Polθ-IN-10

Polθ-IN-10 is an inhibitor of Polθ-pol with a human IC50 of 1.3 nM, and it exhibits oral bioavailability in both mice and rats. It binds to an allosteric site on Polθ-pol, disrupting the microhomology-mediated end joining DNA repair pathway, and inhibits CYP2C9 with an IC50 of 1.63 μM. Polθ-IN-10 selectively inhibits the proliferation of HR-deficient cancer cells and induces apoptosis. This compound is suitable for research on HR-deficient cancers.

CYP2C9:1.63 μM

Polθ-IN-10 (Compound 20) effectively and selectively inhibits human Polθ polymerase activity with an IC50 of 1.3 nM, without affecting other human DNA polymerases at 10 μM. It selectively suppresses the proliferation of HR-deficient cancer cell lines with IC50 values between 2.49 and 5.60 μM, showing minimal impact on HR-proficient cancer and normal cell lines. Preferential inhibition of CYP2C9 is observed with an IC50 of 1.63 μM, and there is weak inhibition of other CYP subtypes; no inhibition of CYP1A2 is seen up to 50 μM. Polθ-IN-10 inhibits colony formation of HR-deficient MDA-MB-436 cells in a dose-dependent manner, with no significant effect on normal MCF10A cells. In HR-deficient MDA-MB-436 cells, it induces apoptosis dose-dependently, triggers time and dose-dependent DNA damage, and binds directly to Polθ protein to enhance its thermal stability. Demonstrating excellent metabolic stability in liver microsomes from humans, mice, and rats, Polθ-IN-10 has a half-life ranging from 121.6 to 247.5 minutes. Additionally, it exhibits weak inhibition of the hERG channel with only a 24.0% inhibition rate at 30 μM, indicating favorable cardiac safety characteristics.

Polθ-IN-10 (Compound 20) (administered orally at 25-100 mg/kg; single dose; over 28 days) significantly inhibits the growth of MDA-MB-436 xenograft tumors in a dose-dependent manner, achieving a maximum tumor growth inhibition (TGI) of 61.14% at the 100 mg/kg dose without noticeable in vivo toxicity.