KW-2449S2158

KW-2449, a multikinase inhibitor of FLT3, ABL, ABL-T315I, and Aurora kinase, is under investigation to treat leukemia patients. KW-2449 shows 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, G1 arrest, and apoptosis. Oral administration of KW-2449 shows dose-dependent and significant tumor growth inhibition in FLT3-mutated xenograft model with minimum bone marrow suppression. In FLT3 wild-type human leukemia, KW-2449 induces the reduction of phosphorylated histone H3, G2/M arrest, and apoptosis. In Imatinib-resistant leukemia, KW-2449 contributes to release of the resistance by the simultaneous down-regulation of BCR/ABL and Aurora kinases. The inhibitory activity of KW-2449 is not affected by the presence of human plasma protein, such as α1-acid glycoprotein. KW-2449 has potent growth inhibitory activity against various types of leukemia by several mechanisms of action. KW-2449 has significant activity and warrants clinical study in leukemia patients with FLT3 mutations as well as Imatinib-resistant mutations. Phosphorylation levels of FLT3 and STAT5 are decreased by KW-2449 in a dose-dependent manner. In addition, it potently inhibits ABL-T315I, which is associated with IM resistance, with IC50 of 4 nM. On the other hand, KW-2449 has little effect on PDGFRβ, IGF-1R, EGFR, and various serine/threonine kinases even at a concentration of 1 μM. KW-2449 has the potent growth inhibitory activities against not only FLT3/ITD-expressing leukemia cells but also FLT3/KDM-activated and wild-type FLT3-overexpressing leukemia cells. In accordance with growth inhibitory effect, KW-2449 suppresses the phosphorylations of FLT3 (P-FLT3) and its downstream molecule phospho-STAT5 (P-STAT5) in MOLM-13 cells in a dose-dependent manner. Furthermore, KW-2449 increases the percentage of cells in the G1 phase of the cell cycle and reciprocally reduces the percentage of cells in the S phase, resulting in the increase of apoptotic cell population. KW-2449 can dephosphorylate constitutively active WT-FLT3 kinase but not inhibit the proliferation of leukemia cells if they are not mainly addicted to FLT3 the kinase. ^[1] KW-2449 is rapidly absorbed and converted to a major metabolite M1.Preclinical studies reveal that KW-2449 is converted by monoamine oxidase-B (MAO-B) and aldehyde oxidase into its major metabolite M1.KW-2449 mediates cytotoxicity thru inhibition of FLT3/ITD.KW-2449 is a direct inhibitor of FLT3 and induces inhibition of its downstream target STAT5. ^[2] KW2449 interacts synergistically with HDACIs to induce apoptosis in Ph+ CML cells in a time- and concentration-dependent manner. KW2449 synergistically enhances the lethality of vorinostat/SNDX275 in CML cells.KW-2449 regimens are active against additional IM-resistant Bcr/Abl⁺ leukemia cells. KW2449 moderately reduces phosphorylation of histone H3, an indicator of Aurora B activity, in nocodozole-treated K562 cells. ^[3]