Technical aspects of minimal residual disease detection in carcinoma patients

Early postoperative magnet resonance tomography after resection of cerebral metastases

BACKGROUND

In contrast to malignant gliomas, the impact of an early postoperative MRI after surgery of cerebral metastasis is still unclear. The present study analyses early MRI-based postoperative resection controls and incidence of in-brain progression in 116 patients suffering from 130 cerebral metastases.

METHODS

The extent of surgical resection was verified by an early postoperative contrast-enhanced 1.5-T MRI within 72 h after surgery of cerebral metastases and correlated with in-brain progression, leptomeningeal carcinomatosis, and progression-free survival.

RESULTS

MRI confirmed complete resection was seen in 80 out of 130 metastases (61.5 %). In 24 metastases (18.5 %), no final decision on degree of resection could be made. Residual tumor was seen in 26 cases (20 %). Local in-brain progression was observed in 40 of 130 (30.8 %) cases. The incidence of in-brain progression significantly correlated with dural contact of the metastasis (p < 0.05) and residual tumor on early postoperative MRI (p < 0.0001). The odds ratio for local recurrence with residual tumor is 8.2-fold compared to no residual tumor.

CONCLUSIONS

Residual tumor after metastasis extirpation was shown in nearly 20 % of patients by an early postoperative MRI and significantly correlated with local in-brain progression. Furthermore, dural contact of cerebral metastases was identified as a risk factor for local recurrence. Further studies are mandatory to clearly identify the incidence of incomplete resections of cerebral metastases and their oncologic impact. An early postoperative MRI after resection of cerebral metastases is recommended as residual tumor promotes local recurrence.

Permissive expansion and homing of adoptively transferred T cells in tumor-bearing hosts

Activated T cells expressing endogenous or transduced TCRs are two cell types currently used in clinical adoptive T-cell therapy. The ability of these cells to recognize their antigen, expand and traffic to the tumor site are the initial steps necessary for successful therapy. In this study, we used in vivo bioluminescent imaging (BLI) of Renilla luciferase (RLuc) expressing T cells to evaluate the ability of adoptively transferred T cells to survive, expand and home to tumor site in vivo. Using this method, termed RT-Rack (Rluc T cell tracking), we followed T-cell response against tumors in vivo. Expansion and homing of adoptively transferred T cells were antigen dependent, but independent of the host immune status. Moreover, we successfully detected T-cell response to small and large tumors, including autochthonous liver tumors. The adoptively transferred T cells were not ignorant or excluded in a partially tolerant host, which expressed low level of the target in the periphery. Using T cell receptor (TCR)-engineered T cells, we showed the ability of these cells to respond in tumor-bearing hosts by expanding and homing to the tumor site. In all these models, the host immune status, the nature of the tumor or of the antigen, the tumor size and the presence of the targeted antigen in the periphery did not prevent the adoptively transferred T cells from responding by expanding and homing to the tumor. However, T cells had higher expression of the inhibitory receptor PD1 and reduced functional activity when a self-antigen was targeted.

Multiplex PCR-based detection of circulating tumor cells in lung cancer patients using CK19, PTHrP, and LUNX specific primers

INTRODUCTION

The aim of this study was to develop a multiplex polymerase chain reaction (PCR)-based method for detection of circulating tumor cells in peripheral blood of lung cancer (LC) patients.

PATIENTS AND METHODS

Peripheral blood was collected from 71 healthy donors and 125 LC patients at different pathological stages. Samples were analyzed using multiplex PCR, and specific primers for CK19, PTHrP, and LUNX mRNA. The sensitivity of our method was set at 10 LC cells (A549 cells) in 3 mL of peripheral blood of healthy donors using spiking experiments.

RESULTS

The detection rates in LC patients for CK19, PTHrP, and LUNX were 45.6%, 64.8%, and 28%, and in healthy individuals were 7%, 7%, and 5.6%, respectively. Overall, our method produced 77.8% positive detections for at least 1 molecular marker. Twenty-eight (22.2%) were negative for expression of all markers, 39 (31.2%) were positive for expression of 1 marker, 42 (33.6%) were positive for expression of 2 markers, and 17 (13.6%) were positive for expression of all 3 markers. Detection of CK19 mRNA expression positively correlated with LC stage and distant metastases. PTHrP mRNA detection correlated positively with LC stage, presence of bone metastasis, and squamous cell carcinoma, and LUNX mRNA detection correlated with lymph node involvement. Combined detection of 2 or 3 markers was significantly correlated with metastatic disease, and negative detection of all 3 molecular markers was correlated with early stage nonmetastatic disease.

CONCLUSION

Multiple PCR-based detection of CK19, PTHrP, and LUNX mRNA expression provides useful information for disease stage and dissemination in LC patients.

Detection of epithelial cells by RT-PCR targeting CEA, CK20, and TEM-8 in colorectal carcinoma patients using OncoQuick density gradient centrifugation system

BACKGROUND

The detection of epithelial-specific mRNA correlates well with the presence of cancer cells in the peripheral blood and provides a rational explanation for subsequent metastasis.

MATERIAL AND METHODS

Forty-two, patients with colorectal cancer and 14 controls were included in our study. Peripheral blood samples were acquired at 24 h before and 48 h after laparotomy. Tissue samples were also acquired from the primary lesion. All samples were examined for the expression profile of CEA, CK20, and TEM-8.

RESULTS

Tissue samples expressed CEA in every specimen, CK20 in 30, and TEM-8 in 41. CEA and CK20 were not identified in the control blood samples while TEM-8 was detected in 4. CEA was detected in 17, CK20 in 28 and TEM-8 in 23, of the preoperative blood samples. CEA mRNA expression in preoperative blood sample and TNM stage were found independently associated with increased tumor size. Positive CEA, CK20, and TEM-8 signals were found in 25, 25, and 23 of the postoperative blood samples respectively.

CONCLUSIONS

CK20 and CEA are significantly more frequently detected in colon cancer patients than in healthy controls and can serve as markers. Cancer cell mRNA is commonly detected in the preoperative and postoperative peripheral blood samples. Tumor size was independently associated with the preoperative detection of CEA mRNA. Although TEM-8 mRNA detection in the peripheral blood showed no specificity for cancer patients or correlation with clinical stage, identification and validation of genes and proteins implicated in metastatic process needs to be further investigated.

Minimal disease monitoring by QRT-PCR: guidelines for identification and systematic validation of molecular markers prior to evaluation in prospective clinical trials

Real-time RT-PCR (QRT-PCR) is a sensitive method for the detection of minimal disease (MD) and may improve monitoring of disease status and stratification of patients for therapy. Where tumour-specific mRNAs have not been identified, the selection of which target(s) is(are) optimal for the detection of MD remains a challenge. This reflects the heterogeneity of tumour cells, the stability of mRNAs and low-level of transcription in cells of the normal haemopoietic compartments. The aim of this study was to establish for the first time guidelines for the systematic prioritization of potential markers of MD detected by QRT-PCR prior to evaluation in multicentre prospective clinical outcome studies. We combined microarray analysis, ESTs gene expression profiles, improved probe-sets sequence annotation, and previously described standard operating procedures for QRT-PCR analysis to identify and prioritize potential markers of MD. Using this methodology, we identified 49 potential markers of MD in neuroblastoma (NB), of which 11 were associated with neuronal function. We found that, in addition to TH, Phox2B and DCX mRNA may be useful targets for the detection of MD in children with NB. This same strategy could be exploited to select MD markers of other solid tumours from the large number of potential targets identified by microarray gene expression profiles.

A validated quantitative assay to detect occult micrometastases by reverse transcriptase-polymerase chain reaction of guanylyl cyclase C in patients with colorectal cancer

PURPOSE

Guanylyl cyclase C (GCC), a receptor for bacterial diarrheagenic enterotoxins, may be a prognostic and predictive marker to detect occult micrometastases in patients undergoing staging for colorectal cancer. However, quantification of GCC expression in tissues by the quantitative reverse transcription-PCR (qRT-PCR) has not undergone analytic and clinicopathologic validation.

EXPERIMENTAL DESIGN

A technique to quantify GCC mRNA in tissues employing RT-PCR was developed and validated employing external calibration standards of RNA complementary to GCC.

RESULTS

GCC qRT-PCR exhibited reaction efficiencies >92%, coefficients of variations <5%, linearity >6 orders of magnitude, and a limit of quantification of >25 copies of GCC cRNA. This assay confirmed that GCC mRNA was overexpressed by colorectal tumors from 41 patients, which correlated with increased GCC protein quantified by immunohistochemistry. Analyses obtained with 164 lymph nodes from patients free of cancer and 15 nodes harboring metastases established a threshold for metastatic disease of approximately 200 GCC mRNA copies/mug total RNA, with a sensitivity of 93% and specificity of 97%. GCC mRNA above that threshold was detected in 76 of 367 (approximately 21%) nodes free of disease by histopathology from 6 of 23 (26%) patients, suggesting the presence of occult micrometastases.

CONCLUSIONS

Quantifying GCC mRNA in tissues by RT-PCR employing external calibration standards is analytically robust and reproducible, with high clinicopathologic sensitivity and specificity. This validated assay is being applied to approximately 10,000 lymph nodes in a prospective trial to define the sensitivity of GCC qRT-PCR for staging patients with colorectal cancer.

Integrating Circulating Tumor Cell Assays into the Management of Breast Cancer

OPINION STATEMENT

Breast cancer is the most frequent type of cancer in women with major cause of death being metastatic disease. Despite aggressive adjuvant systemic therapy with a variety of novel chemotherapeutic and biologic agents recurrence rates vary widely with current conventional prognostic and predictive markers failing to reliably predict recurrence in either node negative (low risk of recurrence) or node positive (considered to have a high risk of recurrence). The ability to detect the presence of minimal residual disease in various body compartments such as the bone marrow, lymph nodes, and peripheral blood represents a viable alternative. Various methods to detect circulating tumor cells (CTCs) have been described including techniques based on polymerase chain reactions (PCR) and cell enrichment methods. Studies have shown that CTCs in metastatic breast cancer can be used as a marker for overall survival and assessment of therapeutic response. The role of CTCs in early stage breast cancer is less well-established. Large prospective trials are needed to further understand its biology and confirm its role as a predictive and prognostic marker before we can incorporate it into the conventional staging system.

The Future in Diagnosis and Staging of Lung Cancer

Lung cancers at the same stage of disease have markedly different rates of disease progression. In this review, we will address current molecular techniques which provide new opportunities according to diagnosis, prediction of survival or selection of therapy. New molecular techniques might be helpful in TNM staging and lead to additional individual prognostic information. A revised TNM system could include a TNM component and a molecular supplemental component allowing new markers to be evaluated without undermining the value of classic TNM staging. Furthermore, molecular techniques might be helpful in the early or differential diagnosis of lung cancer. Since many new targeted agents are effective only if their respective molecular markers are mutated or expressed at sufficient levels, DNA-based or RNA-based techniques have the potential to influence treatment selection in the future. Overall, we can expect that molecular markers will contribute to a more personalized lung cancer treatment.

Nucleic acid quantification and disease outcome prediction in colorectal cancer

Histopathological stage at diagnosis remains the most important prognostic determinant for colorectal cancer. However, conventional staging is unable to predict disease outcome accurately for each individual patient. This results in considerable prognostic heterogeneity within a given tumor stage and is of particular relevance for a subgroup of patients with stage II disease that would benefit from adjuvant therapy. The recent advances in functional genomics are beginning to have a significant impact on clinical oncology, and there is widespread interest in using molecular techniques for clinical applications. These have focused on two approaches: the use of polymerase chain reaction (PCR)-based methods for the detection of occult disease in lymph nodes, bone marrow and blood and the use of microarrays for the expression profiling of primary tumors. The aim is to develop molecular classifiers that will allow the prediction of disease outcome, thus matching patients with individualized treatment. Despite the obvious attractions of these approaches, there have been significant technical, biological and analytical problems in their translation into clinically relevant practice. This is particularly true for colorectal cancer, the second most common cancer in the western world. Nevertheless, progress is being made and the improved awareness and appreciation of those difficulties is beginning to generate results that should prove useful for clinical oncology.

Real-time reverse transcription PCR and the detection of occult disease in colorectal cancer

Molecular diagnostics offers the promise of accurately matching patient with treatment, and a resultant significant effect on improved disease outcome. More specifically, the real-time reverse transcription polymerase chain reaction (qRT-PCR), with its combination of conceptual simplicity and technical utility, has the potential to become a valuable analytical tool for the detection of mRNA targets from tissue biopsies and body fluids. Its potential is particularly promising in cancer patients, both as a prognostic assay and for monitoring response to therapy. Colorectal cancer provides an instructive paradigm for this potential as well as the problems associated with its use as a clinical assay. Currently, histopathological staging, which provides a static description of the anatomical extent of tumour spread within a surgical specimen, defines patient prognosis. The detection of lymph node (LN) metastasis constitutes the most important prognostic factor in colorectal cancer and as the primary indicator of systemic disease spread, LN status determines the choice of postoperative adjuvant chemotherapy. However, its limitations are emphasised by the considerable prognostic heterogeneity of patients within a given tumour stage: not all patients with LN-negative cancers are cured and not all patients with LN-positive tumours die from their disease. This has resulted in a search for more accurate staging protocols and has seen the introduction of the concept of "molecular staging", the incorporation of molecular parameters into clinical tumour staging. Quantification of disease-associated mRNA is one such parameter that utilises the qRT-PCR assay's potential for generating quantitative results. These are not only more informative than qualitative data, but contribute to assay standardisation and quality management. This review provides an assessment of the practical value to the clinician of RT-PCR-based molecular diagnostics. It points out reasons for the many contradictory results encountered in the literature and concludes that there is an urgent need for standardisation at every level, starting with pre-assay sample acquisition and template preparation, assay protocols and post-assay analysis.

Circulating tumor cells: the 'leukemic phase' of solid cancers

It is well known that malignant cells circulate in the bloodstream of patients with solid tumors. However, the biological significance of circulating tumor cells (CTCs) and the clinical relevance of their detection are still debated. Besides technical issues regarding CTC-detection methods, discontinuous shedding of CTCs from established cancer deposits, genomic instability and metastatic inefficiency might underlie the conflicting results currently available. Nevertheless, technological advances and recent clinical findings are prompting researchers to dissect CTC biology further. Here, we review these recent findings, and discuss the prospects for the identification and molecular characterization of the CTC subset that is responsible for metastasis development. This would provide a formidable tool for prognosis evaluation, anticancer-drug development and, ultimately, cancer-therapy personalization.

Detection of disseminated tumour cells in the liver of cancer patients

AIMS

The liver is a common site of metastasis from a variety of solid malignancies. This is due to disseminated tumour cells (DTC) that have spread prior to or during surgery from the primary carcinoma. This article gives a short overview of the data published on the detection of DTC in the liver and describes the commonly used detection methods and respective markers.

METHODS

A literature survey was performed in public medical databases comprising the last 15 years with focus on DTC detection in liver tissue of cancer patients.

KEY FINDINGS

Although the liver is a preferred site of metastasis, only a few studies have analysed the DTC incidence in inconspicuous liver tissue. The available reports include only patients with pancreatic and colorectal carcinomas. In patients with pancreatic cancer the DTC incidence varied from 5 to 76%. No follow-up data has been reported so far. In patients with colorectal carcinoma hepatic DTC were found in 5-69% of cases. A negative prognostic influence of hepatic DTC was reported in all but one studies with follow-up information.

CONCLUSIONS

The detection of DTC in the liver can contribute to identify patients with increased risk who could benefit from an intensified follow-up or new treatment strategies.

Disseminated tumor cells in the blood of patients with gastric cancer are an independent predictive marker of poor prognosis

OBJECTIVE

Gastric cancer carries a poor prognosis even after curative resection (R0). Tumor progression in gastric cancer patients has been attributed to the persistence of disseminated tumor cells (DTC) in various body compartments as a sign of minimal residual disease, although the prognostic relevance of DTC is still unclear. In this study the prognostic relevance of DTC in the blood of gastric cancer patients was investigated.

MATERIALS AND METHODS

Venous blood samples of 70 cancer patients were taken intraoperatively before surgical manipulation and examined by reverse transcription-polymerase chain reaction (RT-PCR) for expression of cytokeratin 20 (CK20) as a marker for DTC. Tumor-related survival was analyzed using univariate and multivariate models assessing occurrence of DTC, residual tumor classification, and tumor stage. Median follow-up was 20 months (range 1-57 months).

RESULTS

Twenty-eight of the 70 patients (40%) were CK20 positive. The prevalence of DTC in patients following R0 resection (15/41, 37%) was similar to that in patients with residual tumor (13/29, 45%, NS). Furthermore, expression of CK20 was independent of TNM stage. Univariate analysis of R0-resected patients revealed CK20 to be a marker for significantly shorter tumor-related survival (p = 0.0363). In a multivariate analysis, CK20 was an independent prognostic marker. Detection of CK20 had greatest impact for early tumor stages (T1 and T2, N0; p < 0.0032).

CONCLUSIONS

Detection of DTC in venous blood of gastric cancer patients is an independent predictive marker of poor prognosis and thus could help to define patients for adjuvant therapy with this tumor entity.

Antigenic profiles of disseminated breast tumour cells and microenvironment in bone marrow

AIMS

Thirty per cent of breast cancer patients with axillary lymph node negative at primary surgery will relapse within 10 years. This may be caused by disseminated tumour cells from the primary tumour. This study report the phenotypic profiles of disseminated tumour cells and microenvironmental characteristics in bone marrow of breast cancer.

METHODS

We detected the biologic markers on the disseminated tumour cells with immunocytochemical staining, analysed the immunological changes through flow-cytometry, and investigated the u- PA activity in the plasma of bone marrow.

RESULTS

With the immunocytochemical staining of EMA and CK19, we detected micrometastasis in thirty out of 72 (41.67%) breast cancer patients. Compared with the primary tumours, disseminated tumour cells expressed low protein cyclin D1, P53, Ki-67, EGFR, and high protein P21. The percentage of memory CD4+ T cells was significantly higher in the micrometastasis-positive group than in the micrometastasis-negative group. Tumour size and axillary lymph node status were found to be significantly correlated with the u- PA activity level.

CONCLUSIONS

Immunophenotypic profiles of disseminated tumour cells could be measured by immunocytochemical staining and microenvironment can be analysed by flow cytometry.

Comparison of two density gradient centrifugation systems for the enrichment of disseminated tumor cells in blood

BACKGROUND

The detection of disseminated tumor cells in peripheral blood is limited by the presence of very few tumor cells within a large number of blood cells. Therefore, tumor cell detection calls for enrichment systems with effective depletion of blood cells and high tumor cell recovery.

METHODS

We compared the new density gradient centrifugation method OncoQuick with the standard method of Ficoll. The enriched cell fractions were quantified. Tumor cell spiking experiments examined the recovery of tumor cells as detected by immunocytochemistry and cytokeratin-20 reverse transcriptase-polymerase chain reaction (RT-PCR). Clinical application of OncoQuick was evaluated in 37 peripheral blood samples of patients with gastrointestinal carcinomas.

RESULTS

The depletion of mononuclear cells (MNCs) in the enriched cell fraction after OncoQuick centrifugation was 632-fold, with an average cell number of 9.5 x 10(4), compared with Ficoll, with a depletion factor of 3.8 and a mean number of 1.6 x 10(7) MNCs. The mean tumor cell recovery rates were 87% for OncoQuick and 84% for Ficoll. The increased depletion of MNCs with OncoQuick centrifugation further simplified immunocytochemical evaluation by reducing the number of cytospins and increasing the tumor cell density. Due to the reduced number of co-enriched MNCs by OncoQuick, the blood volume, which could be analyzed in one RT-PCR reaction, was increased up to 30 ml. Examination of peripheral blood samples from 37 patients with gastrointestinal tumors showed a cytokeratin-20 detection rate of 30% and a significant correlation with the presence of distant metastases (P < 0.02).

CONCLUSIONS

OncoQuick significantly reduced the co-enriched number of MNCs, with a high tumor cell recovery rate. Processing blood from tumor patients with OncoQuick increased the chance of detecting circulating tumor cells.

Integration of molecular diagnostics with therapeutics: implications for drug discovery and patient care

The Introduction of targeted therapeutics into clinical practice has created major opportunities for further development of the molecular diagnostics industry. Emerging genomic and proteomic technologies and information are now resulting in the molecular subclassification of disease as the basis for diagnosis, prognosis and therapeutic selection. The ultimate goals of personalized medicine are to take advantage of a molecular understanding of disease, both to optimize drug development and direct preventive resources and therapeutic agents at the right population of people while they are still well. Single nucleotide polymorphisms identification and genotyping have uncovered predisposition markers from cancer and heart disease as well in the prediction of both drug efficacy and toxicity. Pharmacogenomic and pharmacodynamic assays are being developed to enhance the speed and decrease the cost of drug development, as well as reduce side effects and increase response rates in a variety of diseases. The traditional trial and error practice of medicine is progressively eroding in favor of more precise marker-assisted diagnosis and safer and more effective molecularly guided treatment of disease. For the diagnostics industry this represents an unprecedented opportunity for integration, increased value and commercial opportunities for molecularly-derived tests.

Integrating diagnostics and therapeutics: revolutionizing drug discovery and patient care

Over the next five years it is widely anticipated that the molecular diagnostics industry will continue to grow at double-digit pace to meet increasing demand for personalized medicine. A wide variety of drugs in late preclinical and early clinical development is now being targeted to disease-specific gene and protein defects that will require co-approval of diagnostic and therapeutic products by regulatory agencies. For clinical laboratories and pathologists, this integration of diagnostics and therapeutics represents a major new opportunity to emerge as leaders of the new medicine, guiding the selection, dosage, route of administration and multi-drug combinations, and producing increased efficacy and reduced toxicity of pharmaceutical products.