Multicenter study of pediatric Epstein-Barr virus-negative monomorphic post solid organ transplant lymphoproliferative disorders

Incidence and Management of Posttransplantation Lymphoproliferative Disorder After Pediatric Solid Organ Transplantation: The Norwegian Experience

BACKGROUND

Posttransplant lymphoproliferative disorder (PTLD) is a complication of solid organ transplantation (SOT) due to immunosuppression. In 2023, a pediatric PTLD register was established in Norway because of a perceived increase in the incidence of pediatric PTLD. This study aimed to analyze population-based data on the incidence and management of pediatric PTLD after SOT using the pediatric PTLD registry in Norway.

METHODS

This retrospective quality assurance study collected the data of pediatric patients with PTLD after SOT in Norway from January 1, 1995, to December 31, 2023. For comparison and calculation of incidence rates, SOT patients without PTLD required a minimum of 1 year posttransplant follow-up to be included.

RESULTS

A total of 457 patients underwent SOT (57% males) and 22 (4.8%) developed PTLD (73% males). The median age at transplant in the SOT and PTLD groups were 9.5 (interquartile range, 2.4-14.5) and 4.3 (1.1-12.5) years, respectively. Twenty patients with PTLD (91%) were Epstein-Barr virus naive at the time of transplantation. Eighteen (82%) and four (18%) patients developed early and late PTLD, respectively. Ten patients had monomorphic PTLD (45%). All patients received a reduction in immunosuppression, 15 received rituximab, and six required chemotherapy. Six patients (27%) died after PTLD, five of whom had active PTLD disease at the time of death. None of the patients experienced graft loss.

CONCLUSIONS

Our findings regarding the incidence, EBV status, sex, and age at transplantation align with those of previous studies.

Dedicated diagnostic approaches for mature B-cell non-Hodgkin lymphomas occurring in children, adolescents, and young adults

Non-Hodgkin lymphoma (NHL) represents the fourth most common malignant disease among children and adolescents. Current disease classifications, including the most recent World Health Organization (WHO) classification and the International Consensus Classification (ICC), rely on a combination of clinical, epidemiological, histologic, immunophenotypic, and molecular data to define discrete clinicopathologic entities. There is growing evidence that children, adolescents, and young adults (CAYA) with B-cell NHL display unique clinical and epidemiologic characteristics. This may be explained by distinct age-related developmental plasticity, immune and haematopoietic repertoires, environmental exposures and social determinants of health, and germline or acquired genetic and molecular features, including those associated with inborn errors of immunity (IEI). Here, we discuss the unique clinical and biological characteristics of several distinct paediatric B-cell NHL types to indicate a path forward in classification of these CAYA NHL to optimally support multidisciplinary patient care and personalized treatment. We propose a potential "arising in CAYA" classification qualifier to denote the distinct clinicopathologic characteristics of B-cell NHLs that, otherwise, histologically and immunophenotypically resemble those arising in middle-aged and older adults. We also discuss how haemopathology diagnoses are evolving to incorporate the most current scientific knowledge into future classification systems of CAYA B-cell NHL.

Multi-modal analysis reveals tumor and immune features distinguishing EBV-positive and EBV-negative post-transplant lymphoproliferative disorders

The oncogenic Epstein-Barr virus (EBV) can drive tumorigenesis with disrupted host immunity, causing malignancies including post-transplant lymphoproliferative disorders (PTLDs). PTLD can also arise in the absence of EBV, but the biological differences underlying EBV(+) and EBV(-) B cell PTLD and the associated host-EBV-tumor interactions remain poorly understood. Here, we reveal the core differences between EBV(+) and EBV(-) PTLD, characterized by increased expression of genes related to immune processes or DNA interactions, respectively, and the augmented ability of EBV(+) PTLD B cells to modulate the tumor microenvironment through elaboration of monocyte-attracting cytokines/chemokines. We create a reference resource of proteins distinguishing EBV(+) B lymphoma cells from EBV(-) B lymphoma including the immunomodulatory molecules CD300a and CD24, respectively. Moreover, we show that CD300a is essential for maximal survival of EBV(+) PTLD B lymphoma cells. Our comprehensive multi-modal analyses uncover the biological underpinnings of PTLD and offer opportunities for precision therapies.

EBV and post-transplant lymphoproliferative disorder: a complex relationship

Post-transplant lymphoproliferative disorders (PTLD) are a heterogeneous category of disease entities occurring in the context of iatrogenic immune suppression. Epstein-Barr virus (EBV)-driven B-cell lymphoproliferation represents the prototype of quintessential PTLD, which includes a range of histologies named nondestructive, polymorphic, and monomorphic EBV+ diffuse large B-cell lymphoma (DLBCL) PTLD. While EBV is associated with the majority of PTLD cases, other drivers of lymphoid neoplasia and lymphoma transformation can occur-with or without EBV as a codriver-thus underlining its vast heterogeneity. In this review, we discuss the evolution in contemporary PTLD nomenclature and its emphasis on more precise subcategorization, with a focus on solid organ transplants in children, adolescents, and young adults. We highlight the fact that patients with quintessential EBV-associated PTLD-including those with monomorphic DLBCL-can be cured with low-intensity therapeutic approaches such as reduction in immune suppression, surgical resection, rituximab monotherapy, or rituximab plus low-dose chemotherapy. There is, though, a subset of patients (approximately 30%-40%) with quintessential PTLD that remains refractory to lower-intensity approaches, for whom intensive, lymphoma-specific chemotherapy regimens are required. Other forms of monomorphic PTLD, which are as diverse as the spectrum of defined lymphoma entities that also occur in immunocompetent patients, are rarely cured with lower-intensity therapies and appear to be better categorized as posttransplant lymphomas. These distinct scenarios represent the variations in lymphoid pathology that make up a conceptual framework for PTLD consisting of lymphoid hyperplasia, neoplasia, and malignancy. This framework serves as the basis to inform risk stratification and determination of evidence-based treatment strategies.

Clinicopathologic Spectrum of Pediatric Posttransplant Lymphoproliferative Diseases Following Solid Organ Transplant

CONTEXT.—

Posttransplant lymphoproliferative disorder (PTLD) remains a significant complication in pediatric patients undergoing solid organ transplant (SOT). The majority involve Epstein-Barr virus (EBV)-driven CD20+ B-cell proliferations, which respond to reduction of immunosuppression and anti-CD20-directed immunotherapy. Owing to the low overall incidence, prospective studies of pediatric PTLD are scarce, leading to a lack of comprehensive understanding of this disorder in pediatric populations. This review aims to bridge this knowledge gap by providing a comprehensive analysis of the clinical, morphologic, and molecular genetic features of PTLD in children, adolescents, and young adults after SOT.

OBJECTIVE.—

To examine the clinical features, pathogenesis, and classification of pediatric PTLDs after SOT.

DATA SOURCES.—

Personal experiences and published works in PubMed.

CONCLUSIONS.—

PTLD includes a broad and heterogeneous spectrum of disorders, ranging from nonmalignant lymphoproliferations to lymphomas. While most pediatric PTLDs are EBV+, an increasing number of EBV- PTLDs have been recognized. The pathologic classification of PTLDs has evolved in recent decades, reflecting advancements in understanding the underlying pathobiology. Nevertheless, there remains a great need for further research to elucidate the biology, identify patients at higher risk for aggressive disease, and establish optimal treatment strategies for relapsed/refractory disease.

Management of paediatric monomorphic post-transplant lymphoproliferative disorders with low-intensity treatment: A multicentre international experience

BACKGROUND

Monomorphic post-transplant lymphoproliferative disorder (mPTLD) is a major cause of morbidity/mortality following solid organ transplant (SOT), with infection, mPTLD progression and organ rejection presenting equal risks. Balancing these risks is challenging, and the intensity of therapy required by individual patients is not defined. Although an increasing body of evidence supports the use of a stepwise escalation of therapy through reduction in immunosuppression (RIS) to rituximab monotherapy and low-dose chemo-immunotherapy, many centres still use B-cell non-Hodgkin lymphoma (B-NHL) protocols, especially when managing Burkitt/Burkitt-like (BL) PTLD. This study sought to define outcomes for children managed in the UK or Spanish centres using low-intensity first-line treatments.

PROCEDURE

Retrospective data were anonymously collected on patients younger than 18 years of age, with post-SOT mPTLD diagnosed between 2000 and 2020. Only patients given low-intensity treatment at initial diagnosis were included.

RESULTS

Fifty-six patients were identified. Age range was 0.9-18 years (median 10.7). Most (62.5%) had early-onset PTLD. Haematopathological analysis showed 75% were diffuse large B-cell like, 14.3% were BL and nine of 33 (27%) harboured a MYC-rearrangement. Stage III-IV disease was present in 78.6%. All but one had RIS, 26 received rituximab monotherapy and 24 low-dose chemo-immunotherapy, mostly R-COP. Intensified B-NHL chemotherapy was required in 10/56 (17.9%). There were a total of 13 deaths in this cohort, three related to PTLD progression. The 1-year overall survival (OS), event-free survival (EFS) and progression-free survival (PFS) were 92.8%, 78.6% and 80.2%, respectively.

CONCLUSIONS

R-COP provides an effective low-dose chemotherapy option. Escalation to more intensive therapies in the minority of inadequately controlled patients is an effective strategy.

Pediatric Kidney Transplantation: Cancer and Cancer Risk

Children with end-stage kidney disease (ESKD) face a lifetime of complex medical care, alternating between maintenance chronic dialysis and kidney transplantation. Kidney transplantation has emerged as the optimal treatment of ESKD for children and provides important quality of life and survival advantages. Although transplantation is the preferred therapy, lifetime exposure to immunosuppression among children with ESKD is associated with increased morbidity, including an increased risk of cancer. Following pediatric kidney transplantation, cancer events occurring during childhood or young adulthood can be divided into two broad categories: post-transplant lymphoproliferative disorders and non-lymphoproliferative solid tumors. This review provides an overview of cancer incidence, types, outcomes, and preventive strategies in this population.

Update on Epidemiology and Outcomes of Infection in Pediatric Organ Transplant Recipients

Pediatric solid organ transplant (SOT) recipients are at risk for infection following transplantation. Data from adult SOT recipients are often used to guide prevention and treatment of infections associated with organ transplantation in children. This article highlights key recent pediatric SOT-specific publications for an array of infectious complications of organ transplantation. Attention is given to areas of need for future study.