Expansion of EBV latent membrane protein 2a specific cytotoxic T cells for the adoptive immunotherapy of EBV latency type 2 malignancies: influence of recombinant IL12 and IL15

ABT-737 promotes the dislocation of ER luminal proteins to the cytosol, including pseudomonas exotoxin

Impaired apoptosis is often a key element in tumor development. Therefore, drugs mimicking prosurvival antagonists offer promise as cancer therapeutics. When ABT-737, a BH3-only mimetic, was added to KB3-1 human cervical adenocarcinoma cells, we noted an induction of an endoplasmic reticulum (ER) stress response and the dislocation of ER luminal proteins, including chaperones, to the cell cytosol. Furthermore, when immunotoxin (antibody-toxin chimeric molecule) and ABT-737 combinations were added to cells, there was enhanced toxin-mediated inhibition of protein synthesis, consistent with enhanced translocation of toxin to the cytosol. A similar enhancement was not seen with thapsigargin, suggesting that ER stress alone was not responsible for enhanced translocation. Cytosol preparations from ABT-737-treated but not from thapsigargin-treated cells revealed the presence of greater amounts of processed 37-kDa toxin fragment compared with the addition of immunotoxin alone. As early as 4 hours after the addition of ABT-737 and immunotoxin, there was release of mitochondrial cytochrome c and activation of caspase-3/7 indicating that the combination caused apoptotic cell death. These results were reflected in decreased cellular ATP levels that were noted with combinations of ABT-737 and immunotoxin but not with either agent alone or with combinations of thapsigargin and immunotoxin. We conclude that ABT-737 increases ER permeability, promoting the dislocation of toxin from the ER to the cytosol resulting in early apoptotic cell death. These mechanistic insights suggest why this class of BH3-only mimetic synergizes in a particular way with Pseudomonas exotoxin-based immunotoxins.

Strategies to prevent EBV reactivation and posttransplant lymphoproliferative disorders (PTLD) after allogeneic stem cell transplantation in high-risk patients

Epstein-Barr virus (EBV)-associated postallogeneic stem cell transplantation (SCT) lymphoproliferative disorder (PTLD) is often life threatening. The risk of EBV reactivation is highest in older patients, T cell-depleted SCT (in vivo or vitro), and in unrelated or mismatched SCT. Cumulative numbers of patients with EBV reactivation and PTLD are rising as more patients at high risk for EBV reactivation and PTLD are receiving allo-SCT. Novel but easily applicable strategies are needed to prevent EBV reactivation and PTLD to serve the needs of the increasingly enlarging population of high-risk SCT recipients across the globe.

In vitro anti-tumor immune response induced by dendritic cells transfected with EBV-LMP2 recombinant adenovirus

Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) is a high-incidence tumor in southern China. Latent membrane proteins 2 (LMP2) is a subdominant antigen of EBV. The present study was to develop a dendritic cells (DCs)-based cancer vaccine (rAd-LMP2-DC) and to study its biological characteristics and its immune functions. Our results showed that LMP2 gene transfer did not alter the typical morphology of mature DC, and the representative phenotypes of mature DC (CD80, CD83, and CD86) were highly expressed in rAd-LMP2-DCs. The expression of LMP2 in rAd-LPM2-DCs was about 84.54%, which suggested efficient gene transfer. Transfected DCs markedly increased antigen-specific T-cell proliferation. The specific cytotoxicity against NPC cell was significantly higher than that in controls (p < 0.05), and enhanced with increased stimulations by transfected DCs. In addition, phenotypic analysis demonstrated that the LMP2-specific CTLs consisted of both CD4(+) and CD8(+) T cells. These results showed that development of DC-based vaccine by transfection with malignancy-associated virus antigens could elicit potent CTL response and provide a potential strategy of immunotherapy for EBV-associated NPC.

Epstein–Barr virus: the future for screening, treatment and monitoring of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is often not diagnosed until an advanced stage of the disease, and has a poor 5-year survival with current therapies. Thus, screening programs to identify high-risk patients at early disease stages are essential to improve patient outcomes, most likely through using Epstein–Barr virus (EBV) DNA monitoring in conjunction with tumor-specific markers. EBV-specific cytotoxic T lymphocytes (CTLs) have been utilized successfully for long-term regression of EBV-associated B-cell lymphomas, such as post-transplant lymphoproliferative disease. This strategy has recently been adapted to raise latent membrane proteins 1 and 2, and EBV nuclear antigen 1-specific CD8+ and CD4+ T cells to target EBV proteins expressed in NPC tumors. Future challenges will be focused on developing multiple-target therapies, including improving CTL persistence and tumor specificity. Understanding the role of EBV infection and protein expression in NPC will be pivotal in the development of screening protocols and novel treatments, including vaccines.

Technology insight: Applications of emerging immunotherapeutic strategies for Epstein-Barr virus-associated malignancies

The Epstein-Barr virus (EBV) is uniquely associated with a broad range of human malignancies. In spite of their diverse cellular origin, most of these malignancies share common features, including the expression of either some or all of the EBV latent proteins, which can be potentially exploited for immune-based therapies. Here we discuss new and emerging strategies to manipulate the immune response to specifically boost T-cell immunity towards viral proteins that are expressed in EBV-associated malignancies. These strategies are used either alone or as an adjuvant therapy in combination with chemotherapy and/or monoclonal antibodies. Overall, this strategy may serve as a new paradigm for the successful multi-modality treatment of malignancies.

Epstein-Barr virus in human malignancy: a special reference to Epstein-Barr virus associated gastric carcinoma

Epstein-Bar virus (EBV), a human herpesvirus, establishes a life-long persistent infection in 90 approximately 95% of human adult population worldwide. EBV is the etiologic agent of infectious mononucleosis, and EBV is associated with a variety of human malignancy including lymphoma and gastric carcinoma. Recently, EBV has been classified as group 1 carcinogen by the WHO International Agency for Research on Cancer. Evidence is presented which suggests that failures of the EBV-specific immunity may play a role in the pathogenesis of EBV-associated malignancy. At present, the precise mechanisms by which EBV transforms B lymphocytes have been disclosed. Encouragingly, they have had enough success so far to keep them enthusiastic about novel therapeutic trial in the field of EBV-associated lymphoma. However, information on EBV-associated gastric carcinoma is still at dawn. This article reviews EBV biology, immunological response of EBV infection, unique oncogenic property of EBV, peculiarity of EBV-associated gastric carcinoma, and lastly, EBV-targeted therapy and vaccination.

Treatment options for post-transplant lymphoproliferative disorder and other Epstein-Barr virus-associated malignancies

Epstein-Barr virus (EBV) is associated with a range of malignancies that largely arise from a defect in EBV-specific cytotoxic T lymphocyte (CTL) immunity and function. Much work has focused on the reconstitution of CTL immunity to EBV in transplant patients, in whom immunosuppression modalities render them susceptible to post-transplant lymphoproliferative disease (PTLD). Adoptive transfer of autologous CTLs is effective at both preventing and curing PTLD in solid organ transplant recipients and can produce a long-term memory response and protection against recurring disease. In this review, the benefits and restrictions of administering EBV-specific CTLs for the treatment of PTLD are discussed and compared with emerging therapies including the generation of allogeneic human leukocyte antigen-matched CTL banks and the anti-CD20 monoclonal antibody therapy, MabThera. Furthermore, studies involving other EBV-associated disorders have described the potential benefit of adoptive transfer of EBV-specific CTLs for Hodgkin's disease, nasopharyngeal carcinoma, chronic active EBV infection, and Burkitt's lymphoma. The challenges of tailor-making therapies for individual diseases and EBV antigen expression latencies are highlighted, in addition to considering vaccination strategies for optimal treatment.

Epstein-Barr virus: 40 years on

Epstein-Barr virus (EBV) was discovered 40 years ago from examining electron micrographs of cells cultured from Burkitt's lymphoma, a childhood tumour that is common in sub-Saharan Africa, where its unusual geographical distribution - which matches that of holoendemic malaria -indicated a viral aetiology. However, far from showing a restricted distribution, EBV - a gamma-herpesvirus - was found to be widespread in all human populations and to persist in the vast majority of individuals as a lifelong, asymptomatic infection of the B-lymphocyte pool. Despite such ubiquity, the link between EBV and 'endemic' Burkitt's lymphoma proved consistent and became the first of an unexpectedly wide range of associations discovered between this virus and tumours.