Quantification of plasma Epstein-Barr virus DNA in patients with advanced nasopharyngeal carcinoma

Role of Epstein-Barr virus DNA measurement in plasma in the clinical management of nasopharyngeal carcinoma in a low risk area

OBJECTIVE

To evaluate the role of quantitative measurement of Epstein-Barr virus (EBV) DNA in the clinical management of nasopharyngeal carcinoma (NPC) in a low tumour risk area (western Europe).

METHODS

22 consecutive Dutch NPC patients (11 europid) were studied. EBV DNA load in pretreatment and post-treatment plasma samples was determined. Three patients were also sampled at frequent intervals during treatment. RNA in situ hybridisation for the detection of EBV encoded RNAs (EBERs) was carried out on tumour biopsies of all cases.

RESULTS

All patients with EBER positive NPC (20/22) showed a positive EBV DNA load in plasma at the time of diagnosis (median EBV DNA level, 4.1 log(10) copies/ml). Patients with EBER negative NPC had no detectable EBV DNA in plasma. After treatment, complete remission was achieved in all cases and concurrently EBV DNA in plasma became undetectable in all patients. In the three longitudinally evaluated cases, EBV DNA load gradually declined towards undetectable levels within three weeks after start of treatment. Two patients developed a distant metastasis with concomitant increases in EBV viral load. In addition, one EBER positive patient developed an EBER negative metastasis in the neck during follow up and in this case EBV DNA load remained undetectable at the time of recurrence.

CONCLUSIONS

Plasma EBV DNA load measurement appears to be useful in a low tumour risk area. However, development of local recurrences may not always coincide with raised levels of EBV DNA.

Genome-wide transcription program and expression of the Rta responsive gene of Epstein–Barr virus

Infection with Epstein-Barr virus (EBV) usually leads to a latent state in B lymphocytes. The virus can be reactivated through two viral transactivators, Zta and Rta, leading to a cascade of gene expression. An EBV DNA array was generated to analyze the pattern of transcription of the entire EBV genome under various conditions. Firstly, a complete set of temporal expression clusters of EBV genes was displayed by analyzing the array data of anti-IgG-induced Akata cells. In addition to assigning genes of unknown function to the various clusters, increasing expression of latent genes, including EBNA2, EBNA3A and EBNA 3C, was observed during virus replication. Secondly, gene expression independent of viral DNA replication was analyzed in PAA blocked Akata cells and in chemically induced Raji cells. Several genes with presumed late functions were found to be expressed with early kinetics and independent of viral DNA replication, suggesting possible novel functions for these genes. Finally, the EBV array was used to identify Rta responsive gene expression in Raji cells, and in the EBV-positive epithelial cells NA, using a Zta siRNA strategy. The array data were confirmed by Northern blotting, RT-PCR and reporter assays. All the information here thus provides a better understanding of the control of EBV lytic gene expression.

Clinical value of Epstein–Barr virus DNA levels in peripheral blood samples of Italian patients with Undifferentiated Carcinoma of Nasopharyngeal Type

We investigated EBV viremia in matched serum and peripheral blood mononuclear cells (PBMCs) from one of the largest Italian cohort of Undifferentiated Carcinoma of Nasopharyngeal Type (UCNT) patients (N=34). By using a LMP-1 real-time PCR assay, we found that EBV DNA detection rate was 74% (median 8417 copies/ml) and 24% (median 164 copies/10(6)cells) on serum and PBMCs, respectively. Significantly higher serum EBV DNA levels were detected in patients with advanced UCNT (nodal stage N2 versus N0-1 and N3 versus N0-1, P=0.03 and 0.018; overall stage IV versus I-II, P=0.03). During the follow-up, there was also a statistically significant difference of EBV DNA viral load between patients with and without clinical relapse (P=0.008). We concluded that serum EBV DNA reflects the biological activity of the UCNT and may be a prognostic factor also in a low-incidence region.

Real-time PCR in clinical microbiology: applications for routine laboratory testing

Real-time PCR has revolutionized the way clinical microbiology laboratories diagnose many human microbial infections. This testing method combines PCR chemistry with fluorescent probe detection of amplified product in the same reaction vessel. In general, both PCR and amplified product detection are completed in an hour or less, which is considerably faster than conventional PCR detection methods. Real-time PCR assays provide sensitivity and specificity equivalent to that of conventional PCR combined with Southern blot analysis, and since amplification and detection steps are performed in the same closed vessel, the risk of releasing amplified nucleic acids into the environment is negligible. The combination of excellent sensitivity and specificity, low contamination risk, and speed has made real-time PCR technology an appealing alternative to culture- or immunoassay-based testing methods for diagnosing many infectious diseases. This review focuses on the application of real-time PCR in the clinical microbiology laboratory.

A Comparison Study of Different PCR Assays in Measuring Circulating Plasma Epstein-Barr Virus DNA Levels in Patients with Nasopharyngeal Carcinoma

PURPOSE

To compare the performance of three PCR assays in measuring circulating Epstein-Barr virus (EBV). DNA levels in nasopharyngeal carcinoma patients and to confirm its prognostic significance.

EXPERIMENTAL DESIGN

Plasma from 58 newly diagnosed nasopharyngeal carcinoma patients were collected before, during, and every 3 to 6 months after radiotherapy. EBV DNA levels were determined by real-time quantitative PCR using primer/probe sets for polymerase-1 (Pol-1), latent membrane protein 2 (Lmp2), and BamHI-W. Pretreatment levels from the three assays were correlated with each other and serial measurements from the Pol-1 assay were correlated with clinical variables.

RESULTS

Pol-1 was more accurate than BamHI-W in predicting EBV DNA concentrations in cell lines. Of the three assays, BamHI-W yielded the highest concentrations followed by Pol-1 in plasmas (n = 23). The correlation coefficient was 0.99 (P < 0.0001) for Pol-1 and Lmp2, 0.66 (P < 0.0001) for Pol-1 and BamHI-W, and 0.55 (P < 0.0001) for BamHI-W and Lmp2. Elevated pretreatment DNA levels as detected by Pol-1 were correlated with advanced nodal stage (P = 0.04) and overall stage (P = 0.028). There was no correlation between pretreatment EBV DNA levels and freedom-from-relapse or overall survival; however, there was a significant correlation between posttreatment levels and these variables. The 2-year freedom-from-relapse and overall survival rates were 92% and 94% for patients with undetectable, and 37% and 55% for those with detectable, posttreatment levels (P < 0.0001 and P < 0.002).

CONCLUSIONS

The three PCR assays yielded similar results in detecting EBV DNA in plasmas. The Pol-1-detected posttreatment EBV DNA level was the strongest predictor for treatment outcomes.

Distribution of Epstein-Barr viral load in serum of individuals from nasopharyngeal carcinoma high-risk families in Taiwan

The utility of EBV load as a tumor marker in nasopharyngeal carcinoma (NPC) patients suggests that it might also serve as a screening test for individuals who are at high risk for developing NPC. We previously demonstrated that unaffected individuals from high-risk families had elevated anti-EBV antibody levels compared to community controls. In this study, we measured EBV load using 2 different real-time PCR assays (targeting BamH1W and polymerase gene sequences, respectively) carried out in 2 independent research labs in serum samples from 19 untreated NPC cases, 11 healthy community controls and 100 unaffected individuals from families in which 2 or more individuals were affected with NPC. EBV genomes were detectable in 68% of NPC cases by the EBV BamH1W assay and in 74% by the EBV polymerase assay (kappa = 0.64). Patients with stage III or IV disease had significantly higher EBV load compared to those with stage I or II disease (p = 0.008). EBV DNA was detected in a single community control sample by the EBV BamH1W assay and in none of the samples by the EBV polymerase assay. Only one of 100 unaffected family members tested positive by both assays. An additional 14 were positive by only one of the 2 EBV load assays used and usually in only one of the duplicate wells tested, all with very low viral loads (3-50 copies/ml). In addition, EBV load did not correlate with EBV serology results (anti-VCA, anti-DNase, anti-EBNA-1) among these unaffected family members. In conclusion, our study suggests limited clinical utility of the EBV load test, in its current configuration, to screen individuals from high-risk families. Should a more sensitive or specific molecular assay be developed that is capable of detecting and distinguishing tumor-derived EBV genomes or gene products from true negatives, it could be evaluated as a possible screening tool for asymptomatic and early-stage NPC.

Basic principles of real-time quantitative PCR

Real-time quantitative PCR allows the sensitive, specific and reproducible quantitation of nucleic acids. Since its introduction, real-time quantitative PCR has revolutionized the field of molecular diagnostics and the technique is being used in a rapidly expanding number of applications. This exciting technology has enabled the shift of molecular diagnostics toward a high-throughput, automated technology with lower turnaround times. This article reviews the basic principles of real-time PCR and describes the various chemistries available: the double-stranded DNA-intercalating agent SYBR Green 1, hydrolysis probes, dual hybridization probes, molecular beacons and scorpion probes. Quantitation methods are discussed in addition to the competing instruments available on the market. Examples of applications of this important and versatile technique are provided throughout the review.

Diagnostic value of measuring Epstein-Barr virus (EBV) DNA load and carcinoma-specific viral mRNA in relation to anti-EBV immunoglobulin A (IgA) and IgG antibody levels in blood of nasopharyngeal carcinoma patients from Indonesia

Nasopharyngeal carcinoma (NPC) is a prevalent malignancy in Southeast Asia and is strongly associated with Epstein-Barr virus (EBV). We investigated the primary diagnostic value of circulating EBV DNA and anti-EBV immunoglobulin G (IgG) and IgA levels in Indonesian NPC patients (n = 149). By a 213-bp Epstein-Barr virus nuclear antigen 1 (EBNA1)-based real-time LightCycler PCR, 72.5% of patients were positive for EBV DNA in whole blood, with 29.5% having levels above a previously determined clinical cutoff value (COV) of 2,000 EBV DNA copies/ml, the upper level in healthy carriers. In a 99-bp LightCycler PCR, 85.9% of patients were positive and 60.4% had levels above the COV. This assay quantified a significantly higher EBV load than the 213-bp PCR assay (P < 0.0001), suggesting that circulating EBV DNA is fragmented. Using data from 11 different studies, we showed a significant inverse correlation between PCR amplicon size and the percentage of patients positive for circulating EBV DNA (Spearman's rho = -0.91; P < 0.0001). EBV DNA loads were unrelated to anti-EBV IgG or IgA levels, as measured by VCA-p18 and EBNA1-specific synthetic peptide-based enzyme-linked immunosorbent assays. The presence of circulating tumor cells was assessed by amplification of BamHI-A rightward frame 1 (BARF1) mRNA, a viral oncogene abundantly expressed in EBV-carrying carcinomas but virtually absent from EBV-associated lymphomas. Despite high EBV DNA loads and the presence of EBNA1 and human U1A small nuclear ribonucleoprotein mRNA, BARF1 mRNA was never detected in blood. We conclude that amplicon size significantly influences EBV DNA load measurement in NPC patients. The circulating EBV DNA load is independent of serological parameters and does not reflect intact tumor cells. The primary diagnostic value of the EBV DNA load for the detection of NPC is limited.

Nasopharyngeal carcinoma

Incidence of nasopharyngeal carcinoma has remained high in endemic regions. Diagnosing the disease in the early stages requires a high index of clinical acumen and, although most cross-sectional imaging investigations show the tumour with precision, confirmation is dependent on histology. Epstein-Barr virus (EBV)-encoded RNA signal is present in all nasopharyngeal carcinoma cells, and early diagnosis of the disease is possible through the detection of raised antibodies against EBV. The quantity of EBV DNA detected in blood indicates the stage and prognosis of the disease. Radiotherapy with concomitant chemotherapy has increased survival, and improved techniques (such as intensity-modulated radiotherapy), early detection of recurrence, and application of appropriate surgical salvage procedures have contributed to improved therapeutic results. Screening of high-risk individuals in endemic regions together with developments in gene therapy and immunotherapy might further improve outcome.

Epstein-Barr Virus Infection-Associated Smooth-Muscle Tumors in Patients with AIDS

BACKGROUND

The aim of our study is to describe the unusual clinical manifestations of smooth-muscle tumors (SMTs) in patients with acquired immunodeficiency virus (AIDS) and to demonstrate the association between Epstein-Barr virus (EBV) infection and SMTs.

METHODS

Nine patients with AIDS and SMTs were characterized at Chulalongkorn Hospital (Bangkok, Thailand) from 2001 through 2003. Tumor tissues suitable for immunohistochemical analysis and in situ hybridization were assayed for SMTs and EBV, respectively. Plasma and serum samples were tested for EBV by real-time quantitative polymerase chain reaction and serologic analysis.

RESULTS

The study included 8 adults and 1 child (3 males and 6 females). All patients had CD4 cell counts of <200 cells/microL. By the end of the study, 3 patients had died, and 6 patients had survived. The sites of SMTs were the epidura (5 intracranial and 4 intraspinal SMTs), vocal cords (2), adrenal glands (2), abdominal wall (2), iris (1), liver (1), lung (1), orbit (1), and thigh (1). Seven patients had multicentric SMTs involving intracranial sites only (4 SMTs), extra- and intracranial sites (3), or extracranial sites only (2), which occurred either concurrently or sequentially. We found evidence of EBV infection, as determined by in situ hybridization, in all SMTs. Furthermore, EBV DNA was detectable in plasma samples from 2 patients. The results of serologic analysis were consistent with past EBV infection.

CONCLUSIONS

SMTs in patients with AIDS typically arise in multiple and very unusual sites that are not often observed in SMTs among immunocompetent individuals. Our series also suggests association between EBV infection and SMTs in patients with AIDS. The exact role of EBV in smooth-muscle oncogenesis awaits further study.

High frequency of frameshift mutation on p53 gene in Taiwanese with non small cell lung cancer

Extensive researches have found that the mutation of p53 tumor suppressor gene is the most frequent event in many human cancers and associated with a poor clinical outcome in lung cancer patients. Because the p53 molecular mutation involved in tumorigenesis of patients with lung cancer in Taiwan remains poorly defined, the aim of this study was to assess the p53 mutation spectrum and possible etiological factors of Taiwan's patients with Non-Small Cell Lung Cancer (NSCLC). Cancer specimens were obtained surgically from 61 patients with pathologically proven NSCLC. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and direct sequencing were used to study p53 mutations in exon 4-8. We also performed immunohistochemistry (IHC) to detect p53 protein expression. Our results provided that 34 mutations of p53 gene were found in 27 cases with a mutation rate of 44% (27/61). There were six cases having more than two p53 mutations. Among the 34 mutations, 19 were point mutations (56%, 19/34) consisted of a majority of missense mutations including transversion (13/19, 68%) and transitions (6/19, 32%) with four cases (4/6, 67%) occurring in the CpG sequence. One of the most important finding in our study was the high frequency of frameshift (44%, 15/34) which included 11 insertions and 4 deletions of p53 in NSCLC in Taiwan. Surprisingly, our results disclosed distinct novel mutations at codon 181, 185, 208 (Exon 5-6) of p53. Especially, 4 cases with mutation at codon181 and codon 185 seemed to have more advanced clinical outcome with survival time less than 6 months. In addition, there were two recurring mutations at codon 168 and three at condon193. The different mutation spectrum in our series, including a high frequency of frameshift mutations and distinctly novel hot spots suggested the heterogenous entity of exogenous mutagens in NSCLC in Taiwan.

Advances in nasopharyngeal carcinoma

PURPOSE OF REVIEW

Intergroup 0099 established the role of concurrent chemotherapy with radiation therapy in the treatment of locally advanced nasopharyngeal carcinoma, but its reproducibility was unclear and chemotherapy compliance was poor. Multiple concurrent chemoradiation phase III trials were initiated in response to the Intergroup trial, and technologic advances in radiotherapy were explored to improve the therapeutic ratio. This review highlights recent advances in the management of nasopharyngeal carcinoma as a result of these endeavors.

RECENT FINDINGS

Five randomized phase III trials confirmed the benefit of concurrent chemoradiation over radiation therapy alone, firmly establishing concurrent chemoradiation as the standard of care in locally advanced nasopharyngeal carcinoma. Each of these studies used conventional radiation therapy and noted an increase in toxicity over radiation therapy alone. Intensity-modulated radiation therapy is an advanced form of three-dimensional conformal radiotherapy which allows delivery of high doses of radiation to the tumor while sparing adjacent normal tissues, leading to improved local control and decreased radiation therapy-induced toxicities. Distant metastasis remains a significant problem despite intensity-modulated radiation therapy. Taxane-based induction chemotherapy seems promising in phase II studies. Targeted therapies remain a major area of interest and require further investigation.

SUMMARY

Cisplatin-based concurrent chemoradiation followed by adjuvant chemotherapy is the standard of care for locally advanced nasopharyngeal carcinoma. Intensity-modulated radiation therapy has undergone a rapid evolution and is replacing conventional radiation therapy in many institutions. A multidisciplinary effort is under way to explore more effective systemic therapy to improve the distant metastasis free rates.

Efficacy of Epstein-Barr virus removal by leukoreduction of red blood cells

BACKGROUND

Epstein-Barr virus (EBV) infection results in life-long carriage of latent virus in B lymphocytes in the majority of the adult population, including blood donors. The removal of EBV from red blood cell (RBC) components by leukoreduction was assessed.

STUDY DESIGN AND METHODS

Sixteen randomly selected fresh AS-5 units were leukoreduced by filtration. B lymphocytes from preleukoreduction specimens and mononuclear cells (MNCs) from postleukoreduction specimens were assayed for EBV DNA with sensitive real-time polymerase chain reaction (PCR).

RESULTS

EBV genomes were detected in CD19+ B cells in 14 of 16 preleukoreduced RBC units. EBV genomic copy number in the units ranged from 0.18 to 96.84 per 10(5) B lymphocytes representing approximately 135 to 72,630 total EBV genomes per bag. Leukoreduction rendered all but one unit EBV-negative by PCR. The lone PCR-positive unit after leukoreduction amplified 1.2 EBV genome copies from MNCs recovered from the entire unit of leukoreduced RBCs; this unit had the highest EBV viral load before leukoreduction (72,630 EBV genomes).

CONCLUSIONS

These results indicate that a 4-log reduction of EBV genomic copy number can be achieved with leukoreduction of RBC units and renders most RBC units EBV-negative by sensitive PCR.

State-of-the-art management of nasopharyngeal carcinoma: current and future directions

Nasopharyngeal carcinoma (NPC) is a distinct type of head and neck cancer. Approximately 70% of patients with newly diagnosed NPC present with locally advanced disease. Phase III clinical trials support the addition of chemotherapy to radiotherapy for the initial treatment of these patients. Once metastatic disease develops, practices become varied. Further experience needs to be gained with both targeted therapies and immunotherapy to gauge whether they will improve treatment outcomes in NPC.

INFECTIOUS DISEASES

The emergence of new pathogens, or the concern about bioterrorism, has brought an added urgency to the development of more efficient and rapid methods to detect pathogens and predict their potential virulence. Till date, DNA testing in microbiology has been directed predominantly to the detection of organisms that are difficult to culture in vitro, or for various reasons the growth is unlikely. DNA analysis can be used successfully in infections in which there is a mix of pathogens. Apart from the straightforward diagnostic applications, DNA microbiological testing has been used to detect antimicrobial resistance or toxigenic forms of E. coli. More recently, the availability of DNA technology to quantitate HCV and HIV has been useful in planning and monitoring treatment. The pathogenesis of many infections, particularly viral ones, can also be realized from experimental strategies based on light and electron microscopy, cell culture and immunoassay. The advantages that are provided by DNA techniques include the ability to detect latent (non-replicating) viruses and to localize their genomes to nuclear or cytoplasmic regions within cells. Nucleic acid probe techniques (NAT) can also be manipulated to enable a broad spectrum of serotypes to be detectable. This is particularly valuable in those emerging infections where the underlying serotypes are unknown.

Preradiation chemotherapy with methotrexate, cisplatin, 5-fluorouracil, and leucovorin for pediatric nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is rare in children, accounting for <1% of all cases. Treatment most commonly includes radiotherapy but long-term side effects of such treatment can produce devastating cosmetic and functional sequelae in children. Chemotherapy may help to decrease the radiotherapy dose and limit the side effects of local therapies. However, little is known regarding the chemosensitivity of NPC tumors in pediatric patients.

METHODS

Patients with American Joint Committee on Cancer (AJCC) Stage I/II disease (Stratum 01) received irradiation only. Patients with AJCC Stage III/IV disease (Stratum 02) received 4 courses of preradiation chemotherapy comprising methotrexate (120 mg/m2) on Day 1, with cisplatin (100 mg/m2) 24 hours later, 5-fluorouracil 1000 mg/m2 per day as a continuous infusion for 3 days, and leucovorin 25 mg/m2 every 6 hours for 6 doses. Irradiation was given after chemotherapy and consisted of 50.4 gray (Gy) to the upper neck and 45.0 Gy to the lower neck, with a boost to the primary tumor and positive lymph nodes for a total dose of 61.2 Gy.

RESULTS

One patient was enrolled in Stratum 01 and 16 evaluable patients were enrolled in Stratum 02. The median age of the patients was 13 years and 65% of the patients were black. All patients tested had evidence of Epstein-Barr virus infection. Two-thirds of the patients developed Grade 3-4 mucositis during chemotherapy. The overall response rate to induction chemotherapy was 93.7%. The overall 4-year event-free and overall survival rates (+/- the standard error) were 77%+/-12% and 75%+/-12%, respectively.

CONCLUSIONS

The current study demonstrated that childhood NPC was sensitive to chemotherapy and that chemotherapy before irradiation was feasible. Future trials should investigate equivalent efficacy with a reduced radiotherapy dose.

Hodgkin's lymphoma: evolving concepts with implications for practice

Hodgkin's lymphoma is a unique neoplasm of B lymphocytes. Recent data provide new understandings of the pathogenesis and options for staging and therapy of the disease. Three specific topics are addressed in this chapter. In Section I, Dr. Richard Ambinder reviews implications of the relationship of Epstein-Barr virus (EBV) and Hodgkin's lymphoma. This relation includes varying geographic epidemiologic associations, including varying associations with the clinical syndrome of infectious mononucleosis. There are plausible mechanisms, including processes initiated by viral proteins, by which EBV might lead to tumorigenesis. These mechanisms include promotion of genetic instability and alteration of normal processes of apoptosis. In addition to an epidemiologic association and potential role in pathogenesis, viral antigens may pose theoretical targets for anti-cancer therapies, including vaccination. In Section II, Dr. Sigrid Stroobants describes the potential role of positron emission tomographic (PET) scanning. By assessing differences in the metabolic activities of cancer cells, PET scanning may be superior to computerized tomographic scanning, which is limited to showing structural anatomical abnormalities. In patients with Hodgkin's and non-Hodgkin's lymphoma, PET scanning has been tested as an initial staging tool, to assess the rate of therapeutic response from a prognostic perspective, and to differentiate residual tumor from fibrotic masses in patients who have completed therapy. Particularly in assessing the nature of a residual mass seen with other post-therapeutic imaging modalities, PET scanning may provide unique information; very high negative predictive values have been reported. However, before this technology can be recommended for incorporation into standard management, properly conducted prospective trials are required to better evaluate the clinical utility of PET with respect to eventual patient outcomes. In Section III, Dr. Ralph Meyer reviews current data regarding the management of patients with limited-stage Hodgkin's lymphoma. Over the past decade, standard treatment has evolved to consist of combined-modality therapy that includes an abbreviated course of chemotherapy and involved-field radiation. As this therapy continues to include radiation therapy, patients will remain at risk of long-term toxicities that include the development of second cancers and cardiovascular events. These "late-effects" now account for more deaths than those attributed to progressive Hodgkin's lymphoma. Comparative data testing the role of chemotherapy alone are now available and demonstrate that omission of radiation therapy results in small but statistically significant reduction in disease control, but no detectable differences in overall survival. Further follow-up will clarify whether chemotherapy alone is the preferred treatment option; at present patients should be informed of the trade-offs involved in choosing between this option and combined modality therapy.