The role of EBV in post-transplant malignancies: a review

Recent Advances in Adult Post-Transplant Lymphoproliferative Disorder

PTLD is a rare but severe complication of hematopoietic or solid organ transplant recipients, with variable incidence and timing of occurrence depending on different patient-, therapy-, and transplant-related factors. The pathogenesis of PTLD is complex, with most cases of early PLTD having a strong association with Epstein-Barr virus (EBV) infection and the iatrogenic, immunosuppression-related decrease in T-cell immune surveillance. Without appropriate T-cell response, EBV-infected B cells persist and proliferate, resulting in malignant transformation. Classification is based on the histologic subtype and ranges from nondestructive hyperplasias to monoclonal aggressive lymphomas, with the most common subtype being diffuse large B-cell lymphoma-like PTLD. Management focuses on prevention of PTLD development, as well as therapy for active disease. Treatment is largely based on the histologic subtype. However, given lack of clinical trials providing evidence-based data on PLTD therapy-related outcomes, there are no specific management guidelines. In this review, we discuss the pathogenesis, histologic classification, and risk factors of PTLD. We further focus on common preventive and frontline treatment modalities, as well as describe the application of novel therapies for PLTD and elaborate on potential challenges in therapy.

Epstein-Barr Virus Status and Subsequent Thiopurine Exposure Within a Paediatric Inflammatory Bowel Disease Population

The use of thiopurine therapy in Epstein-Barr virus (EBV)-naïve inflammatory bowel disease (IBD) patients remains controversial due to a risk of EBV-associated complications. We evaluated EBV status and outcomes within our paediatric IBD population over an 8-year period; finding that 217 of 409 (53%) screened patients were seropositive for EBV at IBD diagnosis; that thiopurines were used in 189 of 217 (87%) seropositive and 159 of 192 (83%) seronegative patients (P = 0.22); and that 7 of 192 (4%) previously seronegative patients subsequently tested positive for EBV with 6 of 7 (86%) patients having concurrently recorded thiopurine use. All six patients continued thiopurine with/without a period of cessation; no EBV-associated lymphoproliferative disorders/serious complications were recorded within our cohort. A significant proportion of our patients would not receive thiopurine therapy should their use be avoided in EBV-negative patients (47%) or seronegative males (30%). The small but significant risks of thiopurine treatment must be balanced against the potential benefits of successful IBD management; further research into this is required.

Rationally repurposed nitroxoline inhibits preclinical models of Epstein-Barr virus-associated lymphoproliferation

Repurposing of currently used drugs for new indications benefits from known experience with those agents. Rational repurposing can be achieved when newly uncovered molecular activities are leveraged against diseases that utilize those mechanisms. Nitroxoline is an antibiotic with metal-chelating activity used to treat urinary tract infections. This small molecule also inhibits the function of bromodomain and extraterminal (BET) proteins that regulate oncogene expression in cancer. Lymphoproliferation driven by the Epstein-Barr virus (EBV) depends on these same proteins. We therefore tested the efficacy of nitroxoline against cell culture and small animal models of EBV-associated lymphoproliferation. Nitroxoline indeed reduces cell and tumor growth. Nitroxoline also acts faster than the prototype BET inhibitor JQ1. We suggest that this rational repurposing may hold translational promise.

Expansion and Adoptive Transfer of Human Vδ2+ T Cells to Assess Antitumor Effects In Vivo

Recent clinical trials have yielded promising results suggesting that γδ T cell62-based immunotherapies can be effective against hematological malignancies. Human T cells expressing Vγ9Vδ2⁺ receptors are particularly attractive candidates for this application, since they can be readily expanded in vitro in large quantities for adoptive transfer and do not require HLA-matching of donors and recipients. While it is well established that Vγ9Vδ2⁺ T cells are potently cytolytic against many human cancers and it has been shown that they can control transplanted human tumors in xenogeneic model systems, little is known about the parameters that determine the antitumor efficacy of adoptively transferred Vγ9Vδ2⁺ T cells in physiologically relevant scenarios. In particular, it may be important to separate their immunosurveillance functions from those employed in the context of an established tumor. Moreover, it is critical to understand how the presence of an immunosuppressive environment, such as one where tumor-infiltrating T cells are held in check by inhibitory ligands, affects the functions of Vγ9Vδ2⁺ T cells. This chapter describes how to establish Epstein-Barr virus (EBV) infection of human umbilical cord blood mononuclear cells (CBMCs) within immunodeficient mice, so as to drive the in vivo formation of human B cell lymphomas that contain an immunosuppressive environment. Details are provided on how to expand human Vγ9Vδ2⁺ T cells from peripheral blood mononuclear cells (PBMCs), administer them to the mice, and evaluate tumors and other tissues.

Pediatric renal transplantation: A retrospective single-center study on epidemiology and morbidity due to EBV

Pediatric R-Tx patients are at high risk of developing EBV primary infection. Although high DNA replication is a risk factor for PTLD, some patients develop PTLD with low viral load. In this retrospective single-center study including all pediatric patients having received R-Tx (2003-2012 period), we aimed to identify risk factors for uncontrolled reactions to EBV (defined as the presence of a viral load >10 000 copies/mL or PTLD). A Cox proportional hazard model was performed. A total of 117 patients underwent R-Tx at a mean age of 9.7 ± 5.3 years, 46 of them being seronegative for EBV at the time of R-Tx. During follow-up, 54 patients displayed positive EBV viral load, 22 of whom presenting with primary infection. An uncontrolled reaction to EBV was observed in 24 patients, whilst 4 patients developed PTLD. Univariate and multivariate analyses suggested the following risk factors for an uncontrolled reaction: age below 5 years, graft from a deceased donor, ≥5 HLA mismatches, EBV-seronegative status at the time of R-Tx, and a secondary post-Tx loss of anti-EBNA. Monitoring anti-EBNA after R-Tx may contribute to the early identification of patients at risk for uncontrolled reaction.

EBV Persistence--Introducing the Virus

Persistent infection by EBV is explained by the germinal center model (GCM) which provides a satisfying and currently the only explanation for EBVs disparate biology. Since the GCM touches on every aspect of the virus, this chapter will serve as an introduction to the subsequent chapters. EBV is B lymphotropic, and its biology closely follows that of normal mature B lymphocytes. The virus persists quiescently in resting memory B cells for the lifetime of the host in a non-pathogenic state that is also invisible to the immune response. To access this compartment, the virus infects naïve B cells in the lymphoepithelium of the tonsils and activates these cells using the growth transcription program. These cells migrate to the GC where they switch to a more limited transcription program, the default program, which helps rescue them into the memory compartment where the virus persists. For egress, the infected memory cells return to the lymphoepithelium where they occasionally differentiate into plasma cells activating viral replication. The released virus can either infect more naïve B cells or be amplified in the epithelium for shedding. This cycle of infection and the quiescent state in memory B cells allow for lifetime persistence at a very low level that is remarkably stable over time. Mathematically, this is a stable fixed point where the mechanisms regulating persistence drive the state back to equilibrium when perturbed. This is the GCM of EBV persistence. Other possible sites and mechanisms of persistence will also be discussed.

A multifactorial role for P. falciparum malaria in endemic Burkitt's lymphoma pathogenesis

Endemic Burkitt's lymphoma (eBL) arises from the germinal center (GC). It is a common tumor of young children in tropical Africa and its occurrence is closely linked geographically with the incidence of P. falciparum malaria. This association was noted more than 50 years ago. Since then we have learned that eBL contains the oncogenic herpes virus Epstein-Barr virus (EBV) and a defining translocation that activates the c-myc oncogene. However the link to malaria has never been explained. Here we provide evidence for a mechanism arising in the GC to explain this association. Accumulated evidence suggests that eBL arises in the GC when deregulated expression of AID (Activation-induced cytidine deaminase) causes a c-myc translocation in a cell latently infected with Epstein-Barr virus (EBV). Here we show that P. falciparum targets GC B cells via multiple pathways to increase the risk of eBL. 1. It causes deregulated expression of AID, thereby increasing the risk of a c-myc translocation. 2. It increases the number of B cells transiting the GC. 3. It dramatically increases the frequency of these cells that are infected with EBV and therefore protected from c-myc induced apoptosis. We propose that these activities combine synergistically to dramatically increase the incidence of eBL in individuals infected with malaria.

Endemic Burkitt's lymphoma (eBL) is a common tumor of young children in tropical Africa that is closely linked geographically with P. falciparum malaria. This association was noted more than 50 years ago. Since then we have learned that eBL contains the oncogenic herpes virus Epstein-Barr virus and a defining translocation that activates the c-myc oncogene. However the link to malaria has never been explained. Here we show that malaria has multiple effects that all focus on germinal center (GC) B cells that are known to be the origin of eBL. Together these effects of malaria act synergistically to dramatically increase the risk of developing eBL in individuals infected with the parasite. Clinical interventions that lessen the impact of malaria on GC B cells should dramatically decrease the incidence eBL.

Adapted treatment of Epstein-Barr virus infection to prevent posttransplant lymphoproliferative disorder after heart transplantation

Up to 35% of posttransplant lymphoproliferative disorder (PTLD) cases occur within 1 year of transplantation, and over 50% are associated with Epstein-Barr virus (EBV). EBV primary infection and reactivation are PTLD predictive factors, but there is no consensus for their treatment. We conducted a prospective single-center study on 299 consecutive heart-transplant patients treated with the same immunosuppressive regimen and monitored by repetitive EBV viral-load measurements and endomyocardial biopsies to detect graft rejection. Immunosuppression was tapered on EBV reactivation with EBV viral loads >10(5) copies/mL or primary infection. In the absence of response at 1 month or a viral load >10(6) copies/mL, patients received one rituximab infusion (375 mg/m(2) ). All patients responded to treatment without increased graft rejection. One primary infection case developed a possible PTLD, which completely responded to diminution of immunosuppression, and one patient, whose EBV load was unevaluable, died of respiratory complications secondary to PTLD. Compared with a historical cohort of 820 patients, PTLD incidence was decreased (p = 0.033) by a per-protocol analysis. This is the largest study on EBV primary infection/reactivation treatment, the first using rituximab following solid organ transplantation to prevent PTLD and the first to demonstrate an acceptable tolerability profile in this setting.

Molecular pathogenesis of B-cell posttransplant lymphoproliferative disorder: what do we know so far?

Posttransplant lymphoproliferative disorder (PTLD) is a potentially fatal disease that arises in 2%-10% of solid organ and hematopoietic stem cell transplants and is most frequently of B-cell origin. This very heterogeneous disorder ranges from benign lymphoproliferations to malignant lymphomas, and despite the clear association with Epstein-Barr Virus (EBV) infection, its etiology is still obscure. Although a number of risk factors have been identified (EBV serostatus, graft type, and immunosuppressive regimen), it is currently not possible to predict which transplant patient will eventually develop PTLD. Genetic studies have linked translocations (involving C-MYC, IGH, BCL-2), various copy number variations, DNA mutations (PIM1, PAX5, C-MYC, RhoH/TTF), and polymorphisms in both the host (IFN-gamma, IL-10, TGF-beta, HLA) and the EBV genome to B-cell PTLD development. Furthermore, the tumor microenvironment seems to play an important role in the course of disease representing a local niche that can allow antitumor immune responses even in an immunocompromised host. Taken together, B-cell PTLD pathogenesis is very complex due to the interplay of many different (patient-dependent) factors and requires thorough molecular analysis for the development of novel tailored therapies. This review aims at giving a global overview of the currently known parameters that contribute to the development of B-cell PTLD.

Advances in Virus-Directed Therapeutics against Epstein-Barr Virus-Associated Malignancies

Epstein-Barr virus (EBV) is the causal agent in the etiology of Burkitt's lymphoma and nasopharyngeal carcinoma and is also associated with multiple human malignancies, including Hodgkin's and non-Hodgkin's lymphoma, and posttransplantation lymphoproliferative disease, as well as sporadic cancers of other tissues. A causal relationship of EBV to these latter malignancies remains controversial, although the episomic EBV genome in most of these cancers is clonal, suggesting infection very early in the development of the tumor and a possible role for EBV in the genesis of these diseases. Furthermore, the prognosis of these tumors is invariably poor when EBV is present, compared to their EBV-negative counterparts. The physical presence of EBV in these tumors represents a potential "tumor-specific" target for therapeutic approaches. While treatment options for other types of herpesvirus infections have evolved and improved over the last two decades, however, therapies directed at EBV have lagged. A major constraint to pharmacological intervention is the shift from lytic infection to a latent pattern of gene expression, which persists in those tumors associated with the virus. In this paper we provide a brief account of new virus-targeted therapeutic approaches against EBV-associated malignancies.

Histone deacetylase inhibitors are potent inducers of gene expression in latent EBV and sensitize lymphoma cells to nucleoside antiviral agents

Induction of EBV lytic-phase gene expression, combined with exposure to an antiherpes viral drug, represents a promising targeted therapeutic approach to EBV-associated lymphomas. Short-chain fatty acids or certain chemotherapeutics have been used to induce EBV lytic-phase gene expression in cultured cells and mouse models, but these studies generally have not translated into clinical application. The recent success of a clinical trial with the pan-histone deacetylase (pan-HDAC) inhibitor arginine butyrate and the antiherpes viral drug ganciclovir in the treatment of EBV lymphomas prompted us to investigate the potential of several HDAC inhibitors, including some new, highly potent compounds, to sensitize EBV(+) human lymphoma cells to antiviral agents in vitro. Our study included short-chain fatty acids (sodium butyrate and valproic acid); hydroxamic acids (oxamflatin, Scriptaid, suberoyl anilide hydroxamic acid, panobinostat [LBH589], and belinostat [PXD101]); the benzamide MS275; the cyclic tetrapeptide apicidin; and the recently discovered HDAC inhibitor largazole. With the exception of suberoyl anilide hydroxamic acid and PXD101, all of the other HDAC inhibitors effectively sensitized EBV(+) lymphoma cells to ganciclovir. LBH589, MS275, and largazole were effective at nanomolar concentrations and were 10(4) to 10(5) times more potent than butyrate. The effectiveness and potency of these HDAC inhibitors make them potentially applicable as sensitizers to antivirals for the treatment of EBV-associated lymphomas.

Synchronous hepatic, mesenteric and pulmonary Epstein-Barr virus-associated smooth muscle tumors in a renal transplant recipient

Epstein-Barr virus-associated smooth muscle tumors (EBV-SMT) are distinct lesions that occur in immunocompromised patients. EBV-SMT following solid organ transplantation are rare and generally have an indolent biological behavior. Post-transplant EBV-SMT have been reported in various anatomical locations. This report describes a synchronous and multicentric development of EBV-SMT in liver, mesentery, and lung of a 33-yr-old male patient, 10 yr after a deceased allograft renal transplantation. The hepatic and mesenteric tumors were available for study. These tumors were composed of bland looking, desmin-positive, spindle-shaped cells which showed a strong nuclear staining for EBV with in situ hybridization technique. A literature review of post solid organ transplant EBV-SMT in the liver and lung, particularly regarding their pathogenesis, synchronicity and biological behavior would be provided.

Endemic Burkitt's lymphoma as a polymicrobial disease: new insights on the interaction between Plasmodium falciparum and Epstein-Barr virus

Despite the well-established relationship between endemic Plasmodium falciparum malaria and Epstein-Barr virus (EBV) infection in the genesis of endemic Burkitt's lymphoma (eBL), very little research has examined the interaction between these two pathogens. eBL, the most prevalent childhood cancer in equatorial Africa where malaria is holoendemic, is a high-grade B cell lymphoma characterized by a c-myc translocation and the consistent presence of EBV. After primary infection, EBV establishes a life-long persistent infection characterized by virus shedding into saliva. African children are infected early in life and most have sero-converted by 3 years of age while sero-conversion tends to occur later in developed countries. Acute and chronic malaria infections profoundly affect the B cell compartment, inducing polyclonal activation, hyper-gammaglobulinemia and a dramatic increase in the levels of circulating EBV. In this review we present and discuss recent data suggesting a molecular link between the parasite, the B cell and EBV and provide evidence that adds to the concept of polymicrobial disease pathogenesis in eBL. Following the observation of EBV reactivation in children living in malaria endemic areas and its relationship with acute malaria infection, we identified the cystein-rich inter-domain region 1 alpha (CIDR1 alpha) of the Plasmodium falciparum membrane protein 1 as a polyclonal B cell activator. CIDR1 alpha increases B cell survival and preferentially activates the memory compartment where EBV is known to persist. Analysis of the mechanisms of interaction between CIDR1 alpha and EBV in the context of B cells demonstrated that CIDR1 alpha induces virus production in the EBV-infected B cell line Akata and in latently infected primary B cells derived from the peripheral blood of healthy carriers and children with eBL. This is the first demonstration that EBV can be reactivated directly by another pathogen. Our results suggest that P. falciparum antigens such as PfEMP1 can directly induce EBV reactivation during malaria infections. The increased viral load and the concomitant polyclonal B cell activation with enhanced B cell survival may augment the risk of eBL development in children living in malaria-endemic areas.

Epstein – Barr viral load, interleukin-6 and interleukin-10 levels in post-transplant lymphoproliferative disease: A nested case – control study in a renal transplant cohort

The possible correlation among Epstein-Barr virus (EBV) load, interleukin-6 (IL-6) and interleukin-10 (IL-10) levels has become an attractive issue and can provide a useful tool for diagnosis and monitoring of patients at risk for post-transplant lymphoproliferative disease (PTLD) development. At the time of diagnosis of PTLD, 11 patients were prospectively enrolled and 55 nested controls were selected from a 1800 renal transplant cohort. Real-time polymerase chain reaction (PCR) was used to quantify EBV load in peripheral blood mononuclear cells (PBMC). Serum IL-6 and IL-10 levels were determined using an enzyme-linked immunosorbent assay (ELISA). The median EBV load of PTLD cases was 17400 copies/10(6) PBMC, statistically different from controls (P=0.001). The median IL-6 level of PTLD cases was not different from controls (P=0.079). However, median IL-10 levels showed a significant difference in both groups (P < or = 0.001). The receiver-operating characteristic (ROC) curve analysis was applied to estimate the IL-10 cut-off value predictive of PTLD development. We found that 73.5 pg/ml has high sensitivity (1.00) and specificity (0.85). Also, Pearson's analysis showed a strong correlation between EBV load and serum IL-10 concentration (P < or = 0.001). This nested case-control study demonstrates that EBV load at diagnosis of PTLD correlates with IL-10 levels, and that monitoring of IL-10 can provide a less expensive and less time-consuming tool for PTLD diagnosis and close follow-up of patients at risk. Furthermore, we were able to define a cut-off value of IL-10 mostly predictive of PTLD development in this cohort. Our data suggest that serial measurements prior to PTLD development must be carried out to validate our hypothesis.

The curious case of the tumour virus: 50 years of Burkitt's lymphoma

Burkitt's lymphoma (BL) was first described 50 years ago, and the first human tumour virus Epstein-Barr virus (EBV) was discovered in BL tumours soon after. Since then, the role of EBV in the development of BL has become more and more enigmatic. Only recently have we finally begun to understand, at the cellular and molecular levels, the complex and interesting interaction of EBV with B cells that creates a predisposition for the development of BL. Here, we discuss the intertwined histories of EBV and BL and their relationship to the cofactors in BL pathogenesis: malaria and the MYC translocation.

Primary CD56+ NK/T-cell lymphoma of the rectum accompanied with refractory ulcerative colitis

A case of primary NK/T-cell lymphoma of the rectum accompanied with ulcerative colitis (UC) in a 73-year-old man is reported. He had a 6-year history of repeated admission to our hospital for UC. Total colonoscopy performed 4 months after resolution of refractory UC complicated by cytomegalovirus colitis showed a markedly submucosal tumor in the rectum, which was histologically diagnosed as malignant lymphoma. The findings of computed tomography of the chest and abdomen, gallium scintigraphy, abdominal ultrasonography, and upper gastrointestinal endoscopy showed no abnormal lesions. Therefore, based on a diagnosis of localized rectal lymphoma with UC, proctocolectomy was performed. The resected specimen showed three submucosal tumors in the rectum with local nodal involvement. Histologically, the tumors were characterized by diffusely infiltrating sheets of large atypical lymphoid cells, which were negative for CD4, CD8, and CD20 but were positive for CD56, CD3, and granzyme B. The presence of Epstein-Barr virus (EBV) infection in neoplastic cells was shown by in situ hybridization for EBV-encoded early small RNA1 (EBER-1). Based on these findings, the patient was diagnosed with primary CD56+ NK/T-cell lymphoma of the rectum (stage IIE). This is the first case report of primary rectal NK/T-cell lymphoma accompanied with UC.

CD34+ cord blood cell-transplanted Rag2-/- gamma(c)-/- mice as a model for Epstein-Barr virus infection

Recent studies suggest that Epstein-Barr virus (EBV) can infect naïve B cells, driving them to differentiate into resting memory B cells via the germinal center reaction. This hypothesis has been inferred from parallels with the biology of normal B cells but has never been proven experimentally. Rag2(-/-) gamma(c)(-/-) mice that were transplanted with human CD34(+) cord blood cells as newborns were recently shown to develop human B, T, and dendritic cells, constituting lymphoid organs in situ. Here we used this model to better define the strategy of EBV infection of human B cells in vivo and to compare this model system with different conditions of EBV infection in humans. Our results support the model of EBV persistence in vivo in cases that were characterized by follicular hyperplasia and a relatively normal CD4(+) and CD8(+) T-cell distribution. Intriguingly, in cases that were characterized by nodular and diffuse proliferation with a preponderance of CD8(+) T cells, similar to infectious mononucleosis, EBV still infects naïve B cells but also induces clonal expansion and ongoing somatic mutations without germinal center reactions. Our results reveal different strategies of EBV infection in B cells that possibly result from variations in the host immune response. Future experiments might allow understanding of the mechanisms responsible for persistent EBV infection and provide targets for more highly tailored therapeutic interventions.

Detection of Epstein-Barr virus in children and adolescents with Burkitt's lymphoma by in situ hybridization using tissue microarrays

In this retrospective study, we evaluated 53 patients diagnosed with Burkitt's lymphoma (BL). Patients were admitted to the Pediatric Department of Santa Casa de São Paulo, Brazil from August 1988 to September 2006. The male gender was found more frequently in the proportion of three males to one female. At the time of the diagnosis, the mean age was 6 years. The most frequent clinical presentation was abdominal (extra nodal) in 42 (79.2%) cases. The patients were treated with chemotherapy using two different treatment methods, 30 cases until September 1994 with BGLTI -87 and the other 23 until September of 2006 with BGLTI -96. According to Murphy's classification, 90.2% of the patients were diagnosed as stages III and VI showing an advanced disease at time of diagnosis. Using Tissue Microarrays (TMA); we searched for the expression of the Epstein-Barr virus (EBV) RNA in 50 patients. The presence of EBV using in situ hybridization was found in 33/50 (66%) and there was no association between the presence of the virus in the tumor cells or patient age, as well as the survival rate. There was 74.5% global survival rate until September, 2005 of 12 years and 8 months. The disease free survival rate was 86.5%. The frequency of the EBV association with this neoplasia in Brazil is intermediate between the endemic and sporadic forms of disease.

Monitoring of Epstein-Barr virus load after hematopoietic stem cell transplantation for early intervention in post-transplant lymphoproliferative disease

Epstein-Barr virus (EBV)-associated post-transplant lymphoproliferative disease is a life-threatening complication following hematopoietic stem cell transplantation. A quantitative polymerase chain reaction to evaluate EBV-genome copy numbers based on a nested polymerase chain reaction and an end-point dilution was used. Applying this assay EBV load was prospectively screened weekly in 123 patients after transplantation. The results demonstrate that EBV reactivations with more than 1,000 EBV-genome copies measured in 10(5) peripheral blood mononuclear cells were observed in 31 patients (25.2%). Three patients developed lymphoproliferative disease with extremely high EBV-genome copies in peripheral blood mononuclear cells (>100,000 copies/10(5) cells) and plasma. After combined antiviral and immune therapy two of three patients showed a dramatic decrease of EBV load and survived, while the third patient died of lymphoma. A subclinical EBV reactivation was observed in 24 cases (19.5%) with EBV-genome copies in 10(5) peripheral blood mononuclear cells ranging between 2,500 and mostly 10,000. After reduction of immunosuppression the EBV levels normalized. In four patients, the high copy number of > or =80,000 copies/10(5) peripheral blood mononuclear cells and plasma positivity prompted us to start pre-emptive therapy with rituximab and cidofovir for prevention of lymphoproliferative disease. After drug administration the high EBV load was reduced remarkably. Ninety-two patients (74.8%) who had < or =1,000 copies/10(5) peripheral blood mononuclear cells did not develop EBV-associated lymphoproliferative disease. In conclusion, monitoring of EBV load is a sensitive and useful parameter in the surveillance of EBV reactivation for early intervention in EBV-associated lymphoproliferative disease as well as for follow-up of the efficacy of therapy.

Risk factors for development of a second lymphoid malignancy in patients with chronic lymphocytic leukaemia

Previous studies suggested that patients with chronic lymphocytic leukaemia (CLL) are at a three- to fivefold increased risk of developing a second lymphoproliferative disorder (LPD). This observational cohort study used the Mayo Clinic CLL Database to identify factors associated with developing a second LPD. A second LPD was identified in 26 (2.7%) of 962 CLL patients during a median follow-up of 3.3 years. Diffuse large B-cell lymphoma was the most common subtype of secondary LPD (12 of 26 cases). Patients previously treated for CLL had a trend toward higher prevalence of second LPD (4%) compared with previously untreated patients (2%; P = 0.053). More strikingly, patients treated with purine nucleoside analogues (PNA) had a significantly increased risk of subsequent second LPD (5.2%) compared with patients who had not received PNA (1.9%; P = 0.008). No statistically significant association was observed between risk of second LPD and other CLL characteristics (ZAP-70, CD38, IgV(H) mutation status or cytogenetic abnormalities). In this series, prior treatments with PNA or anthracyclines were the only significant factors associated with risk of developing a second LPD in patients with CLL. Physicians should strictly adhere to established criteria to initiate treatment for CLL patients who are not participating in clinical trials.

Expression of CCL17 and CCL22 by latent membrane protein 1-positive tumor cells in age-related Epstein-Barr virus-associated B-cell lymphoproliferative disorder

Age-related Epstein-Barr virus-positive (EBV(+)) B-cell lymphoproliferative disorder (ALPD) is a disease entity identified from a large-scale re-survey of cases diagnosed as diffuse large B-cell lymphoma. ALPD is a group of EBV(+) polymorphic B-cell lymphoma typically seen in elderly patients. An age-associated decline in host immunity against EBV might be partly responsible for the pathogenesis of ALPD. Histologically, ALPD is often characterized by a minor proportion of EBV-encoded RNA-positive tumor cells in a background of extensive cellular infiltration, similar to that of classical Hodgkin's lymphoma. In contrast to Hodgkin and Reed-Sternberg cells, ALPD tumor cells are clearly positive for B cell markers CD20 and/or CD79a. Hodgkin and Reed-Sternberg cells produce various chemokines, including CCL17 and CCL22, that attract chemokine receptor CCR4-expressing Th2 cells and regulatory T cells. Previously, we have shown that EBV-immortalized B cells also produce CCL17 and CCL22 through latent membrane protein 1 (LMP1)-mediated activation of nuclear factor kappaB. Here we examined expression of CCL17 and CCL22 in ALPD. ALPD tumor cells were often heterogeneous in size in accordance with the differential expression of EBV latent genes at the single cell level. LMP1-expressing tumor cells were typically large in size and selectively positive for CCL17 and CCL22. CCR4(+) cells and forkhead box protein 3(+) regulatory T cells were abundantly present, and the majority of forkhead box protein 3(+) cells were CCR4(+). Collectively, our data show production of CCL17 and CCL22 by LMP1(+) large-sized tumor cells and accumulation of CCR4-expressing cells including regulatory T cells in ALPD.

Repertoire and frequency of immune cells reactive to Epstein-Barr virus-derived autologous lymphoblastoid cell lines

Answers to questions about frequency and repertoire of immune cells, relative contributions made by different types of immune cells toward the total Epstein-Barr virus (EBV)-directed response and the variation of such responses in healthy persons have been elusive because of disparities in assays, antigen presenting cells, and antigenic sources used in previous experiments. In this study, we addressed these questions using an assay that allowed direct comparison of responses generated by different types of cells of the immune system. This short-term (20-hour) ex vivo assay measured interferon-gamma production by blood cells in response to autologous EBV-transformed lymphoblastoid cell lines (LCLs). Our experiments defined the variation in responses among persons and clearly distinguished 10 healthy EBV-immune from 10 healthy EBV-naive persons. In EBV-immune persons, 33% of responding cells were CD4(+), 43.3% were CD8(+), and 12.9% were gamma-delta T cells. LCL-reactive CD8(+) T cells were only 1.7-fold more frequent than similarly reactive CD4(+)T cells. Responses by gamma-delta T cells were 6-fold higher in seropositive than in seronegative persons. Our findings emphasize the importance of CD4(+) and gamma-delta T-cell responses and have implications for immunotherapy and for identifying defects in T-cell populations that might predispose to development of EBV-associated lymphomas.

Effect of cytomegalovirus prophylaxis with immunoglobulin or with antiviral drugs on post-transplant non-Hodgkin lymphoma: a multicentre retrospective analysis

BACKGROUND

Post-transplant non-Hodgkin lymphoma is a feared complication of immunosuppressive treatment and is associated with high mortality. Most post-transplant lymphomas develop from the uncontrolled proliferation of Epstein-Barr-virus (EBV)-infected B lymphocytes. No reliable methods for the prevention of EBV infection and lymphoma are available. We aimed to elucidate the effect of prophylactic treatment for cytomegalovirus (CMV) infection on the incidence of post-transplant lymphomas.

METHODS

In a multicentre retrospective study, we analysed the incidence of post-transplant non-Hodgkin lymphoma in 44 828 recipients of deceased-donor kidney transplants who were reported to the scientific registry of the Collaborative Transplant Study. Patients had received antiviral drugs (aciclovir or ganciclovir) or anti-CMV immunoglobulin to prevent CMV infection according to the transplant centres' protocols, or no CMV prophylaxis. Standardised incidence ratios (SIR) of lymphoma were calculated and compared by chi(2) analyses

FINDINGS

During the first post-transplantation year, 30 255 patients who did not receive CMV prophylaxis developed lymphomas at SIR 26.4. Lymphoma incidence in 12 470 patients who received antiviral treatment was nearly identical (SIR 24.2, p=0.62) to that in patients who did not receive CMV prophylaxis. However, 2103 patients who received anti-CMV immunoglobulin showed a complete absence of lymphomas in the first after-transplantation year (SIR 0; p=0.012 vs no treatment, p=0.016 vs antivirals). In the subsequent 5 years of follow-up, new cases of lymphoma developed at similar rates in all three groups (p=0.97).

INTERPRETATION

These findings suggest that prophylactic anti-CMV immunoglobulin prevents the development of early post-transplant non-Hodgkin lymphoma in kidney-graft recipients. Prophylactic treatment with antiviral drugs does not reduce the risk of post-transplant lymphoma.

Short, discontinuous exposure to butyrate effectively sensitizes latently EBV-infected lymphoma cells to nucleoside analogue antiviral agents

Antiviral drugs alone have been unsuccessful in the treatment of Epstein-Barr virus (EBV)-associated malignancies because the virus maintains a latent state of replication in these tumors. In recent years, novel therapeutic approaches are being investigated wherein lytic replication of the virus is induced prior to the use of cytotoxic antiviral drugs. The choice of suitable agents to induce lytic replication has been a critical step in this novel approach. We have previously demonstrated that butyrate derivatives induce a lytic pattern of EBV gene expression in patient-derived EBV-positive lymphoblastoid cell lines and, together with nucleoside analogue ganciclovir, effectively reduce or eliminate tumor growth in humans. Butyrate has drawbacks as a therapeutic agent, however, as constant intravenous infusion is required to achieve detectable plasma levels of this drug. In this study, we investigated whether discontinuous exposure to butyrate is capable of initiating lytic phase gene expression and thymidine kinase induction, and sensitizing EBV-positive lymphoma cells to ganciclovir-mediated cell growth arrest and apoptosis. We demonstrate that multiple daily 6-h exposures of the EBV-positive Burkitt's lymphoma cell line P3HR1 to butyrate induced sustained expression of the EBV lytic phase protein BMRF. Viral thymidine kinase was also induced by intermittent exposure, although to a lower level than with continuous exposure treatment. However, discontinuous exposure to butyrate in combination with ganciclovir induced a similar level of tumor cell growth inhibition as did continuous treatment, as measured by serial enumeration of viable cells, MTT cell proliferation assays and measurement of cellular DNA content. We further demonstrated that those cells which survived initial exposure to butyrate plus ganciclovir remained susceptible to further cycles of combination treatment. These findings suggests that continuous infusion of butyrate may not be necessary for maintaining viral thymidine kinase gene expression and sensitization to antiviral agents in EBV-associated tumors, and that therapeutic regimens which employ more convenient, discontinuous exposure to butyrate may also be effective clinically.

Short, discontinuous exposure to butyrate effectively sensitizes latently EBV-infected lymphoma cells to nucleoside analogue antiviral agents

Antiviral drugs alone have been unsuccessful in the treatment of Epstein-Barr virus (EBV)-associated malignancies because the virus maintains a latent state of replication in these tumors. In recent years, novel therapeutic approaches are being investigated wherein lytic replication of the virus is induced prior to the use of cytotoxic antiviral drugs. The choice of suitable agents to induce lytic replication has been a critical step in this novel approach. We have previously demonstrated that butyrate derivatives induce a lytic pattern of EBV gene expression in patient-derived EBV-positive lymphoblastoid cell lines and, together with nucleoside analogue ganciclovir, effectively reduce or eliminate tumor growth in humans. Butyrate has drawbacks as a therapeutic agent, however, as constant intravenous infusion is required to achieve detectable plasma levels of this drug. In this study, we investigated whether discontinuous exposure to butyrate is capable of initiating lytic phase gene expression and thymidine kinase induction, and sensitizing EBV-positive lymphoma cells to ganciclovir-mediated cell growth arrest and apoptosis. We demonstrate that multiple daily 6-h exposures of the EBV-positive Burkitt's lymphoma cell line P3HR1 to butyrate induced sustained expression of the EBV lytic phase protein BMRF. Viral thymidine kinase was also induced by intermittent exposure, although to a lower level than with continuous exposure treatment. However, discontinuous exposure to butyrate in combination with ganciclovir induced a similar level of tumor cell growth inhibition as did continuous treatment, as measured by serial enumeration of viable cells, MTT cell proliferation assays and measurement of cellular DNA content. We further demonstrated that those cells which survived initial exposure to butyrate plus ganciclovir remained susceptible to further cycles of combination treatment. These findings suggests that continuous infusion of butyrate may not be necessary for maintaining viral thymidine kinase gene expression and sensitization to antiviral agents in EBV-associated tumors, and that therapeutic regimens which employ more convenient, discontinuous exposure to butyrate may also be effective clinically.

EBV and systemic lupus erythematosus: a new perspective

We have proposed that EBV uses mature B cell biology to access memory B cells as a site of persistent infection. A central feature of this model is that EBV adapts its gene expression profile to the state of the B cell it resides in and that the level of infection is stable over time. This led us to question whether changes in the behavior or regulation of mature B cells would alter the state of EBV persistence. To investigate this, we studied the impact of systemic lupus erythematosus (SLE), a disease characterized by immune dysfunction, on EBV infection. We show that patients with SLE have abnormally high frequencies of EBV-infected cells in their blood, and this is associated with the occurrence of SLE disease flares. Although patients with SLE have frequencies of infected cells comparable to those seen in immunosuppressed patients, in SLE the effect was independent of immunosuppressive therapy. Aberrant expression of viral lytic (BZLF1) and latency (latency membrane proteins 1 and 2a) genes was also detected in the blood of SLE patients. We conclude that the abnormal regulation of EBV infection in SLE patients reflects the sensitivity of the virus to perturbation of the immune system.

Hematologic aspects of myeloablative therapy and bone marrow transplantation

The transplantation of bone marrow cells or isolated hematopoietic stem cells from the bone marrow or peripheral blood is a widely utilized form of therapy for patients with incurable diseases of the hematopoietic and immune systems. Successful engraftment of the transplanted stem cells in an adequately prepared recipient normally leads to bone marrow reconstitution over a period of several weeks, accompanied by more gradual reconstitution of the immune system. Since the recipient is profoundly ill during the initial treatment period, laboratory data is critical for monitoring engraftment, detecting residual/recurrent disease, and identifying problems that may delay bone marrow reconstitution or lead to other medical complications. Accurate blood cell counts are imperative, and most bone marrow transplantation patients undergo periodic monitoring with bone marrow aspirates and biopsies with cytogenetic, molecular, and multiparametric flow cytometric studies. The potential complications of bone marrow transplantation include engraftment failure and delayed engraftment, infection, residual bone marrow disease, acute and chronic graft versus host disease, myelofibrosis, therapy-related acute leukemia, post-transplant lympho-proliferative disorders, and toxic myelopathy.

Expression of the interferon-inducible chemokine IP-10 (CXCL10), a chemokine with proposed anti-neoplastic functions, in Hodgkin lymphoma and nasopharyngeal carcinoma

Hodgkin lymphoma (HL) and nasopharyngeal carcinoma (NPC) are characterized by their association with Epstein-Barr virus (EBV) and an abundant infiltrate of reactive lymphoid cells. The presence of this lymphoid stroma may influence the effect of anti-viral immunotherapy. The interferon-inducible chemokine IP-10 has anti-neoplastic effects in several model systems mediated by T-cells expressing the CXCR3 chemokine receptor. Using in situ hybridization, it is shown that IP-10 is expressed in neoplastic cells of HL and correlates both with the mixed cellularity histotype and with EBV infection. IP-10 expression was also detected in tumour cells of most NPCs as well as in EBV-negative squamous cell carcinomas of the tongue. Thus, in carcinomas, IP-10 expression showed no correlation with EBV infection. Numerous CXCR3-positive lymphocytes were detected in the lymphoid stroma of HL and NPC, raising the possibility of a Th1-predominant immune response in these cases. In view of the proposed anti-neoplastic functions of IP-10 and CXCR3-positive lymphocytes, these findings are unexpected and raise the possibility that endogenous IP-10 expression in the context of human tumours may not exert the anti-tumour effects ascribed to it by in vitro experiments.

Richter's transformation of chronic lymphocytic leukemia

Transformation of CLL into a large cell lymphoma has an incidence of 3-5%. We have studied 101 cases of CLL treated with fludarabine over a 10-year period (1990-2000) and observed a 12% incidence of transformation. In six of 12 patients, transformation was documented within 4 months following treatment with fludarabine. Pathological material, available in nine cases, was investigated for latent EBV by staining for LMP-1 by immunohistochemistry and EBERs-1 and 2 by in situ hybridisation. LMP-1 and EBERs were demonstrated in three of the nine samples. In two cases there was a different pattern of immunoglobulin gene rearrangement in the transformed cells assessed by PCR (FR3 fragment) compared to the original CLL clone. One of these two cases showed evidence of latent EBV. The other seven cases, of which two were EBV positive, showed identical pattern of Ig gene rearrangement in both the CLL and the transformed cells. We suggest that the relatively high incidence of transformation in this series may be due to immunosuppression mainly related to fludarabine, although other agents and prior therapies may have also contributed.

Aggressive B-cell lymphomas: a review based on the workshop of the XI Meeting of the European Association for Haematopathology

The generic term aggressive B-cell lymphoma includes a variety of entities, each with particular diagnostic and therapeutic issues. To define these entities better and to help confront such issues, a workshop was organized by the European Association of Haematopathology (EAHP) and the Society of Haematology during the XI Meeting of the EAHP, held in Italy in May 2002. Participants were asked to submit cases under various categories and all cases submitted were examined and reviewed by the panel members. The panel's diagnoses formed the basis for discussion at the workshop and a limited number of cases were selected to be presented in more detail and discussed during the workshop. After the workshop the panel met again to discuss the outcome, summarized in this report, which describes the panel's proposals regarding diagnostic criteria, terminology, the definition of new entities and evaluation of biological differential and new prognostic parameters.

Viruses and tumours--an update

In the 40 years since the publication of the article by Harris (Eur J Cancer 1965, 1, 183-188), considerable progress has been made towards the understanding of the contribution of infectious agents to the development of tumours. It is estimated that 15-20% of human malignancies may have an infectious aetiology. This article attempts to summarise the current level of our knowledge with respect to tumour-associated viruses, and to place this in the context of the earlier article by Harris (Eur J Cancer 1965, 1, 183-188).

Epstein–Barr virus-specific cytotoxic T-lymphocytes for adoptive immunotherapy of post-transplant lymphoproliferative disease

Post-transplant lymphoproliferative disease (PTLD) refers to a collection of clinically and pathologically diverse tumours associated with iatrogenic immunosuppression following transplantation. In most cases, tumourigenesis results from a deficit in Epstein-Barr virus (EBV)-specific cytotoxic T-lymphocyte (CTL) activity that leads to uncontrolled EBV-driven outgrowth of latently infected B-lymphocytes. Conventional treatment for PTLD typically involves a reduction in immunosuppression, but this approach is frequently unsuccessful and mortality remains high. An alternative, adoptive immunotherapy, involving the administration of EBV-specific CTLs cultured in vitro has been developed with the aim of selectively reconstituting EBV-directed immunity and effecting targeted tumour destruction. This approach has been the subject of several clinical studies, and these provide encouraging evidence of its clinical efficacy. This review presents an overview of the pathogenesis of PTLD and examines current progress in the use of adoptive immunotherapy for its treatment.

Acute infection with Epstein-Barr virus targets and overwhelms the peripheral memory B-cell compartment with resting, latently infected cells

In this paper we demonstrate that during acute infection with Epstein-Barr virus (EBV), the peripheral blood fills up with latently infected, resting memory B cells to the point where up to 50% of all the memory cells may carry EBV. Despite this massive invasion of the memory compartment, the virus remains tightly restricted to memory cells, such that, in one donor, fewer than 1 in 10(4) infected cells were found in the naive compartment. We conclude that, even during acute infection, EBV persistence is tightly regulated. This result confirms the prediction that during the early phase of infection, before cellular immunity is effective, there is nothing to prevent amplification of the viral cycle of infection, differentiation, and reactivation, causing the peripheral memory compartment to fill up with latently infected cells. Subsequently, there is a rapid decline in infected cells for the first few weeks that approximates the decay in the cytotoxic-T-cell responses to viral replicative antigens. This phase is followed by a slower decline that, even by 1 year, had not reached a steady state. Therefore, EBV may approach but never reach a stable equilibrium.

Lymphoproliferative disease after allogeneic stem cell transplantation--pre-emptive diagnosis by quantification of Epstein-Barr virus DNA in serum

BACKGROUND

Lymphoproliferative disease (PTLD) is a life-threatening complication of organ transplantation. In matched, allogeneic, non-T-cell-depleted stem-cell transplantations (SCT) the disease develops early but has been thought to be rare.

OBJECTIVES

We determined by strict histopathological criteria the incidence of fatal Epstein-Barr-virus (EBV)-related PTLD in a large number of SCT, and assessed the diagnostic value of a real-time quantitative polymerase chain reaction (qPCR) for EBV-DNA in serum specimens.

STUDY DESIGN

Of the 257 SCT performed in Helsinki during 1994-1999, 132 (51%) recipients were alive and 125 (49%) had succumbed by June 2001. The necropsies were analyzed for EBV-related PTLD as evidenced by disseminated lymphocytic infiltrates labeled histochemically for antigens and RNA (EBER 1 and 2) detectable by in situ technology. From a subset of the PTLD cases (N=12) and a series of corresponding stem-cell recipient controls (N=36), consecutive samples of serum (N=103 and 364, respectively) were studied by qPCR for EBV-DNA, and the clinical data were reviewed.

RESULTS

The post-mortem analysis revealed 18 cases of PTLD (14% of the deceased), all of whom had received intensive immunosuppressive treatment including anti-thymocyte globulin for treatment or prophylaxis of graft versus host disease (GVHD). By using qPCR all the PTLD patients became EBV-DNA positive, in progressively rising copy numbers. EBV-DNA was first detectable 70 (median; range 24-154) days after SCT or 23 (4-86) days before death; i.e. earlier than the symptoms which appeared 15 (2-85) days before death. Among the SCT controls, EBV-DNA occurred sporadically (in only 3.9% sera).

CONCLUSIONS

qPCR for EBV-DNA in serum is a highly sensitive (100%) and specific (96%) diagnostic approach. Intensely immunosuppressed stem-cell recipients are at a great risk of developing PTLD, and should be carefully monitored for EBV-DNA, for pre-emptive treatment of this life-threatening disorder.