PRT062607 is a novel, highly selective Syk inhibitor with IC50 of 1 nM, >80-fold selective for Syk than Fgr, Lyn, FAK, Pyk2 and Zap70.

PRT062607 anti-SYK activity is at least 80-fold greater than its affinity for other kinases. at least 80-fold greater than its affinity for other kinases. PRT062607 potently inhibits B cell antigen receptor-mediated B cell signaling and activation (IC50 0.27 and 0.28 μM, respectively) and Fcε receptor 1-mediated basophil degranulation (IC50 0.15 μM).PRT062607 inhibits BCR-dependent secretion of the chemokines CCL3 and CCL4 by CLL cells, and leukemia cell migration toward the tissue homing chemokines CXCL12, CXCL13, and beneath stromal cells. PRT062607 furthermore inhibits Syk and extracellular signal-regulated kinase phosphorylation after BCR triggering.