Epstein-Barr virus-associated posttransplant lymphoproliferative disorders: new insights in pathogenesis, classification and treatment

Treatment of Epstein-Barr Virus infection in immunocompromised patients

Epstein-Barr Virus (EBV), is a ubiquitous γ-Herpesvirus that infects over 95% of the human population and can establish a life-long infection without causing any clinical symptoms in healthy individuals by residing in memory B-cells. Primary infection occurs in childhood and is mostly asymptomatic, however in some young adults it can result in infectious mononucleosis (IM). In immunocompromised individuals however, EBV infection has been associated with many different malignancies. Since EBV can infect both epithelial and B-cells and very rarely NK cells and T-cells, it is associated with both epithelial cancers like nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC), with lymphomas including Burkitt Lymphoma (BL) or Post-transplant Lymphoproliferative Disorder (PTLD) and rarely with NK/T-cell lymphomas. Currently there are no approved antivirals active in PTLD nor in any other malignancy. Moreover, lytic phase disease almost never requires antiviral treatment. Although many novel therapies against EBV have been described, the management and/or prevention of EBV primary infections or reactivations remains difficult. In this review, we discuss EBV infection, therapies targeting EBV in both lytic and latent state with novel therapeutics developed that show anti-EBV activity as well as EBV-associated malignancies both, epithelial and lymphoproliferative malignancies and emerging therapies targeting the EBV-infected cells.

Diverse and reprogrammable mechanisms of malignant cell transformation in lymphocytes: pathogenetic insights and translational implications

While normal B- and T-lymphocytes require antigenic ligands to become activated via their B- and T-cell receptors (BCR and TCR, respectively), B- and T-cell lymphomas show the broad spectrum of cell activation mechanisms regarding their dependence on BCR or TCR signaling, including loss of such dependence. These mechanisms are generally better understood and characterized for B-cell than for T-cell lymphomas. While some lymphomas, particularly the indolent, low-grade ones remain antigen-driven, other retain dependence on activation of their antigen receptors seemingly in an antigen-independent manner with activating mutations of the receptors playing a role. A large group of lymphomas, however, displays complete antigen receptor independence, which can develop gradually, in a stepwise manner or abruptly, through involvement of powerful oncogenes. Whereas some of the lymphomas undergo activating mutations of genes encoding proteins involved in signaling cascades downstream of the antigen-receptors, others employ activation mechanisms capable of substituting for these BCR- or TCR-dependent signaling pathways, including reliance on signaling pathways physiologically activated by cytokines. Finally, lymphomas can develop cell-lineage infidelity and in the extreme cases drastically rewire their cell activation mechanisms and engage receptors and signaling pathways physiologically active in hematopoietic stem cells or non-lymphoid cells. Such profound reprograming may involve partial cell dedifferentiation or transdifferentiation towards histocytes, dendritic, or mesodermal cells with various degree of cell maturation along these lineages. In this review, we elaborate on these diverse pathogenic mechanisms underlying cell plasticity and signaling reprogramming as well as discuss the related diagnostic and therapeutic implications and challenges.

Global research productivity of post-transplant lymphoproliferative disorder: a bibliometric study

Background

Post-transplant lymphoproliferative diseases (PTLD) are a heterogeneous collection of neoplasms that occur after solid organ transplants (SOT). In the past 20 years, there has been a rise in PTLD research. This study aims to investigate the global research output and interest regarding PTLD using a bibliometric approach.

Material and methods

On 28 November 2022, the Web of Science Core Collection documents on PTLD published between 2000 and 2022 were collected and analyzed using bibliometric techniques. The VOSviewer application was utilized to visualize the annual number of publications, authors, organizations, countries, published journals, citations, and most occurring keywords.

Results

A total of 2814 documents were retrieved, and a screening process included 1809 documents. The total number of citations was 45 239, and the average number per item was 25. Most articles (n = 747) and citations (n = 25 740) were produced in the United States. Based on citations, most of the top 10 institutions that contributed were in the United States of America. The University of Pittsburgh topped the list with 2700 citations and 64 articles. The vast majority of articles were published in Pediatric Transplantation (n = 147), Transplantation (n = 124), and the American Journal of Transplantation (n = 98). Transplantation has received the most citations, 6499, followed by the American Journal of Transplantation with 5958 citations and Blood with 4107 citations.

Conclusion

With ongoing debates over optimal classification, Epstein-Bar virus involvement, and treatment, this topic has received significant interest from researchers in recent years. Our results can be used as a guide for future research in the field and as a framework for a more in-depth look at the scientific progress of PTLD.

Tabelecleucel for allogeneic haematopoietic stem-cell or solid organ transplant recipients with Epstein-Barr virus-positive post-transplant lymphoproliferative disease after failure of rituximab or rituximab and chemotherapy (ALLELE): a phase 3, multicentre, open-label trial

BACKGROUND

Survival in Epstein-Barr virus (EBV)-positive post-transplant lymphoproliferative disease following haematopoietic stem-cell transplant (HSCT) or solid organ transplant (SOT) is poor after failure of initial therapy, indicating an urgent need for therapies for this ultra-rare disease. With recent EU marketing authorisation, tabelecleucel is the first off-the-shelf, allogeneic, EBV-specific T-cell immunotherapy to receive approval for treatment of relapsed or refractory EBV-positive post-transplant lymphoproliferative disease. We aimed to determine the clinical benefit of tabelecleucel in patients with relapsed or refractory EBV-positive post-transplant lymphoproliferative disease following HSCT or SOT.

METHODS

In this global, multicentre, open-label, phase 3 trial, eligible patients (of any age) had biopsy-proven EBV-positive post-transplant lymphoproliferative disease, disease that was relapsed or refractory to rituximab after HSCT and rituximab with or without chemotherapy after SOT, and partially HLA-matched and appropriately HLA-restricted tabelecleucel available. Patients received tabelecleucel administered intravenously at 2 × 106 cells per kg on days 1, 8, and 15 in 35-day cycles and are assessed for up to 5 years for survival post-treatment initiation. The primary endpoint was objective response rate. All patients who received at least one dose of tabelecleucel were included in safety and efficacy analyses. This trial is registered with ClinicalTrials.gov, NCT03394365, and is ongoing.

FINDINGS

From June 27, 2018, to Nov 5, 2021, 63 patients were enrolled, of whom 43 (24 [56%] male and 19 [44%] female) were included, 14 had prior HSCT, 29 had SOT. Seven (50%, 95% CI 23-77) of 14 participants in the HSCT group and 15 (52%, 33-71) of 29 participants in the SOT group had an objective response, with a median follow-up of 14·1 months (IQR 5·7-23·9) and 6·0 months (1·8-18·4), respectively. The most common grade 3 or 4 treatment-emergent adverse events were disease progression (in four [29%] of 14 in HSCT and eight [28%] of 29 in SOT) and decreased neutrophil count (in four [29%] of 14 in HSCT and four [14%] of 29 in SOT). Treatment-emergent serious adverse events were reported in 23 (53%) of 43 patients and fatal treatment-emergent adverse events in five (12%); no fatal treatment-emergent adverse event was treatment-related. There were no reports of tumour flare reaction, cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, transmission of infectious diseases, marrow rejection, or infusion reactions. No events of graft-versus-host disease or SOT rejection were reported as related to tabelecleucel.

INTERPRETATION

Tabelecleucel provides clinical benefit in patients with relapsed or refractory EBV-positive post-transplant lymphoproliferative disease, for whom there are no other approved therapies, without evidence of safety concerns seen with other adoptive T-cell therapies. These data represent a potentially transformative and accessible treatment advance for patients with relapsed or refractory disease with few treatment options.

FUNDING

Atara Biotherapeutics.

Tabelecleucel: First Approval

Tabelecleucel (Ebvallo^TM) is an allogeneic Epstein-Barr virus (EBV)-specific T-cell immunotherapy that targets and eliminates EBV positive (EBV⁺) cells in a human leukocyte antigen (HLA) restricted manner. Tabelecleucel has been developed by Atara Biotherapeutics under a license from Memorial Sloan-Kettering Cancer Center (MSKCC) for the treatment of lymphoproliferative disorders (LPDs), including rituximab relapsed/refractory EBV⁺ post-transplant lymphoproliferative disease (PTLD). Tabelecleucel was granted marketing authorization under 'exceptional circumstances' on 16 December 2022 as monotherapy for the treatment of adult and paediatric patients 2 years of age and older with relapsed or refractory EBV⁺ PTLD who have received at least one prior therapy. For solid organ transplant patients, prior therapy includes chemotherapy unless chemotherapy is inappropriate. This article summarizes the milestones in the development of tabelecleucel leading to this first approval for EBV⁺ PTLD.