Circulating tumor cells (CTCs) are highly correlated with the invasive behavior of cancer, so their isolations and quantifications are important for biomedical applications such as cancer prognosis and measuring the responses to drug treatments. In this paper, we present the development of a microfluidic device for the separation of CTCs from blood cells based on the physical properties of cells. For use as a CTC model, we successfully separated human breast cancer cells (MCF-7) from a spiked blood cell sample by combining multi-orifice flow fractionation (MOFF) and dielectrophoretic (DEP) cell separation technique. Hydrodynamic separation takes advantage of the massive and high-throughput filtration of blood cells as it can accommodate a very high flow rate. DEP separation plays a role in precise post-processing to enhance the efficiency of the separation. The serial combination of these two different sorting techniques enabled high-speed continuous flow-through separation without labeling. We observed up to a 162-fold increase in MCF-7 cells at a 126 µL min⁻¹ flow rate. Red and white blood cells were efficiently removed with separation efficiencies of 99.24% and 94.23% respectively. Therefore, we suggest that our system could be used for separation and detection of CTCs from blood cells for biomedical applications.

Breast cancer (BC) in the Asia Pacific regions is enriched in younger patients and rapidly rising in incidence yet its molecular bases remain poorly characterized. Here we analyze the whole exomes and transcriptomes of 187 primary tumors from a Korean BC cohort (SMC) enriched in pre-menopausal patients and perform systematic comparison with a primarily Caucasian and post-menopausal BC cohort (TCGA). SMC harbors higher proportions of HER2+ and Luminal B subtypes, lower proportion of Luminal A with decreasedESR1expression compared to TCGA. We also observe increased mutation prevalence affectingBRCA1,BRCA2, andTP53in SMC with an enrichment of a mutation signature linked to homologous recombination repair deficiency in TNBC. Finally, virtual microdissection and multivariate analyses reveal that Korean BC status is independently associated with increased TIL and decreased TGF-β signaling expression signatures, suggesting that younger Asian BCs harbor more immune-active microenvironment than western BCs.

To elucidate the effects of neoadjuvant chemotherapy (NAC), we conduct whole transcriptome profiling coupled with histopathology analyses of a longitudinal breast cancer cohort of 146 patients including 110 pairs of serial tumor biopsies collected before treatment, after the first cycle of treatment and at the time of surgery. Here, we show that cytotoxic chemotherapies induce dynamic changes in the tumor immune microenvironment that vary by subtype and pathologic response. Just one cycle of treatment induces an immune stimulatory microenvironment harboring more tumor infiltrating lymphocytes (TILs) and up-regulation of inflammatory signatures predictive of response to anti-PD1 therapies while residual tumors are immune suppressed at end-of-treatment compared to the baseline. Increases in TILs and CD8+ T cell proportions in response to NAC are independently associated with pathologic complete response. Further, on-treatment immune response is more predictive of treatment outcome than immune features in paired baseline samples although these are strongly correlated.

Background. Forkhead Box Protein 3 (FOXP3) is a marker for immunosuppressive CD4+CD25+ regulatory T cells (Tregs). We investigated whether there were significant numbers of FOXP3-positive Tregs in triple-negative breast cancer (TNBC) using immunohistochemistry, and whether the presence of FOXP3-positive Tregs was associated with other prognostic factors, such as stage or histologic grade. We investigated the number of tumor-infiltrating FOXP3-positive Tregs in formalin-fixed TNBC specimens obtained from patients who received palliative treatment between 1999 and 2007. Material and methods. Immunohistochemistry was used to assess the number of CD4+, CD25+, and FOXP3+ Tregs in tumor tissue and normal breast tissue from 86 TNBC patients. Univariate and multivariate analyses evaluated outcomes according to the number of FOXP3-positive Tregs. Results. Of the 86 tumor specimens, 22 (25.6%) expressed more than 15 FOXP3-positive Tregs per 10 high power fields in the peritumoral area. On multivariate analysis, staining showing ≥ 15 FOXP3-positive Tregs was an independent prognostic factor for overall survival and progression free survival with hazard ratios of 2.4 (95% CI 1.0–5.6; p = 0.049) and 2.0 (95% CI 1.1–3.6; p = 0.032), respectively. In TNBC, FOXP3-positive Tregs had stronger prognostic significance than did FOXP3-negative Tregs. The finding of improved survival associated with highly infiltrating FOXP3-positive Tregs in TNBC contrasted with several other types of solid cancer. Conclusion. TNBC may be differently driven by FOXP3 via an immune mechanism. The inclusion of FOXP3+ Tregs may help to improve prognostication for TNBC.

Leptomeningeal metastasis (LM) usually occurs late during the course of breast cancer. The aim of this study was to characterize the clinical features and outcomes of LM based on breast cancer subtypes in conjunction with brain parenchymal metastases. A retrospective study was performed of breast cancer patients with LM, who received palliative management at Samsung Medical Center between 1995 and 2008. Among the 272 metastatic breast cancer patients with central nervous system (CNS) involvement, 68 patients with LM were identified. The median age was 46 years (range, 24–72 years). The median survival duration from LM to death (LM-OS) was 4.5 months (range, 0.2–26.4 months). Patients surviving for 12 or more months were rarer among triple negative (TN) patients compared to other subtypes (21.7% for HR + ve vs. 27.8% for HER2 + ve vs. 72.7% for TN, P = 0.217). Death caused by CNS involvement appeared to be much more common in TN than in other subtypes (0% for HR + ve vs. 36% for HER2 + ve vs. 64% for TN, P = 0.060). Median survival time from distant metastasis was significantly different among the three groups (28.3 vs. 29.1 vs. 11.8 months, P < 0.0001). However, median survival time from LM did not differ (4.1 vs. 5.9 vs. 3.8 months, P = 0.226). Characteristic manifestations and treatment outcomes of LM may be affected by the unique biology of breast cancer intrinsic subtypes. The different roles of active combined treatment modalities including both systemic chemotherapy and local treatment modalities should be considered to improve outcomes.