IgA directed against early antigen of Epstein-Barr virus is no specific marker for the diagnosis of nasopharyngeal carcinoma

Screening for nasopharyngeal cancer

BACKGROUND

Nasopharyngeal cancer is endemic in a few well-defined populations. The prognosis for advanced nasopharyngeal cancer is poor, but early-stage disease is curable and a high survival rate can be achieved. Screening for early-stage disease could lead to improved outcomes. Epstein-Barr virus (EBV) serology and nasopharyngoscopy are most commonly used for screening. The efficacy and true benefit of screening remain uncertain due to potential selection, lead-time and length-time biases.

OBJECTIVES

To determine the effectiveness of screening of asymptomatic individuals by EBV serology and/or nasopharyngoscopy in reducing the mortality of nasopharyngeal cancer compared to no screening. To assess the impact of screening for nasopharyngeal cancer on incidence, survival, adverse effects, cost-effectiveness and quality of life.

SEARCH METHODS

The Cochrane Ear, Nose and Throat Disorders Group (CENTDG) Trials Search Co-ordinator searched the CENTDG Trials Register; Central Register of Controlled Trials (CENTRAL 2015, Issue 6); PubMed; EMBASE; CINAHL; Web of Science; Clinicaltrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 6 July 2015.

SELECTION CRITERIA

Randomised controlled trials (RCT) and controlled clinical trials (CCT) evaluating screening for nasopharyngeal cancer versus no screening. Randomisation either by clusters or individuals was acceptable.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration. Our primary outcome measure was nasopharyngeal cancer-specific mortality. Secondary outcomes were incidence of nasopharyngeal cancer by stage and histopathological classification at diagnosis, survival (two-year, three-year, five-year and 10-year), harms of screening (physical and psychosocial), quality of life (via validated tools such as the SF-36 and patient satisfaction), cost-effectiveness and all-cause mortality.

MAIN RESULTS

We identified no trials that met the review inclusion criteria. We retrieved 31 full-text studies for further investigation following the search. However, none met the eligibility criteria for a RCT or CCT investigation on the efficacy of screening for nasopharyngeal cancer.

AUTHORS' CONCLUSIONS

No data from RCTs or CCTs are available to allow us to determine the efficacy of screening for nasopharyngeal cancer, or the cost-effectiveness and cost-benefit of a screening strategy. High-quality studies with long-term follow-up of mortality and cost-effectiveness are needed.

Analyses of the prognostic significance of the Epstein-Barr virus transactivator ZEBRA protein and diagnostic value of its two synthetic peptides in nasopharyngeal carcinoma

BACKGROUND

Although numerous serological studies have determined the diagnostic and prognostic values of Epstein-Barr virus (EBV) antibodies in adult patients with nasopharyngeal carcinoma (NPC), little data about the anti-EBV immune response in children with NPC is available.

OBJECTIVES

To examine the diagnostic value of IgG antibodies against BamHI Z Epstein-Barr replication activator (ZEBRA) protein and two related synthetic peptides (Zp125 and Zp130). To compare the prognostic value of IgA antibodies against early antigens (EA) and viral capsid antigen (VCA), and IgG antibodies against ZEBRA protein, of Moroccan children treated for NPC with their prognostic value for young and adult NPC patients.

STUDY DESIGN

Sera were collected from 255 newly diagnosed Moroccan NPC patients and 226 healthy donors. IgA antibody against VCA and EA was measured by immunofluorescence assays. IgG antibody against ZEBRA, Zp125, and Zp130 was measured by ELISA.

RESULTS

No significant difference in the detection of IgG-Zp125 and Zp130 antibodies was observed in children with NPC. IgG-Zp130 were detected less frequently than IgG-Zp125 in young and adult patients, as compared to children. High specificity of IgG-Zp125 and -Zp130 antibodies was found in the three age groups. A decrease in IgG-ZEBRA was observed in patients with NPC in clinical remission, whereas patients with NPC who died or developed metastases maintained or had an increase in these titers.

CONCLUSION

IgG-ZEBRA is a better diagnostic and post-therapeutic prognostic marker in children with NPC, who showed very low titers of IgA -VCA and -EA.

Native early antigen of Epstein-Barr virus, a promising antigen for diagnosis of nasopharyngeal carcinoma

The Epstein-Barr virus (EBV) early antigen (EA) complex consists of multiple proteins with relevance for diagnosis of acute, chronic and malignant EBV related diseases, including nasopharyngeal carcinoma (NPC). In a recent study, it was found that the molecular diversity of EBV-specific IgG and IgA antibody responses in NPC patients and demonstrated that these reflect independent B-cell triggering leading to distinct EBV antigen-recognition profiles. The fine-specificity of NPC-related IgG and IgA responses was explored further against defined recombinant and synthetic EBV-EA antigens using immunofluorescence, immunoblot and ELISA techniques and determined their diagnostic value in a large panel of sera from NPC (n = 154), non-NPC tumor patients (n = 133), acute mononucleosis patients (n = 70) and healthy EBV carriers (n = 259). Individual recombinant EBV-EA markers yielded sensitivity/specificity values not exceeding 86%, whereas selected EA-specific peptide epitopes were rather poorly recognized by IgG and IgA antibodies in NPC sera. Surprisingly, we found that a "low salt" native EA-protein extract reproducibly prepared from purified nuclei of EA-induced HH514 cells, and containing characteristic EA(D)-polypeptides, such as p47-54 (BMRF1), p138 (BALF2), p55-DNAse (BGLF5), and p65-TK (BXLF1), but without viral capsid (VCA) or nuclear antigen (EBNA) reactivity, gave highest sensitivity (90.4%) and specificity (95.5%) values for NPC diagnosis in both IgG and IgA ELISA. The data support further the notion that EBV-EA reactive IgG and IgA antibodies in NPC patients are directed against distinct conformational and-in part-linear epitopes on EBV-specific proteins, barely recognized in other EBV-related syndromes. The use of a defined native EBV EA-specific antigen opens the way to further improve serological diagnosis of NPC.

Cancer cell-secreted proteomes as a basis for searching potential tumor markers: nasopharyngeal carcinoma as a model

Nasopharyngeal carcinoma (NPC) is commonly diagnosed late due to its deep location and vague symptoms. To identify biomarkers for early NPC diagnosis, secreted proteomes of two NPC cell lines were analyzed. Proteins in the NPC cell-line cultured media were systematically identified by SDS-PAGE combined with MALDI-TOF MS. Twenty-three proteins were found in cultured media from both NPC cell lines. Among them, fibronectin, Mac-2 binding protein (Mac-2 BP), and plasminogen activator inhibitor 1 (PAI-1) were further confirmed by Western blot analysis. These three proteins were highly expressed in NPC biopsies, but weakly or not expressed in normal nasopharyngeal tissues. The serum levels of the three proteins were significantly higher in NPC patients (n = 46) than in normal controls (n = 47) (p < 0.01). NPC nude mice model (n = 9) also showed elevated levels of serum Mac-2 BP and PAI-1 compared with tumor-free mice (n = 9) (p < 0.01). Systematic analysis of cancer cell-secreted proteomes combined with animal tumor models can be a feasible, convenient strategy for searching multiple potential tumor markers. Furthermore, our work shows that fibronectin, Mac-2 BP, and PAI-1 may be potential markers for diagnosis of NPC.

Quantitative plasma hypermethylated DNA markers of undifferentiated nasopharyngeal carcinoma

PURPOSE

Gene-specific methylation is common in primary undifferentiated nasopharyngeal carcinoma (NPC). DNA released from apoptotic or necrotic cell death including those aberrantly methylated promoter DNA of cancer cells is absorbed into the circulation as cell-free plasma DNA of the patient. This study aims at evaluation of the potential use of methylated gene promoter DNA as a serological tumor marker of primary and potentially salvageable local or nodal recurrent NPC.

EXPERIMENTAL DESIGN

The quantity of plasma hypermethylated gene promoters of CDH1, DAPK1, p15, p16, RASSF1A, and MLH1 of 41 NPC patients before treatment and 43 normal individuals were studied using real-time quantitative PCR. The post-treatment plasma hypermethylated CDH1, DAPK1,and p16 were also measured in 13 NPC patients with locoregional recurrence and 17 patients in remission.

RESULTS

Concentrations of cell-free circulating DNA were significantly higher in NPC patients than normal controls (28.79 ng/ml versus 16.57 ng/ml, respectively). There was no significant difference in plasma DNA concentration of EBV-positive and -negative normal individuals. Methylated DNA was detectable in plasma of NPC patients before treatment including 46% for CDH1,42% for p16,20% for DAPK1,20% for p15,and 5% for RASSF1A. Hypermethylated MLH1 was not detected in plasma of all of the NPC patients and normal individuals. Aberrantly hypermethylated promoter DNA of at least one of the five genes was detectable in 29 of 41 (71%) plasma of NPC patients before treatment. Hypermethylated promoter DNA of at least one of the three genes (CDH1, DAPK1, and p16) was detectable in post-treatment plasma of 5 of 13 (38%) recurrent NPC patients and none of the patients in remission.

CONCLUSIONS

Our results suggested that cell-free circulating methylated gene promoter DNA is a possibly useful serological marker in assisting in screening of primary and potentially salvageable local or regional recurrent NPC.

Regulation of the H19 imprinting gene expression in human nasopharyngeal carcinoma by methylation

In East Asia and Singapore, the human nasopharyngeal carcinoma (NPC) presented clinically is mainly of the undifferentiated type. In contrast, the well-differentiated squamous NPC is more commonly detected in the West. To study the potential differences in carcinogenesis between undifferentiated and differentiated human NPC, we employed cDNA microarrays to isolate genes that might be specific for human undifferentiated NPC. One of the genes identified to be specifically upregulated in the undifferentiated human NPC cell line CNE-2 is the human imprinting gene H19. Interestingly, H19 is not expressed in the well-differentiated human HK1 NPC cells. Northern blot and in situ hybridization analyses also confirmed that the H19 gene is strongly expressed in the undifferentiated CNE-2 human NPC cell line but not in the well-differentiated HK1 human NPC cell line. In situ hybridization and reverse transcriptase-polymerase chain reaction also demonstrated that H19 is specifically expressed in NPC biopsies and not in non-NPC human tissue biopsies. Furthermore, we demonstrated that deregulation of H19 gene expression in the well-differentiated human HK1 NPC cells could be induced by the hypomethylation of CpG sites of the H19 promoter region. Hypermethylation of gene promoter regions might therefore be an important epigenetic event that plays a role in the differentiation of human NPC cells and the transcriptional silencing of imprinted genes.

Longitudinal sero-reactivity to human herpesvirus 8 (KSHV) in the Swiss HIV Cohort 4.7 years before KS

The relationship between viral infection with Kaposi sarcoma-associated herpesvirus (KSHV) and the onset of Kaposi sarcoma (KS) in AIDS patients is incompletely understood. This study investigates the use of three serological assays to predict the development of KS in HIV-positive patients. Serially collected serum samples from 36 patients with KS and matched controls in the Swiss HIV Cohort Study (SHCS) were analyzed in a case control study. Three serologic assays to detect antibodies against KSHV (nuclear and membrane antigen immunofluorescence assay, N-IFA, M-IFA and ORF 65.2 ELISA) were used to determine the predictive value of KSHV-seropositivity. Serial samples from the cases were also analyzed to determine longitudinal patterns of seroreactivity and identify cases of seroconversion. Assay sensitivity for detection of KSHV antibodies was highest for M-IFA (83%), followed by N-IFA (74%) and 65.2 ELISA (52%). At the time of initial serum sampling (median 4.7 years before KS), only the N-IFA distinguished case and control sera (61% vs. 32%) and no assay was clearly predictive of subsequent onset of clinical KS. Moreover, an unexpectedly high rate of reversions to seronegativity were observed by N-IFA (27/33) as well as by 65.2 ELISA (11/26) in the longitudinal analysis. Analysis of the ORF65.2 ELISA index indicated that these reversions before the clinical onset of KS were associated with antibody levels that frequently hovered around the level of detectability. A marked increase in ORF 65.2 antibody titer occurred in a third of the patients at the time of KS diagnosis. Only two seroconversions were documented. KSHV infection within the SHCS is likely to have preceded HIV infection. KSHV infection alone is not highly predictive of KS development in this cohort of HIV-infected homosexual men as compared with matched controls. Three KSHV serologic assays, though sensitive at the time of clinical KS are inconsistently positive before the development of AIDS-related KS.

Antibodies to the Epstein-Barr virus transactivator protein (ZEBRA) as a valuable biomarker in young patients with nasopharyngeal carcinoma

Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) generally occurs in adults, especially in high-prevalence populations such as the Chinese and Eskimos. In Maghrebian populations, young patients affected with this malignancy represent 25% of the total NPC cases. In adults with NPC, relatively high titers of IgA antibodies to the EBV viral capsid antigen (VCA) and early antigen (EA) represent important markers. However, nearly 50% of young NPC patients are negative for IgA-anti-VCA and -EA or exhibit very low titers of these antibodies. We report here that 92% of sera from young NPC patients negative for IgA-EA and 89% of those negative for IgA-VCA were positive for IgG antibodies to the EBV transactivator protein (ZEBRA) at very high titers. Our results show that in young patients with NPC these antibodies represent the most reliable marker for diagnosis and prognosis, particularly when compared with conventional NPC markers, i.e., IgA-VCA (58%) and anti-EA (25%). The titers of IgG-ZEBRA antibodies increased along with lymph node involvement only in the young patient group, suggesting a prognostic value of this marker in this patient group.

Epstein-Barr Viral Antigens Used in the Diagnosis of Nasopharyngeal Carcinoma

The major antigen complexes of Epstein-Barr virus (EBV) include the latent infectious proteins, early antigens, membrane antigens and viral capsid antigens. The various polypeptides within each antigen complex have been identified and isolated through gene-cloning technology. These polypeptides are exploited to be used as serological markers for the diagnosis of nasopharyngeal carcinoma (NPC) through enzyme-linked immunosorbent assay. This paper reviews the recent studies on the profile of antibodies in patients with NPC towards these EBV polypeptides of each antigen complex. The sensitivity and specificity of each polypeptide when used as serological markers to NPC patients' sera are summarized. Copyright 1996 S. Karger AG, Basel

Evaluation of 11 enzyme immunoassays for the detection of immunoglobulin M antibodies to Epstein-Barr virus

Laboratory diagnosis of Epstein-Barr virus (EBV) infection is based mainly on serological tests. The analysis of the pattern of class-specific immunoglobulin response against defined viral antigens, i.e. virus capsid antigen (VCA), early antigen (EA) and Epstein-Barr nuclear antigen (EBNA), permits the differentiation between primary, latent and secondary (reactivated) EBV infection. In recent months, numerous test kits for the detection of VCA specific IgM antibody have been introduced on the international market. With a panel of well defined sera, the sensitivity and specificity of eleven different commercially available IgM ELISAs was evaluated. A well established, commercially available, indirect immunofluorescence assay (IFA) served as the reference test. Compared to the IFA, the Biotest and Sigma Diagnostic assays had the highest sensitivity for the detection of IgM antibody to VCA or EA. A variable number of false positive results (n = 0-9) was obtained with the EBV-IgM assays by testing potentially cross-reactive serum samples. Up to 19 serum samples from immunocompromised organ transplant recipients were found positive with the Sigma Diagnostics assay. The results of this study show that there are great differences in quality of current EBV-IgM-ELISA test kits. Depending on the clinical setting, it may be important to use a test kit which detects immunoglobulin M reactivity to EA in order to warrant an optimal sensitivity for the serological diagnosis of EBV reactivation in immunocompromised patients. However, since most immunosuppressed patients have serological reactivations, and in most cases these are asymptomatic, the clinical relevance of the detection of EA-IgM is very low.

Compact Epstein-Barr virus diagnosis based on a defined antigen mix and specific IgA

An ELISA was evaluated to measure EBV-specific IgM, IgG and IgA using a test plate coated with a controlled mix of EA, VCA and EBNA. Using the IgM version, the multi-reactive surface reduced false-negative findings in cases of infectious mononucleosis (sensitivity 98%), but was confronted with polyclonal IgM responses (specificity 85% to 95% depending on the population). For the IgG version, a national research standard was involved, and in combination with the IgA estimation, a new diagnostic strategy became possible for chronic EBV infections and reactivations. Patients screened by enhanced IgG (> 650 U/ml) were confirmed by an elevated IgA signal (> 0.6 A), with an efficacy of 95%. A raised virus-specific IgA response was not observed in cases of infectious mononucleosis, but was seen for healthy HIV-positive persons. Superior to the traditional antibody puzzle for EBV diagnosis, it will now become possible, using this compact diagnostic concept, to reduce laboratory expenses without loss of reliable results.