GDC-4379

GDC-4379 (also known as RG6244) is an investigational, inhaled small molecule inhibitor of Janus Kinase 1 (JAK1) developed by Genentech for the treatment of asthma. It is designed for delivery via a dry powder inhaler to provide localized anti-inflammatory effects in the lungs while minimizing systemic exposure. By selectively inhibiting JAK1, GDC-4379 blocks the signaling of key type-2 cytokines, including IL-4, IL-5, IL-13, and TSLP, which are central to the pathophysiology of airway inflammation. In a Phase 1 clinical trial (ACTRN12619000227190), the compound demonstrated dose-dependent reductions in fractional exhaled nitric oxide (FeNO), a clinical biomarker of airway inflammation, and was generally well-tolerated. Development of GDC-4379 has been discontinued, as it is no longer listed in Genentech's active pipeline.