Mark P. Ward

Circulating tumour cells are a prognostic indicator in advanced high-grade serous ovarian cancer and are associated with platelets and immune cells following dissemination

Abstract Background Circulating tumour cells (CTCs) are rare yet crucial biomarkers with significant prognostic potential across different cancer types. However, their role in high-grade serous ovarian cancer (HSGC) is not well defined. To capture the full spectrum of CTCs found in HGSC, we employed an EpCAM independent enrichment technique in patients with advanced HGSC and investigated the prognostic value and molecular signatures of these rare cells. Methods CTC enumeration was performed in 43 newly diagnosed patients with HGSC using Parsortix® CTC enrichment and benchmarked against a metastatic breast cancer (MBC) cohort for which the device is FDA approved. CTCs were also isolated from the ovarian vein of patients with HGSC during primary cytoreductive surgery. CTCs were assessed as prognostic markers in patients with HGSC. FACS single cell sorting and scRNAseq was performed on CTCs isolated from the ovarian vein. Results CTCs isolated using Parsortix® enrichment in HGSC ranged between 1-22 cells/7.5 ml blood. Concordance was seen between Parsortix® enrichment and CellSearch® enumeration in patients with MBC (R 2  = 0.8786). CTC clusters were isolated from the ovarian vein ( P  = 0.0195) and were cloaked in platelets/immune cells. Detection of CTCs in patients with HGSC was predictive of a poorer progression free survival ( P  = 0.0183). Patients with CTCs were found to have increased serum levels of CD73 ( P  = 0.0311). scRNAseq of CTCs isolated from the ovarian vein identified enrichment in genes associated with immune signalling. Conclusions Peripheral CTCs isolated from patients with HGSC were predictors of a poor prognosis. The ovarian vein was found to be a rich source of disseminating CTC clusters in HGSC. Further studies are warranted to investigate the utility of CTCs as markers of neoadjuvant chemotherapy response as well as for longitudinal monitoring. Molecular analysis of CTCs in HGSCs reveals a potential role of the immune system in CTC-mediated haematogenous metastasis.

A pilot study evaluating the feasibility of enriching and detecting circulating tumour cells from peripheral and ovarian veins in rare epithelial ovarian carcinomas.

Studies on circulating tumour cells (CTCs) in rare epithelial ovarian carcinomas (EOC) are limited, despite their potential as a minimally invasive biomarker for monitoring cancer progression and predicting outcomes. This pilot study aimed to assess the feasibility of enriching and detecting CTCs from both peripheral and ovarian vein blood samples in rare EOC subtypes. Blood samples were collected from the peripheral and ovarian veins of 20 patients with rare EOC. Among the 20 patients, 12 had early-stage disease (I-II), while 8 had advanced disease (III-IV). CTCs were enriched using the Parsortix® system and immunophenotyped via immunofluorescence targeting epithelial markers (EpCAM/pan-cytokeratin) and Hoechst for positive selection, and CD45 for negative selection. CTC status (positive versus negative) was correlated with clinicopathological data. CTCs were successfully detected in 45 % (1-19 CTCs) of baseline peripheral samples and 55 % (1-4776 CTCs) of ovarian vein samples. CTC doublets and clusters were detected in ovarian vein samples (3/11), but not in peripheral samples (0/20). A higher proportion of deaths were observed in CTC+ patients compared to CTC- patients (p = 0.0088). Here we demonstrate the feasibility of enriching and detecting CTCs from both peripheral and ovarian vein blood in patients with rare EOC. The higher CTC yield in ovarian vein blood suggests that tumour-draining blood may play a role in improving CTC detection. This pilot study paves the way for larger studies to investigate the prognostic utility of CTCs and refine their clinical value in these rare understudied EOC.

Unravelling the biological and clinical challenges of circulating tumour cells in epithelial ovarian carcinoma

Epithelial ovarian carcinoma (EOC) is the eighth most common cancer in women and the leading cause of gynaecological cancer death, predominantly due to the absence of effective screening tools, advanced stage at diagnosis, and high rates of recurrence. Circulating tumour cells (CTCs), a rare subset of tumour cells that disseminate from a tumour and migrate into the circulation, play a pivotal role in the metastatic cascade, and therefore hold promise as biomarkers for disease monitoring and prognostication. Exploring CTCs from liquid biopsies is an appealing approach for research and clinical practice, given it is minimally invasive, facilitates serial sampling and enables the capture of the entire spectrum of cancer cells circulating in the blood. The prognostic utility of CTC enumeration has been FDA-approved for clinical use in metastatic breast, prostate, and colorectal cancers. However, the unique biology of EOC, discussed herein, compounds the detection and characterisation complexities already inherent in CTC research, consequently hindering progress towards clinical applications. The aim of this review is to provide an overview of both the biological and clinical challenges encountered in harnessing the power of CTCs in EOC.