Definition

The dimesylate salt of cevidoplenib, an orally available inhibitor of spleen tyrosine kinase (SYK), with potential anti-inflammatory and immunomodulating activities. Upon oral administration, cevidoplenib binds to and inhibits the activity of SYK, blocking Fc receptor and B-cell receptor (BCR)-mediated signaling in inflammatory cells, including macrophages, neutrophils, mast cells, natural killer (NK) cells and B cells. This leads to the inhibition of the activation of these inflammatory cells, and the related inflammatory responses and tissue damage. SYK, a non-receptor cytoplasmic protein tyrosine kinase widely expressed in hematopoietic cells, plays a key role in Fc receptor and B-cell receptor signaling in inflammatory cells. It is involved in coupling activated immunoreceptors, such as Fc receptors and B-cell receptors, to signal downstream events that mediate diverse cellular responses, including proliferation, differentiation, and phagocytosis, which are important for allergic and antibody-mediated immune diseases such as immune thrombocytopenia (ITP).