Design, Synthesis, and Pharmacological Evaluation of Multisubstituted Pyrido[4,3-d]pyrimidine Analogues Bearing Deuterated Methylene Linkers as Potent KRASG12D Inhibitors

The breakthrough in drug development of KRAS^G12C inhibitors provides inspiration for targeting alternative KRAS mutations, especially the most prevalent KRAS^G12D variant. Based on the structural analysis of MRTX1133 in complex with KRAS^G12D, a comprehensive structure-activity study was conducted, which led to the discovery of several compounds (22, 28, and 31) that showed higher potency in suppressing the clonogenic growth of KRAS^G12D-dependent cancer cells. These new compounds markedly and selectively inhibited the binding of RBD peptide to GTP-bound KRAS^G12D with IC₅₀ values between 0.48 and 1.21 nM. These new inhibitors were found to have dose-dependent anti-tumor efficacy in the AsPC-1 xenograft mouse models with a tumor growth inhibition of approximately 70% at a dose of 20 mg/kg twice daily (i.p.). Despite the non-optimal pharmacokinetic properties similar to those of MRTX1133, the high in vitro and in vivo potency of these new inhibitors call for further profiling.