A Novel Filtration Membrane for Clustered Circulating Tumor Cell Extraction: A Prospective Feasibility Study.

BACKGROUND/AIM: Circulating tumor cells (CTCs) have garnered attention as biomarkers for therapeutic response and prognosis in malignant neoplasms. Nonetheless, existing literature predominantly relies on surrogate markers of tumor cells or focuses on single-cell CTC, failing to adequately address the challenge of detecting cluster-forming CTCs, which bear considerable prognostic implications. This prospective study aims to validate the efficacy of a novel filtration membrane, namely Soft Micro Pore Filter (S-MPF®), for rare cell recovery in detecting CTCs through the analysis of clinical samples. PATIENTS AND METHODS: Patients with confirmed lung cancer or highly suspected lung cancer based on specific criteria (solid tumor size >2.0 cm, serum carcinoembryonic level >7.5 ng/ml, maximum standard uptake value derived from fluorodeoxyglucose-position emission tomography >2.9) were included in the study. CTCs were extracted from preoperative peripheral arterial blood samples using S-MPF®, and the validity of the filtration system was positively verified. RESULTS: Out of the 25 enrolled patients, 23 had lung cancer. CTC positivity was observed in 17 cases (73.9%), whereas cluster CTC positivity was observed in 16 cases (69.6%), with a median count of two clusters. Single CTC positivity was observed in 11 cases (52.1%), with a median count of one cell. CONCLUSION: The utilization of the newly developed S-MPF® filtration membrane exhibited a high rate of CTC identification, demonstrating its suitability for clinical applications.

Verification of A New Filter for Isolation of Circulating Tumor Cells by Only Blood Filtration.

BACKGROUND/AIM: Since circulating tumor cells (CTCs) are precursors of metastatic lesions, extracting CTCs from whole blood is useful in obtaining information for cancer treatment. One of the CTC isolation methods is the size selection method; however, since the conventional methods are expensive and cumbersome, we developed an affordable and simple filter, whose usefulness is verified in this study. MATERIALS AND METHODS: The new filter [hereafter, soft micropore filter (S-MPF)] is made up of a polyethylene film with a thickness of 15 µm and conical pores having a diameter of 8-10 µm, which are opened uniformly (opening rate, 20%). This filter can filter whole blood by free-falling under gravity. The possibilities of the filter's usage for model CTC isolation, immunostaining, short-term cell culture, and gene mutation detection in extracted model CTCs were verified. RESULTS: S-MPF was able to extract model CTCs with an isolation rate of up to 15%. These model CTCs were detected by cytology, immunostaining, and culture by short-term incubation of filtered cells. Furthermore, genetic mutations were identified in the cultured cells. In addition, CTC isolation from the peripheral blood of patients with lung cancer was demonstrated by setting the volume of collected blood to 15 ml to prevent a low recovery rate. CONCLUSION: The S-MPF can be used to extract model CTCs quickly and easily. Moreover, cytological diagnosis, immunostaining, short-term culture, and gene mutation search are possible with this filter. Given its proven applicability in clinical samples, this filter can be used in clinical settings.

Evaluation of DNA/RNA quality from cell block of malignant mesothelioma and lung adenocarcinoma.

Malignant mesothelioma (MM) is a rare and highly lethal tumor that arises from mesothelial tissue on the surface of the chest and abdominal cavity. Cytological examination of body fluids, including pleural fluid and ascites, is essential for the differentiation of malignant mesothelioma from other carcinomas, such as lung and gastrointestinal carcinomas and metastatic tumors. To evaluate the effectiveness of cell block preparation procedures, which are used for immunocytochemical staining and genetic panel analysis of tumor-specific gene mutations, we used various fixatives. We also evaluated the effects of immunostaining, and the quality of nucleic acids for genetic analysis. METHODS: Cell blocks were prepared using the malignant mesothelioma cell lines MESO4 and H226 and non-small cell lung carcinoma cell line HCC78. The cells were fixed using 10% neutral buffered formalin and four different fixatives for liquid cytology. Fixed cells were formed into cell clusters using sodium alginate or centrifugation, and paraffin-embedded cell blocks were prepared. RESULTS: Cell blocks were morphologically evaluated by hematoxylin and eosin and immunocytological staining, and the nucleic acid quality was evaluated by DNA/RNA extraction, qPCR, and next-generation sequence analysis. D2-40 and WT1 staining differed depending on the fixation solution and the cell cluster formation method; however, the degree of nucleic acid degradation was not impaired by any method. CONCLUSION: Although the morphological evaluation of cytology specimens is affected by the method of cell block preparation, it is still useful for nucleic acid extraction and gene panel analysis, as long as there are sufficient amounts of tumor cells.

A study on preserving endometrial glandular architecture during preparation using BD SurePath™ liquid-based cytology reagents: Cellular fixation with preservative fluid requires at least 18 h.

INTRODUCTION: This study aimed to determine the causes of disruption of the three-dimensional architecture of endometrial glands prepared using BD SurePath™ liquid-based cytology (SP-LBC) reagents. One sample preparation method for endometrial cytology is presented in which this three-dimensional architecture can be retained. METHODS: SP-LBC specimens were prepared by the following three methods: (1) using the BD PrepMateTM (PrepMate) System after cellular fixation for 1-6 h (method A); (2) without using the PrepMate System after cellular fixation for 1-6 h (method B); and (3) using the PrepMate System after cellular fixation for at least 18 h (method C). Size and numbers of endometrial cell clusters and numbers of solitary scattered cells were then evaluated. RESULTS: Significantly higher numbers of cell clusters with a major axis of 200 µm or more were yielded by method C (71.3 ± 57.2) than methods A (9.3 ± 5.9, P < 0.001) or B (44.3 ± 28.8, P < 0.05). Method B yielded significantly higher numbers of cell clusters than method A (P < 0.001). Method A (132.2 ± 107.7, p < 0.001) yielded significantly higher numbers of solitary scattered cells than methods B (29.1 ± 14.8) and C (35.7 ± 23.3). No significant difference in solitary cell numbers was found between methods B and C. CONCLUSIONS: Retention of endometrial glandular architecture is rendered possible by allowing sample fixation times of 18 h or more when preparing specimens using the PrepMate System.

Molecular Analysis of Liquid-Based Cytological Specimen Using Virtually Positive Sputum with Adenocarcinoma Cells.

Liquid-based cytology (LBC) analysis of sputum is a useful diagnostic and prognostic tool for detecting lung cancer. DNA and RNA derived from lung cancer cells can be used for this diagnosis. However, the quality of cytological material is not always adequate for molecular analysis due to the effect of formalin in the commercially available fixation kits. In this study, we examined DNA and RNA extraction methods for LBC analysis with formalin fixation, using lung carcinoma cell lines and sputum. The human non-small cell lung cancer cell lines were fixed with LBC fixation reagents, such as CytoRich red preservative. Quantification of thyroid transcription factor-1 (TTF-1) and actin mRNA, epidermal growth factor receptor (EGFR) DNA in HCC827, H1975, and H1299 cells, and mutation analysis of EGFR in HCC827 and H1975 cells were performed by quantitative PCR (qPCR) and fluorescence resonance energy transfer (FRET)-based preferential homoduplex formation assay (F-PHFA) method, respectively. mRNA and DNA extracted from cell lines using RNA and/or DNA extraction kits for formalin-fixed paraffin-embedded (FFPE) fixed with various LBC solutions were efficiently detected by qPCR. The detection limit of EGFR mutations was at a rate of 5% mutated positive cells in LBC. The detection limit of the EGFR exon 19 deletion in HCC827 was detected in more than 1.5% of the positive cells in sputum. In contrast, the detection limit of the T790M/L858R mutation in H1975 was detected in more than 13% of the positive cells. We also detected EGFR mutations using next generation sequencing (NGS). The detection limit of NGS for EGFR mutation was lower than that of the F-PHFA method. Furthermore, more than 0.1% of positive cells could be cytomorphologically detected. Our results demonstrate that LBC systems are powerful tools for cytopathological and genetic analyses. However, careful attention should be paid to the incidence of false negative results in the genetic analysis of EGFR mutations detected by LBC.

High expression of organic anion transporter 2 and organic cation transporter 2 is an independent predictor of good outcomes in patients with metastatic colorectal cancer treated with FOLFOX-based chemotherapy.

Although metastatic colorectal cancer (mCRC) is commonly treated with 5-fluorouracil (5-FU)/leucovorin/oxaliplatin (FOLFOX), their response to FOLFOX varies, and no biomarkers predictive of treatment outcome have been validated. Organic anion transporter 2 (OAT2) and organic cation transporter 2 (OCT2) are critical determinants in uptake of 5-FU and oxaliplatin, respectively. In this study, we evaluated whether OAT2 and OCT2 levels can predict effectiveness of FOLFOX-based therapy. We retrospectively assessed 90 patients with mCRC who were treated with first-line FOLFOX with or without bevacizumab. We immunohistochemically determined OAT2 and OCT2 expression levels at invasion fronts of their tumors and correlated the levels to clinicopathological parameters, including objective tumor response (OTR) and progression-free survival (PFS). High expression of OAT2 (OAT2(High)) and OCT2 (OCT2(High)) were detected in 36% and 60% of the tumors, respectively. OCT2(High) was significantly associated with invasion depth (P=0.03), whereas OAT2(High) was not associated with any clinicopathological parameters. In univariate analysis, OAT2(High) was significantly correlated with good OTR (P=0.02), and OCT2(High) with long PFS (P=0.03). Multivariate analyses showed that OAT2(High) and OCT2(High), respectively, were the sole independent predictors of good OTR (P=0.02) and long PFS (P=0.03). We found that patients with OAT2(High)/OCT2(High) showed the best treatment outcomes (good OTR and long PFS) with significantly higher frequency than patients with other expression patterns (P=0.003). OAT2(High)/OCT2(High) status was also the only independent predictive factor in multivariate analysis. This study suggests that OAT2(High) and OCT2(High) are important independent predictors of good outcomes in FOLFOX-treated mCRC.

Expression of organic anion-transporting polypeptide 1A2 and organic cation transporter 6 as a predictor of pathologic response to neoadjuvant chemotherapy in triple negative breast cancer.

Organic anion-transporting polypeptide 1A2 (OATP1A2) and organic cation transporter 6 (OCT6) are involved in the uptake of taxanes and anthracyclines, respectively. The aim of this study was to evaluate expression levels of OATP1A2 and OCT6 as a predictor of response to neoadjuvant chemotherapy (NAC) in breast cancer. A total of 124 patients who received anthracycline/taxane-based NAC were included. Expression levels of OATP1A2 and OCT6 were immunohistochemically assessed in core needle biopsies obtained prior to NAC. A pathologic good response (pGR) and a pathologic complete response (pCR) were achieved in 24 and 10 % of patients, respectively. In univariate analysis of the entire cohort, negative hormone receptor (HR) status (pGR and pCR, P < 0.001), high Ki-67 level (pGR, P = 0.03; pCR, P = 0.02), triple negative (TN) subtype (pGR, P = 0.001; pCR, P < 0.001), and high OCT6 (pGR, P = 0.003) were associated with the response. In combined analysis, high OATP1A2/high OCT6 level was also a significant factor for pGR (P = 0.001) and pCR (P = 0.001). Two separate multivariate analyses showed that HR status, TN subtype and combined high OATP1A2/high OCT6 level were significant independent predictors. When TN and non-TN tumors were assessed separately in univariate analysis, high Ki-67 level (P = 0.04) were associated with pGR and combined high OATP1A2/high OCT6 level was associated with both pGR (P = 0.005) and pCR (P = 0.03) in the TN group. Multivariate analysis identified the combined high OATP1A2/high OCT6 level as the sole independent predictor of pGR. In the non-TN group, negative HR status (P = 0.03) and positive HER2 status (P = 0.005) were associated with pGR, but HER2 status was the sole independent predictor of pGR. These results suggest that response-associated predictors may differ between the TN and non-TN tumors. Combined high OATP1A2/high OCT6 may be a potential predictor of response to anthracycline/taxane-based chemotherapy in breast cancer, especially in TN tumors.

Organic cation transporter 2 and tumor budding as independent prognostic factors in metastatic colorectal cancer patients treated with oxaliplatin-based chemotherapy.

Oxaliplatin is currently approved for patients with metastatic colorectal cancer (mCRC). Its uptake and consequent cytotoxicity is determined by the levels of organic cation transporter 2 (OCT2). In addition, tumor budding (TB) is associated with high malignant potential. However, the impact of the levels of OCT2 and TB on clinicopathological findings and the prognosis of mCRC patients treated with oxaliplatin-based chemotherapy remains unclear. Here, 80 mCRC patients were retrospectively assessed. Immunohistochemistry was performed to determine the levels of OCT2 and TB. High levels of OCT2 (47/80, 59%) were detected at the invasion front and were associated with depth of invasion (P=0.03), whereas high levels of TB (40/80, 50%) were associated with extensive lymphatic invasion (P=0.03). In univariate analysis, high OCT2 levels were significantly correlated with longer progression-free survival (PFS) (P=0.02) whereas high TB levels were associated with shorter PFS (P=0.01). In combined analysis, patients with 2 favorable factors (high OCT2/low TB) had longer PFS than those with 1 (P=0.03) or 0 (P<0.001) favorable factors. Multivariate analysis confirmed that the OCT2 level (P=0.007), TB level (P=0.004), and combined OCT2/TB status (P=0.001) were independent predictors for PFS. These results suggest that high levels of OCT2 indicate severe invasion, but also better prognosis in mCRC patients treated with oxaliplatin-based chemotherapy, possibly because of its role in oxaliplatin susceptibility. Combined analysis of OCT2 and TB status may guide the selection of patients for successful oxaliplatin-based chemotherapy.