Characteristics of early and late PTLD development in pediatric solid organ transplant recipients. Transplantation. 2013;95:240-246. [PMID: 23222898 DOI: 10.1097/tp.0b013e318277e344]

Cytotoxic T-lymphocyte therapy for post-transplant lymphoproliferative disorder after solid organ transplantation in children

EBV-CTL immunotherapy targets EBV antigens expressed by tumor cells in PTLD. Data on outcome of EBV-CTL in pSOT patients are limited. The aim of the study is to describe our experience with allogeneic, third-party EBV-CTL for the treatment of PTLD in pSOT patients in a single tertiary center. Retrospective review was performed of all pSOT patients who received EBV-CTL for PTLD. PTLD was diagnosed using World Health Organization histologic criteria. EBV-CTLs were derived from human leukocyte antigen-typed, EBV-seropositive third-party donors, and cryopreserved and maintained by an accredited national blood transfusion service. Ten patients received EBV-CTL for histologically proven PTLD from 1999 to 2016 following liver (n=5), combined intestinal/liver (n=4), and liver/kidney (n=1) transplantation. PTLD occurred at median age of 40 months (range: 12-144) and median post-transplant interval of 8 months (range: 2-107). Seven had monomorphic, two had polymorphic, and one had Hodgkin-type PTLD. All were of B-cell origin and EBV-positive on histology. EBV-CTL achieved an overall remission rate of 80% (8 of 10). Transient adverse effects included fever, tachycardia, and vomiting. None developed graft-versus-host disease or opportunistic infections. EBV-CTL is an effective treatment for PTLD in pSOT patients, with good remission rate and minimal toxicity.

Comprehensive review of post-organ transplant hematologic cancers

A higher risk for a variety of cancers is among the major complications of posttransplantation immunosuppression. In this part of a continuing series on cancers posttransplantation, this review focuses on the hematologic cancers after solid organ transplantation. Posttransplantation lymphoproliferative disorders (PTLDs), which comprise the great majority of hematologic cancers, represent a spectrum of conditions that include, but are not limited to, the Hodgkin and non-Hodgkin lymphomas. The oncogenic Epstein-Barr virus is a key pathogenic driver in many PTLD cases, through known and unknown mechanisms. The other hematologic cancers include leukemias and plasma cell neoplasms (multiple myeloma and plasmacytoma). Clinical features vary across malignancies and location. Preventive screening strategies have been attempted mainly for PTLDs. Treatments include the chemotherapy regimens for the specific cancers, but also include reduction of immunosuppression, rituximab, and other therapies.

Personalized adoptive immunotherapy for patients with EBV-associated tumors and complications: Evaluation of novel naturally processed and presented EBV-derived T-cell epitopes

Morbidity and mortality of immunocompromised patients are increased by primary infection with or reactivation of Epstein-Barr virus (EBV), possibly triggering EBV⁺ post-transplant lymphoproliferative disease (PTLD). Adoptive transfer of EBV-specific cytotoxic T cells (EBV-CTLs) promises a non-toxic immunotherapy to effectively prevent or treat these complications. To improve immunotherapy and immunomonitoring this study aimed at identifying and evaluating naturally processed and presented HLA-A*03:01-restricted EBV-CTL epitopes as immunodominant targets. More than 15000 peptides were sequenced from EBV-immortalized B cells transduced with soluble HLA-A*03:01, sorted using different epitope prediction tools and eleven candidates were preselected. T2 and Flex-T peptide-binding and dissociation assays confirmed the stability of peptide-MHC complexes. Their immunogenicity and clinical relevance were evaluated by assessing the frequencies and functionality of EBV-CTLs in healthy donors (n > 10) and EBV⁺ PTLD-patients (n = 5) by multimer staining, Eli- and FluoroSpot assays. All eleven peptides elicited EBV-CTL responses in the donors. Their clinical applicability was determined by small-scale T-cell enrichment using Cytokine Secretion Assay and immunophenotyping. Mixtures of these peptides when added to the EBV Consensus pool revealed enhanced stimulation and enrichment efficacy. These EBV-specific epitopes broadening the repertoire of known targets will improve manufacturing of clinically applicable EBV-CTLs and monitoring of EBV-specific T-cell responses in patients.

The Immune Response to Epstein Barr Virus and Implications for Posttransplant Lymphoproliferative Disorder

Posttransplant lymphoproliferative disorder (PTLD) is a serious complication in organ transplant recipients and is most often associated with the Epstein Barr virus (EBV). EBV is a common gammaherpes virus with tropism for B lymphocytes and infection in immunocompetent individuals is typically asymptomatic and benign. However, infection in immunocompromised or immunosuppressed individuals can result in malignant B cell lymphoproliferations, such as PTLD. EBV+ PTLD can arise after primary EBV infection, or because of reactivation of a prior infection, and represents a leading malignancy in the transplant population. The incidence of EBV+ PTLD is variable depending on the organ transplanted and whether the recipient has preexisting immunity to EBV but can be as high as 20%. It is generally accepted that impaired immune function due to immunosuppression is a primary cause of EBV+ PTLD. In this overview, we review the EBV life cycle and discuss our current understanding of the immune response to EBV in healthy, immunocompetent individuals, in transplant recipients, and in PTLD patients. We review the strategies that EBV uses to subvert and evade host immunity and discuss the implications for the development of EBV+ PTLD.

Incidental EBV-positivity in paediatric post-transplant specimens demonstrates the need for stringent criteria for diagnosing post-transplant lymphoproliferative disorders

AIMS

To examine the need for minimal diagnostic criteria for post-transplant lymphoproliferative disorders (PTLD) in children, we sought to determine the rate of incidental Epstein-Barr virus (EBV)-positivity in tissues from organ transplant recipients (OTR).

METHODS

EBV in situ hybridisation (ISH) was done retrospectively on tissue from 34 paediatric autopsies of OTR and paediatric tonsillectomy specimens from non-OTR (96) and OTR (6). Patients with a history of PTLD were excluded from both data sets.

RESULTS

EBV-positivity was found incidentally in 2/34 autopsy cases (5.9%). Median time from transplant to death for all patients was 12.8 months (range 0.1-153 months). Median time between transplant and death in EBV-positive cases was 34 months. EBV was positive in 26/102 tonsils (25%). Among tonsils from OTR, 4/6 (67%) were EBV-positive.

CONCLUSIONS

These findings reinforce the need for strict morphological and clinical criteria, other than EBV-positivity, when diagnosing PTLD in the paediatric population.

Current Trends and Alternative Scenarios in EBV Research

Epstein-Barr virus (EBV) infection is associated with several distinct hematological and epithelial malignancies, e.g., Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma, gastric carcinoma, and others. The association with several malignant tumors of local and worldwide distribution makes EBV one of the most important tumor viruses. Furthermore, because EBV can cause posttransplant lymphoproliferative disease, transplant medicine has to deal with EBV as a major pathogenic virus second only to cytomegalovirus. In this review, we summarize briefly the natural history of EBV infection and outline some of the recent advances in the pathogenesis of the major EBV-associated neoplasms. We present alternative scenarios and discuss them in the light of most recent experimental data. Emerging research areas including EBV-induced patho-epigenetic alterations in host cells and the putative role of exosome-mediated information transfer in disease development are also within the scope of this review. This book contains an in-depth description of a series of modern methodologies used in EBV research. In this introductory chapter, we thoroughly refer to the applications of these methods and demonstrate how they contributed to the understanding of EBV-host cell interactions. The data gathered using recent technological advancements in molecular biology and immunology as well as the application of sophisticated in vitro and in vivo experimental models certainly provided deep and novel insights into the pathogenetic mechanisms of EBV infection and EBV-associated tumorigenesis. Furthermore, the development of adoptive T cell immunotherapy has provided a novel approach to the therapy of viral disease in transplant medicine and hematology.

Persistent Epstein-Barr viral load in Epstein-Barr viral naïve pediatric heart transplant recipients: Risk of late-onset post-transplant lymphoproliferative disease

AIM

To examine the risk of late-onset post-transplant lymphoproliferative disorder (PTLD) in the presence of persisting high Epstein-Barr virus (EBV) in EBV naïve pediatric heart transplant (HT) recipients.

METHODS

A retrospective review of the medical records of the 145 pediatric HT recipients who had serial EBV viral load monitoring at our center was performed. We defined EBV naive patients whose EBV serology either IgM or IgG in the blood were negative at the time of HT and excluded passive transmission from mother to child in subjects less than 6 mo of age.

RESULTS

PTLD was diagnosed in 8 out of 145 patients (5.5%); 6/91 (6.5%) in those who were EBV seropositive and 2/54 (3.7%) in the EBV naïve group at the time of HT (P = 0.71). We found 32/145 (22%) patients with persistently high EBV load during continuing follow-up; 20/91 (22%) in EBV seropositive group vs 12/54 (22%) in EBV naïve group (P = 0.97). There was no significant association between pre-HT serostatus and EBV load after transplant (P > 0.05). In the EBV seropositive group, PTLD was diagnosed in 15% (3/20) of patients with high EBV vs 4.2% (3/71) of patients with low or undetectable EBV load (P = 0.14) whereas in EBV naïve patients 8.3% (1/12) of those with high EBV load and 2.3% (1/42) with low or undetectable EBV load (P = 0.41). There was a highly significant association between occurrence of PTLD in those with high EBV load and duration of follow up (4.3 ± 3.9 years) after HT by Cochran-Armitage test for the entire cohort (P = 0.005). At least one episode of acute rejection occurred in 72% (23/32) of patients with high EBV vs 36% (41/113) patients with low or undetectable EBV after HT (P < 0.05).

CONCLUSION

There is an association between persistently high EBV load during post-HT follow up and the occurrence of late-onset PTLD in pediatric HT recipients irrespective of serostatus at the time of transplant. The occurrence of allograft rejection increased in patients with high EBV load presumably due to reduction in immunosuppression.

Matched-pair analysis: identification of factors with independent influence on the development of PTLD after kidney or liver transplantation

BACKGROUND

Post-transplant lymphoproliferative disorder (PTLD) adversely affects patients' long-term outcome.

METHODS

The paired t test and McNemar's test were applied in a retrospective 1:1 matched-pair analysis including 36 patients with PTLD and 36 patients without PTLD after kidney or liver transplantation. Matching criteria were age, gender, indication, type of transplantation, and duration of follow-up. All investigated PTLD specimen were histologically positive for EBV. Risk-adjusted multivariable regression analysis was used to identify independence of risk factors for PTLD detected in matched-pair analysis. The resultant prognostic model was assessed with ROC-curve analysis.

RESULTS

Patients suffering with PTLD had shorter mean survival (p = 0.004), more episodes of CMV infections or reactivations (p = 0.042), and fewer recipient HLA A2 haplotypes (p = 0.007), a tacrolimus-based immunosuppressive regimen (p = 0.052) and higher dosages of tacrolimus at hospital discharge (Tac dosage) (p = 0.052). Significant independent risk factors for PTLD were recipient HLA A2 (OR = 0.07, 95 % CI = 0.01-0.55, p = 0.011), higher Tac dosages (OR = 1.29, 95 % CI = 1.01-1.64, p = 0.040), and higher numbers of graft rejection episodes (OR = 0.38, 95 % CI = 0.17-0.87, p = 0.023). The following prognostic model for the prediction of PTLD demonstrated good model fit and a large area under the ROC curve (0.823): PTLD probability in % = Exp(y)/(1 + Exp(y)) with y = 0.671 - 1.096 × HLA A2-positive recipient + 0.151 × Tac dosage - 0.805 × number of graft rejection episodes.

CONCLUSIONS

This study suggests prognostic relevance for recipient HLA A2, CMV, and EBV infections or reactivations and strong initial tacrolimus-based immunosuppression. Patients with risk factors may benefit from intensified screening for PTLD.

Post-transplant lymphoproliferative disorder following kidney transplantation: a population-based cohort study

Post-transplant lymphoproliferative disorder (PTLD) incidence is difficult to determine, mainly because both early and other lesions may go unrecognized and unregistered. Few studies have included systematic pathology review to maximize case identification and decide more accurately PTLD frequency after long-term post-transplantation follow-up. A retrospective population-based cohort study including all kidney transplant recipients at two Danish centres (1990-2011; population covered 3.1 million; 2175 transplantations in 1906 patients). Pathology reports were reviewed for all patient biopsies to identify possible PTLDs. Candidate PTLDs underwent histopathological review and classification. Seventy PTLD cases were identified in 2175 transplantations (3.2%). The incidence rate (IR) after first transplantation was 5.4 cases per 1000 patient-years (95% CI: 4.0-7.3). Most PTLDs were monomorphic (58.5%), or early lesions (21.5%). Excluding early lesions and patients <18 years, IR was 3.7 (95% CI: 2.9-5.5). Ten patients with PTLD were retransplanted, 2 developing further PTLDs. Post-transplant patient survival was inferior in patients with PTLD, while death-censored graft survival was not. Using registry data together with extensive pathological review and long follow-up, a rather high incidence of PTLD was found.

Effects of mTOR and calcineurin inhibitors combined therapy in Epstein-Barr virus positive and negative Burkitt lymphoma cells

Post-transplant lymphoproliferative disorder is a severe complication in solid organ transplant recipients, which is highly associated with Epstein-Barr virus infection in pediatric patients and occasionally presents as Burkitt- or Burkitt-like lymphoma. The mammalian target of rapamycin (mTOR) pathway has been described as a possible antitumor target whose inhibition may influence lymphoma development and proliferation after pediatric transplantation. We treated Epstein-Barr virus positive (Raji and Daudi) and negative (Ramos) human Burkitt lymphoma derived cells with mTOR inhibitor everolimus alone and in combination with clinically relevant immunosuppressive calcineurin inhibitors (tacrolimus or cyclosporin A). Cell proliferation, toxicity, and mitochondrial metabolic activity were analyzed. The effect on mTOR Complex 1 downstream targets p70 S6 kinase, eukaryotic initiation factor 4G, and S6 ribosomal protein activation was also investigated. We observed that treatment with everolimus alone significantly decreased Burkitt lymphoma cell proliferation and mitochondrial metabolic activity. Everolimus in combination with cyclosporin A had a stronger suppressive effect in Epstein-Barr virus negative but not in Epstein-Barr virus positive cells. In contrast, tacrolimus completely abolished the everolimus-mediated suppressive effects. Moreover, we showed a significant decrease in activation of mTOR Complex 1 downstream targets after treatment with everolimus that was attenuated when combined with tacrolimus, but not with cyclosporin A. For the first time we showed the competitive effect between everolimus and tacrolimus when used as combination therapy on Burkitt lymphoma derived cells. Thus, according to our in vitro data, the combination of calcineurin inhibitor cyclosporin A with everolimus is preferred to the combination of tacrolimus and everolimus.

Dose-level response rates of mTor inhibition in tuberous sclerosis complex (TSC) related subependymal giant cell astrocytoma (SEGA)

BACKGROUND

Tuberous sclerosis complex (TSC) is an autosomal dominant multisystem disease usually diagnosed in childhood. Subependymal giant cell astrocytomas (SEGA) are benign brain lesions occurring in up to 20% of patients with TSC. Treatment with mTOR inhibitors has been proven effective in inducing SEGA shrinkage, but discontinuation results in re-growth. Evidence suggests that mTOR inhibition seems a disease-modifying treatment for TSC beyond inducing SEGA shrinkage; however concerns remain regarding negative long-term effects.

METHODS

Through this retrospective case series, an attempt was made to determine the minimal mTOR inhibitor dose needed to maintain radiological response of SEGA in six pediatric patients treated at The Hospital for Sick Children since 2007. This study reviews medication doses and blood levels as related to SEGA size on MRIs at 3-month intervals. Blood levels were monitored every 3 months and 2 weeks after dose adjustment. Total dose reduction by 25% was considered after SEGA shrinkage was maintained on two consecutive MRIs.

RESULTS

All patients demonstrated SEGA shrinkage greater than 50% when treated with mTOR inhibition at therapeutic doses (4-5 mg/m(2)). When sirolimus doses were weaned in two patients by 50%, SEGAs regrew by 84% and 32%. In two patients, responses have been maintained with 30% decrease in sirolimus dose. One patient underwent SEGA resection and one remains on therapeutic dose.

CONCLUSIONS

Therapeutic dose of mTOR inhibitor is effective in shrinking TSC-related SEGAs. Doses less than 2.5 mg/m(2) were insufficient to maintain response in this limited series.

Isolated Upper Extremity Posttransplant Lymphoproliferative Disorder in a Child

Posttransplant lymphoproliferative disorder (PTLD) is a well-described complication of solid organ and bone marrow transplants. The most common presentation is intra-abdominal lymphadenopathy or single or multiple intraparenchymal masses involving the liver, spleen, or kidneys. Here we describe the imaging and pathology findings of an unusual case of PTLD appearing as an intramuscular forearm lesion in a pediatric male. The manifestation of PTLD as an isolated upper extremity mass in a pediatric patient has to our knowledge not been described.

Rabbit antithymocyte globulin induction and risk of post-transplant lymphoproliferative disease in adult and pediatric solid organ transplantation: An update

The most modifiable risk factor for post-transplant lymphoproliferative disease (PTLD) is the type and dose of induction and maintenance immunosuppressive therapy. It is challenging to identify the contribution of a single agent such as rabbit antithymocyte globulin (rATG) in the setting of multidrug therapy. Registry analyses can be helpful but are limited by methodological restrictions and inclusion of historical patient cohorts. These are typically from eras when rATG dosing was markedly higher than current dosing (e.g. total dose 14 mg/kg versus 6 mg/kg now), accompanied by higher exposure to maintenance therapies, and often an absence of antiviral prophylaxis. The largest registry analysis to assess rATG specifically found no risk of PTLD after kidney transplantation, but conflicting results have been reported, highlighting the difficulty of interpreting this type of analysis. The relative rarity of PTLD means that individually controlled trials are underpowered to assess its occurrence, but the available data do not suggest an effect of rATG. A pooled analysis of data from studies of rATG induction in kidney and heart transplantation found the incidence of PTLD to be comparable to published reports in the overall transplant population. Data on the effect of rATG dose are inconclusive, but in patients receiving antiviral prophylaxis it does not appear to be influential. Nevertheless, it would seem reasonable to employ the lowest dose of rATG compatible with effective induction, particularly in EBV-seronegative recipients and other high-risk groups such as heart-lung transplant recipients. Overall, the risk of PTLD following rATG induction therapy with modern dosing regimens and under current management conditions appears unlikely to make an important contribution to the risk:benefit balance.

High incidence of Epstein-Barr virus (EBV)-positive Hodgkin lymphoma and Hodgkin lymphoma-like B-cell lymphoproliferations with EBV latency profile 2 in children with interleukin-2-inducible T-cell kinase deficiency

AIMS

Interleukin-2-inducible T-cell kinase (ITK) deficiency is an inherited T-cell deficiency characterized by the development of Epstein-Barr virus (EBV)-associated lymphoproliferations. We aimed to describe the histopathological features of lymphoproliferative processes arising in ITK deficiency, and to compare them with lymphoproliferations in otherwise immunocompromised patients.

METHODS AND RESULTS

We revised the histopathological diagnoses of 12 biopsies of lymphoproliferations from seven ITK-deficient children according to the World Health Organization criteria, and determined the EBV latency types and lytic activity by staining for EBV-encoded small RNA, latent membrane protein 1, EBV nuclear antigen 2, and ZEBRA. We found polymorphic and borderline polymorphic to monomorphic B-cell lymphoproliferations with variable contents in large cells (five cases), a Hodgkin-like B-cell proliferation (one case), and classic mixed-cellularity Hodgkin lymphoma (six cases). All cases (12/12) were EBV-positive. The Hodgkin lymphoma-like and Hodgkin lymphoma, and all but one polymorphic B-cell lymphoproliferation, showed EBV latency type 2, as observed in classic EBV-positive Hodgkin lymphoma.

CONCLUSIONS

The 100% EBV association, the high percentage of EBV-positive classic Hodgkin lymphoma and Hodgkin-like B-cell proliferations and the predominance of EBV latency type 2 even in polymorphic lesions are the main features of lymphoproliferations in patients with ITK deficiency, and suggest a unique pathomechanism of lymphomagenesis in this T-cell immunodeficiency.

Successful treatment of systemic and central nervous system post-transplant lymphoproliferative disorder without the use of high-dose methotrexate or radiation

Post-transplant lymphoproliferative disorder (PTLD) describes a spectrum of conditions with highest incidence in the first year post-solid organ transplant in pediatric patients. Central nervous system (CNS) involvement with PTLD carries high mortality risk with no consensus on optimal therapeutic regimen. We present the case of a 7-year old heart transplant patient diagnosed with widespread monomorphic, CD20+, Epstein-Barr virus-positive PTLD, including CNS involvement. In addition to immunosuppression reduction and rituximab, she was treated with multiagent systemic and intrathecal chemotherapy. She achieved a prompt and complete clinical and radiologic remission, which has been sustained for over 46 months since diagnosis.

Malignancies after pediatric kidney transplantation: more than PTLD?

Post-transplant lymphoproliferative disease (PTLD) is the most frequent malignant complication of transplantation in childhood. Even with modern post-transplant immunosuppressive strategies, 1-2% of all kidney transplant recipients will develop PTLD within the first 5 years after transplantation, and the risk remains high even thereafter as long as immunosuppression is required. In addition to PTLD, adult kidney transplant recipients have an increased incidence of other immunosuppression-related malignancies, such as non-melanoma skin cancer or Kaposi's sarcoma. It is foreseeable that pediatric transplant recipients will face similar complications during their adult life. Not only immunosuppression but also other risk factors have been identified for some of these malignancies. Strategies addressing these risk factors during childhood may contribute to life-long cancer prevention. Furthermore, early recognition and regular screening may facilitate early diagnosis and treatment, thereby reducing transplant-related morbidity. In this review we focus on malignant complications after renal transplantation and discuss known risk factors. We also review current screening strategies for malignancies during post-transplant follow-up.

Pattern analysis of Epstein-Barr virus viremia and its significance in the evaluation of organ transplant patients suspected of having posttransplant lymphoproliferative disorders

OBJECTIVES

To explore posttransplant lymphoproliferative disorder (PTLD) cases associated with Epstein-Barr virus (EBV).

METHODS

We retrospectively reviewed the EBV DNA quantitation data of 9,779 blood samples from 740 transplant patients and their associations with PTLD.

RESULTS

EBV viremia occurred more frequently in patients with PTLD (85.4%) in comparison with patients without PTLD (38.3%; P < .0001). Patients with PTLD demonstrated significantly higher first positive results, higher peak levels, and a higher rate of increase in EBV viral load compared with patients without PTLD (P = .002, P < .0001, and P < .0001, respectively). However, in the multivariate analysis, only the peak level was associated with the development of PTLD. In particular, within hematopoietic stem cell recipients, the peak level able to diagnose PTLD was an area under the receiver operating characteristic curve of 0.806.

CONCLUSIONS

We believe that pattern analysis of EBV DNA quantitation results could lead to the early diagnosis and timely treatment of PTLD.

Malignancies: pre and post transplantation strategies

The overall incidence of cancer is increased 2-3 fold in solid organ transplant recipients compared to the general population. The increase in risk is not uniform for all malignancies, in all ages or in all regions of the world. Several cancers are greatly increased, many are increased 2-4 fold and others do not appear to be increased at all. The pattern of increase is similar to patients with acquired immunodeficiency syndrome and those cancers most increased are associated with viral infections. These observations support the concept that much of the increased risk is from immunosuppression. Nonetheless there are differences between specific organ groups that deserve further examination. Those with advanced organ failure are also at increased risk for certain malignancies, which suggest either organ damage per se may pre-dispose to cancers or there are exposures to carcinogens in common. The purpose of this review to examine cancer incidence and mortality in solid organ transplantation and the role of pre transplant screening and post-transplant surveillance to reduce the burden of disease and improve patient outcomes. This review will focus on cancers that are common, associated with significant case fatality rates and have potential screening strategies to reduce burden of disease.

Spectrum of Epstein-Barr virus-associated diseases in recipients of allogeneic hematopoietic stem cell transplantation

BACKGROUND

Epstein-Barr virus (EBV) infection may result in a spectrum of diseases in recipients of transplant. The aim of this study is to investigate the incidence, clinical characteristics, and prognosis of the spectrum of EBV-associated diseases in recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT).

METHODS

A total of 263 recipients undergoing allo-HSCT were prospectively enrolled. The blood EBV-DNA loads were regularly monitored by quantitative real-time polymerase chain reaction.

RESULTS

The 3-year cumulative incidence of total EBV-associated diseases, posttransplantation lymphoproliferative diseases (PTLD), EBV fever, and EBV end-organ diseases (pneumonia, encephalitis/myelitis, and hepatitis) were 15.6%±2.5%, 9.9%±2.0%, 3.3%±1.3%, and 3.3%±1.2% (2.2%±1.0%, 1.6%±0.8%, and 0.9%±0.6%), respectively. Fever was the most common symptom of EBV-associated diseases. Patients with PTLD had better response rate to rituximab-based treatments compared with those with EBV end-organ diseases (including PTLD accompanied by EBV end-organ diseases) (P=0.014). The 3-year overall survival was 37.3%±13.7%, 100.0%, and 0.0%±0.0% in patients with PTLD, EBV fever, and EBV end-organ diseases (P=0.001).

CONCLUSIONS

EBV-associated diseases other than PTLD are not rare in the recipients of allo-HSCT. The clinical manifestations of EBV end-organ diseases are similar to PTLD. EBV end-organ diseases had poorer response to rituximab-based therapy compared with PTLD.

Posttransplant lymphoproliferative disease after pediatric solid organ transplantation

Patients after solid organ transplantation (SOT) carry a substantially increased risk to develop malignant lymphomas. This is in part due to the immunosuppression required to maintain the function of the organ graft. Depending on the transplanted organ, up to 15% of pediatric transplant recipients acquire posttransplant lymphoproliferative disease (PTLD), and eventually 20% of those succumb to the disease. Early diagnosis of PTLD is often hampered by the unspecific symptoms and the difficult differential diagnosis, which includes atypical infections as well as graft rejection. Treatment of PTLD is limited by the high vulnerability towards antineoplastic chemotherapy in transplanted children. However, new treatment strategies and especially the introduction of the monoclonal anti-CD20 antibody rituximab have dramatically improved outcomes of PTLD. This review discusses risk factors for the development of PTLD in children, summarizes current approaches to therapy, and gives an outlook on developing new treatment modalities like targeted therapy with virus-specific T cells. Finally, monitoring strategies are evaluated.

Post-transplant lymphoproliferative disease in pediatric solid organ transplant recipients

Post-transplant lymphoproliferative disease (PTLD) in solid organ transplant (SOT) recipients has become one of the most common forms of lymphoproliferation in childhood and is a serious complication of SOT. More than 90% of cases are of B-cell origin, Epstein Barr virus (EBV) positive and are mostly occurring in the early post-transplant period. Pathologically and clinically it is a heterogenous disease ranging from being responsive to reduced immunosuppression without further intervention to rapidly progressive fulminant PTLD requiring prompt initiation of therapy. Prognosis overall is favorable. Current treatment strategies as well new promising targeted immune-based therapies such as rituximab and EBV-specific cytotoxic T-lymphocytes are being discussed.

Posttransplant lymphoproliferative disorder in pediatric patients

Transplantation of solid organs and hematopoietic stem cells is accompanied by profound disturbance of immune function mediated by immunosuppressive drugs or delayed immune reconstitution. Disturbed T cell control of Epstein-Barr virus (EBV)-infected B cells leads to posttransplant lymphoproliferative disorder (PTLD) in up to 10% of patients. Children are at a higher risk because they are more often EBV-naïve before transplantation. Patients with PTLD often present with unspecific symptoms (pain and organ/graft dysfunction). Depending on the onset of PTLD, manifestations vary between mainly nodal (late PTLD) and extranodal sites (early PTLD). Histology, immunohistology, EBER in situ hybridization and molecular pathology are required for diagnosis and subclassification of PTLD. The three major types are early lesions (resembling reactive proliferations in immunocompetent patients), polymorphic PTLD (proliferation of B and T cells with effacement of histoarchitecture) and monomorphic PTLD (presenting as malignant lymphomas, mainly high-grade B cell lymphomas). In a subfraction of cases, including monomorphic PTLD, reduction of immunosuppressive medication alone is sufficient to induce remission. Surgical debulking of tumor mass and anti-CD20-antibody treatment with or without chemotherapy (usually at lower dosages than in immunocompetent patients) constitute the basis of additional therapy.

De novo malignancies after adult-to-adult living-donor liver transplantation with a malignancy surveillance program: comparison with a Japanese population-based study

BACKGROUND

Organ transplant recipients have an increased incidence of malignancy. Race differences in a variety of malignancies are observed among the general population, but de novo malignancies after adult-to-adult living-donor liver transplantation (LDLT) have not been compared with those from a Japanese population-based study.

METHODS

The subjects were 360 adult LDLT recipients who survived more than 1 year after transplantation. An annual medical checkup and screening examinations were performed as follows: abdominal computed tomography or magnetic resonance imaging, upper gastrointestinal endoscopy, and total colonoscopy and immunochemical fecal occult blood test every 1 to 2 years. Complete blood count, liver function tests, and several tumor markers were checked every 1 to 3 months after LDLT.

RESULTS

Mean follow-up period was 7.5±3.4 years. During the follow-up period, 27 de novo malignancies were diagnosed in 26 recipients. Colorectal cancer was the most commonly detected malignancy. The overall mortality of the recipients with de novo malignancies was similar to the findings of the Japanese general population-based study (standardized mortality ratio=0.9). Overall, the incidence of cancer was significantly higher in transplant recipients than in the Japanese general population (standardized incidence ratio=1.8). The 5-year estimated survival rate of recipients with de novo malignancies was 81% and those of recipients without malignancies was 93% (P<0.0001).

CONCLUSIONS

Colorectal malignancies predominated in Japanese liver transplant recipients. Although de novo malignancies correlated with a poor prognosis, the standardized mortality ratio was 0.9 compared with that of subjects of a Japanese population-based study.