Archival single cell sequencing reveals persistent subclones over years to decades of DCIS progression

Abstract Ductal carcinoma in situ (DCIS) is a common precursor of invasive breast cancer (IBC), yet the genomic progression to recurrent disease remains poorly understood. A main contributor to this gap in knowledge arises from technical challenges with genomic profiling of formalin-fixed paraffin-embedded (FFPE) materials. To address this challenge, we developed Arc-well, the first high-throughput method that can perform single cell DNA sequencing of thousands of cells from FFPE materials and frozen tissues. Using Arc-well, we profiled genomic copy number in 27,851 single cells from 26 archival FFPE tissues that were stored for 3-31 years. Analysis of genomic evolution in 10 patients with matched DCIS and recurrent cancers (DCIS or IBC) separated by 2-16 years showed that many primary DCIS lesions had already undergone whole-genome-doubling and had extensive clonal diversity, similar to the paired recurrence. The data from most patients (8/10) suggest an evolutionary bottleneck model of progression, in which a single subclone persisted during the progression to the recurrent disease, revealing copy number aberrations associated with invasion and recurrence. Citation Format: Kaile Wang, Tapsi Kumar, Junke wang, Darlan Minussi, Emi Sei, Jianzhuo li, Tuan Tran, Aatish Thennavan, Min Hu, Anna Casasent, Zhenna Xiao, Shanshan Bai, Yuehui Zhao, Amado Zurita, Ana Aparicio, Brian Chapin, Jie ye, Jianjun Zhang, Don Gibbons, Andrew Futreal, Lorraine King, Jeffrey Marks, E. Shelley Hwang, Vandna Shah, Ellinor Sawyer, Petra Kristel, Jelle Wesseling, Esther H. Lips, Nicholas Navin. Archival single cell sequencing reveals persistent subclones over years to decades of DCIS progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 125.