JAK3 inhibition significantly attenuates psoriasiform skin inflammation in CD18 mutant PL/J mice

Tofacitinib treatment for plaque psoriasis and psoriatic arthritis: A meta-analysis of randomised controlled trials

Objectives Tofacitinib is used as an oral Janus-associated kinase (JAK) inhibitor acting on JAK1 and JAK3, in treating psoriatic disease. However, there is still no consensus on the optimal dosage and duration of tofacitinib. In this study, we aimed to evaluate the effects of tofacitinib in treating psoriatic disease. Methods A literature search was done utilising Cochrane library, Medline, EMBASE, Wiley Online library, Web of Science and BIOSIS Previews through December 18, 2022. We performed a meta-analysis of published original studies to assess the impact of tofacitinib in plaque psoriasis or psoriatic arthritis therapy based on seven randomised controlled trials (RCTs) involving 2,672 patients (receiving tofacitinib) and 853 controls (receiving placebo). Results Compared with placebo, the treatment of 5 mg twice-daily (BID) tofacitinib for 12 weeks is sufficient to significantly alleviate the main clinical manifestations of psoriasis [≥75% decrease in Psoriasis Area and Severity Index score (PASI 75): Risk ratio (RR)=4.38 (95% Confidence interval (CI) 2.51 to 7.64); ≥90% decrease in PASI score (PASI 90): RR=21.68 (95% CI 4.20 to 111.85); Physician's Global Assessment of 'clear' or 'almost clear' (PGA 0/1): RR=3.93 (95%CI 3.03 to 5.09)]. Interestingly, there was no significant difference in improvement in PGA 0/1 with 5 mg BID tofacitinib given for 16 weeks when compared with 5 mg BID tofacitinib for 12 weeks [RR=1.11 (95%CI 0.98 to 1.25)]. Additionally, the 5 mg BID tofacitinib for 16 weeks treatment schedule significantly increased the incidence of upper respiratory tract infection (URTI) [RR=1.89 (95%CI 1.06 to 3.38)] as compared to 5 mg BID tofacitinib for 12 weeks treatment schedule [RR=1.15 (95%CI 0.60 to 2.20)]. Conclusion The 5 mg BID tofacitinib for 12 weeks treatment significantly improved psoriasis without causing too many specific adverse events. This indicated that tofacitinib is an effective treatment plan for psoriatic disease by reasonably controlling dosage and dosing time.

Quantitative analysis of JAK/STAT signaling pathway in patients of inflammatory skin disorders

BACKGROUND

Inflammatory skin diseases (ISDs), are characterized by dysregulated activation of innate and adaptive immune systems, with inflammatory cytokines playing a crucial role in their pathogenesis.

OBJECTIVES

This study aimed to investigate the involvement of Janus kinase/signal transduction and activator of transcription (JAK/STAT) signaling pathway in the pathogenesis of ISDs.

METHODS

The study analyzed a total of 117 skin biopsies, comprising 31 from pyoderma gangrenosum (PG), 25 from hidradenitis suppurativa (HS), 35 from psoriasis patients, and 26 from control subjects. To assess the expression levels of JAK/STAT pathway components, immunohistochemical staining was performed on both the dermal and epidermal layers of the skin. The Histo score (H score) was utilized as the immunoexpression score to evaluate the staining intensity.

RESULTS

The results indicated that all components of the JAK/STAT signaling pathway, except JAK2 and STAT6 in PG, JAK1, STAT4, and STAT6 in HS, and JAK1 in psoriasis, were overexpressed in the dermal skin compared to the control group (p < 0.05). Psoriatic skin had higher expression of STAT6 than both PG and HS and higher expression of JAK2 than PG (p < 0.05). Additionally, HS biopsies had higher expression of JAK2 and STAT6 compared to PG (p < 0.05). JAK1 expression was higher in PG than in HS, psoriasis, and the control group (mean H score was 265.8, 184.8, 191.4, and 113.1, p < 0.05, respectively).

CONCLUSIONS

This study provides new insights into the potential contribution of the JAK/STAT pathway to the pathogenesis of ISDs. The findings suggest that targeting this pathway could be a promising therapeutic strategy for treating these disorders.

Selective Inhibitors of Janus Kinase 3 Modify Responses to Lipopolysaccharides by Increasing the Interleukin-10-to-Tumor Necrosis Factor α Ratio

Janus kinase (JAK) inhibitors act at low doses (e.g., tofacitinib, 0.2-0.4 μmol/kg bid) in clinical use, suggesting an efficient underlying mode of action. We hypothesized that their effectiveness is due to their ability to raise the ratio of IL-10 to TNFα. Unlike other JAK isoforms, JAK3 is expressed mainly in hematopoietic cells and is essential for immune function. We used JAK3 selective inhibitors with preferential distribution to immune cells. Inhibition of JAK3 in human leukocytes reduced TNFα and IL-6 but maintained levels of IL-10, while pan-JAK inhibitors increased TNFα, IL-6, and IL-10. JAK1 is required for IL-10 receptor signaling, which suggests that, at exposure above the IC50 (55 nM for tofacitinib on JAK1), there is less feedback control of TNFα levels. This leads to self-limiting effects of JAK1 inhibitors and could place an upper limit on appropriate doses. In vivo, treating mice with JAK3 inhibitors before LPS administration decreased plasma TNFα and increased IL-10 above vehicle levels, suggesting that JAK3 inhibition may limit TNFα release by increasing IL-10 while leaving the IL-10 receptor functional. This mechanism should have general utility in controlling autoimmune diseases and can be conveniently observed by measuring the ratio of IL-10 to TNFα. In summary, our targeted, "leukotropic" inhibitors more effectively increased IL-10/TNFα ratios than unselective control compounds and could, therefore, be ideal for autoimmune therapy.

Treating psoriasis in the elderly: biologics and small molecules

INTRODUCTION

Psoriasis prevalence in the elderly is growing. It is estimated that 15% of elderly psoriasis patients suffer from moderate-to-severe disease, thus requiring systemic treatments. However, conventional systemic agents' use is limited due to contraindications and drug-interactions. Conversely, biologics and small molecules seem to be a valuable option, although the geriatric psoriasis population is frequently excluded from trials and shared guidelines are lacking.

AREAS COVERED

Relevant English literature (trials, real-life studies, case series, and reviews) regarding biologics and/or small molecules in the elderly were searched for up to January 17, 2022.

EXPERT OPINION

Treatment of moderate-to-severe psoriasis in the elderly may be challenging due to multiple comorbidities, polypharmacy, and increased risk of infections and cancers. However, new targeted therapies offer the possibility to perform a tailored-tail management, considering comorbidities, drug-interactions, and frailties which characterize this class of patients. Several real-world data support biologics and small molecules' efficacy and safety in the elderly with mainly no significant difference as compared to young adults. Elderly psoriasis patients' expectations are as high as those of their younger counterparts. Hence, they deserve the best therapeutic options according to their peculiarities for a long-term psoriasis remission and an improved quality of life.

Inside-out and outside-in organotypic normal human skin culture: JAK-STAT pathway is activated after pro-inflammatory psoriatic cytokine exposure

The Janus kinases-signal transducers and activators of transcription (JAK-STAT) signalling pathway are a pleiotropic cascade that involves ligands such as cytokines, hormones, and growth factors. Among cytokines, interleukin (IL)-17, IL-22, IL-23, and tumour necrosis factor (TNF)-alpha play a pivotal role in psoriasis. We aimed at investigating in an organotypic experimental model of normal human skin (n = 7 women between 20-40 years old, non-smokers) the early, direct, and specific effects of IL-17, IL-22, IL-23, TNF-alpha and a combination of the four cytokines (Mix) on the JAK-STAT/pathway. The expression of the psoriatic marker keratin (K) 17 was analyzed by immunofluorescence and molecular techniques after exposure to IL-23 or Mix. The Mix elicited a strong K17 up-regulation in keratinocytes at 72 h, reinforcing the hypothesis of a synergistic effect of different cytokines. High levels of JAK1 and STAT3 activation were detected, suggesting the involvement of JAK1/STAT3 pathway in the upregulation of K17. As the present study in an organotypic model of human skin reports a variable expression of JAK-STAT upon different cytokine stimuli and most of the JAK inhibitors for the psoriasis treatment have proven to have a clinical efficacy, these observations have a relevance to better understand the mechanisms of JAK-inhibitors in the skin.

Evaluation of pregnancy-associated plasma protein-A and some inflammation markers for atherosclerosis in psoriasis patients

Introduction

Psoriasis is a common, chronic inflammatory disease of the skin. Although its relationship with cardiovascular risk factors is one of the main causes of mortality, the association between psoriasis and cardiovascular events is controversial.

Aim

The aim of this study is to measure the levels of hs-CRP and pregnancy-associated plasma protein-A (PAPP-A) related to atherosclerosis in patients with moderate-severe psoriasis and to evaluate their possible association with disease severity.

Material and methods

This study included 45 moderate-severe psoriasis patients without additional risk factors for cardiovascular disease and 45 healthy individuals as a control group.

Results

Serum PAPP-A levels in both groups were given as two different variables, detectable and non- detectable, based on a value of 0.004 U/lL. When PAPP-A levels were compared, there was no statistically significant difference between the groups.

Conclusions

The use of the PAPP-A test in the evaluation of early-stage atherosclerosis in moderate-severe psoriasis patients who do not have additional risk factors for cardiovascular diseases may not be sufficient.

The efficacy and safety of JAK inhibitors for atopic dermatitis: a systematic review and meta-analysis

BACKGROUND

Atopic dermatitis (AD) is one of the serious global problems. There were wide concerns about whether Janus kinase (JAK) inhibitor was an alternative treatment for AD.

METHOD

Eight databases were searched from the earliest publication date available to January 2, 2021. We included randomized controlled trials comparing JAK inhibitors with control treatment for AD. Data were pooled using Stata.14 software and performed as mean differences (MD) and risk ratios (RR) with 95% CIs. We did subgroup analysis based on specific outcomes.

RESULTS

A total of studies, ten randomized controlled trials, with 2583 patients were included in the final synthesis. This meta-analysis showed JAK inhibitor resulted in significant improvement on EASI total score (MD = -0.31; 95%CI, -0.46 to -0.17; p = .000; I² = 90.0%, p = .000) and pruritus numerical rating scale (NRS) score (MD = -1.15; 95%CI, -1.48 to -0.83; p = .000; I² = 95.9%, p = .000), without the higher risk of total adverse effects (RR = 1.02; 95%CI, 0.90-1.16; p = .745; I² =27.9%, p = .206).

CONCLUSIONS

JAK inhibitor was a promising option for atopic dermatitis. More data and surveillance will be needed to identify efficacy, safety, and the risk of adverse effects.

Pharmacophore modeling and 3D-QSAR studies of 2,4-disubstituted pyrimidine derivatives as Janus kinase 3 inhibitors

A robust pharmacophore model was developed and the structure-activity relationship was analyzed using 71 pyrimidine derivatives reported for covalent Janus Kinase 3 (JAK3) inhibition. Pharmacophore modeling developed a five featured pharmacophore: one H-bond acceptor, two H-bond donors, one hydrophobic, and one aromatic ring features. The atom-based three-dimensional QSAR models with statistical significance were generated using the training set of 52 compounds. The excellent predictive correlation coefficients were obtained for 3D models determined using a test set of 19 molecules. The generated QSAR model implies that the hydrophobic character is important for the JAK3 inhibitory activity of these compounds. Additionally, electron-withdrawing and hydrogen bond donor groups at specific positions positively contribute to the JAK3 inhibition potency. These results provided essential three-dimensional structural requirements and the crucial binding features of 2,4-disubstituted pyrimidine derivatives, which may direct for the design and discovery of novel potent JAK3 inhibitors.

Tofacitinib in Pediatric Psoriasis: An Open-Label Trial to Study Its Safety and Efficacy in Children

Introduction: Psoriasis is a chronic, multifactorial, inflammatory disorder, with an estimated prevalence of 0.71% in children. The commonly used therapeutic agents target the underlying inflammation. Tofacitinib has demonstrated efficacy in adult psoriasis. Aim: To study the efficacy, safety, and tolerability of tofacitinib in pediatric patients with moderate to severe chronic plaque psoriasis. Methods: The study included children aged between 8 and 17 years, with moderate to severe psoriasis, given tofacitinib 5 mg orally twice daily for at least 36 weeks. The clinical response was estimated using the Psoriasis Area and Severity Index (PASI) score, Physician’s Global Assessment (PGA), and the Children’s Dermatology Life Quality Index (CDLQI). The incidence and severity of adverse events (AEs) were meticulously recorded in each case. Results: A total of 47 patients, with a median age of 12.3 years, completed the study. At week 12, 55.32% achieved PASI 75, and 70.21% at week 36. PGA of clear or almost clear responses at week 12 were 59.57 and 65.96%, ­respectfully, at week 36. Relatively few and mostly minor ­adverse effects were noted. No severe AEs were reported. ­Conclusion: The treatment with tofacitinib was safe and well tolerated, and led to significant improvement of their disease and quality of life as reflected in CDLQI scores. However, the results need to be validated in larger multicenter trials.

Targeting the Janus Kinase Family in Autoimmune Skin Diseases

Autoimmune skin diseases are characterized by significant local and systemic inflammation that is largely mediated by the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway. Advanced understanding of this pathway has led to the development of targeted inhibitors of Janus kinases (JAKinibs). As a class, JAK inhibitors effectively treat a multitude of hematologic and inflammatory diseases. Growing evidence suggests that JAK inhibitors are efficacious in atopic dermatitis, alopecia areata, psoriasis, and vitiligo. Additional evidence suggests that JAK inhibition might be broadly useful in dermatology, with early reports of efficacy in several other conditions. JAK inhibitors can be administered orally or used topically and represent a promising new class of medications. Here we review the evolving data on the role of the JAK-STAT pathway in inflammatory dermatoses and the potential therapeutic benefit of JAK-STAT antagonism.

Efficacy and safety of tofacitinib for the treatment of chronic plaque psoriasis: a systematic review and meta-analysis

Background

Tofacitinib is an oral Janus kinase (JAK) inhibitor that targets JAK1 and JAK3, and thus regulates immune response. Therefore, tofacitinib is used to treat immune-mediated inflammatory diseases such as chronic plaque psoriasis. The objective of this study was to systematically assess the efficacy and safety of tofacitinib in treating chronic plaque psoriasis.

Objective

To systematically review the efficacy and safety of tofacitinib in the treatment of chronic plaque psoriasis, we performed a meta-analysis to evaluate the efficacy and safety of tofacitinib in patients with chronic plaque psoriasis.

Methods

Databases including PubMed, Embase, and The Cochrane Library were searched for randomized controlled trials about the efficacy and safety of tofacitinib in treating chronic plaque psoriasis from inception to August 2017 (PROSPERO Code No: CRD42017076587).

Results

Six articles (seven randomized controlled trial studies) involving 3743 patients were included. The meta-analysis results showed that for efficacy, tofacitinib (5 mg or 10 mg) compared with placebo can significantly improve the Physician’s Global Assessment response, PASI75, and PASI90 after treatment. For safety, the incidence of adverse reactions was statistically significantly higher for tofacitinib compared with placebo.

Conclusion

Treatment of chronic plaque psoriasis with tofacitinib is effective, but there may be more adverse reactions.

Protein biomarker for psoriasis: A systematic review on their role in the pathomechanism, diagnosis, potential targets and treatment of psoriasis

Psoriasis is defined as a long-lasting multifactorial inflammatory autoimmune skin condition precisely characterized by delimited, erythematic papules with adherent shiny scales. The conditions are led by hyperproliferative responses of epidermis due to hyperactivation and immature keratinocytes production. The psoriatic skin consists of the thickened epidermal layer, in concurrence with inflammatory exudates in the dermis mainly of dendritic cells, neutrophils, T cells, and macrophages, contributing to the distinct manifestation of psoriatic lesions. It consents to multifaceted and discrete pathology due to the genetic and immunological alteration resulting from abnormal expression of various regulatory and structural proteins. These proteins are associated with various cellular and sub-cellular activities. Therefore, the presence of protein in a pathological cellular environment in the psoriatic lesions as well as in serum could be a great avenue for the insight of pathomechanism, anticipation and diagnosis of psoriasis. Research of protein biomarker in psoriasis is yet a developing realm to be explored by both fundamental and clinical researchers. This review is an attempt to assimilate the current discoveries and revelations of different proteins as a biomarker and their importance in pathogenesis, diagnosis, treatment, and anticipation of both the inflammatory and other dermatological aspects of psoriasis.

Psoriasis Treatments: A Review of the Current Research Pipeline

Psoriasis treatment is aimed at suppressing skin lesions and preventing relapses. Although in the last decade biological therapies have revolutionized the pharmacologic treatment armamentarium for psoriasis, many patients are still inadequately controlled with currently available therapeutics. An advanced understanding of the immunopathogensis of psoriasis has led to development of new drugs that refine existing treatments or target novel molecular and immunologic pathways. Here we review the most promising topical, oral, and injectable psoriasis treatments in the research pipeline, including agents that target cytokines interleukin (IL)-12/23, tumor necrosis factor-α, IL-20, IL-17, IL-22, inhibitors of calcineurin, phosphodiesterase type 4, protein kinase C, Janus kinase, p38 kinase, purine nucleotide phosphorylase, adenosine receptor agonists, and recombinant chaperonin protein. These targeted therapeutics offer the potential for greater clinical efficacy and less toxicity than traditional agents. As the number of treatment options continues to expand, clinicians will have more diverse opportunities to help patients achieve better psoriasis control.

Computerized planimetry to assess clinical responsiveness in a phase II randomized trial of topical R333 for discoid lupus erythematosus

BACKGROUND

R333 is a topical janus kinase and spleen tyrosine kinase inhibitor being evaluated for discoid lupus erythematosus (DLE) treatment. There is no validated measure to assess the area of active DLE lesions.

OBJECTIVES

To evaluate R333 efficacy and assess a technique to measure responsiveness.

METHODS

Fifty-four patients with DLE were randomized in a double-blind design to R333 or placebo. Primary end point was the proportion of patients achieving ≥ 50% decrease in erythema and scale based on lesional Cutaneous Lupus Erythematosus Disease Area and Severity Index^TM for all treated lesions at week 4. Two-dimensional (2D) area measurements for each lesion were recorded at baseline and weeks 1-6. Eighty-eight photographs (44 pre- and 44 post-treatment) were obtained from the trial and change in size of active areas was analysed by computerized planimetry and physician-assessed area change (PAAC).

RESULTS

Thirty-six patients were randomized to R333 and 18 patients were randomized to placebo. Primary end point was not achieved. There was a strong association between lesion activity and physician global assessment (P < 0·001). Photos of 42 patients assessed by computerized planimetry demonstrated excellent inter- and intra-rater reliability. Area change by computerized planimetry showed a strong correlation with PAAC (Spearman r = 0·72). Area change by 2D measurements showed a weak correlation with PAAC (Spearman r = 0·29).

CONCLUSIONS

Four weeks of R333 treatment did not result in significant improvement in lesion activity. Lesion activity and area change using computerized planimetry are better determinants of responsiveness than area change using 2D measurements.

STAT3: The art of multi-tasking of metabolic and immune functions in obesity

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that has recently attracted increased attention. Accumulating studies have demonstrated that STAT3 plays an important role in various diseases, such as cancer and ischemic injury. In light of the distinctive effects of STAT3 on the regulation of metabolism and immune responses, we present the elaborate network of STAT3 in obesity. In this review, we first introduce the general background of STAT3, including a discussion regarding the STAT family and the characterization and regulation of STAT3. Then, we describe the STAT3 signaling network and its pathophysiological roles in lipid and glucose metabolism and immune function. Finally, we highlight the research progress regarding STAT3 in obesity. The information presented here may be useful for the design of future studies and may highlight the potential of STAT3 as a future therapeutic target for obesity.

Efficacy and safety of tofacitinib for moderate-to-severe plaque psoriasis: a systematic review and meta-analysis of randomized controlled trials

The effects of tofacitinib in treating moderate-to-severe plaque psoriasis were unclear. We aimed to assess the effects of tofacitinib in treating moderate-to-severe plaque psoriasis. We searched PubMed, Cochrane Central Register of Controlled Trials and EMBASE for relevant randomized controlled trials (RCTs) and conducted a systematic review and meta-analysis. Four RCTs with 2724 participants were included. Compared to placebo, tofacitinib significantly improved psoriasis {≥75% reduction in the Psoriasis Area and Severity Index score: 5 mg BID: risk difference (RD) 0.32 [95% confidence interval (CI) 0.28-0.35], 10 mg BID: RD 0.51 (95% CI 0.43-0.58); ≥90% reduction in the Psoriasis Area and Severity Index score: 5 mg BID: RD 0.19 (95% CI 0.17-0.22), 10 mg BID: RD 0.36 (95% CI 0.31-0.42); Physician's Global Assessment 0/1: 5 mg BID: RD 0.31 (95% CI 0.27-0.35), 10 mg BID: RD 0.48 (95% CI 0.44-0.53)} and participants' life quality [Dermatology Life Quality Index 0/1: 5 mg BID: RD 0.24 (95% CI 0.20-0.2), 10 mg BID: RD 0.36 (95% CI 0.33-0.40)]. Tofacitinib was associated with an increase in minor adverse events [upper respiratory tract infection: 5 mg BID: RD 0.02 (95% CI 0.00-0.03), 10 mg BID: RD 0.02 (95% CI 0.00-0.04); hypercholesterolaemia: 5 mg BID: RD 0.02 (95% CI 0.01-0.04), 10 mg BID: RD 0.02 (95% CI 0.01-0.04)]. In conclusion, tofacitinib may be a treatment option for moderate-to-severe plaque psoriasis that is unresponsive to other therapies and patients who are intolerable to other therapies or prefer oral medications.

Using Genome Sequence to Enable the Design of Medicines and Chemical Probes

Rapid progress in genome sequencing technology has put us firmly into a postgenomic era. A key challenge in biomedical research is harnessing genome sequence to fulfill the promise of personalized medicine. This Review describes how genome sequencing has enabled the identification of disease-causing biomolecules and how these data have been converted into chemical probes of function, preclinical lead modalities, and ultimately U.S. Food and Drug Administration (FDA)-approved drugs. In particular, we focus on the use of oligonucleotide-based modalities to target disease-causing RNAs; small molecules that target DNA, RNA, or protein; the rational repurposing of known therapeutic modalities; and the advantages of pharmacogenetics. Lastly, we discuss the remaining challenges and opportunities in the direct utilization of genome sequence to enable design of medicines.

STAT2 is involved in the pathogenesis of psoriasis by promoting CXCL11 and CCL5 production by keratinocytes

The JAK/STAT signaling pathway is suggested to play an important role in the pathogenesis of psoriasis, and recently JAK/STAT inhibitors have shown promising results in psoriasis treatment. The present study aimed to characterize the role of STAT2 in psoriasis. We demonstrated an increased expression of STAT2 and an increased level of phosphorylated/activated STAT2 in lesional compared with nonlesional psoriatic skin. Gene silencing of STAT2 by siRNA in human keratinocytes revealed that upon IFNα stimulation CXCL11 and CCL5 were the only two cytokines, among 102 analyzed, found to be regulated through a STAT2-dependent mechanism. Moreover, the regulation of CXCL11 and CCL5 depended on IRF9, but not on STAT1 and STAT6. The CXCL11 and CCL5 expression was increased in lesional compared with nonlesional psoriatic skin, and analysis demonstrated positive correlation between the expression of CXCL11 and IFNγ and between the expression of CCL5 and IFNγ in lesional psoriatic skin. In contrast, no correlation between the expression of CXCL11 and IL-17A and the expression of CCL5 and IL-17A in lesional psoriatic skin was found. Our data suggest that STAT2 plays a role in the psoriasis pathogenesis by regulating the expression of CXCL11 and CCL5, and thereby attracting IFNγ-producing immune cells to the skin.

Tofacitinib for the treatment of psoriasis

INTRODUCTION

The identification of a number of psoriasis-susceptibility genes and a better understanding of the pathogenesis of the intracellular metabolic pathways, have generated new perspectives on psoriasis treatment, in particular new compounds that inhibit certain intracellular proteins involved in the immune response. In contrast to biologic agents, these compounds block intracellular targets such as transcriptional factors or enzymes.

AREAS COVERED

Tofacitinib is a small molecule that acts as a reversible, competitive inhibitor of ATP in the ATP binding site of JAK proteins, determining their inactivation, thus prevents the downstream activation of the STAT proteins, which are then unable to up-regulate the pro-inflammatory genes implicated in psoriasis. The authors present an overview of Phases I - III clinical trials of tofacitinib for psoriasis based on peer-reviewed literature.

EXPERT OPINION

In clinical practice, it is important to assess the response of psoriasis to tofacitinib and identify possible clinical, genetic, and immune biomarkers to predict the response. Comorbidities associated with psoriasis, in particular metabolic syndrome and obesity, are also an important aspect of using tofacitinib in clinical practice. There are some evidences that a drug such as tofacitinib could be used to improve not only psoriasis, but also some of its important comorbidities.

Psoriatic inflammation enhances allergic airway inflammation through IL-23/STAT3 signaling in a murine model

Psoriasis is an autoimmune inflammatory skin disease characterized by activated IL-23/STAT3/Th17 axis. Recently psoriatic inflammation has been shown to be associated with asthma. However, no study has previously explored how psoriatic inflammation affects airway inflammation. Therefore, this study investigated the effect of imiquimod (IMQ)-induced psoriatic inflammation on cockroach extract (CE)-induced airway inflammation in murine models. Mice were subjected to topical and intranasal administration of IMQ and CE to develop psoriatic and airway inflammation respectively. Various analyses in lung/spleen related to inflammation, Th17/Th2/Th1 cell immune responses, and their signature cytokines/transcription factors were carried out. Psoriatic inflammation in allergic mice was associated with increased airway inflammation with concurrent increase in Th2/Th17 cells/signature cytokines/transcription factors. Splenic CD4+ T and CD11c+ dendritic cells in psoriatic mice had increased STAT3/RORC and IL-23 mRNA expression respectively. This led us to explore the effect of systemic IL-23/STAT3 signaling on airway inflammation. Topical application of STA-21, a small molecule STAT3 inhibitor significantly reduced airway inflammation in allergic mice having psoriatic inflammation. On the other hand, adoptive transfer of IL-23-treated splenic CD4+ T cells from allergic mice into naive recipient mice produced mixed neutrophilic/eosinophilic airway inflammation similar to allergic mice with psoriatic inflammation. Our data suggest that systemic IL-23/STAT3 axis is responsible for enhanced airway inflammation during psoriasis. The current study also suggests that only anti-asthma therapy may not be sufficient to alleviate airway inflammatory burden in asthmatics with psoriasis.

JAK3 as an Emerging Target for Topical Treatment of Inflammatory Skin Diseases

The recent interest and elucidation of the JAK/STAT signaling pathway created new targets for the treatment of inflammatory skin diseases (ISDs). JAK inhibitors in oral and topical formulations have shown beneficial results in psoriasis and alopecia areata. Patients suffering from other ISDs might also benefit from JAK inhibition. Given the development of specific JAK inhibitors, the expression patterns of JAKs in different ISDs needs to be clarified. We aimed to analyze the expression of JAK/STAT family members in a set of prevalent ISDs: psoriasis, lichen planus (LP), cutaneous lupus erythematosus (CLE), atopic dermatitis (AD), pyoderma gangrenosum (PG) and alopecia areata (AA) versus healthy controls for (p)JAK1, (p)JAK2, (p)JAK3, (p)TYK2, pSTAT1, pSTAT2 and pSTAT3. The epidermis carried in all ISDs, except for CLE, a strong JAK3 signature. The dermal infiltrate showed a more diverse expression pattern. JAK1, JAK2 and JAK3 were significantly overexpressed in PG and AD suggesting the need for pan-JAK inhibitors. In contrast, psoriasis and LP showed only JAK1 and JAK3 upregulation, while AA and CLE were characterized by a single dermal JAK signal (pJAK3 and pJAK1, respectively). This indicates that the latter diseases may benefit from more targeted JAK inhibitors. Our in vitro keratinocyte psoriasis model displayed reversal of the psoriatic JAK profile following tofacitinib treatment. This direct interaction with keratinocytes may decrease the need for deep skin penetration of topical JAK inhibitors in order to exert its effects on dermal immune cells. In conclusion, these results point to the important contribution of the JAK/STAT pathway in several ISDs. Considering the epidermal JAK3 expression levels, great interest should go to the investigation of topical JAK3 inhibitors as therapeutic option of ISDs.

JAK inhibitor JTE-052 regulates contact hypersensitivity by downmodulating T cell activation and differentiation

BACKGROUND

Using JAK inhibitors to inhibit cytokine signaling is presumed to be a possible means of treating skin inflammatory disorders such as contact dermatitis.

OBJECTIVE

To clarify the action site of JAK inhibitors in skin inflammatory disorders.

METHODS

We analyzed the mechanism of action of the JAK inhibitor JTE-052 using murine skin inflammation models, including contact hypersensitivity (CHS) and irritant contact dermatitis. Cells isolated from ear tissue or lymph node (LN) were analyzed by flow cytometry. The amounts of cytokines in the culture medium were measured by ELISA or bead array system. Proliferation of LN cells was evaluated by measurement of tritiated thymidine incorporation.

RESULTS

Oral administration of JTE-052 during both sensitization and elicitation phase attenuated CHS, but did not affect croton oil-induced irritant contact dermatitis. JTE-052 potently inhibited T cell proliferation and activation by antigen presentation in vitro, and attenuated skin inflammation in a sensitized-lymphocyte transfer model without suppressing T cell migration. JTE-052 did not affect hapten-induced cutaneous dendritic cell migration into draining lymph nodes or their costimulatory molecule expressions.

CONCLUSION

The JAK inhibitor JTE-052 exerts an inhibitory effect on antigen-specific T cell activation and subsequent inflammation in acquired skin immunity, such as CHS.

Novel Oral Therapies for Psoriasis and Psoriatic Arthritis

Several classes of new oral therapy are in use or in development for the treatment of psoriasis. Despite the high efficacy of biologics, new oral therapies remain important as patients generally prefer this mode of administration and they offer an alternative risk-benefit profile. In this review, we discuss the novel modes of action of these drugs, including modulation of cellular pathways involving diverse targets such as Janus kinase, phosphodiesterase 4, sphingosine 1-phosphate, A3 adenosine receptor and rho-associated kinase 2. We review the available evidence around licensed drugs (apremilast) and drugs that are advanced (tofacitinib) or early (ponesimod, baricitinib, peficitinib, INCB039110, CF101, KD025) in the development pipeline. The key limitations of these oral therapies are their modest efficacy profile (apremilast, ponesimod) and the limitations of their safety profile (tofacitinib, ponesimod), while the evidence for the early pipeline drugs are at phase II level only. Potential niches of current unmet needs include apremilast for patients with concomitant psoriatic arthritis, as combination treatments with biologic therapies, and/or for patients in whom multiple biologic therapies have failed due to immunogenicity and secondary inefficacy. The present knowledge gap regarding these novel drugs includes the need for longer clinical trials or observational studies to evaluate safety, and randomised phase III trials for the early pipeline drugs. We conclude that further research and data are necessary to conclusively establish the role of these agents in the current psoriasis treatment paradigm.

Tofacitinib in ulcerative colitis

Cytokines orchestrate immune and inflammatory responses involved in the pathogenesis of ulcerative colitis (UC). Protein kinases are essential for signal transduction in eukaryotic cells. Janus kinases (JAKs) are a family of protein tyrosine kinases that play a pivotal role in cytokine receptor signaling. Indeed, a major subgroup of cytokines use Type I and II cytokine receptors which signal via the activation of JAKs. Tofacitinib is an oral JAK inhibitor that has been studied in autoimmune pathologies, including UC and rheumatoid arthritis with good overall efficacy and acceptable safety profile. This literature review was performed with the goal of summarizing the knowledge on JAK inhibitors in UC treatment.

Profile of tofacitinib citrate and its potential in the treatment of moderate-to-severe chronic plaque psoriasis

The outlook for patients with psoriasis has improved significantly over the last 10 years with the introduction of targeted therapies. Cytokines exert their effects by activating intracellular signaling and transcription pathways, among which there are Janus kinases (JAKs) and signal transducers and activators of transcription (STAT) pathways. JAKs are intracellular second messengers that are crucial for transmitting extracellular cytokine signals to the cell. JAK inhibition interrupts intracellular signaling and can suppress immune cell activation and inflammation in T-cell-mediated disorders, such as psoriasis. Consequently, JAKs are the subject of intensive research activity, since they represent possible therapeutic targets. Tofacitinib is an orally available compound belonging to a novel category of nonbiologic drugs, the "JAK inhibitors", which target JAKs. Recently, oral and topical formulations of tofacitinib have been demonstrated to be safe and effective for the treatment of plaque psoriasis in randomized clinical trials. In particular, a 10 mg bid dose of tofacitinib was shown to be noninferior to etanercept 50 mg subcutaneously twice weekly. Questions remain unresolved regarding the safety risk beyond the 5 mg bid dose. This review, assessing the available scientific literature, focuses on the profile of tofacitinib, as investigational compound in the treatment of plaque psoriasis. An overview of the efficacy and safety data from randomized clinical trials is provided. In addition, the authors highlight future potential applications of tofacitinib in other skin diseases, in particular alopecia areata and vitiligo.

Tofacitinib versus etanercept or placebo in moderate-to-severe chronic plaque psoriasis: a phase 3 randomised non-inferiority trial

BACKGROUND

New therapeutic options are needed for patients with psoriasis. Tofacitinib, an oral Janus kinase inhibitor, is being investigated as a treatment for moderate-to-severe chronic plaque psoriasis. In this study, we aimed to compare two tofacitinib doses with high-dose etanercept or placebo in this patient population.

METHODS

In this phase 3, randomised, multicentre, double-dummy, placebo-controlled, 12-week, non-inferiority trial, adult patients with chronic stable plaque psoriasis (for ≥12 months) who were candidates for systemic or phototherapy and had a Psoriasis Area and Severity Index (PASI) score of 12 or higher and a Physician's Global Assessment (PGA) of moderate or severe, and had failed to respond to, had a contraindication to, or were intolerant to at least one conventional systemic therapy, were enrolled from 122 investigational dermatology centres worldwide. Eligible patients were randomly assigned in a 3:3:3:1 ratio to receive tofacitinib 5 mg or 10 mg twice daily at about 12 h intervals, etanercept 50 mg subcutaneously twice weekly at about 3-4 day intervals, or placebo. Randomisation was done by a computer-generated randomisation schedule, and all patients and study personnel were masked to treatment assignment. The co-primary endpoints were the proportion of patients at week 12 with at least a 75% reduction in the PASI score from baseline (PASI75 response) and the proportion of patients achieving a PGA score of "clear" or "almost clear" (PGA response), analysed in the full analysis set (all patients who were randomised and received at least one dose of study drug). This study is registered with ClinicalTrials.gov, number NCT01241591.

FINDINGS

Between Nov 29, 2010, and Sept 13, 2012, we enrolled 1106 eligible adult patients with chronic plaque psoriasis and randomly assigned them to the four treatment groups (330 to tofacitinib 5 mg twice daily, 332 to tofacitinib 10 mg twice daily, 336 to etanercept 50 mg twice weekly, and 108 to placebo). Of these patients, 1101 actually received their assigned study medication (329 in the tofactinib 5 mg group, 330 in the tofacitinib 10 mg group, 335 in the etanercept group, and 107 in the placebo group). At week 12, PASI75 responses were recorded in 130 (39·5%) of 329 patients in the tofacitinib 5 mg group, 210 (63·6%) of 330 in the tofacitinib 10 mg group, 197 (58·8%) of 335 in the etanercept group, and six (5·6%) of 107 in the placebo group. A PGA response was achieved by 155 (47·1%) of 329 patients in the tofacitinib 5 mg group, 225 (68·2%) of 330 in the tofacitinib 10 mg group, 222 (66·3%) of 335 in the etanercept group, and 16 (15·0%) of 107 in the placebo group. The rate of adverse events was similar across the four groups, with serious adverse events occurring in seven (2%) of 329 patients in the tofacitinib 5 mg group, five (2%) of 330 in the tofacitinib 10 mg group, seven (2%) of 335 in the etanercept group, and two (2%) of 107 in the placebo group. Three (1%) of 329 patients in the tofacitinib 5 mg group, ten (3%) of 330 in the tofacitinib 10 mg group, 11 (3%) of 335 in the etanercept group, and four (4%) of 107 patients in the placebo group discontinued their assigned treatment because of adverse events.

INTERPRETATION

In patients with moderate-to-severe plaque psoriasis, the 10 mg twice daily dose of tofacitinib was non-inferior to etanercept 50 mg twice weekly and was superior to placebo, but the 5 mg twice daily dose did not show non-inferiority to etanercept 50 mg twice weekly. The adverse event rates over 12 weeks were similar for tofacitinib and etanercept. This study indicates that in the future tofacitinib could provide a convenient and well-tolerated therapeutic option for patients with moderate-to-severe plaque psoriasis.

FUNDING

Pfizer Inc.

A phase 2a randomized, double-blind, placebo-controlled, sequential dose-escalation study to evaluate the efficacy and safety of ASP015K, a novel Janus kinase inhibitor, in patients with moderate-to-severe psoriasis

BACKGROUND

Many immune-mediated disorders, including psoriasis, involve cytokine signalling via Janus kinase (JAK) enzymes. ASP015K (also designated JNJ-54781532), a novel oral JAK inhibitor, has shown moderate selectivity for JAK3 over JAK1 and JAK2 in enzyme assays.

OBJECTIVES

The objective of this study was to evaluate the efficacy and safety of escalating, sequentially grouped, doses of ASP015K vs. placebo in patients with moderate-to-severe psoriasis.

METHODS

This phase 2a multicentre, double-blind, randomized, placebo-controlled study (NCT01096862) enrolled 124 patients with moderate-to-severe plaque psoriasis. Five sequential ASP015K cohorts were enrolled, consisting of four twice-daily dosing groups (10, 25, 60, 100 mg) and one once-daily dosing group (50 mg) for 6 weeks.

RESULTS

The primary efficacy end point [mean change in Psoriasis Area and Severity Index score from baseline to end of treatment (EOT; day 42)] significantly favoured ASP015K (overall treatment effect; P < 0.001) vs. placebo, with greater improvements at higher doses. By EOT, the secondary end points [Physician Static Global Assessment (PSGA) score, percentage of patients achieving PSGA success, and change in percentage, body surface area (BSA)] also improved with ASP015K vs. placebo (P < 0.001 for PSGA score and BSA; P < 0.01 for PSGA success). Epidermal thickness and proliferation decreased from baseline with ASP015K vs. placebo. ASP015K was generally well tolerated, with no serious adverse events (AEs) reported.

CONCLUSIONS

In patients with moderate-to-severe psoriasis, ASP015K demonstrated dose-dependent improvements in clinical and histological measures of severity over 6 weeks of treatment. At all doses, ASP015K was well tolerated, with no reported serious AEs.

Tofacitinib for the treatment of moderate-to-severe psoriasis

Because of the increased knowledge about the underlying cytokine network in psoriasis, selective systemic agents for the treatment of moderate-to-severe psoriasis have been developed during the past decade. The marked upregulation of JAK/STAT pathways in psoriasis and the identification of multiple key mediators in psoriasis pathogenesis that signal through JAK/STAT pathways led to investigation of JAK proteins as potential therapeutic targets for psoriasis treatment. A novel JAK-STAT inhibitor, tofacitinib, has been tested in preclinical studies for the treatment of psoriasis. Considering the satisfactory safety profile and the encouraging efficacy observed in the Phase II and Phase III trials, tofacitinib may represent an important therapeutic to be included into the psoriasis paradigm.

Efficacy and safety of emerging immunotherapies in psoriasis

Psoriasis is a common chronic inflammatory disease of the skin. Current biologic therapies are highly effective in the treatment of psoriasis, transforming the lives of patients with this significantly disabling disease. Advances in the understanding of the immunological pathogenesis of psoriasis have led to the development of new biologic therapies, targeting specific inflammatory cytokines upregulated in psoriasis. These include the IL-17 antagonists, secukinumab, brodalumab and ixekizumab; the IL-23 antagonists, guselkumab and tildrakizumab; and the oral small molecule therapies, tofacitinib and apremilast. Here, we review evidence for the efficacy and safety of these novel psoriasis therapies, providing clinicians with an overview of the next era in immunotherapy for psoriasis.

JAK inhibitors: treatment efficacy and safety profile in patients with psoriasis

Janus kinase (JAK) pathways are key mediators in the immunopathogenesis of psoriasis. Psoriasis treatment has evolved with the advent of targeted therapies, which inhibit specific components of the psoriasis proinflammatory cascade. JAK inhibitors have been studied in early phase trials for psoriasis patients, and the data are promising for these agents as potential treatment options. Tofacitinib, an oral or topically administered JAK1 and JAK3 inhibitor, and ruxolitinib, a topical JAK1 and JAK2 inhibitor, have been most extensively studied in psoriasis, and both improved clinical symptoms of psoriasis. Additional JAK1 or JAK3 inhibitors are being studied in clinical trials. In phase III trials for rheumatoid arthritis, tofacitinib was efficacious in patients with inadequate responses to tumor necrosis factor inhibitors, methotrexate monotherapy, or disease-modifying antirheumatic drugs. The results of phase III trials are pending for these therapies in psoriasis, and these agents may represent important alternatives for patients with inadequate responses to currently available agents. Further investigations with long-term clinical trials are necessary to verify their utility in psoriasis treatment and assess their safety in this patient population.

Discovery and development of Janus kinase (JAK) inhibitors for inflammatory diseases

The Janus kinases (JAKs) are a family of intracellular tyrosine kinases that play an essential role in the signaling of numerous cytokines that have been implicated in the pathogenesis of inflammatory diseases. As a consequence, the JAKs have received significant attention in recent years from the pharmaceutical and biotechnology industries as therapeutic targets. Here, we provide a review of the JAK pathways, the structure, function, and activation of the JAK enzymes followed by a detailed look at the JAK inhibitors currently in the clinic or approved for these indications. Finally, a perspective is provided on what the past decade of research with JAK inhibitors for inflammatory indications has taught along with thoughts on what the future may hold in terms of addressing the opportunities and challenges that remain.

Studies of Jak/STAT3 expression and signalling in psoriasis identifies STAT3-Ser727 phosphorylation as a modulator of transcriptional activity

Jak/Tyk proteins have recently aroused as possible therapeutic targets for the treatment of psoriasis. In psoriasis, these proteins signal through STAT molecules including STAT3, and STAT3 expression and activation has been shown augmented in psoriatic lesions. Here, we characterized the expression of Jak/Tyk proteins in lesional compared with non-lesional psoriatic skin. Jak1, Jak2 mRNA and protein and Tyk2 mRNA appeared to be downregulated, whereas Jak3 mRNA expression was increased. Moreover, STAT3 expression and activation was examined in psoriasis. STAT3 is activated at two phosphorylation sites: Tyr705 and Ser727. Both phosphorylation sites were phosphorylated in lesional psoriatic skin. The activation of STAT3 by Jak/Tyk proteins was studied in cultured normal human keratinocytes. Tyr705 phosphorylation was induced by IL-6 and IL-20 in a Jak2-dependent manner, and moreover, phosphorylation of Tyr705 produced a strong increase in STAT3 transcriptional activity. TNFα, 12-O-Tetradecanoylphorbol 13-acetate (TPA) and UVB irradiation induced Ser727 phosphorylation of STAT3 in an ERK1/2- and p38 MAPK-dependent manner, which resulted in a modulatory effect on STAT3 transcriptional activity. Our results demonstrate how different signalling pathways can integrate and lead to regulation of STAT3 transcriptional activity.

Burden of disease: psoriasis and psoriatic arthritis

Psoriatic arthritis (PsA) increases the disease burden associated with psoriasis by further diminishing quality of life, increasing health care costs and cardiovascular risk, and potentially causing progressive joint damage. The presence of PsA influences psoriasis treatment by increasing overall disease complexity and, within the framework of current guidelines and recommendations, requiring the use of conventional disease-modifying anti-rheumatic drugs or tumor necrosis factor-α inhibitors in order to prevent progressive joint damage. Despite its important impact, PsA is still under-diagnosed in dermatology practice. Dermatologists are well positioned to recognize and treat PsA, given that it characteristically presents, on average, 10 years subsequent to the appearance of skin symptoms. Regular screening of psoriasis patients for early evident joint symptoms should be incorporated into daily dermatologic practice. Although drugs effective in PsA are available, not all patients may respond to treatment, and others may lose their initial response over time. New investigational therapies, such as inhibitors of interleukin-17A, interleukin-12/23, Janus kinase 3, or phosphodiesterase-4, may address unmet needs in psoriatic disease, with further research needed to determine the role of these agents in reducing joint damage and other comorbidities.

The role of JAK-3 in regulating TLR-mediated inflammatory cytokine production in innate immune cells

The role of JAK-3 in TLR-mediated innate immune responses is poorly understood, although the suppressive function of JAK3 inhibition in adaptive immune response has been well studied. In this study, we found that JAK3 inhibition enhanced TLR-mediated immune responses by differentially regulating pro- and anti- inflammatory cytokine production in innate immune cells. Specifically, JAK3 inhibition by pharmacological inhibitors or specific small interfering RNA or JAK3 gene knockout resulted in an increase in TLR-mediated production of proinflammatory cytokines while concurrently decreasing the production of IL-10. Inhibition of JAK3 suppressed phosphorylation of PI3K downstream effectors including Akt, mammalian target of rapamycin complex 1, glycogen synthase kinase 3β (GSK3β), and CREB. Constitutive activation of Akt or inhibition of GSK3β abrogated the capability of JAK3 inhibition to enhance proinflammatory cytokines and suppress IL-10 production. In contrast, inhibition of PI3K enhanced this regulatory ability of JAK3 in LPS-stimulated monocytes. At the transcriptional level, JAK3 knockout lead to the increased phosphorylation of STATs that could be attenuated by neutralization of de novo inflammatory cytokines. JAK3 inhibition exhibited a GSK3 activity-dependent ability to enhance phosphorylation levels and DNA binding of NF-κB p65. Moreover, JAK3 inhibition correlated with an increased CD4(+) T cell response. Additionally, higher neutrophil infiltration, IL-17 expression, and intestinal epithelium erosion were observed in JAK3 knockout mice. These findings demonstrate the negative regulatory function of JAK3 and elucidate the signaling pathway by which JAK3 differentially regulates TLR-mediated inflammatory cytokine production in innate immune cells.

Inhibition of Janus activated kinase-3 protects against myocardial ischemia and reperfusion injury in mice

Recent studies have documented that Janus-activated kinase (JAK)–signal transducer and activator of transcription (STAT) pathway can modulate the apoptotic program in a myocardial ischemia/reperfusion (I/R) model. To date, however, limited studies have examined the role of JAK3 on myocardial I/R injury. Here, we investigated the potential effects of pharmacological JAK3 inhibition with JANEX-1 in a myocardial I/R model. Mice were subjected to 45 min of ischemia followed by varying periods of reperfusion. JANEX-1 was injected 1 h before ischemia by intraperitoneal injection. Treatment with JANEX-1 significantly decreased plasma creatine kinase and lactate dehydrogenase activities, reduced infarct size, reversed I/R-induced functional deterioration of the myocardium and reduced myocardial apoptosis. Histological analysis revealed an increase in neutrophil and macrophage infiltration within the infarcted area, which was markedly reduced by JANEX-1 treatment. In parallel, in in vitro studies where neutrophils and macrophages were treated with JANEX-1 or isolated from JAK3 knockout mice, there was an impairment in the migration potential toward interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1), respectively. Of note, however, JANEX-1 did not affect the expression of IL-8 and MCP-1 in the myocardium. The pharmacological inhibition of JAK3 might represent an effective approach to reduce inflammation-mediated apoptotic damage initiated by myocardial I/R injury.

NF-κB and STAT3 inhibition as a therapeutic strategy in psoriasis: in vitro and in vivo effects of BTH

Benzo[b]thiophen-2-yl-3-bromo-5-hydroxy-5H-furan-2-one (BTH) is a simple and interesting synthetic derivative of petrosaspongiolide M, a natural compound isolated from a sea sponge with demonstrated potent anti-inflammatory activity through inhibition of the NF-κB signaling pathway. In the present study, we report the in vitro and in vivo pharmacological effect of BTH on some parameters related to the innate and adaptive response in the pathogenesis of psoriasis. BTH inhibited the release of some of the key psoriatic cytokines such as tumor necrosis factor α, IL-8, IL-6, and CCL27 through the downregulation of NF-κB in normal human keratinocytes. Moreover, it impaired signal transducers and activators of transcription 3 (STAT3) phosphorylation and translocation to the nucleus, which resulted in decreased keratinocyte proliferation. These results were confirmed in vivo in two murine models of psoriasis: the epidermal hyperplasia induced by 12-O-tetradecanoylphorbol-13-acetate and the imiquimod-induced skin inflammation model. In both cases, topical administration of BTH prevented skin infiltration and hyperplasia through suppression of NF-κB and STAT3 phosphorylation. Our results confirm the pivotal role of both transcriptional factors in skin inflammation, as occurs in psoriasis, and highlight the potential of small molecules as therapeutic agents for the treatment of this skin disease, with BTH being a potential candidate for future drug research.

Tofacitinib and other kinase inhibitors in the treatment of psoriasis

Protein kinases play a crucial role in the intracellular signaling pathways involved in inflammation and cell proliferation. Advances in our understanding of these metabolic pathways and of the role played by intracellular signaling in the pathogenesis of psoriasis have led to research in this area and the development of a new class of drugs for the treatment of psoriasis and other inflammatory processes. Since kinase inhibitors are small molecules, oral and topical treatments are possible. The future role of these molecules in the therapeutic arsenal used to treat psoriasis is as yet unknown because in most cases they are still in the early stages of research. The fact that these drugs may cost much less than biologic therapies could favor their approval in coming years. Tofacitinib, a Janus kinase inhibitor, is the drug that has reached the most advanced stage of research and has shown the most promising results.

Efficacy and safety of tofacitinib, an oral Janus kinase inhibitor, in the treatment of psoriasis: a Phase 2b randomized placebo-controlled dose-ranging study

BACKGROUND

Tofacitinib is a novel, oral Janus kinase inhibitor under investigation as a potential treatment for plaque psoriasis.

OBJECTIVES

This Phase 2b, 12-week, dose-ranging study (A3921047, NCT00678210) aimed to characterize the exposure-response, efficacy and safety of tofacitinib vs. placebo in patients with moderate-to-severe chronic plaque psoriasis.

METHODS

One hundred and ninety-seven patients were randomized. The primary endpoint was the proportion of patients achieving a ≥ 75% reduction in the Psoriasis Area and Severity Index (PASI 75) score at week 12.

RESULTS

At week 12, PASI 75 response rates were significantly higher for all tofacitinib twice-daily groups: 25·0% (2 mg; P < 0·001), 40·8% (5 mg; P < 0·0001) and 66·7% (15 mg; P < 0·0001), compared with placebo (2·0%). Significant increases in the proportion of PASI 75 responses were seen by week 4 and were maintained at week 12. Exposure-response over the 0-15 mg tofacitinib twice-daily dose range was successfully characterized. PASI 50, PASI 90 and Physician's Global Assessment response rates were also higher for tofacitinib vs. placebo. The most frequently reported adverse events (AEs) were infections and infestations: 22·4% (2 mg twice daily), 20·4% (5 mg twice daily), 36·7% (15 mg twice daily) and 32·0% (placebo). Discontinuations due to AEs were 6·0%, 2·0%, 4·1% and 6·1% of patients in the placebo, and 2, 5 and 15 mg twice-daily tofacitinib groups, respectively. Dose-dependent increases from baseline in mean serum high-density lipoprotein, low-density lipoprotein and total cholesterol, and decreases in haemoglobin and neutrophils were observed.

CONCLUSION

Short-term treatment with oral tofacitinib results in significant clinical improvement in patients with moderate-to-severe plaque psoriasis and is generally well tolerated.

Benzoxathiol derivative BOT-4-one suppresses L540 lymphoma cell survival and proliferation via inhibition of JAK3/STAT3 signaling

Persistently activated JAK/STAT3 signaling pathway plays a pivotal role in various human cancers including major carcinomas and hematologic tumors, and is implicated in cancer cell survival and proliferation. Therefore, inhibition of JAK/STAT3 signaling may be a clinical application in cancer therapy. Here, we report that 2-cyclohexylimino-6-methyl-6,7-dihydro-5H-benzo [1,3]oxathiol-4-one (BOT-4-one), a small molecule inhibitor of JAK/STAT3 signaling, induces apoptosis through inhibition of STAT3 activation. BOT-4-one suppressed cytokine (upd)-induced tyrosine phosphorylation and transcriptional activity of STAT92E, the sole Drosophila STAT homolog. Consequently, BOT-4-one significantly inhibited STAT3 tyrosine phosphorylation and expression of STAT3 downstream target gene SOCS3 in various human cancer cell lines, and its effect was more potent in JAK3-activated Hodgkin's lymphoma cell line than in JAK2-activated breast cancer and prostate cancer cell lines. In addition, BOT-4-one-treated Hodgkin's lymphoma cells showed decreased cell survival and proliferation by inducing apoptosis through down-regulation of STAT3 downstream target anti-apoptotic gene expression. These results suggest that BOT-4-one is a novel small molecule inhibitor of JAK3/STAT3 signaling and may have therapeutic potential in the treatment of human cancers harboring aberrant JAK3/STAT3 signaling, specifically Hodgkin's lymphoma.

Psoriasis: what we have learned from mouse models

Psoriasis is a common inflammatory skin disease of unknown etiology, for which there is no cure. This heterogeneous, cutaneous, inflammatory disorder is clinically characterized by prominent epidermal hyperplasia and a distinct inflammatory infiltrate. Crosstalk between immunocytes and keratinocytes, which results in the production of cytokines, chemokines and growth factors, is thought to mediate the disease. Given that psoriasis is only observed in humans, numerous genetic approaches to model the disease in mice have been undertaken. In this Review, we describe and critically assess the mouse models and transplantation experiments that have contributed to the discovery of novel disease-relevant pathways in psoriasis. Research performed using improved mouse models, combined with studies employing human cells, xenografts and patient material, will be key to our understanding of why such distinctive patterns of inflammation develop in patients with psoriasis. Indeed, a combination of genetic and immunological investigations will be necessary to develop both improved drugs for the treatment of psoriasis and novel curative strategies.