Evaluation of a novel approach to circulating tumor cell isolation for cancer gene panel analysis in patients with breast cancer

Phenotyping of rare circulating cells in the blood of non-metastatic breast cancer patients using microfluidic Labyrinth technology

Label-free technologies for isolating rare circulating cells in breast cancer patients are widely available; however, they are mostly validated on metastatic patient blood samples. Given the need to use blood-based biomarkers to inform on disease progression and treatment decisions, it is important to validate these technologies in non-metastatic patient blood samples. In this study, we specifically focus on a recently established label-free microfluidic technology Labyrinth and assess its capabilities to phenotype a variety of rare circulating tumor cells indicative of epithelial-to-mesenchymal transition as well as cancer-associated macrophage-like (CAML) cells. We specifically chose a patient cohort that is non-metastatic and selected to undergo neoadjuvant chemotherapy to assess the performance of the Labyrinth technology. We enrolled 21 treatment naïve non-metastatic breast cancer patients of various disease stages. Our results indicate that (i) Labyrinth microfluidic technology is successfully able to isolate different phenotypes of CTCs despite the counts being low. (ii) Invasive phenotypes of CTCs such as transitioning CTCs and mesenchymal CTCs were found to be present in high numbers in stage III patients as compared to stage II patients. (iii) As the total load of CTCs increased, the mesenchymal CTCs were found to be increasing. (iv) Labyrinth was able to isolate CAMLs with the counts being higher in stage III patients as compared to stage II patients. Our study demonstrates the ability of the Labyrinth microfluidic technology to isolate rare cancer-associated cells from the blood of treatment naïve non-metastatic breast cancer patients, laying the foundation for tracking oncogenic spread and immune response in patients undergoing neoadjuvant chemotherapy.

Fast, Reusable, Cell Uniformly Distributed Membrane Filtration Device for Separation of Circulating Tumor Cells

Isolation of circulating tumor cells (CTCs) is of great significance for the diagnosis, prognosis, and treatment of metastatic cancer. Among CTC capture methods independent of antibodies, membrane filtration-based methods have the advantages of simplicity, rapidity, and high throughput but usually have problems such as clogging, high pressure drop, and impaired cell viability. In this study, we designed and tested a reusable device that used horizontal rotor and fluid-assisted separation to capture CTCs by centrifugal membrane filtration, achieving simple, fast, highly efficient, and viable cell capture on traditional centrifuge. The average capture efficiency was 95.8% for different types of cancer cells with >90% survival, and the removal of white blood cells can reach 99.72% under four times cleaning of the membrane after filtration. A further clinic demo was performed using the device to detect residual leukemic cells in patients; the results showed a 10-fold enrichment of the leukemic cells in peripheral blood samples. Taken together, the simple, robust, and efficient CTC capture device may have the potential for clinic routine detection and analysis of circulating tumor cells.

The Polemic Diagnostic Role of TP53 Mutations in Liquid Biopsies from Breast, Colon and Lung Cancers

Being minimally invasive and thus allowing repeated measures over time, liquid biopsies are taking over traditional solid biopsies in certain circumstances such as those for unreachable tumors, very early stages or treatment monitoring. However, regarding TP53 mutation status analysis, liquid biopsies have not yet substituted tissue samples, mainly due to the lack of concordance between the two types of biopsies. This needs to be examined in a study-dependent manner, taking into account the particular type of liquid biopsy analyzed, that is, circulating tumor cells (CTCs) or cell-free DNA (cfDNA), its involvement in the tumor biology and evolution and, finally, the technology used to analyze each biopsy type. Here, we review the main studies analyzing TP53 mutations in either CTCs or cfDNA in the three more prevalent solid tumors: breast, colon and lung cancers. We evaluate the correlation for mutation status between liquid biopsies and tumor tissue, suggesting possible sources of discrepancies, as well as evaluating the clinical utility of using liquid biopsies for the analysis of TP53 mutation status and the future actions that need to be undertaken to make liquid biopsy analysis a reality for the evaluation of TP53 mutations.

Analysis of the serial circulating tumor cell count during neoadjuvant chemotherapy in breast cancer patients

We evaluated the prognostic implications of the circulating tumor cell (CTC) count in non-metastatic, HER2-negative breast cancer patients who failed to achieve pathologic complete response (pCR) after neoadjuvant chemotherapy (NCT). A total of 173, non-metastatic breast cancer patients treated with NCT were prospectively enrolled. CTCs were obtained from blood drawn pre-NCT and post-NCT using a SMART BIOPSY SYSTEM isolation kit (Cytogen Inc., Seoul, Korea) with immunofluorescence staining. Excluding 26 HER2-positive patients, Relapse-free survival (RFS) and overall survival (OS) related to the CTC count and the association of the CTC count with the treatment response to given therapy were analyzed in 147 HER2-negative patients. Among 147 HER2-negative patients, 28 relapses (19.0%) and 13 deaths (8.8%, all breast cancer-specific) were observed during a median follow-up of 37.3 months. One hundred and seven patients (72.8%) were hormone receptor-positive, and 40 patients (27.2%) had triple-negative breast cancer (TNBC). One or more CTCs were identified in 88 of the 147 patients (59.9%) before NCT and 77 of the 134 patients (52.4%) after NCT. In the entire HER2-negative patient cohort, the initial nodal status was the most significant factor influencing RFS and OS. In TNBC, 11 patients (27.5%) achieved pCR and patients that failed to achieve pCR with ≥ 5 CTCs after NCT, showed worse RFS (HR, 10.66; 95% CI, 1.80–63.07; p = 0.009) and OS (HR, 14.00; 95% CI, 1.26–155.53; p = 0.032). The patients with residual tumor and a high number of the CTCs after NCT displayed the worse outcome. These findings could provide justification to launch a future, well designed trial with longer follow-up data to obtain regulatory approval for clinical use of the assay, especially for the ER-positive, HER2-negative breast cancer subset.

Microfluidics for label-free sorting of rare circulating tumor cells

A review discussing the working principles and performances of label-free CTC sorting methods.

Dissection of major cancer gene variants in subsets of circulating tumor cells in advanced breast cancer

Enumeration of circulating tumor cells (CTCs) may reflect the metastatic potential of breast cancer (BC). By using the DEPArray, we investigated CTCs with respect to their epithelial-to-mesenchymal transition phenotype and compared their genomic heterogeneity with tissue biopsies. Seventeen stage IV BC patients were enrolled. Pre-enriched CTC suspensions were stained with fluorescent-labeled antibodies to epithelial (E) and mesenchymal (M) markers. CTC samples were processed by DEPArray system and clustered in relation to their markers. DNA from CTCs, as well as from primary tumor samples, was sequenced by next generation sequencing to assess the mutational state of 50 major cancer-related genes. We identified four different CTC subsets that harbored different gene variants. The most heterogenous CTC subsets included the M+/E− phenotype, which, however, expressed only 7 repeatedly mutated genes, while in the M−/E+ subset multiple mutations affected only 2 out of 50 genes. When matching all gene variants among CTC subsets, a small number of mutations was shared by only 4 genes, namely ATM, FGFR3, PIK3CA, and TP53 that, however, were absent in primary tumors. Our results postulate that the detected mutations in all CTC subsets may be considered as genomic markers of metastatic dissemination to be investigated during early stages of BC.