Detection of circulating tumor cells in patients with gastrointestinal tract cancer using RT-PCR and its clinical implications

Clinical significance of circulating tumor cells in the response to trastuzumab for HER2-negative metastatic gastric cancer

PURPOSE

The prognosis of metastatic gastric cancer has improved due to trastuzumab in patients with HER2 positive. Circulating tumor cells (CTCs) have been examined as a prognostic predictor in gastric cancer. The clinical advantage of trastuzumab was examined in gastric cancer patients with HER2-negative tumor tissues and HER2-positive CTCs.

METHODS

A total of 105 patients with metastatic or recurrence gastric cancer were enrolled. All patients were examined HER2 expression in CTC using the CellSearch system in blood specimens.

RESULTS

CTCs were detected in 65 of 105 patients (61.9%) and 61 patients were divided into three groups: Group A (n = 27), histological HER2-positive; Group B (n = 17), histological HER2-negative and HER2-positive CTCs; and Group C (n = 17), HER2-negative on histology and CTCs. Patients received capecitabine plus cisplatin. Groups A and B were additionally treated by trastuzumab. There was no relationship between tumor tissues and CTCs in HER2 expression. Even if group B had no histological HER2 expression, group B showed a good prognosis as same as group A, and group C had a significantly worse overall survival than groups A and B. The multivariate analysis demonstrated that HER2-expression on CTCs was an independent prognostic factor for both overall and progression-free survival.

CONCLUSION

The present results indicate the potential clinical utility of trastuzumab combined chemotherapy in patients with HER2-positive CTCs even if they are histologically HER2-negative.

Detection of Circulating Tumor Cells and Circulating Tumor Microemboli in Gastric Cancer

PURPOSE: Gastric cancer studies indicated a potential correlation between circulating tumor cells (CTCs) in peripheral blood and tumor relapse/metastasis. The prevalence and significance of circulating tumor microemboli (CTM) in gastric cancer remain unknown. We investigated the prevalence and prognostic value of CTCs and CTM for progression-free survival (PFS) and overall survival (OS) in gastric cancer patients. METHODS:Eighty-one gastric cancer patients consented to provide 5 ml of peripheral blood before systematic therapy. CTCs and CTM were isolated using isolation by size of epithelial tumor cells and characterized by cytopathologists. For 41 stage IV gastric cancer patients, CTM was investigated as a potential biomarker to predict prognosis. RESULTS:CTCs were detected in 51 patients; the average count was 1.81. In clinical stage I, II, III, and IV patients, the average CTC counts were 1.40, 0.67, 1.24, and 2.71, respectively. CTM were detected in 3 of 33 clinical stage I to IIIb patients, at an average of 0.12 (0-2). CTM were detected in 13 of 53 clinical stage IIIc to IV patients, at an average of 1.26 (0-22). In stage IV patients, CTM positivity correlated with the CA125 level. PFS and OS in CTM-positive patients were significantly lower than in CTM-negative patients (P < .001). CTM positivity was an independent factor for determining the PFS (P = .016) and OS (P = .003) of stage IV patients in multivariate analysis. Using markers of the epithelial-mesenchymal transition, single CTCs were divided into three phenotypes including epithelial CTCs, biphenotypic epithelial/mesenchymal CTCs, and mesenchymal CTCs. For CTM, CK−/Vimentin+/CD45− and CK+/Vimentin+/CD45− phenotypes were observed, but the CK+/Vimentin−/CD45− CTM phenotype was not. CA125 was detected in gastric cancer cell lines BGC823 and MGC803. CONCLUSIONS: In stage IV patients, CTM positivity was correlated with serum CA125 level. CTM were an independent predictor of shorter PFS and OS in stage IV patients. Thus, CTM detection may be a useful tool to predict prognosis in stage IV patients.

Clinical Significance of Circulating Tumor Cells in Peripheral Blood of Patients with Esophageal Squamous Cell Carcinoma

BACKGROUND

Esophageal squamous cell carcinoma is an aggressive gastrointestinal tract cancer. To date, the presence of circulating tumor cells (CTC) has been reported as a prognostic factor in peripheral blood from patients with gastrointestinal cancers.

METHODS

The CellSearch system was used to isolate and enumerate CTCs. A total of 90 patients with esophageal squamous cell carcinoma who received chemotherapy or chemoradiotherapy were enrolled. Peripheral blood specimens were collected before and after treatments.

RESULTS

At baseline analysis, CTCs were detected in 25 patients (27.8 %). Overall survival was significantly shorter in patients with than without CTCs. Follow-up blood specimens were obtained from 71 patients. Partial response, stable disease, and progressive disease after treatment were seen in 32, 12, and 27 patients, respectively. CTC positivity after treatment in the progressive disease group (40.7 %) was significantly higher than that of the partial response group (6.3 %). Patients with a change in CTC status from positive to negative had a good prognosis as well as patients without baseline CTCs.

CONCLUSIONS

Evaluation of CTCs may be a promising indicator for predicting tumor prognosis and the clinical efficacy of chemotherapy or chemoradiation therapy in patients with esophageal squamous cell carcinoma.

Liquid biopsy of gastric cancer patients: Circulating tumor cells and cell-free nucleic acids

To improve the clinical outcomes of cancer patients, early detection and accurate monitoring of diseases are necessary. Numerous genetic and epigenetic alterations contribute to oncogenesis and cancer progression, and analyses of these changes have been increasingly utilized for diagnostic, prognostic and therapeutic purposes in malignant diseases including gastric cancer (GC). Surgical and/or biopsy specimens are generally used to understand the tumor-associated alterations; however, those approaches cannot always be performed because of their invasive characteristics and may fail to reflect current tumor dynamics and drug sensitivities, which may change during the therapeutic process. Therefore, the importance of developing a non-invasive biomarker with the ability to monitor real-time tumor dynamics should be emphasized. This concept, so called “liquid biopsy”, would provide an ideal therapeutic strategy for an individual cancer patient and would facilitate the development of “tailor-made” cancer management programs. In the blood of cancer patients, the presence and potent utilities of circulating tumor cells (CTCs) and cell-free nucleic acids (cfNAs) such as DNA, mRNA and microRNA have been recognized, and their clinical relevance is attracting considerable attention. In this review, we discuss recent developments in this research field as well as the relevance and future perspectives of CTCs and cfNAs in cancer patients, especially focusing on GC.

Clinical significance of circulating tumor cells in peripheral blood from patients with gastric cancer

BACKGROUND

The authors hypothesized that circulating tumor cells (CTCs) in patients with gastric cancer are associated with prognosis and disease recurrence. In this study, they evaluated CTCs in gastric cancer and clarified the clinical impact of CTCs.

METHODS

In total, 265 consecutive patients with gastric cancer were enrolled. Fourteen patients were excluded from the analysis, including 12 patients who another cancer and 2 patients who refused the treatment. The remaining 251 patients were divided into 2 groups: 148 patients who underwent gastrectomy (the resection group) and 103 patients who did not undergo gastrectomy (the nonresectable group). Peripheral blood samples were collected before gastrectomy or chemotherapy. A proprietary test for capturing, identifying, and counting CTCs in blood was used for the isolation and enumeration of CTCs.

RESULTS

CTCs were detected in 16 patients (10.8%) from the resection group and in 62 patients (60.2%) from the nonresectable group. The overall survival rate for the entire cohort was significantly lower in patients with CTCs than in those without CTCs (P < .0001). In the resection group, relapse-free and overall survival in patients with CTCs was significantly lower than in patients without CTCs (P < .0001). It was noteworthy that the expression of CTCs was an independent factor for determining the overall survival of patients with gastric cancer in multivariate analysis (P = .024). In the nonresectable group, the overall survival rate was significantly lower in patients with CTCs than in those without CTCs (P = .0044).

CONCLUSIONS

The evaluation of CTCs in peripheral blood may be a useful tool for predicting tumor progression, prognosis, and the effect of chemotherapy in patients with gastric cancer.

Multiplex RT-PCR-based detections of CEA, CK20 and EGFR in colorectal cancer patients

AIM: To develop a multiplex reverse transcription polymerase chain reaction (RT-PCR) method detecting circulating tumor cells in the peripheral blood of colorectal cancer (CRC) patients.

METHODS: Peripheral blood samples were collected from 88 CRC patients and 40 healthy individuals from the blood donors’ clinic and subsequently analyzed by multiplex RT-RCR for the expression of carcinoembryonic antigen (CEA), cytokeratin 20 (CK20) and epidermal growth factor receptor (EGFR) mRNA. The analysis involved determining the detection rates of CEA, CK20 and EGFR transcripts vs disease stage and overall survival. Median follow-up period was 19 mo (range 8-28 mo).

RESULTS: Rates of CEA, CK20 and EGFR detection in CRC patients were 95.5%, 78.4% and 19.3%, respectively. CEA transcripts were detected in 3 healthy volunteer samples (7.5%), whereas all control samples were tested negative for CK20 and EGFR transcripts. The increasing number of positive detections for CEA, CK20 and EGFR transcripts in each blood sample was positively correlated with Astler-Coller disease stage (P < 0.001) and preoperative serum levels of CEA (P = 0.029) in CRC patients. Data analysis using Kaplan-Meier estimator documented significant differences in the overall survival of the different CRC patient groups as formed according to the increasing number of positivity for CEA, CK20 and EGFR transcripts.

CONCLUSION: These data suggest that multiplex RT-PCR assay can provide useful information concerning disease stage and overall survival of CRC patients.

Epithelial molecular markers in the peripheral blood of patients with colorectal cancer

Despite the modest improvements in patient survival from colorectal cancer in the last few decades, the overall five-year survival rate remains at 40 to 45 percent. Surgical resection is the mainstay of treatment for colorectal cancer; however, nearly one-half of all patients who undergo a potentially curative resection will relapse because of undetected micrometastasis. The fact that the overall survival rate remains poor strongly suggests that the dissemination of these cells occurs early in the disease process and emphasizes the need for finding feasible diagnostic methods with sufficient sensitivity and specificity. The most commonly used technique for the detection of nucleic acid material of disseminated tumor cells is the polymerase chain reaction. We critically review the literature on DNA and messenger ribonucleic acid molecular markers that have been used for the detection of circulating tumor cells in the peripheral blood of patients with colorectal cancer and other solid tumors as appropriate for comparison. The cytokeratins, particularly cytokeratin 19 and cytokeratin 20, are the most investigated prognostic markers, but even for these questions remain about their clinical value, and hence most recent studies are utilizing a combination of factors. There is an urgent need for standardized isolation and analysis techniques to be adopted thus allowing large-scale, appropriately controlled, multicenter trials to be undertaken on the most promising candidate markers.

Development of a high-throughput membrane-array method for molecular diagnosis of circulating tumor cells in patients with gastric cancers

Recently several noninvasive methods have been employed to detect circulating tumor cells (CTCs) in cancer patients. In this study, we have developed a highly sensitive, high-throughput colorimetric membrane-array method that was designed to detect a panel of mRNA markers including human telomerase reverse transcriptase (hTERT), cytrokeratin-19 (CK-19), carcinoembryonic antigen (CEA) and mucin 1 (MUC1) mRNA for the presence of CTCs in the peripheral blood of patients with gastric cancer (GC). Digoxigenin-labeled cDNA targets synthesized following total RNA isolation from peripheral blood samples of 64 GC patients and 80 healthy individuals were subjected to membrane-array hybridization. The results showed that membrane array could positively detect 5 cancer cells/ml of peripheral blood in GC cell-dilution experiments. The sensitivity, specificity and diagnostic accuracy for hTERT, CK-19, CEA and MUC1 mRNA ranged from 78.1% to 82.8%, 76.3% to 85% and 81.3% to 83.3%, respectively. Both CEA and MUC1 mRNA expression was correlated significantly with all malignant biological properties of GC, such as macroscopic type, depth of tumor invasion, lymph-node metastasis, TNM stage and coexisting distant metastasis (all p < 0.05). Using these 4 markers in combination, the sensitivity, specificity and diagnostic accuracy of membrane array were raised to 89.1%, 91.3% and 90.3%, respectively. The expression of all 4 mRNA markers was an independent predictor for postoperative recurrence/metastasis. GC patients with the expression of all the 4 mRNA markers showed a poorer survival rate than those without the expression of any 1 mRNA marker (p = 0.0223). These findings demonstrated that our membrane-array method could detect CTCs in the circulation of GC patients with considerably high sensitivity and specificity. The identification of CTCs in the peripheral blood may be useful in the auxiliary cancer diagnostics or postoperative surveillance of GC patients for recurrence/metastasis.

Follow-up study of peripheral blood carcinoembryonic antigen mRNA using reverse transcription-polymerase chain reaction as an early marker of clinical recurrence in patients with curatively resected gastric cancer

In this study, we evaluated the clinical significance of detecting carcinoembryonic antigen (CEA) mRNA in the peripheral blood samples of patients with gastric cancer. We analyzed the peripheral blood of 46 patients with gastric cancer who had undergone curative resection. The presence of CEA mRNA was serially monitored using a CEA-specific reverse transcription-polymerase chain reaction (RT-PCR) every 2 months. The clinical recurrence rates according to category were as follows: 100% (3 of 3) in the positive conversion, 0% (0 of 18) in the negative conversion, 50% (3 of 6) in the always-positive, and 10.5% (2 of 19) in the always-negative category. The recurrence rate was 66.7% (6 of 9) in the positive group and 5.4% (2 of 37) in the negative group (P < or =0.00022). Multiple logistic regression analysis demonstrated that only group variable had a significant effect on clinical recurrence (P = 0.015). We conclude that RT-PCR analysis of CEA mRNA in the peripheral blood seems to be a promising tool for the early detection of micrometastatic circulating tumor cells in gastric carcinoma patients and that it can be useful used to identify patients at risk for recurring.

Molecular monitoring of organ recipients from cancer-affected donors by detection of circulating tumor cells

We have initiated regular molecular monitoring based on nested RT-PCR detection of circulating tumor cells for monitoring recipients of organs from cancer-affected donors in Italy (in the context of a "Donation Safety and Donated Organ Quality" project organized by the Centro Nazionale Trapianti). Five patients are being monitored. For two patients who each received a kidney from a single donor with prostate adenocarcinoma, RT-PCR was performed using PSA mRNA. For three recipients of organs (two livers and one kidney) from donors with renal cell carcinoma, RT-PCR was performed using cytokeratine 18 and 19 mRNA. Blood samples from five healthy subjects were used as negative controls. After a median monitoring time of 26 months (range 8 to 32), none of the regular 3-month assays has tested positive. This pilot study suggests that detection of circulating tumor cells by nested RT-PCR may provide a feasible molecular monitoring, which might assist decision making regarding other forms of clinical surveillance.

Detection of circulating tumor cells and of tumor DNA in plasma during tumor progression in rats

The role and clinical significance of circulating tumor cells and of tumor DNA in the plasma have not yet been clarified. In the present study, we compared rates of detection of tumor-derived DNA in the buffy coat to those in plasma from tumor-bearing rats, and we attempted to correlate these rates with the progression of tumors. We injected DHD/K12-PROb cancer cells subcutaneously into BD-IX rats and divided the animals into six groups according to the time between the injection of tumor cells and euthanasia. After euthanasia, macroscopic metastases were assessed and samples of blood and lung were collected. We used mutant allele-specific amplification by PCR to detect tumor-derived DNA. We detected tumor DNA in lung samples from the first week after inoculation, in plasma from the third week and in the buffy coat from the fifth week. All animals analyzed on the 11th week had macro- or micrometastases in their lungs. Regardless of group, the rate of PCR-positive plasma samples was significantly higher than that of circulating tumor cells (P=0.005). In animals with metastases, this difference was also statistically significant (P=0.008). However, neither the detection of tumor DNA in the plasma nor the presence of circulating tumor cells was strongly correlated with the presence of metastases. Thus, cell-free tumor DNA was detected sooner and more frequently than circulating tumor cells and the dissemination of tumor DNA in the plasma seems to be much more common than detectable hematogenic tumor cells during the spread of colorectal cancer.

Clinical significance of circulating tumor cells in blood by molecular detection and tumor markers in esophageal cancer

BACKGROUND

The clinical significance of circulating tumor cells in the blood during surgery has not been elucidated in esophageal squamous cell carcinoma (ESCC). We evaluated the relationship between circulating tumor cells and clinicopathologic findings, compared with that of serum squamous cell carcinoma (SCC) antigen and carcinoembryonic antigen (CEA), in ESCC.

METHODS

Blood samples from 54 consecutive patients were obtained from the peripheral artery and the superior vena cava at three points in time: immediately before surgery, and before and after tumor resection. CEA-specific reverse transcriptase-polymerase chain reaction (RT-PCR), which can quantify circulating tumor cells in blood, was performed. The preoperative values of serum SCC antigen and CEA were also obtained for all patients.

RESULTS

CEA messenger RNA (CEA mRNA) was detected in the blood of 31 out of 54 patients (57.4%). CEA mRNA positivity was detected most frequently after tumor resection and correlated with nodal status and stage grouping. The incidence of total recurrence and blood-borne recurrence was significantly greater in patients with CEA mRNA positivity than in those with CEA mRNA negativity (P =.036 and.0026, respectively). Preoperative serum levels of SCC antigen and CEA did not correlate with clinicopathologic findings and tumor recurrence.

CONCLUSIONS

CEA mRNA detected by RT-PCR was more predictive of tumor recurrence than serum tumor markers. Effective adjuvant therapy is recommended for patients with CEA mRNA positive expression.

A novel method for monitoring response to chemotherapy based on the detection of circulating cancer cells: a case report

We describe a novel method for detecting micrometastasis in the blood stream of cancer patients based on RT-PCR amplification of tumor-associated carcinoembryonic antigen (CEA) mRNA. To increase sensitivity and specificity of RT-PCR, CEA transcript was selectively up-regulated in cancer cells by exposure of peripheral blood to non-toxic concentrations of staurosporine (ST). Thereafter, polyA(+) RNA was extracted from tumor cells captured by means of magnetic beads coated with a monoclonal antibody against a common human epithelial antigen. Finally, RNA was subjected to RT-PCR analysis of CEA transcript. Using this approach, we demonstrated an ST-mediated increase in CEA transcript in blood specimens collected from a patient with metastatic colon cancer before receiving treatment with 5-fluorouracil/leucovorin. After a few cycles of chemotherapy, CEA-positive tumor cells were no longer detected. Clinical follow-up of this patient indicated that treatment with chemotherapy induced a dramatic reduction in liver metastasis. Therefore, it can be hypothesized that lack of CEA transcript detection might be consistent with disappearance or at least marked reduction of circulating tumor cells.