Abstract 1958: CTC surge

Abstract

Abstract Circulating Tumor Cells (CTC) are a prognostic biomarker for some types of malignant epithelial cancers and have been correlated with poor clinical outcomes. However, the routine measurement of CTC in clinical practice is still very uncommon and some key features of CTC in clinical samples are only being discovered. One of these features that we have identified by supporting CTC clinical research for over 10 years, is the presence of two distinct patient populations: one with high levels of CTC >220/7.5mL blood and one with levels of CTC <160/7.5mL. The clinical significance of this observation is still unknown, but based on this report, we propose a new oncology phenomenon: CTC Surge. Methods: In the past ten years we worked on more than half dozen clinical study projects by using CellSearch Systems by Menarini Silicon Biosystems (formerly Veridex), the only CTC technology platform approved by FDA. The Cell Search system detects CTCs by staining with surface markers coated on nanoparticle beads. The detection of CTC is linear over the reportable range of 0 to 1238 tumor cells. The FDA-approved clinical significant cut-off lines are 5 CTCs for prostate and breast cancers, and 3 for colorectal cancer. Results: All CTC results are sorted by count from low to high. There are two distinct groups roughly above 220 and below 160 per 7.5 mL of peripheral blood. The significance of a CTC enumeration > 220 is that there are as many as 150,000 tumor cells in circulation at the moment of sample collection. This may be the reason why some patients’ condition suddenly worsens when there is an overwhelming presence of CTCs in the bloodstream. The CTC test is a great tool for clinicians and scientists to monitor cancer diseases progression. Unlike a low number of CTCs that may actively engage in intravasation through a set of genes, the mechanism of CTC Surge likely has a completely different set of driving forces, such as internal wound, tumor necrosis and open access to blood vessels inside or surround the tumor mass. Although we do not yet know the clinical significance of our observation, the CTC test offers a simple tool to monitor the rapidly changing tumor dynamics seen in CTC Surge. Citation Format: Chengsen Xue, Timothy K. Amukele. CTC surge [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1958.