The clinical significance of EBV DNA in the plasma and peripheral blood mononuclear cells of patients with or without EBV diseases. Blood. 2016;127:2007-2017. [PMID: 26744460 DOI: 10.1182/blood-2015-09-672030]

Automated Nucleic Acid Extraction Systems for Detecting Cytomegalovirus and Epstein-Barr Virus Using Real-Time PCR: A Comparison Study Between the QIAsymphony RGQ and QIAcube Systems

BACKGROUND

Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) are increasingly important in immunocompromised patients. Nucleic acid extraction methods could affect the results of viral nucleic acid amplification tests. We compared two automated nucleic acid extraction systems for detecting CMV and EBV using real-time PCR assays.

METHODS

One hundred and fifty-three whole blood (WB) samples were tested for CMV detection, and 117 WB samples were tested for EBV detection. Viral nucleic acid was extracted in parallel by using QIAsymphony RGQ and QIAcube (Qiagen GmbH, Germany), and real-time PCR assays for CMV and EBV were performed with a Rotor-Gene Q real-time PCR cycler (Qiagen). Detection rates for CMV and EBV were compared, and agreements between the two systems were analyzed.

RESULTS

The detection rate of CMV and EBV differed significantly between the QIAsymphony RGQ and QIAcube systems (CMV, 59.5% [91/153] vs 43.8% [67/153], P=0.0005; EBV, 59.0% [69/117] vs 42.7% [50/117], P=0.0008). The two systems showed moderate agreement for CMV and EBV detection (kappa=0.43 and 0.52, respectively). QIAsymphony RGQ showed a negligible correlation with QIAcube for quantitative EBV detection. QIAcube exhibited EBV PCR inhibition in 23.9% (28/117) of samples.

CONCLUSIONS

Automated nucleic acid extraction systems have different performances and significantly affect the detection of viral pathogens. The QIAsymphony RGQ system appears to be superior to the QIAcube system for detecting CMV and EBV. A suitable sample preparation system should be considered for optimized nucleic acid amplification in clinical laboratories.

PD1 blockade with pembrolizumab is highly effective in relapsed or refractory NK/T-cell lymphoma failing l-asparaginase

Natural killer (NK)/T-cell lymphomas failing L-asparaginse regimens have no known salvage and are almost invariably fatal. Seven male patients with NK/T-cell lymphoma (median age, 49 years; range, 31-68 years) for whom a median of 2 (range, 1-5) regimens (including l-asparaginase regimens and allogeneic hematopoietic stem-cell transplantation [HSCT] in 2 cases) failed were treated with the anti-programmed death 1 (PD1) antibody pembrolizumab. All patients responded, according to various clinical, radiologic (positron emission tomography), morphologic, and molecular (circulating Epstein-Barr virus [EBV] DNA) criteria. Two patients achieved complete response (CR) in all parameters. Three patients achieved clinical and radiologic CRs, with two having molecular remission (undetectable EBV DNA) but minimal EBV-encoded RNA-positive cells in lesions comprising predominantly CD3⁺CD4⁺ and CD3⁺CD8⁺ T cells (which ultimately disappeared, suggesting they represented pseudoprogression) and one having detectable EBV DNA despite morphologic CR. Two patients achieved partial response (PR). After a median of 7 (range, 2-13) cycles of pembrolizumab and a follow-up of a median of 6 (range, 2-10) months, all five CR patients were still in remission. The only adverse event was grade 2 skin graft-versus-host disease in one patient with previous allogeneic HSCT. Expression of the PD1 ligand was strong in 4 patients (3 achieving CR) and weak in 1 (achieving PR). PD1 blockade with pembrolizumab was a potent strategy for NK/T-cell lymphomas failing l-asparaginase regimens.

Quantification of BK Virus Standards by Quantitative Real-Time PCR and Droplet Digital PCR Is Confounded by Multiple Virus Populations in the WHO BKV International Standard

BACKGROUND

The WHO recently released a BK virus (BKV) international standard. This study evaluated the WHO international standard and commercially available BKV standards by quantitative real-time PCR (qPCR) and droplet digital PCR (ddPCR).

METHODS

WHO, Exact Diagnostics, Acrometrix, and Zeptometrix BKV standards were tested by qPCR and ddPCR. Two preparations of NIST BKV clones were also tested. Nucleic acid was extracted with the Roche MP96 and MPLC, followed by quantification in duplicate. To resolve discrepancies, we sequenced the WHO and NIST materials.

RESULTS

Manufacturers' expected copies/mL were close to WHO IU/mL: linear regression of qPCR data revealed 1.12 Exact copies/IU, 0.76 Acrometrix copies/IU, and 0.70 Zeptometrix copies/IU. For ddPCR, similar concentrations were measured when either the VP1 region or the T region was targeted, and concentrations were almost 2-fold higher when both regions were targeted simultaneously. ddPCR results for the VP1 and T regions were similar for all commercial standards, but targeting the T region of the WHO standard led to a 4-fold lower result than the VP1 region. Next-generation sequencing revealed no primer or probe mismatches. However, large differences in coverage across the WHO standard and junctional reads were observed, indicating subpopulations of the WHO standard with deletions in the T region.

CONCLUSIONS

BKV standards showed concordance among providers, but the WHO standard contains subpopulations of viruses with various deletions in the T region. PCR results will vary depending on which region of the WHO standard is targeted.

Diagnosis and management of extranodal NK/T cell lymphoma nasal type

INTRODUCTION

Extranodal NK/T-cell lymphoma nasal type is a distinct clinicopathologic entity. The most common initial site of presentation is the nasopharyngeal area, but non-nasals sites including the skin and the gastrointestinal tract may be affected.

AREAS COVERED

The diagnosis and management of NK/T-cell lymphoma is discussed, based on a literature search on PubMed. NK/T-cell lymphoma are typically positive for CD3 (cytoplasmic), CD56, cytotoxic markers (granzyme B, TIA1) and Epstein Barr virus (EBV). Plasma EBV DNA is an accurate surrogate biomarker for lymphoma load. For stage I/II nasal lymphoma, a combination of chemotherapy and radiotherapy yields the best results. Concomitant chemoradiotherapy and sequential chemotherapy and radiotherapy give similar response rates and survivals. For stage III/IV nasal lymphoma and non-nasal lymphomas, chemotherapy is the mainstay of treatment. Conventional anthracycline-based regimens are ineffective. Recommended chemotherapy protocols are based on the use of L-asparaginase combined with other effective drugs. Durable remission can be expected in at least 60% of patients irrespective of stage. Prognostically models based on clinicopathologic parameters and EBV DNA load are useful in stratification of patients for therapy. Expert commentary: Current treatment leads to long-term survival in a significant proportion of patients. For relapsed patients, novel strategies are needed.

Multicenter Evaluation of Whole-Blood Epstein-Barr Viral Load Standardization Using the WHO International Standard

The first WHO international standard for Epstein-Barr virus (EBV) (WHO EBV standard) for nucleic acid amplification technology (NAT)-based assays was commercialized in January 2012 by the National Institute for Biological Standards and Control. In the study reported here, we compared whole-blood EBV DNA load (EDL) results from 12 French laboratories for seven samples (Quality Controls for Molecular Diagnostics 2013 proficiency panel) in order to determine whether expression in international units reduces interlaboratory variability in whole-blood EDLs. Each testing laboratory used a conversion factor to convert EDL results from copies per milliliter to international units per milliliter. This conversion factor was calculated from the WHO EBV standard according to the protocol described in this study (nine laboratories) or the recommendations of the PCR kit suppliers (three laboratories). The interlaboratory variability in whole-blood EDL results was reduced after standardization of the results using the WHO EBV standard. For the seven samples tested, standard deviations (SD) ranged from 0.41 to 0.55 when the results were expressed in log copies per milliliter, whereas the SD ranged from 0.17 to 0.32 when results were given in log international units per milliliter. Comparing the variance data (F test), we showed that the dispersion of whole-blood EDL results was significantly lower when they were expressed in log international units per milliliter (P < 0.001 for six of seven samples and P < 0.05 for one sample with a low mean EDL of 2.62 log IU/ml). This study showed that the use of the WHO EBV standard could improve the homogeneity of whole-blood EDL results between laboratories as well as the monitoring of patients at high risk of posttransplant lymphoproliferative disorders or other EBV-associated diseases.