Analysis of Peripheral T-cell Lymphoma Diagnostic Workup in the United States

An exploratory study on the differential diagnostic indicators between adult systemic EBV-positive T-cell lymphoproliferative disorders and angioimmunoblastic T-cell lymphoma with multiple EBV infections

BACKGROUND

The differential diagnosis between adult systemic EBV-positive T-cell lymphoproliferative disorders (EBV+ T-LPD) and angioimmunoblastic T-cell lymphoma (AITL) with multiple EBV infections is difficult, and distinguishing between the two has become a diagnostic challenge for pathologists. Given that the clinical treatment plans are different, an accurate diagnosis is a prerequisite to ensure effective treatment, therefore, it is extremely necessary and meaningful to find effective pathological indicators for distinguishing between two diseases.

METHODS

We present a retrospective study comparing 7 cases of adult EBV+ T-LPD and 16 cases of AITL with multiple EBV infections diagnosed at our institution from 2017 to 2022. Differences in immunophenotype, type of EBV-infected cells, clonality and gene mutations between the two groups of cases were compared by immunohistochemical staining, double-label staining, TCR gene rearrangement and next-generation sequencing analysis.

RESULTS

7 cases of adult EBV+ T-LPD: all cases had no more than 1 T follicular helper (THF) marker was expressed, and there were significantly more EBER+/CD3 + cells than EBER+/CD20 + cells; 5 cases had mutation detection results, in which only 1 had the characteristic KMT2D mutation, 2 had TET2 mutations, and no common mutations such as DDX3X were detected.16 cases of AITL with multiple EBV infections: all cases were found to express at least 2 TFH markers, with 87% of them expressing at least 3 TFH markers., and had significantly more EBER+/CD20 + cells than EBER+/CD3 + cells; 4 cases had mutation test results, with mutated high-frequency genes being TET2 (100%, and all of them had 2 or more TET2 mutations) and RHOA G17V (100%), DNMT3A mutation occurred in 2 cases (50%), and IDH2 R172 mutation occurred in 1 case (25%).

CONCLUSIONS

We found that the expression pattern of TFH markers, the types of cells predominantly infected by EBV and the different mutations can all be used as effective pathological indicators for distinguishing between two diseases.

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.

How molecular advances may improve the diagnosis and management of PTCL patients

Peripheral T-cell lymphomas (PTCL) comprised more than 30 rare heterogeneous entities, representing 10 to 15% of adult non-Hodgkin lymphomas. Although their diagnosis is still mainly based on clinical, pathological, and phenotypic features, molecular studies have allowed for a better understanding of the oncogenic mechanisms involved and the refinement of many PTCL entities in the recently updated classifications. The prognosis remains poor for most entities (5-year overall survival < 30%), with current conventional therapies based on anthracyclin-based polychemotherapy regimen, despite many years of clinical trials. The recent use of new targeted therapies appears to be promising for relapsed/refractory patients, such as demethylating agents in T-follicular helper (TFH) PTCL. However further studies are needed to evaluate the proper combination of these drugs in the setting of front-line therapy. In this review, we will summarize the oncogenic events for the main PTCL entities and report the molecular targets that have led to the development of new therapies. We will also discuss the development of innovative high throughput technologies that aid the routine workflow for the histopathological diagnosis and management of PTCL patients.

The diagnosis and management of suspected lymphoma in general practice

With rapid advancements in diagnosis and treatment of malignancies, the gap between generalists and subspecialists continues to widen, particularly in cancers like lymphoma where the spectrum of disease varies from indolent to rapidly progressive. Prior to establishing with a hematologist/oncologist, patients must be accurately and comprehensively diagnosed and managed for lymphoma in the generalist setting. In the following manuscript, we review the common clinical presentations in which should raise concern for lymphoma. We summarize the literature regarding the role of laboratory studies including complete blood count and peripheral blood flow cytometry, the recommendations for lymph node sampling, the role and selection of imaging modalities, and ideal patient monitoring for high-risk clinical syndromes that may be encountered in lymphoma.

Best Practices in CD30 Immunohistochemistry Testing, Interpretation, and Reporting: An Expert Panel Consensus

CONTEXT.—

Although CD30 testing is an established tool in the diagnostic workup of lymphomas, it is also emerging as a predictive biomarker that informs treatment. The current definition of CD30 positivity by immunohistochemistry is descriptive and based on reactivity in lymphomas that are defined by their universal strong expression of CD30, rather than any established threshold. Challenges include inconsistencies with preanalytic variables, tissue processing, pathologist readout, and with the pathologist and oncologist interpretation of reported results.

OBJECTIVE.—

To develop and propose general best practice recommendations for reporting CD30 expression by immunohistochemistry in lymphoma biopsies to harmonize practices across institutions and facilitate assessment of its significance in clinical decision-making.

DESIGN.—

Following literature review and group discussion, the panel of 14 academic hematopathologists and 2 clinical/academic hematologists/oncologists divided into 3 working groups. Each working group was tasked with assessing CD30 testing by immunohistochemistry, CD30 expression readout, or CD30 expression interpretation.

RESULTS.—

Panel recommendations were reviewed and discussed. An online survey was conducted to confirm the consensus recommendations.

CONCLUSIONS.—

CD30 immunohistochemistry is required for all patients in whom classic Hodgkin lymphoma and any lymphoma within the spectrum of peripheral T-cell lymphoma are differential diagnostic considerations. The panel reinforced and summarized that immunohistochemistry is the preferred methodology and any degree of CD30 expression should be reported. For diagnostic purposes, the interpretation of CD30 expression should follow published guidelines. To inform therapeutic decisions, report estimated percent positive expression in tumor cells (or total cells where applicable) and record descriptively if nontumor cells are positive.

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.

DNMT3A mutations define a unique biological and prognostic subgroup associated with cytotoxic T cells in PTCL-NOS

Peripheral T-cell lymphomas (PTCLs) are heterogenous T-cell neoplasms often associated with epigenetic dysregulation. We investigated de novo DNA methyltransferase 3A (DNMT3A) mutations in common PTCL entities, including angioimmunoblastic T-cell lymphoma and novel molecular subtypes identified within PTCL-not otherwise specified (PTCL-NOS) designated as PTCL-GATA3 and PTCL-TBX21. DNMT3A-mutated PTCL-TBX21 cases showed inferior overall survival (OS), with DNMT3A-mutated residues skewed toward the methyltransferase domain and dimerization motif (S881-R887). Transcriptional profiling demonstrated significant enrichment of activated CD8+ T-cell cytotoxic gene signatures in the DNMT3A-mutant PTCL-TBX21 cases, which was further validated using immunohistochemistry. Genomewide methylation analysis of DNMT3A-mutant vs wild-type (WT) PTCL-TBX21 cases demonstrated hypomethylation in target genes regulating interferon-γ (IFN-γ), T-cell receptor signaling, and EOMES (eomesodermin), a master transcriptional regulator of cytotoxic effector cells. Similar findings were observed in a murine model of PTCL with Dnmt3a loss (in vivo) and further validated in vitro by ectopic expression of DNMT3A mutants (DNMT3A-R882, -Q886, and -V716, vs WT) in CD8+ T-cell line, resulting in T-cell activation and EOMES upregulation. Furthermore, stable, ectopic expression of the DNMT3A mutants in primary CD3+ T-cell cultures resulted in the preferential outgrowth of CD8+ T cells with DNMT3AR882H mutation. Single-cell RNA sequencing(RNA-seq) analysis of CD3+ T cells revealed differential CD8+ T-cell subset polarization, mirroring findings in DNMT3A-mutated PTCL-TBX21 and validating the cytotoxic and T-cell memory transcriptional programs associated with the DNMT3AR882H mutation. Our findings indicate that DNMT3A mutations define a cytotoxic subset in PTCL-TBX21 with prognostic significance and thus may further refine pathological heterogeneity in PTCL-NOS and suggest alternative treatment strategies for this subset.

Genetic alterations and oxidative stress in T cell lymphomas

T cell lymphomas encompass a diverse group of Non-Hodgkin lymphomas with a wide spectrum of clinical, immunological and pathological manifestations. In the last two decades there has been a progress in our understanding of the cell of origin, genetic abnormalities and their impact on behaviour in T cell lymphomas. Genetic alterations are one of the critical drivers of the pathogenesis of T cell lymphoma. Disease progression has been correlated with multiple genetic abnormalities where malignant clones arise primarily out of the host immune surveillance arsenal. There are many cellular processes involved in disease development, and some of them are T cell signaling, differentiation, epigenetic modifications, and immune regulation. Modulation of these crucial pathways via genetic mutations and chromosomal abnormalities possessing either point or copy number mutations helps tumor cells to develop a niche favourable for their growth via metabolic alterations. Several metabolic pathways especially regulation of redox homeostasis is critical in pathogenesis of lymphoma. Disruption of redox potential and induction of oxidative stress renders malignant cells vulnerable to mitochondrial damage and triggers apoptotic pathways causing cell death. Targeting genetic abnormalities and oxidative stress along with current treatment regime have the potential for improved therapeutics and presents new combination approaches towards selective treatment of T cell lymphomas.

Recent Advances in the Management of Relapsed and Refractory Peripheral T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCLs) are a group of heterogeneous lymphomas with poor overall prognosis, particularly in the setting of relapsed/refractory PTCL. Given the limited efficacy of current therapies, several different novel therapies encompassing multiple different mechanisms of action have been evaluated for relapsed and refractory PTCLs. In this review, we explore the current standard of care for relapsed/refractory PTCL, and evaluate in depth novel and emerging therapies, their scientific basis, and current trials for relapsed/refractory PTCL.

Peripheral T-Cell Lymphomas: Therapeutic Approaches

Simple Summary

Peripheral T-cell lymphomas are a group of rare cancers of T cells or natural killer cells, most often with a poor prognosis. In recent years, significant progress has been made through the development of more specific therapies. This review aims to provide an up-to-date overview of current treatments in nodal PTCL.

Abstract

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of rare neoplasms of mature T cells or natural killer (NK) cell. PTCLs usually have an aggressive course and a poor outcome. In recent years, significant progress has been made in the knowledge of the molecular lymphomagenesis of PTCLs, and through the development of new, more specific therapeutic molecules, one can hope in the coming years for more personalized medicine and improved patient prognosis. This review aims to provide an up-to-date overview of the current therapeutic approaches in nodal PTCLs.

CD30+ Lymphoproliferative Disorders as Potential Candidates for CD30-Targeted Therapies

CONTEXT.—

In the early 1980s, a monoclonal antibody termed Ki-1 was developed against a cell line derived from a patient with Hodgkin lymphoma. This antibody detected a limited number of benign activated lymphocytes in lymphoid tissue, whereas in Hodgkin lymphoma it appeared to be nearly specific for Reed-Sternberg cells and their mononuclear variants. Subsequent studies showed that Ki-1 expression defined a new type of lymphoma that was later designated anaplastic large cell lymphoma with or without anaplastic large cell kinase expression/translocation. In the past 30 years, numerous new lymphoma entities have been defined, many of which are variably positive for CD30. Many virally transformed lymphoproliferative disorders are also frequently positive for CD30.

OBJECTIVE.—

To illustrate the broad spectrum of CD30+ hematologic malignancies and to provide an update of CD30-targeted therapies.

DATA SOURCES.—

Personal experiences and published works in PubMed.

CONCLUSIONS.—

Because of its low expression in normal tissue, CD30 was studied as a therapeutic target for many years. However, the first functional humanized antibody against CD30 was developed only about 10 years ago. Brentuximab vedotin is a humanized anti-CD30 antibody linked to a cytotoxin, and was approved by the US Food and Drug Administration in 2012 for treating refractory Hodgkin lymphoma and anaplastic large cell lymphoma. Since then, the list of Food and Drug Administration-approved CD30-targeted hematologic malignancies has grown. Recently, the therapies using tumor antigen-specific chimeric antigen receptor T cells targeting CD30 have incited a great deal of enthusiasm and are studied in clinical trials.

Comparative outcomes for mature T-cell and NK/T-cell lymphomas in people with and without HIV and to AIDS-defining lymphomas

There are no studies comparing the prognosis for mature T-cell lymphoma (TCL) in people with HIV (PWH) to people without HIV (PWoH) and to AIDS-defining B-cell lymphomas (A-BCLs) in the modern antiretroviral therapy era. North American AIDS Cohort Collaboration on Research and Design and Comprehensive Oncology Measures for Peripheral T-cell Lymphoma Treatment are cohorts that enroll patients diagnosed with HIV and TCL, respectively. In our study, 52, 64, 101, 500, and 246 PWH with histologic confirmation of TCL, primary central nervous system lymphoma, Burkitt's lymphoma, diffuse large B-cell lymphoma (DLBCL), and Hodgkin's lymphoma (HL), respectively, and 450 TCLs without HIV were eligible for analysis. At the time of TCL diagnosis, anaplastic large-cell lymphoma (ALCL) was the most common TCL subtype within PWH. Although PWH with TCL diagnosed between 1996 and 2009 experienced a low 5-year survival probability at 0.23 (95% confidence interval [CI]: 0.13, 0.41), we observed a marked improvement in their survival when diagnosed between 2010 and 2016 (0.69; 95% CI: 0.48, 1; P = .04) in contrast to TCLs among PWoH (0.45; 95% CI: 0.41, 0.51; P = .53). Similarly, PWH with ALCLs diagnosed between 1996 and 2009 were associated with a conspicuously inferior 5-year survival probability (0.17; 95% CI: 0.07, 0.42) and consistently lagged behind A-BCL subtypes such as Burkitt's (0.43; 95% CI:0.33, 0.57; P = .09) and DLBCL (0.17; 95% CI: 0.06, 0.46; P = .11) and behind HL (0.57; 95% CI: 0.50, 0.65; P < .0001). Despite a small number, those diagnosed between 2010 and 2016 experienced a remarkable improvement in survival (0.67; 95% CI: 0.3, 1) in comparison with PWoH (0.76; 95% CI: 0.66, 0.87; P = .58). Thus, our analysis confirms improved overall survival for aggressive B- and T-cell malignancies among PWH in the last decade.

Impact of Epstein-Barr Virus on Peripheral T-Cell Lymphoma Not Otherwise Specified and Angioimmunoblastic T-Cell Lymphoma

Purpose

The significance of Epstein-Barr virus (EBV) infections for the prognosis of patients with peripheral T-cell lymphomas (PTCLs), specifically angioimmunoblastic T-cell lymphoma (AITL) and PTCL not otherwise specified (PTCL-NOS), remains unclear. The Epstein-Barr encoding region can be used to detect EBV in tissue sections by in situ hybridization (ISH) and by polymerase chain reaction (PCR) assays of peripheral blood samples from patients with PTCLs. This study compared the outcomes patients with AITL or PTCL-NOS for whom the presence of EBV infection was assessed by these two methods.

Patients and Methods

This was a retrospective study of patients newly diagnosed with AITL or PTCL-NOS. All patients were selected from a single transplantation center. EBV-positive lymphomas were detected at the time of diagnosis in tissue sections by ISH or in the blood by PCR.

Results

Out of a cohort of 140 patients with histologically confirmed AITL or PTCL-NOS, 105 were EBV-positive. The 3-year overall survival of patients with EBV-positive TCL was 43.3% compared to 68.6% in patients with EBV-negative TCL (p = .01). Patients who were treated with autologous or allogeneic hematopoietic stem cell transplantation (n = 28 and n = 11, respectively) or chemotherapy alone (n = 66) had 3-year survival rates of 67.0%, 62.3%, and 30.2%, respectively (p <.02). Patients with EBV-positive TCL had a better prognosis after treatment with hematopoietic stem cell transplantation compared to chemotherapy alone, but no difference was seen among patients with EBV-negative TCL.

Conclusions

EBV infection was shown to negatively affect the clinical outcomes of patients with TCL. Stem cell transplantation has been found to be an effective treatment for EBV-associated lymphomas. Further investigations are warranted to determine the optimal treatment for these patients.

Epigenetic focus on angioimmunoblastic T-cell lymphoma: pathogenesis and treatment

PURPOSE OF REVIEW

Angioimmunoblastic T-cell lymphoma (AITL) is a frequent peripheral T-cell lymphoma affecting elderly patients with a poor outcome when treated with conventional chemotherapy. Molecular studies revealed a homogenous mutational landscape gathering anomalies in genes regulating the DNA methylation and hydroxymethylation and anomalies in T-cell signalling.

RECENT FINDINGS

Recent studies indicate that AITL emerges from a TET2 and/or DNMT3A mutated clonal haematopoiesis. This clonal haematopoiesis bearing mutations altering DNA hydroxymethylation can explain the observed coexistence of AITL with myeloid neoplasms. In addition, AITL development requires AITL-specific mutations, such as the RHOAG17V mutations. Combination of TET2 and RHOAG17V alterations results in the development of AITL-like disease in mouse models. The impact of the presence of these mutations on patient outcome seems limited and new biological factor predicting treatment response and survival remains to be determined. At the therapeutic level, therapies targeting epigenetic changes, such as histone deacetylase inhibitors and the hypomethylating 5-azacytidine agent, could have efficacy in this disease and gave promising results. Recent progress in mouse model development should allow development of new treatments.

SUMMARY

Epigenetic changes are frequent in AITL and could be a promising target.

The expression of CD30 and its clinico-pathologic significance in peripheral T-cell lymphomas

INTRODUCTION

Recent studies have shown that CD30 expression can be an important feature of peripheral and cutaneous T-cell lymphomas (PTCLs and CTCLs) and CD30 testing has increased in importance with the emergence of CD30-directed therapy.

AREAS COVERED

This article reviews the literature on CD30-related biology, prevalence, and therapy in patients with PTCL or CTCL. We searched the PubMed database from 1 January 2010 to 28 April 2020, using terms 'CD30' ('peripheral T-cell lymphomas' or 'cutaneous T-cell lymphoma') and 'immunohistochemistry' or 'flow cytometry' or 'pathology,' and synonyms including terms for T-cell lymphoma subtypes.

EXPERT OPINION

CD30 is expressed at relatively high rates of prevalence across a broad range of PTCLs and CTCLs. CD30 expression may be critical to the development of a subset of PTCLs and also a biomarker for treatment choice in some subtypes. Large-scale randomized, controlled studies have shown that CD30-directed treatment with brentuximab vedotin is significantly more effective against CD30-expressing PTCL and CTCL than current standard-of-care regimens. However, accurate CD30 evaluation is limited by inconsistencies in detection methodology and expression cutoffs defining CD30-expressing disease. Greater understanding of CD30 testing and reporting will enable more patients with CD30-expressing PTCL and CTCL to be identified and treated appropriately.

Prognosis and risk stratification of peripheral T-cell lymphomas

Peripheral T-cell lymphomas represent a rare heterogeneous group of non-Hodgkin lymphomas with generally worse outcomes with standard chemotherapy compared to B-cell lymphomas. Clinical risk prediction tools at baseline have been shown to be prognostic but generally do not impact clinical decision making. However, improving understanding of the prognostic implications of histology and its molecular underpinnings as well as strategies surrounding the use of CD30 as a predictive biomarker for brentuximab vedotin have led to better understanding of how to risk stratify patients. Baseline, interim, and end of treatment PET/CT as evaluated by the Lugano criteria as well as by baseline metabolic tumor volume have also been shown to be prognostic. The role of minimal residual disease tools such as cell free DNA and T-cell gene receptor sequencing remain active areas of investigation in hopes to develop predictive biomarkers in these rare diseases. This review focuses on strategies used to prognosticate in more common forms of peripheral T-cell lymphoma as well as in extranodal NK/T-cell lymphoma.

Strategies for aggressive T-cell lymphoma: divide and conquer

The aggressive peripheral T-cell lymphomas (PTCLs) are a heterogenous group of uncommon lymphomas of mature T lymphocytes dominated by 3 subtypes: systemic anaplastic large-cell lymphoma, both anaplastic lymphoma kinase positive and negative; nodal PTCL with T-follicular helper phenotype; and PTCL, not otherwise specified. Although the accurate diagnosis of T-cell lymphoma and the subtyping of these lymphomas may be challenging, there is growing evidence that knowledge of the subtype of disease can aid in prognostication and in the selection of optimal treatments, in both the front-line and the relapsed or refractory setting. This report focuses on the 3 most common subtypes of aggressive PTCL, to learn how current knowledge may dictate choices of therapy and consultative referrals and inform rational targets and correlative studies in the development of future clinical trials. Finally, I note that clinical-pathologic correlation, especially in cases of T-cell lymphomas that may present with an extranodal component, is essential in the accurate diagnosis and subsequent treatment of our patients.

Advances in understanding of angioimmunoblastic T-cell lymphoma

It has been nearly half a century since angioimmunoblastic T-cell lymphoma (AITL) was characterized in the early 1970’s. Our understanding of the disease has dramatically changed due to multiple discoveries and insights. One of the key features of AITL is aberrant immune activity. Although AITL is now understood to be a neoplastic disease, pathologists appreciated that it was an inflammatory condition. The more we understand AITL at cellular and genetic levels, the more we view it as both a neoplastic and an inflammatory disease. Here, we review recent progress in our understanding of AITL, focusing on as yet unsolved questions.

Brentuximab vedotin in the treatment of CD30+ PTCL

In this timely Blood Spotlight, Barta et al summarize for the practicing hematologist the strengths and limitations of current data on brentuximab vedotin–based treatment in peripheral T-cell lymphoma (PTCL).

Activated-cytotoxic TCRαβ+CD4+ peripheral T-cell lymphoma with hypodermal localization: Case report of a lymphoproliferative disorder probably evolved from the CD4+ cytotoxic T-cell subpopulation

The World Health Organization (WHO) classification of hematopoietic and lymphoid tumors identifies distinctive subtypes of peripheral T-cell lymphoma (PTCL), and, additionally, some PTCLs involving mostly extranodal sites like the skin. The difficulty of classifying PTCLs according to the normal stages of T-cell differentiation and the lack of definitive diagnostic markers for most of the subtypes make the diagnosis of these diseases challenging. PTCL cases which do not fit into any of the specifically defined entities are categorized as PTCL not otherwise specified (PTCL-NOS). PTCLs-NOS represent less than 2% of the total cases of T-cell lymphoma involving the skin. This article illustrates a case of a PTCL-NOS in which tumor cells have an activated cytotoxic TCRαβ+CD3+CD4+CD56+ T-cell phenotype and histopathologic features of subcutaneous panniculitis-like T-cell lymphoma, leading to a fatal outcome.

Defining signatures of peripheral T-cell lymphoma with a targeted 20-marker gene expression profiling assay

Peripheral T-cell lymphoma comprises a heterogeneous group of mature non-Hodgkin lymphomas. Their diagnosis is challenging, with up to 30% of cases remaining unclassifiable and referred to as “not otherwise specified”. We developed a reverse transcriptase-multiplex ligation-dependent probe amplification gene expression profiling assay to differentiate the main T-cell lymphoma entities and to study the heterogeneity of the “not specified” category. The test evaluates the expression of 20 genes, including 17 markers relevant to T-cell immunology and lymphoma biopathology, one Epstein-Barr virus-related transcript, and variants of RHOA (G17V) and IDH2 (R172K/T). By unsupervised hierarchical clustering, our assay accurately identified 21 of 21 ALK-positive anaplastic large cell lymphomas, 16 of 16 extranodal natural killer (NK)/T-cell lymphomas, 6 of 6 hepatosplenic T-cell lymphomas, and 13 of 13 adult T-cell leukemia/lymphomas. ALK-negative anaplastic lymphomas (n=34) segregated into one cytotoxic cluster (n=10) and one non-cytotoxic cluster expressing Th2 markers (n=24) and enriched in DUSP22-rearranged cases. The 63 T_FH-derived lymphomas divided into two subgroups according to a predominant T_FH (n=50) or an enrichment in Th2 (n=13) signatures. We next developed a support vector machine predictor which attributed a molecular class to 27 of 77 not specified T-cell lymphomas: 17 T_FH, five cytotoxic ALK-negative anaplastic and five NK/T-cell lymphomas. Among the remaining cases, we identified two cell-of-origin subgroups corresponding to cytotoxic/Th1 (n=19) and Th2 (n=24) signatures. A reproducibility test on 40 cases yielded a 90% concordance between three independent laboratories. This study demonstrates the applicability of a simple gene expression assay for the classification of peripheral T-cell lymphomas. Its applicability to routinely-fixed samples makes it an attractive adjunct in diagnostic practice.

The role of autologous stem cell transplantation in patients with nodal peripheral T-cell lymphomas in first complete remission: Report from COMPLETE, a prospective, multicenter cohort study

BACKGROUND

The role of autologous stem cell transplantation (ASCT) in the first complete remission (CR1) of peripheral T-cell lymphomas (PTCLs) is not well defined. This study analyzed the impact of ASCT on the clinical outcomes of patients with newly diagnosed PTCL in CR1.

METHODS

Patients with newly diagnosed, histologically confirmed, aggressive PTCL were prospectively enrolled into the Comprehensive Oncology Measures for Peripheral T-Cell Lymphoma Treatment (COMPLETE) study, and those in CR1 were included in this analysis.

RESULTS

Two hundred thirteen patients with PTCL achieved CR1, and 119 patients with nodal PTCL, defined as anaplastic lymphoma kinase-negative anaplastic large cell lymphoma, angioimmunoblastic T-cell lymphoma (AITL), or PTCL not otherwise specified, were identified. Eighty-three patients did not undergo ASCT, whereas 36 underwent consolidative ASCT in CR1. At the median follow-up of 2.8 years, the median overall survival was not reached for the entire cohort of patients who underwent ASCT, whereas it was 57.6 months for those not receiving ASCT (P = .06). ASCT was associated with superior survival for patients with advanced-stage disease or intermediate-to-high International Prognostic Index scores. ASCT significantly improved overall and progression-free survival for patients with AITL but not for patients with other PTCL subtypes. In a multivariable analysis, ASCT was independently associated with improved survival (hazard ratio, 0.37; 95% confidence interval, 0.15-0.89).

CONCLUSIONS

This is the first large prospective cohort study directly comparing the survival outcomes of patients with nodal PTCL in CR1 with or without consolidative ASCT. ASCT may provide a benefit in specific clinical scenarios, but the broader applicability of this strategy should be determined in prospective, randomized trials. These results provide a platform for designing future studies of previously untreated PTCL.

Peripheral T-Cell Lymphoma, not Otherwise Specified (PTCL-NOS)

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) is a World Health Organization (WHO)-defined diagnostic category within the highly heterogeneous group of mature post-thymic T-cell neoplasms. It is the most common subtype of mature post-thymic T-cell neoplasms globally, accounting for up to 35% of PTCL cases in Europe and North America. PTCL-NOS is a diagnosis of exclusion, comprising several disease entities that differ in biology, clinical presentation, and outcome. The diagnosis of PTCL-NOS is made based on the presence of typical histopathological features of lymphoma, an aberrant T-cell immunophenotype, often with a loss of CD5 and CD7, and a clonal T-cell receptor (TCR) gene rearrangement, in the appropriate clinical context. Unlike other types of T-cell lymphoma, recurrent mutations to assist with the diagnosis have not been identified. Patients often present with advanced stage. Prognosis is poor, with a 5-year overall survival (OS) of 20-30%. Anthracycline-based combination chemotherapy remains the most frequently used frontline strategy, with overall response rates (ORR) of 50-60%, and complete response rates (CRR) of 20-30%. Prospective studies with intent-to-treat analyses have shown that consolidation with high-dose chemotherapy and autologous stem cell transplant (ASCT) results in progression-free survivals (PFS) that compare favorably with historical cohorts and may improve OS in selected patient populations. However, randomized data are still lacking. Over the past decade, therapeutic agents approved in the relapsed and refractory setting have produced response rates of up to 33% and median PFS up to 18 months. Overall, outcomes remain poor and there is a dire need for more effective treatments. This review discusses the latest information on the diagnosis and treatment of PTCL-NOS.

Recent Progress in the Understanding of Angioimmunoblastic T-cell Lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) has been classified as a subtype of mature T-cell neoplasms. The recent revision of the WHO classification proposed a new category of nodal T-cell lymphoma with follicular helper T (TFH)-cell phenotype, which was classified into three diseases: AITL, follicular T-cell lymphoma, and nodal peripheral T-cell lymphoma with TFH phenotype. These lymphomas are defined by the expression of TFH-related antigens, CD279/PD-1, CD10, BCL6, CXCL13, ICOS, SAP, and CXCR5. Although recurrent mutations in TET2, IDH2, DNMT3A, RHOA, and CD28, as well as gene fusions, such as ITK-SYK and CTLA4-CD28, were not diagnostic criteria, they may be considered as novel criteria in the near future. Notably, premalignant mutations, tumor-specific mutations, and mutations specific to tumor-infiltrating B cells were identified in AITL. Thus, multi-step and multi-lineage genetic events may lead to the development of AITL.

The discovery and development of romidepsin for the treatment of T-cell lymphoma

INTRODUCTION

Romidepsin is a potent and selective inhibitor of histone deacetylases (HDCAi). It is also the only bicyclic inhibitor to undergo clinical assessment and is considered a promising drug for the treatment of T-cell lymphomas. The cellular action of romidepsin results in enhanced histone acetylation, as well as the acetylation of other nuclear or cytoplasmic proteins, influencing cell cycle, apoptosis, and angiogenesis. In phase II studies involving patients with relapsed or refractory of cutaneous T-cell lymphoma (CTCL) and peripheral T-cell lymphoma (PTCL), romidepsin produced overall response rates (ORR) of 34-35% and 25-38%, with complete response (CR) rates of 6% and 15-18%, respectively. Areas covered: This review summarizes the development of romidepsin, the mechanisms behind its antineoplastic action and its pharmacology. It also covers its pharmacokinetic and pharmacodynamic properties, as well as the preclinical and clinical data on its activity in T-cell lymphoma. Expert opinion: Since there are only few effective therapies available for T-cell lymphomas, romidepsin is a valuable option for relapsed/refractory patients with both CTCL and PTCL. It's also generally well tolerated, and gives potentially durable responses for patients with advanced and symptomatic disease. Combinations of romidepsin with other antineoplastic agents may also further improve drug response and outcomes in T-cell lymphoma.