G-0853 (also GDC-0853, or Fenebrutinib) is a potent, selective, orally administered, and noncovalent Bruton's tyrosine kinase (Btk) inhibitor currently in clinical development. Upon administration, G-0853 inhibits the activity of Btk and prevents the activation of the B-cell antigen receptor (BCR) signaling pathway. This prevents both B-cell activation and Btk-mediated activation of downstream survival pathways, which leads to the inhibition of the growth of malignant B-cells that overexpress BTK. BTK is overexpressed in B-cell malignancies, and plays an important role in B-lymphocyte development, activation, signaling, proliferation and survival. G-0853 suppresses B cell- and myeloid cell-mediated components of disease and demonstrates dose-dependent activity in an in vivo rat model of inflammatory arthritis. G-0853 demonstrates highly favorable safety, pharmacokinetic (PK), and pharmacodynamic (PD) profiles in preclinical and Phase 2 studies ongoing in patients with rheumatoid arthritis, lupus, and chronic spontaneous urticaria.