Improved Circulating Tumor Cell Detection by a Combined EpCAM and MCAM CellSearch Enrichment Approach in Patients with Breast Cancer Undergoing Neoadjuvant Chemotherapy

Abstract

Circulating tumor cells (CTC) are detected by the CellSearch System in 20% to 25% of patients with primary breast cancer (pBC). To improve CTC detection, we investigated melanoma cell adhesion molecule (MCAM) as enrichment marker next to epithelial cell adhesion molecule (EpCAM) and tested the clinical relevance of MCAM-positive CTCs in patients with HER2-negative stage II/III pBC starting neoadjuvant chemotherapy (NAC) in the NEOZOTAC trial. Using the CellSearch System, EpCAM-positive and MCAM-positive CTCs were separately enriched from 7.5 mL blood, at baseline and after the first NAC cycle. Circulating endothelial cells (CEC) were measured using flow cytometry. Primary objective was to improve the CTC detection rate to !40% combining EpCAM/MCAM. Correlations of CTC and CEC counts and pathologic complete response (pCR) were also explored. At baseline, we detected EpCAM-positive and MCAM-positive CTCs in 12 of 68 (18%) and 8 of 68 (12%) patients, respectively. After one cycle, this was 7 of 44 (16%) and 7 of 44 (16%) patients, respectively. The detection rate improved from 18% at baseline and 16% after one cycle with EpCAM to 25% (P ¼ 0.08) and 30% (P ¼ 0.02), respectively, with EpCAM/ MCAM. No patients with MCAM-positive CTCs versus 23% of patients without MCAM-positive CTCs at baseline achieved pCR (P ¼ 0.13). EpCAM-positive CTCs and CEC counts were not correlated to pCR. Combined EpCAM/MCAM CellSearch enrichment thus increased the CTC detection rate in stage II/III pBC. We found no associations of CTC and CEC counts with pCR to NAC. The clinical relevance of MCAM-positive CTCs deserves further study.

Single Cell Transcriptome in Colorectal Cancer—Current Updates on Its Application in Metastasis, Chemoresistance and the Roles of Circulating Tumor Cells

“…Characterization of these cells verified the presence of multipotent cells responsible for genetic and phenotypic heterogeneity, endowing them with strong metastatic potential. In addition, six genes (AGR2, CEACAM5, CLDN3, KRT18, EpCAM and FGFR3) were detected as differentially expressed in the generated CTC cell lines, which was similar to primary CRC cells grown under similar conditions (Smirnov et al, 2005;Mostert et al, 2015;Onstenk et al, 2015). The CTC lines also displayed enhanced drug/xenobiotics metabolizing activity, in particular via cytochrome P450 pathway, suggesting resistance to conventional therapies.…”

Circulating tumor cells in breast cancer

“…The impact of EMT-associated EpCAM downregulation on CTC detection by EpCAM-dependent techniques, such as the CellSearch Ò system, has been repeatedly reported. Although most of BC subtypes can be efficiently captured by EpCAMbased assays (Ring et al, 2015), several EMT-related antigens have been successfully investigated in addition to EpCAMbased immunoselection as an effective way to increase CTC detection (Mostert et al, 2012Onstenk et al, 2015a;Satelli et al, 2015).…”

Circulating Tumor Cell Subtypes may Predict Responses to Neoadjuvant Chemotherapy in Locally Advanced Breast Cancer

“…However, the predictive value of CTCs for NCT response remains controversial. CTC detection clinical trials based on the CellSearch® system suggested EpCAM-positive CTC counts were not correlated to pCR in NCT [21,22]. Our previous study demonstrated that systemic adjuvant chemotherapy had a significant impact on CTCs, as assessed via RT-PCR, and this effect was observed after three cycles of chemotherapy [7].…”