Design and Evaluation of Bivalent K‐Ras Inhibitors That Target the CAAX Binding Site and the Acidic Surface of Farnesyltransferase and Geranylgeranyltransferase I

Abstract Mutant K‐Ras drives cancer through its membrane localization, which requires posttranslational modification by farnesyltransferase (FTase). FTase attaches farnesyl to the K‐Ras C‐terminal CVIM tetrapeptide, enabling membrane binding. However, K‐Ras can also undergo compensatory geranylgeranylation by geranylgeranyltransferase I (GGTase I), making FTase inhibition alone ineffective. Dual inhibition of FTase and GGTase I is necessary to fully block K‐Ras localization and its cancer activity. We developed bivalent inhibitors targeting both FTase and GGTase I by binding to the CVIM (C = cysteine, V = valine, I = isoleucine, M = methionine) site and an adjacent acidic surface. A nonthiol CVIM peptidomimetic based on a piperidine scaffold showed potent FTase inhibition ( K i = 2.1 nM) with less effect on GGTase I ( K i = 210 nM). Adding cationic modules to this compound produced dual inhibitors with enhanced potency ( K i = 2–5 nM), significantly improving upon previous agents. These bivalent inhibitors effectively reduced mutant K‐Ras cancer cell viability and inhibited K‐Ras farnesylation and geranylgeranylation in cells. This dual‐targeting approach shows promise for treating K‐Ras‐driven cancers.