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Results for “Janus Kinase 1”

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PubMed2026

A distinct psoriasis-atopic dermatitis overlapping phenotype in adults with dual type 2 and type 3 immune features and favorable response to Janus kinase 1 inhibition.

BACKGROUND: Patients exhibiting overlapping histopathologic features of psoriasis (Pso) and atopic dermatitis (AD) present a diagnostic and therapeutic challenge. OBJECTIVES: To delineate the clinicopathological and immunologic portrait of psoriasis-atopic dermatitis overlapping (Pso-Ec) for integrated diagnosis and therapeutic decision-making. METHODS: We conducted a 2-center prospective study comparing 30 Pso-Ec patients with typical Pso and AD cohorts. Clinicopathological characteristics and immunologic profiling of lesional skin and peripheral blood were analyzed, and treatment courses were assessed. RESULTS: Pso-Ec patients (aged 13-72 years; mean age: 49.7 years) presented with ill-defined erythematous plaques with thin scales, excoriation, intense itching, and mixed psoriatic-eczematous histology. Immune profiling showed co-existence of helper T cell 2/cytotoxic T cell 2 and helper T cell 17/cytotoxic T cell 17 in skin and blood, with Janus kinase (JAK) 1 signal transducer and activator of transcription 2/6 signaling involvement. Responses to prior Pso-targeted (n = 18) and AD-targeted (n = 15) biologics were often inadequate. In contrast, JAK1 inhibitors achieved minimal disease activity (body surface area ≤ 2, numerical rating scale ≤1) during a median follow-up of 17 months. No progression to classic Pso or AD phenotypes was observed. LIMITATIONS: Sample size was limited and immunologic analyses were performed in a representative subset of patients. CONCLUSIONS: Pso-Ec represents a distinct, predominantly adult-onset phenotype driven by dual type 2 and type 3 inflammation, and JAK1 inhibitors appear as an effective option.

Humans↗

PubMed1992

JAK2, a third member of the JAK family of protein tyrosine kinases.

We have isolated cDNA clones encoding a third, widely expressed, member of the JAK family of protein tyrosine kinases (PTKs). The anticipated amino acid sequence of JAK2 predicts the presence of two kinase-related domains, a feature characteristic of this family of PTKs. The structural similarity of JAK2 to the other members of this family extends towards their N-termini, beyond the two kinase-related domains, and reveals five further domains of substantial amino acid similarity. The C-terminal portion of one of these domains, the JH4 domain, bears an intriguing, albeit tenuous, similarity to the core element of the SH2 domain, whereas the remaining JAK homology domains do not appear to be a feature of other known proteins.

Amino Acid Sequence↗

PubMed2026

Efficacy, Safety, and Pharmacokinetics of Upadacitinib Among Patients in East Asia With Moderately to Severely Active Ulcerative Colitis: A Post Hoc Subanalysis of Randomized Phase 3 Studies.

BACKGROUND AND AIM: Upadacitinib, a selective Janus kinase 1 inhibitor, is approved to treat moderately to severely active ulcerative colitis (UC). This post hoc subanalysis evaluated the efficacy, safety, and pharmacokinetics of upadacitinib in patients in East Asia. METHODS: U-ACHIEVE (UC1; NCT02819635) and U-ACCOMPLISH (UC2; NCT03653026) were Phase 3, multicenter, randomized, double-blind, induction studies evaluating upadacitinib 45 mg or placebo daily in adults with moderately to severely active UC. Clinical responders to 8 weeks of upadacitinib induction were eligible to receive upadacitinib 15 mg, upadacitinib 30 mg, or placebo daily in the 52-week U-ACHIEVE maintenance study (UC3; NCT02819635). Efficacy outcomes, safety, and pharmacokinetics were evaluated among East Asian patients. RESULTS: A higher proportion of East Asian patients achieved clinical remission with upadacitinib than placebo at induction Week 8 (UC1: n = 127, 31.4% vs. 7.3%; UC2: n = 114, 31.2% vs. 2.7%) and maintenance Week 52 (UC3: n = 184, upadacitinib 15 mg, 52.4%; upadacitinib 30 mg, 53.8%; placebo, 10.7%). Rates of endoscopic outcomes were higher with upadacitinib than with placebo across studies. No new safety signals were identified. Herpes zoster occurrences were low (UC1 and UC2: upadacitinib 45 mg, two events [in one patient]; placebo, zero events; UC3: upadacitinib 15 mg, five events; upadacitinib 30 mg, eight events; placebo, zero events). Pharmacokinetics and trends in the relationship between upadacitinib exposure and efficacy were consistent in the East Asian and global populations. CONCLUSION: Upadacitinib was generally well tolerated and effective for treating moderately to severely active UC in patients in East Asia, with a favorable benefit-risk profile consistent with the global population. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02819635, NCT03653026.

Humans↗

PubMed2026

Genome-wide CRISPR screen identifies a cytokine-enhancer circuit driving HIF-2α activation in renal cancer.

Resistance to HIF-2α inhibitors such as belzutifan underscores the need to better understand how HIF-2α is transcriptionally regulated in clear cell renal cell carcinoma (ccRCC). Here, we uncover a cytokine-driven enhancer mechanism that sustains HIF-2α expression through the JAK1/STAT3 signaling pathway. Using a genome-wide CRISPR screen in von Hippel-Lindau-deficient (VHL-deficient) ccRCC cells, we identified SOCS3 as a key negative regulator of HIF-2α. Mechanistically, loss of SOCS3 activates JAK1/STAT3 signaling, leading to the recruitment of STAT3 to distal enhancers upstream of endothelial PAS domain-containing protein (EPAS1) that physically loop to its promoter to drive HIF-2α transcription. This cytokine-enhancer circuit was recapitulated in samples from patients with ccRCC and functionally validated using CRISPR interference (CRISPRi), which disrupted enhancer-promoter looping and reduced tumor growth in HIF-2α-dependent models. SOCS3 overexpression or pharmacologic inhibition of JAK1/STAT3 markedly suppressed HIF-2α expression and tumor progression both in vitro and in vivo. Unlike prior studies focusing on VHL/HIF occupancy-driven enhancer activation, this work defines a trans-acting cytokine-JAK1/STAT3 pathway that transcriptionally controls EPAS1. Together, these findings reveal a targetable enhancer mechanism that sustains HIF-2α expression and suggest that combined inhibition of JAK1/STAT3 and HIF-2α may overcome therapeutic resistance in kidney cancer.

Basic Helix-Loop-Helix Proteins↗

PubMed2025

miR-9-5p/HMMR regulates the tumorigenesis and progression of clear cell renal cell carcinoma through EMT and JAK1/STAT1 signaling pathway.

BACKGROUND: The most common malignant type of kidney cancer is clear cell renal cell carcinoma (ccRCC). The expression levels of hyaluronan-mediated motility receptor (HMMR) in many tumor types are significantly elevated. HMMR is closely associated with tumor-related progression, treatment resistance, and poor prognosis, and has yet to be fully investigated in terms of its expression patterns and molecular mechanisms of action in ccRCC. Further research is imperative to elucidate these aspects. METHODS: We used The Cancer Genome Atlas (TCGA) database to preliminarily investigate HMMR expression and function in ccRCC and the data for 19 samples from the NCBI GEO database (GSE207493) for single-cell analysis. We assessed the differential expression level of HMMR between ccRCC cancerous tissues and their matched non-tumor tissues. Subsequently, a series of in vivo and in vitro experiments were designed to elucidate the biological function of HMMR in ccRCC, including Transwell assays, CCK-8 assays, clone formation assays and subcutaneous xenograft experiments in nude mice. Through bioinformatics analysis, we identified potential microRNAs (miRNAs) that may regulate HMMR, as well as the possible signaling pathways involved. Finally, we conducted a series of cellular functional experiments to validate our hypotheses regarding the HMMR axis. RESULTS: HMMR expression was significantly up-regulated in tumor tissues of ccRCC patients, and elevated HMMR expression level showed a strong correlation with ccRCC progression and adverse prognoses of patients. Knocking down HMMR inhibited the proliferative and migratory abilities of ccRCC cells, while its overexpression amplified these oncogenic properties. In nude mice model, reduced HMMR expression inhibited ccRCC tumor proliferation in vivo. Furthermore, overexpression of an upstream transcriptional regulator, miR-9-5p, effectively downregulated HMMR expression and thus impeded ccRCC cells proliferation and migration. HMMR might influence ccRCC growth via the Epithelial-Mesenchymal Transition (EMT) pathway and the Janus Kinase 1/Signal Transducer and Activator of Transcription 1 (JAK1/STAT1) pathway. CONCLUSIONS: HMMR is overexpressed in ccRCC, and there is a significant link between high HMMR expression and tumor progression, as well as poor patient prognosis. Specifically, HMMR could be targeted and inhibited by miR-9-5p and might modulate the tumorigenesis and progression of ccRCC through both EMT and JAK1/STAT1 signaling pathway.

Carcinoma, Renal Cell↗

PubMed2026

Shared genetic architecture and therapeutic targets across paediatric immune-mediated diseases.

OBJECTIVES: Paediatric-onset immune-mediated inflammatory diseases (IMIDs), including juvenile idiopathic arthritis and related rheumatic diseases, remain genetically undercharacterised. We aimed to define shared and category-specific genetic architecture across paediatric IMIDs, compare signals with adult IMIDs, and identify therapeutic opportunities. METHODS: We analysed 24 paediatric IMIDs classified as autoimmune, polygenic-autoinflammatory, mixed-pattern, or allergic. Genome-wide association analyses included 18,086 cases and 131,019 controls of European ancestry. We estimated single nucleotide polymorphism (SNP)-based heritability, genetic correlations, and polygenic overlap; performed subset-based meta-analysis; and conducted functional annotation, gene prioritisation, pathway and protein network analyses, adult-IMID comparison, and drug-target prioritisation. RESULTS: SNP-based heritability ranged from 28.9% for allergic IMIDs to 61.9% for autoimmune IMIDs. Genetic correlation and polygenic modelling supported partial sharing across categories with category-specific components. Meta-analysis identified 39 genome-wide significant loci outside the Major Histocompatibility Complex (MHC) region, including 15 previously unreported loci; 19 loci were shared between categories. Gene-prioritisation and protein interaction analyses identified a core MHC-centred antigen-presentation network, with category-enriched modules involving complement, innate/barrier pathways, epithelial biology, and type 2 immunity. Enriched pathways included nuclear factor κB signalling, T helper 17 related pathways, Janus kinase-signal transducer and activator of transcription signalling, programmed cell death protein 1/programmed death‑ligand 1, cytotoxic T‑lymphocyte associated protein 4 regulation, and osteoclast differentiation, several of which are relevant to rheumatic diseases. Paediatric IMIDs shared broad polygenic architecture with adult IMIDs, whereas top-ranked genes converged strongly with adult rheumatic diseases. Priority Index analysis identified 178 high-scoring genes, including 43 approved or investigational IMID drug targets. CONCLUSIONS: Paediatric-onset IMIDs share core pathways with adult forms but exhibit distinct genetic architecture shaped by age-specific immune and neurodevelopmental biology. These findings provide a genomic framework for paediatric precision medicine, guiding classification, risk prediction, and therapeutic development.

Humans↗

PubMed2026

Age as a core disease modifier: Distinct clinical, molecular and prognostic landscapes of essential thrombocythaemia in adolescents and young adults.

Essential thrombocythaemia (ET) in adolescents and young adults (AYA, 15-39 years) is a distinct entity with an incompletely defined prognosis. In this multicentre retrospective study, 1728 ET patients from 29 centres across China were stratified into AYA (n = 328) and non-AYA (≥40 years, n = 1400) cohorts. We compared their clinical profiles, genomic landscapes, long-term outcomes and risk factors for progression to post-ET myelofibrosis (MF). AYA patients had fewer cardiovascular risks and lower thrombosis rates, but higher rates of extreme thrombocytosis. Molecularly, AYA patients were enriched for calreticulin (CALR) mutations, whereas Janus kinase 2 (JAK2) predominated in older patients. The burden of non-driver mutations (tet methylcytosine dioxygenase 2 [TET2], DNA methyltransferase 3A [DNMT3A], ASXL transcriptional regulator 1 [ASXL1], SH2‑B adaptor protein 3 [SH2B3]) was lower in AYA patients. Consequently, AYA patients achieved superior long-term outcomes across all key survival endpoints, including overall, myelofibrosis-free and leukaemia-free survival. Analysis of post-ET MF progression risks identified age-specific patterns: CALR mutations are enriched in younger patients and show an age-specific association with MF progression. AYA-ET constitutes a unique clinicomolecular subtype with a favourable prognosis, supporting age-stratified management. The enrichment of CALR mutations and their specific link to MF progression in young patients underscore the urgent need for targeted therapies against CALR-mutant clones.

adolescents and young adults (AYA)↗

PubMed2026

The emerging applications of JAK inhibitors in dermatology - a systematic review.

BACKGROUND: Janus kinase (JAK) inhibitors are established treatments for selected dermatologic conditions, but their off-label use has expanded across refractory skin diseases. METHODS: We systematically searched MEDLINE, Embase, and Web of Science from inception to October 1, 2025, for studies reporting off-label JAK inhibitor use in dermatologic disorders beyond approved or late-phase trial indications. RESULTS: Of 9,182 records screened, 277 studies met the inclusion criteria, comprising 210 case reports, 55 case series, and 12 retrospective studies involving 764 patients. Owing to substantial clinical heterogeneity, findings were narratively synthesized using a structured disease-family framework. Off-label use most commonly involved lichenoid, neutrophilic, and granulomatous dermatoses. Overall, 725/764 (94.88%) patients experienced clinical benefit, including complete or near-complete response in 209/764 (27.35%) and significant or partial improvement in 516/764 (67.53%). Thirty-five patients (4.58%) showed no clinical change, and four (0.52%) experienced disease worsening. A total of 154 adverse events were reported, most commonly with tofacitinib; most were mild to moderate, although six were serious and 25 resulted in treatment discontinuation. CONCLUSION: JAK inhibitors demonstrate promising therapeutic potential across a broad spectrum of refractory dermatological diseases. The predominance of uncontrolled case-based evidence, heterogeneous dosing, and frequent combination therapy limits attribution of efficacy and safety to JAK inhibitor monotherapy. Prospective controlled studies are needed to better define their therapeutic role.

Humans↗

PubMed2025

Comparative Safety of Janus Kinase Inhibitors vs Tumor Necrosis Factor Antagonists in Patients With Inflammatory Bowel Diseases.

BACKGROUND & AIMS: We conducted a retrospective cohort study comparing the safety of Janus kinase (JAK) inhibitors vs tumor necrosis factor-a (TNF) antagonists in patients with inflammatory bowel diseases (IBDs). METHODS: Using an administrative claims database, we identified patients with IBD who were new users of either JAK inhibitors or TNF antagonists between 2016 and 2023 and had insurance coverage for at least 1 year before and after treatment initiation. We compared the risk of infections (overall and serious infections requiring hospitalization), venous thromboembolism (VTE), and major adverse cardiovascular events (MACE) through stabilized inverse probability of treatment weighted Cox proportional hazards model accounting for disease characteristics, health care utilization, comorbidities, prior and concomitant medications, and competing risk of mortality. RESULTS: We included 856 patients treated with JAK inhibitors (age, 47 ± 17 years; 82% with ulcerative colitis [UC]) and 9422 patients treated with TNF antagonists (age, 45 ± 18 years; 44% with UC). JAK inhibitors were associated with higher risk of overall infections (incidence rate, 62.4 per 100 person-years [PY] vs 37.4 per 100 PY; hazard ratio [HR], 1.60; 95% confidence interval [CI], 1.33-1.93), but not serious infections (4.9 vs 5.4; HR, 0.97; 95% CI, 0.66-1.44) compared with TNF antagonists. There was no difference in the risk of VTE (1.3 vs 1.2; HR, 0.66; 95% CI, 0.28-1.57) and MACE (0.4 vs 0.7; HR, 0.50; 95% CI, 0.19-1.30). Findings were largely stable on subgroup analyses based on type of IBD, type of JAK inhibitors, age, prior biologic exposure, concomitant use of corticosteroids, and baseline risk of adverse events. CONCLUSIONS: In an observational study of patients with IBD, JAK inhibitors were not associated with an increased risk of serious infections, VTE, or MACE compared with TNF antagonists, although the overall risk of infections was higher.

Humans↗

PubMed2026

The tumor suppressor NDRG2 recruits protein phosphatase 2A to suppress STAT5 phosphorylation in adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T-cell malignancy with a poor prognosis that is caused by human T-cell leukemia virus type 1 infection. We previously demonstrated that N-myc downstream-regulated gene 2 (NDRG2) is significantly downregulated in ATL, resulting in aberrant activation of the signal transduction pathways through the dissociation of serine/threonine protein phosphatase 2A. To identify potential targets of NDRG2, we performed comprehensive mass spectrometry of differentially phosphorylated peptides in ATL cells with overexpression of NDRG2 using a TiO2-based enrichment method. Kyoto Encyclopedia of Genes and Genomes and gene ontology analysis revealed that the downregulated phosphopeptides correlated with signaling pathways, T-cell differentiation, and proliferation. Our results identified signal transducer and activator of transcription 5B as a novel NDRG2-regulated protein that is dephosphorylated at serine 193 and tyrosine 699. Although enforced expression of NDRG2 in ATL cell lines does not change the phosphorylation of Janus kinase 3, an upstream regulator of STAT5, phosphorylated STAT5 at tyrosine and serine is significantly suppressed by the direct binding to STAT5 with NDRG2 leading to the inhibition of STAT5 downstream gene expression. Furthermore, NDRG2 binds to STAT5B with alanine replacement of Y699 (Y699A), but only weakly associates with S193A, suggesting that NDRG2 is directly involved in serine phosphorylation through the recruitment of serine/threonine protein phosphatase 2A to STAT5. Because S193 A remarkably induces reduced phosphorylation of Y699 and subsequent transcriptional activity, the induction of serine phosphorylation through the loss of NDRG2 expression is dispensable for STAT5 tyrosine phosphorylation and activity. Since the loss of NDRG2 expression is essential factor to maintenance of ATL cells by STAT5 activity through phosphorylation of serine and tyrosine, targeting STAT5 becomes a feasible and effective strategy in NDRG2-deficient ATL.

Humans↗

PubMed2026

Clinical and genetic features of Ph-negative myeloproliferative neoplasms with dual-driver gene positivity.

OBJECTIVES: To investigate the clinical laboratory characteristics and gene mutation features of dual-driver gene positivity in patients with Philadelphia chromosome-negative myeloproliferative neoplasm (Ph-negative MPN). METHODS: We conducted a retrospective analysis of clinical data and genetic test results from 203 newly diagnosed patients with Ph-negative MPN. Of these, 194 had single-driver gene positivity and 9 had dual-driver gene positivity. High-throughput sequencing was used to detect mutations in JAK2, CALR, and MPL. Clinical characteristics and gene mutation profiles were compared between the two patient groups. RESULTS: The incidence of dual-driver gene positivity was 4.4% (9/203), with the most common combinations being JAK2 with CALR (4 patients) and JAK2 with MPL (4 patients). Compared with the single-driver group, the dual-driver group had a significantly higher risk of bleeding [4.1% (8/194) vs. 33.3% (3/9), P = 0.008] and a higher proportion of uncommon mutations [3.6% (7/194) vs. 33.3% (3/9), P = 0.006]. No statistically significant differences were observed between the two groups regarding age, thrombosis incidence, splenomegaly, or routine blood test indicators. During follow-up, 1 patient in the dual-driver group died from cerebrovascular disease. No leukaemia transformation or disease-related deaths occurred among the remaining patients. DISCUSSION: The increased bleeding risk in dual-driver patients may be related to a higher proportion of CALR mutations, elevated platelet counts, and higher variant allele frequencies, though these findings require validation in larger cohorts due to the small sample size. The higher prevalence of uncommon mutations suggests a more complex mutational landscape in this subgroup. CONCLUSION: Patients with Ph-negative MPN and dual-driver gene positivity may have a higher risk of bleeding and a more complex gene mutation profile.

Humans↗

PubMed2026

Efficacy and safety of Ruxolitinib-based combination therapy in the patients with Myelofibrosis (MF): a systematic review and meta-analysis.

BACKGROUND: Myelofibrosis (MF) is a chronic myeloproliferative neoplasm. Although Ruxolitinib, a JAK1/2 inhibitor, remains the cornerstone of MF treatment, it does not reverse disease progression, and resistance frequently emerges. These limitations have prompted investigation into combination therapies targeting pathways beyond the JAK-STAT axis. This meta-analysis aims to evaluate the efficacy and safety of Ruxolitinib-based combination therapies in patients with MF. METHODS: We conducted a systematic search of databases for studies published through August 1, 2025. Thirteen distinct Ruxolitinib-based combination regimens were included. Primary efficacy endpoints were ≥35% spleen volume reduction at 24 weeks (SVR35) and ≥50% reduction in total symptom score (TSS50). Safety endpoints focused on the incidence of grade 3/4 thrombocytopenia and anemia. Subgroup analyses were performed based on prior JAK inhibitor exposure and therapeutic mechanism of action. RESULTS: A total of 19 studies comprising 1,088 patients were included in the meta-analysis. Among JAK inhibitor-naïve patients, the combination of Ruxolitinib with Selinexor demonstrated the highest efficacy (SVR35: 92%; TSS50: 78%), followed by Ruxolitinib plus BMS-986158 (SVR35: 90%). For patients with prior JAK inhibitor exposure, Ruxolitinib plus Siremadlin (SVR35: 45%) showed notable activity. CONCLUSION: For JAK inhibitor-naïve patients, Ruxolitinib-based combination regimens demonstrated satisfactory clinical responses and the potential for meaningful disease control. For patients with prior JAK inhibitor exposure, the addition of combination therapy drugs may further enhance the efficacy. Personalized treatment selection remains essential, as therapeutic efficacy is significantly influenced by prior JAK inhibitor exposure.

Humans↗

PubMed2026

Efficacy and safety of JAK inhibitors in Behçet syndrome: systematic literature review.

OBJECTIVES: Given the active role of the JAK signaling pathway and the multifactorial immune mediators observed in Behçet syndrome (BS), JAK inhibitors (JAKi) may be promising agents. In this systematic literature review (SLR), we aim to evaluate the efficacy and safety of JAKi in BS. METHODS: A systematic literature search was conducted in Embase, PubMed, and the Cochrane Library to identify all reports on the efficacy and safety of JAKi in patients with BS. The SLR protocol was registered with the International Prospective Registry of Systematic Reviews (CRD420251000172). We additionally presented our patient with gastrointestinal involvement treated with upadacitinib. RESULTS: Among the 92 patients (48 men, mean (SD) age 38.5 (13.5) years), 46 used tofacitinib, 31 used baricitinib, and 15 used upadacitinib. All but 1 patient had used at least one previous conventional immunosuppressive, and 57.6% were refractory to at least one prior tumor necrosis factor inhibitor. JAKi were used in combination with conventional immunosuppressive and/or glucocorticoids in 90.6% of the patients. The primary indication for JAKi initiation was gastrointestinal involvement in 46 (50%) patients including our patient, vascular involvement in 22 (23.9%), uveitis in 19 (20.6%), and mucocutaneous and/or articular involvement in 5 (5.6%) patients. The remission rates for overall, gastrointestinal, vascular, and eye involvement were 85.9%, 82.6%, 90.9%, and 84.2%. Serious adverse events were observed in 5.4% of the patients. No thrombotic events were reported. CONCLUSION: This SLR showed that JAKi may be effective in refractory BS patients with a favorable safety profile.

Humans↗