Saturday, September 12, 2015

Drugs in Clinical Pipeline: KW-2449

KW-2449 [(E)-(4-(2-(1H-indazol-3-yl)vinyl)phenyl)(piperazin-1-yl)methanone] is an orally available multikinase inhibitor of FMS-like receptor tyrosine kinase (FLT3), ABL, ABL-T315I, and Aurora kinase. It is currently in Phase I trials for leukemia patients. KW-2449 inhibited FLT3 and ABL kinases with half-maximal inhibitory concentration (IC50) values of 0.0066 and 0.014 µM, respectively. In addition, it potently inhibited ABL-T315I, which is associated with IM resistance, with an IC50 value of 0.004 µM. On the other hand, KW-2449 had little effect on PDGFRβ, IGF-1R, EGFR, and various serine/threonine kinases even at a concentration of 1 µM. Among various serine/threonine kinases examined, KW-2449 inhibited Aurora A kinase with IC50 of 0.048 µM and Aurora B kinase with the equivalent potency.

The researchers at Kyowa Hakko Kirin (previously Kyowa Hakko Kogyo) aimed at designing an orally available and highly potent FLT3 inhibitor with low toxicity profile for leukemia patients. For this goal, they screened the in-house chemical libraries using several leukemia cells, which have several activated mutations in FLT3 or BCR-ABL translocation. As a result, they identified several chemo-types with different kinase inhibition profiles, intensively studied the structures of the identified chemo-types to improve the potency and selectivity, and then finally generated KW-2449 [1].

Preclinical studies revealed that KW-2449 is converted by monoamine oxidase-B (MAO-B) and aldehyde oxidase into its major metabolite M1. Metabolite M1 is 3.6-fold less potent than the parent drug. The combination of KW-2449 and metabolite can successfully inhibit FLT3 in patients, and FLT3 mutant patients treated with KW-2449 on a twice daily schedule display the typical, short-lived reduction in peripheral blasts that has been seen with the other FLT3 inhibitors in development.

The activity of KW-2449 is as follows:

IC50 (FLT3 enzyme assay) = 0.0066 uM
IC50 (FLT3-D835Y enzyme assay) = 0.001 uM
IC50 (KIT enzyme assay) = 0.3 uM
IC50 (PDFGRα enzyme assay) = 1.7 uM
IC50 (ABL enzyme assay) = 0.014 uM
IC50 (ABL-T315I enzyme assay) = 0.004 uM
IC50 (SRC enzyme assay) = 0.4 uM
IC50 (JAK2 enzyme assay) = 0.15 uM
IC50 (FGFR1 enzyme assay) = 0.036 uM
IC50 (AURKA enzyme assay) = 0.048 uM

Common Name: KW-2449
Synonyms: KW2449; KW-2449; KW 2449
IUPAC Name: (E)-(4-(2-(1H-indazol-3-yl)vinyl)phenyl)(piperazin-1-yl)methanone
CAS Number: 1000669-72-6
Mechanism of Action: Kinase Inhibitor; FLT3 Inhibitor; ABL Inhibitor; Aurora Kinase Inhibitor; MultiKinase Inhibitor
Indication: Various Cancers; Leukemia
Development Stage: Phase I
Company: Kyowa Hakko Kirin Pharmaceuticals

FMS-like receptor tyrosine kinase (FLT3) is a class III receptor tyrosine kinase together with cKIT, FMS, and PDGFR. FLT3 mutations were first reported as internal tandem duplication (FLT3/ITD) of the juxtamembrane domain-coding sequence; subsequently, a missense point mutation at the Asp835 residue and point mutations, deletions, and insertions in the codons surrounding Asp835 within a tyrosine kinase domain of FLT3 (FLT3/KDM) have been found. FLT3 mutation is the most frequent genetic alteration in acute myeloid leukemia (AML) and involved in the signaling pathway of proliferation and survival in leukemia cells. Several large-scale studies have confirmed that FLT3/ITD is strongly associated with leukocytosis and a poor prognosis. In addition to FLT3 mutation, overexpression of FLT3 is an unfavorable prognostic factor for overall survival in AML, and it has been revealed that overexpressed FLT3 had the same sensitivity to the FLT3 inhibitor as FLT3/ITD [1]. Acute leukemia is a complex multigenetic disorder, a simultaneous inhibition of multiple protein kinases is thought to be advantageous over the increasing potency against the selective kinases.

In vitro kinase inhibition profile of KW-2449 indicated its extreme potency against FLT3 kinase. KW-2449 showed growth inhibitory activities against FLT3/ITD-, FLT3/D835Y-, and wt-FLT3/FL-expressing 32D cells, MOLM-13 and MV4;11 with half-maximal growth inhibitory concentration (GI50) values of 0.024, 0.046, 0.014, 0.024, and 0.011 µM, respectively [1].

1. Shiotsu, Y.; et. al. KW-2449, a novel multikinase inhibitor, suppresses the growth of leukemia cells with FLT3 mutations or T315I-mutated BCR/ABL translocation. Blood 2009, 114(8), 1607-1617.
2. Safety, Tolerability, and Pharmacokinetic/Pharmacodynamic Study of KW-2449 in Acute Myelogenous Leukemia (AML) (Protocol Number: 2449-US-002). NCT00779480. Retrieved (01-09-2015)
3. An Ascending Dose Study of KW-2449 in Acute Leukemias, Myelodysplastic Syndromes, and Chronic Myelogenous Leukemia. NCT00346632. Retrieved (01-09-2015)