VX-745 S1458

VX-745 selectively inhibits p38α and p38β MAPK with IC50 of 10 nM and 220 nM, respectively, but not p38γ MAPK and a large panel of other kinases, with IC50 larger than 20 µM. In a human peripheral blood mononuclear cell (PBMC) assay, VX-745 provides IC50 of 56 and 52 nM for IL-1β and TNFα, respectively. VX-745 blocks IL-6 and IL-8 production induced by IL-1 and TNFα, and COX-2 synthesis mediated by LPS and IL-1β. ^[1-3] VX-745 (60 nM-20 µM) inhibits IL-6 and VEGF secretion in bone marrow stromal cells (BMSCs), without affecting their viability. VX-745 also inhibits TNF-α-induced IL-6 secretion in BMSCs. VX-745 inhibits both multiple myeloma (MM) cell proliferation and IL-6 secretion in BMSCs triggered by adherence of MM cells to BMSCs, suggesting that VX-745 can inhibit paracrine multiple myeloma (MM) cell growth in the BM milieu and overcome cell adhesion-related drug resistance. ^[4]