Longitudinal Dynamics of Circulating Tumor Cells and Circulating Tumor DNA for Treatment Monitoring in Metastatic Breast Cancer.

Liquid biopsy-based biomarkers, including circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), are increasingly important for the characterization of metastatic breast cancer (MBC). The aim of the study was to explore CTCs and ctDNA dynamics to better understand their potentially complementary role in describing MBC. METHODS: The study retrospectively analyzed 107 patients with MBC characterized with paired CTCs and ctDNA assessments and a second prospective cohort, which enrolled 48 patients with MBC. CTCs were immunomagnetically isolated and ctDNA was quantified and then characterized through next-generation sequencing in the retrospective cohort and droplet digital polymerase chain reaction in the prospective cohort. Matched pairs variations at baseline, at evaluation one (EV1), and at progression were tested through the Wilcoxon test. The prognostic role of ctDNA parameters was also investigated. RESULTS: Mutant allele frequency (MAF) had a significant decrease between baseline and EV1 and a significant increase between EV1 and progression. Number of detected alterations steadily increased across timepoints, CTCs enumeration (nCTCs) significantly increased only between EV1 and progression. MAF dynamics across the main altered genes was then investigated. Plasma DNA yield did not vary across timepoints both in the retrospective cohort and in the prospective cohort, while the short fragments fraction showed a potential role as a prognostic biomarker. CONCLUSION: nCTCs and ctDNA provide complementary information about prognosis and treatment benefit. Although nCTCs appeared to assess tumor biology rather than tumor burden, MAF may be a promising biomarker for the dynamic assessment of treatment response and resistance.

Junctional Adhesion Molecules in Cancer: A Paradigm for the Diverse Functions of Cell-Cell Interactions in Tumor Progression.

Tight junction (TJ) proteins are essential for mediating interactions between adjacent cells and coordinating cellular and organ responses. Initial investigations into TJ proteins and junctional adhesion molecules (JAM) in cancer suggested a tumor-suppressive role where decreased expression led to increased metastasis. However, recent studies of the JAM family members JAM-A and JAM-C have expanded the roles of these proteins to include protumorigenic functions, including inhibition of apoptosis and promotion of proliferation, cancer stem cell biology, and epithelial-to-mesenchymal transition. JAM function by interacting with other proteins through three distinct molecular mechanisms: direct cell-cell interaction on adjacent cells, stabilization of adjacent cell surface receptors on the same cell, and interactions between JAM and cell surface receptors expressed on adjacent cells. Collectively, these diverse interactions contribute to both the pro- and antitumorigenic functions of JAM. In this review, we discuss these context-dependent functions of JAM in a variety of cancers and highlight key areas that remain poorly understood, including their potentially diverse intracellular signaling networks, their roles in the tumor microenvironment, and the consequences of posttranslational modifications on their function. These studies have implications in furthering our understanding of JAM in cancer and provide a paradigm for exploring additional roles of TJ proteins.

Prognostic value of HER2 status on circulating tumor cells in advanced-stage breast cancer patients with HER2-negative tumors.

PURPOSE: Discordance between HER2 expression in tumor tissue (tHER2) and HER2 status on circulating tumor cells (cHER2) has been reported. It remains largely underexplored whether patients with tHER2-/cHER2+ can benefit from anti-HER2 targeted therapies. METHODS: cHER2 status was determined in 105 advanced-stage patients with tHER2- breast tumors. Association between cHER2 status and progression-free survival (PFS) was analyzed by univariate and multivariate Cox models and survival differences were compared by Kaplan-Meier method. RESULTS: Compared to the patients with low-risk cHER2 (cHER2+ < 2), those with high-risk cHER2 (cHER2+ ≥ 2) had shorter survival time and an increased risk for disease progression (hazard ratio [HR] 2.16, 95% confidence interval [CI] 1.20-3.88, P = 0.010). Among the patients with high-risk cHER2, those who received anti-HER2 targeted therapies had improved PFS compared with those who did not (HR 0.30, 95% CI 0.10-0.92, P = 0.035). In comparison, anti-HER2 targeted therapy did not affect PFS among those with low-risk cHER2 (HR 0.70, 95% CI 0.36-1.38, P = 0.306). Similar results were obtained after adjusting covariates. A longitudinal analysis of 67 patients with cHER2 detected during follow-ups found that those whose cHER2 status changed from high-risk at baseline to low-risk at first follow-up exhibited a significantly improved survival compared to those whose cHER2 remained high-risk (median PFS: 11.7 weeks vs. 2.0 weeks, log-rank P = 0.001). CONCLUSION: In advanced-stage breast cancer patients with tHER2- tumors, cHER2 status has the potential to guide the use of anti-HER2 targeted therapy in patients with high-risk cHER2.

Association of clinical outcomes in metastatic breast cancer patients with circulating tumour cell and circulating cell-free DNA.

BACKGROUND: Both circulating tumour cell (CTC) and total circulating cell-free DNA (ccfDNA) predict cancer patient prognosis. However, no study has explored the prognostic value of the combined use of CTC and ccfDNA. We aimed to investigate individual and joint effects of CTC and ccfDNA on clinical outcomes of metastatic breast cancer (MBC) patients. METHODS: We collected 227 blood samples from 117 MBC patients. CTCs were enumerated using the CellSearch System. ccfDNAs were quantified by quantitative real-time polymerase chain reaction and Qubit fluorometer. The individual and joint effects of CTC and ccfDNA levels on patient progression-free survival (PFS) and overall survival (OS) were analysed using Cox proportional hazards models. RESULTS: Compared to patients with <5 CTCs, patients with ≥5 CTCs had a 2.58-fold increased risk of progression and 3.63-fold increased risk of death. High level of ccfDNA was associated with a 2.05-fold increased risk of progression and 3.56-fold increased risk of death. These associations remained significant after adjusting for other important clinical covariates and CTC/ccfDNA levels. CTC and ccfDNA levels had a joint effect on patient outcomes. Compared to patients with low levels of both CTC and ccfDNA, those with high levels of both markers exhibited a >17-fold increased death risk (P < 0.001). Moreover, longitudinal analysis of 132 samples from 22 patients suggested that the inconsistency between CTC level and outcome in some patients could possibly be explained by ccfDNA level. CONCLUSIONS: CTC and total ccfDNA levels were individually and jointly associated with PFS and OS in MBC patients.

CCR5 Governs DNA Damage Repair and Breast Cancer Stem Cell Expansion.

The functional significance of the chemokine receptor CCR5 in human breast cancer epithelial cells is poorly understood. Here, we report that CCR5 expression in human breast cancer correlates with poor outcome. CCR5+ breast cancer epithelial cells formed mammospheres and initiated tumors with >60-fold greater efficiency in mice. Reintroduction of CCR5 expression into CCR5-negative breast cancer cells promoted tumor metastases and induced DNA repair gene expression and activity. CCR5 antagonists Maraviroc and Vicriviroc dramatically enhanced cell killing mediated by DNA-damaging chemotherapeutic agents. Single-cell analysis revealed CCR5 governs PI3K/Akt, ribosomal biogenesis, and cell survival signaling. As CCR5 augments DNA repair and is reexpressed selectively on cancerous, but not normal breast epithelial cells, CCR5 inhibitors may enhance the tumor-specific activities of DNA damage response-based treatments, allowing a dose reduction of standard chemotherapy and radiation.Significance: This study offers a preclinical rationale to reposition CCR5 inhibitors to improve the treatment of breast cancer, based on their ability to enhance the tumor-specific activities of DNA-damaging chemotherapies administered in that disease. Cancer Res; 78(7); 1657-71. ©2018 AACR.

Cell-Free DNA and Circulating Tumor Cells: Comprehensive Liquid Biopsy Analysis in Advanced Breast Cancer.

Purpose: Liquid biopsy provides a real-time assessment of metastatic breast cancer (MBC). We evaluated the utility of combining circulating tumor cells (CTC) and circulating tumor DNA (ctDNA) to predict prognosis in MBC.Experimental Design: We conducted a retrospective study of 91 patients with locally advanced breast cancer and MBC. CTCs were enumerated by CellSearch; the plasma-based assay was performed utilizing Guardant360 and the survival analysis using Kaplan-Meier curves.Results: Eighty-four patients had stage IV cancer, and 7 patients had no metastases. Eighty patients had CTC analysis: median number 2 (0-5,612). Blood samples [232 of 277 (84%)] had mutations. The average ctDNA fraction was 4.5% (0-88.2%) and number of alterations 3 (0-27); the most commonly mutated genes were TP53 (52%), PIK3CA (40%), and ERBB2 (20%). At the time of analysis, 36 patients (39.6%) were dead. The median follow-up for CTCs was 9 months; for ctDNA, it was 9.9 months. For CTCs and ctDNA, respectively, progression-free survival (PFS) was 4.2 and 5.2 months and overall survival (OS) was 18.7 and 21.5 months. There was a statistically significant difference in PFS and OS for baseline CTCs < 5 versus CTCs ≥ 5 (P = 0.021 and P = 0.0004, respectively); %ctDNA < 0.5 versus ≥ 0.5 (P = 0.003 and P = 0.012); number of alterations < 2 versus ≥ 2 (P = 0.059 borderline and P = 0.0015). A significant association by Fisher exact test was found between the number of alterations and the %ctDNA in the baseline sample (P < 0.0001).Conclusions: The study demonstrated that liquid biopsy is an effective prognostic tool. Clin Cancer Res; 24(3); 560-8. ©2017 AACR.

Detection of Activating Estrogen Receptor Gene (ESR1) Mutations in Single Circulating Tumor Cells.

Purpose: Early detection is essential for treatment plans before onset of metastatic disease. Our purpose was to demonstrate feasibility to detect and monitor estrogen receptor 1 (ESR1) gene mutations at the single circulating tumor cell (CTC) level in metastatic breast cancer (MBC).Experimental Design: We used a CTC molecular characterization approach to investigate heterogeneity of 14 hotspot mutations in ESR1 and their correlation with endocrine resistance. Combining the CellSearch and DEPArray technologies allowed recovery of 71 single CTCs and 12 WBC from 3 ER-positive MBC patients. Forty CTCs and 12 WBC were subjected to whole genome amplification by MALBAC and Sanger sequencing.Results: Among 3 selected patients, 2 had an ESR1 mutation (Y537). One showed two different ESR1 variants in a single CTC and another showed loss of heterozygosity. All mutations were detected in matched cell-free DNA (cfDNA). Furthermore, one had 2 serial blood samples analyzed and showed changes in both cfDNA and CTCs with emergence of mutations in ESR1 (Y537S and T570I), which has not been reported previously.Conclusions: CTCs are easily accessible biomarkers to monitor and better personalize management of patients with previously demonstrated ER-MBC who are progressing on endocrine therapy. We showed that single CTC analysis can yield important information on clonal heterogeneity and can be a source of discovery of novel and potential driver mutations. Finally, we also validate a workflow for liquid biopsy that will facilitate early detection of ESR1 mutations, the emergence of endocrine resistance and the choice of further target therapy. Clin Cancer Res; 23(20); 6086-93. ©2017 AACR.

Prognostic values of cancer associated macrophage-like cells (CAML) enumeration in metastatic breast cancer.

PURPOSE: Circulating cancer associated macrophage-like cells (CAMLs) have been detected in the peripheral blood of patients with solid tumors including breast cancer. However, the prognostic relevance of CAMLs in metastatic breast cancer (MBC) has not been evaluated. In the present study, we aimed to measure CAMLs and circulating tumor cells (CTCs) at baseline and examine their prognostic value in patients with MBC. METHODS: Peripheral blood samples from 127 MBC patients were collected at baseline before starting a new treatment. The detection and enumeration of CAMLs and CTCs in 7.5 ml whole blood were performed using the CellSearch™ system. The associations of CAMLs and CTCs with the progression-free survival (PFS) and overall survival (OS) in the patients were evaluated using Kaplan-Meier curves and Cox proportional hazards modeling. RESULTS: Among 127 MBC patients, 21 (16.5%) were detected with CAMLs and 38 (29.9%) had elevated CTCs (≥5 CTCs/7.5 ml). Patients with CAMLs at baseline had worse PFS and OS with an adjusted hazard ratio (HR) of 1.75 (95% CI 1.03-2.98, P = 0.0374) and 3.75 (95% CI 1.52-9.26, P = 0.0042), compared to patients without CAMLs. Compared with patients with <5 CTCs and without CAMLs, patients with <5 CTCs and with CAMLs, with ≥5 CTCs but without CAMLs, or with ≥5 CTCs and with CAMLs, had an increasing trend of risk of disease progression (HR = 0.84, 3.42 and 4.04 respectively, P for trend <0.0001) and death (HR = 2.66, 6.14, and 9.13, respectively, P for trend <0.0001). CONCLUSION: Baseline enumeration of individual CAMLs is an independent indicator for MBC patients' survival. Evaluation of CAMLs in peripheral blood might provide a potential biomarker with additional prognostic values over CTC enumeration alone in MBC patients.

Longitudinally collected CTCs and CTC-clusters and clinical outcomes of metastatic breast cancer.

PURPOSE: Circulating tumor cell (CTC) is a well-established prognosis predictor for metastatic breast cancer (MBC), and CTC-cluster exhibits significantly higher metastasis-promoting capability than individual CTCs. Because measurement of CTCs and CTC-clusters at a single time point may underestimate their prognostic values, we aimed to analyze longitudinally collected CTCs and CTC-clusters in MBC prognostication. METHODS: CTCs and CTC-clusters were enumerated in 370 longitudinally collected blood samples from 128 MBC patients. The associations between baseline, first follow-up, and longitudinal enumerations of CTCs and CTC-clusters with patient progression-free survival (PFS) and overall survival (OS) were analyzed using Cox proportional hazards models. RESULTS: CTC and CTC-cluster counts at both baseline and first follow-up were significantly associated with patient PFS and OS. Time-dependent analysis of longitudinally collected samples confirmed the significantly unfavorable PFS and OS in patients with ≥5 CTCs, and further demonstrated the independent prognostic values by CTC-clusters compared to CTC-enumeration alone. Longitudinal analyses also identified a link between the size of CTC-clusters and patient OS: compared to the patients without any CTC, those with 2-cell CTC-clusters and ≥3-cell CTC-clusters had a hazard ratio (HR) of 7.96 [95 % confidence level (CI) 2.00-31.61, P = 0.003] and 14.50 (3.98-52.80, P < 0.001), respectively. CONCLUSIONS: In this novel time-dependent analysis of longitudinally collected CTCs and CTC-clusters, we showed that CTC-clusters added additional prognostic values to CTC enumeration alone, and a larger-size CTC-cluster conferred a higher risk of death in MBC patients.

Detection and Characterization of Circulating Tumor Associated Cells in Metastatic Breast Cancer.

The availability of blood-based diagnostic testing using a non-invasive technique holds promise for real-time monitoring of disease progression and treatment selection. Circulating tumor cells (CTCs) have been used as a prognostic biomarker for the metastatic breast cancer (MBC). The molecular characterization of CTCs is fundamental to the phenotypic identification of malignant cells and description of the relevant genetic alterations that may change according to disease progression and therapy resistance. However, the molecular characterization of CTCs remains a challenge because of the rarity and heterogeneity of CTCs and technological difficulties in the enrichment, isolation and molecular characterization of CTCs. In this pilot study, we evaluated circulating tumor associated cells in one blood draw by size exclusion technology and cytological analysis. Among 30 prospectively enrolled MBC patients, CTCs, circulating tumor cell clusters (CTC clusters), CTCs of epithelial-mesenchymal transition (EMT) and cancer associated macrophage-like cells (CAMLs) were detected and analyzed. For molecular characterization of CTCs, size-exclusion method for CTC enrichment was tested in combination with DEPArray™ technology, which allows the recovery of single CTCs or pools of CTCs as a pure CTC sample for mutation analysis. Genomic mutations of TP53 and ESR1 were analyzed by targeted sequencing on isolated 7 CTCs from a patient with MBC. The results of genomic analysis showed heterozygous TP53 R248W mutation from one single CTC and pools of three CTCs, and homozygous TP53 R248W mutation from one single CTC and pools of two CTCs. Wild-type ESR1 was detected in the same isolated CTCs. The results of this study reveal that size-exclusion method can be used to enrich and identify circulating tumor associated cells, and enriched CTCs were characterized for genetic alterations in MBC patients, respectively.

Edelfosine Promotes Apoptosis in Androgen-Deprived Prostate Tumors by Increasing ATF3 and Inhibiting Androgen Receptor Activity.

Edelfosine is a synthetic alkyl-lysophospholipid that possesses significant antitumor activity in several human tumor models. Here, we investigated the effects of edelfosine combined with androgen deprivation (AD) in LNCaP and VCaP human prostate cancer cells. This treatment regimen greatly decreased cell proliferation compared with single agent or AD alone, resulting in higher levels of apoptosis in LNCaP compared with VCaP cells. Edelfosine caused a dose-dependent decrease in AKT activity, but did not affect the expression of total AKT in either cell line. Furthermore, edelfosine treatment inhibited the expression of androgen receptor (AR) and was associated with an increase in activating transcription factor 3 (ATF3) expression levels, a stress response gene and a negative regulator of AR transactivation. ATF3 binds to AR after edelfosine + AD and represses the transcriptional activation of AR as demonstrated by PSA promoter studies. Knockdown of ATF3 using siRNA-ATF3 reversed the inhibition of PSA promoter activity, suggesting that the growth inhibition effect of edelfosine was ATF3 dependent. Moreover, expression of AR variant 7 (ARv7) and TMPRSS2-ERG fusion gene were greatly inhibited after combined treatment with AD and edelfosine in VCaP cells. In vivo experiments using an orthotopic LNCaP model confirmed the antitumor effects of edelfosine + AD over the individual treatments. A significant decrease in tumor volume and PSA levels was observed when edelfosine and AD were combined, compared with edelfosine alone. Edelfosine shows promise in combination with AD for the treatment of prostate cancer patients. Mol Cancer Ther; 15(6); 1353-63. ©2016 AACR.

A Phase I/II Study of the Investigational Drug Alisertib in Combination With Abiraterone and Prednisone for Patients With Metastatic Castration-Resistant Prostate Cancer Progressing on Abiraterone.

LESSONS LEARNED: Patients with metastatic castration-resistant prostate cancer did not tolerate the combination of alisertib with abiraterone and prednisone.There was no clear signal indicating that adding alisertib might be beneficial for those patients progressing on abiraterone. BACKGROUND: We hypothesized that Aurora A kinase (AK) contributes to castrate resistance in prostate cancer (PCa) and that inhibiting AK with alisertib can resensitize PCa cells to androgen receptor (AR) inhibitor abiraterone. METHODS: This was a phase I/II trial to determine the safety and efficacy of alisertib when given in combination with abiraterone plus prednisone (AP). Metastatic castration-resistant prostate cancer (mCRPC) patients were treated with dose escalation (alisertib at 30, 40, and 50 mg orally b.i.d., days 1-7 every 21 days) per standard 3+3 design. RESULTS: Nine of 43 planned subjects were enrolled. The maximum tolerated dose (MTD) was not reached, and the dose-limiting toxicities (DLTs) included neutropenic fever (1 of 9), neutropenia (1 of 9), fatigue with memory impairment (1 of 9), and diarrhea/mucositis (1 of 9). No prostate-specific antigen (PSA) decrease or circulating tumor cell (CTC) changes were observed during the study. Pharmacodynamically, adding alisertib did not affect total testosterone or dehydroepiandrosterone (DHEA) levels. There was some change in neuroendocrine markers after therapy. Mean duration on study was 2.5 months. The trial was terminated early. CONCLUSION: A tolerable dose of alisertib in combination with AP in mCRPC was not established in this study. There was no clear signal indicating that alisertib might be beneficial for patients with mCRPC progressing on abiraterone.

Prospective assessment of the prognostic value of circulating tumor cells and their clusters in patients with advanced-stage breast cancer.

The enumeration of circulating tumor cells (CTCs) provides important prognostic values in patients with metastatic breast cancer. Recent studies indicate that individual CTCs form clusters and these CTC-clusters play an important role in tumor metastasis. We aimed to assess whether quantification of CTC-clusters provides additional prognostic value over quantification of individual CTCs alone. In 115 prospectively enrolled advanced-stage (III and IV) breast cancer patients, CTCs and CTC-clusters were counted in 7.5 ml whole blood using the CellSearch system at baseline before first-line therapy. The individual and joint effects of CTC and CTC cluster counts on patients' progression-free survival (PFS) were analyzed using Cox proportional hazards modeling. Of the 115 patients, 36 (31.3 %) had elevated baseline CTCs (≥5 CTCs/7.5 ml) and 20 (17.4 %) had CTC-clusters (≥2 CTCs/7.5 ml). Patients with elevated CTCs and CTC-clusters both had worse PFS with a hazard ratio (HR) of 2.76 [95 % confidence interval (CI) 1.57-4.86, P log-rank = 0.0005] and 2.83 (1.48-5.39, P log-rank = 0.001), respectively. In joint analysis, compared with patients with <5 CTCs and without CTC-clusters, patients with elevated CTCs but without clusters, and patients with elevated CTCs and with clusters, had an increasing trend of progression risk, with an HR of 2.21 (1.02-4.78) and 3.32 (1.68-6.55), respectively (P log-rank = 0.0006, P trend = 0.0002). The additional prognostic value of CTC-clusters appeared to be more pronounced in patients with inflammatory breast cancer (IBC), the most aggressive form of breast cancer with the poorest survival. Baseline counts of both individual CTCs and CTC-clusters were associated with PFS in advanced-stage breast cancer patients. CTC-clusters might provide additional prognostic value compared with CTC enumeration alone, in patients with elevated CTCs.

The effects of erythropoiesis-stimulating agents on the short-term and long-term survivals in metastatic breast cancer patients receiving chemotherapy: a SEER population-based study.

Current clinical guidelines state that the use of erythropoiesis-stimulating agents (ESAs) may be considered to treat chemotherapy-induced anemia in the non-curative setting to alleviate anemia-related symptoms. However, no convincing survival benefit has been demonstrated to support the use of ESAs in these patients. Using the comprehensive data collected in the National Cancer Institute (NCI)-surveillance epidemiology and end results (SEER) and Medicare-linked database, we analyzed the effect of ESA use on the short-term (18-month) and long-term (60-month) survival rates of chemotherapy-treated metastatic breast cancer patients. Confounding variables were adjusted using a propensity score approach. We also analyzed the effects of ESA on the survival of patients receiving trastuzumab, a commonly prescribed targeted therapy agent in treating HER2-positive tumors. Metastatic breast cancer patients who received ESA treatment exhibited similar 60-month survival rate to those without ESA treatment (22.8 vs. 24.9%, p = 0.8). ESA-treated patients had a trend toward better 18-month survival [crude hazard ratio (HR) 0.86, 95% confidence intervals (CI) 0.68-1.09, p = 0.21]. This protective effect during the first 18 months of chemotherapy became marginally significant after adjusting for the propensity of receiving ESAs (HR 0.80, 95% CI 0.63-1.01, p = 0.070). An interaction effect between ESA and trastuzumab on patient survival was noticeable but not statistically significant. ESAs did not negatively affect the long-term survival of metastatic breast cancer patients. Moreover, ESAs improved patients' survival during the first 18 months of chemotherapy treatment. These findings endorse the current clinical guideline. Given the short survival of these patients, the potential short-term beneficial effects of ESAs are clinically meaningful.

Arterial Blood, Rather Than Venous Blood, is a Better Source for Circulating Melanoma Cells.

BACKGROUND: CTCs provide prognostic information and their application is under investigation in multiple tumor types. Of the multiple variables inherent in any such process, none is more important to outcome than the appropriateness of the sample source. To address this question, we investigated CTCs in paired peripheral venous and arterial blood specimens obtained from stage IV uveal melanoma patients. METHODS: Blood specimens were obtained from both common femoral arteries and antecubital veins in 17 uveal melanoma patients with multiple hepatic metastases for CTC measurements. FINDING: CTCs were detectable with greater frequency (100%) and in larger numbers (median 5, range 1 to 168) in all arterial blood specimens than in venous samples (52.9%; median 1, range 0 to 8). Patients with hepatic as well as extra-hepatic metastasis showed higher number of arterial CTCs, compared to patients with liver-only metastasis (p = 0.003). There was no significant association between the number of arterial CTCs and the tumor burden within the liver in patients who had liver-only metastases. INTERPRETATION: Our data indicate that arterial blood specimens might be a better source of circulating uveal melanoma cells. Although less conveniently processed, perhaps arterial blood should be evaluated as sample source for measurement of CTCs.

CTC enumeration and characterization: moving toward personalized medicine.

The primary cause of tumor-related death in breast cancer (BC) is still represented by distant metastasization. The dissemination of tumor cells from the primary tumor to distant sites through bloodstream cannot be early detected by standard imaging methods. The enumeration of circulating tumor cells (CTCs) represents an effective prognostic and predictive biomarker, which is able to monitor efficacy of adjuvant therapies, detect early development of (micro)metastases and at last, assess therapeutic responses of advanced disease earlier than traditional imaging methods. Moreover, since repeated tissue biopsies are invasive, costly and not always feasible, the assessment of tumor characteristics on CTCs, by a peripheral blood sample as a 'liquid biopsy', represents an attractive opportunity. The implementation of molecular and genomic characterization of CTCs could contribute to improve the treatment selection and thus, to move toward more personalized treatments. This review describes the current state of the art on CTC detection strategies, the evidence to demonstrate their clinical validity, and their potential impact for both future clinical trial design and, decision-making process in our daily practice.

AZD8931, an equipotent, reversible inhibitor of signaling by epidermal growth factor receptor (EGFR), HER2, and HER3: preclinical activity in HER2 non-amplified inflammatory breast cancer models.

INTRODUCTION: Epidermal growth factor receptor (EGFR) overexpression has been associated with prognostic and predictive value in inflammatory breast cancer (IBC). Epidermal growth factor receptor 2 (HER2) overexpression is observed at a higher rate in IBC compared with noninflammatory breast cancer. Current clinically available anti-HER2 therapies are effective only in patients with HER2 amplified breast cancer, including IBC. AZD8931 is a novel small-molecule equipotent inhibitor of EGFR, HER2, and HER3 signaling. In this study, we investigated the antitumor activity of AZD8931 alone or in combination with paclitaxel using preclinical models of EGFR-overexpressed and HER2 non-amplified IBC cells. METHODS: Two IBC cell lines SUM149 and FC-IBC-02 derived from pleural effusion of an IBC patient were used in this study. Cell growth and apoptotic cell death were examined in vitro. For the in vivo tumor growth studies, IBC cells were orthotopically transplanted into the mammary fat pads of immunodeficient mice. AZD8931 was given by daily oral gavage at doses of 25 mg/kg, 5 days/week for 4 weeks. Paclitaxel was subcutaneously injected twice weekly. RESULTS: AZD8931 significantly suppressed cell growth of IBC cells and induced apoptosis of human IBC cells in vitro. Significantly, we showed that AZD8931 monotherapy inhibited xenograft growth and the combination of paclitaxel + AZD8931 was demonstrably more effective than paclitaxel or AZD8931 alone treatment at delaying tumor growth in vivo in orthotopic IBC models. CONCLUSION: AZD8931 single agent and in combination with paclitaxel demonstrated signal inhibition and antitumor activity in EGFR-overexpressed and HER2 non-amplified IBC models. These results suggest that AZD8931 may provide a novel therapeutic strategy for the treatment of IBC patients with HER2 non-amplified tumors.

EZH2 knockdown suppresses the growth and invasion of human inflammatory breast cancer cells.

INTRODUCTION: Inflammatory breast cancer (IBC) is the most metastatic variant of breast cancer with the poorest survival in all types of breast cancer patients and presently therapeutic targets for IBC are very limited. Enhancer of zeste homolog 2 (EZH2) is frequently expressed in human IBC and its expression positively correlates with worse clinical outcome. However, the molecular basis for EZH2 promoting IBC has not been explored. Here, we investigated the functional role of EZH2 in IBC cells by examining the effects of its knockdown on the formation of tumor spheroids and invasion of these cells in vitro and in vivo in an orthotopic xenograft model. METHODS: SUM149 and a new IBC cell line-FC-IBC-02 derived from pleural effusion fluid of an IBC patient were used in this study. Specific knockdown of EZH2 was performed using short hairpin RNA (shRNA) specific to the human EZH2 gene. Cell growth and the formation of tumor spheroids were examined in vitro. The effects of EZH2 knockdown on IBC cell migration and invasion were examined by a Boyden chamber assay. For the in vivo tumor growth studies, IBC cells were orthotopically transplanted into the mammary fat pads of immunodeficient mice. RESULTS: The results showed that EZH2 is expressed at higher levels in human IBC cell lines compared with normal human mammary epithelial cells, and the knockdown of EZH2 expression significantly suppressed cell growth and tumor spheroid formation of human IBC cells in vitro. In addition, EZH2 knockdown inhibited the migration and invasion of IBC cells. Significantly, EZH2 knockdown suppressed the angiogenesis and tumor growth of IBC cells in vivo. CONCLUSIONS: Our results provide direct evidence that EZH2 is critical for the formation of tumor spheroids and invasion of human IBC cells and could be a potential target for developing novel therapeutic strategies for human IBC.

Presence of anaplastic lymphoma kinase in inflammatory breast cancer.

Although Inflammatory Breast Cancer (IBC) is recognized as the most metastatic variant of locally advanced breast cancer, the molecular basis for the distinct clinical presentation and accelerated program of metastasis of IBC is unknown. Reverse phase protein arrays revealed activation of the receptor tyrosine kinase, anaplastic lymphoma kinase (ALK) and biochemically-linked downstream signaling molecules including JAK1/STAT3, AKT, mTor, PDK1, and AMPKß in pre-clinical models of IBC. To evaluate the clinical relevance of ALK in IBC, analysis of 25 IBC patient tumors using the FDA approved diagnostic test for ALK genetic abnormalities was performed. These studies revealed that 20/25 (80%) had either increased ALK copy number, low level ALK gene amplification, or ALK gene expression, with a prevalence of ALK alterations in basal-like IBC. One of 25 patients was identified as having an EML4-ALK translocation. The generality of gains in ALK copy number in basal-like breast tumors with IBC characteristics was demonstrated by analysis of 479 breast tumors using the TGCA data-base and our newly developed 79 IBC-like gene signature. The small molecule dual tyrosine kinase cMET/ALK inhibitor, Crizotinib (PF-02341066/Xalkori®, Pfizer Inc), induced both cytotoxicity (IC50 = 0.89 µM) and apoptosis, with abrogation of pALK signaling in IBC tumor cells and in FC-IBC01 tumor xenograft model, a new IBC model derived from pleural effusion cells isolated from an ALK(+) IBC patient. Based on these studies, IBC patients are currently being evaluated for the presence of ALK genetic abnormalities and when eligible, are being enrolled into clinical trials evaluating ALK targeted therapeutics.

Inflammatory breast cancer (IBC): clues for targeted therapies.

Inflammatory breast cancer (IBC) is the most aggressive type of advanced breast cancer characterized by rapid proliferation, early metastatic development and poor prognosis. Since there are few preclinical models of IBC, there is a general lack of understanding of the complexity of the disease. Recently, we have developed a new model of IBC derived from the pleural effusion of a woman with metastatic secondary IBC. FC-IBC02 cells are triple negative and form clusters (mammospheres) in suspension that are strongly positive for E-cadherin, ß-catenin and TSPAN24, all adhesion molecules that play an important role in cell migration and invasion. FC-IBC02 cells expressed stem cell markers and some, but not all of the characteristics of cells undergoing epithelial mesenchymal transition (EMT). Breast tumor FC-IBC02 xenografts developed quickly in SCID mice with the presence of tumor emboli and the development of lymph node and lung metastases. Remarkably, FC-IBC02 cells were able to produce brain metastasis in mice on intracardiac or intraperitoneal injections. Genomic studies of FC-IBC02 and other IBC cell lines showed that IBC cells had important amplification of 8q24 where MYC, ATAD2 and the focal adhesion kinase FAK1 are located. MYC and ATAD2 showed between 2.5 and 7 copies in IBC cells. FAK1, which plays important roles in anoikis resistance and tumor metastasis, showed 6-4 copies in IBC cells. Also, CD44 was amplified in triple-negative IBC cells (10-3 copies). Additionally, FC-IBC02 showed amplification of ALK and NOTCH3. These results indicate that MYC, ATAD2, CD44, NOTCH3, ALK and/or FAK1 may be used as potential targeted therapies against IBC.