Discovery of BBO-11818, a Potent and Selective Noncovalent Inhibitor of (ON) and (OFF) KRAS with Activity against Multiple Oncogenic Mutants.

Although KRASG12C-specific inhibitors have been introduced, no approved targeted therapies exist for other clinically significant KRAS mutants, including KRASG12D and KRASG12V. We discovered BBO-11818, a potent, selective, orally bioavailable noncovalent pan-KRAS inhibitor capable of targeting multiple KRAS mutants in both the inactive GDP-bound (OFF) and active GTP-bound (ON) states. BBO-11818 binds in the Switch-II/Helix 3 pocket, inducing conformational changes incompatible with effector binding, and demonstrates high-affinity binding to mutant KRAS with strong selectivity over NRAS and HRAS. BBO-11818 potently inhibited MAPK signaling and cellular viability specifically in KRAS-driven lines and produced tumor regressions in KRAS-mutant xenograft models. Combination studies with anti-PD-1, anti-EGFR antibodies, and a RAS:PI3Kα breaker compound showed enhanced efficacy. BBO-11818 has entered phase I clinical trials for patients with various KRAS mutations in colorectal, pancreatic, and lung cancers (NCT06917079). SIGNIFICANCE: We discovered BBO-11818, a potent and selective noncovalent KRAS inhibitor with activity against multiple KRAS mutants in both the active (ON) and inactive (OFF) states. BBO-11818 addresses the need for KRAS inhibitors targeting clinically relevant mutants such as KRASG12D and KRASG12V, either as monotherapy or in combination.