A pan-KRAS inhibitor and its derived degrader elicit multifaceted anti-tumor efficacy in KRAS-driven cancers [scRNA-seq]
KRAS is the most frequently mutated oncogene in human cancers, but to date, only KRASG12C inhibitors have been FDA-approved. Small-molecule inhibitors that target other more prevalent KRAS mutations are in urgent clinical need. Here, we report a highly potent pan-KRAS inhibitor, MCB-294, that selectively targets KRAS, but not HRAS or NRAS. Molecular profiling studies show that MCB-294 binds to and inhibits several KRAS mutants, including G12D, G12C, G12V, thereby disabling KRAS oncogenic signaling. MCB-294 is well tolerated in mice and exhibits remarkable therapeutic efficacy against the growth of a comprehensive range of KRAS-driven cancer cell lines, patient-derived organoids, and tumor xenografts and prolongs mouse survival. By employing an MCB-294 derivative as the KRAS binder, we further identify a VHL-based pan-KRAS degrader, MCB-36, that efficiently degrades KRAS in vitro and in vivo through the ubiquitin-proteasome system. Importantly, MCB-294 and MCB-36 not only effectively kill KRASG12C inhibitor-resistant cells, but also reshape the tumor microenvironment by boosting T cell-mediated anti-tumor immunity. Taken together, our findings demonstrate a successful and feasible strategy for targeting pan-KRAS to impair multifaceted features of KRAS-driven cancers. Overall design: To investigate the  effects of MCB-294 or MCB-36 on the modulation of the tumor microenvironment, CT26 xenografts treatment with vehicle, MCB-294 or MCB-36 compound for 2 days were harvested, and then analyzed using sc-RNAseq.