KW-2478

KW-2478 is a novel non-ansamycin potent Hsp90 inhibitor with an IC50 of 3.8 nM. KW-2478 is a novel non-purine analogue antagonist for Hsp90. KW-2478 suppressed the binding of bRD to HSP90α in concentration-dependent manner. KW-2478 indicated a potent anti-cancer activity both in vitro and in vivo. KW-2478 clearly prevented cancer cell growth in all cell lines, with EC50 of 101-252, 81.4-91.4 and 120-622 nM for B-cell lymphoma, mantle cell lymphoma and multiple myeloma, respectively. KW-2478 also showd potent growth inhibitory activity in primary CLL (n=3) and NHL (n=2) cells with EC50 of 40-170 nM and 200-400 nM, respectively. KW-2478 depleted the Hsp90 client Cdk9, a transcriptional kinase, and the phosphorylated 4E-BP1, a translational inhibitor. Both inhibitory effects of KW-2478 on such transcriptional and translational pathways were shown to reduce c-Maf and cyclin D1 expression. In NCI-H929 s.c. inoculated model, KW-2478 displayed a significant inhibition of tumor growth and induced the degradation of client proteins in tumors.