Abstract 1878: Cotargeting B-Raf and ACLY in Ras mutant cells leads to synergistic loss of cell viability and apoptosis.

Abstract Ras mutation is found in several tumor types including pancreatic and colon cancer. Downstream from Ras is the B-Raf kinase, also often found mutated in tumor cell types such as melanoma. B-Raf inhibitors Vemurafenib, Dabrafenib and Encorafenib are used clinically in combination with MEK inhibitors Trametinib, Cobimetinib and Binimetinib. Together, these agents serve to inhibit the MAPK pathway, but the PI3K/AKT pathway is often upregulated leading to treatment resistance. AKT functions in numerous cellular processes including metabolism. In fact, AKT activates lipogenesis by direct phosphorylation and activation of the enzyme ATP-Citrate Lyase (ACLY). ACLY expression and activity are elevated in various cancer cell types. A new inhibitor of ACLY, NDI-091143, was recently identified based on the structure of ACLY and was used in this study. A panel of Ras mutant cell lines was used to investigate the effect of combining the ACLY inhibitor NDI-091143 with the BRAF inhibitor Vemurafenib on cell proliferation and apoptosis. Using concentrations of each drug that reduced cell viability individually by 25%, we found that the combination exhibited synergistic reduction of cell viability in Ras mutant A375 melanoma cells, MDA-MB-231 breast cancer cells, MIA Paca-2 pancreatic cancer cells and HCT116 colon cancer cells. Cancer cells with WT Ras such as MeWo melanoma and T47D breast cancer showed no synergistic loss of viability in response to the combination. Non-transformed cells such as colon epithelial (CCD-18Co) and normal pancreatic cells (H6c7) are unaffected by the same concentrations used in the Vemurafenib and NDI-091143 combination treatment. The mechanism of reduction in viability appears to be due to activation of apoptosis. All four Ras mutant cell lines showed increased expression of cleaved PARP and the activation of the ER stress pathway regulator ATF4. Finally, the apoptosis stimulated by the combination was shown to be dependent on Caspase-3 activity using Annexin V analysis of HCT116 cells treated with Vemurafenib plus NDI-091143. Citation Format: Nancy A. Krucher, Bryce D. Aierstok, Sabrina Bergesio, Gabriella J. Galgano, Morgan E. Strecker. Cotargeting B-Raf and ACLY in Ras mutant cells leads to synergistic loss of cell viability and apoptosis 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 1878.