Abstract 585: A robust method for expanding patient-derived circulating tumor cells ex vivo

Abstract

Abstract In the United States, an estimated 280,000 people will be diagnosed with invasive breast cancer, which has a 5-year survival rate of 27% and 22% in females and males, respectively. Despite the clinical burden of metastasis, the underlying machinery of metastasis remains unclear. This is largely due to a lack of available technologies that can robustly expand patient-derived metastatic cell populations for study ex vivo. One such population is circulating tumor cells (CTCs), which are cells that escape from the primary tumor, intravasate through blood vessel endothelium, and circulate throughout the body. Eventually, CTCs will extravasate at the metastatic site and become the seeds for metastatic colonization. Based on their role in metastasis, CTCs yield great promise for identifying key mechanistic drivers of metastasis. Unfortunately, CTCs exist in low levels within the blood (typically < 100 cells/10mL of blood). Previous methods for culturing CTCs ex vivo have reported low success rates (~ 20%), and often depend on the presence of a high number of CTCs for success. To better interrogate the mechanisms of metastasis, robust methods to propagate CTCs for study are needed. Recently, our lab developed a method using an unbiased selection criterion for isolating and propagating CTCs derived from metastatic breast cancer, yielding 100% success in twelve distinct individuals. This method, based on a density gradient centrifugation, extracts not only CTCs from blood plasma, but also includes potential cancer-associated neutrophils and macrophages. All cultures under our conditions demonstrated growth for > 30 days and were confirmed to have an epithelial and breast phenotype. Notably, 6/12 samples grew longer and were associated with increased CD45 expression using qRT-PCR. We have also recently demonstrated further success in culturing CTCs derived from a variety of other cancers, including colorectal, lung, and pancreatic cancers. This study therefore not only defines a novel technology for expanding CTCs, but also suggests a deficiency in modern isolation methods, which rely on CD45 exclusion, that is limiting culture success in previous methods. Citation Format: Jerry Xiao, Joshua D. Kassner, Kelly Stanton, Richard Schlegel, Paula R. Pohlmann, Seema Agarwal. A robust method for expanding patient-derived circulating tumor cells ex vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 585.