Reactivation of latent Epstein-Barr virus by methotrexate: a potential contributor to methotrexate-associated lymphomas

Lymphoproliferative disorders in patients with rheumatoid arthritis in the era of widespread use of methotrexate: A review of the literature and current perspective

Lymphoproliferative disorders (LPD) in patients receiving methotrexate (MTX) have gained strong attention. In this article, I reviewed the basic and clinical findings of this issue. Patients with RA possess a high risk of lymphoma, but epidemiological evidence showing an association between the use of MTX and lymphoma is still limited. Rapid regression of LPD after stopping MTX in patients with RA strongly suggests that there is a causative relationship. Genetic predisposition, accumulated inflammation, impaired generation of Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes, effects of MTX on the regulation of EBV genes, and low hypermethylation of apoptosis-related genes are relevant to the development of LPD and rapid regression after cessation of MTX. The clinical and histological characteristics of LPD in RA patients who are treated with MTX have been established, and recent data indicate that initial cessation of MTX and watchful waiting to observe an increase in peripheral lymphocyte counts have a therapeutic value. In advanced cases, various chemotherapy regimens are used, and consultation with hematologists is recommended to select the optimal treatment. There is no consensus on the treatment of RA after development of LPD, and long-term observation is necessary to investigate the safety of disease-modifying antirheumatic drugs in these patients.

ATM supports gammaherpesvirus replication by attenuating type I interferon pathway

Ataxia-Telangiectasia mutated (ATM) kinase participates in multiple networks, including DNA damage response, oxidative stress, and mitophagy. ATM also supports replication of diverse DNA and RNA viruses. Gammaherpesviruses are prevalent cancer-associated viruses that benefit from ATM expression during replication. This proviral role of ATM had been ascribed to its signaling within the DNA damage response network; other functions of ATM have not been considered. In this study increased type I interferon (IFN) responses were observed in ATM deficient gammaherpesvirus-infected macrophages. Using a mouse model that combines ATM and type I IFN receptor deficiencies we show that increased type I IFN response in the absence of ATM fully accounts for the proviral role of ATM during gammaherpesvirus replication. Further, increased type I IFN response rendered ATM deficient macrophages more susceptible to antiviral effects of type II IFN. This study identifies attenuation of type I IFN responses as the primary mechanism underlying proviral function of ATM during gammaherpesvirus infection.

Epstein-Barr virus and rheumatoid arthritis

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases, with a 0.5% worldwide prevalence. The cause of RA remains unknown, however both genetic and environmental factors may contribute to its development. Among these is the Epstein-Barr virus (EBV). Here, we discuss several aspects of the close relationship between EBV and RA. Patients with RA have impaired control of EBV infection. Indeed, they have high titres of antibodies against EBV antigens. Their peripheral blood T lymphocytes are less efficient at controlling the outgrowth of EBV-infected B cells. RA patients have more EBV-infected B cells than normal controls, leading to a 10-fold systemic EBV overload. Post-transplant lymphoproliferative disorder (PTLPD) is a polyclonal EBV-positive B lymphocyte proliferation, which can evolve into an EBV-positive B cell lymphoma. RA patients also have an increased risk of developing EBV-associated lymphoproliferative disorder (LPD). Hence the need to monitor EBV load when treating RA patients with immunosuppressors. EBV, a widespread virus, highly recognized by antibodies but never eliminated, is an ideal candidate to trigger chronic immune complex disease. Anti-EBV antibody responses should be considered as one of the chronic autoantibody responses linked to the development of RA, in the same way as anti-citrullinated protein antibodies.

Methotrexate-associated primary hepatic malignant lymphoma following hepatectomy: A case report

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Primary hepatic lymphoma is difficult to diagnose preoperatively.

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MTX use encouraged MTX-related ML.

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In MTX-related MLs, withdrawing MTX had a therapeutic effect.

Introduction

Recently, immunosuppressant-associated malignant lymphoma (ML) cases have been increasing along with the development of several effective immunosuppressant drugs for rheumatoid arthritis (RA). Among methotrexate (MTX)-associated lymphoproliferative disorders, primary hepatic lymphoma (PHL) in patients with RA following surgical resection has not been reported previously.

Presentation of case

A 65-year-old woman who is a hepatitis B virus carrier with a history of RA was admitted. MTX was introduced seven years prior as an RA treatment. Her laboratory data showed no elevation of several tumor markers, and liver function test results were normal. On contrasted computed tomography (CT) scanning, a slightly enhanced tumor was detected at the early phase, and tumor staining was sustained at the delayed phase. Further, subsegmentectomy of the S6 was performed. The pathological diagnosis was diffuse large B-cell lymphoma. However, positron emission tomography-CT and bone marrow aspiration sample showed no resident sign of ML.

Discussion

Diagnosis of PHL before surgery is difficult. If the mass lesion was solitary and had a certain degree of size, then resection could be performed for its treatment and diagnosis. The treatment for ML requires a diagnosis of the subtypes to select a therapeutic agent and determine the prognosis. Once a precise preoperative diagnosis was made, withdrawing MTX could be the first treatment in case of MTX-related ML.

Conclusion

Long-term usage of immunosuppressant drugs could cause proliferative ML. Considering the increasing occurrence of MTX-related ML, withdrawing MTX should be considered, especially in patients with long-term immunosuppressant usage for RA.

Lenalidomide, Thalidomide, and Pomalidomide Reactivate the Epstein-Barr Virus Lytic Cycle through Phosphoinositide 3-Kinase Signaling and Ikaros Expression

PURPOSE

Lenalidomide, thalidomide, and pomalidomide (LTP) are immunomodulatory agents approved for use in multiple myeloma, but in some settings, especially with alkylating agents, an increase in Hodgkin lymphoma and other secondary primary malignancies (SPM) has been noted. Some of these malignancies have been linked to Epstein-Barr virus (EBV), raising the possibility that immunomodulatory drugs disrupt latent EBV infection.

EXPERIMENTAL DESIGN

We studied the ability of LTP to reactivate latently infected EBV-positive cell lines in vitro and in vivo, and evaluated the EBV viral load in archived serum samples from patients who received a lenalidomide, thalidomide, and dexamethasone (LTD) combination.

RESULTS

Treatment of EBV-infected B-cell lines with LTP at physiologically relevant concentrations induced the immediate early gene BZLF1, the early gene BMRF1, and the late proteins VCA and BCFR1. This occurred in the potency order pomalidomide > lenalidomide > thalidomide, and the nucleoside analogue ganciclovir enhanced the cytotoxic effects of lenalidomide and pomalidomide in Burkitt lymphoma cells in vitro and in vivo EBV reactivation was related to PI3K stimulation and Ikaros suppression, and blocked by the PI3Kδ inhibitor idelalisib. Combinations of lenalidomide with dexamethasone or rituximab increased EBV reactivation compared with lenalidomide alone and, importantly, lenalidomide with melphalan produced even greater reactivation.

CONCLUSIONS

We conclude LTP may reactivate EBV-positive resting memory B cells thereby enhancing EBV lytic cycle and host immune suppression. Clin Cancer Res; 22(19); 4901-12. ©2016 AACR.

Clinical manifestations of autoimmune disease-related non-Hodgkin lymphoma: a Korean single-center, retrospective clinical study

BACKGROUND/AIMS

Recently, large cohort studies regarding associations between autoimmune disease and lymphomas have been reported in a few Western countries. However, Asian data concerning autoimmune-related lymphomas are limited. Therefore, we evaluated the clinical characteristics and prognostic factors of patients with autoimmune disease-related non-Hodgkin lymphoma (NHL) in a single center in Korea.

METHODS

We analyzed the data from 11 patients with autoimmune-related NHL. Patients were categorized into two groups, those with rheumatoid arthritis (RA) and those with non-RA-related NHL. Then patients were re-categorized into a group with methotrexate (MTX) usage and a MTX non-usage group. Histological subtype, MTX duration, autoimmune disease duration, treatment modalities, and other data were collected and analyzed.

RESULTS

Our study revealed that older RA patients have a greater likelihood of occurrence of NHL (p = 0.042). We confirmed that MTX duration and cumulative dose of MTX have no significant correlation with autoimmune disease and NHL (p = 0.073). In the management of autoimmune disease-related NHL, all patients were directly treated with systemic chemotherapy instead of employing a wait and watch approach. Overall survival (OS) and progression-free survival (PFS) in all autoimmune disease-related NHL were 100% and 87.5%, with no treatment-related mortality during the 2-year follow-up period of our study.

CONCLUSIONS

Our study suggests that patients with RA-NHL are characterized by older age at onset compared to those with non-RA-NHL. Also considering of OS and PFS, intensive treatment strategy instead of delayed watchful managements may be required for autoimmune disease-related NHL including of old age group.

A case of multiple hepatic lesions associated with methotrexate-associated lymphoproliferative disorder

Patients receiving methotrexate (MTX) for the treatment of autoimmune disease are at a high risk of developing lymphoproliferative disorders (LPD), the so-called methotrexate-associated lymphoproliferative disorders (MTX-LPD). We recently performed abdominal ultrasonography (US) in a patient with rheumatoid arthritis (RA) who had developed hepatic dysfunction during the course of MTX therapy; the examination revealed multiple well-demarcated hepatic tumors with slightly irregular borders, the largest one measuring 9 cm in diameter. In view of the finding of portal and hepatic veins perforating the tumor, we suspected a diagnosis of malignant lymphoma and performed a hepatic tumor biopsy. Histopathological examination of the biopsy specimens revealed a diagnosis of diffuse large B-cell lymphoma, and we made a final diagnosis of MTX-LPD. MTX treatment was discontinued, which resulted in rapid resolution of the lesions. Resolution of MTX-LPD can be obtained just by discontinuation of MTX treatment. In patients receiving MTX therapy who are found to have hepatic tumors perforated by the portal vein and/or hepatic vein on abdominal US, it is advisable to perform hepatic tumor biopsy to facilitate differential diagnosis of MTX-LPD and enable a definite diagnosis.

Gastric adenocarcinoma microRNA profiles in fixed tissue and in plasma reveal cancer-associated and Epstein-Barr virus-related expression patterns

MicroRNA expression in formalin-fixed paraffin-embedded tissue (FFPE) or plasma may add value for cancer management. The GastroGenus miR Panel was developed to measure 55 cancer-specific human microRNAs, Epstein-Barr virus (EBV)-encoded microRNAs, and controls. This Q-rtPCR panel was applied to 100 FFPEs enriched for adenocarcinoma or adjacent non-malignant mucosa, and to plasma of 31 patients. In FFPE, microRNAs upregulated in malignant versus adjacent benign gastric mucosa were hsa-miR-21, -155, -196a, -196b, -185, and -let-7i. Hsa-miR-18a, 34a, 187, -200a, -423-3p, -484, and -744 were downregulated. Plasma of cancer versus non-cancer controls had upregulated hsa-miR-23a, -103, and -221 and downregulated hsa-miR-378, -346, -486-5p, -200b, -196a, -141, and -484. EBV-infected versus uninfected cancers expressed multiple EBV-encoded microRNAs, and concomitant dysregulation of four human microRNAs suggests that viral infection may alter cellular biochemical pathways. Human microRNAs were dysregulated between malignant and benign gastric mucosa and between plasma of cancer patients and non-cancer controls. Strong association of EBV microRNA expression with known EBV status underscores the ability of microRNA technology to reflect disease biology. Expression of viral microRNAs in concert with unique human microRNAs provides novel insights into viral oncogenesis and reinforces the potential for microRNA profiles to aid in classifying gastric cancer subtypes. Pilot studies of plasma suggest the potential for a noninvasive addition to cancer diagnostics.

Monitoring of Epstein-Barr virus load and killer T cells in patients with juvenile idiopathic arthritis treated with methotrexate or tocilizumab

OBJECTIVES

Methotrexate (MTX) is used for the treatment of polyarticular juvenile idiopathic arthritis (JIA), and an anti-interleukin-6 receptor monoclonal antibody (tocilizumab: TCZ) is also used and added for the treatment of intractable JIA. It has been reported that MTX might induce Epstein-Barr virus (EBV)-associated lymphoma, but the discussion about the effect of MTX and/or TCZ against reactivation of EBV in pediatric patients has been incomplete.

METHODS

The EBV loads in four polyarticular JIA and three systemic arthritis JIA patients treated with MTX and/or TCZ, and the percentage of EBV-specific killer T cells (EBV-CTLs) in some patients were prospectively monitored.

RESULTS

No patients had EBV-associated symptoms during the observation period. EBV loads in all patients were not significantly increased, and the levels of EBV loads were the same as EBV-seropositive healthy children following the administration of MTX and/or TCZ. EBV-CTLs were detectable during the observation period, but some patients had slightly low levels of EBV-CTLs.

CONCLUSION

Treatment with MTX and/or TCZ did not severely affect EBV load and prevent induction of EBV-CTLs in JIA patients.

Diagnostic and therapeutic challenges of EBV-positive mucocutaneous ulcer: a case report and systematic review of the literature

BACKGROUND

Epstein-Barr virus-positive mucocutaneous ulcer (EBVMCU) is a recently recognized B cell lymphoproliferative disorder that is driven by latent EBV infection and causes discrete ulcerations in the oropharynx, gastrointestinal tract, and skin. Local attenuation of immunosurveillance associated with iatrogenic immunosuppressant use, primary immunodeficiency, or age-associated immunosenescence has been implicated as a predisposing factor. This disorder is likely under reported, as it was only first defined in 2010 and shares histological features with other B-cell proliferative neoplasms. The first case series that described EBVMCU suggested that EBVMCU is generally self-limited and is likely to resolve without treatment. Since that publication, additional cases have been reported that describe a more heterogeneous clinical course, often requiring aggressive therapy. We now systematically review all published cases of EBVMCU and detail a case of aggressive and progressive EBVMCU, including diagnostic and management challenges, as well as successful treatment with radiation therapy.

CASE PRESENTATION

A forty-nine year old woman presented with painful and debilitating multifocal oral EBVMCU that initially responded to four weekly doses of rituximab. Her disease relapsed within 3 months and continued to progress and cause significant morbidity. She was successfully treated with local external beam radiation therapy of 30 Gy in 15 fractions, with duration of response of at least 6 months.

CONCLUSIONS

We suggest that although many patients with EBVMCU experience a self-limited course, for others EBVMCU can be a debilitating, persistent disorder that requires aggressive therapy to prevent disease progression. CD20- and CD30-directed antibody therapy, local radiation therapy, local surgical excision, systemic chemotherapy, and a combination of these therapies have all been successfully used to treat EBVMCU with high rates of durable clinical remission. As EBVMCU is not currently included in the 2008 WHO classification of lymphoproliferative disorders and no evidence-based guidelines or expert opinions have been proposed to guide therapy, this case report and systematic review provides a foundation on which to guide therapeutic decisions.

Clinical Features and Outcomes of Patients With Symptomatic Kaposi Sarcoma Herpesvirus (KSHV)-associated Inflammation: Prospective Characterization of KSHV Inflammatory Cytokine Syndrome (KICS)

BACKGROUND

Kaposi sarcoma herpesvirus (KSHV) is the cause of Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and a form of Castleman disease (KSHV-MCD). Recently a KSHV-associated inflammatory cytokine syndrome (KICS) distinct from KSHV-MCD was reported.

METHODS

We prospectively characterized the clinical, laboratory, virologic and immunologic features of KICS by evaluating symptomatic adults with KSHV using a prespecified definition. These features and overall survival were compared with controls from 2 prospectively characterized human immunodeficiency virus (HIV)-infected cohorts, including 1 with KSHV coinfection.

RESULTS

All 10 KICS subjects were HIV infected males; 5 had HIV viral load (VL) suppressed <50 copies mL (median 72, range <50-74 375); all had KS and 2 also had PEL. All had multiple severe symptoms attributable to KICS: median number of symptoms 8 (6-11), median grade of worst symptom 3 (2-4). These included gastrointestinal disturbance (present in 9); edema (9); respiratory (6); and effusions (5). Laboratory abnormalities included anemia (all); hypoalbuminemia (all) and thrombocytopenia (6). None developed KSHV-MCD; 6 died with median survival from KICS diagnosis 13.6 months. KICS subjects compared with controls had more severe symptoms; lower hemoglobin and albumin; higher C-reactive protein; higher KSHV VL; elevated interleukin (IL)-6 and IL-10; and an increased risk of death (all P < .05). Anemia and hypoalbuminemia at presentation were independently associated with early death.

CONCLUSIONS

KICS subjects demonstrated diverse severe symptoms, a high rate of KSHV-associated tumors, high mortality, and a distinct IL-6/IL-10 signature. KICS may be an important unrecognized cause of morbidity and mortality, including symptoms previously ascribed to HIV. Exploration of KSHV-directed therapy is warranted.

MYC/BCL2 Double-hit Lymphoma in a Patient with Rheumatoid Arthritis Associated with Methotrexate Treatment

Several reports have suggested an increased risk of malignant lymphoma in patients with rheumatoid arthritis treated with methotrexate (MTX). We herein describe the case of a 71-year-old woman with rheumatoid arthritis who developed MYC/BCL2 double-hit lymphoma associated with MTX therapy. She developed a fever and lymphadenopathies over a 2-week period and had elevated levels of soluble IL-2 receptor. Inguinal lymph node and bone marrow biopsies showed diffuse large B cell lymphoma. Fluorescent in situ hybridization revealed MYC and BCL2 gene rearrangements in her lymphoma cells. Accordingly, a diagnosis of MYC/BCL2 double-hit lymphoma was made. This is the first reported case of a double-hit lymphoma associated with MTX therapy.

Lymphoproliferative disorders in inflammatory bowel disease patients on immunosuppression: Lessons from other inflammatory disorders

Immunosuppressive agents, such as thiopurines, methotrexate, and biologics, have revolutionized the treatment of inflammatory bowel disease (IBD). However, a number of case reports, case control studies and retrospective studies over the last decade have identified a concerning link between immunosuppression and lymphoproliferative disorders (LPDs), the oncological phenomenon whereby lymphocytes divide uncontrollably. These LPDs have been associated with Epstein-Barr virus (EBV) infection in which the virus provides the impetus for malignant transformation while immunosuppression hampers the immune system’s ability to detect and clear these malignant cells. As such, the use of immunosuppressive agents may come at the cost of increased risk of developing LPD. While little is known about the LPD risk in IBD, more is known about immunosuppression in the post-transplantation setting and the development of EBV associated post-transplantation lymphoproliferative disorders (PTLD). In review of the PTLD literature, evidence is available to demonstrate that certain immune suppressants such as cyclosporine and T-lymphocyte modulators in particular are associated with an increased risk of PTLD development. As well, high doses of immunosuppressive agents and multiple immunosuppressive agent use are also linked to increased PTLD development. Here, we discuss these findings in context of IBD and what future studies can be taken to understand and reduce the risk of EBV-associated LPD development from immunosuppression use in IBD.

Epstein-Barr Virus (EBV) Tegument Protein BGLF2 Promotes EBV Reactivation through Activation of the p38 Mitogen-Activated Protein Kinase

Epstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus associated with both B cell and epithelial cell malignancies. EBV infection of B cells triggers activation of several signaling pathways that are critical for cell survival, virus latency, and growth transformation. To identify EBV proteins important for regulating cell signaling, we used a proteomic approach to screen viral proteins for AP-1 and NF-κB promoter activity in AP-1- and NF-κB-luciferase reporter assays. We found that EBV BGLF2 activated AP-1 but not NF-κB reporter activity. Expression of EBV BGLF2 in cells activated p38 and c-Jun N-terminal kinase (JNK), both of which are important for mitogen-activated protein kinase (MAPK) signaling. Deletion of the carboxyl-terminal 66 amino acids of BGLF2 reduced the ability of BGLF2 to activate JNK and p38. Expression of BGLF2 enhanced BZLF1 expression in latently EBV-infected lymphoblastoid cell lines, and knockdown of BGLF2 reduced EBV reactivation induced by IgG cross-linking. Expression of BGLF2 induced BZLF1 expression and virus production in EBV-infected gastric carcinoma cells. BGLF2 enhanced BZLF1 expression and EBV production by activating p38; chemical inhibition of p38 and MAPK/ERK kinases 1 and 2 (MEK1/2) reduced expression of BZLF1 and virus production induced by BGLF2. In summary, the EBV tegument protein BGLF2, which is delivered to the cell at the onset of virus infection, activates the AP-1 pathway and enhances EBV reactivation and virus production.

IMPORTANCE

Epstein-Barr virus (EBV) is associated with both B cell and epithelial cell malignancies, and the virus activates multiple signaling pathways important for its persistence in latently infected cells. We identified a viral tegument protein, BGLF2, which activates members of the mitogen-activated protein kinase signaling pathway. Expression of BGLF2 increased expression of EBV BZLF1, which activates a switch from latent to lytic virus infection, and increased production of EBV. Inhibition of BGFL2 expression or inhibition of p38/MAPK, which is activated by BGLF2, reduced virus reactivation from latency. These results indicate that a viral tegument protein which is delivered to cells upon infection activates signaling pathways to enhance virus production and facilitate virus reactivation from latency.

Epstein- Barr Virus: Clinical and Epidemiological Revisits and Genetic Basis of Oncogenesis

Epstein-Barr virus (EBV) is classified as a member in the order herpesvirales, family herpesviridae, subfamily gammaherpesvirinae and the genus lymphocytovirus. The virus is an exclusively human pathogen and thus also termed as human herpesvirus 4 (HHV4). It was the first oncogenic virus recognized and has been incriminated in the causation of tumors of both lymphatic and epithelial nature. It was reported in some previous studies that 95% of the population worldwide are serologically positive to the virus. Clinically, EBV primary infection is almost silent, persisting as a life-long asymptomatic latent infection in B cells although it may be responsible for a transient clinical syndrome called infectious mononucleosis. Following reactivation of the virus from latency due to immunocompromised status, EBV was found to be associated with several tumors. EBV linked to oncogenesis as detected in lymphoid tumors such as Burkitt's lymphoma (BL), Hodgkin's disease (HD), post-transplant lymphoproliferative disorders (PTLD) and T-cell lymphomas (e.g. Peripheral T-cell lymphomas; PTCL and Anaplastic large cell lymphomas; ALCL). It is also linked to epithelial tumors such as nasopharyngeal carcinoma (NPC), gastric carcinomas and oral hairy leukoplakia (OHL). In vitro, EBV many studies have demonstrated its ability to transform B cells into lymphoblastoid cell lines (LCLs). Despite these malignancies showing different clinical and epidemiological patterns when studied, genetic studies have suggested that these EBV- associated transformations were characterized generally by low level of virus gene expression with only the latent virus proteins (LVPs) upregulated in both tumors and LCLs. In this review, we summarize some clinical and epidemiological features of EBV- associated tumors. We also discuss how EBV latent genes may lead to oncogenesis in the different clinical malignancies

Acute Hepatitis E Virus infection with coincident reactivation of Epstein-Barr virus infection in an immunosuppressed patient with rheumatoid arthritis: a case report

Background

Hepatitis E virus (HEV) is the most recently discovered of the hepatotropic viruses, and is considered an emerging pathogen in developed countries with the possibility of fulminant hepatitis in immunocompromised patients. Especially in the latter elevated transaminases should be taken as a clue to consider HEV infection, as it can be treated by discontinuation of immunosuppression and/or ribavirin therapy. To our best knowledge, this is a unique case of autochthonous HEV infection with coincident reactivation of Epstein-Barr virus (EBV) infection in an immunosuppressed patient with rheumatoid arthritis (RA).

Case presentation

A 68-year-old Swiss woman with RA developed hepatitis initially diagnosed as methotrexate-induced liver injury, but later diagnosed as autochthonous HEV infection accompanied by reactivation of her latent EBV infection. She showed confounding serological results pointing to three hepatotropic viruses (HEV, Hepatitis B virus (HBV) and EBV) that could be resolved by detection of HEV and EBV viraemia. The patient recovered by temporary discontinuation of immunosuppressive therapy.

Conclusions

In immunosuppressed patients with RA and signs of liver injury, HEV infection should be considered, as infection can be treated by discontinuation of immunosuppression.

Although anti-HEV-IgM antibody assays can be used as first line virological tools, nucleic acid amplification tests (NAAT) for detection of HEV RNA are recommended – as in our case - if confounding serological results from other hepatotropic viruses are obtained. After discontinuation of immunosuppressive therapy, our patient recovered from both HEV infection and reactivation of latent EBV infection without sequelae.

ATM facilitates mouse gammaherpesvirus reactivation from myeloid cells during chronic infection

Gammaherpesviruses are cancer-associated pathogens that establish life-long infection in most adults. Insufficiency of Ataxia-Telangiectasia mutated (ATM) kinase leads to a poor control of chronic gammaherpesvirus infection via an unknown mechanism that likely involves a suboptimal antiviral response. In contrast to the phenotype in the intact host, ATM facilitates gammaherpesvirus reactivation and replication in vitro. We hypothesized that ATM mediates both pro- and antiviral activities to regulate chronic gammaherpesvirus infection in an immunocompetent host. To test the proposed proviral activity of ATM in vivo, we generated mice with ATM deficiency limited to myeloid cells. Myeloid-specific ATM deficiency attenuated gammaherpesvirus infection during the establishment of viral latency. The results of our study uncover a proviral role of ATM in the context of gammaherpesvirus infection in vivo and support a model where ATM combines pro- and antiviral functions to facilitate both gammaherpesvirus-specific T cell immune response and viral reactivation in vivo.

Anti-TNFα therapy for inflammatory bowel diseases is associated with Epstein-Barr virus lytic activation

Anti-TNFα therapy, known to suppress T-cell immunity, is increasingly gaining popularity for treatment of autoimmune diseases including inflammatory bowel diseases (IBD). T-cell suppression increases the risk of B-cell EBV-lymphoproliferative diseases and lymphomas. Since EBV-lytic activation is essential for development of EBV-lymphomas and there have been reports of EBV-lymphomas in patients treated with anti-TNFα therapy, we investigated if patients treated with anti-TNFα antibodies demonstrate greater EBV-lytic activity in blood. Peripheral blood mononuclear cells from 10 IBD patients solely on anti-TNFα therapy compared to 3 control groups (10 IBD patients not on immunosuppressive therapy, 10 patients with abdominal pain but without IBD, and 10 healthy subjects) were examined for the percentage of T-cells, EBV load and EBV-lytic transcripts. Patients on anti-TNFα therapy had significantly fewer T-cells, greater EBV load, and increased levels of transcripts from EBV-lytic genes of all kinetic classes compared to controls. Furthermore, exposure of EBV-infected B-cell lines to anti-TNFα antibodies resulted in increased levels of BZLF1 mRNA; BZLF1 encodes for ZEBRA, the viral latency-to-lytic cycle switch. Thus, IBD patients treated with anti-TNFα antibodies have greater EBV loads likely due to enhanced EBV-lytic gene expression and anti-TNFα antibodies may be sufficient to activate the EBV lytic cycle. Findings from this pilot study lay the groundwork for additional scientific and clinical investigation into the effects of anti-TNFα therapy on the life cycle of EBV, a ubiquitous oncovirus that causes lymphomas in the setting of immunocompromise.

Post-transplant lymphoproliferative disorders: from epidemiology to pathogenesis-driven treatment

Post-transplant lymphoproliferative disorders (PTLDs) represent the most severe complication of both solid organ and hematopoietic stem cell transplantation. The Epstein-Barr Virus (EBV) is the main driver of PTLD, particularly those occurring early after transplantation. EBV-driven malignancies are associated with selective expression of latent viral proteins, but uncontrolled lytic replication may favor early phases of cell transformation. Besides immunodepression, persistent immune activation and chronic inflammation play an important role in both virus reactivation and expansion of EBV-infected B cells. EBV-induced immortalization requires the expression of telomerase. TERT, the rate-limiting component of the telomerase complex, is central in the switch from the lytic to the latent viral program, and TERT inhibition induces the EBV lytic cycle and cell death. Immunotherapy and combination of EBV lytic cycle inducers with antiviral drugs are promising strategies to improve the treatment of PTLD patients. This review is aimed at providing an update on the intriguing association between EBV and PTLD, mainly focusing on cases arising after kidney and liver transplantation, which account for the vast majority of transplants.

Cross talk between EBV and telomerase: the role of TERT and NOTCH2 in the switch of latent/lytic cycle of the virus

Epstein–Barr virus (EBV)-associated malignancies, as well as lymphoblastoid cell lines (LCLs), obtained in vitro by EBV infection of B cells, express latent viral proteins and maintain their ability to grow indefinitely through inappropriate activation of telomere-specific reverse transcriptase (TERT), the catalytic component of telomerase. Our previous studies demonstrated that high levels of TERT expression in LCLs prevent the activation of EBV lytic cycle, which is instead triggered by TERT silencing. As lytic infection promotes the death of EBV-positive tumor cells, understanding the mechanism(s) by which TERT affects the latent/lytic status of EBV may be important for setting new therapeutic strategies. BATF, a transcription factor activated by NOTCH2, the major NOTCH family member in B cells, negatively affects the expression of BZLF1, the master regulator of viral lytic cycle. We therefore analyzed the interplay between TERT, NOTCH and BATF in LCLs and found that high levels of endogenous TERT are associated with high NOTCH2 and BATF expression levels. In addition, ectopic expression of TERT in LCLs with low levels of endogenous telomerase was associated with upregulation of NOTCH2 and BATF at both mRNA and protein levels. By contrast, infection of LCLs with retroviral vectors expressing functional NOTCH2 did not alter TERT transcript levels. Luciferase reporter assays, demonstrated that TERT significantly activated NOTCH2 promoter in a dose-dependent manner. We also found that NF-κB pathway is involved in TERT-induced NOTCH2 activation. Lastly, pharmacologic inhibition of NOTCH signaling triggers the EBV lytic cycle, leading to the death of EBV-infected cells. Overall, these results indicate that TERT contributes to preserve EBV latency in B cells mainly through the NOTCH2/BAFT pathway, and suggest that NOTCH2 inhibition may represent an appealing therapeutic strategy against EBV-associated malignancies.

Methotrexate-associated lymphoproliferative disorders: management by watchful waiting and observation of early lymphocyte recovery after methotrexate withdrawal

No optimum treatment of iatrogenic immunodeficiency-associated lymphoproliferative disorders due to methotrexate in patients with rheumatoid arthritis (MTX-LPD) has yet been established, although MTX withdrawal is known to have a substantial effect on tumor regression. Here, we retrospectively analyzed 20 cases of MTX-LPD. Tumor shrinkage occurred in 18 of 20 cases, but only following MTX withdrawal. This tumor regression ratio was considerably better than in previous reports, and appeared due to longer "watchful waiting." Lymphocyte recovery at 2 weeks after MTX withdrawal was significantly higher in cases with tumor regression in 1 month than in those without tumor regression (p = 0.001). Median time to maximal efficacy after MTX cessation in cases without chemotherapy was 12 weeks (range 2-76). In conclusion, watchful waiting for a longer period after MTX cessation with observation of early lymphocyte recovery and uninterrupted continuation of other anti-rheumatoid drugs may be an acceptable management plan for MTX-LPD.

LMP1-Induced Sumoylation Influences the Maintenance of Epstein-Barr Virus Latency through KAP1

As a herpesvirus, Epstein-Barr virus (EBV) establishes a latent infection that can periodically undergo reactivation, resulting in lytic replication and the production of new infectious virus. Latent membrane protein-1 (LMP1), the principal viral oncoprotein, is a latency-associated protein implicated in regulating viral reactivation and the maintenance of latency. We recently found that LMP1 hijacks the SUMO-conjugating enzyme Ubc9 via its C-terminal activating region-3 (CTAR3) and induces the sumoylation of cellular proteins. Because protein sumoylation can promote transcriptional repression, we hypothesized that LMP1-induced protein sumoylation induces the repression of EBV lytic promoters and helps maintain the viral genome in its latent state. We now show that with inhibition of LMP1-induced protein sumoylation, the latent state becomes less stable or leakier in EBV-transformed lymphoblastoid cell lines. The cells are also more sensitive to viral reactivation induced by irradiation, which results in the increased production and release of infectious virus, as well as increased susceptibility to ganciclovir treatment. We have identified a target of LMP1-mediated sumoylation that contributes to the maintenance of latency in this context: KRAB-associated protein-1 (KAP1). LMP1 CTAR3-mediated sumoylation regulates the function of KAP1. KAP1 also binds to EBV OriLyt and immediate early promoters in a CTAR3-dependent manner, and inhibition of sumoylation processes abrogates the binding of KAP1 to these promoters. These data provide an additional line of evidence that supports our findings that CTAR3 is a distinct functioning regulatory region of LMP1 and confirm that LMP1-induced sumoylation may help stabilize the maintenance of EBV latency.

IMPORTANCE

Epstein-Barr virus (EBV) latent membrane protein-1 (LMP1) plays an important role in the maintenance of viral latency. Previously, we documented that LMP1 targets cellular proteins to be modified by a ubiquitin-like protein (SUMO). We have now identified a function for this LMP1-induced modification of cellular proteins in the maintenance of EBV latency. Because latently infected cells have to undergo viral reactivation in order to be vulnerable to antiviral drugs, these findings identify a new way to increase the rate of EBV reactivation, which increases cell susceptibility to antiviral therapies.

The role of PI3K/Akt in human herpesvirus infection: From the bench to the bedside

The phosphatidylinositol-3-kinase (PI3K)-Akt signaling pathway regulates several key cellular functions including protein synthesis, cell growth, glucose metabolism, and inflammation. Many viruses have evolved mechanisms to manipulate this signaling pathway to ensure successful virus replication. The human herpesviruses undergo both latent and lytic infection, but differ in cell tropism, growth kinetics, and disease manifestations. Herpesviruses express multiple proteins that target the PI3K/Akt cell signaling pathway during the course of their life cycle to facilitate viral infection, replication, latency, and reactivation. Rare human genetic disorders with mutations in either the catalytic or regulatory subunit of PI3K that result in constitutive activation of the protein predispose to severe herpesvirus infections as well as to virus-associated malignancies. Inhibiting the PI3K/Akt pathway or its downstream proteins using drugs already approved for other diseases can block herpesvirus lytic infection and may reduce malignancies associated with latent herpesvirus infections.

Primary central nervous system lymphoma in a rheumatoid arthritis patient treated with methotrexate: a case report

Background

Rheumatoid arthritis is a systemic inflammatory disease characterized by synovitis and the destruction of articular structures in multiple joints. Methotrexate is recommended as an anchor drug for rheumatoid arthritis treatment to achieve the therapeutic goal of reducing damage to joints and improving clinical score. However, several studies have shown that methotrexate has been associated with the development of lymphoproliferative disorders, namely methotrexate-associated lymphoproliferative disorders. On the other hand, primary central nervous system lymphoma is an aggressive disease with poor prognosis. Both methotrexate-associated lymphoproliferative disorders and primary central nervous system lymphoma are reported to be associated with Epstein-Barr virus.

Case presentation

A Japanese female patient of between 60 and 70 years of age with rheumatoid arthritis was admitted to our hospital because of sudden convulsion and impaired consciousness. Just before admission, she was treated with adalimumab and methotrexate. Contrast-enhanced computed tomography scan showed a densely stained mass with surrounding edema in both frontal lobes and the left nucleus basalis, and enlarged lymph nodes in the right supraclavicular fossa. We performed a biopsy of the right cervical lymph node, but could not establish a histopathological diagnosis. In situ hybridization showed the presence of Epstein Barr virus, therefore we diagnosed this case as methotrexate-associated lymphoproliferative disorders mediated by Epstein Barr virus after considering the drug history of the patient. After we discontinued methotrexate, patient symptoms gradually improved. The masses at both frontal lobes and the left nucleus basalis were gradually regressed.

Conclusion

Since the frequency of methotrexate use and the maximum dosage has been increasing, particular attention should be paid to the development of methotrexate-associated lymphoproliferative disorders in rheumatoid arthritis patients who are treated with methotrexate.

Incidence of malignancy and the risk of lymphoma in Japanese patients with rheumatoid arthritis compared to the general population

OBJECTIVE

Recent advances in the management of patients with rheumatoid arthritis (RA) increased the rates of disease remission and patient life expectancy, while malignancy has become a more common cause of death. Here, we report the incidence of malignancy in a nationwide survey of Japanese patients with RA compared to the general population, focusing on the risk of lymphoma, which often arises in patients with RA.

METHODS

Data on the occurrence of malignancy were collected from patients registered in a nationwide Japanese cohort database, the National Database of Rheumatic Diseases by iR-net in Japan, from 2003 to 2012. To adjust for different population composition and to compare the incidence of malignancy with the general population, standardized incidence rates (SIR) were calculated. To identify risk factors for lymphoma, individual patient data were obtained for multivariate analysis for the year before lymphoma diagnosis.

RESULTS

In 10 years, the cohort composed of 66,953 patient-years yielded 559 malignancies, most frequently lung cancer, followed by gastric cancer, breast cancer, and lymphoma. The overall incidence of malignancies in patients with RA was slightly lower than in the general population (SIR 0.89, 95% CI 0.82-0.97). However, lymphoma risk was significantly higher (SIR 3.43, 95% CI 2.59-4.28), whereas risk of colon, rectal, or liver cancer was lower. Significant risk factors for lymphoma were the use of methotrexate or tacrolimus, and higher age.

CONCLUSION

Patients with RA had no higher overall incidence of malignancies, but lymphoma was significantly more frequent than in the general population.

Multiple Intestinal Ulcers Associated with Primary Epstein-Barr Virus Infection in a Patient with Rheumatoid Arthritis Undergoing Methotrexate Therapy

A 47-year-old woman with a 2-year history of rheumatoid arthritis (RA) undergoing methotrexate treatment developed a perforated ulcer in the ileum for which she underwent emergency surgery. A histological analysis of the extirpated specimen presented a possible Epstein-Barr virus (EBV) infection in the ulcerative lesion without a feature of lymphoproliferative disorder. Interestingly, the patient's serological tests with a paired serum diagnosed a primary EBV infection. The present case emphasizes the importance of being aware of severe enteritis as a possibility for patients with RA, for an accurate diagnosis.

Methotrexate-associated Lymphoproliferative Disease with Multiple Pulmonary Nodules in a Patient with Rheumatoid Arthritis

Patients with rheumatoid arthritis (RA) treated with methotrexate (MTX) sometimes develop lymphoproliferative disease (LPD). MTX-associated LPD can affect nodal or extranodal sites, including the gastrointestinal tract, skin, lungs, kidneys and soft tissues, at almost equal frequency. However, it is very rare for MTX-associated LPD to manifest as multiple nodules in the lungs. We herein report the case of a RA patient who developed MTX-associated LPD with multiple pulmonary nodules during a 5-year course of MTX therapy.

Hepatosplenic Hodgkin lymphoma without lymphadenopathy following reversible methotrexate-associated lymphoproliferative disorder

Lymphoproliferative disorders (LPDs) occur more frequently in rheumatoid arthritis (RA) patients treated with immunosuppressive agents than in the non-RA population. However, the various forms of disease progression have not yet been elucidated in detail. We encountered a case of Epstein-Barr virus (EBV)-positive atypical polymorphous LPD in the cervical and intraabdominal lymph nodes with hepatosplenomegaly in an 88-year-old female with RA who had taken infliximab and methotrexate (MTX) for six years. Although spontaneous remission occurred following the withdrawal of infliximab and MTX, reversible LPD evolved into hepatosplenic Hodgkin lymphoma without lymphadenopathy presenting as a cholestatic febrile illness. Our findings suggest that the recurrent lesions of MTX-associated LPDs may not always coincide with the primary lesion and may present unexplained findings based on various extranodal diseases.

Association of higher methotrexate dose with lymphoproliferative disease onset in rheumatoid arthritis patients

OBJECTIVE

Methotrexate (MTX) is used as an anchor drug for rheumatoid arthritis (RA). Lymphoproliferative disease (LPD) occasionally develops in patients treated with MTX, and is known as MTX-associated LPD (MTX-LPD). Although MTX-LPD occurs mainly in RA patients, it has not been established if MTX administration is an independent risk factor for LPD in RA patients. We examined the clinical characteristics of MTX-LPD in Japanese RA patients and attempted to determine the risk factors for MTX-LPD development.

METHODS

We performed a nested case-control study on RA patients. We enrolled 5,753 RA patients from Kagawa, Japan. In age- and sex-matched patients, we separated patients who did not develop LPD under MTX treatment (MTX non-LPD group) from those that did (MTX-LPD group) and conducted a comparative examination. We used multivariate analysis to determine the independent risk factors for MTX-LPD onset.

RESULTS

There were 28 patients in the MTX-LPD group and 125 patients in the MTX non-LPD group. Multivariate analysis of the parameters extracted by univariate analysis revealed that the mean MTX dose was a risk factor for MTX-LPD after adjusting for age; therefore, higher MTX dose is associated with LPD onset in RA patients.

CONCLUSION

MTX is an independent risk factor for LPD onset in Japanese RA patients.

Optimized nonclinical safety assessment strategies supporting clinical development of therapeutic monoclonal antibodies targeting inflammatory diseases

An increasing number of immunomodulatory monoclonal antibodies (mAbs) and IgG Fc fusion proteins are either approved or in early-to-late stage clinical trials for the treatment of chronic inflammatory conditions, autoimmune diseases and organ transplant rejection. The exquisite specificity of mAbs, in combination with their multi-functional properties, high potency, long half-life (permitting intermittent dosing and prolonged pharamcological effects), and general lack of off-target toxicity makes them ideal therapeutics. Dosing with mAbs for these severe and debilitating but often non life-threatening diseases is usually prolonged, for several months or years, and not only affects adults, including sensitive populations such as woman of child-bearing potential (WoCBP) and the elderly, but also children. Immunosuppression is usually a therapeutic goal of these mAbs and when administered to patients whose treatment program often involves other immunosuppressive therapies, there is an inherent risk for frank immunosuppression and reduced host defence which when prolonged increases the risk of infection and cancer. In addition when mAbs interact with the immune system they can induce other adverse immune-mediated drug reactions such as infusion reactions, cytokine release syndrome, anaphylaxis, immune-complex-mediated pathology and autoimmunity. An overview of the nonclinical safety assessment and risk mitigation strategies utilized to characterize these immunomodulatory mAbs and Fc fusion proteins to support first-in human (FIH) studies and futher clinical development in inflammatory disease indications is provided. Specific emphasis is placed on the design of studies to qualify animal species for toxicology studies, early studies to investigate safety and define PK/PD relationships, FIH-enabling and chronic toxicology studies, immunotoxicity, developmental, reproductive and juvenile toxicity studies and studies to determine the potential for immunosuppression and reduced host defence against infection and cancer. Nonclinical strategies to facilitate clinical and market entry in the most efficient timeframe are presented.

Effects of a biologic agent in a patient with rheumatoid arthritis after treatment for methotrexate-associated B-cell lymphoma: a case report

Background

Several studies have suggested an increased risk of malignant tumor in patients with rheumatoid arthritis. It has been also reported that rheumatoid arthritis patients have a high incidence of lymphoma compared with the general population, and that patients receiving methotrexate, which is the anchor drug for rheumatoid arthritis treatment, can develop lymphoproliferative disease. Nevertheless, management of rheumatoid arthritis after treatment for methotrexate-associated lymphoma has not been fully investigated. We here report a patient with rheumatoid arthritis who developed malignant lymphoma associated with methotrexate therapy. Moreover, we describe the use of a biologic agent for a rheumatoid arthritis patient after treatment for lymphoma associated with methotrexate.

Case presentation

A 60-year-old Japanese man with a 20-year history of rheumatoid arthritis was admitted to our hospital with a left inguinal tumor. Open biopsy was performed and a biopsy specimen revealed diffuse large B-cell lymphoma. As our patient had received methotrexate for 4 years, we diagnosed the lymphoproliferative disease as being methotrexate-related. This lymphoma was not associated with Epstein- Barr virus by Epstein-Barr virus-encoded ribonucleic acid in-situ hybridization, but this patient was an Epstein-Barr virus carrier, regarding serological testing. The lymphoma went into complete remission after 6 courses of rituximab plus cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone/prednisolone therapy. Two years later, however, rheumatoid arthritis activity gradually increased and was not controlled with salazosulfapyridine. Etanercept was administered in view of its possible effect on B-cells, and this reduced the level of disease activity without recurrence of lymphoma.

Conclusion

The management of rheumatoid arthritis after treatment for methotrexate-associated lymphoma has not been fully investigated yet. Etanercept appeared to be safe because of its B-cell effect, but further observation is necessary to make a firm conclusion. Further accumulation of cases is needed to clarify which biologics are safe and effective for treatment of methotrexate-associated B-cell lymphoma.

A clinical, pathological, and genetic characterization of methotrexate-associated lymphoproliferative disorders

OBJECTIVE

Methotrexate-associated lymphoproliferative disorders (MTX-LPD) often regress spontaneously during MTX withdrawal, but the prognostic factors remain unclear. The aim of our study was to clarify the clinical, histological, and genetic factors that predict outcomes in patients with MTX-LPD.

METHODS

Patients with MTX-LPD diagnosed between 2000 and 2012 were analyzed retrospectively regarding their clinical course, site of biopsy, histological typing, Epstein-Barr virus (EBV) in situ hybridization and immunostaining, and HLA type.

RESULTS

Twenty-one patients, including 20 with rheumatoid arthritis (RA) and 1 with polymyositis, were analyzed. The mean dose of MTX was 6.1 mg/week and the mean duration of treatment was 71.1 months. Clinically, 5 patients were diagnosed with EBV-positive mucocutaneous ulcer (EBVMCU) and had polymorphic histological findings. The proportion of those patients successfully treated solely by withdrawal of MTX was significantly greater than that of those without EBVMCU (75% vs 7.7%, p = 0.015). The HLA-B15:11 haplotype was more frequent in patients with EBV+ RA with MTX-LPD than in healthy Japanese controls (p = 0.0079, Bonferroni's method). EBV latency classification and HLA typing were not associated with the prognosis of MTX-LPD in our cohort.

CONCLUSION

Our data demonstrate that patients in the EBVMCU, a specific clinical subgroup of MTX-LPD, had a better clinical outcome when MTX was withdrawn than did other patients with MTX-LPD.

Epstein-Barr virus nuclear antigen 3C interact with p73: Interplay between a viral oncoprotein and cellular tumor suppressor

The p73 protein has structural and functional homology with the tumor suppressor p53, which plays an important role in cell cycle regulation, apoptosis, and DNA repair. The p73 locus encodes both a tumor suppressor (TAp73) and a putative oncogene (ΔNp73). p73 May play a significant role in p53-deficient lymphomas infected with Epstein-Barr virus (EBV). EBV produces an asymptomatic infection in the majority of the global population, but it is associated with several human B-cell malignancies. The EBV-encoded Epstein-Barr virus nuclear antigen 3C (EBNA3C) is thought to disrupt the cell cycle checkpoint by interacting directly with p53 family proteins. Doxorubicin, a commonly used chemotherapeutic agent, induces apoptosis through p53 and p73 signaling such that the lowΔNp73 level promotes the p73-mediated intrinsic pathway of apoptosis. In this report, we investigated the mechanism by which EBV infection counters p73α-induced apoptosis through EBNA3C.

Multi-modality imaging findings of methotrexate-related Epstein-Barr virus-associated hepatic tumor

Methotrexate (MTX)-associated lymphoproliferative disorders (MTX-LPDs) that occur in rheumatoid arthritis patients who were administered MTX for long periods are well known. However, studies on their pathology in forming hepatic tumors are rare. An approach using diagnostic imaging modalities, mainly computed tomography (CT), is considered a very useful tool for the differential diagnosis of various hepatic tumors. In the present study, detailed findings of dynamic CT, magnetic resonance (MR) imaging, and contrast-enhanced ultrasonography of a hepatic tumor that was confirmed as infected by Epstein-Barr virus, in a rheumatoid arthritis patient administered MTX are presented.

Children's Oncology Group's 2013 blueprint for research: Hodgkin lymphoma

In childhood Hodgkin lymphoma, estimated 5 years survival rates exceed 90%. Long-term survival continues to decline from delayed toxicities. Key findings from recent Children's Oncology Group trials include: (1) Radiotherapy selection may be based on early chemotherapy response assessed by both FDG-PET and CT imaging, (2) A new prognostic factor score stratifies patients into risk categories; and (3) novel retrieval regimens were identified. A phase I/II trial is investigating Brentuximab vedotin (Bv) with gemcitabine in relapsed patients. A phase 3 trial will modify conventional chemotherapy and radiotherapy approaches through the addition of Bv, while incorporating translational biology to identify molecular targets.

Co-treatment with arsenic trioxide and ganciclovir reduces tumor volume in a murine xenograft model of nasopharyngeal carcinoma

We have previously shown that disruption of promyelocytic leukemia nuclear bodies (PML NBs) is sufficient to activate the EBV lytic cycle thus making infected cells susceptible to ganciclovir (GCV) mediated killing in vitro. Here we show that co-administration of GCV and arsenic trioxide (ATO), a PML NB disruptor, reduces tumor volume in a xenograft model of nasopharyngeal carcinoma utilizing CNE1 cells. When administered at pharmacologic levels, both GCV and ATO reduced tumor growth while co-treatment with GCV + ATO resulted in a diminution of tumor volume. Treatment with GCV or ATO individually resulted in an increased number of apoptotic cells while co-treatment with GCV + ATO synergistically induced apoptosis. Treatment with ATO or co-treatment with GCV + ATO resulted in expression of EBV lytic proteins. These data suggest that co-treatment with GCV + ATO may provide an effective treatment for nasopharyngeal carcinoma patients.