Strategies for Isolating and Propagating Circulating Tumor Cells in Men with Metastatic Prostate Cancer
Selecting a well-suited method for isolating/characterizing circulating tumor cells (CTCs) is challenging. Evaluating sensitive and specific markers for prostate cancer (PCa)-specific CTC identification and analysis is crucial. We used the CellCollector EpCAM-functionalized system (CC-EpCAM) and evaluated and developed a PCa-functionalized version (CC-PCa); we then compared CTC isolation techniques that exploit the physical and biological properties of CTCs. We established two cohorts of metastatic PCa patients (mPCa; 15 in cohort 1 and 10 in cohort 2). CTC cultivation experiments were conducted with two capturing methods (Ficoll and ScreenCell). The most sensitive detection rates and highest CTC counts were reached with the CC-PCa and ScreenCell system. Patients with ≥5 CTCs isolated with CC-EpCAM had an overall survival (OS) of 0.93 years, and patients with ≥5 CTCs isolated with CC-PCa had an OS of 1.5 years in cohort 1. Nevertheless, we observed the highest sensitivity and specificity for 24-month survival by the Ficoll with CD45 depletion and ScreenCell system with May-Grunwald Giemsa (MGG) staining. The EpCAM molecule is an essential factor related to OS for CTC isolation based on biological properties in mPCa patients. The best-suited CTC capture system is not limited to one characteristic of cells but adapted to downstream analysis.
Circulating Tumor DNA Reflects Tumor Metabolism Rather Than Tumor Burden in Chemotherapy-Naive Patients with Advanced Non–Small Cell Lung Cancer: 18F-FDG PET/CT Study
We aimed to evaluate the relationships between circulating tumor cells (CTCs) or plasma cell–free DNA (cfDNA) on one side and a comprehensive range of 18F-FDG PET/CT–derived parameters on the other side in chemotherapy-naive patients with advanced non–small cell lung cancer (NSCLC). Methods: From a group of 79 patients included in a trial evaluating the role of pretreatment circulating tumor markers as predictors of prognosis in chemotherapy-naive patients with advanced NSCLC, we recruited all those who underwent 18F-FDG PET/CT for clinical reasons at our institution before inclusion in the trial (and thus just before chemotherapy). For each patient, a peripheral blood sample was collected at baseline for the evaluation of CTCs and cfDNA. CTCs were isolated by size using a filtration-based device and then morphologically identified and enumerated; cfDNA was isolated from plasma and quantified by a quantitative polymerase chain reaction using human telomerase reverse transcriptase. The following 18F-FDG PET/CT–derived parameters were computed: maximum diameter of the primary lesion (T), of the largest lymph node (N), and of the largest metastatic lesion (M); SUVmax; SUVmean; size-incorporated SUVmax; metabolic tumor volume; and total lesion glycolysis. All parameters were independently measured for T, N, and M. The associations among CTCs, cfDNA, and 18F-FDG PET/CT–derived parameters were evaluated by multivariate-analysis. Patients were divided into 2 groups according to the presence of either limited metastatic involvement (M1a or M1b due to extrathoracic lymph nodes only) or disseminated metastatic disease. The presence or absence of metabolically active bone lesions was also recorded for each patient, and patient subgroups were compared. Results: Thirty-seven patients recruited in the trial matched our PET-based criteria (24 men; age, 64.5 ± 8.1 y). SUVmax for the largest metastatic lesion was the only variable independently associated with baseline cfDNA levels (P = 0.016). Higher levels of cfDNA were detected in the subgroup of patients with metabolically active bone lesions (P = 0.02), but no difference was highlighted when patients with more limited metastatic disease were compared with patients with disseminated metastatic disease. Conclusion: The correlation of cfDNA levels with tumor metabolism, but not with metabolic tumor volume at regional or distant levels, suggests that cfDNA may better reflect tumor biologic behavior or aggressiveness rather than tumor burden in metastatic NSCLC.