Prognostic role of circulating tumor cells in patients with pancreatic cancer: a meta-analysis

Identification and characterization of tumor and stromal derived liquid biopsy analytes in pancreatic ductal adenocarcinoma

BACKGROUND

The lack of predictive biomarkers contributes notably to the poor outcomes of patients with pancreatic ductal adenocarcinoma (PDAC). Cancer-associated fibroblasts (CAFs) are the key components of the prominent PDAC stroma. Data on clinical relevance of CAFs entering the bloodstream, known as circulating CAFs (cCAFs) are scarce. Here, we developed a combined liquid biopsy assay to detect cCAFs and circulating tumor cells (CTCs) in metastatic PDAC (mPDAC) and other metastatic gastrointestinal malignancies (mGI). In addition, we evaluated plasma hyaluronan (HA) levels as a complementary surrogate biomarker of the stromal extent in patients with PDAC.

METHODS

A sequential liquid biopsy assay based on a two step-enrichment, combining marker dependent and independent cell enrichment, was established for cCAF and CTC detection and validated in mPDAC and mGI patients. The enriched cells were identified by multiplex immunofluorescence. HA measurement was performed by ELISA on blood samples from healthy blood donors (HD), localized and late-stage PDAC patients.

RESULTS

cCAFs (≥ 1cCAFs/7.5 mL blood) were detected in 95.4% of mPDAC and in 78.2% of mGI patients, with significantly higher numbers in mPDAC compared to mGI patients (mean number 22.7 vs. 11.0; P = 0.0318). mPDAC patients with ≥ 15 cCAFs/7.5 mL blood had a significant shorter median overall survival (mOS 3.2 months (95% confidence interval (CI) 0.801-5.855) vs. 14.2 months (95% CI 6.055-22.332); P = 0.013), whereby CTC levels were not associated with mOS. In mGI neither cCAFs nor CTCs had a significant impact on OS. HA plasma levels in mPDAC patients were significantly higher compared to HD (mean 123.0 ng/mL vs. 74.45 ng/mL, P = 0.015). High HA in localized and late-stage PDAC were associated with a significantly shorter mOS (mOSlocalized PDAC: 12.6 months vs. 23.5 months (P = 0.008); mOSmPDAC: 1.8 months vs. 5.3 months (P = 0.004)).

CONCLUSIONS

Our liquid biopsy assay provides robust detection of cCAFs in mPDAC and mGI patients. The measurement of both circulatory stromal parameters, cCAFs and HA, adds valuable clinical information as they are associated with an unfavorable outcome in PDAC. These results highlight that stromal characteristics unique to PDAC could be leveraged to fill the current gap in discovering predictive biomarkers.

A Delay in Adjuvant Therapy Is Associated With Worse Prognosis Only in Patients With Transitional Circulating Tumor Cells After Resection of Pancreatic Ductal Adenocarcinoma

OBJECTIVES

The aim of the study was to assess the association of circulating tumor cells (CTCs) with survival as a biomarker in pancreatic ductal adenocarcinoma (PDAC) within the context of a delay in the initiation of adjuvant therapy.

BACKGROUND

Outcomes in patients with PDAC remain poor and are driven by aggressive systemic disease. Although systemic therapies improve survival in resected patients, factors such as a delay in the initiation of adjuvant therapy are associated with worse outcomes. CTCs have previously been shown to be predictive of survival.

METHODS

A retrospective study was performed on PDAC patients enrolled in the prospective CircuLating tUmor cellS in pancreaTic cancER trial (NCT02974764) on CTC-dynamics at the Johns Hopkins Hospital. CTCs were isolated based on size (isolation by size of epithelial tumor cells; Rarecells) and counted and characterized by subtype using immunofluorescence. The preoperative and postoperative blood samples were used to identify 2 CTC types: epithelial CTCs (eCTCs), expressing pancytokeratin, and transitional CTCs (trCTCs), expressing both pancytokeratin and vimentin. Patients who received adjuvant therapy were compared with those who did not. A delay in the receipt of adjuvant therapy was defined as the initiation of therapy ≥8 weeks after surgical resection. Clinicopathologic features, CTCs characteristics, and outcomes were analyzed.

RESULTS

Of 101 patients included in the study, 43 (42.5%) experienced a delay in initiation and 20 (19.8%) did not receive adjuvant therapy. On multivariable analysis, the presence of trCTCs ( P =0.002) and the absence of adjuvant therapy ( P =0.032) were associated with worse recurrence-free survival (RFS). Postoperative trCTC were associated with poorer RFS, both in patients with a delay in initiation (12.4 vs 17.9 mo, P =0.004) or no administration of adjuvant chemotherapy (3.4 vs NR, P =0.016). However, it was not associated with RFS in patients with timely initiation of adjuvant chemotherapy ( P =0.293).

CONCLUSIONS

Postoperative trCTCs positivity is associated with poorer RFS only in patients who either experience a delay in initiation or no receipt of adjuvant therapy. This study suggests that a delay in the initiation of adjuvant therapy could potentially provide residual systemic disease (trCTCs) a window of opportunity to recover from the surgical insult. Future studies are required to validate these findings and explore the underlying mechanisms involved.

Circulating Cancer Associated Macrophage-like Cells as a Potential New Prognostic Marker in Pancreatic Ductal Adenocarcinoma

BACKGROUND

Circulating Cancer Associated Macrophage-like cells (CAMLs) have been described as novel liquid biopsy analytes and unfavorable prognostic markers in some tumor entities, with scarce data for Pancreatic Ductal Adenocarcinomas (PDAC).

METHODS

Baseline and follow-up blood was drawn from resected curative (n = 36) and palliative (n = 19) PDAC patients. A microfluidic size-based cell enrichment approach (Parsortix^TM) was used for CAML detection, followed by immunofluorescence staining using pan-keratin, CD14, and CD45 antibodies to differentiate between CAMLs, circulating tumor cells (CTCs), and leukocytes.

RESULTS

CAMLs were detectable at baseline in 36.1% of resected patients and 47.4% of palliative PDAC patients. CAML detection was tumor stage independent. Follow-up data indicated that detection of CAMLs (in 45.5% of curative patients) was an independent prognostic factor for shorter recurrence-free survival (RFS) (HR: 4.3, p = 0.023). Furthermore, a combined analysis with CTCs showed the detectability of at least one of these cell populations in 68.2% of resected patients at follow-up. The combined detection of CAMLs and CTCs was also significantly associated with short RFS (HR: 8.7, p = 0.003).

CONCLUSIONS

This pilot study shows that detection of CAMLs in PDAC patients can provide prognostic information, either alone or even more pronounced in combination with CTCs, which indicates the power of liquid biopsy marker analyses.

Sequential Method for Analysis of CTCs and Exosomes from the Same Sample of Patient Blood

Circulating tumor cells (CTCs) and exosomes, both released from the primary tumor into peripheral blood, are a promising source of cancer biomarkers. They are detectable in the blood and carry a large diversity of biological molecules, which can be used for the diagnosis and monitoring of minimally invasive cancers. However, due to their intrinsic differences in counts, size, and molecular contents, studies have focused on only one type of vesicle. Herein, we have developed an integrated system to sequentially isolate CTCs and exosomes from a single patient blood sample for further profiling and analysis. The CTCs are isolated using a commercial filtration method and then the remaining blood is processed using multiple cycles of ultracentrifugation to isolate the exosomes. The method uses two available technologies where the eluent from CTC isolation is usually discarded and interfaces them, so that the eluent can be interfaced to exosome isolation methods. The CTCs are identified based on fluorescence staining of their surface markers, while the exosomes are analyzed using transmission electron microscopy, nanosight tracking analysis, and mass spec proteomic analysis. This analysis showed CTCs detected by their surface markers for metastatic hepatocellular carcinoma (HCC), while essentially none were detected for cirrhosis. The exosome analysis resulted in the identification of ∼500-1000 exosome proteins per sample confirmed by detection of exosome surface markers CD9, CD63, CD81, and TSG101 in addition to proteins related to cancer progression. Proteins enriched in HCC exosomes were shown to be involved in the immune response, metastasis, and proliferation.

Characterization of RARRES1 Expression on Circulating Tumor Cells as Unfavorable Prognostic Marker in Resected Pancreatic Ductal Adenocarcinoma Patients

Simple Summary

Our explorative study used a microfluidic-based approach for circulating tumor cell (CTC) detection in 55 pancreatic ductal adenocarcinoma (PDAC) patients before treatment initiation (baseline) and during follow-up (FUP). For the first time, we assessed the expression of retinoic acid receptor responder 1 (RARRES1) on CTCs. CTCs were detected in 25.5% of patients at baseline, while the detection rate during FUP was higher (45.5%). Especially high CTC counts during FUP in resected patients were associated with early tumor relapse (p = 0.02). Combining CTC detection and RARRES1 protein expression showed that RARRES1-positive patients with high CTCs counts after curative operation during FUP had a worse prognosis (p = 0.001). In conclusion, RARRES1 is a new marker of interest for further research investigations on subtypes of CTCs in PDAC.

Abstract

Background: In pancreatic ductal adenocarcinoma (PDAC), the characterization of circulating tumor cells (CTCs) opens new insights into cancer metastasis as the leading cause of cancer-related death. Here, we focused on the expression of retinoic acid receptor responder 1 (RARRES1) on CTCs as a novel marker for treatment failure and early relapse. Methods: The stable isotope labeling of amino acids in cell culture (SILAC)—approach was applied for identifying and quantifying new biomarker proteins in PDAC cell lines HPDE and its chemoresistant counterpart, L3.6pl-Res. Fifty-five baseline and 36 follow-up (FUP) peripheral blood samples were processed via a marker-independent microfluidic-based CTC detection approach using RARRES1 as an additional marker. Results: SILAC-based proteomics identified RARRES1 as an abundantly expressed protein in more aggressive chemoresistant PDAC cells. At baseline, CTCs were detected in 25.5% of all PDAC patients, while FUP analysis (median: 11 months FUP) showed CTC detection in 45.5% of the resected patients. CTC positivity (≥3 CTC) at FUP was significantly associated with short recurrence-free survival (p = 0.002). Furthermore, detection of RARRES1 positive CTCs was indicative of an even earlier relapse after surgery (p = 0.001). Conclusions: CTC detection in resected PDAC patients during FUP is associated with a worse prognosis, and RARRES1 expression might identify an aggressive subtype of CTCs that deserves further investigation.

Tumor-Stroma Interaction in PDAC as a New Approach for Liquid Biopsy and its Potential Clinical Implications

The extremely poor prognosis for patients with pancreatic ductal adenocarcinoma (PDAC) has remained unchanged for decades. As a hallmark of PDAC histology, the distinct desmoplastic response in the tumor microenvironment is considered a key factor exerting pro- and antitumor effects. Increasing emphasis has been placed on cancer-associated fibroblasts (CAFs), whose heterogeneity and functional diversity is reflected in the numerous subtypes. The myofibroblastic CAFs (myCAFs), inflammatory CAFs (iCAFs) and antigen presenting CAFs (apCAFs) are functionally divergent CAF subtypes with tumor promoting as well as repressing effects. Precise knowledge of the underlying interactions is the basis for a variety of treatment approaches, which are subsumed under the term antistromal therapy. Clinical implementation is still pending due to the lack of benefit-as well as paradoxical preclinical findings. While the prominent significance of CAFs in the immediate environment of the tumor is becoming clear, less is known about the circulating (c)CAFs. cCAFs are of particular interest as they seem not only to be potential new liquid biopsy biomarkers but also to support the survival of circulating tumor cells (CTC) in the bloodstream. In PDAC, CTCs correlate with an unfavorable outcome and can also be employed to monitor treatment response, but the current clinical relevance is limited. In this review, we discuss CTCs, cCAFs, secretomes that include EVs or fragments of collagen turnover as liquid biopsy biomarkers, and clinical approaches to target tumor stroma in PDAC.

Circulating Tumor Cells, Circulating Tumor DNA and Other Blood-based Prognostic Scores in Pancreatic Ductal Adenocarcinoma - Mini-Review

Pancreatic ductal adenocarcinoma represents a disease with increasing incidence. Its prognosis is the worst among all malignancies despite the aggressive combined multimodal treatment across all stages. In metastatic disease, median survival is approximatelly one year. The mainstay of treatment is chemotherapy (neo/adjuvant, palliative) and in selected subgroups of patients even radiotherapy. Nevertheless, nowadays there are very few prognostic and/or predictive biomarkers available that can be used to identify and better stratify patients based on risk to tailored treatment. Potentially, promising areas of research are circulating tumor cells and circulating tumor DNA, which can be easily obtained from peripheral blood - so called liquid biopsy. They may serve as a tool to assess response to applied treatment, and to detect the emergence of treatment-resistant clones or early disease relapse. Moreover, their study may allow identification of potentially tumor-specific alterations, which may serve as target structures for targeted (tailored) therapy. Alternatively, different prognostic indexes/scores calculated by analysis of selected parameters of blood and/or biochemistry can be used to better stratify patients based on risk and better predict prognosis. The aim of this mini-review is to provide a basic overview of the current state of the art in this area and its potential significance for clinical practice.

Perioperative Predictors of Early Recurrence for Resectable and Borderline-Resectable Pancreatic Cancer

Simple Summary

Most patients with a pancreatic ductal adenocarcinoma develop a recurrence after surgery. Predictive factors may therefore guide therapeutic decision-making. We aimed to identify perioperative predictors of the early recurrence of pancreatic ductal adenocarcinomas. We found that preoperative (>52 U/mL) and postoperative (>37 U/mL) elevated carbohydrate antigen 19-9 levels as well as a tumor size >3.0 cm were independently associated with an early recurrence after a pancreatectomy. Furthermore, an early recurrence resulted in a more frequent liver metastasis than a late recurrence, suggesting that patients experiencing a recurrence within 12 months had undetectable micrometastases. Further studies are needed to identify new biomarkers for the detection of clinically occult micrometastases during surgery as current preoperative risk factors are inadequate to accurately identify patients susceptible to an early recurrence of pancreatic ductal adenocarcinomas.

Abstract

We aimed to identify the perioperative predictors of the early recurrence (ER) of resectable and borderline-resectable pancreatic ductal adenocarcinomas (PDACs). After surgery for a PDAC, most patients develop a recurrence. Predictive factors may therefore guide therapeutic decision-making. Patients (n = 234) who underwent a pancreatectomy for a PDAC between 2006 and 2019 were included. The postrecurrence survival (PRS) was estimated using Kaplan–Meier curves. Predictive factors for an ER were assessed using logistic regression analyses; 93 patients (39.7%) were recurrence-free at the last follow-up. Patients with an ER (n = 85, 36.3%), defined as a recurrence within the first 12 months after surgery, had 1- and 2-year PRS rates of 38.7% and 9.5%, respectively, compared with 66.9% and 37.2% for those with a late recurrence (n = 56, 23.9%; both p < 0.001). The most common site of an ER was the liver (55.3%) with a significantly shorter median overall survival time than that with either a local or a lung recurrence (14.5 months; p < 0.001). Preoperative and postoperative risk factors for an ER included a tumor size >3.0 cm (odds ratio (OR): 3.11, 95% confidence interval (CI): 1.35–7.14) and preoperative carbohydrate antigen 19-9 (CA19-9) levels >52 U/mL (OR: 3.25, 95% CI: 1.67–6.30) and a pathological tumor size >3.0 cm (OR: 2.00, 95% CI: 1.03–3.90) and postoperative carbohydrate antigen 19-9 levels >37 U/mL (OR: 2.11, 95% CI: 1.02–4.36), respectively. Preoperatively (>52 U/mL) and postoperatively (>37 U/mL) elevated CA19-9 and a tumor size >3.0 cm were independent predictors for an ER after a pancreatectomy for a PDAC.

The importance of circulating and disseminated tumor cells in pancreatic cancer

Pancreatic cancer is a lethal disease in a large part due to the systemic nature at the time of diagnosis. In those patients who undergo a potentially curative resection of pancreatic cancer, the overwhelming majority will have systemic relapse. Circulating tumor cells are an important mediator of the development of metastases. Circulating tumor cells have been identified in patients with clinically localized resectable pancreatic cancer and exist as several phenotypes. Mesenchymal and stem cell-like phenotypes of circulating tumor cells predict early recurrence and worse survival. This review focuses on the current understanding of circulating tumor cells in pancreatic cancer and how this information can be used in developing more effective therapy in the future.

Circulating Tumor Cells: Overview and Opportunities in Cytology

Circulating tumor cells (CTCs) have long been assumed to be the substrate of cancer metastasis. However, only in recent years have we begun to leverage the potential of CTCs found in minimally invasive peripheral blood specimens to improve care for cancer patients. Currently, CTC enumeration is an accepted prognostic indicator for breast, prostate, and colorectal cancer; however, CTC enumeration remains largely a research tool. More recently, the focus has shifted to CTC characterization and isolation which holds great promise for predictive testing. This review summarizes the relevant clinical, biological, and technical background necessary for pathologists and cytopathologists to appreciate the potential of CTC techniques. A summary of relevant systematic reviews of CTCs for specific cancers is then presented, as well as potential applications to precision medicine. Finally, we suggest future applications of CTC technologies that can be easily incorporated in the pathology laboratory, with the recommendation that pathologists and particularly cytopathologists apply these technologies to small specimens in the era of "doing more with less."

Phase Ib trial combining capecitabine, erlotinib and bevacizumab in pancreatic adenocarcinoma - REBECA trial

Background Purpose of this phase Ib trial was to establish the maximum tolerable dose (MTD) of capecitabine and to escalate the dosages of erlotinib and bevacizumab to determine the recommended phase II dose (RP2D) in patients with advanced/metastatic pancreatic adenocarcinoma not pretreated for metastatic disease. Methods Starting doses were capecitabine 500 mg/m² bid orally continuously, erlotinib 100 mg orally daily, and bevacizumab 5 mg/kg intravenously q 2 weeks. Dose escalation was performed according to a 3 + 3 design for capecitabine until MTD, for erlotinib and bevacizumab until the maximum doses registered by applying a substance-related, toxicity-based scheme accompanied by pharmacokinetic analysis. Circulating tumor cells (CTCs) were determined pretherapeutically by immunohistochemical identification after enrichment with immunomagnetic separation. Results Thirty patients were evaluable at six dose levels. 900 mg/m² bid were determined as MTD for capecitabine based on dose-limiting toxicities: cutaneous in two patients and vascular in another. The most severe (Grade (G)3/4) drug-related treatment-emergent adverse events (toxicities) belonged to the categories gastrointestinal, vascular, cutaneous, cardiovascular, metabolic/nutritional or hematological. G3 toxicities occurred in 14 (47%), G3 + G4 in a single (3%) patient. 2 out of 28 patients (7%) exerted partial response, 17 (61%) stable disease. Pharmacokinetic evaluation revealed lack of drug-drug interaction between capecitabine and erlotinib and their metabolites. Presence of CTCs was associated with shorter progression-free survival (p = 0.009). Conclusions The study met the primary objective. RP2D was capecitabine 800 mg/m² bid continuously, erlotinib 150 mg daily, and bevacizumab 10 mg/kg q 2 weeks. The regimen could be applied safely, but demonstrated limited efficacy.

A novel messenger RNA signature as a prognostic biomarker for predicting relapse in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) death rate and recurrence rate have remained obstinately high. Current methods can not satisfy the need of predicting cancer relapse accurately. Utilizing expression profiles of 10 GEO datasets (N = 774), we identified 154 differentially expressed genes (DEGs) between PDAC and normal pancreas tissue or paracancerous tissue. Next we built a 16-mRNA-based signature by means of the LASSO COX regression model. We also validated the prognostic value of the signature. Patients were classified into high-risk and low-risk group according to the signature risk score; 1 year RFS was 45% (95% CI: 31.6%–63.9%) for high-risk group in contrast to 92.5% (95% CI: 86.3%–99.1%) for low-risk group. Moreover, it could predict RFS well in cases with the receipt of different treatment modalities. The 16-mRNA-based signature was an independent and powerful prognostic biomarker for RFS for PDAC patients (HR = 7.74, 95% CI: 3.25–18.45, p < 0.0001).

Circulating and disseminated tumor cells in pancreatic cancer and their role in patient prognosis: a systematic review and meta-analysis

Background

Disseminated tumor cells (DTCs) and circulating tumor cells (CTCs) have been postulated to seed metastases and contribute to poorer patient outcomes in many types of solid cancer. To date, no systematic reviews have examined the role of both DTCs and CTCs in pancreatic cancer. We aimed to determine the prognostic value of DTCs/CTCs in pancreatic cancer using a systematic review and meta-analysis.

Materials and Methods

A comprehensive literature search identified studies examining DTCs and CTCs in the bone marrow and blood of pancreatic cancer patients at diagnosis with follow-up to determine disease-free/progression-free survival (DFS/PFS) and overall survival (OS). Statistical analyses were performed to determine the hazard ratio (HR) of DTCs/CTCs on DFS/PFS and OS.

Results

The literature search identified 16 articles meeting the inclusion criteria. The meta-analysis demonstrated statistically significant HR differences in DFS/PFS (HR = 1.93, 95% CI 1.19–3.11, P = 0.007) and OS (HR = 1.84, 95% CI 1.37–2.45, P =< 0.0001), indicating patients with detectable DTCs/CTCs at diagnosis have worse prognoses. Subgroup analyses suggested CTCs in the peripheral blood (HR =2.03) were more indicative of poor OS prognosis than DTCs in the bone marrow (HR = 1.91), although the difference between these was not statistically significant. Positivity of the CellSearch detection method for DTC/CTC had the highest correlation with decreased OS (HR = 2.79) while immunodetection (HR = 1.91) and RT-PCR (HR = 1.25) were less effective in determining prognosis.

Conclusion

The detection of DTCs/CTCs at diagnosis is associated with poorer DFS/PFS and OS in pancreatic cancer.

Liquid Biopsy for Cancer: Circulating Tumor Cells, Circulating Free DNA or Exosomes?

Precision medicine and personalized medicine are based on the development of biomarkers, and liquid biopsy has been reported to be able to detect biomarkers that carry information on tumor development and progression. Compared with traditional 'solid biopsy', which cannot always be performed to determine tumor dynamics, liquid biopsy has notable advantages in that it is a noninvasive modality that can provide diagnostic and prognostic information prior to treatment, during treatment and during progression. In this review, we describe the source, characteristics, technology for detection and current situation of circulating tumor cells, circulating free DNA and exosomes used for diagnosis, recurrence monitoring, prognosis assessment and medication planning.

Pancreatic cancer: Are "liquid biopsies" ready for prime-time?

Pancreatic cancer is a disease that carries a poor prognosis. Accurate tissue diagnosis is required. Tumours contain a high content of stromal tissue and therefore biopsies may be inconclusive. Circulating tumour cells (CTCs) have been investigated as a potential “liquid biopsy” in several malignancies and have proven to be of prognostic value in breast, prostate and colorectal cancers. They have been detected in patients with localised and metastatic pancreatic cancer with sensitivities ranging from 38%-100% using a variety of platforms. Circulating tumour DNA (ctDNA) has also been detected in pancreas cancer with a sensitivity ranging from 26%-100% in studies across different platforms and using different genetic markers. However, there is no clear consensus on which platform is the most effective for detection, nor which genetic markers are the most useful to use. Potential roles of liquid biopsies include diagnosis, screening, guiding therapies and prognosis. The presence of CTCs or ctDNA has been shown to be of prognostic value both at diagnosis and after treatment in patients with pancreatic cancer. However, more prospective studies are required before this promising technology is ready for adoption into routine clinical practice.

Liquid biopsy: will it be the 'magic tool' for monitoring response of solid tumors to anticancer therapies?

PURPOSE OF REVIEW

The aim of this review is to highlight the recent advances (in the past 12 months) concerning circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) in oncology.

RECENT FINDINGS

The value of CTCs as a prognostic biomarker is now well validated in breast, colon, and prostate cancer, but no trial has yet demonstrated that modifying treatment according to CTCs is superior to standard of care. Ongoing trials are addressing the clinical utility of CTCs. Moreover, there is emerging evidence about the potential of CTCs as a tumor tissue source to analyze protein and RNA expression, DNA mutations and drug sensitivity. ctDNA is a specific biomarker associated with tumor burden, and small studies have shown an association with worse outcome; prospective clinical studies on the prognostic and predictive value of ctDNA are needed. ctDNA can be used for tumor molecular profiling, with the potential advantage to encompass the spectrum of mutations present in the tumor.

SUMMARY

CTCs and ctDNA are promising new biomarkers in oncology, with potential clinical applications for monitoring and for comprehensive molecular profiling of cancer. For each assay, demonstration of analytical and clinical validity, as well as clinical utility in prospective clinical trials is needed before implementation in clinical practice.

Prognostic significance of circulating tumor cells in small--cell lung cancer patients: a meta-analysis

Circulating tumor cells (CTCs) are believed to be particularly important and a reliable marker of malignancy. However, the prognostic significance of CTCs detected in patients with small cell lung cancer (SCLC) is still unclear. We therefore aimed to assess the prognostic relevance of CTCs using a meta-analysis. We searched PubMed for relevant studies and statistical analyses were conducted to calculate the hazard ratio (HR) and 95% confidence intervals (CIs) using fixed or random-effect models according to the heterogeneity of included studies. A total of 7 papers covering 440 SCLC patients were combined in the final analysis. The meta-analysis revealed that CTCs were significantly associated with shorter overall survival (HR=1.9; 95%CI: 1.19-3.04; Z=2.67; P<0.0001) and progression-free survival (HR=2.6; 95%CI: 1.9-3.54; Z=6.04; P<0.0001). The results thus suggest that the presence of CTCs indicates a poor prognosis in patients with SCLC. Further well-designed prospective studies are required to explore the clinical applications of CTCs in SCLC.

Circulating Epithelial Cells in Patients with Pancreatic Lesions: Clinical and Pathologic Findings

BACKGROUND

Circulating epithelial cell (CEC) isolation has provided diagnostic and prognostic information for a variety of cancers, previously supporting their identity as circulating tumor cells in the literature. However, we report CEC findings in patients with benign, premalignant, and malignant pancreatic lesions using a size-selective filtration device.

STUDY DESIGN

Peripheral blood samples were drawn from patients found to have pancreatic lesions on preoperative imaging at a surgical clinic. Blood was filtered using ScreenCell devices, which were evaluated microscopically by a pancreatic cytopathologist. Pathologic data and clinical outcomes of these patients were obtained from medical records during a 1-year follow-up period.

RESULTS

Nine healthy volunteers formed the control group and were found to be negative for CECs. There were 179 patients with pancreatic lesions that formed the study cohort. Circulating epithelial cells were morphologically similar in patients with a variety of pancreatic lesions. Specifically, CECs were identified in 51 of 105 pancreatic ductal adenocarcinomas (49%), 7 of 11 neuroendocrine tumors (64%), 13 of 21 intraductal papillary mucinous neoplasms (62%), and 6 of 13 patients with chronic pancreatitis. Rates of CEC identification were similar in patients with benign, premalignant, and malignant lesions (p = 0.41). In addition, CEC findings in pancreatic ductal adenocarcinoma patients were not associated with poor prognosis.

CONCLUSIONS

Although CECs were not identified in healthy volunteers, they were identified in patients with benign, premalignant, and malignant pancreatic lesions. The presence of CECs in patients presenting with pancreatic lesions is neither diagnostic of malignancy nor prognostic for patients with pancreatic ductal adenocarcinoma.

Size and deformability based separation of circulating tumor cells from castrate resistant prostate cancer patients using resettable cell traps

The enumeration and capture of circulating tumor cells (CTCs) are potentially of great clinical value as they offer a non-invasive means to access tumor materials to diagnose disease and monitor treatment efficacy. Conventional immunoenrichment of CTCs may fail to capture cells with low surface antigen expression. Micropore filtration presents a compelling label-free alternative that enriches CTCs using their biophysical rather than biochemical characteristics. However, this strategy is prone to clogging of the filter microstructure, which dramatically reduces the selectivity after processing large numbers of cells. Here, we use the resettable cell trap (RCT) mechanism to separate cells based on their size and deformability using an adjustable aperture that can be periodically cleared to prevent clogging. After separation, the output sample is stained and analyzed using multi-spectral analysis, which provides a more sensitive and unambiguous method to identify CTC biomarkers than traditional immunofluorescence. We tested the RCT device using blood samples obtained from 22 patients with metastatic castrate-resistant prostate cancer while comparing the results with the established CellSearch® system. The RCT mechanism was able to capture ≥5 CTCs in 18/22 (82%) patients with a mean count of 257 in 7.5 ml of whole blood, while the CellSearch system found ≥5 CTCs in 9/22 (41%) patients with a mean count of 25. The ~10× improvement in the CTC capture rate provides significantly more materials for subsequent analysis of these cells such as immunofluorescence, propagation by tissue culture, and genetic profiling.