Angioimmunoblastic T-cell lymphoma is the most common T-cell lymphoma in two distinct French information data sets

Hematological Oncology journal women in lymphoma special issue: Latest updates in nodal peripheral T-cell lymphoma

In the last decade, there has been increased understanding of the pathologic features and biology of peripheral T cell lymphomas (PTCLs) through development of multi omics and molecular profiling techniques. In addition, international collaborations through multi center trials as well as prospective registry studies have improved our knowledge of host and tumor genomic factors and treatment factors affecting disease outcomes. In our review today, we aim to highlight the current epidemiology, latest advances in classification, disease biology and the evolving treatment landscape for nodal PTCLs.

Correlation of low numbers of intratumoral FOXP3+ cells with worse progression-free survival in angioimmunoblastic T cell lymphoma

AIMS

Angioimmunoblastic T cell lymphoma (AITL) is a T cell lymphoma with aberrant immune activity. It is characterised by inflammatory and immune reactions. However, the impact of regulatory T (Treg) cells on AITL remains unclear.

METHODS

We retrospectively collected 46 AITL cases and performed immunohistochemical analysis of forkhead box P3 (FOXP3) expression. The number of immunostained FOXP3 cells was determined using a digital pathology system with whole-slide imaging. The average number of FOXP3+ cells per high-power field (HPF) was determined by randomly counting 20 HPFs. AITL cases were categorised into high-expression and low-expression groups based on the median count of FOXP3+ cells in all analysed samples. The relationship between FOXP3 expression and clinicopathological features was assessed.

RESULTS

Among the studied patients, 14 (30.4%) were females and 32 (69.6%) were males, and the median age at diagnosis was 64.1 years. The median expression of FOXP3 was 84.9 positive cells/HPF. FOXP3 expression negatively correlated with Epstein-Barr virus-encoded small RNA positivity in tumour (p=0.041). The patients with low FOXP3 expression presented with aggressive clinical behaviour, including advance-staged diseases (p=0.043), splenomegaly (p=0.008), B symptoms (p=0.019) and extranodal involvement (p=0.019). The neutrophil-to-lymphocyte ratio was higher in the patients with low FOXP3 expression, compared with those with high FOXP3 expression. Low FOXP3 expression had an adverse effect on progression-free survival (PFS, p=0.033), and increased the risk of recurrence 2.320-fold (HR 2.320 (95% CI 1.109 to 4.856); p=0.025).

CONCLUSIONS

Patients with AITL with low FOXP3 expression tend to have aggressive clinical presentation and shortened PFS. These findings may help with risk stratification and determination of new treatment strategy.

In vivo CAR T cell therapy against angioimmunoblastic T cell lymphoma

BACKGROUND

For angioimmunoblastic T cell lymphoma (AITL), a rare cancer, no specific treatments are available and survival outcome is poor. We previously developed a murine model for AITL that mimics closely human disease and allows to evaluate new treatments. As in human AITL, the murine CD4+ follicular helper T (Tfh) cells are drivers of the malignancy. Therefore, chimeric antigen receptor (CAR) T cell therapy might represent a new therapeutic option.

METHODS

To prevent fratricide among CAR T cells when delivering an CD4-specific CAR, we used a lentiviral vector (LV) encoding an anti-CD4 CAR, allowing exclusive entry into CD8 T cells.

RESULTS

These anti-CD4CAR CD8-targeted LVs achieved in murine AITL biopsies high CAR-expression levels in CD8 T cells. Malignant CD4 Tfh cells were eliminated from the mAITL lymphoma, while the CAR + CD8 T cells expanded upon encounter with the CD4 receptor and were shaped into functional cytotoxic cells. Finally, in vivo injection of the CAR + CD8-LVs into our preclinical AITL mouse model carrying lymphomas, significantly prolonged mice survival. Moreover, the in vivo generated functional CAR + CD8 T cells efficiently reduced neoplastic T cell numbers in the mAITL tumors.

CONCLUSION

This is the first description of in vivo generated CAR T cells for therapy of a T cell lymphoma. The strategy described offers a new therapeutic concept for patients suffering from CD4-driven T cell lymphomas.

Phase 2 trial of the farnesyltransferase inhibitor tipifarnib for relapsed/refractory peripheral T-cell lymphoma

ABSTRACT

A phase 2, international, open-label, nonrandomized, single-arm trial was conducted to evaluate the efficacy and safety of tipifarnib, a farnesyltransferase inhibitor, as monotherapy for relapsed/refractory peripheral T-cell lymphoma (PTCL) and to evaluate tumor mutation profile as a biomarker of response. Adults with relapsed/refractory PTCL received tipifarnib 300 mg orally twice daily for 21 days in a 28-day cycle. The primary end point was objective response rate (ORR); secondary end points included ORR, progression-free survival (PFS), duration of response (DOR), and adverse events (AEs) in specific subtypes. Sixty-five patients with PTCL were enrolled: n = 38 angioimmunoblastic T-cell lymphoma (AITL), n = 25 PTCL not otherwise specified, and n = 2 other T-cell lymphomas. The ORR was 39.7% (95% confidence interval [CI], 28.1-52.5) in all patients and 56.3% (95% CI, 39.3-71.8) for AITL. Median PFS was 3.5 months overall (954% CI, 2.1-4.4), and 3.6 months (95% CI, 1.9-8.3) for AITL. Median DOR was 3.7 months (95% CI, 2.0-15.3), and greatest in patients with AITL (7.8 months; 95% CI, 2.0-16.3). The median overall survival was 32.8 months (95% CI, 14.4 to not applicable). Tipifarnib-related hematologic AEs were manageable and included neutropenia (43.1%), thrombocytopenia (36.9%), and anemia (30.8%); other tipifarnib-related AEs included nausea (29.2%) and diarrhea (27.7%). One treatment-related death occurred. Mutations in RhoA, DNMT3A, and IDH2 were seen in 60%, 33%, and 27%, respectively, in the AITL tipifarnib responder group vs 36%, 9%, and 9% in the nonresponder group. Tipifarnib monotherapy demonstrated encouraging clinical activity in heavily pretreated relapsed/refractory PTCL, especially in AITL, with a manageable safety profile. This trial was registered at www.ClinicalTrials.gov as #NCT02464228.

Follicular helper T cells: emerging roles in lymphomagenesis

Follicular helper T cells are a subset of CD4+ T cells that are fundamental to forming germinal centers, which are the primary sites of antibody affinity maturation and the proliferation of activated B cells. Follicular helper T cells have been extensively studied over the past 10 years, especially regarding their roles in cancer genesis. This review describes the characteristics of normal follicular helper T cells and focuses on the emerging link between follicular helper T cells and lymphomagenesis. Advances in lymphoma genetics have substantially expanded our understanding of the role of follicular helper T cells in lymphomagenesis. Moreover, we detail a range of agents and new therapies, with a major focus on chimeric antigen receptor T-cell therapy; these novel approaches may offer new treatment opportunities for patients with lymphomas.

What is new in the 5th edition of the World Health Organization classification of mature B and T/NK cell tumors and stromal neoplasms?

The classification of tumors is essential in the diagnosis and clinical management of patients with malignant neoplasms. The World Health Organization (WHO) provides a globally applicable classification scheme of neoplasms and it was updated several times. In this review, we briefly outline the cornerstones of the upcoming 5th edition of the World Health Organization Classification of Haematolymphoid Tumours on lymphoid neoplasms. As is adopted throughout the 5th edition of the WHO classification of tumors of all organ systems, entities are listed by a hierarchical system. For the first time, tumor-like lesions have been included in the classification, and modifications of nomenclature for some entities, revisions of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities are presented along with mesenchymal lesions specific to the stroma of lymph nodes and the spleen. In addition to specific outlines on constitutional and somatic genetic changes associated with given entities, a separate chapter on germline predisposition syndromes related to hematologic neoplasms has been added.

Incidence trends for common subtypes of T-cell lymphoma in Taiwan and the United States from 2008-2020

The incidence of T-cell lymphoma (TCL) has been continually increasing in Taiwan and the United States (US) in recent years. This epidemiological study using population-based registry data aimed to determine the incidence patterns of common subtypes of TCL in Taiwan from 2008-2020 and compare them with those in the US and the Asian/Pacific Islander (API) population. Subtypes included angioimmunoblastic T-cell lymphoma (AITL); extranodal NK/T-cell lymphoma, nasal or other type (ENKTL); peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS); and anaplastic large cell lymphoma (ALCL). The total number of patients newly diagnosed with TCL during 2008-2020 was 4477, 3171, and 48,889 in Taiwan, API, and the US, respectively. Except the incidence rate of AITL in Taiwan, the incidence rates of these common TCL subtypes showed downward trends in all studied populations. There was also a significant increase in the relative frequency of AITL among TCL in Taiwan, with an annual percent change of 4.44 (p < 0.001), from 8.44% in 2002 to 20.63% in 2020. The rapid development of diagnostics may be the main factor contributing to this rise in incidence.

Oral azacitidine compared with standard therapy in patients with relapsed or refractory follicular helper T-cell lymphoma (ORACLE): an open-label randomised, phase 3 study

BACKGROUND

Follicular helper T-cell lymphomas (TFHL) harbour frequent alterations in genes that regulate DNA methylation. Preliminary reports suggest that treatment with 5-azacitidine has clinical activity in patients with relapsed or refractory TFHL. We aimed to compare the oral form of azacitidine with investigator's choice standard therapy (ICT; ie, gemcitabine, bendamustine, or romidepsin) in patients with relapsed or refractory TFHL.

METHODS

Patients older than 18 years with relapsed or refractory TFHL (angioimmunoblastic T-cell lymphoma, follicular lymphoma, or nodal T-cell lymphoma with phenotype, ie, positive with two or more markers among CD10, BCL6, CXCL13, PD1, or ICOS) based on the 2017 WHO classification of haematological neoplasms, with an Eastern Cooperative Oncology Group performance status score of 0-3, were recruited in university hospitals from five European countries and from Japan. Patients were randomly assigned 1:1 to treatment with either azacitidine given at a dose of 300 mg once a day (200 mg in Japanese patients) for 14 days in a 28-day cycle or gemcitabine, bendamustine, or romidepsin according to the investigator's choice. Random assignment was stratified by the number of previous lines of therapy and by the presence of previous or concomitant myeloid malignancy. The primary endpoint was investigator-assessed progression-free survival, presented in the intention-to-treat population. This Article is the final analysis of this trial, registered at ClinicalTrials.gov (Europe NCT03593018 and Japan NCT03703375).

FINDINGS

86 patients (median age 69 years [IQR 62-76], 50 patients were male, 36 were female) were enrolled between Nov 9, 2018, to Feb 22, 2021; 42 in the azacitidine group and 44 in the ICT group. With a median follow-up of 27·4 months (IQR 20·2-32·9), the median progression-free survival was 5·6 months (95% CI 2·7 -8·1) in the azacitidine group versus 2·8 months (1·9-4·8) in the ICT group (hazard ratio of 0·63 (95% CI 0·38-1·07); 1-sided p=0·042). Grade 3-4 adverse events were reported in 32 (76%) of 42 patients in the azacitidine group versus 42 (98%) of 43 patients in the ICT group. The most adverse grade 3 or worse adverse events were haematological (28 [67%] of 42 patients vs 40 [93%] of 43 patients), infection (8 [19%] and 14 [33%]), and gastrointestinal (5 [12%] vs 1 [2%] for azacitidine and ICT, respectively). There were two treatment-related deaths in the azacitidine group (one endocarditis and one candidiasis) and three in the ICT group (one heart failure, one COVID-19, and one cause unknown).

INTERPRETATION

Although the pre-specified primary outcome of the trial was not met, the favourable safety profile suggests that azacitidine could add to the treatment options in these difficult to treat diseases especially in combination with other drugs. Trials with combination are in preparation in a platform trial.

FUNDING

Bristol-Myers Squibb.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

A Case Report on a Rare Type of Lymphoma: Angioimmunoblastic T-cell Lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) is a rare type of non-Hodgkin lymphoma (NHL). We present a case of a 60-year-old female who attended the emergency department (ED) with fatigue, recurrent fever, weight loss, and adenopathy for six months. Laboratory findings showed anemia, lymphocytosis, eosinophilia, thrombocytosis, cholestasis, hypoproteinemia, and hypoalbuminemia. Abdominopelvic computed tomography (CT) revealed multiple adenopathies. A lymph node biopsy yielded inconclusive results in the outpatient clinic. Later, during admission, the patient underwent a positron emission tomography-computed tomography (PET-CT), revealing a cervical adenopathy cluster that was excised en bloc. Histology confirmed the diagnosis of AITL. The medical team initiated chemotherapy but opted for exclusive symptomatic treatment due to disease progression. The patient died six months after diagnosis. The fluctuating and nonspecific presentation of AITL can hinder and delay definitive diagnosis, therefore impacting treatment and prognosis.

Diagnosis of bone marrow involvement in angioimmunoblastic T-cell lymphoma should be based on both [18F]FDG-PET/CT and bone marrow biopsy findings

OBJECTIVE

During the initial staging of certain lymphoma subtypes, 18 F-fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) has become an alternative to bone marrow biopsy (BMB) for detecting bone marrow (BM) involvement. However, whether [18F]FDG-PET/CT can accurately detect BM involvement in angioimmunoblastic T-cell lymphoma (AITL) remains unknown. Our study aimed to assess the diagnostic and prognostic capability of [18F]FDG-PET/CT for detecting BM involvement in AITL. Methods: This retrospective study included 84 individuals newly diagnosed with AITL who underwent baseline BMB and [18F]FDG-PET/CT. "BM involvement" was defined as one or both of the following: 1) angioimmunoblastic T-cells detected in the BM; or 2) initially heightened focal uptake having disappeared on follow-up [18F]FDG-PET/CT. The ability of [18F]FDG-PET/CT to detect BM cancerous lesions was respectively analyzed by BM involvement confirmed by BMB or the aforementioned definition as the reference standard. The patients' clinical characteristics and survival and prognostic outcomes were respectively analyzed.

RESULTS

Of the 84 participants, five (6.0%) displayed positive BMB and PET/BM results, 17 (20.2%) had BMB-positive but PET/BM-negative results, eight (9.5%) showed BMB-negative but PET/BM-positive outcomes, and 54 (64.3%) displayed negative BMB and PET/BM outcomes. Using pre-defined BM involvement as the reference standard, [18F]FDG-PET/CT exhibited a specificity of 100%, sensitivity of 40%, negative predictive value (NPV) of 75%, and positive predictive value (PPV) of 100%. In contrast, using BMB-detected BM involvement as reference, [18F]FDG-PET/CT exhibited a sensitivity, specificity, PPV, and NPV of 38.5%, 76.1%, 22.7%, and 87.1%, respectively. Among patients with PET/BM-positive and BMB-negative outcomes, 62.5% (5/8) underwent upstaging from III to IV. In 58.8% (10/17) of patients who were initially diagnosed with stage II/III disease based on the [18F]FDG-PET/CT results, repeat BMB resulted in upstaging to IV. PET/BM-negative patients had a higher 3-year progression-free survival rate (38.3% vs. 22.8%, p = 0.018) and 3-year overall survival rate (64.4% vs. 34.6%, p = 0.011) than PET/BM-positive patients.

CONCLUSION

In AITL patients, PET/BM-positive results may obviate the necessity for repeat BMB to ascertain confirm BM involvement. PET/BM-negative results do not definitively exclude BM involvement. The combined use of [18F]FDG-PET/CT and BMB can increase the diagnostic accuracy of BM involvement for AITL patients.

Outcome of combined modality treatment in first-line for stage I(E) peripheral T-cell lymphoma; a nationwide population-based cohort study from the Netherlands

Peripheral T-cell lymphomas (PTCL) comprise a heterogeneous group of mature T-cell neoplasms with an unfavorable prognosis; presentation with stage I(E) disease is uncommon. In clinical practice, an abbreviated chemotherapy treatment regimen combined with radiotherapy (combined modality treatment [CMT]) is commonly used, although evidence from clinical trials is lacking. The aim of this nationwide population-based cohort study is to describe first-line treatment and outcome of patients with stage I(E) PTCL. All newly diagnosed patients ≥18 years with stage I(E) anaplastic large cell lymphoma (ALCL), angioimmunoblastic T-cell lymphoma (AITL) and peripheral T-cell lymphoma NOS (PTCL not otherise specified [NOS]) in 1989-2020 were identified in the Netherlands Cancer Registry. Patients were categorized according to treatment regimen, i.e., chemotherapy (CT), radiotherapy (RT), CMT, other therapy and no treatment. The primary endpoint was overall survival (OS). Patients with stage I(E) ALCL, AITL and PTCL NOS (n=576) were most commonly treated with CMT (28%) or CT (29%), 2% underwent SCT. RT only was given in 18%, and 8% received other therapy and 16% no treatment. Overall, the 5-year OS was 59%. According to subtype, 5-year OS was superior for ALCL as compared to PTCL NOS and AITL (68% vs. 55% and 52%, respectively; P=0.03). For patients treated with CMT, 5-year OS was significantly higher (72%) as compared to patients treated with either CT or RT alone (55% and 55%, respectively; P<0.01). In multivariable analysis, age per year increment (hazard ratio [HR] =1.06, 95% confidence interval [CI]: 1.05-1.07), male sex (HR=1.53, 95% CI: 1.23-1.90), and CT, or no treatment (HR=1.64, 95% CI: 1.21-2.21, and HR=1.55, 95% CI: 1.10-2.17, respectively) were associated with a higher risk of mortality. For stage I(E) ALCL, AITL and PTCL NOS, 5-year OS is 59%, comparing favorably to historical outcome in advanced-stage disease. Superior outcome estimates were observed in patients treated with CMT.

The 5th edition of the World Health Organization Classification of mature lymphoid and stromal tumors - an overview and update

The purpose of this review is to give an overview on the conceptual framework and major developments of the upcoming 5th edition of the World Health Organization (WHO) Classification of Haematolymphoid tumours (WHO-HAEM5) and to highlight the most significant changes made in WHO-HAEM5 compared with the revised 4th edition (WHO-HAEM4R) of lymphoid and stromal neoplasms. The changes from the revised 4th edition include the reorganization of entities by means of a hierarchical system that is realized throughout the 5th edition of the WHO classification of tumors of all organ systems, a modification of nomenclature for some entities, the refinement of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities. For the first time, tumor-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms are included in the classification.

SOHO State-of-the-Art Updates and Next Questions: Treatment for Newly Diagnosed Peripheral T-Cell Lymphomas

Although a rare subset of non-Hodgkin lymphomas, peripheral T-cell lymphomas (PTCL) account for a disproportionate proportion of patient mortality. Conventional therapies are derived from experience treating aggressive B-cell lymphomas and center around CHOP-based chemotherapy. However, due to the unique biology and diverse subtypes of PTCL, most patients fail to durably respond to this approach and 5-year survival is only 20% to 30%. There have been multiple attempts to improve outcomes for patients with PTCL. Among the more successful strategies are the use of consolidative autologous stem cell transplant, the augmentation of CHOP with etoposide (CHOEP), and the use of brentuximab vedotin in CD30-positive PTCL. Advances in the understanding of histology-specific biology has cultivated enthusiasm to evaluate hypomethylating agents, histone deacetylate inhibitors, and phosphoinositol-3-kinase inhibitors in the frontline setting. Improvements in monitoring disease response and prognostication including the use of cell-free DNA, mutational profiling, and interim PET/CT imaging are also on the horizon. For patients with acute T-cell leukemia/lymphoma, the use of mogamulizumab-based therapy in the frontline setting may lead to advances in care. The true impact of these new-era therapies will only be elucidated as clinical practices incorporate the rapidly changing evidence.

Angioimmunoblastic T-cell lymphoma and Kaposi sarcoma: A fortuitous collision?

AIMS

Follicular helper T-cell (TFH) lymphoma of the angioimmunoblastic-type (AITL), one of the most prevalent T-cell lymphomas, typically encompasses proliferation of high endothelial venules and Epstein-Barr virus-positive immunoblasts, but neither infection with HHV8 nor association with Kaposi's sarcoma (KS) have been described. The aims of this study are to characterise the association between AITL and HHV8 infection or KS.

METHODS AND RESULTS

Three male patients aged 49-76 years, HIV-negative, with concurrent nodal involvement by AITL and KS, were identified from our files and carefully studied. Two patients originated from countries where endemic KS occurs, including one with cutaneous KS. The lymphomas featured abundant vessels, expanded follicular dendritic cells and neoplastic TFH cells [PD1+ (three of three), ICOS+ (three of three), CXCL13+ (three of three), CD10+ (two of three), BCL6 (two of three)] but lacked EBV+ immunoblasts. The foci of KS consisted of subcapsular proliferations of ERG+, CD31+ and/or CD34+ , HHV8+ spindle cells. High-throughput sequencing showed AITL-associated mutations in TET2 (three of three), RHOA (G17V) (three of three) and IDH2 (R172) (two of three), which were absent in the microdissected KS component in two cases. Relapses in two patients consisted of AITL, without evidence of KS. No evidence of HHV8 infection was found in a control group of 23 AITL cases.

CONCLUSION

Concurrent nodal involvement by AITL and KS is rare and identification of both neoplastic components may pose diagnostic challenges. The question of whether the association between AITL and KS may be fortuitous or could reflect the underlying immune dysfunction in AITL remains open.

Pathobiology of nodal peripheral T-cell lymphomas: current understanding and future directions

Predominantly nodal is the most common clinical presentation of peripheral T- (and NK-) cell lymphomas (PTCL), which comprise three main groups of diseases: (i) systemic anaplastic large cell lymphomas (ALCL), whether positive or negative for anaplastic lymphoma kinase (ALK); (ii) follicular helper T-cell lymphomas (TFHL); and (iii) PTCL, not otherwise specified (NOS). Recent advances in the genomic and molecular characterization of PTCL, with enhanced understanding of pathobiology, have translated into significant updates in the latest 2022 classifications of lymphomas. ALK-negative ALCL is now recognized to be genetically heterogeneous, with identification of DUSP22 rearrangements in approximately 20-30% of cases, correlated with distinctive pathological and biological features. The notion of cell-of-origin as an important determinant of the classification of nodal PTCL is best exemplified by TFHL, considered as one disease or a group of related entities, sharing oncogenic pathways with frequent recurrent epigenetic mutations as well as a relationship to clonal hematopoiesis. Data are emerging to support that a similar cell-of-origin concept might be relevant to characterize meaningful subgroups within PTCL, NOS, based on cytotoxic and/or Th1 versus Th2 signatures. The small group of primary nodal Epstein-Barr virus-positive lymphomas of T- or NK-cell derivation, formerly considered PTCL, NOS, is now classified separately, due to distinctive features, and notably an aggressive course. This review summarizes current knowledge of the pathology and biology of nodal-based PTCL entities, with an emphasis on recent findings and underlying oncogenic mechanisms.

Advances in the pathogenesis and therapeutic strategies of angioimmunoblastic T-cell lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) is an aggressive subtype of peripheral T-cell lymphomas with its cell origin determined to be follicular helper T-cells. AITL is characterized by a prominent tumor microenvironment involving dysregulation of immune cells, signaling pathways, and extracellular matrix. Significant progress has been made in the molecular pathophysiology of AITL, including genetic mutations, immune metabolism, hematopoietic-derived microenvironment, and non-hematopoietic microenvironment cells. Early diagnosis, detection of severe complications, and timely effective treatment are crucial for managing AITL. Treatment typically involves various combination chemotherapies, but the prognosis is often poor, and relapsed and refractory AITL remains challenging, necessitating improved treatment strategies. Therefore, this article provides an overview of the pathogenesis and latest advances in the treatment of AITL, with a focus on potential therapeutic targets, novel treatment strategies, and emerging immunotherapeutic approaches.

The implication of next-generation sequencing in the diagnosis and clinical management of non-Hodgkin lymphomas

Next generation sequencing (NGS) is a technology that broadens the horizon of knowledge of several somatic pathologies, especially in oncological and oncohematological pathology. In the case of NHL, the understanding of the mechanisms of tumorigenesis, tumor proliferation and the identification of genetic markers specific to different lymphoma subtypes led to more accurate classification and diagnosis. Similarly, the data obtained through NGS allowed the identification of recurrent somatic mutations that can serve as therapeutic targets that can be inhibited and thus reducing the rate of resistant cases. The article's purpose is to offer a comprehensive overview of the best ways of integrating of next-generation sequencing technologies for diagnosis, prognosis, classification, and selection of optimal therapy from the perspective of tailor-made medicine.

Clinical features and prognostic outcomes of angioimmunoblastic T cell lymphoma in an Asian multicenter study

In our Asian multicenter retrospective study, we investigated the clinical prognostic factors affecting the outcomes of AITL patients and identified a novel prognostic index relevant in the Asian context. In our 174-patient cohort, the median PFS and OS was 1.8 years and 5.6 years respectively. Age > 60, bone marrow involvement, total white cell count >12 × 109/L and raised serum lactate dehydrogenase were associated with poorer PFS and OS in multivariate analyses. This allowed for a prognostic index (AITL-PI) differentiating patients into low (0-1 factors, n = 64), moderate (2 factors, n = 59) and high-risk (3-4 factors, n = 49) subgroups with 5-year OS of 84.0%, 44.0% and 28.0% respectively (p < 0.0001). POD24 proved to be strongly prognostic (5-year OS 24% vs 89%, p < 0.0001). Exploratory gene expression studies were performed and disparate immune cell profiles and cell signaling signatures were seen in the low risk group as compared to the intermediate and high risk groups.

Salvage therapy with brentuximab-vedotin and bendamustine for patients with R/R PTCL: a retrospective study from the LYSA group

Patients with relapsed or refractory (R/R) peripheral T-cell lymphomas (PTCL) have a poor prognosis. Bendamustine (B) and brentuximab-vedotin (Bv) have shown interesting results in this setting. However, little information is available about their efficacy in combination. This multicenter and retrospective study aimed to evaluate the efficacy and safety of the combination of BBv in patients with noncutaneous R/R PTCL among 21 LYSA centers in France and Belgium. The primary objective was the overall response rate. A total of 82 patients with R/R PTCL were included. The best overall response rate (ORR) was 68%, with 49% of patients in complete response (CR). In multivariable analysis, only the disease status after the last regimen (relapse vs refractory) was associated with the response with an ORR of 83% vs 57%. Median duration of response was 15.4 months for patients in CR. With a median follow-up of 22 months, the median progression free survival (PFS) and overall survival (OS) were 8.3 and 26.3 months respectively. Moreover, patients in CR, who underwent an allogeneic transplant, had a better outcome than patients who did not with a median PFS and OS of 19.3 vs 4.8 months and not reached vs 12.4 months, respectively. Fifty-nine percent of patients experienced grade 3/4 adverse events that were mainly hematologic. BBv is highly active in patients with R/R PTCL and should be considered as a one of the best options of immunochemotherapy salvage combination in this setting and particularly as a bridge to allogeneic transplant for eligible patients.

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.

Angioimmunoblastic T-cell lymphoma and correlated neoplasms with T-cell follicular helper phenotype: from molecular mechanisms to therapeutic advances

Angioimmunoblastic T-cell lymphoma (AITL) is the second most frequent subtype of mature T-cell lymphoma (MTCL) in the Western world. It derives from the monoclonal proliferation of T-follicular helper (TFH) cells and is characterized by an exacerbated inflammatory response and immune dysregulation, with predisposition to autoimmunity phenomena and recurrent infections. Its genesis is based on a multistep integrative model, where age-related and initiator mutations involve epigenetic regulatory genes, such as TET-2 and DNMT3A. Subsequently, driver-mutations, such as RhoA G17V and IDH-2 R172K/S promote the expansion of clonal TFH-cells ("second-hit"), that finally begin to secrete cytokines and chemokines, such as IL-6, IL-21, CXCL-13 and VEGF, modulating a network of complex relationships between TFH-cells and a defective tumor microenvironment (TME), characterized by expansion of follicular dendritic cells (FDC), vessels and EBV-positive immunoblasts. This unique pathogenesis leads to peculiar clinical manifestations, generating the so-called "immunodysplastic syndrome", typical of AITL. Its differential diagnosis is broad, involving viral infections, collagenosis and adverse drug reactions, which led many authors to use the term "many-faced lymphoma" when referring to AITL. Although great advances in its biological knowledge have been obtained in the last two decades, its treatment is still an unmet medical need, with highly reserved clinical outcomes. Outside the setting of clinical trials, AITL patients are still treated with multidrug therapy based on anthracyclines (CHOP-like), followed by up-front consolidation with autologous stem cell transplantation (ASCT). In this setting, the estimated 5-year overall survival (OS) is around 30-40%. New drugs, such as hypomethylating agents (HMAs) and histone deacetylase inhibitors (HDAi), have been used for relapsed/refractory (R/R) disease with promising results. Such agents have their use based on a biological rationale, have significant potential to improve the outcomes of patients with AITL and may represent a paradigm shift in the therapeutic approach to this lymphoma in the near future.

Follicular Helper T-Cell-derived Nodal Lymphomas: Study of Histomorphologic, Immunophenotypic, Clinical, and RHOA G17V Mutational Profile

The study was designed to review the demographic, clinical, and pathologic characteristics of follicular helper T cells (TFH)-derived nodal PTCL in India including angioimmunoblastic T-cell lymphoma (AITL), peripheral T-cell lymphoma (PTCL) with follicular helper T cell phenotype (P-TFH), and follicular T-cell lymphoma with additional immunohistochemistry (IHC) and RHOAG17V mutational analysis, as well as their impact on survival. This retrospective study included 88 cases of PTCL that were reclassified using IHC for TFH markers (PD1, ICOS, BCL6, and CD10) and dendritic-meshwork markers (CD21, CD23). Cases of TFH cell origin were evaluated for RHOAG17V mutation using Sanger sequencing and amplification-refractory mutation system-polymerase chain reaction (PCR) (validated using cloning and quantitative PCR) with detailed clinicopathologic correlation. Extensive re-evaluation with added IHC panel resulted in a total of 19 cases being reclassified, and the final subtypes were AITL (37 cases, 42%), PTCL-not otherwise specified (44, 50%), P-TFH (6, 7%), and follicular T-cell lymphoma (1, 1%). The presence of at least 2 TFH markers (>20% immunopositivity) determined the TFH origin. AITL patients tended to be male and showed increased presence of B-symptoms and hepatosplenomegaly. Histomorphology revealed that 92% of AITL cases had pattern 3 involvement. Sanger sequencing with conventional PCR did not yield any mutation, while RHOAG17V was detected by amplification-refractory mutation system-PCR in AITL (51%, P =0.027) and P-TFH (17%), which was validated with cloning followed by sequencing. Cases of RHOAG17V-mutant AITL had a worse Eastern Cooperative Oncology Group performance status initially but fared better in terms of overall outcome ( P =0.029). Although not specific for AITL, RHOAG17V mutation shows an association with diagnosis and requires sensitive methods for detection due to low-tumor burden. The mutant status of AITL could have prognostic implications and translational relevance.

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.

IDH2 and TET2 mutations synergize to modulate T Follicular Helper cell functional interaction with the AITL microenvironment

Angioimmunoblastic T cell lymphoma (AITL) is a peripheral T cell lymphoma that originates from T follicular helper (Tfh) cells and exhibits a prominent tumor microenvironment (TME). IDH2 and TET2 mutations co-occur frequently in AITL, but their contribution to tumorigenesis is poorly understood. We developed an AITL mouse model that is driven by Idh2 and Tet2 mutations. Malignant Tfh cells display aberrant transcriptomic and epigenetic programs that impair TCR signaling. Neoplastic Tfh cells bearing combined Idh2 and Tet2 mutations show altered cross-talk with germinal center B cells that promotes B cell clonal expansion while decreasing Fas-FasL interaction and reducing B cell apoptosis. The plasma cell count and angiogenesis are also increased in the Idh2-mutated tumors, implying a major relationship between Idh2 mutation and the characteristic AITL TME. Our mouse model recapitulates several features of human IDH2-mutated AITL and provides a rationale for exploring therapeutic targeting of Tfh-TME cross-talk for AITL patients.

Clinicopathologic characteristics, outcomes, and prognostic factors of angioimmunoblastic T-cell lymphoma in China

BACKGROUND

This study aimed to better characterize the clinicopathologic characteristics, outcomes, and prognostic factors of AITL in China.

METHODS

We retrospectively analyzed 312 patients with AITL enrolled between January 2011 and December 2020 from five institutions in China.

RESULTS

The median age was 65 years, with 92.6% advanced stage, 59.7% elevated LDH, 46.1% anemia, and 44.0% hypergammaglobulinemia. The majority of patients (84.9%) received anthracycline-based regimens with or without etoposide, and only 6.1% underwent autologous stem cell transplantation following first remission. The 5-year OS and PFS estimates were 43.4% and 25.0% with no significant improvement of survival between patients treated during 2011-2015 and 2016-2020, respectively. Both the International Prognostic Index (IPI) and the prognostic index for PTCL, not otherwise specified (PIT), were predictive for OS. In multivariate analysis, age >70 years, elevated LDH, and albumin level <35 g/L were independent prognostic factors for OS. Combining these three factors, a novel prognostic model (the Chinese AITL score) was constructed, which stratified patients into low-, intermediate-, and high-risk groups, with 5-year OS rates of 69.0%, 41.5%, and 23.7%, respectively. This new model was successfully validated in an independent cohort.

CONCLUSIONS

Patients with AITL were mainly treated with anthracycline-based regimens, and the outcomes were still unsatisfactory in China. Our novel prognostic model may improve our ability to identify patients at different risks for alternative therapies.

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.

Generalized Cutaneous Nodules on the Trunk and Extremities

A 61-year-old man presented with rapidly growing and itchy cutaneous nodules all over his body and prominent lymphadenopathies. What is your diagnosis?

Incidence, Survival Outcome, and Prognostic Nomogram of Patients with Angioimmunoblastic T-cell Lymphoma: a Population-based Analysis

OBJECTIVE

Due to the rarity of angioimmunoblastic T-cell lymphoma (AITL), very limited data concerning its incidence patterns and prognostic factors are available. This study aimed to explore the incidence, characteristics, survival outcomes, and prognostic factors of AITL.

METHODS

Age-adjusted incidence and temporal trends were calculated based on 1247 AITL patients from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER)-13 database. A total of 1525 AITL patients from the SEER-18 database and 43 patients from our single center were included for survival analysis and nomogram construction.

RESULTS

The age-adjusted incidence for overall cohort was 0.123 [95% confidence interval (CI), 0.117-0.131) per 100 000 during 1992-2017. The overall incidence increased steeply at the rate of 15.3% (95%CI 11.0%-19.8%, P<0.001) per year during 1992-2004, but remained stable during 2004-2017 (P=0.200). Similar incidence trends were observed in age, sex, and stage subgroups. The final nomograms consisted of four variables: age at diagnosis, sex, Ann Arbor stage, and primary site. The concordance index (C-index) of the nomogram for 5-year overall survival prediction was 0.717, 0.690 and 0.820 in the training cohort, validation cohort-1 and cohort-2, respectively. Regarding the disease-specific survival (DSS), the nomogram also demonstrated a good discrimination level, with the C-index for predicting the probability of DSS at 5 years of 0.716, 0.682 and 0.813 for the three cohorts, respectively. The calibration displayed good concordance between the nomogram-predicted and actual observed outcomes.

CONCLUSION

The age-adjusted incidence for AITL was low during 1992-2017. The incidence continuously increased during 1992-2004, but remained stable during 2004-2017. The nomograms as proposed may provide a favorable and accurate prognostic survival prediction 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.

Management of Peripheral T-cell Lymphomas and the Role of Transplant

PURPOSE OF REVIEW

Here, we review the management of peripheral T-cell lymphoma, particularly focusing on the role of autologous and allogeneic stem cell transplant.

RECENT FINDINGS

Peripheral T-cell lymphomas are a rare subset of non-Hodgkin's lymphomas that are treated with curative intent. While therapy has been based on other aggressive lymphoid malignancies, outcomes are generally poorer than B-cell lymphomas with 5-year overall and progression-free survival of 30-40% and 20-30%, respectively. In effort to improve outcomes, transplant has been used in both the frontline and salvage settings. Although not studied in randomized studies, consolidation with autologous stem cell transplant in first remission has been associated with an approximate 5-year overall survival of 50-60% and 5-year progression-free survival of 40-45%. Unfortunately, most patients relapse, and, in this setting, allogeneic transplant remains the only curative option for those who are transplant-eligible. Multiple series have now shown that 3-year overall survival with allogeneic transplant is approximately 60%. However, outcomes with transplant are associated with disease control at the time of transplant. In contrast to B-cell malignancies, treatment decisions for peripheral T-cell lymphomas are supported mostly by phase II studies, retrospective series, and expert opinion. For patients with peripheral T-cell lymphoma able to achieve sufficient disease control, autologous stem cell transplantation in first remission and allogeneic stem cell transplantation in relapsed disease offer modest benefit over chemotherapy alone.

Peripheral Blood Involvement at Staging in Patients With Aggressive Peripheral T-Cell Lymphoma

INTRODUCTION

Peripheral T-Cell Lymphomas (PTCL) are a rare subgroup of lymphomas with a poor outcome.Traditional prognostic measures rely heavily on disease stage, and with the advent of targeted treatment, further stratificationcriteria are needed to guide treatment. To date, the impact of blood involvement at diagnosis on outcomes has not been assessed.

MATERIALS AND METHODS

We retrospectively reviewed blood involvement by flow cytometry at diagnosis in 102 consecutivelytreated patients who had flow cytometry data available at diagnosis. Of these, 78 patients with nodal subtypes were identified andstudied in this analysis.

RESULTS

Of 78 patients with nodal subtypes of PTCL who had flow data available at the time ofdiagnosis, circulating populations of malignant T cells matching those in the biopsied lymph nodes were found in 21 patients bymultiparameter flow cytometry. A positive flow cytometry was highly correlated with bone marrow involvement. The patientswith a negative flow cytometry had a trend toward a longer median PFS compared to those with a positive flow but there was noimpact on overall survival.

CONCLUSIONS

Circulating malignant tumor cells can be found in the peripheral blood in a subset ofpatients with aggressive nodal T-cell lymphomas, including peripheral t-cell lymphoma not otherwise specified andangioimmunoblastic T-cell lymphomas, and blood involvement is correlated with bone marrow involvement.

Pathological and Molecular Features of Nodal Peripheral T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCLs) are uncommon neoplasms derived from mature T cells or NK cells. PTCLs comprise numerous disease entities, with over 30 distinct entities listed in the latest WHO classification. They predominantly affect adults and elderly people and usually exhibit an aggressive clinical course with poor prognosis. According to their presentation, PTCLs can be divided into nodal, extranodal or cutaneous, and leukemic types. The most frequent primary sites of PTCLs are lymph nodes, with over half of cases showing nodal presentation. Nodal PTCLs include ALK-positive and ALK-negative anaplastic large cell lymphoma; nodal T-cell lymphoma with T follicular helper cell origin; and PTCL, not otherwise specified. Adult T-cell leukemia/lymphoma also frequently affects lymph nodes. Recent pathological and molecular findings in nodal PTCLs have profoundly advanced the identification of tumor signatures and the refinement of the classification. Therefore, the therapies and pathological diagnosis of nodal PTCLs are continually evolving. This paper aims to provide a summary and update of the pathological and molecular features of nodal PTCLs, which will be helpful for diagnostic practice.

Monomorphic epitheliotropic intestinal T-cell lymphoma comprises morphologic and genomic heterogeneity impacting outcome

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare aggressive T-cell lymphoma most reported in Asia. We performed a comprehensive clinical, pathological and genomic study of 71 European MEITL patients (36 males, 35 females, median age 67 years). The majority presented with gastrointestinal involvement and had emergency surgery, and 40% had stage IV disease. The tumors were morphologically classified into two groups: typical (58%) and atypical (i.e., non-monomorphic or with necrosis, angiotropism or starry-sky pattern) (42%), sharing a homogeneous immunophenotypic profile (CD3+ [98%] CD4- [94%] CD5- [97%] CD7+ [97%] CD8+ [90%] CD56+ [86%] CD103+ [80%] cytotoxic marker+ [98%]) with more frequent expression of TCRgd (50%) than TCRab (32%). MYC expression (30% of cases) partly reflecting MYC gene locus alterations, correlated with non-monomorphic cytology. Almost all cases (97%) harbored deleterious mutation(s) and/or deletion of the SETD2 gene and 90% had defective H3K36 trimethylation. Other frequently mutated genes were STAT5B (57%), JAK3 (50%), TP53 (35%), JAK1 (12.5%), BCOR and ATM (11%). Both TP53 mutations and MYC expression correlated with atypical morphology. The median overall survival (OS) of 63 patients (43/63 only received chemotherapy after initial surgery) was 7.8 months. Multivariate analysis found a strong negative impact on outcome of MYC expression, TP53 mutation, STAT5B mutation and poor performance status while aberrant B-cell marker expression (20% of cases) correlated with better survival. In conclusion, MEITL is an aggressive disease with resistance to conventional therapy, predominantly characterized by driver gene alterations deregulating histone methylation and JAK/STAT signaling and encompasses genetic and morphologic variants associated with very high clinical risk.

Novel T Follicular Helper-like T-Cell Lymphoma Therapies: From Preclinical Evaluation to Clinical Reality

Simple Summary

This work reviews the multiple efforts that have been and are being invested by researchers as well as clinicians to improve the treatment of a specific T-cell lymphoma called follicular helper peripheral T-cell lymphoma. Still, though treatments for B-cell lymphomas have improved, this particular T-cell lymphoma has little to no new therapeutic options that show marked improvements in the survival of the patients compared to treatment with chemotherapy. We report here the evaluation of targeted new therapies for this T-cell lymphoma in new preclinical models for this cancer or in clinical trials with the objective to offer better (combination) treatment options.

Abstract

The classification of peripheral T-cell lymphomas (PTCL) is constantly changing and contains multiple subtypes. Here, we focus on Tfh-like PTCL, to which angioimmunoblastic T-cell lymphoma (AITL) belongs, according to the last WHO classification. The first-line treatment of these malignancies still relies on chemotherapy but gives very unsatisfying results for these patients. Enormous progress in the last decade in terms of understanding the implicated genetic mutations leading to signaling and epigenetic pathway deregulation in Tfh PTCL allowed the research community to propose new therapeutic approaches. These findings point towards new biomarkers and new therapies, including hypomethylating agents, such as azacytidine, and inhibitors of the TCR-hyperactivating molecules in Tfh PTCL. Additionally, metabolic interference, inhibitors of the NF-κB and PI3K-mTOR pathways and possibly novel immunotherapies, such as antibodies and chimeric antigen receptors (CAR) directed against Tfh malignant T-cell surface markers, are discussed in this review among other new treatment options.

Parallel evolution of two distinct lymphoid proliferations in clonal haematopoiesis

AIMS

Angioimmunoblastic T-cell lymphoma (AITL) is genetically characterized by TET2 and DNMT3A mutations occurring in haematopoietic progenitor cells, and late events (e.g. the RHOA-G17V mutation) associated with malignant transformation. As TET2/DNMT3A-mutated progenitor cells can differentiate into multilineage progenies and give rise to both AITL and myeloid neoplasms, they may also have the potential to lead to other metachronous/synchronous neoplasms. We report two cases showing parallel evolution of two distinct potentially neoplastic lymphoid proliferations from a common mutated haematopoietic progenitor cell population.

METHODS AND RESULTS

Both cases presented with generalized lymphadenopathy. In case 1 (a 67-year-old female), an initial lymph node (LN) biopsy was dismissed as reactive, but a repeat biopsy showed a nodal marginal zone lymphoma (NMZL)-like proliferation with an increase in the number of T-follicular helper (TFH) cells. Immunohistochemistry, and clonality and mutational analyses by targeted sequencing of both whole tissue sections and microdissected NMZL-like lesions, demonstrated a clonal B-cell proliferation that harboured the BRAF-G469R mutation and shared TET2 and DNMT3A mutations with an underlying RHOA-G17V-mutant TFH proliferation. Review of the original LN biopsy showed histological and immunophenotypic features of AITL. In case 2 (a 66-year-old male), cytotoxic T-cell lymphoma with an increase in the number of Epstein-Barr virus-positive large B cells was diagnosed on initial biopsy. On review together with the relapsed biopsy, we identified an additional occult neoplastic TFH proliferation/smouldering AITL. Both T-cell proliferations shared TET2 and DNMT3A mutations while RHOA-G17V was confined to the smouldering AITL.

CONCLUSIONS

In addition to demonstrating diagnostic challenges, these cases expand the potential of clonal haematopoiesis in the development of different lineage neoplastic proliferations.

Genetic profiling and biomarkers in peripheral T-cell lymphomas: current role in the diagnostic work-up

Peripheral T-cell lymphomas are a heterogeneous, and usually aggressive, group of mature T-cell neoplasms with overlapping clinical, morphologic and immunologic features. A large subset of these neoplasms remains unclassifiable with current diagnostic methods ("not otherwise specified"). Genetic profiling and other molecular tools have emerged as widely applied and transformative technologies for discerning the biology of lymphomas and other hematopoietic neoplasms. Although the application of these technologies to peripheral T-cell lymphomas has lagged behind B-cell lymphomas and other cancers, molecular profiling has provided novel prognostic and diagnostic markers as well as an opportunity to understand the biologic mechanisms involved in the pathogenesis of these neoplasms. Some biomarkers are more prevalent in specific T-cell lymphoma subsets and are being used currently in the diagnosis and/or risk stratification of patients with peripheral T-cell lymphomas. Other biomarkers, while promising, need to be validated in larger clinical studies. In this review, we present a summary of our current understanding of the molecular profiles of the major types of peripheral T-cell lymphoma. We particularly focus on the use of biomarkers, including those that can be detected by conventional immunohistochemical studies and those that contribute to the diagnosis, classification, or risk stratification of these neoplasms.

Natural Killer T Cell Intravascular Lymphoma With Presentation of Musculoskeletal Pain: A Case Report

Natural killer T cell intravascular lymphoma is a rare category of lymphoma among older individuals. The presentation of natural killer T cell lymphoma varies, causing diagnostic challenges for clinicians. Thus far, only a few studies have reported this condition in the context of musculoskeletal symptoms. We encountered a case of natural killer T cell intravascular lymphoma in a patient who presented with symptoms of sternoclavicular arthritis and femoral pain. The initial diagnosis was undifferentiated hematologic malignancy because undifferentiated hematologic malignant cells were seen on the bone marrow biopsy. Further examination showed that the patient had a high fever and abnormal cells in the blood. Flow cytometry findings revealed the abnormal cells as CD16 and CD56 positive, leading to the diagnosis of natural killer T cell intravascular lymphoma. This is the first report indicating the possibility of natural killer T cell intravascular lymphoma as one of the differential diagnoses of acute joint and muscular pains among older patients and the importance of assessing multiple organs, including musculoskeletal organs, to diagnose intravascular lymphoma.

SOHO State of the Art Updates and Next Questions: Pathology and Pathogenesis of Nodal Peripheral T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous and often clinically aggressive group of neoplasms derived from mature post-thymic T-lymphocytes. These neoplasms are rare and usually diagnostically challenging. Our understanding of the pathogenesis of PTCL is increasing and this improved knowledge is leading us to better molecular characterization, more objective and accurate diagnostic criteria, more effective risk assessment, and potentially better treatments. The focus of this paper is to present a brief overview of the current pathology criteria and molecular and genetic features of nodal peripheral T-cell lymphomas focusing on distinct genetically and molecularly defined subgroups that are being recognized within each major nodal PTCL category. It is expected that the molecular stratification will improve the diagnosis and will provide novel therapeutic opportunities (biomarker-driven and targeted therapies) that might benefit and change the outcomes of patients with these neoplasms.

Mutation analysis links angioimmunoblastic T-cell lymphoma to clonal hematopoiesis and smoking

Background

Although advance has been made in understanding the pathogenesis of mature T-cell neoplasms, the initiation and progression of angioimmunoblastic T-cell lymphoma (AITL) and peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS), remain poorly understood. A subset of AITL/PTCL-NOS patients develop concomitant hematologic neoplasms (CHN), and a biomarker to predict this risk is lacking.

Methods

We generated and analyzed the mutation profiles through 537-gene targeted sequencing of the primary tumors and matched bone marrow/peripheral blood samples in 25 patients with AITL and two with PTCL-NOS.

Results

Clonal hematopoiesis (CH)-associated genomic alterations, found in 70.4% of the AITL/PTCL-NOS patients, were shared among CH and T-cell lymphoma, as well as concomitant myeloid neoplasms or diffuse large B-cell lymphoma (DLBCL) that developed before or after AITL. Aberrant AID/APOBEC activity-associated and tobacco smoking-associated mutational signatures were respectively enriched in the early CH-associated mutations and late non-CH-associated mutations during AITL/PTCL-NOS development. Moreover, analysis showed that the presence of CH harboring ≥2 pathogenic TET2 variants with ≥15% of allele burden conferred higher risk for CHN (p=0.0006, hazard ratio = 14.01, positive predictive value = 88.9%, negative predictive value = 92.1%).

Conclusions

We provided genetic evidence that AITL/PTCL-NOS, CH, and CHN can frequently arise from common mutated hematopoietic precursor clones. Our data also suggests smoking exposure as a potential risk factor for AITL/PTCL-NOS progression. These findings provide insights into the cell origin and etiology of AITL and PTCL-NOS and provide a novel stratification biomarker for CHN risk in AITL patients.

Funding

R01 grant (CA194547) from the National Cancer Institute to WT.

Characteristics of T- and NK-cell Lymphomas After Renal Transplantation: A French National Multicentric Cohort Study

BACKGROUND

Posttransplant lymphoproliferative disorders (PTLDs) encompass a spectrum of heterogeneous entities. Because the vast majority of cases PTLD arise from B cells, available data on PTLD of T or NK phenotype (T/NK-cell PTLD) are scarce, which limits the quality of the management of these patients.

METHODS

All adult cases of PTLD diagnosed in France were prospectively recorded in the national registry between 1998 and 2007. Crosschecking the registry data with 2 other independent national databases identified 58 cases of T/NK-cell PTLD. This cohort was then compared with (i) the 395 cases of B-cell PTLD from the registry, and of (ii) a cohort of 148 T/NK-cell lymphomas diagnosed in nontransplanted patients.

RESULTS

T/NK-cell PTLD occurred significantly later after transplantation and had a worse overall survival than B-cell PTLD. Two subtypes of T/NK-cell PTLD were distinguished: (i) cutaneous (28%) and (ii) systemic (72%), the latter being associated with a worse prognosis. Compared with T/NK-cell lymphomas of nontransplanted patients, overall survival of systemic T/NK-cell PTLD was worse (hazard ratio: 2.64 [1.76-3.94]; P < 0.00001).

CONCLUSIONS

This difference, which persisted after adjustment on tumoral mass, histological subtype, and extension of the disease at diagnosis could be explained by the fact that transplanted patients were less intensively treated and responded less to chemotherapy.

Angioimmunoblastic T-Cell Lymphoma and Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma: A Novel Form of Composite Lymphoma Potentially Mimicking Richter Syndrome

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is an indolent small B-cell neoplasm that may transform into a clinically aggressive disease, namely Richter syndrome, usually as diffuse large B-cell lymphoma. Besides, CLL/SLL encompasses an increased risk of developing other secondary cancers, including a variety of T-cell lymphomas, often of the anaplastic large-cell type or with a cytotoxic phenotype. Here, we report a small series of patients with composite lymphomas consisting of CLL/SLL and angioimmunoblastic T-cell lymphoma (AITL), a hitherto unrecognized association. The 3 patients (1 male/2 females, 68 to 83 y) presented with high-grade-type symptoms. One patient was clinically suspicious for Richter syndrome, in the others CLL/SLL and AITL were concomitant de novo diagnoses. CLL/SLL and AITL were admixed in the same lymph nodes (3/3 cases) and in the bone marrow (1/2 cases). In all cases, the AITL comprised prominent clear cells with a strong T follicular helper immunophenotype and similar mutations consisting of TET2 or DNMT3A alterations, IDH2 R172K/M, and RHOA G17V. The 3 patients received chemotherapy. One died of early AITL relapse. The other 2 remained in complete remission of AITL, 1 died with recurrent CLL, and 1 of acute myeloid leukemia. These observations expand the spectrum of T-cell lymphoma entities that occur in association with CLL/SLL, adding AITL to the rare variants of aggressive neoplasms manifesting as Richter syndrome. Given that disturbances of T-cell homeostasis in CLL/SLL affect not only cytotoxic but also helper T-cell subsets, these may contribute to the emergence of neoplasms of T follicular helper derivation.

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.

Clinicopathologic Features of Peripheral T-Cell Lymphoma in Sub-Saharan Africa

OBJECTIVES

Peripheral T-cell lymphomas (PTCLs) are heterogeneous, clinically aggressive, and rare. Subtype distribution varies by geographic location; however, data from sub-Saharan Africa (SSA) are lacking. We sought to elucidate clinicopathologic features of PTCL in SSA.

METHODS

We reviewed PTCL consultation cases from three SSA countries. PTCL subtype was determined per 2017 World Health Organization classification. Cases with sufficient material were evaluated by polymerase chain reaction for human T-cell leukemia virus type 1 (HTLV-1) and T-cell receptor γ (TCRG) rearrangement.

RESULTS

Among 32 cases, median age was 45 years and male-to-female ratio was 1.7. Thirty (94%) of 32 cases required additional workup for subclassification. PTCL, not otherwise specified (PTCL-NOS) was the most common subtype (13/32, 41%), followed by PTCL with T-follicular helper phenotype (6/32, 19%) and systemic anaplastic large cell lymphoma (6/32, 19%). Four (16%) of 25 cases were Epstein-Barr virus positive (EBV+) (2/2 extranodal natural killer/T-cell lymphoma, 1/13 PTCL-NOS, and 1/4 angioimmunoblastic T-cell lymphoma with EBV+ immunoblasts). Two (15%) of 13 patients with PTCL-NOS were human immunodeficiency virus positive. No cases with evaluable DNA (0/15) were HTLV-1 positive, and 9 of 10 showed clonal TCRG rearrangements.

CONCLUSIONS

In comparison to Western studies, PTCLs from SSA show similar subtype distribution and male predominance but a younger age at diagnosis. Appropriate diagnosis of PTCL requires extensive ancillary testing not readily available in low-income countries, including much of SSA.

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.

Conditional survival and hazards of death for peripheral T-cell lymphomas

Typically, peripheral T-cell lymphoma (PTCLs) prognosis is estimated using overall survival before treatment. However, these estimates cannot show how prognosis evolves with the changing hazard rate over time. Patients (n = 650) with newly diagnosed PTCLs were enrolled retrospectively. After a median follow-up of 5.4 years, angioimmunoblastic T-cell lymphoma, peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) and NK/T cell lymphoma had initially lower 3-year conditional overall survival (COS3; i.e., the 3-year conditional overall survival was defined as the probability of surviving an additional 3 years) and higher hazards of death (26–44.3%). However, after 2 years, the COS3 increased and the death risk decreased over time, whereas anaplastic lymphoma kinase-positive anaplastic large-cell lymphoma constantly had a lower risk over time (0–19.5%). For patients with complete remission after initial treatment, prognosis varied by histological subtypes, with PTCL, NOS having a negative impact. Our data suggested that the risk stratification using the International Prognostic Index might not accurately predict the COS3 for survivors of PTCLs. The COS3 provided time-dependent prognostic information for PTCLs, representing a possible surrogate prognosis indicator for long-term survivors after systemic chemotherapy.

Real-life targeted next-generation sequencing for lymphoma diagnosis over 1 year from the French Lymphoma Network

As the impact of targeted next-generation sequencing (TNGS) on daily diagnosis has not been evaluated, we performed TNGS (46 genes) on lymphomas of unclear subtype following expert haematopathological review. The potential impact on patient care and modifications of final diagnosis were divided into major and minor changes according to the European Society of Medical Oncology (ESMO) guidelines. Among 229 patients [19 primary central nervous system lymphomas (PCNSL), 48 large B-cell lymphomas (LBCLs), 89 small BCLs (SBCLs), seven Hodgkin lymphomas (HL), 66 T-cell lymphomas], the overall concordance rate of histological and TNGS diagnosis was 89·5%. TNGS confirmed the histological diagnosis in 144 cases (62·9%), changed the diagnosis in 24 cases (10·5%) and did not help to clarify diagnosis in 61 cases (26·7%). Modifications to the final diagnosis had a clinical impact on patient care in 8·3% of cases. Diagnostic modifications occurred in all types of lymphoma except in PCNSL and HL; the modification rate was 14·6% in SBCL and 12·5% in LBCL. While comparing informative and uninformative cases, no differences were found in terms of DNA amplification, quality or depth of sequencing and biopsy type. The present study highlights that TNGS may directly contribute to a more accurate diagnosis in difficult-to-diagnose lymphomas, thus improving the clinical management in routine practice.

Management of ALCL and other CD30+ peripheral T-cell lymphomas with a focus on Brentuximab vedotin

Peripheral T-cell lymphomas (PTCL) are rare lymphoproliferative disorders with poor outcomes and high rates of relapse. Incidence varies although the most common subtypes include PTCL-not-otherwise specified, anaplastic large cell lymphoma, and angioimmunoblastic T-cell lymphoma. Anaplastic large cell lymphoma is characterized by near-universal CD30 expression and serves as a prototypic model for other CD30-expressing lymphomas. Historically, these neoplasms have been treated with regimens used in the treatment of aggressive B-cell lymphomas. Over the last decade, brentuximab vedotin, an antibody-drug conjugate, has been investigated to treat peripheral T-cell lymphomas expressing CD30. While first studied in the relapsed and refractory setting, it was later studied in the frontline setting in the ECHELON-2 trial with positive results and is now an approved treatment for CD30-expressing peripheral T-cell lymphomas. Other treatment options in the relapsed and refractory setting include histone deacetylase inhibitors, pralatrexate, and salvage multiagent chemotherapy regimens. Current research is underway regarding combination therapies and the use of other novel agents.