The suitability of treating atopic dermatitis with Janus kinase inhibitors

Modelling atopic dermatitis in healthy human skin for the characterization of topical compounds

Suitable human models for the development and characterization of topical compounds for inflammatory skin diseases such as atopic dermatitis are not readily available to date. We describe here the development of a translational model involving healthy human skin mimicking major aspects of AD and its application for the characterization of topical Janus kinase inhibitors. Full thickness human abdominal skin obtained from plastic surgery stimulated in vitro with IL4 and IL13 shows molecular features of AD. This is evidenced by STAT6 phosphorylation assessed by immunohistochemistry and analysis of skin lysates. Broad transcriptome changes assessed by AmpliSeq followed by gene set variation analysis showed a consistent upregulation of gene signatures characterizing AD in this model. Topical application of experimental formulations of compounds targeting the JAK pathway to full thickness skin normalizes the molecular features of AD induced by IL4 and IL13 stimulation. The inhibitory effects of topical JAK inhibitors on molecular features of AD are supported by pharmacokinetic analysis. The model described here is suited for the characterization of topical compounds for AD and has the potential to be extended to other inflammatory skin diseases and pathophysiological pathways.

Short-term efficacy and safety of biologics and Janus kinase inhibitors for patients with atopic dermatitis: A systematic review and meta-analysis

Background

In recent years, biologics targeting key cytokines and Janus kinase (JAK) inhibitors have demonstrated favorable efficacy and safety outcomes for atopic dermatitis (AD) therapy. To evaluate the short-term efficacy and safety of AD therapy involving biologics, JAK inhibitors, and their combination with topical corticosteroids (TCS) for patients with AD, we conducted this systematic review and meta-analysis. Using eligible randomized clinical trials (RCTs) of 12 or 16 weeks of treatment with systemic medications and 4 weeks of topical treatment for AD.

Methods

PubMed, Web of Science, ScienceDirect, and the Cochrane Library were searched from inception up to October 25, 2023. English-language randomized clinical trials (RCTs) of 12 or 16 weeks of treatment with systemic medications and 4 weeks of topical treatment for AD were included. Titles, abstracts, and articles were screened in duplicate. Of 7261 citations, 37 studies were included. The data were analyzed using Review Manager 5.4 and the outcomes were measured by the Eczema Area and Severity Index (EASI), Investigator Global Assessment (IGA), the pruritus Numerical Rating Scale (NRS), as well as instances of adverse events (AE), and serious AE (SAE), which were presented as risk ratio (RR) with a 95 % confidence interval (CI). The efficacy of the biological therapies was analyzed with the percentage of patients who have achieved EASI 75, EASI 90, IGA 0/1 and pruritus NRS4, while the safety of treatments was evaluated in terms of the number of patients who had ≥1 AE and who had at least one SAE.

Results

A total of 37 studies with 43 cohorts that examined 9 medications and placebo and involved 18172 participants were included. Compared with the placebo, all biologics and JAK inhibitors were associated with a higher response rate in efficacy outcomes, while systematic administration was presented by dupilumab 200 mg subcutaneously every 2 weeks with superior improvement in EASI 90 (RR 9.50, 95 % CI 2.31-39.03) and IGA0/1 (RR 17.00, 95 % CI 2.33-123.78), upadacitinib 30 mg once daily in EASI 75 (RR 5.14, 95 % CI 4.20-6.31) and Pruritus NRS4 (RR 5.73, 95 % CI 4.44-7.39), and external use was presented by ruxolitinib 1.5 % twice daily orally in EASI 75 (RR 4.14, 95 % CI 3.06-5.61) and Pruritus NRS4 (RR 4.08, 95 % CI 2.86-5.81), and most of doses led to a better safety profile. Most doses of baricitinib, dupilumab, tralokinumab, and upadacitinib in combination with TCS demonstrated good efficacy as compared with the control groups (placebo + TCS). However, patients receiving baricitinib at a dosage of 2 mg daily (RR 1.23, 95 % CI 1.02-1.49) and 4 mg daily (RR 1.39, 95 % CI 1.22-1.58) in combination with TCS, exhibited a higher incidence of one or more SAE as compared with those taking placebo + TCS.

Conclusion

Our research has revealed that ruxolitinib and dupilumab are effective and safe treatments for mild to moderate AD and moderate to severe AD, respectively. Additionally, the combination of dupilumab and TCS demonstrates greater efficacy and safety compared to baricitinib, tralokinumab, and upadacitinib with TCS as a background treatment for moderate to severe AD. We suggest that the use of topical JAK inhibitors could be a potential alternative to TCS when used in combination with systemic medications, as a novel approach to treat AD. Insufficient different data sources caused by partial interventions were only mentioned in a few articles and low event rates in safety analyses may lead to the results being biased. Further studies directly comparing existing and novel treatments are needed and will be included in forthcoming updates of this review. Our findings could form a useful foundation for developing a new generation of treatment guidelines for AD.

Real-Life Effectiveness and Safety of Upadacitinib in Adults and Adolescents with Moderate-to-Severe Atopic Dermatitis: A Single-Center 16-Week Study

INTRODUCTION

The treatment of severe atopic dermatitis (AD) includes cyclosporine and recently approved biologics and small molecules. Among these, upadacitinib is a selective inhibitor of Janus kinase 1, approved for the treatment of severe AD in adolescents/adults. Upadacitinib has shown efficacy and safety in several phase 3 clinical trials, but data on real-life patients are still lacking.

METHODS

We conducted a retrospective real-life observational study to evaluate the effectiveness and safety of upadacitinib up to week 16 in a cohort of both bio-naïve and bio-experienced patients. This study was carried out by analyzing the AD database records of an Italian referral hospital. Thirty-eight patients were included in this study, and 35 completed 16 weeks of treatment.

RESULTS

At week 16, out of 35 patients, the percentages of Eczema Area and Severity Index (EASI) 50, EASI 75, EASI 90 and EASI 100 responses were 94.29, 91.43, 74.29, and 60%, respectively. A decrease of at least 4 points from baseline of itch-NRS was reported by 94.74 and 91.43% of patients at weeks 8 and 16. Regarding the safety of upadacitinib, 26.32% of patients experienced at least one adverse event (AE), and a total of 13 AEs were recorded, including blood test abnormalities and papulopustular acne. None of our patients interrupted the drug because of an AE.

CONCLUSIONS

We observed higher rates of EASI75/EASI90/EASI100 responses at week 16, compared with data from clinical trials. The safety profile of upadacitinib was favorable, as no AEs leading to discontinuation were experienced by our patients up to week 16.

Molecular dissection of Janus kinases as drug targets for inflammatory diseases

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

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

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