BBO-8520 is a direct small molecule covalent inhibitor targeting KRAS G12C with high oral availability. BBO-8520 has the characteristics of KRAS G12C (OFF) inhibitor and the function of blocking KRAS G12C (ON) signal. BBO-8520 inhibits cell proliferation by inhibiting KRAS G12C (ON) by binding GTP protein. BBO-8520 can block RAS-RAF1 interaction and return KRAS G12C to the inactive (OFF) state .