Gene expression analysis of angioimmunoblastic lymphoma indicates derivation from T follicular helper cells and vascular endothelial growth factor deregulation

Fifth Edition of the World Health Organization Classification of Tumors of the Hematopoietic and Lymphoid Tissues: Mature T-Cell, NK-Cell, and Stroma-Derived Neoplasms of Lymphoid Tissues

This review focuses on mature T cells, natural killer (NK) cells, and stroma-derived neoplasms in the fifth edition of the World Health Organization classification of hematolymphoid tumors, including changes from the revised fourth edition. Overall, information has expanded, primarily due to advancements in genomic understanding. The updated classification adopts a hierarchical format. The updated classification relies on a multidisciplinary approach, incorporating insights from a diverse group of pathologists, clinicians, and geneticists. Indolent NK-cell lymphoproliferative disorder of the gastrointestinal tract, Epstein-Barr virus-positive nodal T- and NK-cell lymphoma, and several stroma-derived neoplasms of lymphoid tissues have been newly introduced or included. The review also provides guidance on how the fifth edition of the World Health Organization classification of hematolymphoid tumors can be applied in routine clinical practice.

Single-cell landscape reveals the immune heterogeneity of bone marrow involvement in peripheral T-cell lymphoma

The prognosis of patients with peripheral T-cell lymphoma (PTCL) depends on bone marrow involvement (BMI). The bone marrow (BM) tumor microenvironment in PTCL remains unclear. We performed single-cell RNA sequencing (scRNA-seq) on 11 fresh BM samples from patients with BMI to reveal the associations of immune landscape and genetic variations with the prognosis of PTCL patients. Compared with PTCL not otherwise specified (NOS), angioimmunoblastic T-cell lymphoma (AITL) had a higher number of T cells, lower number of lymphocytes, and greater inflammation. Immune heterogeneity in AITL is associated with prognosis. In particular, specific T-cell receptor (TCR) T cells are enriched in patients with good response to anti-CD30 therapy. We observed RhoA mutation-associated neoantigens. Chidamide-treated patients had a higher number of CD4+ regulatory cells and a better treatment response compared with other patients. In the nonresponder group, T-cell enrichment progressed to secondary B-cell enrichment and subsequently diffuse large B-cell lymphoma. Moreover, AITL patients with lymphoma-associated hemophagocytic syndrome had more T follicular helper (Tfh) cells with copy number variations in CHR5. To our knowledge, this study is the first to reveal the single-cell landscape of BM microenvironment heterogeneity in PTCL patients with BMI. scRNA-seq can be used to investigate the immune heterogeneity and genetic variations in AITL associated with prognosis.

Individualized dynamic risk assessment for multiple myeloma

Background

Individualized treatment decisions for patients with multiple myeloma (MM) requires accurate risk stratification that takes into account patient-specific consequences of genetic abnormalities and tumor microenvironment on disease outcome and therapy responsiveness.

Methods

Previously, SYstems Genetic Network AnaLysis (SYGNAL) of multi-omics tumor profiles from 881 MM patients generated the mmSYGNAL network, which uncovered different causal and mechanistic drivers of genetic programs associated with disease progression across MM subtypes. Here, we have trained a machine learning (ML) algorithm on activities of mmSYGNAL programs within individual patient tumor samples to develop a risk classification scheme for MM that significantly outperformed cytogenetics, International Staging System, and multi-gene biomarker panels in predicting risk of PFS across four independent patient cohorts.

Results

We demonstrate that, unlike other tests, mmSYGNAL can accurately predict disease progression risk at primary diagnosis, pre- and post-transplant and even after multiple relapses, making it useful for individualized dynamic risk assessment throughout the disease trajectory.

Conclusion

mmSYGNAL provides improved individualized risk stratification that accounts for a patient's distinct set of genetic abnormalities and can monitor risk longitudinally as each patient's disease characteristics change.

A comparison of the International Consensus and 5th WHO classifications of T-cell lymphomas and histiocytic/dendritic cell tumours

Since the publication in 2017 of the revised 4th Edition of the World Health Organization (WHO) classification of haematolymphoid tumours, here referred to as WHO-HAEM4, significant clinicopathological, immunophenotypic and molecular advances have been made in the field of lymphomas, contributing to refining the diagnostic criteria of several diseases, upgrading entities previously defined as provisional and identifying new entities. This process has resulted in two recent classification proposals of lymphoid neoplasms: the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In this paper, we review and compare the two classifications in terms of diagnostic criteria and entity definition, focusing on T-cell lymphomas and histiocytic/dendritic cell tumours. Moreover, we update the genetic data of the various pathological entities. The main goal is to provide a tool to facilitate the work of the pathologists, haematologists and researchers involved in the diagnosis and treatment of these haematological malignancies.

A Comparison of the Fifth World Health Organization and the International Consensus Classifications of Mature T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCLs) are a rare subset of non-Hodgkin lymphomas that often carry significant difficulty in diagnosis and classification because of their rarity and biological complexity. Previous editions of the World Health Organization (WHO) classifications of hemopoietic neoplasms in 2001, 2008, and 2017 aimed to standardize hemopoietic neoplasm diagnosis in general. Since then, crucial clinico-pathological, immunophenotypic, and recent molecular discoveries have been made in the field of lymphomas, contributing to refining diagnostic criteria of several diseases, upgrading entities previously defined as provisional, and identifying new entities. In 2022, two different models were proposed to classify hematolymphoid neoplasms: the 5th edition of the WHO classification (WHO-HAEM5) and the International Consensus Classification (ICC). Of note, a common nosography is mandatory to ensure progress in health science and ensure the basis for a real precision medicine. In this article, the authors summarized the main differences with the previous fourth WHO edition and reviewed the main discrepancies between the two newest classifications, as far as PTCLs are concerned.

Involvement of spleen is associated with shorter survival in patients with angioimmunoblastic T cell lymphoma

BACKGROUND

The prognosis of patients with angioimmunoblastic T cell lymphoma (AITL) remains dismal, with their 5-year overall survival (OS) and progression-free survival (PFS) rates of 32-41% and 18-38%, respectively. Spleen involvement occurs in a proportion of patients with AITL. But still, it is unclear whether spleen involvement impacts the prognosis of AITL patients. In this study, we aim to establish new prognostic indicators for the identification of high-risk patients to draft optimal treatment regimens.

METHODS

We collected and counted the clinical data of 54 patients with AITL treated with CHOP-based first-line chemotherapy regimen between 2010 and 2021 at Hubei Cancer Hospital and Hunan Cancer Hospital. In addition, all patients received PET-CT scan prior to receiving treatment. We performed univariate and multivariate analyses to assess the predictive role of tumor characteristics, laboratory, and radiographic data for the prognosis of AITL.

RESULTS

We observed that PFS and OS are worse in patients with high ECOG scores, spleen involvement, and low serum albumin levels in patients with AITL. In univariate analysis, stage (HR 3.515 [1.142-10.822], p = 0.028) and spleen involvement (HR 8.378 [1.085-64.696, p = 0.042) were correlated with PFS in patients with AITL. Besides, stage (HR 3.439 [1.108-10.674], p = 0.033) and spleen involvement (HR 11.002 [1.420-85.254], p = 0.022) were significantly correlated with OS. Consistently, spleen involvement was correlated with OS (HR 16.571 [1.350-203.446], p = 0.028) and PFS (HR 10.905 [1.037-114.690], p = 0.047) in AITL patients in a multivariate analysis.

CONCLUSION

This study demonstrates that spleen involvement might be used as a prognostic indicator for AITL patients.

Follicular helper T-cell lymphomas: disease spectrum, relationship with clonal hematopoiesis, and mimics. A report of the 2022 EA4HP/SH lymphoma workshop

Follicular helper T-cell lymphomas (TFH lymphomas) were discussed in session V of the lymphoma workshop of the European Association for Haematopathology (EA4HP)/Society for Hematopathology (SH) 2022 meeting in Florence, Italy. The session focused on the morphologic spectrum of TFH lymphoma, including its three subtypes: angioimmunoblastic-type (AITL), follicular-type, and not otherwise specified (NOS). The submitted cases encompassed classic examples of TFH lymphoma and unusual cases such as those with early or indolent presentations, associated B-cell proliferations, or Hodgkin/Reed-Sternberg-like cells. The relationship between TFH lymphoma and clonal hematopoiesis was highlighted by several cases documenting divergent evolution of myeloid neoplasm and AITL from shared clonal mutations. The distinction between TFH lymphoma and peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS), was stressed, and many challenging examples were presented. Various cases highlighted the difficulties of differentiating TFH lymphoma from other established types of lymphoma and reactive conditions. Cutaneous T-cell lymphoma expressing TFH markers, particularly when resulting in lymph node involvement, should be distinguished from TFH lymphomas. Additional immunophenotyping and next-generation sequencing studies were performed on various cases in this session, highlighting the importance of these technologies to our current understanding and classification of TFH lymphomas.

The RHOA Mutation G17V Does Not Lead to Increased Migration of Human Malignant T Cells but Is Associated with Matrix Remodelling

Nodal T-follicular helper cell lymphoma, angioimmunoblastic-type (AITL), is characterized by constitutional symptoms, advanced-stage disease, and generalized lymphadenopathy. A genetic hallmark of this lymphoma is the frequent occurrence of the RHOA mutation G17V in neoplastic cells, which is observed in around 60% of patients. Because RHOA is involved in both T-cell receptor downstream signalling and cell migration, we hypothesized that the characteristic presentation of AITL could be the result of enhanced tumor cell migration. Therefore, this study aimed to elucidate the impact of the RHOA variant G17V on the migration of neoplastic T cells. We transfected the T-cell lymphoma cell lines HH and HuT78 to stably express the RHOA-G17V variant. RHOA-G17V-expressing T cells did not exhibit enhanced motility compared to empty-vector-transfected cells in microchannels, a 3D collagen gel, or primary human lymphatic tissue. Cells of the HH cell line expressing RHOA-G17V had an increased number of cells with cleaved collagen compared with the empty-vector-transfected cells. Therefore, we hypothesized that the early spread of AITL tumor cells may be related to remodelling of the extracellular matrix. Accordingly, we observed a significant negative correlation between the relative area of collagen in histological sections from 18 primary AITL and the allele frequency of the RHOA-G17V mutation. In conclusion, our results suggest that the characteristic presentation of AITL with early, widespread dissemination of lymphoma cells is not the result of an enhanced migration capacity due to the RHOA-G17V mutation; instead, this feature may rather be related to extracellular matrix remodelling.

DNMT3AR882H accelerates angioimmunoblastic T-cell lymphoma in mice

DNA methylation-related genes, including TET2, IDH2, and DNMT3A are highly frequently mutated in angioimmunoblastic T-cell lymphoma (AITL), an aggressive malignancy of T follicular helper (Tfh) cells associated with aberrant immune features. It has been shown that TET2 loss cooperates with RHOA^G17V to promote AITL in mice but the functional role of DNMT3A mutations in AITL remains unclear. Here, we report that DNMT3A^R882H, the most common mutation of DNMT3A in AITL, accelerates the development of Tet2^-/-; RHOA^G17V AITL in mice, indicated by the expansion of malignant Tfh cells and aberrant B cells, skin rash, and significantly shortened disease-free survival. To understand the underlying cellular and molecular mechanisms, we performed single-cell transcriptome analyses of lymph nodes of mice transplanted with Tet2^-/-, Tet2^-/-; RHOA^G17V or DNMT3A^R882H; Tet2^-/-; RHOA^G17V hematopoietic stem and progenitor cells. These single-cell landscapes reveal that DNMT3A mutation further activates Tfh cells and leads to rapid and terminal differentiation of B cells, probably through enhancing the interacting PD1/PD-L1, ICOS/ICOSL, CD28/CD86, and ICAM1/ITGAL pairs. Our study establishes the functional roles of DNMT3A mutation in AITL and sheds light on the molecular mechanisms of this disease.

Pathologic and molecular insights in nodal T-follicular helper cell lymphomas

T-follicular helper (TFH) cells are one of the T-cell subsets with a critical role in the regulation of germinal center (GC) reactions. TFH cells contribute to the positive selection of GC B-cells and promote plasma cell differentiation and antibody production. TFH cells express a unique phenotype characterized by PD-1^hi, ICOS^hi, CD40L^hi, CD95^hi, CTLA^hi, CCR7^lo, and CXCR5^hi . Three main subtypes of nodal TFH lymphomas have been described: 1) angioimmunoblastic-type, 2) follicular-type, and 3) not otherwise specified (NOS). The diagnosis of these neoplasms can be challenging, and it is rendered based on a combination of clinical, laboratory, histopathologic, immunophenotypic, and molecular findings. The markers most frequently used to identify a TFH immunophenotype in paraffin-embedded tissue sections include PD-1, CXCL13, CXCR5, ICOS, BCL6, and CD10. These neoplasms feature a characteristic and similar, but not identical, mutational landscape with mutations in epigenetic modifiers (TET2, DNMT3A, IDH2), RHOA, and T-cell receptor signaling genes. Here, we briefly review the biology of TFH cells and present a summary of the current pathologic, molecular, and genetic features of nodal lymphomas. We want to highlight the importance of performing a consistent panel of TFH immunostains and mutational studies in TCLs to identify TFH lymphomas.

Tyrosine kinases in nodal peripheral T-cell lymphomas

Nodal peripheral T-cell lymphomas (PTCL) are uncommon and heterogeneous tumors characterized by a dismal prognosis. Targeted therapy has been proposed. However, reliable targets are mostly represented by a few surface antigens (e.g., CD52 and CD30), chemokine receptors (e.g., CCR4), and epigenetic gene expression regulation. In the last two decades, however, several studies have supported the idea that tyrosine kinase (TK) deregulation might be relevant for both the pathogenesis and treatment of PTCL. Indeed, they can be expressed or activated as a consequence of their involvement in genetic lesions, such as translocations, or by ligand overexpression. The most striking example is ALK in anaplastic large-cell lymphomas (ALCL). ALK activity is necessary to support cell proliferation and survival, and its inhibition leads to cell death. Notably, STAT3 was found to be the main downstream ALK effector. Other TKs are consistently expressed and active in PTCLs, such as PDGFRA, and members of the T-cell receptor signaling family, such as SYK. Notably, as in the case of ALK, STAT proteins have emerged as key downstream factors for most of the involved TK.

Mature T-cell and NK-cell lymphomas: updates on molecular genetic features

Mature T-cell and NK-cell lymphomas are a heterogeneous group of rare and typically aggressive neoplasms. Diagnosis and subclassification have historically relied primarily on the integration of clinical, histologic, and immunophenotypic features, which often overlap. The widespread application of a variety of genomic techniques in recent years has provided extensive insight into the pathobiology of these diseases, allowing for more precise diagnostic classification, improved prognostication, and development of novel therapies. In this review, we summarize the genomic features of the most common types of mature T-cell and NK-cell lymphomas with a particular focus on the contribution of genomics to biologic insight, classification, risk stratification, and select therapies in the context of the recently published International Consensus and updated World Health Organization classification systems.

Classification and diagnostic evaluation of nodal T- and NK-cell lymphomas

Nodal T- and NK-cell lymphomas are among the most frequent T-cell malignancies and most subtypes have aggressive clinical behavior. Evolving understanding of the biology and molecular characteristics of these lymphomas, as well as the development of new precision therapy approaches, underscores the importance of ongoing updates to the classification and diagnostic evaluation of this group of malignancies. Here, we discuss the classification of nodal T- and NK-cell lymphomas based on the 2022 International Consensus Classification of Mature Lymphoid Neoplasms (2022 ICC). Lymphomas of T-follicular helper cell origin are now grouped into a single entity, follicular helper T-cell lymphoma (TFH lymphoma), with three subtypes (angioimmunoblastic-type, follicular-type, and not otherwise specified), reflecting their common cellular origin and shared molecular and clinical characteristics. Classification of anaplastic large cell lymphoma (ALCL) remains essentially unchanged; DUSP22-rearranged cases are now considered a genetic subtype of ALK-negative ALCL. Primary nodal EBV-positive T-/NK-cell lymphoma is introduced as a new provisional entity; these cases were previously considered a variant of peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS). PTCL, NOS remains a diagnosis of exclusion, with evolving molecular data indicating the presence of distinct subgroups, including PTCL-TBX21, PTCL-GATA3, and EBV-negative cytotoxic PTCLs. We also discuss diagnostic strategies to facilitate the 2022 ICC classification among nodal T- and NK-cell lymphomas and the distinction from nodal involvement by extranodal neoplasms.

RHOA G17V induces T follicular helper cell specification and involves angioimmunoblastic T-cell lymphoma via upregulating the expression of PON2 through an NF-κB-dependent mechanism

Angioimmunoblastic T-cell lymphoma (AITL) is a malignant hematologic tumor arising from T follicular helper (Tfh) cells. High-throughput genomic sequencing studies have shown that AITL is characterized by a novel highly recurring somatic mutation in RHOA, encoding p.Gly17Val (RHOA G17V). However, the specific role of RHOA G17V in AITL remains unknown. Here, we demonstrated that expression of Rhoa G17V in CD4⁺ T cells increased cell proliferation and induces Tfh cell specification associated with Pon2 upregulation through an NF-κB-dependent mechanism. Further, loss of Pon2 attenuated oncogenic function induced by genetic lesions in Rhoa. In addition, an abnormality of RHOA G17V mutation and PON2 expression is also detected in patients with AITL. Our findings suggest that PON2 associated with RHOA G17V mutation might control the direction of the molecular agents-based AITL and provide a new therapeutic target in AITL.

Impact of rituximab on treatment outcomes of patients with angioimmunoblastic T-cell lymphoma; a population-based analysis

BACKGROUND

Patients with angioimmunoblastic T-cell lymphoma (AITL) are treated with cyclophosphamide, doxorubicin, vincristine and prednisone with or without etoposide (CHO(E)P). In the majority of cases, Epstein-Barr virus (EBV)-positive B-cells are present in the tumour. There is paucity of research examining the effect of rituximab when added to CHO(E)P. In this nationwide, population-based study, we analysed the impact of rituximab on overall response rate (ORR), progression-free survival (PFS) and overall survival (OS) of patients with AITL.

METHODS

Patients with AITL diagnosed between 2014 and 2020 treated with ≥one cycle of CHO(E)P with or without rituximab were identified in the Netherlands Cancer Registry. Survival follow-up was up to 1st February 2022. Baseline characteristics, best response during first-line treatment and survival were collected. PFS was defined as the time from diagnosis to relapse or to all-cause-death. OS was defined as the time from diagnosis to all-cause-death. Multivariable analysis for the risk of mortality was performed using Cox regression.

FINDINGS

Out of 335 patients, 146 patients (44%) received R-CHO(E)P. Rituximab was more frequently used in patients with a B-cell infiltrate (71% versus 89%, p < 0·01). The proportion of patients who received autologous stem cell transplantation (ASCT) was similar between CHO(E)P and R-CHO(E)P (27% versus 30%, respectively). The ORR and 2-year PFS for patients who received CHO(E)P and R-CHO(E)P were 71% and 78% (p = 0·01), and 40% and 45% (p = 0·12), respectively. The 5-year OS was 47% and 40% (p = 0·99), respectively. In multivariable analysis, IPI-score 3-5, no B-cell infiltrate and no ASCT were independent prognostic factors for risk of mortality, whereas the use of rituximab was not.

INTERPRETATION

Although the addition of rituximab to CHO(E)P improved ORR for patients with AITL, the PFS and OS did not improve.

The International Consensus Classification of Mature Lymphoid Neoplasms: a report from the Clinical Advisory Committee

Since the publication of the Revised European-American Classification of Lymphoid Neoplasms in 1994, subsequent updates of the classification of lymphoid neoplasms have been generated through iterative international efforts to achieve broad consensus among hematopathologists, geneticists, molecular scientists, and clinicians. Significant progress has recently been made in the characterization of malignancies of the immune system, with many new insights provided by genomic studies. They have led to this proposal. We have followed the same process that was successfully used for the third and fourth editions of the World Health Organization Classification of Hematologic Neoplasms. The definition, recommended studies, and criteria for the diagnosis of many entities have been extensively refined. Some categories considered provisional have now been upgraded to definite entities. Terminology for some diseases has been revised to adapt nomenclature to the current knowledge of their biology, but these modifications have been restricted to well-justified situations. Major findings from recent genomic studies have impacted the conceptual framework and diagnostic criteria for many disease entities. These changes will have an impact on optimal clinical management. The conclusions of this work are summarized in this report as the proposed International Consensus Classification of mature lymphoid, histiocytic, and dendritic cell tumors.

Epstein-Barr Virus (EBV) Is Mostly Latent and Clonal in Angioimmunoblastic T Cell Lymphoma (AITL)

The Epstein-Barr virus (EBV) is associated with angioimmunoblastic T cell lymphoma (AITL), a peripheral T lymphoma of poor prognosis in at least 90% of cases. The role of EBV in this pathology is unknown. Using next-generation sequencing, we sequenced the entire EBV genome in biopsies from 18 patients with AITL, 16 patients with another EBV-associated lymphoma, and 2 controls. We chose an EBV target capture method, given the high specificity of this technique, followed by a second capture to increase sensitivity. We identified two main viral strains in AITL, one of them associated with the mutations BNRF1 S542N and BZLF1 A206S and with mutations in the EBNA-3 and LMP-2 genes. This strain was characterized in patients with short post-diagnosis survival. The main mutations found during AITL on the most mutated latency or tegument genes were identified and discussed. We showed that the virus was clonal in all the AITL samples, suggesting that it may be involved in this pathology. Additionally, EBV was latent in all the AITL samples; for one sample only, the virus was found to be latent and probably replicative, depending on the cells. These various elements support the role of EBV in AITL.

Human Germinal Center-associated Lymphoma (HGAL) Is a Reliable Marker of Normal and Neoplastic Follicular Helper T Cells Including Angioimmunoblastic T-Cell Lymphoma

The diagnosis of angioimmunoblastic T-cell lymphoma (AITL) is complex and requires the demonstration of a T-follicular helper (TFH) phenotype. Immunophenotypic markers that detect the TFH phenotype are highly variable, thereby necessitating the use of 3 to 5 TFH markers to substantiate a TFH phenotype. We tested the utility of germinal center markers human germinal center-associated lymphoma (HGAL) and LIM-domain only 2 (LMO2) in detecting a TFH phenotype. We compared their staining to that of 6 TFH markers in current use, PD-1, ICOS, CXCL13, SAP, CD10, and BCL6, in a cohort of 23 AITL. Our results show that although both markers can detect a TFH phenotype, HGAL was superior to LMO2 in the percent of cells stained and the intensity of staining, 2 variables used to generate H-scores. Using H-scores as the metric, HGAL was most comparable to BCL6 among the currently used TFH markers and was more sensitive than CXCL13, SAP, CD10, and LMO2. PD-1 and ICOS emerged as the most robust of the 8 markers tested in this study in detecting a TFH phenotype. We conclude that HGAL is a reliable marker of TFH cells and can aid in the diagnosis of lymphomas of TFH derivation, particularly in the recognition of early patterns of AITL.

Cancer-associated mutations in VAV1 trigger variegated signaling outputs and T-cell lymphomagenesis

Mutations in VAV1, a gene that encodes a multifunctional protein important for lymphocytes, are found at different frequencies in peripheral T‐cell lymphoma (PTCL), non‐small cell lung cancer, and other tumors. However, their pathobiological significance remains unsettled. After cataloguing 51 cancer‐associated VAV1 mutations, we show here that they can be classified in five subtypes according to functional impact on the three main VAV1 signaling branches, GEF‐dependent activation of RAC1, GEF‐independent adaptor‐like, and tumor suppressor functions. These mutations target new and previously established regulatory layers of the protein, leading to quantitative and qualitative changes in VAV1 signaling output. We also demonstrate that the most frequent VAV1 mutant subtype drives PTCL formation in mice. This process requires the concurrent engagement of two downstream signaling branches that promote the chronic activation and transformation of follicular helper T cells. Collectively, these data reveal the genetic constraints associated with the lymphomagenic potential of VAV1 mutant subsets, similarities with other PTCL driver genes, and potential therapeutic vulnerabilities.

Emerging Therapeutic Landscape of Peripheral T-Cell Lymphomas Based on Advances in Biology: Current Status and Future Directions

Simple Summary

Peripheral T-cell lymphoma is a rare but aggressive tumor. Due to its rarity, the disease has not been completely understood. In our review, we look at this lymphoma at the molecular level based on available literature. We highlight the mechanism behind the progression and resistance of this tumor. In doing so, we bring forth possible mechanism that could be exploited through novel chemotherapy drugs. In addition, we also look at the current available drugs used in treating this disease, as well as highlight other new drugs, describing their potential in treating this lymphoma. We comprehensively have collected and present the available biology behind peripheral T-cell lymphoma and discuss the available treatment options.

Abstract

T-cell lymphomas are a relatively rare group of malignancies with a diverse range of pathologic features and clinical behaviors. Recent molecular studies have revealed a wide array of different mechanisms that drive the development of these malignancies and may be associated with resistance to therapies. Although widely accepted chemotherapeutic agents and combinations, including stem cell transplantation, obtain responses as initial therapy for these diseases, most patients will develop a relapse, and the median survival is only 5 years. Most patients with relapsed disease succumb within 2 to 3 years. Since 2006, the USFDA has approved five medications for treatment of these diseases, and only anti-CD30-therapy has made a change in these statistics. Clearly, newer agents are needed for treatment of these disorders, and investigators have proposed studies that evaluate agents that target these malignancies and the microenvironment depending upon the molecular mechanisms thought to underlie their pathogenesis. In this review, we discuss the currently known molecular mechanisms driving the development and persistence of these cancers and discuss novel targets for therapy of these diseases and agents that may improve outcomes for these patients.

Genome-Wide miRNA Expression Profiling of Molecular Subgroups of Peripheral T-cell Lymphoma

PURPOSE

Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of non-Hodgkin lymphomas with aggressive clinical behavior. We performed comprehensive miRNA profiling in PTCLs and corresponding normal CD4⁺ Th1/2 and TFH-like polarized subsets to elucidate the role of miRNAs in T-cell lymphomagenesis.

EXPERIMENTAL DESIGN

We used nCounter (NanoString Inc) for miRNA profiling and validated using Taqman qRT-PCR (Applied Biosystems, Inc). Normal CD4⁺ T cells were polarized into effector Th subsets using signature cytokines, and miRNA significance was revealed using functional experiments.

RESULTS

Effector Th subsets showed distinct miRNA expression with corresponding transcription factor expression (e.g., BCL6/miR-19b, -106, -30d, -26b, in IL21-polarized; GATA3/miR-155, miR-337 in Th2-polarized; and TBX21/miR-181a, -331-3p in Th1-polarized cells). Integration of miRNA signatures suggested activation of TCR and PI3K signaling in IL21-polarized cells, ERK signaling in Th1-polarized cells, and AKT-mTOR signaling in Th2-polarized cells, validated at protein level. In neoplastic counterparts, distinctive miRNAs were identified and confirmed in an independent cohort. Integrative miRNA-mRNA analysis identified a decrease in target transcript abundance leading to deregulation of sphingolipid and Wnt signaling and epigenetic dysregulation in angioimmunoblastic T-cell lymphoma (AITL), while ERK, MAPK, and cell cycle were identified in PTCL subsets, and decreased target transcript abundance was validated in an independent cohort. Elevated expression of miRNAs (miR-126-3p, miR-145-5p) in AITL was associated with poor clinical outcome. In silico and experimental validation suggest two targets (miR-126→ SIPR2 and miR-145 → ROCK1) resulting in reduced RhoA-GTPase activity and T-B-cell interaction.

CONCLUSIONS

Unique miRNAs and deregulated oncogenic pathways are associated with PTCL subtypes. Upregulated miRNA-126-3p and miR-145-5p expression regulate RhoA-GTPase and inhibit T-cell migration, crucial for AITL pathobiology.

Phase 1 trial of carfilzomib in relapsed/refractory peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCL) are a unique subset of lymphomas with a poor prognosis due to limited treatment options. We performed a phase 1 study of carfilzomib in patients with relapsed/refractory PTCL to determine the safety profile and the maximum tolerated dose (MTD) of this agent. The study was a classical 3 + 3 phase 1 design with intra-patient dose escalation allowed beginning on day 8 of cycle 1 and subsequently. Dose-limiting toxicity (DLT) was defined as the occurrence of any grade 3/4 adverse event. Carfilzomib was given on days 1, 2, 8, 9, 15, and 16 of a 28-day cycle. Fifteen patients were enrolled from 3 centers. The median age of patients was 62. The median number of prior therapies for subjects on this trial was five. The MTD of carfilzomib was 36 mg/m². Dose-limiting toxicities included anemia and sepsis. Serious adverse events were seen in 45% of patients. Single-agent carfilzomib leads to a complete response in one patient and a partial response in one patient. Overall, the drug was reasonably tolerated for a heavily pretreated population, but the limited response rate and short duration of response demonstrate a lack of promise for carfilzomib as a single agent in this patient population.

The Early Diagnostic Dilemma in Angioimmunoblastic T Cell Lymphoma with Excessive Plasma Cells Proliferation

Background

Angioimmunoblastic T cell lymphoma (AITL) is an aggressive Epstein–Barr virus-associated T cell lymphoma. Clinical syndromes of AITL are not confined to fever and lymphadenopathy, and patients may initially present with polyclonal plasma cell proliferation, which may obscure the underlying disease of AITL, delaying diagnosis. Case Presentation. Here, we report two AITL patients with excessive plasma cell proliferation in the bone marrow, peripheral blood, and ascites even mimicking plasma cell leukemia. Both of them had poor endings.

Conclusions

Our report emphasizes the complexity of the clinical manifestations of AITL, which aims to increase the alertness of physicians and improve the rate of early diagnosis. Integrated diagnostic approaches such as histopathology, flow cytometry, cytogenetics, and molecular biology are essential for accurate diagnosis and precise therapy.

How I Diagnose Angioimmunoblastic T-Cell Lymphoma

OBJECTIVES

Angioimmunoblastic T-cell lymphoma (AITL) is a subtype of peripheral T-cell lymphoma derived from T-follicular helper cells. For pathologists, diagnosing AITL may be challenging due to its wide clinical and histopathologic spectrum, which can mimic a variety of reactive and neoplastic processes.

METHODS

We summarize and discuss the clinicopathologic features of AITL, emphasizing diagnostic tools available to the practicing pathologist. Common diagnostic dilemmas are discussed.

RESULTS

AITL exhibits various histologic patterns and is often associated with a prominent microenvironment that can obscure the neoplastic cells. Atypical B-cell proliferations, which can take a number of forms, are common in AITL, and clonal B-cell expansion can be seen. The atypical B cells can closely resemble Hodgkin/Reed-Sternberg cells, leading to misdiagnosis as classic Hodgkin lymphoma. Molecular studies have revealed recurrent genetic alterations, which can aid in differential diagnosis, particularly in problematic cases.

CONCLUSIONS

Given the complex diagnostic challenges in AITL, an integrated approach, incorporating clinical, morphologic, immunophenotypic, and molecular findings, is helpful to reach an accurate diagnosis.

Role of Microenvironment in Non-Hodgkin Lymphoma: Understanding the Composition and Biology

Lymphoma microenvironment is a dynamic and well-orchestrated network of various immune and stromal cells that is indispensable for tumor cell survival, growth, migration, immune escape, and drug resistance. Recent progress has enhanced our knowledge of the pivotal role of microenvironment in lymphomagenesis. Understanding the characteristics, functions, and contributions of various components of the tumor niche, along with its bidirectional interactions with tumor cells, is paramount. It offers the potential to identify new therapeutic targets with the ability to restore antitumor immune surveillance and eliminate the protumoral factors contributed by the tumor niche.

Molecular understanding of peripheral T-cell lymphomas, not otherwise specified (PTCL, NOS): A complex disease category

Peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) includes various diseases. Attempts have been made to identify distinct properties of disease within the PTCL, NOS classification and evaluate their significance to prognosis. Comprehensive gene expression analysis and evaluation of genomic abnormalities have successfully identified specific diseases from heterogeneous PTCL, NOS cases. For example, cases with properties of T follicular helper cells have been identified and classified as an entity resembling angioimmunoblastic T-cell lymphoma (AITL), based on both immunohistochemistry and genomic features. Here, we focus on the molecular pathology of PTCL, NOS and discuss recent changes relevant to its classification.

The mutation of BCOR is highly recurrent and oncogenic in mature T-cell lymphoma

Background

BCOR acts as a corepressor of BCL6, a potent oncogenic protein in cancers of the lymphoid lineage. We have found the recurrent somatic mutation of BCOR occurred in mature T-cell lymphoma (TCL). The role of BCOR mutation in lymphoid malignancies is unknown.

Methods

Lymphoma patient samples were analyzed to identify missense mutations in BCOR using Sanger sequencing. Transfection, RNA interference, immunoprecipitation, western blotting, cell proliferation, cytokine assays and quantitative real-time PCR were employed to determine the functional relevance of the novel K607E mutation in BCOR. The significant transcriptional changes were analyzed by performing DNA microarray profiling in cells expressing BCOR K607E mutant.

Results

One hundred thirty-seven lymphoma patient samples were analyzed to identify K607E mutation of the BCOR gene. The BCOR K607E mutation was identified in 15 of 47 NK/T cell lymphoma cases (31.9%), 2 of 18 angioimmunoblastic T-cell lymphoma cases (11.1%), 10 of 30 peripheral T-cell lymphoma, not otherwise specified cases (33.3%), and 13 of 42 diffuse large B-cell lymphoma cases (30.9%). Molecular analysis of BCOR K607E mutation revealed that compared to the wild-type BCOR, the mutant BCOR bound to the BCL6, PCGF1, and RING1B proteins with lesser affinity. Ectopic expression of BCOR K607E mutant significantly enhanced cell proliferation, AKT phosphorylation and the expression of interleukin-2 (IL-2) with up-regulated expression of HOX and S100 protein genes in T cells. BCOR silencing also significantly enhanced cell proliferation, AKT phosphorylation, and IL-2 production.

Conclusions

Functional analyses indicated that K607E mutation of BCOR is oncogenic in nature and can serve as a genetic marker of T-cell lymphoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07806-8.

Linking the KIR phenotype with STAT3 and TET2 mutations to identify chronic lymphoproliferative disorders of NK cells

Distinguishing chronic lymphoproliferative disorders of NK cells (CLPD-NK) from reactive NK-cell expansion is challenging. We assessed the value of killer immunoglobulin-like receptor(KIR) phenotyping and targeted high-throughput sequencing in a cohort of 114 consecutive patients with NK cell proliferation, retrospectively assigned to a CLPD-NK group (n = 46) and a reactive NK group (n = 68). We then developed an NK-cell clonality score combining flow cytometry and molecular profiling with a positive predictive value of 93%. STAT3 and TET2 mutations were respectively identified in 27% and 34% of the patients with CLPD-NK, constituting a new diagnostic hallmark for this disease. TET2-mutated CLPD-NK preferentially exhibited a CD16low phenotype, more frequently displayed a lower platelet count, and was associated with other hematologic malignancies such as myelodysplasia. To explore the mutational clonal hierarchy of CLPD-NK, we performed whole-exome sequencing of sorted, myeloid, T, and NK cells and found that TET2 mutations were shared by myeloid and NK cells in 3 of 4 cases. Thus, we hypothesized that TET2 alterations occur in early hematopoietic progenitors which could explain a potential link between CLPD-NK and myeloid malignancies. Finally, we analyzed the transcriptome by RNA sequencing of 7 CLPD-NK and evidenced 2 groups of patients. The first group displayed STAT3 mutations or SOCS3 methylation and overexpressed STAT3 target genes. The second group, including 2 TET2-mutated cases, significantly underexpressed genes known to be downregulated in angioimmunoblastic T-cell lymphoma. Our results provide new insights into the pathogenesis of NK-cell proliferative disorders and, potentially, new therapeutic opportunities.

Case Report: Composite Angioimmunoblastic T-Cell Lymphoma and Epstein-Barr Virus-Positive B-Cell Lymphoproliferative Disorder as Other Iatrogenic Immunodeficiency-Associated Lymphoproliferative Disorders

Immunosuppressants are widely used to treat patients with rheumatoid arthritis (RA), and their adverse effects have been known to cause other iatrogenic immunodeficiency-associated lymphoproliferative disorders (OIIA-LPDs). We report a patient with RA who had been treated with methotrexate (MTX) and tacrolimus (TAC) and who developed whole body lymphadenopathy. We simultaneously confirmed angioimmunoblastic T-cell lymphoma (AITL) through a right cervical lymph node biopsy and Epstein-Barr virus-positive B-cell lymphoproliferative disorder (EBV-positive B-LPD) through a bone marrow examination. After cessation of immunosuppressant therapy, both LPDs completely disappeared. Patients with AITL are occasionally reported to develop B-cell lymphoma through reactivation of the EBV, which leads to clonal expansion in the microenvironment. Immunohistochemistry results revealed that both LPD components were positive for EBV-encoded RNA. Moreover, in this patient, the plasma EBV DNA level was found to be high; therefore, EBV infection was a probable etiology. Synchronous coexistence of AITL and B-LPD as an OIIA-LPD has rarely been reported. This case report is the first to discuss the disappearance of both LPDs on withdrawal of immunosuppressants only. AITL occasionally accompany B-LPD; however, this composite lymphoma comprised AITL and B-LPD, and OIIA-LPDs should not be overlooked.

B Cells versus T Cells in the Tumor Microenvironment of Malignant Lymphomas. Are the Lymphocytes Playing the Roles of Muhammad Ali versus George Foreman in Zaire 1974?

Malignant lymphomas are a heterogeneous group of malignancies that develop both in nodal and extranodal sites. The different tissues involved and the highly variable clinicopathological characteristics are linked to the association between the lymphoid neoplastic cells and the tissues they infiltrate. The immune system has developed mechanisms to protect the normal tissue from malignant growth. In this review, we aim to explain how T lymphocyte-driven control is linked to tumor development and describe the tumor-suppressive components of the resistant framework. This manuscript brings forward a new insight with regard to intercellular and intracellular signaling, the immune microenvironment, the impact of therapy, and its predictive implications. A better understanding of the key components of the lymphoma environment is important to properly assess the role of both B and T lymphocytes, as well as their interplay, just as two legendary boxers face each other in a heavyweight title final, as was the case of Ali versus Foreman.

New preclinical models for angioimmunoblastic T-cell lymphoma: filling the GAP

Mouse models are essential to study and comprehend normal and malignant hematopoiesis. The ideal preclinical model should mimic closely the human malignancy. This means that these mice should recapitulate the clinical behavior of the human diseases such as cancer and therapeutic responses with high reproducibility. In addition, the genetic mutational status, the cell phenotype, the microenvironment of the tumor and the time until tumor development occurs, should be mimicked in a preclinical model. This has been particularly challenging for human angioimmunoblastic lymphoma (AITL), one of the most prominent forms of peripheral T-cell lymphomas. A complex network of interactions between AITL tumor cells and the various cells of the tumor microenvironment has impeded the study of AITL pathogenesis in vitro. Very recently, new mouse models that recapitulate faithfully the major features of human AITL disease have been developed. Here, we provide a summary of the pathology, the transcriptional profile and genetic and immune-phenotypic features of human AITL. In addition, we give an overview of preclinical models that recapitulate more or less faithfully human AITL characteristics and pathology. These recently engineered mouse models were essential in the evaluation of novel therapeutic agents for possible treatment of AITL, a malignancy in urgent need of new treatment options.

Rare non-Hodgkin lymphoma of childhood and adolescence: A consensus diagnostic and therapeutic approach to pediatric-type follicular lymphoma, marginal zone lymphoma, and nonanaplastic peripheral T-cell lymphoma

Pediatric-type follicular (PTFL), marginal zone (MZL), and peripheral T-cell lymphoma (PTCL) account each for <2% of childhood non-Hodgkin lymphoma. We present clinical and histopathological features of PTFL, MZL, and few subtypes of PTCL and provide treatment recommendations. For localized PTFL and MZL, watchful waiting after complete resection is the therapy of choice. For PTCL, therapy is subtype-dependent and ranges from a block-like anaplastic large cell lymphoma (ALCL)-derived and, alternatively, leukemia-derived therapy in PTCL not otherwise specified and subcutaneous panniculitis-like T-cell lymphoma to a block-like mature B-NHL-derived or, preferentially, ALCL-derived treatment followed by hematopoietic stem cell transplantation in first remission in hepatosplenic and angioimmunoblastic T-cell lymphoma.

A comprehensive analysis of RHOA mutation positive and negative angioimmunoblastic T-cell lymphomas by targeted deep sequencing, expression profiling and single cell digital image analysis

Angioimmunoblastic T-cell lymphoma (AITL) is a uniquely aggressive mature T-cell neoplasm. In recent years, recurrent genetic mutations in ras homolog family member A (RHOA), tet methylcytosine dioxygenase 2 (TET2), DNA methyltransferase 3 alpha (DNMT3A) and isocitrate dehydrogenase [NADP(+)] 2 (IDH2) have been identified as associated with AITL. However, a deep molecular study assessing both DNA mutations and RNA expression profile combined with digital image analysis is lacking. The present study aimed to evaluate the significance of molecular and morphologic features by high resolution digital image analysis in several cases of AITL. To do so, a total of 18 separate tissues from 10 patients with AITL were collected and analyzed. The results identified recurrent mutations in RHOA, TET2, DNMT3A, and IDH2, and demonstrated increased DNA mutations in coding, promoter and CCCTC binding factor (CTCF) binding sites in RHOA mutated AITLs vs. RHOA non-mutated cases, as well as increased overall survival in RHOA mutated patients. In addition, single cell computational digital image analysis morphologically characterized RHOA mutated AITL cells as distinct from cells from RHOA mutation negative patients. Computational analysis of single cell morphological parameters revealed that RHOA mutated cells have decreased eccentricity (more circular) compared with RHOA non-mutated AITL cells. In conclusion, the results from the present study expand our understanding of AITL and demonstrate that there are specific cell biological and morphological manifestations of RHOA mutations in cases of AITL.

Molecular/Cytogenetic Education for Hematopathology Fellows

OBJECTIVES

At a discussion on molecular/cytogenetic education for hematopathology fellows at the 2018 Society for Hematopathology Program Directors Meeting, consensus was that fellows should understand basic principles and indications for and limitations of molecular/cytogenetic testing used in routine practice. Fellows should also be adept at integrating results of such testing for rendering a final diagnosis. To aid these consensus goals, representatives from the Society for Hematopathology and the Association for Molecular Pathology formed a working group to devise a molecular/cytogenetic curriculum for hematopathology fellow education.

CURRICULUM SUMMARY

The curriculum includes a primer on cytogenetics and molecular techniques. The bulk of the curriculum reviews the molecular pathology of individual malignant hematologic disorders, with applicable molecular/cytogenetic testing for each and following the 2017 World Health Organization classification of hematologic neoplasms. Benign hematologic disorders and bone marrow failure syndromes are also discussed briefly. Extensive tables are used to summarize genetics of individual disorders and appropriate methodologies.

CONCLUSIONS

This curriculum provides an overview of the current understanding of the molecular biology of hematologic disorders and appropriate ancillary testing for their evaluation. The curriculum may be used by program directors for training hematopathology fellows or by practicing hematopathologists.

Peripheral T cell lymphomas: from the bench to the clinic

Peripheral T cell lymphomas (PTCLs) are a heterogeneous group of orphan neoplasms. Despite the introduction of anthracycline-based chemotherapy protocols, with or without autologous haematopoietic transplantation and a plethora of new agents, the progression-free survival of patients with PTCLs needs to be improved. The rarity of these neoplasms, the limited knowledge of their driving defects and the lack of experimental models have impaired clinical successes. This scenario is now rapidly changing with the discovery of a spectrum of genomic defects that hijack essential signalling pathways and foster T cell transformation. This knowledge has led to new genomic-based stratifications, which are being used to establish objective diagnostic criteria, more effective risk assessment and target-based interventions. The integration of genomic and functional data has provided the basis for targeted therapies and immunological approaches that underlie individual tumour vulnerabilities. Fortunately, novel therapeutic strategies can now be rapidly tested in preclinical models and effectively translated to the clinic by means of well-designed clinical trials. We believe that by combining new targeted agents with immune regulators and chimeric antigen receptor-expressing natural killer and T cells, the overall survival of patients with PTCLs will dramatically increase.

Combination of multicolor flow cytometry for circulating lymphoma cells and tests for the RHOAG17V and IDH2R172 hot-spot mutations in plasma cell-free DNA as liquid biopsy for the diagnosis of angioimmunoblastic T-cell lymphoma

We applied two-step multicolor flow cytometry (FCM) for circulating lymphoma cells in the blood of 20 patients with angioimmunoblastic T-cell lymphoma (AITL) and confirmed neoplastic T-cells in all. Eleven exhibited dim expression of CD3 and 7 lost its expression. The proportion of CD10⁺ lymphoma cells ranged widely from 0 to 100%, with a median of 15.7%. Ten patients demonstrated expansion of a single T-cell receptor β-chain repertoire. Lymphoma cells comprised 0.01 to 18.22% (median, 0.26%) of white cells and the absolute numbers ranged from 0.5 to 1491.6 cells (median, 29.3 cells) per microliter of blood. We next found that 14 (70%) and 3 (15%) patients carried RHOA^G17V and IDH2^R172 mutations, respectively, in cell-free DNA (cfDNA) in the plasma. The combination of multicolor FCM of the blood, and tests for RHOA^G17V and IDH2^R172 hot-spot mutations in plasma cfDNA provides a blood-based 'liquid biopsy' for the diagnosis of AITL.

Application of a 5 Marker Panel to the Routine Diagnosis of Peripheral T-Cell Lymphoma With T-Follicular Helper Phenotype

The 2017 World Health Organization update introduced a new category of nodal peripheral T-cell lymphoma with T-follicular helper phenotype (PTCL-TFH) defined by expression of at least 2 or 3 TFH markers. Our study assesses the utility of an immunohistochemical panel of 5 TFH markers (CD10, BCL6, PD-1, CXCL13, and ICOS) for identification of TFH phenotype in angioimmunoblastic T-cell lymphoma (AITL) and PTCL not otherwise specified (NOS). Immunohistochemical for the 5 markers was performed on 22 cases of AITL and 29 cases of PTCL-NOS. Cases were reviewed for morphologic features characteristic of AITL. All AITL cases showed expression of ≥2 TFH markers. This panel resulted in reclassification of 41% PTCL-NOS cases to PTCL-TFH. Positive percent agreement for the TFH phenotype is 97% for PD1, 94% for ICOS, 44% for CD10 and CXCL13, and 29% for BCL6. Negative percent agreement for TFH phenotype is 100% for CD10, BCL6, and CXCL13, 82% for ICOS and 71% for PD1. AITL cases were more likely than PTCL-TFH cases to contain expanded CD21-positive follicular dendritic cell meshworks, clear cell cytology and polymorphous inflammatory background; however, there was a significant (P<0.005) Kruskal-Wallis trend in all morphologic variables between the 3 groups suggesting a continuum from PTCL-NOS to PTCL-TFH to AITL. The median number of morphologic features of AITL also correlated significantly with number of TFH markers positive (Spearman coefficient ρ=0.759). In summary, the stain panel chosen will have an impact on cases classified as PTCL-TFH. This entity may exist along a spectrum between PTCL-NOS and AITL.

Angioimmunoblastic T-cell lymphoma in Taiwan reveals worse progression-free survival for RHOA G17V mutated subtype

Angioimmunoblastic T-cell lymphoma (AITL) carries genetic mutations of TET2, RHOA, and IDH2, but the prognostic impact of these mutations is not widely investigated. Although one study shows no difference in overall survival between patients with or without RHOA G17V mutation, a poor performance status is associated with RHOA G17V-mutated AITL, which is an independent adverse factor. We retrospectively investigated the prognostic impact of RHOA G17V mutation in AITL patients. A total of 31 cases were enrolled (male-to-female, 2.1; mean age: 62.8 years). RHOA G17V mutation was analyzed by deep sequencing. We found that in contrast to RHOA-wild type, patients with RHOA G17V-mutated AITL more frequently had B symptoms (p = .035), stronger PD1 expression (p = .045), ≥3 TFH markers (p = .011), higher blood vessel density (p<.001), and poorer progression-free survival (p = .046). These results support a role for RHOA genetic testing in AITL patients as ROHA G17V mutation carries a worse prognosis, probably associated with B symptoms and stage IV disease.

EBV status has prognostic implication among young patients with angioimmunoblastic T-cell lymphoma

Epstein‐Barr virus (EBV)‐positive B cells have been detected in 66%‐86% of patients with angioimmunoblastic T‐cell lymphoma (AITL). However, it remains controversial whether EBV status has an impact on the survival of patients with AITL. In this study, we aimed to reevaluate the impact of EBV on the clinicopathological characteristics of AITL. In particular, we focused on the impact of EBV in younger patients with AITL. In total, 270 cases of AITL were studied. Epstein‐Barr virus‐positive B cells were detected in 191 (71%) cases (EBER⁺ group). Among the patients who received anthracycline‐based therapy, the EBER status did not affect the overall survival (OS) or progression‐free survival (PFS). In the younger group of AITL (≤60 years), PFS was significantly worse in the EBER⁻ group compared to the EBER⁺ group (P = .0013). Furthermore, the multivariate analysis identified EBER‐negative status, thrombocytopenia, and elevated serum IgA level as significant adverse prognostic factors for PFS (P < .001, P < .001, and P = .002). Based on these findings, we constructed new prognostic model for the younger group, based on three adverse factors. We classified the patients into two risk groups: low risk (no or 1 adverse factor) and high risk (2 or 3 adverse factors). This new model for younger patients with AITL showed that both OS and PFS were significantly related to the level of risk (P < .0001). In summary, this study showed that, among younger patients with AITL, an EBER⁺ status significantly improved prognosis compared to an EBER⁻ status. Our new prognostic model should be applicable to younger patients with AITL.

Interferon gamma inducible protein 16 (IFI16) expression is reduced in mantle cell lymphoma

IFI16, member of the IFN-inducible PYHIN-200 gene family, modulates proliferation, survival and differentiation of different cell lineages. In particular, IFI16 expression, which is regulated during the differentiation of B cells, was recently studied in B-CLL as well. Here, we compared IFI16 expression in several lymphomas including Burkitt lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, marginal zone lymphoma and mantle cell lymphoma with respect to normal cell counterparts. We observed that IFI16 expression was significantly deregulated only in mantle cell lymphoma (p < 0.05). Notably, IFI16 was associated with the expression of genes involved in interferon response, cell cycle, cell death and proliferation and, interestingly, lipid and glucose metabolism, suggesting that IFI16 deregulation might be associated with relevant changes in cell biology. In our group of mantle cell lymphoma samples a correlation between patient survival and IFI16 expression was not detected even though mantle cell lymphoma prognosis is known to be associated with cell proliferation. Altogether, these results suggest a complex relationship between IFI16 expression and MCL which needs to be analyzed in further studies.

Proliferative, pro-inflammatory, and angiogenesis regulator gene expression profile defines prognosis in different histopathological subtypes of nodal peripheral T-cell lymphoma

Nodal peripheral T-cell lymphoma (PTCL) is an aggressive and heterogeneous malignancy with poor prognosis. We studied the prognostic impact of the expression profile of genes related to cell proliferation (CCNA2, TOP2A, and CHEK1), pro-inflammatory activity (NFkB1 and IKBkB), and angiogenesis (VEGF1) in nodal PTCL outcomes, as well as the ability of this genomic panel to discriminate different histological subtypes. We investigated the relative expression of regulator genes in 63 nodal PTCL patients. CCNA2, TOP2A, CHEK1, and NF-kB1 proteins were also assessed by immunohistochemistry. The median patient age was 47 years, 57.1% were male, 34.9% were diagnosed with PTCL-NOS, 28.6% with ALK-/ALCL, 22.2% with ALK+/ALCL, and 14.3% with AITL. The proliferative genes were associated with worse 3-year OS and PFS in PTCL-NOS and better 3-year PFS in ALK-/ALCL. Expression of CCNA2≥median and overexpression of CHEK1 protein (HR 3.793; p = 0.007) were associated with worse OS for all the cohort of nodal PTCL (HR 1.418; p = 0.001). The genomic expression profile tested in this study was not able to discriminate the different subtypes of nodal PTCL, although it showed a distinct prognostic significance between PTCL-NOS and ALCL-ALK. Overexpression of the CCNA2 gene and CHEK1 protein were associated with poor prognosis in the total nodal PTCL cohort.

Novel Immunotherapies for T Cell Lymphoma and Leukemia

PURPOSE OF REVIEW

Novel immunotherapies such as checkpoint inhibitors, bispecific antibodies, and chimeric antigen receptor T cells are leading to promising responses when treating solid tumors and hematological malignancies. T cell neoplasms include leukemia and lymphomas that are derived from T cells and overall are characterized by poor clinical outcomes. This review describes the rational and preliminary results of immunotherapy for patients with T cell lymphoma and leukemia.

RECENT FINDINGS

For T cell neoplasms, despite significant research effort, only few agents, such as monoclonal antibodies and allogeneic stem cell transplantation, showed some clinical activity. One of the major hurdles to targeting T cell neoplasms is that activation or elimination of T cells, either normal or neoplastic, can cause significant toxicity. A need to develop novel safe and effective immunotherapies for T cell neoplasms exists. In this review, we will discuss the rationale for immunotherapy of T cell leukemia and lymphoma and present the most recent therapeutic approaches.

Integration of transcriptional and mutational data simplifies the stratification of peripheral T-cell lymphoma

The histological diagnosis of peripheral T-cell lymphoma (PTCL) can represent a challenge, particularly in the case of closely related entities such as angioimmunoblastic T-lymphoma (AITL), PTCL-not otherwise specified (PTCL-NOS), and ALK-negative anaplastic large-cell lymphoma (ALCL). Although gene expression profiling and next generations sequencing have been proven to define specific features recurrently associated with distinct entities, genomic-based stratifications have not yet led to definitive diagnostic criteria and/or entered into the routine clinical practice. Herein, to improve the current molecular classification between AITL and PTCL-NOS, we analyzed the transcriptional profiles from 503 PTCLs stratified according to their molecular configuration and integrated them with genomic data of recurrently mutated genes (RHOA ^G17V , TET2, IDH2 ^R172 , and DNMT3A) in 53 cases (39 AITLs and 14 PTCL-NOSs) included in the series. Our analysis unraveled that the mutational status of RHOA ^G17V , TET2, and DNMT3A poorly correlated, individually, with peculiar transcriptional fingerprints. Conversely, in IDH2 ^R172 samples a strong transcriptional signature was identified that could act as a surrogate for mutational status. The integrated analysis of clinical, mutational, and molecular data led to a simplified 19-gene signature that retains high accuracy in differentiating the main nodal PTCL entities. The expression levels of those genes were confirmed in an independent cohort profiled by RNA-sequencing.

The correlation of clinicopathological features and prognosis in extranodal natural killer/T cell lymphoma: a report of 42 cases in the early stage

This study aimed to explore the clinicopathological features and prognostic correlation of extranodal natural killer (NK)/T cell lymphoma (ENKTCL) in the early stage, screen out the prognostic markers of ENKTCL, and to establish the molecular model of ENKTCL prognosis. A retrospective study was conducted in 88 patients from May 1999 to Dec 2013 in Chinese Academy of Medical Sciences Cancer Hospital, who were diagnosed with ENKTCL according to WHO lymphoid hematopoietic tumor classification (published in 2008). The clinical data and paraffin-embedded tissue blocks were collected. The expressions of CD56, MLH1, PDGFRA, VEGF, PD-L1, PD-1, CyclinD1, p53, and Ki-67 were detected by high-throughput tissue microarray and immunohistochemistry (IHC) staining. The relationship between nine protein expressions and the clinicopathological features and prognosis of patients with ENKTCL were analyzed. The survival time of the 42 patients with complete clinical and follow-up data was 0~153 months. The average survival time was 60.1 months. The survival rates of 1 year, 2 years, and 3 year were 85.7%, 78.6%, and 71.4%, respectively. Single factor survival analysis showed that the increase of serum lactate dehydrogenase (LDH ≥ 240UI/L) before treatment was associated with poor prognosis, and there was a significant difference in survival rate (P = 0.006). Different therapy methods were related with prognosis (P = 0.011); in specifically, radiotherapy alone had the best treatment effect, followed by concurrent chemoradiotherapy, and the worst was chemotherapy alone. But, multivariate statistics indicated that the LDH level and the treatment approach were not independent prognostic factors of ENKTCL. There was no statistical difference between epidemiological factors such as gender, age, and other clinicopathological factors including tumor location, B symptoms, β2-microglobulin levels before treatment, and prognosis. Survival analysis of single factor showed that the positive expression of PDGFRA and PD-L1 was, respectively, related to the poor prognosis of patients with ENKTCL (P = 0.040, 0.007). The patients with Ki-67 overexpression (≥ 50%) had a worse prognosis than those with lower expression (< 50%), and the difference of survival rate between the two groups has statistical significance (P = 0.038). The expression of CD56, MLH1, VEGF, PD-1, CyclinD1, and p53 has no effect on survival rate (P > 0.05). Multivariate survival analysis showed that the expression levels of PDGFRA, PD-L1, and Ki-67 were independent factors in the prognosis of patients with ENKTCL. And the positive expressions of these three proteins were risk factors for prognosis of patients with ENKTCL (PDGFRA: P = 0.045, HR = 8.265, 95% CI: 1.050-65.054; PD-L1: P = 0.005, HR = 9.369, 95% CI: 1.950-45.003; Ki-67: P = 0.023, HR = 3.545, 95% CI: 1.187-10.585). The elevation of serum lactate dehydrogenase (LDH ≥ 240UI/L) before treatment and the treatment approach were associated with poor prognosis, which could be used as adjunct indexes to the prognosis. However, they were not independent factors for the prognosis of patients with ENKTCL. The expressions of PDGFRA, PD-L1, and Ki-67 were independent factors in the prognosis of patients with ENKTCL and these three proteins were risk factors of prognosis. The above markers combined with clinical factors may establish the prognosis model of ENKTCL.

Molecular and Genomic Landscape of Peripheral T-Cell Lymphoma

Peripheral T-cell lymphoma (PTCL) is an uncommon group of lymphoma covering a diverse spectrum of entities. Little was known regarding the molecular and genomic landscapes of these diseases until recently but the knowledge is still quite spotty with many rarer types of PTCL remain largely unexplored. In this chapter, the recent findings from gene expression profiling (GEP) studies, including profiling data on microRNA, where available, will be presented with emphasis on the implication on molecular diagnosis, prognostication, and the identification of new entities (PTCL-GATA3 and PTCL-TBX21) in the PTCL-NOS group. Recent studies using next-generation sequencing have unraveled the mutational landscape in a number of PTCL entities leading to a marked improvement in the understanding of their pathogenesis and biology. While many mutations are shared among PTCL entities, the frequency varies and certain mutations are quite unique to a specific entity. For example, TET2 is often mutated but this is particularly frequent (70-80%) in angioimmunoblastic T-cell lymphoma (AITL) and IDH2 R172 mutations appear to be unique for AITL. In general, chromatin modifiers and molecular components in the CD28/T-cell receptor signaling pathways are frequently mutated. The major findings will be summarized in this chapter correlating with GEP data and clinical features where appropriate. The mutational landscape of cutaneous T-cell lymphoma, specifically on mycosis fungoides and Sezary syndrome, will also be discussed.

Tumor Microenvironment in T-Cell Lymphomas

T-cell lymphomas (TCL) are uncommon non-Hodgkin lymphomas that often have an aggressive clinical course. Patients typically have limited treatment options upon relapse and a dismal prognosis after progression despite newly approved therapies. New therapeutic approaches for these orphan diseases are very much needed and a greater understanding of the role of nonmalignant immune cells in the tumor microenvironment may allow for an improved antitumor immune response. The tumor microenvironment is a key component in tumor evasion and typically results in an ineffective T-cell response to the tumor cells despite a significant inflammatory response. A better understanding of the tumor microenvironment therefore, in an effort to overcome the barriers to an effective immune response, would help in developing novel therapeutic approaches to treat and improve outcomes of these diseases. Immune checkpoint blockade to reinvigorate suppressed T-cell, or modulation of the CD47-SIRPalpha axis to promote macrophage phagocytosis, would be such targets. However, whether modulating the immune response using each pathway alone or whether a combination approach is necessary has yet to be determined.

Angioimmunoblastic T-Cell Lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) is one of the most common types of T-cell lymphoma, representing about 15-20% of cases of peripheral T-cell lymphoma (PTCL). It is characterized by a unique clinical presentation and distinct pathologic and molecular features. Classes of drugs particularly active in AITL are emerging; however, treatment of relapsed and refractory disease remains a challenge. This chapter reviews the epidemiology, clinical presentation, pathogenesis, diagnosis, and treatment of AITL.