A pan-KRAS inhibitor and its derived degrader elicit multifaceted anti-tumor efficacy in KRAS-driven cancers

KRAS remains a challenging therapeutic target with limited effective inhibitors currently available. Here, we report the discovery of MCB-294, a potent dual-state pan-KRAS inhibitor capable of binding both the active (GTP-bound) and inactive (GDP-bound) forms of KRAS. MCB-294 engages the switch-II pocket through a water-mediated hydrogen-bond network and selectively inhibits KRAS over NRAS and HRAS. It effectively suppresses oncogenic KRAS signaling, inhibits the growth of KRAS-dependent cancer cells and patient-derived organoids, and reduces tumor progression in multiple preclinical models. MCB-294 also demonstrates superior activity compared to the inactive-state selective pan-KRAS inhibitor Bl-2865 and the KRASG12D inhibitor MRTX1133. Building upon MCB-294 as a pan-KRAS-targeting warhead, we further develop MCB-36, a von Hippel-Lindau (VHL)-recruiting pan-KRAS degrader that induces sustained KRAS degradation. Notably, both MCB-294 and MCB-36 effectively suppress KRASG12C inhibitor-resistant cancer cells and remodel the tumor immune microenvironment. These findings highlight a promising therapeutic strategy for broadly targeting KRAS-driven tumors and overcoming drug resistance.