EBV-positive DLBCL frequently harbors somatic mutations associated with clonal hematopoiesis of indeterminate potential

EBV-positive diffuse large B-cell lymphoma, not otherwise specified: 2024 update on the diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Epstein Barr virus-positive (EBV+) diffuse large B-cell lymphoma (DLBCL), not otherwise specified (NOS) is an aggressive B-cell lymphoma associated with EBV infection included in the WHO classification of lymphoid neoplasms since 2016. Although historically associated to poor prognosis, outcomes seem to have improved in the era of chemoimmunotherapy.

DIAGNOSIS

The diagnosis is established through meticulous pathological evaluation. Detection of EBV-encoded RNA (EBER) is the standard diagnostic method. The ICC 2022 specifies EBV+ DLBCL, NOS as occurring when >80% of malignant cells express EBER, whereas the WHO-HAEM5 emphasizes that the majority of tumor cells should be EBER positive without setting a defined threshold. The differential diagnosis includes plasmablastic lymphoma, DLBCL associated with chronic inflammation, primary effusion lymphoma, among others.

RISK-STRATIFICATION

The International Prognostic Index (IPI) and the Oyama score can be used for risk-stratification. The Oyama score includes age >70 years and presence of B symptoms. The expression of CD30 and PD-1/PD-L1 are emerging as potential adverse but targetable biomarkers.

MANAGEMENT

Patients with EBV+ DLBCL, NOS, should be staged and managed following similar guidelines than patients with EBV-negative DLBCL. EBV+ DLBCL, NOS, however, might have a worse prognosis than EBV-negative DLBCL in the era of chemoimmunotherapy. Therefore, inclusion of patients in clinical trials when available is recommended. There is an opportunity to study and develop targeted therapy in the management of patients with EBV+ DLBCL, NOS.

Risk of Second Tumors and T-Cell Lymphoma after CAR T-Cell Therapy

BACKGROUND

The risk of second tumors after chimeric antigen receptor (CAR) T-cell therapy, especially the risk of T-cell neoplasms related to viral vector integration, is an emerging concern.

METHODS

We reviewed our clinical experience with adoptive cellular CAR T-cell therapy at our institution since 2016 and ascertained the occurrence of second tumors. In one case of secondary T-cell lymphoma, a broad array of molecular, genetic, and cellular techniques were used to interrogate the tumor, the CAR T cells, and the normal hematopoietic cells in the patient.

RESULTS

A total of 724 patients who had received T-cell therapies at our center were included in the study. A lethal T-cell lymphoma was identified in a patient who had received axicabtagene ciloleucel therapy for diffuse large B-cell lymphoma, and both lymphomas were deeply profiled. Each lymphoma had molecularly distinct immunophenotypes and genomic profiles, but both were positive for Epstein-Barr virus and were associated with DNMT3A and TET2 mutant clonal hematopoiesis. No evidence of oncogenic retroviral integration was found with the use of multiple techniques.

CONCLUSIONS

Our results highlight the rarity of second tumors and provide a framework for defining clonal relationships and viral vector monitoring. (Funded by the National Cancer Institute and others.).

Targeted mutational profiling of Epstein Barr virus-positive mucocutaneous ulcer: Implications for differential diagnosis with EBV-positive diffuse large B-cell lymphoma

Epstein Barr Virus-positive mucocutaneous ulcer (EBVMCU) can be difficult to distinguish from EBV-positive diffuse large B cell lymphoma (DLBCL). We used targeted next-generation sequencing (NGS) to explore genetic alterations in EBVMCU to aid in this diagnostic challenge. Ten cases of EBVMCU were evaluated by a targeted NGS panel of 164 genes. Targeted NGS identified 18 variants in 15 genes in eight cases of EBVMCU. Loss of function TET2 variants were most frequently identified (3 of 10 cases, 30 %). One TET2 variant occurred at low variant allele frequency (VAF) of 3 %, which may be suggestive of clonal hematopoiesis of indeterminate potential. One case harbored a loss of function DNMT3A variant at low VAF. Two cases demonstrated missense variants in the IRF8 gene. Both variants occurred at a VAF close to 50 % and with an estimated high burden of disease (75 %). Two cases of mucosal gastrointestinal involvement had no reportable variants. Mutational profiling of EBVMCU identified TET2 loss of function variants at an elevated frequency in our cohort; however, the findings are not specific and its clinical significance cannot be completely elucidated. Further studies are needed to confirm the findings in an independent and larger cohort of EBVMCU, to determine the cell of origin of the variants, and to further assess their significance in the pathogenesis of this disorder.

Update: The molecular spectrum of virus-associated high-grade B-cell non-Hodgkin lymphomas

The vast spectrum of aggressive B-cell non-Hodgkin neoplasms (B-NHL) encompasses several infrequent entities occurring in association with viral infections, posing diagnostic challenges for practitioners. In the emerging era of precision oncology, the molecular characterization of malignancies has acquired paramount significance. The pathophysiological comprehension of specific entities and the identification of targeted therapeutic options have seen rapid development. However, owing to their rarity, not all entities have undergone exhaustive molecular characterization. Considerable heterogeneity exists in the extant body of work, both in terms of employed methodologies and the scale of cases studied. Presently, therapeutic strategies are predominantly derived from observations in diffuse large B-cell lymphoma (DLBCL), the most prevalent subset of aggressive B-NHL. Ongoing investigations into the molecular profiles of these uncommon virus-associated entities are progressively facilitating a clearer distinction from DLBCL, ultimately paving the way towards individualized therapeutic approaches. This review consolidates the current molecular insights into aggressive and virus-associated B-NHL, taking into consideration the recently updated 5th edition of the WHO classification of hematolymphoid tumors (WHO-5HAEM) and the International Consensus Classification (ICC). Additionally, potential therapeutically targetable susceptibilities are highlighted, offering a comprehensive overview of the present scientific landscape in the field.

The Immunology of DLBCL

Diffuse large B-cell lymphoma (DLBCL) is an aggressive malignancy and is the most common type of malignant lymphoid neoplasm. While some DLBCLs exhibit strong cell-autonomous survival and proliferation activity, others depend on interactions with non-malignant cells for their survival and proliferation. Recent next-generation sequencing studies have linked these interactions with the molecular classification of DLBCL. For example, germinal center B-cell-like DLBCL tends to show strong associations with follicular T cells and epigenetic regulation of immune recognition molecules, whereas activated B-cell-like DLBCL shows frequent genetic aberrations affecting the class I major histocompatibility complex. Single-cell technologies have also provided detailed information about cell-cell interactions and the cell composition of the microenvironment of DLBCL. Aging-related immunological deterioration, i.e., immunosenescence, also plays an important role in DLBCL pathogenesis, especially in Epstein-Barr virus-positive DLBCL. Moreover, DLBCL in "immune-privileged sites"-where multiple immune-modulating mechanisms exist-shows unique biological features, including frequent down-regulation of immune recognition molecules and an immune-tolerogenic tumor microenvironment. These advances in understanding the immunology of DLBCL may contribute to the development of novel therapies targeting immune systems.