Expert: Inhibits Janus kinase (JAK) 1 and JAK2 signaling pathways. In myelofibrosis, constitutive activation of JAK-STAT signaling (often via JAK2 V617F, CALR, or MPL mutations) drives myeloproliferation, splenomegaly, and constitutional symptoms. JAK inhibition normalizes cytokine signaling and reduces malignant clone proliferation.

Everyday: JAK enzymes are like switches that tell bone marrow cells to grow uncontrollably. In myelofibrosis, these switches are stuck "on" (often due to a JAK2 mutation). JAK inhibitors flip these switches off, shrinking the enlarged spleen and reducing symptoms like fatigue, night sweats, and bone pain.

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JAK1/JAK2/ACVR1 inhibitor for MF with anemia. Unique triple inhibition: JAK1/2 for disease + ACVR1 (activin receptor) for anemia improvement. Differentiated from Jakafi/Vonjo by addressing anemia (hepcidin reduction). MOMENTUM Phase 3 pivotal. GSK markets.