Abstract A011: Detection of disseminated tumor cells in advanced clear cell renal cell carcinoma through research autopsy
Authors: Yan Haixi , Martin Cristina Cotobal , English Christie , Verfaillie Annelien , Demeulemeester Jonas , Rowan Andrew , Fendler Annika , Cattin Anne-Laure , Mahapatra Sucheta , Au Lewis , Shepherd Scott , Shum Ben , Spencer Charlotte , Tippu Zayd , Mahadeva Ula , Green Anna , Carlyle Eleanor , Naceur-Lombardelli Cristina , consortium PEACE , Jamal-Hanjani Mariam , Swanton Charles , Turajlic Samra , Loo Peter Van 
Published: January 2023

Abstract
Background: The vast majority of cancer deaths can be attributed to tumor metastases. Disseminated tumor cells (DTCs) are thought to act as a reservoir of tumor clones which can lie dormant before causing overt metastases. Their presence has been shown to be a poor prognostic indicator in several tumor types. Despite their importance, the timing and source of DTCs is unclear across most solid cancers and even less is known about them in late-stage disease. The Posthumous Evaluation of the Advanced Cancer Environment (PEACE) post-mortem study enables extensive sampling of malignant lesions but also normal tissues, thereby allowing study of DTCs in patients with advanced cancer. Methods: We performed research autopsy sampling of macroscopically normal bone, lung and liver in 3 patients with advanced clear cell renal cell carcinoma (RCC). In addition, we performed bone marrow aspiration at autopsy from vertebral bodies and the ilium using an anterior approach. Mechanical disaggregation followed by collagenase digestion was used to generate single cell suspensions. Detection of tumor cells was carried out using antibodies against known tumor or epithelial markers carbonic anhydrase IX (CAIX). Epithelial cell adhesion molecule (EpCAM) was also used for bone marrow samples as native bone marrow cells do not express this marker. These sub-populations were then isolated using fluorescence activated cell sorting and DNA was extracted and amplified from single cells. Results: We performed and optimised collagenase-based digestion on all solid tissues collected. The percentage of viable cells generated varied significantly between subjects and tissues with bone marrow samples more viable than lung and liver. Rare and distinct populations of CAIX+ and EpCAM+ cells were detected in normal tissues between 0.5-2%. DNA amplification was successful on single cells isolated from normal lung and liver but not from bone tissue. Pilot shallow coverage whole genome sequencing revealed genomically aberrant cells ranging from single chromosome arm losses to widespread copy number aberrations. Conclusion: We demonstrate feasibility of sequencing single cells from autopsy study subjects. Rare populations of single cells with markers of clear cell RCC were detected and isolated both in normal tissues of patients with advanced disease. Genomic analyses of these cells will lead to insights into their relationship to the primary tumor and overt metastatic lesions.
Citation Format: Haixi Yan, Cristina Cotobal Martin, Christie English, Annelien Verfaillie, Jonas Demeulemeester, Andrew Rowan, Annika Fendler, Anne-Laure Cattin, Sucheta Mahapatra, Lewis Au, Scott Shepherd, Ben Shum, Charlotte Spencer, Zayd Tippu, Ula Mahadeva, Anna Green, Eleanor Carlyle, Cristina Naceur-Lombardelli, PEACE consortium, Mariam Jamal-Hanjani, Charles Swanton, Samra Turajlic, Peter Van Loo. Detection of disseminated tumor cells in advanced clear cell renal cell carcinoma through research autopsy [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr A011.