Abstract 5743: Discovery of a novel orally available microtubule-destabilization agent that targets the colchicine binding site and exhibits antitumor activity in <i>KRAS</i> -mutant models

Abstract Background: Microtubules are essential for regulating cell growth, cell division, protein trafficking, and key cell signaling events. Alterations to the microtubule network affect cell survival, thus making microtubule-targeting agents desirable as cancer therapeutic agents. Currently, several tubulin modulators are approved for cancer treatment. However, development of additional microtubule-targeting agents is still needed to improve treatment outcomes, mitigate side effects, and overcome resistance mechanisms. Here, we describe compound A, a novel, orally available microtubule-destabilizing agent that targets the colchicine binding site and exhibits single-agent antitumor activity in KRAS-mutant models. Methods: Inhibition of tubulin polymerization was measured using a recombinant polymerization assay and a cell-based microtubule sedimentation assay. Binding to the colchicine site of tubulin was determined by a binding competition assay using a BODIPY-colchicine probe. Disruption of tubulin formation was determined by immunofluorescence of microtubules in A549 cells. Compound binding to the tubulin complex was determined via X-ray crystallography. Cellular proliferation of KRAS-mutant and isogenic cell lines was measured using resazurin. KRAS-mutant mouse xenograft models were used to assess pharmacokinetics (PK), pharmacodynamics, and antitumor activity. Results: Compound A binds to the colchicine site and destabilizes tubulin polymerization. Treatment resulted in single-agent inhibition of proliferation of KRAS-mutant cancer cell lines. Immunofluorescence of microtubules in A549 cells revealed disruption of the microtubule network and dysregulated spindle formation. Compound A exhibited a favorable ADME and PK profile. Oral treatment of compound A as a single agent resulted in 56% tumor growth inhibition in a subcutaneously implanted KRAS-mutant lung xenograft model. Conclusions: Compound A is an orally bioavailable tubulin modulator that binds to the colchicine site and inhibits tumor growth in a KRAS-mutant model as a single agent. Our preclinical data provide proof of concept for the development of an orally available microtubule-destabilizing agent. Citation Format: Yeni K. Romero, Joshua W. Large, Kylie Luther, Molly M. Hood, Ranjan Preet, Chase K. Crawley, Salim Javed, Yu Mi Ahn, Forrest A. Stanley, Bertrand Le Bourdonnec, Bryan D. Smith, Daniel L. Flynn, Jeffery D. Zwicker, Stacie L. Bulfer. Discovery of a novel orally available microtubule-destabilization agent that targets the colchicine binding site and exhibits antitumor activity in KRAS-mutant models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5743.