Janus kinase 3 and Tyrosine kinase 2 (JAK3/TYK2)

Janus kinase 3 (JAK3) and Tyrosine kinase 2 (TYK2) are members of the Janus kinase (JAK) family of non-receptor tyrosine kinases that play critical roles in the JAK-STAT signaling pathway [2, 10, 12]. JAK3 is primarily expressed in hematopoietic and lymphoid cells, where it associates with the common gamma chain (γc) of cytokine receptors to mediate signaling for interleukins such as IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21, which are essential for lymphocyte development and function [7, 13, 47]. TYK2 is more ubiquitously expressed and mediates signaling for Type I interferons, IL-12, and IL-23, which are key drivers of Th1 and Th17 immune responses [7, 11, 19, 32]. Dual targeting of JAK3 and TYK2 is an emerging therapeutic strategy aimed at simultaneously modulating lymphocyte activity and the IL-23/Th17 axis, which are central to the pathogenesis of various autoimmune and inflammatory diseases [47]. Drugs targeting this combination, such as OST-122 and TD-5202, are being investigated for conditions like ulcerative colitis and psoriasis to provide potent anti-inflammatory effects while potentially minimizing the off-target safety issues associated with broader JAK1 or JAK2 inhibition, such as anemia or severe immunosuppression [1, 21, 47]. Additionally, JAK3 and TYK2 have been identified as potential prognostic biomarkers in certain malignancies, such as stomach adenocarcinoma, where their elevated expression correlates with poor patient outcomes [20].

Other names

JAK3TYK2Janus kinase 3Tyrosine kinase 2JAK-3TYK-2JAK3/TYK2 dual target

Inhibition of the catalytic (JH1) or pseudokinase (JH2) domain of JAK3 and TYK2, blocking the JAK-STAT signaling pathway and preventing cytokine-mediated gene transcription.