Clinical implications of the detection of circulating tumor cells in breast cancer patients

Quantification of circulating tumour cells over time in dogs with appendicular osteosarcoma

Enumeration of circulating tumour cells (CTC) has shown promise for prognostication and guidance of therapeutic decisions in human cancers. The objective of this study was to enumerate CTC over time in dogs with naturally occurring osteosarcoma (OSA), and to determine correlation with patient outcome. Twenty-six dogs with OSA and no evidence of metastatic disease at the time of amputation were enrolled. Dogs were assessed for lung metastases and CTC prior to and following amputation, and at each chemotherapy visit. Twenty-one dogs completed the study. Nineteen dogs were euthanized and two were alive and free of metastases. Overall survival time ranged from 88 to 1058 days (median survival time (MST) 374 days). Increased serum alkaline phosphatase activity, advanced age, and higher body weight were significantly associated with lower MST. Dogs with OSA had a mean of 356 (0 to 4443) CTC/106 leukocytes. In 12 of 15 dogs that developed radiographic evidence of metastasis, a pre-metastatic CTC spike was retrospectively detectable on average 36.5 (1-100 days) days prior to metastasis and was associated with significantly shorter MST (301 ± 64 vs. 626 ± 55 days; p = .0107). In a multivariable analysis, dogs with a CTC spike were 10× more likely to die compared with those without. These results suggest that a spike in CTC frequency precedes detection of metastasis in dogs with OSA and is associated with shorter survival. More frequent enumeration of CTC in a larger cohort of dogs with OSA may be warranted.

Circulating Tumor Cells in Breast Cancer

With active screening for early detection and advancements in treatment, there has been a significant decrease in mortality from breast cancer. However, a significant proportion of patients with non-metastatic breast cancer at time of diagnosis will relapse. Therefore, it is suggested that the dissemination of bloodstream tumor cells (circulating tumor cells, CTCs) undetectable by currently available diagnostic tools occurs during the early stages of breast cancer progression, and may be the potential source of micrometastases responsible for treatment failures. Here, we review the clinical significance of CTCs, as detected by the FDA-approved CellSearch^® System, in both metastatic and non-metastatic breast cancer patients. Studies so far suggest that CTCs are prognostic of poorer outcomes in breast cancer patients; however, there is currently insufficient data to support use of CTC data to guide treatment. Therefore, there are ongoing studies to evaluate the utility of assessing CTC phenotypes to develop personalized breast cancer treatment, which will be reviewed in this chapter.

Exosomes from differentially activated macrophages influence dormancy or resurgence of breast cancer cells within bone marrow stroma

Breast cancer (BC) cells (BCCs) can retain cellular quiescence for decades, a phenomenon referred to as dormancy. BCCs show preference for the bone marrow (BM) where they can remain dormant for decades. Targeting BCCs within the BM is a challenge since the dormant BCCs reside within BM stroma, also residence for hematopoietic stem cells (HSCs). Dormant BCCs could behave as cancer stem cells (CSCs). The CSCs and HSCs are similar by function and also, by commonly expressed genes. The method by which dormant BCCs transition into clinically metastatic cells remains unclear. This study tested the hypothesis that macrophages (MΦs) within BM stroma, facilitates dormancy or reverse this state into metastatic cells. MΦs exhibiting an M2 phenotype constitute ~10% of cultured BM stroma. The M2 MΦs form gap junctional intercellular communication (GJIC) with CSCs, resulting in cycling quiescence, reduced proliferation and carboplatin resistance. In contrast, MΦs expressing the M1 phenotype reversed BC dormancy. Activation of M2a MΦs via the toll-like receptor 4 (TLR4) switched to M1 phenotype. The switch can occur by direct activation of M2a MΦs, or indirectly through activation of mesenchymal stem cells. M1 MΦ-derived exosomes activated NFкB to reverse quiescent BCCs to cycling cells. Using an in vivo model of BC dormancy, injected Mi MOs sensitized BCCs to carboplatin and increased host survival. In summary, we have shown how BM stromal MΦs, through exosomes, regulate the behavior of BCCs, by either inducing or reversing dormancy.

The impact of HER2 phenotype of circulating tumor cells in metastatic breast cancer: a retrospective study in 107 patients

BACKGROUND

In metastatic breast cancer (MBC), antigen profiles of metastatic tissue and primary tumor differ in up to 20 % of patients. Reassessment of predictive markers, including human epidermal growth factor receptor 2 (HER2) expression, might help to optimize MBC treatment. While tissue sampling is invasive and often difficult to repeat, circulating tumor cell (CTC) analysis requires only a blood sample and might provide an easy-to-repeat, real-time "liquid biopsy" approach. The present retrospective study was conducted to compare HER2 expression in primary tumors, metastatic tissue, and circulating tumor cells (CTCs) from MBC patients and to analyze the potential impact of HER2 overexpression by CTCs on progression-free (PFS) and overall survival (OS) in MBC.

METHODS

CTC-positive (five or more CTCs/7.5 mL blood; CellSearch®, Janssen Diagnostics) MBC patients starting a new line of systemic treatment were eligible for the study. HER2 status of CTCs was determined by immunofluorescence (CellSearch®). HER2 status of primary (PRIM) and metastatic (MET) tumor tissue was determined by immunohistochemistry. Data were analyzed using descriptive statistics and Kaplan-Meier plots.

RESULTS

One hundred seven patients (median age (range) 57 (33-81) years) were included. 100/107 (93%) patients were followed-up for a median [95% confidence interval (CI)] of 28.5 [25.1-40.1] months. Of 37/107 (35%) CTC-HER2-positive patients only 10 (27%) were PRIM-HER2-positive. 6/46 (13%) patients were MET-HER2-positive; only 2/10 (20%) CTC-HER2-positive patients were MET-HER2-positive. Overall accuracy between CTC-HER2 expression and PRIM-HER2 and MET-HER2 status was 69% and 74%, respectively. Kaplan-Meier plots of PFS and OS by CTC-HER2 status revealed significantly longer median [95% CI] PFS of CTC-HER2-positive versus CTC-HER2-negative patients (7.4 [4.7-13.7] versus 4.34 [3.5-5.9] months; p = 0.035). CTC-HER2-positive status showed no significant difference for OS (13.7 [7.7-30.0] versus 8.7 [5.9-15.3] months; p = 0.287).

CONCLUSIONS

HER2 status can change during the course of breast cancer. CTC phenotyping may serve as an easy-to-perform "liquid biopsy" to reevaluate HER2 status and potentially guide treatment decisions. Further, prospective studies are needed.

The impact of HER2 phenotype of circulating tumor cells in metastatic breast cancer: a retrospective study in 107 patients

Background

In metastatic breast cancer (MBC), antigen profiles of metastatic tissue and primary tumor differ in up to 20 % of patients. Reassessment of predictive markers, including human epidermal growth factor receptor 2 (HER2) expression, might help to optimize MBC treatment. While tissue sampling is invasive and often difficult to repeat, circulating tumor cell (CTC) analysis requires only a blood sample and might provide an easy-to-repeat, real-time “liquid biopsy” approach. The present retrospective study was conducted to compare HER2 expression in primary tumors, metastatic tissue, and circulating tumor cells (CTCs) from MBC patients and to analyze the potential impact of HER2 overexpression by CTCs on progression-free (PFS) and overall survival (OS) in MBC.

Methods

CTC-positive (five or more CTCs/7.5 mL blood; CellSearch®, Janssen Diagnostics) MBC patients starting a new line of systemic treatment were eligible for the study. HER2 status of CTCs was determined by immunofluorescence (CellSearch®). HER2 status of primary (PRIM) and metastatic (MET) tumor tissue was determined by immunohistochemistry. Data were analyzed using descriptive statistics and Kaplan–Meier plots.

Results

One hundred seven patients (median age (range) 57 (33–81) years) were included. 100/107 (93 %) patients were followed-up for a median [95 % confidence interval (CI)] of 28.5 [25.1–40.1] months. Of 37/107 (35 %) CTC-HER2-positive patients only 10 (27 %) were PRIM-HER2-positive. 6/46 (13 %) patients were MET-HER2-positive; only 2/10 (20 %) CTC-HER2-positive patients were MET-HER2-positive. Overall accuracy between CTC-HER2 expression and PRIM-HER2 and MET-HER2 status was 69 % and 74 %, respectively. Kaplan–Meier plots of PFS and OS by CTC-HER2 status revealed significantly longer median [95 % CI] PFS of CTC-HER2-positive versus CTC-HER2-negative patients (7.4 [4.7–13.7] versus 4.34 [3.5–5.9] months; p = 0.035). CTC-HER2-positive status showed no significant difference for OS (13.7 [7.7–30.0] versus 8.7 [5.9–15.3] months; p = 0.287).

Conclusions

HER2 status can change during the course of breast cancer. CTC phenotyping may serve as an easy-to-perform “liquid biopsy” to reevaluate HER2 status and potentially guide treatment decisions. Further, prospective studies are needed.

Hierarchy of breast cancer cells: key to reverse dormancy for therapeutic intervention

An understanding of how cancer cells adapt dormancy would allow for targeted treatment. The current literature suggests that the cancer stem cells might be the major cells with the ability to become quiescent and to resist current drug treatment. The properties of cancer stem cells and healthy stem cells are functionally similar, thereby posing a challenge to target the dormant cells. The bone marrow is particularly a challenge because the dormant breast cancer cells are close to the endosteum, which is also home to the endogenous hematopoietic stem cells. Here we discuss how research studies could bring an understanding of the cellular and molecular interactions between the cancer stem cells and cells within the bone marrow microenvironment. This will allow for intervention to reverse dormancy for targeted treatment. The treatment will require studies within the normal organ functions to ensure treatment without toxicity.

The HER2 status of disseminated tumor cells in the bone marrow of early breast cancer patients is independent from primary tumor and predicts higher risk of relapse

Overexpression of the HER2-receptor in early breast cancer (EBC) patients is associated with aggressive tumor behavior. However, women suffering from HER2-positive EBC benefit from trastuzumab treatment. As the HER2 status of the primary tumor may differ from that of disseminated tumor cells (DTC) in bone marrow (BM), the aim of this study was (1) to compare the HER2 status of the primary tumor (prim-HER2-status) with that of DTC (DTC-HER2-status) and (2) to analyze the influence of the DTC-HER2-status on patient survival. For this purpose, BM aspirates from 569 EBC patients were analyzed for the presence of DTC. The DTC-HER2-status was identified by a double-staining procedure against cytokeratin and the HER2-receptor. DTC were detected in 151 (27 %) patients. The concordance between the HER2 status of DTC and the primary tumor was 51 %. In patients with detectable DTC, mean disease-free survival was 77.44 (95 % CI 74.72-80.17) months for DTC-HER2-negative and 55.15 (95 % CI 48.57-61.79) months for DTC-HER2-positive patients (p = 0.044). The multivariate analysis showed that the DTC-HER2-status was an independent predictor of disease-free survival. In conclusion, the presence of HER2-positive DTC in EBC patients is associated with an increased risk of relapse. Due to the low concordance between the HER2 status of the primary tumor and DTC, only a minority (13 %) of the DTC-HER2-positive patients was treated with trastuzumab. These patients might, however, benefit from HER2-directed therapy.

The presence and prognostic impact of apoptotic and nonapoptotic disseminated tumor cells in the bone marrow of primary breast cancer patients after neoadjuvant chemotherapy

INTRODUCTION

Neoadjuvant systemic therapy of primary breast cancer (PBC) patients offers the possibility to monitor treatment response. However, patients might have metastatic relapse despite achieving a pathologic complete response (pCR). This indicates that local response to therapy must not be representative for systemic treatment efficacy. Therefore, the aim of this study was to compare local response with systemic tumor cell dissemination by determining the presence of disseminated tumor cells (DTCs), including apoptotic tumor cells, in the bone marrow (BM) of PBC patients after neoadjuvant chemotherapy (NACT).

METHODS

DTCs were detected by immunocytochemistry (pancytokeratin antibody A45-B/B3) and cytomorphology (DTC status). The presence of apoptotic tumor cells was determined by using the M30 antibody (M30 status). This antibody detects a neo-epitope that is expressed only during early apoptosis.

RESULTS

BM aspirates from 400 PBC patients that had completed NACT were eligible for this study. Of these, 167 (42%) patients were DTC positive (DTC status). The M30 status was investigated in 308 patients. Apoptotic (M30-positive) tumor cells were detected in 89 (29%) of these. Whereas the DTC status was not correlated (P = 0.557) to local treatment response (that is, pCR or a clinical complete/partial response), the presence of M30-positive tumor cells was significantly higher in patients that responded to therapy (P = 0.026). Additionally, DTC-positive patients were at an increased risk for disease relapse (hazard ratio, 1.87; 95% CI, 1.11 to 3.15; P = 0.019).

CONCLUSION

The presence of DTC is independent of therapy response of the primary tumor. As patients that are DTC positive after NACT have an unfavorable outcome, they might benefit from additional systemic treatment.

Emerging insights into head and neck cancer metastasis

The purpose of this review was to provide biological concepts of head and neck cancer metastasis. To attain this goal, we analyzed peer-reviewed articles related to head and neck cancer metastasis obtained though PubMed and archived articles. Articles related to the biologic principles of head and neck cancer metastasis were reviewed and summarized. As locoregional control has improved for patients with head and neck cancer, rates of distant metastasis have not decreased. As patients live longer, many will die of complications related to the development of disease at sites below the clavicles. Emerging evidence now suggests a more complicated framework of metastatic behavior for head and neck cancer. Here, we review the role of regional lymph nodes in containing advanced head and neck cancer, evidence for active as opposed to passive tumor cell metastasis, and clinical implications these concepts have on both treatment of head and neck cancer and future research.