NMS-E973 is a potent and selective Hsp90 inhibitor with a DC50 of less than 10 nM for Hsp90 binding, displaying no activity against a panel of 52 diverse protein kinases.

HSP90:<10 nM(DC50)

NMS-E973 shows a widespread antiproliferative activity with an average IC50 of 1.6 μM, and induces the degradation of client protein, such as Flt3, B-Raf, AKT, which further blocks tumor-related pathways, such as the Raf/MAPK, PI3K/AKT, and JAK/STAT pathways. [1]

NMS-E973 (10 mg/kg i.v.) shows a favorable pharmacokinetic profile with selective retention in tumor tissue and ability to cross the BBB. NMS-E973 (60 mg/kg i.v.) shows high antitumor efficacy in all the models tested, including A375 and A2780 xenografts. In addition, NMS-E973 (10 mg/kg i.v.) together with B-Raf inhibitor PLX-4720 at 100 mg/kg produces a synergic anti-tumor effect. [1] In a mouse model of human ovarian cancer, NMS-E973 produces the antitumor activity by inhibition of Hsp90. [2]

Hsp90 binding assays: For competition experiments, a protein concentration of 5 nM for Hsp90 and of 200 nM for Trap1 are mixed with 0.5 nmol/L probe (final concentrations). After incubation, the dimethyl sulfoxide (DMSO) compound solution is added to the mixture. The plate is incubated for 18 hours at room temperature and then the fluorescence polarization signal was measured. Data are fitted with the program Dynafit version 3.28.039 or SigmaPlot (SSI) using the mathematical equation for competitive binding of 2 ligands to the receptor.