Currently, there is extensive information about circulating tumor cells (CTCs) and their prognostic value; however, little is known about other characteristics of these cells. In this prospective study, we assessed the gene transcripts of epithelial-to-mesenchymal transition inducing transcription factors (EMT-TFs) and cancer stem cell features in HER2+ metastatic breast cancer (MBC) patients. Epithelial cells were enriched from peripheral blood mononuclear cells (PBMCs) using antibody-coated anti-CD326 antibody (CD326+) magnetic beads, and the residual CD326− PBMCs were further depleted of leukocytes using anti-CD45 antibody-coated magnetic beads (CD326−CD45−). RNA was extracted from all cell fractions, reverse transcribed to cDNA, and subjected to quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to detect EMT-TFs (TWIST1, SNAIL1, ZEB1, and TG2) as a measure of CTCs undergoing EMT (EMT-CTCs). Additionally, PBMCs were analyzed using multi-parameter flow cytometry for ALDH activity and cancer stem cells (CSCs) that express CD24, CD44, and CD133. Twenty-eight patients were included in this study. At least one EMT-TF mRNA was elevated in the CTCs of 88.2% of patients and in the CD326−CD45− cell fraction of 60.7% of patients. The CD326−CD45− fraction of patients with elevated SNAIL1 and ZEB1 transcripts also had a higher percentage of ALDH+/CD133+ cells in their blood than did patients with normal SNAIL1 and ZEB1 expression (P=0.038). Our data indicate that HER2+ MBC patients have EMT-CTCs. Moreover, an enrichment of cancer stem cells was found in CD326−CD45− cells. Additional studies are needed to determine whether EMT-CTCs and CSCs have prognostic value in HER2+ MBC patients treated with trastuzumab-based therapy.

The metastatic cascade is a series of biological processes that enable the movement of tumor cells from the primary site to a distant location and the establishment of a new cancer growth. Circulating tumor cells (CTCs) have a crucial role in tumor dissemination. The role of CTCs in treatment failure and disease progression can be explained by their relation to biological processes, including the epithelial-to-mesenchymal transition and 'self seeding', defined as reinfiltration of the primary tumor or established metastasis by more aggressive CTCs. CTCs are a unique and heterogeneous cell population with established prognostic and predictive value in certain clinical situations. The possibility of collecting sequential blood samples for real-time monitoring of systemic-therapy efficacy presents new possibilities to evaluate targeted therapies based on the genomic profiling of CTCs and to improve the clinical management of patients by personalized therapy. Interruption of the metastatic cascade via the targeting of CTCs might be a promising therapeutic strategy.

Epithelial cancer cells are likely to undergo epithelial mesenchymal transition (EMT) prior to entering the peripheral circulation. By undergoing EMT, circulating tumor cells (CTCs) lose epithelial markers and may escape detection by conventional methods. Therefore, we conducted a pilot study to investigate mRNA transcripts of EMT-inducing transcription factors (TFs) in tumor cells from the peripheral blood (PB) of primary breast cancer (PBC) patients. Peripheral blood mononuclear cells were isolated from 52 stages I–III PBC patients and 30 healthy donors (HD) and sequentially depleted of EpCAM+ cells and CD45+ leukocytes, henceforth referred to as CD45−. The expression levels of EMT-inducing TFs (TWIST1, SNAIL1, SLUG, ZEB1, and FOXC2) in the CD45− cells were determined using qRT-PCR. The highest level of expression by the CD45− cell fraction of HD was used as “cut off” to determine if samples from PBC patients overexpressed any EMT-inducing TFs. In total, 15.4% of PBC patients overexpressed at least one of the EMT-inducing TF transcripts. Overexpression of any EMT-inducing TF transcripts was more likely to be detected in PBC patients who received neoadjuvant therapies (NAT) than patients who received no NAT (P = 0.003). Concurrently, CTCs were detected in 7 out of 38 (18.4%) patients by CellSearch® and 15 out of 42 (35.7%) patients by AdnaTest™. There was no association between the presence of CTCs measured by CellSearch® or AdnaTest™. In summary, our results demonstrate that CTCs with EMT phenotype may occur in the peripheral circulation of PBC patients and NAT is unable to eliminate CTCs undergoing EMT.

IntroductionCirculating tumor cells (CTCs) represent an independent predictor of outcome in patients with metastatic breast cancer (MBC). We assessed the prognostic impact of CTCs according to different first-line systemic treatments, and explored their potential predictive value in MBC patients.MethodsWe retrospectively evaluated 235 newly diagnosed MBC patients, treated at the University of Texas MD Anderson Cancer Center. All patients had a baseline CTC assessment performed with CellSearch®. Progression-free survival and overall survival were compared with the log-rank test between groups, according to CTC count (< 5 vs. ≥ 5) and type of systemic therapy. We further explored the predictive value of baseline CTCs in patients receiving different treatments.ResultsAt a median follow-up of 18 months, the CTC count was confirmed to be a robust prognostic marker in the overall population (median progression-free survival 12.0 and 7.0 months for patients with CTC < 5 and ≥ 5, respectively; P < 0.001). Conversely, in patients with human epidermal growth factor receptor-2-overexpressed/amplified tumors receiving trastuzumab or lapatinib, the baseline CTC count was not prognostic (median progression-free survival 14.5 months for patients with CTC < 5 and 16.1 months for those with CTC ≥ 5; P = 0.947). Furthermore, in patients with human epidermal growth factor receptor-2 normal tumors, a baseline CTC count ≥ 5 identified subjects who derived benefit from more aggressive treatments, including combination chemotherapy and chemotherapy plus bevacizumab.ConclusionsThis analysis suggests that the prognostic information provided by CTC count may be useful in patient stratifications and therapeutic selection, particularly in the group with positive CTCs, in which various therapeutic choices may procure differential palliative benefit.

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In this translational study, we showed, for the first time, the prognostic value of PD-L1 expression in TGCTs and our data imply that the PD-1/PD-L1 pathway could be a novel therapeutic target in TGCTs.

IntroductionTraditional factors currently used for prognostic stratification do not always adequately predict treatment response and disease evolution in advanced breast cancer patients. Therefore, the use of blood-based markers, such as circulating tumor cells (CTCs), represents a promising complementary strategy for disease monitoring. In this retrospective study, we explored the role of CTC counts as predictors of disease evolution in breast cancer patients with limited metastatic dissemination.MethodsA total of 492 advanced breast cancer patients who had a CTC count assessed by CellSearch prior to starting a new line of systemic therapy were eligible for this analysis. Using the threshold of 5 CTCs/7.5 ml of blood, pretreatment CTC counts were correlated in the overall population with metastatic site distribution, evaluated at baseline and at the time of treatment failure, using Fisher’s exact test. Time to visceral progression and time to the development of new metastatic lesions and sites were estimated in patients with nonvisceral metastases and with single-site metastatic disease, respectively, by the Kaplan-Meier method. Survival times were compared between groups according to pretreatment CTC count by logrank test.ResultsIn the overall population, a pretreatment level ≥5 CTCs/7.5 ml was associated with an increased baseline number of metastatic sites compared with <5 CTCs/7.5 ml (P = 0.0077). At the time of treatment failure, patients with ≥5 CTCs/7.5 ml more frequently developed new metastatic lesions and sites compared with those with <5 CTCs/7.5 ml (development of new lesions: P = 0.0002; development of new sites: P = 0.0031). Among patients with disease originally confined to nonvisceral sites, ≥5 CTCs/7.5 ml was associated with remarkably shorter time to visceral metastases (P = 0.0021) and overall survival (P = 0.0006) compared with <5 CTCs/7.5 ml. In patients with single-site metastatic disease, ≥5 CTCs/7.5 ml was associated with a significant reduction of the time to development of new metastatic sites (P = 0.0051) and new lesions (P = 0.0002) and with worse overall survival (P = 0.0101).ConclusionOur results suggest that baseline CTC counts can be used as an early predictor of metastatic potential in breast cancer patients with limited metastatic dissemination.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-014-0440-8) contains supplementary material, which is available to authorized users.

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