JAK1/2

Class

Topical JAK1/2 inhibitor

JAK1 and JAK2 are members of the Janus kinase family, enzymes that sit just inside the cell membrane attached to receptors for cytokines and growth factors. When a cytokine binds its receptor, JAK1 and JAK2 become activated and add phosphate groups to STAT proteins, which then travel to the nucleus and switch on genes involved in inflammation, cell proliferation, and immune signaling. Many inflammatory skin diseases, such as atopic dermatitis and vitiligo, are driven in part by cytokines that signal through this JAK1/2-STAT axis, including interferons and interleukins that recruit immune cells and disrupt the skin barrier. Inhibiting JAK1 and JAK2 together blocks this shared signaling node, dampening the output of several inflammatory cytokines at once rather than targeting just one. Formulating such an inhibitor as a topical treatment, applied directly to the skin, allows the drug to act locally at the site of disease while limiting how much reaches the bloodstream, which is intended to reduce the systemic immune suppression and blood-count effects associated with oral JAK inhibitors. This class is broadly relevant to chronic inflammatory and autoimmune skin conditions where cytokine-driven signaling maintains disease activity.