VX-680/MK-0457 is a small-molecule Aurora kinase inhibitor with inhibition constants (K(i)) of 0.6, 18 and 4.6 nM for Aurora kinase A, B and C, respectively; it also inhibits Flt-3 and AN kinases, particularly mutant forms. The compound displays potent antitumor activity in a broad range of cancer cell lines and is well tolerated in preclinical studies. A phase I clinical trial of VX-680/MK-0457 was carried out in patients with chronic myeloid leukemia (CML) or acute lymphocytic leukemia (ALL) with the T315l Bcr-Abl resistance mutation and patients with refractory JAK2-positive myeloproliferative disease. VX-680/MK-0457 demonstrated encouraging antitumor activity and a good overall safety profile.