Lomeguatrib is a O⁶-methylguanine-DNA methyltransferase (MGMT) inhibitor, with IC₅₀s of 9 nM in cell-free assay and ∼6 nM in MCF-7 cells. IC50 & Target: IC50: 9 nM (MGMT)^[1], ∼6 nM (MGMT, MCF-7 cells)^[2] In Vitro: Lomeguatrib (Compound 10) is a O⁶-methylguanine methyltransferase (MGMT) inhibitor, with an IC₅₀ of 9 nM in cell-free assay^[1] and ∼6 nM in MCF-7 cells. Lomeguatrib (10 μM) substantially increases the growth inhibitory effects of temozolomide in MCF-7 cells (D₆₀=10 μM with Lomeguatrib vs 400 μM without)^[2]. In Vivo: Lomeguatrib (20 mg/kg i.p.) completely inactivates MGMT within 2 h, but shows no significant effect on tumor growth in MCF-7 xenografts^[2].