Malignant JAK-signaling: at the interface of inflammation and malignant transformationPerner, Pahl, Zeiser
et alLeukemia (2025)
Abstract: The JAK pathway is central to mammalian cell communication, characterized by rapid responses, receptor versatility, and fine-tuned regulation. It involves Janus kinases (JAK1, JAK2, JAK3, TYK2), which are activated when natural ligands bind to receptors, leading to autophosphorylation and activation of STAT transcription factors [1, 2]. JAK-dependent signaling plays a pivotal role in coordinating cell communication networks across a broad spectrum of biological systems including development, immune responses, cell growth, and differentiation. JAKs are frequently mutated in the aging hematopoietic system [3, 4] and in hematopoietic cancers [5]. Thus, dysregulation of the pathway results in various diseases, including cancers and immune disorders. The binding of extracellular ligands to class I and II cytokine receptors initiates a critical signaling cascade through the activation of Janus kinases (JAKs). Upon ligand engagement, JAKs become activated and phosphorylate specific tyrosine residues on the receptor, creating docking sites for signal transducer and activator of transcription (STAT) proteins. Subsequent JAK-mediated phosphorylation of STATs enables their dimerization and nuclear translocation, where they function as transcription factors to modulate gene expression. Under physiological conditions, JAK-signaling is a tightly regulated mechanism that governs cellular responses to external cues, such as cytokines and growth factors, ensuring homeostasis and maintaining the functional integrity of tissues and organs. Highly defined regulation of JAK-signaling is essential for balancing cellular responses to inflammatory stimuli and growth signals, thus safeguarding tissue health. In contrast, dysregulated JAK-signaling results in chronic inflammation and unrestrained cellular proliferation associated with various diseases. Understanding the qualitative and quantitative differences at the interface of physiologic JAK-signaling and its aberrant activation in disease is crucial for the development of targeted therapies that precisely tune this pathway to target pathologic activation patterns while leaving homeostatic processes largely unaffected. Consequently, pharmaceutical research has targeted this pathway for drug development leading to the approval of several substances with different selectivity profiles towards individual JAKs. Yet, the precise impact of inhibitor selectivity and the complex interplay of different functional modules within normal and malignant cells remains incompletely understood. In this review, we summarize the current knowledge on JAK-signaling in health and disease and highlight recent advances and future directions in the field.© 2025. The Author(s).
Central TYK2 inhibition identifies TYK2 as a key neuroimmune modulatorMolitor, Hayashi, Lin
et alProc Natl Acad Sci U S A (2025) 122 (13), e2422172122
Abstract: GWAS have identified tyrosine kinase 2 (TYK2) variants in multiple inflammatory disorders, specifically a protective hypomorphic TYK2 allele (P1104A) in multiple sclerosis (MS). Impaired TYK2 signaling within the central nervous system (CNS) may impart the protective effects of TYK2 P1104A allele in MS. We deployed brain-penetrant TYK2 inhibitors (cTYK2i) alongside the peripherally restricted TYK2 inhibitor (pTYK2i; BMS-986165) to untangle the contributions of central TYK2 inhibition in diverse models of neuroinflammation. While pTYK2i had little impact, cTYK2i reduced clinical score, lymphoid cell infiltration, and cytokines/chemokines in experimental autoimmune encephalomyelitis (EAE). Microglial activation was attenuated in cTYK2i-treated EAE spinal cords and circulating neurofilament light (NfL) was reduced in plasma and cerebral spinal fluid (CSF). Additionally, cTYK2i was protective in an antibody-mediated mouse model of primary progressive MS (PPMS). Finally, we demonstrate TYK2 inhibition has a robust impact on a unique subset of activated astrocytes termed Interferon-Responsive-Reactive-Astrocytes (IRRA). The data presented herein identify a key role for CNS TYK2 signaling in regulating neuroinflammation and solidify TYK2 as a potential therapeutic target for MS.
Discovery of a Highly Potent and Selective Tyrosine Kinase 2 (TYK2) Degrader with In Vivo Therapeutic Efficacy in a Murine Psoriasis ModelXiong, Yang, Yang
et alJ Med Chem (2025)
Abstract: Tyrosine kinase 2 (TYK2), a critical scaffolding kinase required for type I interferon, IL-12 and IL-23 cytokine signaling, represents a compelling therapeutic target for various autoimmune diseases. However, existing TYK2 inhibitors only modulate its kinase activity. Here, we report the development of a first series of CRBN-recruiting TYK2 PROTACs based on an allosteric TYK2 inhibitor. Optimization of the potency and metabolic stability identified 15t as an exceptionally potent and selective TYK2 degrader with a DC50 value of 0.42 nM and a Dmax value of 95%, which potently and selectively blocked TYK2-dependent signaling. Importantly, 15t was active in vivo and significantly suppressed TYK2-mediated pathology in a murine psoriasis model without apparent toxicity. Collectively, our study provides a potentially valuable chemical knockdown probe for subtype-selective TYK2 degradation and further understanding TYK2 scaffolding biology, demonstrating the therapeutic potential of TYK2 PROTACs in immuno-inflammatory diseases such as psoriasis.
Deucravacitinib: Laboratory Parameters Across Phase 3 Plaque Psoriasis TrialsArmstrong, Kircik, Stein Gold
et alDermatol Ther (Heidelb) (2025)
Abstract: Deucravacitinib, an oral, selective, allosteric tyrosine kinase 2 inhibitor, is approved in the USA and other countries for treatment of adults with moderate to severe plaque psoriasis who are candidates for systemic therapy. In POETYK PSO-1 and PSO-2, deucravacitinib was superior to placebo and apremilast and well tolerated in patients with plaque psoriasis. Patients who completed PSO-1/PSO-2 could enroll in the POETYK long-term extension (LTE) trial. This analysis evaluates the effects of deucravacitinib on laboratory parameters.POETYK PSO-1 and PSO-2 were 52-week, phase 3, double-blinded trials that randomized patients 1:2:1 to placebo, deucravacitinib 6 mg once daily, or apremilast 30 mg twice daily. At week 52, eligible patients enrolled in POETYK LTE and received open-label deucravacitinib. Mean changes from baseline in laboratory parameters, laboratory adverse events (AEs), and laboratory AEs resulting in discontinuation were evaluated over 3 years.A total of 1519 patients received one or more doses of deucravacitinib across trials. Total exposure over 3 years was 3294.3 person-years. No clinically relevant mean changes were observed in laboratory parameters. Grade ≥ 3 laboratory AEs were infrequent during the 1-year period, with incidence rates remaining stable in patients treated with deucravacitinib through 3 years. Most laboratory AEs remained at the same grade; shifts to higher grades were infrequent, with most increases being to grade ≤ 2. Discontinuations due to laboratory AEs were rare.Deucravacitinib did not result in clinically meaningful changes in laboratory parameters over 3 years, including changes seen with Janus kinase (JAK) 1,2,3 inhibitors. Grade ≥ 3 laboratory AEs and discontinuations were rare.ClinicalTrials.gov identifier, POETYK PSO-1 (NCT03624127), POETYK PSO-2 (NCT03611751), POETYK LTE (NCT04036435).© 2025. The Author(s).
膜杰作
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