Abstract A057: Cancer-induced epigenomic changes in circulating immune cells enable breast, colorectal and lung cancer detection

Abstract Background: Epigenomic changes via the measurement of 5-hydroxymethylation cytosine (5hmC) in DNA have been shown to enable detection in a variety of cancers including pancreatic and ovarian cancer in plasma-derived cell-free DNA (cfDNA). Here, we investigated whether blood-based 5hmC profiling of genomic DNA (gDNA) derived from cells of the buffy coat (BC) possess signals that enable the detection of breast, colorectal and lung cancers. Method: Blood samples collected in Streck tubes from cancer patients or non-cancer controls were processed to obtain buffy coat and plasma samples. gDNA and cfDNA was isolated from buffy coat and plasma, respectively. gDNA or cfDNA was then subjected to 5hmC enrichment by click chemistry followed by preparation of sequencing libraries. Sequencing was performed to obtain genome-wide 5hmC profiles of buffy coat gDNA and cfDNA samples. Results: Differential hydroxymethylation analysis of BC gDNA revealed increased 5hmC over genes associated with myeloid lineage in breast, colorectal and lung cancers relative to non-cancer controls. Flow cytometry analysis confirmed increases in myeloid cells in cancer samples relative to non-cancer controls. 5hmC patterns in BC gDNA showed a larger number of cancer-associated changes compared to cfDNA, in particular this was found in early-stage disease. 5hmC features from BC gDNA or plasma-derived cfDNA were used to build prediction models that yielded cancer classification with overall sensitivity of 51.3% and 52.6% at 98% specificity, for BC or cfDNA, respectively. For early-stage cancer, the sensitivity at 98% specificity was 46.5% for the BC and 28.2% for cfDNA model. A final prediction model incorporating features from both tissue sources achieved superior classification (65.8% sensitivity) at 98% specificity, compared with using features from either tissue source alone, particularly for early-stage cancer which achieved 53.5% sensitivity of cancer detection. Conclusion: Our results demonstrate that cancer impacts the 5hmC profiles of buffy coat cells which can be leveraged for cancer detection using blood. Citation Format: Gulfem D Guler, Giuliana P Mognol, Yuhong Ning, Carolina Fraire, David Haan, Michael Kesling, Roger Malta, Melissa Peters, Anna Bergamaschi, Tierney Phillips, Shimul Chowdhury, Wayne Volkmuth, Samuel Levy. Cancer-induced epigenomic changes in circulating immune cells enable breast, colorectal and lung cancer detection [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A057.