Lymphoproliferative disorders in immunocompromised individuals and therapeutic antibodies for treatment

The incidence of lymphoproliferative disease (LPD) is significantly higher in individuals who have congenital, acquired or iatrogenically induced immunodeficiency. Although there are a wide range of LPDs including lymphoma and leukemia, this article only covers LPDs in patients with impaired immune function, which are called immunodeficiency-associated LPDs (ID-LPDs). Three of the four ID-LPD categories recognized by WHO have been selected for discussion: LPD in primary immune disorders, post-transplant LPD and LPD in HIV infection. Because of the high incidence and mortality of ID-LPDs, careful evaluation of the morphology, immunophenotype, genotype, viral status and clinical history is required for accurate diagnosis and treatment. Recently, treatment with monoclonal antibodies (mAbs) has been widely used and developed because of its potential benefits. The aim of this review is to describe new information concerning mAb treatment in LPDs and to draw physicians’ attention to mAb therapy, which should be effective for some types of LPD.

Managing post-transplant lymphoproliferative disorders in solid-organ transplant recipients: a review of immunosuppressant regimens

Post-transplant lymphoproliferative disorders (PTLD) are a heterogeneous group of potentially life-threatening complications that occur after solid organ and bone marrow transplantation. Risk factors for acquiring PTLD are type of organ transplanted, age, intensity of immunosuppression, viral infections such as Epstein-Barr virus (EBV) and time after transplantation. Due to a dearth of well designed prospective trials, treatment for PTLD is often empirical, with reduction in immunosuppression accepted as the first step. Rituximab, a monoclonal antibody directed against the CD20 antigen of immature B cells, is often used as monotherapy after reduction in immunosuppression, although this is associated with a high risk of relapse if patients have at least one of the following risk factors: age greater than 60 years, elevated lactate dehydrogenase levels and Eastern Cooperative Oncology Group Score between 2 and 4. For such patients, rituximab should be considered in combination with CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone), particularly if high-grade PTLD is present. Although widely prescribed, the use of ganciclovir for PTLD remains controversial as EBV-transformed cells lack the thymidine kinase necessary for ganciclovir activation. Newer antivirals that combine ganciclovir with activators of cellular thymidine kinase have shown promising results in preclinical studies. In the absence of controlled trials, surgery may be indicated for localized disease and radiotherapy for patients with impending spinal cord compression or disease localized to the central nervous system or orbit. Future interventions may include adoptive immunotherapy, intravenous immunoglobulin, mammalian target of rapamycin inhibitors, monoclonal antibodies to interleukin-6 and galectin-1, and even EBV vaccination. Although several trials are in progress, it is necessary to wait for the long-term outcome of these studies on risk of PTLD relapse.

Post transplant lymphoproliferative disorders: risk, classification, and therapeutic recommendations

OPINION STATEMENT

Post transplant lymphoproliferative disorder (PTLD) is a heterogeneous disease that may occur in recipients of solid organ transplants (SOT) and hematopoietic stem cell transplant. The risk of lymphoma is increased 20-120% compared with the general population with risk dependent in part on level of immune suppression. In addition, recent data have emerged, including HLA and cytokine gene polymorphisms, regarding genetic susceptibility to PTLD. Based on morphologic, immunophenotypic, and molecular criteria, PLTD are classified into 4 pathologic categories: early lesions, polymorphic, monomorphic, and classical Hodgkin lymphoma. Evaluation by expert hematopathology is critical in establishing the diagnosis. The aim of therapy for most patients is cure with the concurrent goal of preservation of allograft function. Given the pathologic and clinical heterogeneity of PTLD, treatment is often individualized. A mainstay of therapy remains reduction of immune suppression (RI) with the level of reduction being dependent on several factors (e.g., history of rejection, current dosing, and type of allograft). Outside of early lesions and/or low tumor burden, however, RI alone is associated with cure in a minority of subjects. We approach most newly-diagnosed polymorphic and monomorphic PTLDs similarly using frontline single-agent rituximab (4 weeks followed by abbreviated maintenance) in conjunction with RI. Frontline combination chemotherapy may be warranted for patients with high tumor burden in need of prompt response or following failure of RI and/or rituximab. Due to chemotherapy-related complications in PTLD, especially infectious, we advocate comprehensive supportive care measures. Surgery or radiation may be considered for select patients with early-stage disease. For PTLD subjects with primary CNS lymphoma, we utilize therapeutic paradigms similar to immunocompetent CNS lymphoma using high-dose methotrexate-based therapy with concurrent rituximab therapy and sequential high-dose cytarabine. Finally, novel therapeutic strategies, especially adoptive immunotherapy, should continued to be explored.

Primary central nervous system post-transplant lymphoproliferative disorders following allogeneic hematopoietic stem cell transplantation

Post-transplant lymphoproliferative disorder (PTLD) is a serious complication after allogeneic hematopoietic stem cell transplantation (HSCT). Extra nodal involvement is common in PTLD, but isolated involvement of the central nervous system (CNS) is extremely rare. Given the rarity of primary CNS-PTLD there is no consensus on optimal treatment. We report a patient who developed Epstein-Barr virus related primary CNS-PTLD following allogeneic HSCT who was treated with the monoclonal anti-CD20 antibody rituximab and reduction of immunosuppression. In addition, we review the literature and discuss treatment options for patients with primary CNS-PTLD following allogeneic HSCT.

Report from a consensus conference on antibody-mediated rejection in heart transplantation

BACKGROUND

The problem of AMR remains unsolved because standardized schemes for diagnosis and treatment remains contentious. Therefore, a consensus conference was organized to discuss the current status of antibody-mediated rejection (AMR) in heart transplantation.

METHODS

The conference included 83 participants (transplant cardiologists, surgeons, immunologists and pathologists) representing 67 heart transplant centers from North America, Europe, and Asia who all participated in smaller break-out sessions to discuss the various topics of AMR and attempt to achieve consensus.

RESULTS

A tentative pathology diagnosis of AMR was established, however, the pathologist felt that further discussion was needed prior to a formal recommendation for AMR diagnosis. One of the most important outcomes of this conference was that a clinical definition for AMR (cardiac dysfunction and/or circulating donor-specific antibody) was no longer believed to be required due to recent publications demonstrating that asymptomatic (no cardiac dysfunction) biopsy-proven AMR is associated with subsequent greater mortality and greater development of cardiac allograft vasculopathy. It was also noted that donor-specific antibody is not always detected during AMR episodes as the antibody may be adhered to the donor heart. Finally, recommendations were made for the timing for specific staining of endomyocardial biopsy specimens and the frequency by which circulating antibodies should be assessed. Recommendations for management and future clinical trials were also provided.

CONCLUSIONS

The AMR Consensus Conference brought together clinicians, pathologists and immunologists to further the understanding of AMR. Progress was made toward a pathology AMR grading scale and consensus was accomplished regarding several clinical issues.

Post-transplant lymphoproliferative disorders following solid-organ transplantation

A post-transplant lymphoproliferative disorder (PTLD) is an uncommon but serious complication following solid-organ transplantation. The incidence varies, depending on the type of organ transplanted, the degree of immunosuppression, the number of episodes of acute rejection and a patient's immune status to Epstein-Barr virus. The incidence of PTLD is thought to be bimodal; cases in the first year after solid-organ transplantation are typically related to Epstein-Barr virus. A second incidence occurs more than 1 year following transplantation and is typically not related to Epstein-Barr virus. A variety of therapeutic approaches has been used for these patients, with more recent strategies including the use of rituximab, with or without combination chemotherapy. Efforts continue to be made to improve the outcome of patients with PTLD.

Management of posttransplant lymphoproliferative disorders following solid organ transplant: an update

Development of secondary malignancies is a well-known complication of solid organ transplant, with skin cancer and lymphoproliferative disorders being most frequently observed. Posttransplant lymphoproliferative disorders, caused by diminished immune surveillance, represent a broad spectrum of pathological and clinical disorders, ranging from benign conditions to very aggressive lymphomas. Here we review treatment options for adult patients experiencing posttransplant lymphoproliferative disorders following solid organ transplant.

Reduction of immunosuppression as initial therapy for posttransplantation lymphoproliferative disorder(★)

Reduction of immunosuppression (RI) is commonly used to treat posttransplant lymphoproliferative disorder (PTLD) in solid organ transplant recipients. We investigated the efficacy, safety and predictors of response to RI in adult patients with PTLD. Sixty-seven patients were managed with RI alone and 30 patients were treated with surgical excision followed by adjuvant RI. The response rate to RI alone was 45% (complete response-37%, partial response-8%). The relapse rate in complete responders was 17%. Adjuvant RI resulted in a 27% relapse rate. The acute rejection rate following RI-containing strategies was 32% and a second transplant was feasible without relapse of PTLD. The median survival was 44 months in patients treated with RI alone and 9.5 months in patients who remained on full immunosuppression (p = 0.07). Bulky disease, advanced stage and older age predicted lack of response to RI. Survival analysis demonstrated predictors of poor outcome-age, dyspnea, B symptoms, LDH level, hepatitis C, bone marrow and liver involvement. Patients with none or one of these factors had a 3-year overall survival of 100% and 79%, respectively. These findings support the use of RI alone in low-risk PTLD and suggest factors that predict response and survival.

Lymphoproliferative disorders after solid organ transplantation-classification, incidence, risk factors, early detection and treatment options

Posttransplant lymphoproliferative disorder (PTLD) is a heterogeneous disease group of benign and malignant entities. The new World Health Organisation classification introduced in 2008 distinguishes early lesions, polymorphic, monomorphic and classical Hodgkin lymphoma-type PTLD. Based on the time of appearance, early and late forms can be identified.PTLDs are the second most frequent posttransplantation tumors in adulthood, and the most frequent ones in childhood. The incidence varies with the transplanted organ-from 1%-2% following kidney transplantation to as high as 10% following thoracic organ transplantation-due to different intensities in immunosuppression. Immunocompromised state and Epstein-Barr virus (EBV) infection are the two major risk factors.In Europe and the US approximately 85% of PTLDs are of B-cell origin, and the majority are EBV-associated. Symptoms are often unspecific; extranodal, organ manifestations and central nervous system involvement is common. Early lesions respond well to a decrease in immunosuppression. Malignant entities are treated with rituximab, chemotherapy, radiotherapy and surgical therapy. Adoptive T-cell transfer represents a promising therapeutic approach. The prognosis is favorable in early PTLD, and poor in late PTLD. Five-year survival is 30% for high-grade lymphomas. The prognosis of EBV-negative lymphomas is worse.Lowering the risk of PTLD may be achieved by low dose maintenance immunosuppression, immunosuppressive drugs inhibiting cell proliferation, and special immunotherapy (e.g. interleukin-2 inhibitors). Early detection is especially important for high risk-e.g. EBV-negative-patients, where the appearance of EBV-DNA and the increase in its titer may help.

Immunotherapeutic options for Epstein-Barr virus-associated lymphoproliferative disease following transplantation

Epstein-Barr virus-associated lymphoproliferative diseases (EBV-LPD) after hematopoietic stem cell transplantation or solid-organ transplantation remain a serious and potentially life-threatening complication. In the last decade, outcomes for EBV-LPD have significantly improved. Key to this success was the development of early detection methods, such as serial measurements of EBV-DNA load in the peripheral blood of transplant recipients. Immunotherapeutic interventions for EBV-LPD include reduction of immunosuppression, CD20 monoclonal antibodies (rituximab) as monotherapy or in conjunction with chemotherapy, and adoptive immunotherapy with EBV-specific T cells. Pre-emptive immunotherapeutic interventions can prevent the development of EBV-LPD. As monotherapy, immunotherapy is effective in inducing remissions of EBV-LPD with low-risk features. For high-risk disease, combining immunotherapy with conventional therapies has led to superior outcomes. Current challenges consist of risk stratifying patients so that patients receive the most efficacious therapy without suffering from unwanted side effects.

Treatment advances in posttransplant lymphoproliferative disease

PURPOSE OF REVIEW

Epstein-Barr virus-associated posttransplant lymphoproliferative disease (PTLD) is a life-threatening complication of organ transplantation. As we continue to observe improved outcomes of patients living after solid or hematopoietic stem cell transplantation, we can expect to see a parallel increase in the incidence of PTLD. Several innovative therapeutic approaches are currently under development to add to our arsenal of treatment strategies in this devastating disease.

RECENT FINDINGS

The past decade has witnessed significant progress in the understanding and treatment of PTLD. The tolerability and effectiveness of standard treatment regimens, such as a reduction in immunosuppression, rituximab, and chemotherapy, have been confirmed and improved upon. Newer options for treatment demonstrating significant promise include antiviral therapy with arginine butyrate, as well as Epstein-Barr virus-specific cytotoxic T-cell therapy.

SUMMARY

Both the heterogeneous PTLD population and the lack of standardized and evidence-based treatment approaches make treatment a difficult decision for the clinician. This article reviews and updates the evidence behind accepted strategies such as reduction in immunosuppression, rituximab, and chemotherapy, as well as explores novel and effective therapeutic modalities including antiviral therapy with arginine butyrate and adoptive allogeneic T-cell therapy.

Post-transplant Burkit t's Leukemia or Lymphoma. Study of Five Cases Treated with Specific Intensive Therapy (PETHEMA ALL-3/97 Trial)

Burkitt's lymphoma (BL) and Burkitt-like acute lymphoblastic leukemia (ALL) are uncommon lymphoproliferative disorders after solid organ or stem cell transplantation. Although their prognosis is considered to be poor, there are scarce data on the clinical characteristics and the response to specific therapies. We report the main clinical characteristics and the results of a specific intensive chemotherapy in 5 adult patients with postransplant BL/ALL3 included in the PETHEMA ALL3/97 protocol. Two patients died in induction, another died in consolidation phase and the remaining 2 patients are in continuous complete remission 6 and 18 months from the diagnosis.

Epstein-Barr virus-associated lymphoproliferative disease after allogeneic haematopoietic stem cell transplantation: molecular monitoring and early treatment of high-risk patients

PURPOSE OF REVIEW

Epstein-Barr virus-associated lymphoproliferative disease (EBV-LPD) is a rare but serious complication in recipients of allogeneic stem cell transplants. An overview is given of the incidence, monitoring and (early) treatment of EBV-LPD.

RECENT FINDINGS

The most important risk factor for EBV-LPD is the use of in-vivo T-cell depletion with antithymocyteglobulin. In addition, alternative donor stem cell transplantation is associated with an increased risk for EBV-LPD. Monitoring of EBV DNA in high-risk patients and subsequent early treatment is very successful, resulting in a low EBV-associated mortality. The monitoring of EBV-specific cytotoxic T lymphocytes might further increase the positive predictive value of EBV DNAemia for EBV-LPD. Once overt EBV-LPD has been diagnosed, rituximab treatment is indicated, guided by monitoring of EBV DNA. The infusion of donor lymphocytes is highly effective, but may be complicated by graft-versus-host disease. Therefore, the infusion of T cells, which have been depleted of alloreactive cells, is currently receiving attention.

SUMMARY

EBV DNA levels should be monitored in patients with high-risk features. Early treatment may be instituted at predefined DNA levels (preemptive approach) or at the earliest signs of LPD (prompt approach). Stepwise treatment guided by EBV DNA, including interruption of immunosuppression, rituximab, and adoptive T-cell immunotherapy may all add to the low mortality currently associated with LPD following allogeneic stem cell transplantation.

[Anti-CD20 in hematologic oncology]

Twelve years ago, rituximab, a chimeric monoclonal anti-CD20 antibody, became available for the treatment of relapsing follicular lymphoma. It has resulted in an improvement of approximately 20% in survival for nearly all B cell lymphomas. In follicular lymphoma, rituximab combined with chemotherapy is indicated as first-line treatment when treatment is necessary. It is also an interesting option, alone or in combination with chemotherapy for the treatment of relapses, after verifying the persistence of CD20 expression on the surface of malignant cells. As a maintenance treatment after chemotherapy with or without rituximab, it improves relapse-free survival and overall survival. The standard treatment for high-grade diffuse lymphoma, regardless of age and regardless of predicted severity, is now the combination of CHOP chemotherapy and rituximab. The combination of fludarabine, cyclophosphamide, and rituximab is currently the reference treatment for chronic lymphoid leukemia as first-line treatment for patients with few comorbidities and for those with relapses. The role of this antibody in the treatment of more serious forms of lymphoma is under evaluation. The administration of rituximab, alone or in combination, in the treatment of low-grade non-follicular lymphoma must be decided as a function of existing protocols in multidisciplinary consultations. New-generation anti-CD20 antibodies, designed to improve still further the already remarkable efficacy/toxicity ratio, are now taking the road that rituximab opened.

Immunotherapy targeting EBV-expressing lymphoproliferative diseases

Epstein-Barr virus (EBV) is associated with non-Hodgkin's lymphoma (NHL), occurring in immunocompetent individuals as well as those with immunodeficiency. In patients with immunodeficiency, the nature of EBV infection in the malignant cell determines the pattern of antigen expression and the associated presence of targets for cellular immunotherapy. EBV-expressing lymphoma cells in the setting of immunodeficiency express type III latency, characterized by expression of all nine latent-cycle EBV antigens, and strategies to restore EBV-specific immune responses have resulted in effective anti-tumour activity. In contrast, EBV-associated NHL in immunocompetent individuals is characterized by type II latency, where a more restricted array of EBV-associated antigens is expressed. In this setting, T-cell therapies are limited by inadequate persistence of transferred T cells and by tumour-evasion strategies. A number of strategies to genetically modify the infused T cells and modulate the host environment are under evaluation.

NK cell-mediated lysis is essential to kill Epstein-Barr virus transformed lymphoblastoid B cells when using rituximab

Rituximab is a humanized chimeric monoclonal antibody, targeted against the pan B cell marker CD20. It is frequently used to treat a variety of B cell lymphomas and immunosuppression associated lymphoproliferations such as posttransplant lymphoproliferative disorder (PTLD). The response rate of rituximab treatment is 65%, but the exact in vivo mechanism of action is not yet fully understood, although antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and direct induction of apoptosis have been suggested as effector mechanism. Rituximab may affect different types of lymphomas through different mechanisms. As lymphoblastoid cell lines (LCLs) are well-established in vitro models of PTLD, we investigated the effect of rituximab on these cells using a custom built automated laser confocal fluorescent microscope. We found that rituximab alone was not effective at inducing cell death of EBV-transformed B cells. The antibody was effective in the complement-mediated CDC. Rituximab could induce NK cell-mediated ADCC but it was more effective in the presence of untreated fresh human plasma compared to heat-inactivated human plasma. Our data suggest that complement-enhanced NK-mediated ADCC is required for effective rituximab mediated killing of EBV-transformed B cells. Determining and monitoring of serum complement levels and in vitro killing efficacy of NK cells of PTLD patients might help to predict resistant cases to rituximab therapy. On the other hand our results suggest a possibility that rituximab should be combined only with cytotoxic drugs that spare NK function when treating PTLD patients.

EBV+ lymphoproliferative disease following prolonged chemotherapy for refractory LCH

Epstein-Barr virus (EBV) is a herpesvirus for which latent infection in B lymphocytes occurs in most individuals by middle childhood. Clinically significant reactivation of this virus occurs in the context of suppressed cell-mediated immunity, occasionally developing into lymphoproliferative disease (EBV-LPD). EBV reactivation is rarely associated with intensive chemotherapy alone. Here we present the case of a 4-year-old female who developed EBV-LPD as a complication of prolonged immunosuppressive chemotherapy for her multiply-recurrent Langerhans cell histiocytosis (LCH).

The management of posttransplant lymphoproliferative disorder

Posttransplant lymphoproliferative disorder (PTLD) is a life-threatening complication of allogeneic hematopoietic stem cell and solid organ transplantation. Most cases are EBV-positive B-cell neoplasms, which occur in the setting of pharmacologically impaired cellular immunity. Several different treatment strategies including cytotoxic antitumor therapy, anti-B-cell monoclonal antibody therapy, antiviral therapy, and modalities aimed at restoration of EBV-specific cellular immunity have been employed. In addition, efforts to identify patients at high risk for PTLD have resulted in attempts at prophylactic and preemptive therapies. In this review we discuss the available literature on differing approaches to PTLD management, identify areas in need of further investigation, and, when possible, make general recommendations. Reduction of immunosuppression remains the mainstay of first-line treatment. Accumulating evidence supports the role of rituximab as second-line therapy with cytotoxic chemotherapy reserved for specific circumstances. Further investigations are needed to better define the role of more novel and less widely available therapies such as the adoptive transfer of EBV-specific T cells and optimization of antiviral therapies.

Preemptive therapy of EBV-related lymphoproliferative disease after pediatric haploidentical stem cell transplantation

The treatment of Epstein-Barr virus (EBV)-related post-transplant lymphoproliferative disease (PTLD) after hematopoietic stem cell transplantation (HSCT) is still unsatisfactory. We conducted a prospective trial to evaluate the impact of routine EBV surveillance and preemptive treatment with the anti-CD20 monoclonal antibody rituximab on the development of PTLD in pediatric recipients of extensively T-cell depleted HSCT from an HLA-haploidentical relative. Twenty-seven patients were included in the surveillance program, 12 developed EBV DNA positivity, with 8 of 12 presenting with sustained viral DNA levels requiring treatment with rituximab. Treatment was well tolerated, and induced clearance of EBV DNA in all patients. However, 4/8 patients showed a new increase in EBV load, coincident with the emergence of CD20(-)/CD19(+) B cells in peripheral blood, accompanied by overt PTLD in 3 patients. The latter cleared PTLD after receiving donor EBV-specific cytotoxic T-lymphocytes (CTLs), and persist in remission at a median 30-month follow-up. EBV-specific T-cell frequency, undetectable at time of EBV DNA positivity, was restored by T-cell therapy to levels comparable with controls. We conclude that preemptive therapy with rituximab is safe, but only partly effective in haplo-HSCT recipients. Patients who progress to PTLD under rituximab treatment can be rescued permanently by infusion of EBV-specific CTLs.

Rituximab therapy in malignant lymphoma

Rituximab is the first monoclonal antibody to have been registered for the treatment of B-cell lymphomas. Randomized studies have demonstrated its activity in follicular lymphoma (FL), mantle cell lymphoma and diffuse large B-cell lymphoma (DLBCL) in untreated or relapsing patients. Non-comparative studies have shown an activity in all other lymphomas. Because of its high activity and low toxicity ratio, rituximab has transformed the outcome of patients with B-cell lymphoma. A combination of rituximab plus chemotherapy, rituximab+cyclophosphamide+doxorubicin+vincristine+prednisolone (R-CHOP), has the highest efficacy ever described with any chemotherapy in DLBCL and FL. Some patients are refractory to rituximab but the precise mechanisms of this refractoriness are not understood.

Cytotoxic drug sensitivity of Epstein-Barr virus transformed lymphoblastoid B-cells

BACKGROUND

Epstein-Barr virus (EBV) is the causative agent of immunosuppression associated lymphoproliferations such as post-transplant lymphoproliferative disorder (PTLD), AIDS related immunoblastic lymphomas (ARL) and immunoblastic lymphomas in X-linked lymphoproliferative syndrome (XLP). The reported overall mortality for PTLD often exceeds 50%. Reducing the immunosuppression in recipients of solid organ transplants (SOT) or using highly active antiretroviral therapy in AIDS patients leads to complete remission in 23-50% of the PTLD/ARL cases but will not suffice for recipients of bone marrow grafts. An additional therapeutic alternative is the treatment with anti-CD20 antibodies (Rituximab) or EBV-specific cytotoxic T-cells. Chemotherapy is used for the non-responding cases only as the second or third line of treatment. The most frequently used chemotherapy regimens originate from the non-Hodgkin lymphoma protocols and there are no cytotoxic drugs that have been specifically selected against EBV induced lymphoproliferative disorders.

METHODS

As lymphoblastoid cell lines (LCLs) are well established in vitro models for PTLD, we have assessed 17 LCLs for cytotoxic drug sensitivity. After three days of incubation, live and dead cells were differentially stained using fluorescent dyes. The precise numbers of live and dead cells were determined using a custom designed automated laser confocal fluorescent microscope.

RESULTS

Independently of their origin, LCLs showed very similar drug sensitivity patterns against 29 frequently used cytostatic drugs. LCLs were highly sensitive for vincristine, methotrexate, epirubicin and paclitaxel.

CONCLUSION

Our data shows that the inclusion of epirubicin and paclitaxel into chemotherapy protocols against PTLD may be justified.

Long-term survival in post-transplant lymphoproliferative disorders with a dose-adjusted ACVBP regimen

Post-transplant lymphoproliferative disorders (PTLD) are severe complications after solid organ transplantation with no consensus on best treatment practice. Chemotherapy is a therapeutic option with a high response and a significant relapse rate leading to a low long-term tolerance rate. Currently, most centres use anthracycline-based drug combinations, such as CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone). We assessed the efficacy and safety of a dose-adjusted ACVBP (doxorubicin reduced to 50 mg/m(2), cyclophosphamide adjusted to renal function, vindesine, bleomycin, prednisone) regimen in patients failing to respond to a reduction in immunosuppressive therapy. Favourable responses were observed in 24 (73%) of the 33 treated patients. Fourteen (42%) patients died, mostly from PTLD progression. Actuarial survival was 60% at 5 years and 55% at 10 years. Survival prognostic factors were: number of involved sites (P = 0.007), clinical stage III/IV (P = 0.004), bulky tumour (P < 0.0001), B symptoms (P = 0.03), decreased serum albumin (P = 0.03) and poor performance status (P = 0.06). Both the international and the PTLD prognostic index were predictive for survival (P = 0.001 and P = 0.002, respectively). Overall 128 cycles were given. Grade 3 or 4 neutropenia was recorded after 26 (20%) chemotherapy cycles in 19 (58%) patients. Forty-one (32%) infections were recorded in 26 (79%) patients. This study demonstrated that an individual dose-adjustment of ACVBP regimen was manageable in PTLD patients and favourably impacted on long-term survival.

A comparison of quantitative-competitive and realtime PCR assays using an identical target sequence to detect Epstein-Barr virus viral load in the peripheral blood

Monitoring the load of Epstein-Barr virus (EBV) in the peripheral blood by quantitative PCR has been accepted as a useful tool for predicting the onset of EBV related diseases, confirming an EBV disease diagnosis and following the response to treatment interventions. In the present study, the use of a realtime polymerase chain reaction (rt-PCR) assay developed for unpurified cell preparations was examined and the results of the realtime assay were compared to an EBV quantitative-competitive PCR assay (QC-PCR). Both assays use the same target sequence and the same method for determining the standard value for the copy number of EBV genomes present. A comparison of 572 PCR results reveals that the realtime assay gave 5-10-fold higher values than the QC-PCR. Fifty-one results (8.9%) were discordant between the two sets of data. The most commonly encountered discordant result was detection of low amounts of EBV DNA by the rt-PCR assay that were not detected in specimens by QC-PCR. The two assays had a high degree of correlation across the range of load detection allowing clinically relevant threshold values determined in the QC-PCR assay to be inferred for the rt-PCR assay. External normalization of the rt-PCR assay was determined to be an important tool for monitoring the quality and/or quantity of human DNA in the starting material. rt-PCR assays with unpurified cell lysates compare favorably with quantitative-competitive assays and when normalized offer real advantages in specimen preparation, assay manipulations and reproducibility over both quantitative-competitive assays and realtime assays that require purified nucleic acid inputs.

Review of Epstein–Barr virus and post-transplant lymphoproliferative disorder post-solid organ transplantation (Review Article)

Post-transplant lymphoproliferative disorder (PTLD) following solid organ transplantation is an important form of post-transplant malignancy. PTLD is typically associated with Epstein-Barr virus (EBV) and occurs in the setting of profound immunosuppression resulting in a deficiency of EBV-specific cytotoxic T lymphocytes (CTL). Predisposing factors include EBV mismatch between donor and recipient, use of immunosuppression especially T-cell depletive therapies and genetic predisposition of recipients. The standard approach has been to reduce immunosuppression but is often insufficient to induce tumour regression. Further understanding of the immunobiology of PTLD has resulted in improved monitoring techniques (including EBV viral load determined by polymerase chain reaction) and newer treatment options. Recent work has highlighted a potential role for dendritic cells in both the pathogenesis and treatment of PTLD. Current treatment modalities include adoptive immunotherapy using ex vivo generated autologous EBV-specific CTL or allogeneic CTL, cytokine therapies, antiviral agents, and more recently, rituximab and dendritic-cell based therapies. This review focuses on the developments and progress in the pathogenesis, diagnosis and treatment of PTLD.

How useful is PET/CT imaging in the management of post-transplant lymphoproliferative disease after liver transplantation?

Post-transplant lymphoproliferative disease (PTLD) is a serious and potentially life-threatening complication after solid organ transplantation. Here, we report our first experience with the use of PET/CT (positron emission tomography combined with computed tomogram) for the management of patients with PTLD after liver transplantation. Four patients with histologically proven PTLD were analyzed. Conventional work-up included physical examination and head-to-pelvis CT. PET/CT was used in one patient for initial staging and in all patients for follow-up. PET/CT positive findings underwent biopsy. Information provided by PET/CT resulted in a change of medical management in three of the four patients. Conventional work-up missed residual disease after surgery in one and failed to detect a tumor relapse in another patient. However, one patient disclosed a false positive PET/CT finding in the lungs. In conclusion, PET/CT may be a useful tool for staging and therapy monitoring of PTLD after liver transplantation.

Posttransplant Lymphoproliferative Disorders in Liver Transplanted Patients: A Report of Four Cases

BACKGROUND

Posttransplant lymphoproliferative disorders (PTLDs) are an uncommon but important cause of morbidity and mortality in solid organ transplant recipients. They are often the result of Epstein-Barr virus (EBV)-induced proliferation of B-lymphocytes in the setting of immunosuppression.

PATIENTS AND METHODS

We retrospectively analyzed four cases of PTLD after liver transplantation. In all patients immunosuppression was reduced and anti-CD20 monoclonal antibody (rituximab) was administered. In two of four patients, EBV viral load was positive in the peripheral blood, and gancyclovir was therefore also prescribed. Chemotherapy (CHOP) was used as a rescue in the event of treatment failure.

RESULTS

Even if no severe adverse events were observed during the treatment period, our treatment approach to PTLD was not effective, and only one patient out of four is still alive.

CONCLUSIONS

Well-designed clinical trials are necessary to evaluate the role of this combined approach in the treatment of PTLD in liver transplant recipients.

Sirolimus-Induced Remission of Posttransplantation Lymphoproliferative Disorder

Posttransplantation lymphoproliferative disorder (PTLD) is one of the most serious complications of solid-organ transplantation. It potentially is treatable in most cases, but current methods involve withdrawal or reduction of immunosuppression and the consequent risk for graft rejection. Sirolimus was shown in vivo and in vitro to limit proliferation of a number of malignant cell lines, including those of PTLD-derived cells. We present a case of disseminated PTLD in a patient with a renal transplant that resolved completely with conversion of immunosuppression to sirolimus. Graft function was maintained and improved with treatment. This offers a novel means of treating these patients and minimizing transplant loss.

Epstein-Barr virus reactivation in a patient treated with anti-thymocyte globulin for severe aplastic anemia

Epstein-Barr virus (EBV) infection and reactivation is an increasing complication in immune deficient patients, particularly after allogeneic hematopoietic stem cell transplantation (HSCT). Therapy with anti-thymocyte globulin (ATG) is associated with higher incidence of EBV-related disease in HSCT patients, but this risk is not documented in patients receiving ATG for severe aplastic anemia (SAA). We describe the case of a patient who developed an EBV infection, with the clinical features of an infectious mononucleosis, after immune suppression with cyclosporine and two courses of ATG for SAA.

Epstein-Barr virus-associated post-transplant lymphoproliferative disease with central nervous system involvement after unrelated allogeneic hematopoietic stem cell transplantation

Post-transplant lymphoproliferative disorders (PTLD) represent an heterogeneous group of abnormal lymphoid proliferation related to Epstein-Barr virus (EBV) reactivation that arise early after allogeneic hematopoietic stem cell transplant (HSCT). PLTD with central nervous system (CNS) involvement has been reported in few cases. We describe the case of a 31-year-old-man who developed an EBV-related PTLD with CNS involvement 2 months after an allogeneic unrelated HSCT for acute myeloid leukemia in first complete remission who was successfully treated with rituximab, cidofovir and intrathecal infusion of methotrexate and methylprednisolone.

Management of patients with post-transplant lymphoproliferative disorder: the role of rituximab

Post-transplant lymphoproliferative disorder (PTLD) is a serious complication of solid organ and bone marrow transplantations. Rituximab (Rituxan, Mabthera), a chimeric monoclonal antibody to the CD20 antigen on the surface of B-cell lymphocytes, has been used increasingly in the treatment of PTLD. Rituximab was initially approved for the treatment of low-grade non-Hodgkin lymphomas, but multiple case studies, retrospective analyses, and phase II trials demonstrate the benefit of rituximab in PTLD. This paper reviews the current data on rituximab and its promising role in the management of PTLD.

Epstein-Barr virus-associated lymphomas

Following Epstein and colleagues' ground-breaking discovery of Epstein-Barr virus by electron microscopy of Burkitt's lymphoma cell lines, there came the observation that Epstein-Barr virus induces immortalization of B cells in vitro. Thus, initial hopes were of a virus confined to equatorial Africa with a causal link to a particular subtype of childhood lymphoma. Over the past 40 years there has been great progress towards understanding the biology and epidemiology of Epstein-Barr virus, which conclusively show that these early ideas were overly simplistic. It is now known that Epstein-Barr virus has a seroprevalence of approximately 95% worldwide, and persists for life within host B lymphocytes. Infection in New World primates leads to lymphoma and inoculation of peripheral blood mononuclear cells from Epstein-Barr virus-seropositive subjects into severe combined immunodeficiency mice results in B-cell lymphoproliferative disorders. Epstein-Barr virus is now known to be implicated in a range of lymphoid and other malignancies, and this association will be the subject of this review.