure that currently available resources are judiciously utilized. Our paper reviews the ongoing and anticipated drug trials in sarcoidosis and addresses the challenges facing these and future trials. We also review several recently completed trials and draw lessons that should be applied in future.

The Risk of Infections Associated With JAK Inhibitors in Rheumatoid Arthritis: A Systematic Review and Network Meta-analysis

BACKGROUND/OBJECTIVE

The Janus kinases (JAKs) are cytoplasmic tyrosine kinases associated with membrane cytokine receptors that mediate signaling of multiple cytokines and growth factors, contributing to the pathogenesis of multiple autoimmune disorders. The JAK inhibitors are a new class of targeted therapies with proven efficacy in treating rheumatoid arthritis but are associated with an increased risk of infections. This study is aimed at comparing the relative safety of the different JAK inhibitors with regard to the risk of serious infections in patients with rheumatoid arthritis.

METHODS

PubMed, EMBASE, Cochrane Library, and clinicaltrials.gov were searched to identify randomized controlled trials evaluating the efficacy and safety of JAK inhibitors in patients with rheumatoid arthritis. The outcomes assessed were the risk of total and serious infections, tuberculosis, and herpes zoster. Sensitivity analysis disaggregated the results according to background therapy and licensed doses of JAK inhibitors.

RESULTS

Thirty-seven randomized controlled trials that were included met the inclusion criteria. Compared with filgotinib, adalimumab (4.81; 95% confidence interval [CI], 1.39-16.66), etanercept (6.04; 95% CI, 1.79-20.37), peficitinib (7.56; 95% CI, 1.63-35.12), tofacitinib (4.29; 95% CI, 1.43-12.88), and upadacitinib (4.35; 95% CI, 1.46-13.00) have an increased risk of herpes zoster infection. Risk differences between the drugs became statistically nonsignificant when the sensitivity analysis was conducted.

CONCLUSIONS

The risk of infections seems to be similar among the currently approved JAK inhibitor drugs. Although the initial results suggested that filgotinib could have a reduced risk of herpes zoster, the sensitivity analyses did not support those findings.

Investigation of Janus Kinase (JAK) Inhibitors for Lung Delivery and the Importance of Aldehyde Oxidase Metabolism

The Janus family of tyrosine kinases (JAK1, JAK2, JAK3, and TYK2) play an essential role in the receptor signaling of cytokines that have been implicated in the pathogenesis of severe asthma, and there is emerging interest in the development of small-molecule-inhaled JAK inhibitors as treatments. Here, we describe the optimization of a quinazoline series of JAK inhibitors and the results of mouse lung pharmacokinetic (PK) studies where only low concentrations of parent compound were observed. Subsequent investigations revealed that the low exposure was due to metabolism by aldehyde oxidase (AO), so we sought to identify quinazolines that were not metabolized by AO. We found that specific substituents at the quinazoline 2-position prevented AO metabolism and this was rationalized through computational docking studies in the AO binding site, but they compromised kinome selectivity. Results presented here highlight that AO metabolism is a potential issue in the lung.

Efficacy and safety of filgotinib alone and in combination with methotrexate in Japanese patients with active rheumatoid arthritis and limited or no prior exposure to methotrexate: Subpopulation analyses of 24-week data of a global phase 3 study (FINCH 3)

OBJECTIVES

To evaluate the efficacy and safety of filgotinib for Japanese patients with rheumatoid arthritis (RA) and limited or no prior methotrexate (MTX) exposure.

METHODS

Data up to 24 weeks were analysed for 71 Japanese patients from a 52-week global Phase 3 study. Patients with RA and limited or no prior MTX exposure were randomised in a 2:1:1:2 ratio to filgotinib 200 mg plus MTX, filgotinib 100 mg plus MTX, filgotinib 200 mg, or MTX. Maximum MTX dose was 15 mg/week. Primary endpoint was proportion achieving 20% improvement in American College of Rheumatology criteria (ACR20) at Week 24.

RESULTS

Week 24 ACR20 rates in Japanese patients were 82.6%, 90.9%, 83.3%, and 80.0% for filgotinib 200 mg plus MTX, filgotinib 100 mg plus MTX, filgotinib 200 mg, and MTX, respectively. Greater ACR20 rates with filgotinib vs MTX occurred at Week 2. Greater proportions receiving filgotinib vs MTX achieved DAS28-CRP <2.6 at Weeks 12 and 24. Adverse event rates were comparable across treatments and between the Japanese and overall populations.

CONCLUSIONS

While Week 24 ACR20 rates were similar, filgotinib provided faster responses and higher remission rates vs MTX. In Japanese patients with RA and limited or no prior MTX exposure, filgotinib was generally well tolerated.

Risk of venous thromboembolism associated with Janus kinase inhibitors for rheumatoid arthritis: case presentation and literature review

Janus kinase (JAK) inhibitors have been developed as disease-modifying antirheumatic drugs. Despite the positive therapeutic impacts of JAK inhibitors, concerns have been raised regarding the risk of venous thromboembolism (VTE), such as deep vein thrombosis (DVT) and pulmonary embolism (PE). A recent post hoc safety analysis of placebo-controlled trials of JAK inhibitors in rheumatoid arthritis (RA) reported an imbalance in the incidence of VTE for a 4-mg daily dose of baricitinib versus placebo. In a recent postmarketing surveillance trial for RA, a significantly higher incidence of PE was reported in treatment with tofacitinib (10 mg twice daily) compared with tofacitinib 5 mg or tumor necrosis factor inhibitors. We also experienced a case of massive PE occurring 3 months after starting baricitinib (4 mg once daily) for multiple biologic-resistant RA. Nevertheless, the evidence to support the role of JAK inhibitors in VTE risk remains insufficient. There are a number of predisposing conditions and risk factors for VTE. In addition to the known risk factors that can provoke VTE, advanced age, obesity, diabetes mellitus, hypertension, hyperlipidemia, and smoking can also contribute to its development. Greater VTE risk is noted in patients with chronic inflammatory conditions, particularly RA patients with uncontrolled disease activity and any comorbidity. Prior to the initiation of JAK inhibitors, clinicians should consider both the number and strength of VTE risk factors for each patient. In addition, clinicians should advise patients to seek prompt medical help if they develop clinical signs and symptoms that suggest VTE/PE.

Key Points • Patients with rheumatoid arthritis (RA) are at increased risk of venous thromboembolism (VTE), especially those with uncontrolled, high disease activity and those with comorbidities. • In addition to the well-known risk factors that provoke VTE events, advanced age and cardiovascular risk factors, such as obesity, diabetes mellitus, hypertension, hyperlipidemia, and smoking, should be considered risk factors for VTE. • Although a signal of VTE/pulmonary embolism (PE) risk with JAK inhibitors has been noted in RA patients who are already at high risk, the evidence is currently insufficient to support the increased risk of VTE during RA treatment with JAK inhibitors. • If there are no suitable alternatives, clinicians should prescribe JAK inhibitors with caution, considering both the strength of individual risk factors and the cumulative weight of all risk factors for each patient.

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.

Real-world single centre use of JAK inhibitors across the rheumatoid arthritis pathway

OBJECTIVES

To evaluate real-world efficacy of approved JAK inhibitors (JAKi) tofacitinib and baricitinib in a large, single-centre cohort of RA patients across the treatment pathway, including those refractory to multiple biologic drugs.

METHODS

All RA patients, treated with tofacitinib (from time of compassionate access scheme) or baricitinib since approval in 2017 had DAS28-CRP scores and components recorded at baseline, 3 and 6 months (with retrospective data for compassionate access scheme). Efficacy was evaluated in the total cohort, each treatment group, and subgroups of number of prior biologic classes failed.

RESULTS

One hundred and fifteen patients were treated with a JAKi (tofacitinib 54, baricitinib 69, 8 both); 76.4% female; mean (s.d.) age 57.3 (14.3) years. On average patients had received three previous bDMARDs; 11 (9.6%) were bDMARD naïve. Combined group baseline DAS28-CRP (s.d.) 5.62(1.14) improved by 1.49(1.44) and 1.67(1.61) at 3 and 6 months, respectively, comparable in individual JAKi groups; with 24% in at least low disease activity at 3 months. The biggest improvement was observed in the biologic-naïve group (mean DAS28-CRP improved from 5.16-2.14 after 6 months); while those with prior exposure to minimum three bDMARD classes had DAS28-CRP improvement of >1.2. Five out of 8 patients treated with both JAKi sequentially responded. Twelve patients previously unresponsive to IL-6 blockade responded to JAKi. No unexpected safety events were recorded. Two cases of venous thromboembolism were observed.

CONCLUSION

JAK inhibition is effective in a real-world population of RA patients, including in a subset of patients refractory to multiple previous bDMARDs.

Current and future status of JAK inhibitors

An enhanced understanding of the importance of Janus kinase (JAK) and signal transducer and activator of transcription (STAT) signalling in multiple disease states has led to an increasing applicability of therapeutic intervention with JAK inhibitors. These agents have revolutionised treatments for a heterogeneous group of disorders, such as myeloproliferative neoplasms, rheumatoid arthritis, inflammatory bowel disease, and multiple immune-driven dermatological diseases, exemplifying rapid bench-to-bedside translation. In this Therapeutics paper, we summarise the currently available data concerning the successes and safety of an array of JAK inhibitors and hypothesise on how these fields could develop.

Efficacy and safety of filgotinib in combination with methotrexate in Japanese patients with active rheumatoid arthritis who have an inadequate response to methotrexate: Subpopulation analyses of 24-week data of a global phase 3 study (FINCH 1)

OBJECTIVES

Evaluate the efficacy and safety of the Janus kinase-1 inhibitor filgotinib in Japanese patients with rheumatoid arthritis (RA) and inadequate response to methotrexate (MTX).

METHODS

Data from 147 Japanese patients in FINCH 1, a 52-week global Phase 3 study, were analysed up to 24 weeks. Patients received once-daily filgotinib 200 or 100 mg, biweekly adalimumab, or placebo, all with stable background MTX.

RESULTS

In the Japanese population, American College of Rheumatology 20% response rates at Week 12 (primary endpoint) were 77.5%, 65.9%, 53.6%, and 36.8% for filgotinib 200 mg, filgotinib 100 mg, adalimumab, and placebo. Proportions of patients achieving Disease Activity Score with 28 joints <2.6 at Week 24: filgotinib 200 mg, 65.0%; filgotinib 100 mg, 51.2%; adalimumab, 42.9%; and placebo, 5.3%. Incidence rates of serious infections: filgotinib 200 mg, 2.5%; filgotinib 100 mg, 0%; adalimumab, 10.7%; and placebo, 5.3%. Treatment-emergent laboratory abnormalities Grade ≥3 occurred in five (12.5%) filgotinib 200 mg, three (7.3%) filgotinib 100 mg, one (3.6%) adalimumab, and no placebo patients. No deaths were reported among Japanese patients.

CONCLUSIONS

Filgotinib once daily combined with MTX was effective and generally safe and well tolerated up to Week 24 in Japanese patients with RA and inadequate response to MTX.

Type I Interferons in the Pathogenesis and Treatment of Autoimmune Diseases

Type I interferons (IFN-Is) are a very important group of cytokines that are produced by innate immune cells but also act on adaptive immune cells. IFN-Is possess antiviral, antitumor, and anti-proliferative effects, as well are associated with the initiation and maintenance of autoimmune disorders. Studies have shown that aberrantly expressed IFN-Is and/or type I IFN-inducible gene signatures in the serum or tissues of patients with autoimmune disorders are linked to their pathogenesis, clinical manifestations, and disease activity. Type I interferonopathies with mutations in genes impacting the type I IFN signaling pathway have shown symptoms and characteristics similar to those of systemic lupus erythematosus (SLE). Furthermore, both interventions in animal models and clinical trials of therapies targeting the type I IFN signaling pathway have shown efficacy in the treatment of autoimmune diseases. Our review aims to summarize the functions and targeted therapies (as well as clinical trials) of IFN-Is in both adult and pediatric autoimmune diseases, such as SLE, pediatric SLE (pSLE), rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), juvenile dermatomyositis (JDM), Sjögren syndrome (SjS), and systemic sclerosis (SSc), discussing the potential abnormal regulation of transcription factors and epigenetic modifications and providing a potential mechanism for pathogenesis and therapeutic strategies for future clinical use.

The Therapeutic Landscape of Rheumatoid Arthritis: Current State and Future Directions

Rheumatoid arthritis (RA) is a debilitating autoimmune disease with grave physical, emotional and socioeconomic consequences. Despite advances in targeted biologic and pharmacologic interventions that have recently come to market, many patients with RA continue to have inadequate response to therapies, or intolerable side effects, with resultant progression of their disease. In this review, we detail multiple biomolecular pathways involved in RA disease pathogenesis to elucidate and highlight pathways that have been therapeutic targets in managing this systemic autoimmune disease. Here we present an up-to-date accounting of both emerging and approved pharmacological treatments for RA, detailing their discovery, mechanisms of action, efficacy, and limitations. Finally, we turn to the emerging fields of bioengineering and cell therapy to illuminate possible future targeted therapeutic options that combine material and biological sciences for localized therapeutic action with the potential to greatly reduce side effects seen in systemically applied treatment modalities.

Off-Patent Biological and Biosimilar Medicines in Belgium: A Market Landscape Analysis

Background and objective: Best-value biological medicines may generate competition in the off-patent biologicals market, resulting in having more resources available to provide patients with access to necessary medicines while maintaining high-quality care. Belgium is a country known to have low biosimilar market shares, suggesting a malfunctioning market for off-patent biologicals. This study aims to gain an in-depth understanding of the Belgian off-patent biologicals market, by looking at the evolution in volumes and costs of the relevant products in the market. Methods: This study included a combination of quantitative and qualitative research methods. The quantitative part of this study consisted of the analysis of market data obtained by the National Institute for Health and Disability Insurance (NIHDI) for all relevant products in the Belgian off-patent biologicals market (i.e. TNF-inhibitors, insulins, granulocyte colony-stimulating factors, epoetins, rituximab, trastuzumab). In addition, for the qualitative part of this study, semi-structured interviews with Belgian stakeholders were conducted between December 2019 and March 2020. Results: Belgian market data and stakeholder perceptions suggest a suboptimal market environment for off-patent biological and biosimilar medicines. Shifts are observed after loss of exclusivities of originator biologicals toward second-generation products or new therapeutic class products, at a higher cost and often limited added value. Moreover, cost reductions for off-patent biologicals after biosimilar market entry are mainly determined by mandatory price reductions applicable to both originator and biosimilar products, and not by lower prices induced by competition. For products used in the retail setting, significant mandatory price reductions for both originator and reference products with low biosimilar volumes were pointed out as the main reasons for the lack of price competition. For products dispensed in hospitals, the hospital financing system is important. First, it does not always encourage the use of lower cost alternatives. Second, competition mainly takes place at the level of confidential discounts in tenders. Most interviewees acknowledged the lack of a competitive environment, which is not supportive of a sustainable Belgian off-patent biologicals market. Conclusion: Market data and stakeholder perceptions indicate that the sustainability of the Belgian market for off-patent biologicals is challenged. A sustainable market ensures access to biological therapies now and in the future.

Safety and Pharmacokinetics of the Oral TYK2 Inhibitor PF-06826647: A Phase I, Randomized, Double-Blind, Placebo-Controlled, Dose-Escalation Study

Selective inhibition of tyrosine kinase 2 (TYK2) may offer therapeutic promise in inflammatory conditions, with its role in downstream pro-inflammatory cytokine signaling. In this first-in-human study, we evaluated the safety, tolerability, and pharmacokinetics (PK) of a novel TYK2 inhibitor, PF-06826647, in healthy participants. This phase I, randomized, double-blind, placebo-controlled, parallel-group study included two treatment periods (single ascending dose (SAD) and multiple ascending dose (MAD)) in healthy participants and a cohort of healthy Japanese participants receiving 400 mg q.d. or placebo in the MAD period (NCT03210961). Participants were randomly assigned to PF-06826647 or placebo (3:1). Participants received a single oral study drug dose of 3, 10, 30, 100, 200, 400, or 1,600 mg (SAD period), then 30, 100, 400, or 1,200 mg q.d. or 200 mg b.i.d. for 10 days (MAD period). Safety (adverse events (AEs), vital signs, and clinical laboratory parameters), tolerability, and PK were assessed. Overall, 69 participants were randomized to treatment, including six Japanese participants. No deaths, serious AEs, severe AEs, or AEs leading to dose reduction or temporary/permanent discontinuation were observed. All AEs were mild in severity. No clinically relevant laboratory abnormalities or changes in vital signs were detected. PF-06826647 was rapidly absorbed with a median time to maximum plasma concentration of 2 hours in a fasted state, with modest accumulation (< 1.5-fold) after multiple dosing and low urinary recovery. PF-06826647 was well-tolerated, with an acceptable safety profile for doses up to 1,200 mg q.d. for 10 days, supporting further testing in patients.

JAK Inhibitors and Modulation of B Cell Immune Responses in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, systemic immune-mediated inflammatory disease that can lead to joint destruction, functional disability and substantial comorbidity due to the involvement of multiple organs and systems. B cells have several important roles in RA pathogenesis, namely through autoantibody production, antigen presentation, T cell activation, cytokine release and ectopic lymphoid neogenesis. The success of B cell depletion therapy with rituximab, a monoclonal antibody directed against CD20 expressed by B cells, has further supported B cell intervention in RA development. Despite the efficacy of synthetic and biologic disease modifying anti-rheumatic drugs (DMARDs) in the treatment of RA, few patients reach sustained remission and refractory disease is a concern that needs critical evaluation and close monitoring. Janus kinase (JAK) inhibitors or JAKi are a new class of oral medications recently approved for the treatment of RA. JAK inhibitors suppress the activity of one or more of the JAK family of tyrosine kinases, thus interfering with the JAK-Signal Transducer and Activator of Transcription (STAT) signaling pathway. To date, there are five JAK inhibitors (tofacitinib, baricitinib, upadacitinib, peficitinib and filgotinib) approved in the USA, Europe and/ or Japan for RA treatment. Evidence from the literature indicates that JAK inhibitors interfere with B cell functions. In this review, the main results obtained in clinical trials, pharmacokinetic, in vitro and in vivo studies concerning the effects of JAK inhibitors on B cell immune responses in RA are summarized.

Biologic and advanced immunomodulating therapeutic options for sarcoidosis: a clinical update

Introduction: Sarcoidosis is a multi-organ disease with a wide range of clinical manifestations and outcomes. A quarter of sarcoidosis patients require long-term treatment for chronic disease. In this group, corticosteroids and cytotoxic agents be insufficient to control diseaseAreas covered: Several biologic agents have been studied for treatment of chronic pulmonary and extra-pulmonary disease. A review of the available literature was performed searching PubMed and an expert opinion regarding specific therapy was developed.Expert opinion: These agents have the potential of treating patients who have progressive disease. Many of these agents have different mechanisms of action, response rates, and toxicity profiles.

Efficacy and safety of filgotinib in Japanese patients with refractory rheumatoid arthritis: Subgroup analyses of a global phase 3 study (FINCH 2)

OBJECTIVES

To evaluate efficacy and safety of filgotinib in Japanese RA patients who have failed or were intolerant to one or more biologic disease-modifying antirheumatic drugs (bDMARD) from the global FINCH 2 study (NCT02873936).

METHODS

This subgroup analysis was performed using the predefined statistical analyses. The FINCH 2 study is a randomized, double-blind, placebo-controlled, Phase 3 study in adult RA patients with inadequate response to bDMARDs. The randomized patients were treated with once-daily filgotinib 200 mg, filgotinib 100 mg or placebo on a background of csDMARDs for 24 weeks.

RESULTS

Of 449 patients enrolled in the overall population, 40 patients were enrolled from Japan. In the Japanese population, the American College of Rheumatology 20% response rates at week 12 (primary endpoint) were 83.3% and 53.3% for filgotinib, 200 mg and 100 mg, respectively, vs 30.8% for placebo. Filgotinib was well tolerated, similar to the overall population.

CONCLUSIONS

Both doses of once-daily filgotinib 200 mg and filgotinib 100 mg were effective, and generally well-tolerated in Japanese patients with active refractory RA.

The JAK1 Selective Inhibitor ABT 317 Blocks Signaling Through Interferon-γ and Common γ Chain Cytokine Receptors to Reverse Autoimmune Diabetes in NOD Mice

Cytokines that signal through the JAK-STAT pathway, such as interferon-γ (IFN-γ) and common γ chain cytokines, contribute to the destruction of insulin-secreting β cells by CD8⁺ T cells in type 1 diabetes (T1D). We previously showed that JAK1/JAK2 inhibitors reversed autoimmune insulitis in non-obese diabetic (NOD) mice and also blocked IFN-γ mediated MHC class I upregulation on β cells. Blocking interferons on their own does not prevent diabetes in knockout NOD mice, so we tested whether JAK inhibitor action on signaling downstream of common γ chain cytokines, including IL-2, IL-7 IL-15, and IL-21, may also affect the progression of diabetes in NOD mice. Common γ chain cytokines activate JAK1 and JAK3 to regulate T cell proliferation. We used a JAK1-selective inhibitor, ABT 317, to better understand the specific role of JAK1 signaling in autoimmune diabetes. ABT 317 reduced IL-21, IL-2, IL-15 and IL-7 signaling in T cells and IFN-γ signaling in β cells, but ABT 317 did not affect GM-CSF signaling in granulocytes. When given in vivo to NOD mice, ABT 317 reduced CD8⁺ T cell proliferation as well as the number of KLRG⁺ effector and CD44^hiCD62L^lo effector memory CD8⁺ T cells in spleen. ABT 317 also prevented MHC class I upregulation on β cells. Newly diagnosed diabetes was reversed in 94% NOD mice treated twice daily with ABT 317 while still on treatment at 40 days and 44% remained normoglycemic after a further 60 days from discontinuing the drug. Our results indicate that ABT 317 blocks common γ chain cytokines in lymphocytes and interferons in lymphocytes and β cells and are thus more effective against diabetes pathogenesis than IFN-γ receptor deficiency alone. Our studies suggest use of this class of drug for the treatment of type 1 diabetes.

Development of JAK inhibitors for the treatment of immune-mediated diseases: kinase-targeted inhibitors and pseudokinase-targeted inhibitors

JAKs are a family of intracellular tyrosine kinases consisting of four members, JAK1, JAK2, JAK3, and TYK2. They are key components of the JAK-STAT pathway that transmit signals of many cytokines involved in the pathogenesis of numerous immune-mediated diseases and have been major molecular targets in developing new drugs for the treatment of such diseases. Some small-molecule inhibitors of JAKs have been approved by the FDA for rheumatoid arthritis, psoriatic arthritis, and inflammatory bowel disease. Now, newer JAK inhibitors with isoform-selectivity among the four different JAKs are being developed, with the aim of improving clinical outcomes compared with earlier developed drugs with pan-JAK inhibition. Most of these selective inhibitors target the kinase domains of JAKs, functioning through the traditional inhibition mode of kinases; but recently those that target their pseudokinase domains, allosterically inhibiting the enzymes, have been under development. In this review, key characteristics, efficacy, and safety of FDA-approved and representative drugs in late stages of development are briefly described in order to provide clinical implications with respect to JAK inhibitor selectivity and future development perspectives. The recent development of pseudokinase-targeted inhibitors of JAKs is also included.

Tofacitinib and Baricitinib Are Taken up by Different Uptake Mechanisms Determining the Efficacy of Both Drugs in RA

Background: Rheumatoid arthritis (RA) is a systemic autoimmune disease in which synovial fibroblasts (SF) play a key role. Baricitinib and Tofacitinib both act intracellularly, blocking the ATP-binding side of JAK proteins and thereby the downstream signalling pathway via STAT-3. Therefore, we investigated the role of organic cation transporters (OCTs) in Baricitinib and Tofacitinib cellular transport. Methods: OCT expression was analysed in SF isolated from RA and osteoarthritis (OA) patients, as well as peripheral blood mononuclear cells. The interaction of Baricitinib and Tofacitinib with OCTs was investigated using quenching experiments. The intracellular accumulation of both drugs was quantified using LC/MS. Target inhibition for both drugs was tested using Western blot for phosphorylated JAK1 and STAT3 upon stimulation with IL-6. Results: MATE-1 expression increased in OASF compared to RASF. The other OCTs were not differentially expressed. The transport of Baricitinib was not OCT dependent. Tofacitinib; however, was exported from RASF in a MATE-1 dependent way. Tofacitinib and Baricitinib showed comparable inhibition of downstream signalling pathways. Conclusion: We observed different cellular uptake strategies for Baricitinib and Tofacitinib. Tofacitinib was exported out of healthy cells due to the increased expression of MATE1. This might make Tofacitinib the favourable drug.

Small Molecule Inhibitors in the Treatment of Rheumatoid Arthritis and Beyond: Latest Updates and Potential Strategy for Fighting COVID-19

The development of biological disease-modifying antirheumatic drugs (bDMARDs) and target synthetic DMARDs (tsDMARDs), also known as small molecule inhibitors, represent a breakthrough in rheumatoid arthritis (RA) treatment. The tsDMARDs are a large family of small molecules targeting mostly the several types of kinases, which are essential in downstream signaling of pro-inflammatory molecules. This review highlights current challenges associated with the treatment of RA using small molecule inhibitors targeting intracellular JAKs/MAPKs/NF-κB/SYK-BTK signaling pathways. Indeed, we have provided the latest update on development of small molecule inhibitors, their clinical efficacy and safety as a strategy for RA treatment. On the other hand, we have highlighted the risk and adverse effects of tsDMARDs administration including, among others, infections and thromboembolism. Therefore, performance of blood tests or viral infection screening should be recommended before the tsDMARDs administration. Interestingly, recent events of SARS-CoV-2 outbreak have demonstrated the potential use of small molecule inhibitors not only in RA treatment, but also in fighting COVID-19 via blocking the viral entry, preventing of hyperimmune activation and reducing cytokine storm. Thus, small molecule inhibitors, targeting wide range of pro-inflammatory singling pathways, may find wider implications not only for the management of RA but also in the controlling of COVID-19.

JAK-Inhibitors for the Treatment of Rheumatoid Arthritis: A Focus on the Present and an Outlook on the Future

Janus kinase inhibitors (JAKi) belong to a new class of oral targeted disease-modifying drugs which have recently revolutionized the therapeutic panorama of rheumatoid arthritis (RA) and other immune-mediated diseases, placing alongside or even replacing conventional and biological drugs. JAKi are characterized by a novel mechanism of action, consisting of the intracellular interruption of the JAK-STAT pathway crucially involved in the immune response. The aim of this narrative review is to globally report the most relevant pharmacological features and clinical outcomes of the developed and incoming JAKi for RA, based on the available preclinical and clinical evidence. A total of 219 papers, including narrative and systematic reviews, randomized controlled trials (RCTs), observational studies, case reports, guidelines, and drug factsheets, were selected. The efficacy and safety profile of both the first generation JAKi (baricitinib and tofacitinib) and the second generation JAKi (upadacitinib, filgotinib, peficitinib, decernotinib and itacitinib) were compared and discussed. Results from RCTs and real-life data are encouraging and outline a rapid onset of the pharmacologic effects, which are maintained during the time. Their efficacy and safety profile are comparable or superior to those of biologic agents and JAKi proved to be efficacious when given as monotherapy. Finally, the manufacturing of JAKi is relatively easier and cheaper than that of biologics, thus increasing the number of compounds being formulated and tested for clinical use.

JAK inhibitors and infections risk: focus on herpes zoster

Currently, there is a growing interest in Janus kinase (JAK) intracellular signalling since targeted inhibitors against these pathways are proving effective in the treatment of a range of immune-mediated diseases, such as rheumatoid arthritis (RA), psoriasis, psoriatic arthritis (PsA), inflammatory bowel disease and atopic dermatitis. In particular, post marketing experience and the increasing development of new pharmacological inhibitors of broad and increasingly selective JAK pathways provide new insights into the JAK pathway role in viral infections as well as their pathogenic role in immune-mediated inflammatory diseases. Herein we provide an overview of the biological role of JAK signalling and its role in immunity against viruses, with particular regard to herpes zoster reactivation. Thereafter, we will discuss the evidence currently available on the principal JAK inhibitors and their association with viral infections.

Systematic review on tuberculosis risk in patients with rheumatoid arthritis receiving inhibitors of Janus Kinases

INTRODUCTION

Janus kinases inhibitors (anti-JAKs), including tofacitinib, baricitinib, upadacitinib, and filgotinib, represent a new class of synthetic targeted drugs for the treatment of rheumatoid arthritis (RA). In this review, the risk of active tuberculosis (TB) occurrence in patients receiving anti-JAKs was assessed. The literature on this topic, updated to 29 February 2020 was reviewed. Overall, 40 reports (22 tofacitinib, 10 baricitinib, 5 upadacitinib, 3 filgotinib) were examined. A low frequency, not exceeding 0.25%, of active TB cases in patients were exposed to anti-JAKs. Only 1 of 89 recorded cases in tofactinib and baricitinib exposure occurred in countries at intermediate or high TB risk, and most of the cases probably were due to first mycobacterium tuberculosis (Mtb) exposure. Although no cases were observed in patients receiving upadacitinib and filgotinib, long-term trials and data from real-life are required to more precisely address the TB risk associated with the two drugs.

AREAS COVERED

Discussion on the TB risk associated with anti-JAKs, and on the need for accurate evaluation of host-related risk factors in high risk countries.

EXPERT OPINION

Available data on anti-JAKs suggest a negligible risk of active TB occurrence in low endemic areas.

Evaluating upadacitinib for the treatment of rheumatoid arthritis

INTRODUCTION

The introduction of JAKs inhibitors for the treatment of rheumatoid arthritis represents a promising new era in the management of the disease. New compounds under investigation, like upadacitinib, with greater selectivity for JAK1 inhibition have recently been approved for the treatment of adults with moderately to severely active rheumatoid arthritis who have had an inadequate response or intolerance to conventional synthetic disease-modifying antirheumatic drugs.

AREAS COVERED

Herein, the authors review the pharmacological data, the therapeutic efficacy, and safety data of upadacitinib before providing the reader with their critical evaluation and future perspectives.

EXPERT OPINION

Upadacitinib was able to accomplish all the primary and secondary end points in most of the trials, with a safety profile that is similar to the other JAK inhibitors. It has also demonstrated superiority over a tumor necrosis factor inhibitor and data on new indications is also favorable. Upadacitinib is a promising new drug for the treatment of rheumatoid arthritis.

GLOSSARY

Adalimumab: ADA; American College of Rheumatology: ACR; Assessment of Spondylarthritis International Society 40: ASAS40; Ankylosis Spondylitis: AS; Area under the Curve: AUC; Biological Disease-modifying arthritis drugs: bDMARDs; Clinical disease activity index: CDAI; C Reactive Protein: CRP; Conventional Synthetic Disease-modifying arthritis drugs: csDMARDs; Deep Venous Thrombosis: DVT; Disease arthritis score: DAS.

Peficitinib for the treatment of rheumatoid arthritis: an overview from clinical trials

INTRODUCTION

The treatment of rheumatoid arthritis (RA), a chronic, systemic, autoimmune disease, has been greatly advanced by the introduction of biologic disease-modifying antirheumatic drugs (DMARDs); however, many patients still fail to achieve disease remission. Peficitinib, an orally bioavailable inhibitor of the Janus kinase (JAK) receptor family, was approved in Japan in 2019 and Korea in 2020 for the treatment of RA.

AREAS COVERED

This review provides an overview of JAK inhibitors currently marketed or in development; the pharmacodynamics and pharmacokinetics of peficitinib; and the efficacy and safety data for peficitinib from Phase 2b and 3 trials.

EXPERT OPINION

Peficitinib has proven clinical efficacy in Asian patients (Japan, Korea, and Taiwan) with RA who have an inadequate response to conventional DMARDs. In Phase 3 trials, clinical improvements and prevention of joint destruction were demonstrated for both 100 mg and 150 mg once-daily peficitinib versus placebo, and treatment for up to 52 weeks was well tolerated. Safety signals, in particular the increased incidence of herpes zoster-related disease, appeared in line with other JAK inhibitors. Post-launch monitoring will establish the long-term safety and effectiveness of this drug, and further studies are necessary to determine its potential use in non-Asian populations.

The altered gut microbiota of high-purine-induced hyperuricemia rats and its correlation with hyperuricemia

Some studies on the hyperuricemia (HUA) have focused on intestinal bacteria. To better understand the correlation between gut microbiota and HUA, we established a HUA rat model with high-purine diet, and used 16S rRNA genes sequencing to analyze gut microbiota changes in HUA rats. To analyze the potential role played by gut microbiota in HUA, we altered the gut microbiota of HUA rats with antibiotics, and compared the degree of uric acid elevation between HUA and antibiotic-fed HUA rats (Ab+HUA). Finally, we established a recipient rat model, in which we transplanted fecal microbiota of HUA and normal rats into recipient rats. Three weeks later, we compared the uric acid content of recipient rats. As a result, the diversity and abundance of the gut microbiota had changed in HUA rats. The Ab-fed HUA rats had significantly lower uric acid content compared to the HUA rats, and gut microbiota from HUA rats increased uric acid content of recipient rats. The genera Vallitalea, Christensenella and Insolitispirillum may associate with HUA. Our findings highlight the association between gut microbiota and HUA, and the potential role played by gut microbiota in HUA. We hope that this finding will promote the isolation and culture of HUA-related bacteria and orient HUA-related studies from being correlational to mechanistic. These steps will therefore make it possible for us to treat HUA using gut microbiota as the target.

The Promise of JAK Inhibitors for Treatment of Sarcoidosis and Other Inflammatory Disorders with Macrophage Activation: A Review of the Literature

Certain inflammatory disorders are characterized by macrophage activation and accumulation in tissue; sometimes leading to the formation of granulomas, as in sarcoidosis. These disorders are often difficult to treat and more effective, molecularly targeted therapies are needed. Recent work has shown that overproduction of inflammatory cytokines, such as interferon gamma (IFN-γ) leading to constitutive activation of the JAK-STAT pathway may be a conserved feature of these disorders. Use of JAK inhibitors, which can block these signals, has resulted in dramatic improvement in several patients with sarcoidosis. JAK inhibitors also appear to have activity in other inflammatory disorders with macrophage activation including hemophagocytic lymphohistiocystosis, Crohn's disease, granuloma annulare, and necrobiosis lipoidica. Here, we review the role of JAK dependent cytokines in macrophage activation and granuloma formation and the clinical evidence supporting the use of JAK inhibition in these disorders. Ongoing efforts to evaluate role of JAK inhibitors in these disorders is also discussed.

Inhaled Janus Kinase (JAK) inhibitors for the treatment of asthma

Multiple asthma-relevant cytokines including IL-4, IL-5, IL-13, and TSLP depend upon JAKs for signaling. JAK inhibition may, therefore, offer a novel intervention strategy for patients with disease refractory to current standards of care. Multiple systemically delivered JAK inhibitors have been approved for human use or are under clinical evaluation in autoimmune diseases such as rheumatoid arthritis. However, the on-target side effect profiles of these agents are likely not tolerable for many asthmatic patients. Limiting JAK inhibition to the lung is expected to improve therapeutic index relative to systemic inhibition. Thus, inhaled JAK inhibitors with lung-restricted exposure are of high interest as potential treatments for asthma.

Pathogenic and Therapeutic Relevance of JAK/STAT Signaling in Systemic Lupus Erythematosus: Integration of Distinct Inflammatory Pathways and the Prospect of Their Inhibition with an Oral Agent

Four Janus kinases (JAKs) (JAK1, JAK2, JAK3, TYK2) and seven signal transducers and activators of transcription (STATs) (STAT1, STAT2, STAT3, STAT4, STAT5A, STAT5B, STAT6) mediate the signal transduction of more than 50 cytokines and growth factors in many different cell types. Located intracellularly and downstream of cytokine receptors, JAKs integrate and balance the actions of various signaling pathways. With distinct panels of STAT-sensitive genes in different tissues, this highly heterogeneous system has broad in vivo functions playing a crucial role in the immune system. Thus, the JAK/STAT pathway is critical for resisting infection, maintaining immune tolerance, and enforcing barrier functions and immune surveillance against cancer. Breakdowns of this system and/or increased signal transduction may lead to autoimmunity and other diseases. Accordingly, the recent development and approval of the first small synthetic molecules targeting JAK molecules have opened new therapeutic avenues of potentially broad therapeutic relevance. Extensive data are now available regarding the JAK/STAT pathway in rheumatoid arthritis. Dysregulation of the cytokines is also a hallmark of systemic lupus erythematosus (SLE), and targeting the JAK/STAT proteins allows simultaneous suppression of multiple cytokines. Evidence from in vitro studies and animal models supports a pivotal role also in the pathogenesis of cutaneous lupus and SLE. This has important therapeutic implications, given the current paucity of targeted therapies especially in the latter. Herein, we summarize the currently available literature in experimental SLE, which has led to the recent promising Phase II clinical trial of a JAK inhibitor.

Current Therapeutic Options in the Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation of the joints. Untreated RA leads to a destruction of joints through the erosion of cartilage and bone. The loss of physical function is the consequence. Early treatment is important to control disease activity and to prevent joint destruction. Nowadays, different classes of drugs with different modes of action are available to control the inflammation and to achieve remission. In this review, we want to discuss differences and similarities of these different drugs.

Clinical efficacy of launched JAK inhibitors in rheumatoid arthritis

Tofacitinib and baricitinib are the first orally available, small-molecule inhibitors of Janus kinase (JAK) enzymes to be approved for the treatment of RA. Tofacitinib is a selective JAK1, 3 inhibitor with less activity against JAK2 and TYK2 and baricitinib is a selective, oral JAK1, 2 inhibitor with moderate activity against TYK2 and significantly less activity against JAK3. Both drugs have undergone extensive phase III clinical trials in RA and demonstrated rapid improvements in disease activity, function and patient-reported outcomes as well as disease modification. Tofacitinib 5 mg bd, was approved by the Federal Drug Administration in 2012 for the treatment of RA in patients who are intolerant or unresponsive to MTX. An extended release formulation for the treatment of RA was approved by Federal Drug Administration in 2016. In 2017 the European Medicines Agency approved tofacitinib 5 mg bd in combination with MTX and baricitinib 4 mg and 2 mg once daily for the treatment of moderate to severe active RA in adult patients who are intolerant or unresponsive to one or more conventional synthetic DMARDs.