gusacitinib

Gusacitinib is an investigational oral small molecule that acts as a dual inhibitor of Janus kinases (JAK) and spleen tyrosine kinase (SYK). It was originally developed by Asana BioSciences and has been studied primarily for the treatment of moderate to severe chronic hand eczema. Gusacitinib inhibits multiple inflammatory pathways by targeting both JAK family kinases (including TYK2) and SYK signaling. Clinical studies have shown rapid and significant improvement in disease severity scores in patients with chronic hand eczema. The drug has received FDA Fast Track designation for this indication due to its potential to address unmet medical needs in dermatology. In 2022, Formation Bio acquired gusacitinib from Asana BioSciences; subsequently, Libertas Bio (a subsidiary of Formation Bio) licensed it to Sanofi in 2025 for development in new indications[2][6][8].

Other names

1-(4-(4-(4-hydroxy-piperidin-1-yl)-phenylamino)-5-oxo-5,6-dihydro-pyrimido(4,5-d)pyridazin-2-yl)-piperidin-4-yl-acetonitrile