Alvespimycin (hydrochloride)

Alvespimycin hydrochloride (17-DMAG hydrochloride; KOS-1022; BMS 826476) is a potent inhibitor of Hsp90, binding to Hsp90 with EC₅₀ of 62±29 nM. IC50 & Target:EC50: 62 nM±29 nM (Hsp90)^[1] In Vitro: Alvespimycin hydrochloride (17-DMAG hydrochloride; KOS-1022; BMS 826476) inhibits the growth of the human cancer cell lines SKBR3 and SKOV3, which overexpress Hsp90 client protein Her2, and causes down-regulation of Her2 as well as induction of Hsp70 consistent with Hsp90 inhibition, for Her2 degradation with EC₅₀ of 8±4 nM and 46±24 nM in SKBR3 and SKOV3 cells, respectively; for Hsp70 induction with EC₅₀ of 4±2 nM and 14±7 nM in SKBR3 and SKOV3 cells, respectively^[1]. Compared with the vehicle control, 17-DMAG exerts dose-dependent apoptosis (P<0.001 averaged across 24- and 48-hour time points) at concentrations of 50nM to 500nM, which represent pharmacologically attainable doses. Similar to many other agents, 17-DMAG also demonstrates time-dependent apoptosis (P <0.001, averaged across all doses) in chronic lymphocytic leukemia (CLL) cells with extended exposure from 24 to 48 hours. In addition, 17-DMAG is much more potent after 24 and 48 hours of treatment than 17-AAG^[2]. In Vivo: The tumors are grown for two months before the start of i.p. injections every four days over one month with 0, 50, 100 and 200 mg/kg dipalmitoyl-radicicol or 0, 5, 10 and 20 mg/kg 17-DMAG. Despite sample heterogeneity, the HSP90 inhibitor-treated animals have significantly lower tumour volumes than the vehicle control-treated animals. HSP90 inhibitors have been shown to cause liver toxicity in an animal model of gastrointestinal cancer. Nevertheless, the reduction in tumor size using dipalmitoyl-radicicol is statistically significant at 100 mg/kg, while 17-DMAG at either 10 or 20 mg/kg elicited a significant reduction in tumor size^[3].