Discovery of potent KRASG12D inhibitors disrupting RAS-Raf interaction to block activation

The proteins encoded by the KRAS gene belong to the RAS family, with activating KRAS mutations strongly implicated in oncogenesis. The hard-to-target nature of KRAS proteins stems from their unique structural biology: a highly conserved spherical surface lacking deep hydrophobic binding pockets, topologically flat ligand-binding interfaces, and picomolar affinity for GTP/GDP. These features-combined with rigid conformational constraints- prevent effective competitive binding by traditional small molecule inhibitors, constituting the structural basis for the long-term ‘undruggable’ of this target. Recent breakthroughs have been made in the research of KRAS inhibitors, among which the research on KRAS G12D has identified the compound KAL-21404358 and its P110 allosteric site to block KRAS activity. This groundbreaking discovery opens up entirely new directions for the development and design of novel drugs targeting KRAS. Using KAL-21404358 as lead, we developed the quinoline derivative WY-038 with enhanced KRAS G12D affinity ( K D 10.11 × 10 −6 M vs 10.72 M). Based on its better affinity and considering the effect of KRAS on downstream cRaf, subsequent structure-based optimization yielded novel quinoline analogs targeting KRAS G12D -cRaf inhibition, finding some of them with better inhibition rates. Compound C42 demonstrated potent activity against KRAS-driven cell lines, with IC 50 values of 13.42 ± 2.56 μM (LOVO), 12.55 ± 1.92 μM (NCIH-1385), 5.30 ± 1.23 μM (AsPC-1) and 6.84 ± 1.94 μM (PANC-1), respectively. Notably, C42 showed exceeded cisplatin's potency in AsPC-1 cells (5.30 ± 1.23 μM vs 6.54 ± 2.20 μM), and concentration-dependently suppressed KRAS-mediated PI3K/AKT and ERK1/2 signaling, inducing S-phase arrest in AsPC-1 cells. These findings establish compound C42 as a promising candidate for development and provide new perspectives for KRAS G12D -cRaf-targeted anticancer agents. • Optimized from lead KAL-21404358, WY-038 exhibits enhanced KRAS G12D affinity ( K D : 10.11 × 10 −6 M vs 10.72 M). • Structure-based design yielded novel quinoline C42, a KRAS G12D -cRaf inhibitor. • C42 potently inhibits KRAS-driven cells (IC 50 : 5.30 ± 1.23 μM AsPC-1, 6.84 ± 1.94 μM PANC-1, 12.55 ± 1.92 μM NCIH-1385, 13.42 ± 2.56 μM LOVO). • In AsPC-1, C42 surpasses cisplatin (5.30 ± 1.23 μM vs 6.54 ± 2.20 μM), blocks PI3K/AKT & ERK1/2 pathways dose-dependently, and induces S-phase arrest.