Archived

This content is available here strictly for research, reference, and/or recordkeeping and as such it may not be fully accessible. If you work or study at University of Kentucky and would like to request an accessible version, please use the SensusAccess Document Converter.

Abstract

The presence of BRAF V600E mutations is associated with poor prognosis in colorectal cancer (CRC). Although the FDA-approved combination of encorafenib and cetuximab provides clinical benefit in this population, only 22% of patients respond and most eventually develop resistance. This study investigated the mechanisms of resistance to PLX8394, a second-generation BRAF inhibitor. Using primary and established BRAF V600E CRC cells, we show that the development of resistance to PLX8394 results in cross-resistance of cells to encorafenib. Moreover, the acquired resistance is associated with increased proliferation, invasion, and upregulation of lipid metabolism, including increased expression of fatty acid synthase (FASN), a key enzyme of lipid synthesis. Yet, the combination of PLX8394 and FASN inhibitor TVB3664 has a synergistic effect on cell viability and colony formation in parental CRC cells, but not in PLX-resistant cells. Importantly, we demonstrate that addition of TVB3664 to the PLX8394 or encorafenib regimen significantly postpones development of resistance to BRAF-targeted therapy by inhibiting the cell cycle progression via a decrease in pRb (Ser780) and downregulation of E2F transcription factor and Cyclin D1 expression. Consistently, clinical data show that patients with BRAF V600E CRC who have high FASN expression in tumor tissues have higher expression of cell cycle-associated genes, including CDKs, E2F, CCDN1 (Cyclin D1), survivin, and MKI67. Collectively, these findings identify FASN-driven lipid metabolism as a critical mediator of resistance to BRAF-targeted therapy and suggest that incorporation of FASN inhibitors may enhance therapeutic efficacy and delay acquired resistance in BRAF V600E CRC

Document Type

Article

Publication Date

2026

Notes/Citation Information

1476-5586/© 2026 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).

Digital Object Identifier (DOI)

https://doi.org/10.1016/j.neo.2026.101283

Funding Information

This work is supported by National Cancer Institute training grant T32 CA165990 (MEG) and R01 CA249734 (YYZ), and by Colorectal Cancer Alliance Project Cure CRC Pilot Award (YYZ).

Download

Share

COinS