Abstract A109: Targeting pyrimidine biosynthesis as a metabolic vulnerability in brain metastasis

Abstract Metastasis, the spread of cancer cells from one part of the body to another, is the leading cause of death among cancer patients. Lung-to-Brain metastasis remains a largely understudied disease that possesses a dismal prognosis due to the lack of effective therapies. We previously identified purine metabolism as a metabolic vulnerability of brain metastases.  Here, we sought to identify whether pyrimidine biosynthesis is also a metabolic dependency of metastatic brain tumours.  We identify dihydroorotate dehydrogenase (DHODH) as a cancer-selective targetable vulnerability.  DHODH is an essential enzyme that is located within the inner membrane of the mitochondria which has a primary role in producing pyrimidine metabolites through the de novo uridine biosynthesis pathway and also contributes to the proper functioning of the electron transport chain.  Knock-out of DHODH with CRISPR-Cas9 or pharmacological inhibition with BAY2402234 decreased cell viability, sphere formation, and proliferation of patient-derived lung-to-brain (LBM) metastasis cells in vitro. Furthermore, suppression of DHODH expression or BAY2402234 treatment reduced growth of intracranial LBM tumours and significantly extended survival.  Mechanistically, we identify interfering with DHODH activity abrogates normal mitochondrial function leading to cleavage of gasdermin E and induction of pyroptosis. Taken together, this study highlights the promise of DHODH inhibitors in targeting brain metastasis. Citation Format: Daniel Mobilio, Sheila K Singh, Shawn C Chafe. Targeting pyrimidine biosynthesis as a metabolic vulnerability in brain metastasis [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A109.