Three Aurora kinases, A-C, are involved in phosphorylation events that are critical for the completion of mitosis. Their expression is elevated in a variety of human cancers. AMG 900 is an orally bioavailable, selective Aurora kinase inhibitor with IC50 values of 5, 4, and 1 nM for Aurora A, B, and C, respectively. It is greater than 10-fold selective for Aurora kinases over p38α, TYK2, JNK2, Met, and Tie2 (IC50s = 53, 220, 520, 550, and 650 nM, respectively). At 2-3 nM, AMG 900 has been shown to inhibit the proliferation of 26 different tumor cell lines in vitro, including cell lines resistant to either the antimitotic agent paclitaxel or to other Aurora kinase inhibitors. Furthermore, AMG 900 is reported to be broadly active in multiple xenograft models, including three multidrug-resistant xenograft models, representing five tumor types.
