Alvespimycin

Alvespimycin (17-DMAG; KOS-1022; NSC 707545) is a potent, water-soluble Hsp90 inhibitor with IC50 of 62 nM. 17-DMAG displays ~2 times potency against human Hsp90 than 17-AAG, with IC50 of 62 nM versus 119 nM. In SKBR3 and SKOV3 cells which overexpress Hsp90 client protein Her2, 17-DMAG causes down-regulation of Her2 with EC50 of 8 nM and 46 nM, respectively, as well as induction of Hsp70 with EC50 of 4 nM and 14 nM, respectively, leading to significant cytotoxicity with GI50 of 29 nM and 32 nM, respectively, consistent with Hsp90 inhibition. In combination with vorinostat, 17-DMAG synergistically induces apoptosis of the cultured MCL cells as well as primary MCL cells, more potently than either agent alone, by markedly attenuating the levels of cyclin D1 and CDK4, as well as of c-Myc, c-RAF and Akt. 17-DMAG treatment at 5 mg/kg or 25 mg/kg three times per week significantly reduces tumor growth of TMK-1 xenografts, by reducing vessel area and numbers of proliferating tumor cells in sections. Consistent the inhibition of FAK signaling in vivo, 17-DMAG treatment at 25 mg/kg three times a week significantly suppresses tumor growth, and metastasis of ME180 and SiHa xenografts in mice. Administration of 17-DMAG at 10 mg/kg for 16 days significantly decreases the white blood cell count and prolongs the survival in a TCL1-SCID transplant mouse model.