Abstract PO3-16-05: Mitochondrial DNA mutation detection in tumors and circulating extracellular vesicles of triple negative breast cancer patients for biomarker development

Abstract Early detection of triple-negative breast cancer (TNBC) patients and their recurrence prediction are daunting tasks. We aim to develop mitochondrial DNA (mtDNA) based biomarkers to improve the management strategies of TNBC patients. We have undertaken mitochondrial genome (MG) enrichment and next-generation sequencing approaches to map the entire MG in 73 samples (64 tissues, 9 extracellular vesicle samples) from 32 highly-aggressive TNBC patients. Measurement of mtDNA and cardiolipin contents, in concert with NDUFB8 and SDHB proteins’ expression, was carried out in tumors and matched extracellular vesicles (EVs) of all the above TNBC patients. Overall, we identified 168 nonsynonymous mtDNA mutations, of which 73% (123/186) were coding and 27% (45/168) were non-coding. Twenty percent of mutations were nucleotide transversions. Respiratory complex I (RCI) appears to be the key target, which harbored 44% (74/168) of the overall mtDNA mutations. A panel of 11 hotspot mtDNA mutations was identified among 19-38% TNBCs, each of which was detectable in the matched EV samples with 82% specificity. Overall, 38% of the metastatic tumor-signature mtDNA mutations were detectable in matched EVs of the TNBC patients. An appreciable number of mtDNA mutations were homoplasmic (18%, 31/168), novel (14%, 23/168), and potentially pathogenic (9%, 15/168). The overall and RCI-specific mtDNA mutational load was recorded to be higher in African American (AA) compared to European American (EA) women with an exclusive abundance of respiratory complex (RC) protein NDUFB8 (RCI) and SDHB (RCII) therein. Increased mtDNA (p 0.0001) content was measured in both tumors and matched EV samples along with an abundance of cardiolipin (p=0.0001) content in the EVs of the TNBC patients. Lethal tumor-signature mtDNA mutation detection and measurement of altered mtDNA and cardiolipin contents in the EVs at an early time point bear the potential to formulate noninvasive early detection and recurrence prediction strategies in TNBCs to improve the overall survival of the patients. Citation Format: Kunwar Vikramdeo, Shashi Anand, Sarabjeet Sudan, Paramahansa Pramanik, Seema Singh, Andrew Godwin, Ajay Singh, Santanu Dasgupta. Mitochondrial DNA mutation detection in tumors and circulating extracellular vesicles of triple negative breast cancer patients for biomarker development abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-16-05.