Discovery of Pyrazoloquinazoline Analogues as Orally Bioavailable KRAS-G12D Inhibitors

G12D is a dominant mutant of KRAS, accounting for 67.6% of PDAC cases, which drives the development of selective KRAS-G12D inhibitors in cancer therapy. Herein, we describe the rationale design, synthesis, and biological evaluation of KRAS-G12D inhibitors with pyrazoloquinazoline and 3,5-ethylene-bridged piperazine groups as the key pharmacophores. Compound 53a exhibited comparable binding to KRAS-G12D (ΔT_m = 12.1 °C) and potent in vitro activities (IC₅₀ values of 8.4 nM and 19.5 nM against p-ERK and proliferation of AsPC-1 cells, respectively), compared to those of MRTX1133 as a reference standard. Furthermore, compound 53a displayed appreciable plasma exposure, bioavailability, and pharmacokinetic profiles after oral administration, overcoming the poor oral bioavailability observed in MRTX1133. In vivo study showed that 53a significantly inhibited tumor growth in the AsPC-1 xenograft mouse model by inhibiting KRAS-G12D. These findings support 53a as a promising lead candidate for the development of selective KRAS-G12D targeted cancer therapies.