Discovery of KRas G12C-IN-3 and Pomalidomide-based PROTACs as degraders of endogenous KRAS G12C with potent anticancer activity

A series of KRAS G12C-targeting PROTACs (PROteolysis TArgeting Chimeras) were designed and synthesized based on KRas G12C-IN-3 (a KRAS G12C inhibitor) and pomalidomide as degraders of KRAS G12C with a molecular weight of < 900. Among them, compound KP-14 (m.w. = 852.16; tPSA = 174.53) showed the highest KRAS G12C-degrading capability in NCI-H358 cancer cells (DC50≈1.25 μM). KP-14 bound to KRAS G12C through the acrylamide warhead and recruited the E3 ligase CRBN, causing rapid and sustained KRAS G12C degradation which led to suppression of MAPK signaling pathway in NCI-H358 cells. In addition, KP-14 selectively induced the degradation of KRAS G12C but not other KRAS isoforms such as G13D via PROTAC mechanism. Furthermore, KP-14 exhibited potent antiproliferative activity against NCI-H358 cancer cells and was able to suppress the formation of NCI-H358 tumor colonies. Collectively, this work suggests that KP-14 may serve as a tool compound for exploring the degradation of KRAS G12C by PROTAC strategy and deserve further investigation as a potential anticancer agent.