A novel latent membrane 2 transcript expressed in Epstein-Barr virus–positive NK- and T-cell lymphoproliferative disease encodes a target for cellular immunotherapy

Abstract

IntroductionExpression of viral proteins in Epstein-Barr virus (EBV)-associated tumors has allowed specific therapeutic targeting of such antigens with cellular immunotherapies. This is best exemplified by the highly immunogenic lymphoproliferations arising in the T cell-compromised host after allogeneic organ or hematopoietic stem cell transplantation (posttransplant lymphoproliferative disease; PTLD), 1 which express the full complement of EBV latent antigens as seen in lymphoblastoid cell lines (LCLs) generated by EBV infection of B lymphocytes in vitro. 2 A more restricted pattern of EBV latent gene expression is manifest in malignancies such as Hodgkin lymphoma (HL). The so-called Latency II characteristic of these tumors confines expression of EBV-encoded proteins to Epstein-Barr virus nuclear antigen 1 (EBNA1), latent membrane protein 1 (LMP1), LMP2A, and LMP2B. This has presented a greater challenge for clinicians hoping to target such tumors with antigen-specific adoptive T-cell therapy, because these Latency II viral proteins are significantly less immunogenic than the additional Latency III viral antigens, particularly EBNA3A, EBNA3B, and EBNA3C, expressed in PTLD. 2 Cytotoxic T-cell lines (CTLs) generated by in vitro stimulation with LCLs contain low frequencies of T cells specific for LMP2, LMP1, and EBNA1, with accordingly suboptimal clinical efficacy against HL. 3 To address this, investigators have recently focused on skewing the EBVspecific CTL response by an in vitro system of LMP2 overexpression in antigen-presenting cells resulting in an expansion of polyclonal populations of both CD4 ϩ and CD8 ϩ effectors specific for LMP2. 4 This approach has achieved sustained tumor responses (including some complete responses) in patients with relapsed/ refractory HL, with evidence of in vivo expansion and penetration to tumor sites of LMP2-specific T cells. 5 EBV-associated malignancies of natural killer (NK) and T-cell origin are also thought to display a 'Latency II' pattern of EBV gene expression. Extra-nodal NK/T-cell lymphoma (ENKTL) is an aggressive malignancy, occurring at a median age of 50 years and most commonly presenting in the upper-aerodigestive tract. 6 EBV is invariably present within the malignant cells in all cases of ENKTL, irrespective of geographical origin. 7 The clonal and episomal form of EBV in tumor biopsy material 8 implicates a pathogenic role for the virus in the early stages of lymphomagenesis. Although most reports suggest that EBV antigen expression in ENKTL is of a Latency II type, it should be noted that, when expressed, LMP1 protein is usually evident in a subpopulation of malignant cells, while detection of LMP2 in tumor tissue has only been shown at the mRNA level. 9 Also recognized within the Submitted June 23, 2010; accepted July 22, 2010. Prepublished online as Blood First Edition paper, July 29, 2010; DOI 10.1182 DOI 10. /blood-2010 An Inside Blood analysis of this article appears at the front of this issue.The online version of this article contains a data supple...

Expression of Epstein-Barr Virus–Encoded Proteins in Extranodal NK/T-cell Lymphoma, Nasal Type (ENKL): Differences in Biologic and Clinical Behaviors of LMP1-Positive and -Negative ENKL

“…The detection frequency was lower for LMP2A than for LMP1. Fox and colleagues recently reported the existence of a novel LMP2A protein derived from alternatively spliced mRNA in ENKL cells (24). Besides sensitivity, the 2 antibodies used may fail to detect the protein due to different immunogenicity.…”

T-Cell Responses to EBV

“…Although no LMP2 protein or mRNA could be detected in ENKTL cell lines, these cells were nevertheless efficiently recognised and killed by LMP2-specific CD8+ T-cell clones (Fox et al 2010). This apparent paradox was resolved by the identification of a novel LMP2 mRNA transcript expressed from a different promoter that could not be detected by the standard molecular assays in use at the time but still contained the majority of T-cell epitopes.…”

Clinical implications of plasma Epstein-Barr virus DNA in early-stage extranodal nasal-type NK/T-cell lymphoma patients receiving primary radiotherapy

“…Plasma EBV-DNA levels may be used as a stratification factor at presentation and during radiotherapy to identify high-risk patients who may benefit from early systemic therapy or EBV-targeted therapy. 19,45,46 Recent studies have demonstrated that L-asparaginase or bortezomib show promising antitumor activity in T-cell lymphomas and EBV-related NKTCL. 19,44,[47][48][49] Thus, the integration of innovative systemic therapies as well as appropriate radiotherapy for patients with high baseline EBV-DNA levels or detectable EBV-DNA levels after treatment may further improve the long-term prognosis of these patients.…”