NCT-58 is a potent inhibitor of C-terminal HSP90. NCT-58 does not induce the heat shock response (HSR) due to its targeting of the C-terminal region and elicits anti-tumor activity via the simultaneous downregulation of HER family members as well as inhibition of Akt phosphorylation. NCT-58 kills Trastuzumab-resistant breast cancer stem-like cells. NCT-58 induces apoptosis in HER2-positive breast cancer cells[1].

NCT-58 treatment (0.1-20 μM; 72 hours) dose-dependently reduces cell viability in HER2-positive BT474 and SKBR3 cells[1]. NCT-58 treatment (0.1-10 μM; 72 hours) increases the number of early and late apoptotic cells in HER2-positive BT474 and SKBR3 cells[1].NCT-58 treatment (2-10 μM; 72 hours) effectively reduced the levels of truncated p95HER2 and its phosphorylated form, as well as downregulation of Akt and phospho-Akt (Ser473) protein contents in JIMT-1 and MDA-MB-453 cells[1].

NCT-58 (30 mg/kg; i.p.; every other day for 47 days) suppresses Trastuzumab-resistant tumor growth[1].NCT-58 (30 mg/kg; i.p.; every other day for 47 days) causes a significant impediment of tumor growth and a marked decrease in tumor weight[1].

[1]. Park S, et al. The C-terminal HSP90 inhibitor NCT-58 kills trastuzumab-resistant breast cancer stem-like cells. Cell Death Discov. 2021;7(1):354.