In Vitro: STAT3-IN-13 (compound 6f) (48 hours) has anti-proliferative activity with IC50 values of 0.25, 0.11 and 0.55 μM for 143B, HOS and MG63 cells, respectively. STAT3-IN-13 (compound 6f) (0.001-100 μM) binds to STAT3 and interacts with STAT3586−685 in a concentration dependent manner with a KD of 0.96 μM. STAT3-IN-13 (compound 6f) (0-1.0 μM; 24 hours; 143B and HOS cells) inhibits STAT3 Y705 phosphorylation and suppresses STAT3 in tumor cells. STAT3-IN-13 (compound 6f) (0-1.0 μM; 48 hours; 143B cells) induces apoptosis in a dose-dependent manner.
In Vivo: STAT3-IN-13 (compound 6f) (10-20 mg/kg; i.p.; twice daily, for 4 weeks; nude mice) blocks osteosarcoma growth and metastasis in vivo.