YZ-35 is a STAT3 inhibitor with a Ki value of 0.38 μM. It binds directly to STAT3 with high affinity, having a dissociation constant (Kd) of 190 nM. YZ-35 effectively inhibits the dual phosphorylation of STAT3 at Tyr705 and Ser727 sites. It also suppresses colony formation, cell migration, and induces apoptosis in breast cancer cell lines. Additionally, YZ-35 selectively inhibits the self-renewal capability of breast cancer stem cells (BCSC) and reduces tumor growth in breast cancer stem cell xenograft models. YZ-35 is applicable for breast cancer research.

YZ-35 demonstrates inhibitory potency against MDA-MB-231 cells (IC50 = 0.63 μM), MCF-7 cells (IC50 = 0.32 μM), and MCF-10A cells (IC50 = 34.34 μM) at concentrations ranging from 0.1 to 100 μM over 48 hours. At concentrations between 0 and 4 μM for 0 to 48 hours, YZ-35 exhibits significant anti-breast cancer activity in MDA-MB-231 and MCF-7 cells by directly reducing dual phosphorylation of STAT3 (Tyr705 and Ser727). Additionally, YZ-35, at doses of 0 to 6 μM for 24 to 48 hours, inhibits colony formation and cell migration while inducing apoptosis in MDA-MB-231 and MCF-7 cells. Furthermore, within the range of 2.5 to 10 μM for 48 hours, YZ-35 reduces tumor stemness in these cells.

YZ-35 (5-10 mg/kg, administered intravenously, once daily for 21 days) inhibits tumor growth in BCSC xenograft models.