Olmutinib, also known as HM61713 and BI-1482694, is a potent small molecule inhibitor of Bruton's tyrosine kinase (BTK). BTK is a member of the Tec family of non-receptor protein tyrosine kinases. BTK is mostly expressed in hematopoietic cells such as B cells, mast cells and macrophages. BTK plays key roles in multiple cell signaling pathways including B-Cell Receptor (BCR) and Fc receptor (FcR) signaling cascades and is an essential mediator not only in B-cell dependent but also in myeloid cell dependent inflammatory arthritis. HM71224 has been selected as a novel therapeutic agent for the treatment of autoimmune diseases such as RA.