RUNX1/ETO-IN-1 is an inhibitor targeting the oncogenic fusion protein RUNX1-ETO, specifically affecting the NHR2 oligomerization domain. It binds directly to NHR2 (KD,app = 39 μM). By inducing apoptosis and promoting differentiation, RUNX1/ETO-IN-1 exhibits antileukemic activity in RUNX1/ETO translocation acute myeloid leukemia (AML) cells. Its near-neutral charge under physiological pH conditions grants it excellent cell membrane permeability.

RUNX1/ETO-IN-1 (Compound M23) exhibits an IC50 value of 62.14 µM in the SKNO-1 acute myeloid leukemia cell line carrying the t(8;21) translocation, which results in RUNX1/ETO fusion gene expression. At concentrations ranging from 20-200 µM, RUNX1/ETO-IN-1 decreases the thermal stability of the NHR2 domain (ΔTm = -1.6°C) in a concentration-dependent manner, possibly by disrupting the tetramer-dimer equilibrium. At 50-100 µM for 24 hours, it induces cell cycle arrest and potential apoptosis in SKNO-1 cells but has no such effect on THP-1 cells. Additionally, it enhances apoptosis in SKNO-1 cells by increasing the activity of caspase-3 and caspase-7, without affecting THP-1 and healthy control NC-NC cells. RUNX1/ETO-IN-1 also promotes differentiation in SKNO-1 cells by elevating CD11b expression at 25-50 µM over three days, an effect not observed in K562 and THP-1 cells.