666-15

666-15 is a potent and selective inhibitor of cyclic adenosine monophosphate response element binding protein (CREB)-mediated gene transcription with an IC₅₀ of 81 nM. The IC₅₀ values for inhibiting the growth of A549, MCF-7, MDA-MB-231, MDA-MB-468 cell lines are 0.47 μM, 0.31 μM, 0.073 μM, 0.046 μM respectively. It is a weak inhibitor of CREB-CBP (CREB-binding protein) interaction with an IC₅₀ of 18.27 μM. Intraperitoneal injection of 666-15 at 10 mg/kg/day, 5 days per week for 5 weeks suppresses tumor growth in an in vivo MDA-MB-468 xenograft model.