KW-2449

KW-2449 is a multikinase inhibitor of FLT3, ABL, ABL-T315I and Aurora kinase that induces cytotoxicity in Molm14 cells (which harbor an FLT3/ITD mutation). In addition, KW-2449 potently inhibited ABL-T315I, which is associated with IM resistance, with an IC50 value of 4 nM. KW-2449 showed the potent growth inhibitory effects on leukemia cells with FLT3 mutations by inhibition of the FLT3 kinase, resulting in the down-regulation of phosphorylated-FLT3/STAT5, G(1) arrest, and apoptosis. Oral administration of KW-2449 showed dose-dependent and significant tumor growth inhibition in FLT3-mutated xenograft model with minimum bone marrow suppression. In FLT3 wild-type human leukemia, it induced the reduction of phosphorylated histone H3, G(2)/M arrest, and apoptosis. In imatinib-resistant leukemia, KW-2449 contributed to release of the resistance by the simultaneous down-regulation of BCR/ABL and Aurora kinases. KW-2449 has significant activity and warrants clinical study in leukemia patients with FLT3 mutations as well as imatinib-resistant mutations.