Identification of a Proliferation Signature Related to Survival in Nodal Peripheral T-Cell Lymphomas

Aberrant MYCN expression drives oncogenic hijacking of EZH2 as a transcriptional activator in peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of hematological cancers arising from the malignant transformation of mature T cells. In a cohort of 28 PTCL cases, we identified recurrent overexpression of MYCN, a member of the MYC family of oncogenic transcription factors. Approximately half of all PTCL cases was characterized by a MYC expression signature. Inducible expression of MYCN in lymphoid cells in a mouse model caused T-cell lymphoma that recapitulated human PTCL with an MYC expression signature. Integration of mouse and human expression data identified EZH2 as a key downstream target of MYCN. Remarkably, EZH2 was found to be an essential cofactor for the transcriptional activation of the MYCN-driven gene expression program, which was independent of methyltransferase activity but dependent on phosphorylation by CDK1. MYCN-driven T-cell lymphoma was sensitive to EZH2 degradation or CDK1 inhibition, which displayed synergy with US Food and Drug Administration-approved histone deacetylase (HDAC) inhibitors.

Genetic Subtyping and Phenotypic Characterization of the Immune Microenvironment and MYC/BCL2 Double Expression Reveal Heterogeneity in Diffuse Large B-cell Lymphoma

PURPOSE

Diffuse large B-cell lymphoma (DLBCL) is molecularly and clinically heterogeneous, and can be subtyped according to genetic alterations, cell-of-origin, or microenvironmental signatures using high-throughput genomic data at the DNA or RNA level. Although high-throughput proteomic profiling has not been available for DLBCL subtyping, MYC/BCL2 protein double expression (DE) is an established prognostic biomarker in DLBCL. The purpose of this study is to reveal the relative prognostic roles of DLBCL genetic, phenotypic, and microenvironmental biomarkers.

EXPERIMENTAL DESIGN

We performed targeted next-generation sequencing; IHC for MYC, BCL2, and FN1; and fluorescent multiplex IHC for microenvironmental markers in a large cohort of DLBCL. We performed correlative and prognostic analyses within and across DLBCL genetic subtypes and MYC/BCL2 double expressors.

RESULTS

We found that MYC/BCL2 double-high-expression (DhE) had significant adverse prognostic impact within the EZB genetic subtype and LymphGen-unclassified DLBCL cases but not within MCD and ST2 genetic subtypes. Conversely, KMT2D mutations significantly stratified DhE but not non-DhE DLBCL. T-cell infiltration showed favorable prognostic effects within BN2, MCD, and DhE but unfavorable effects within ST2 and LymphGen-unclassified cases. FN1 and PD-1-high expression had significant adverse prognostic effects within multiple DLBCL genetic/phenotypic subgroups. The prognostic effects of DhE and immune biomarkers within DLBCL genetic subtypes were independent although DhE and high Ki-67 were significantly associated with lower T-cell infiltration in LymphGen-unclassified cases.

CONCLUSIONS

Together, these results demonstrated independent and additive prognostic effects of phenotypic MYC/BCL2 and microenvironment biomarkers and genetic subtyping in DLBCL prognostication, important for improving DLBCL classification and identifying prognostic determinants and therapeutic targets.

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

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

Peripheral T-cell lymphoma: Molecular profiling recognizes subclasses and identifies prognostic markers

Gene expression and mutational analysis confirm the differences among the 3 peripheral TCL subclasses: AITL, PTCL-NOS, and PTCL-TFH.

The expression of a gene set, including B-cell genes, is an IPI-independent prognostic factor for AITL cases.

Peripheral T-cell lymphoma (PTCL) is a clinically aggressive disease, with a poor response to therapy and a low overall survival rate of approximately 30% after 5 years. We have analyzed a series of 105 cases with a diagnosis of PTCL using a customized NanoString platform (NanoString Technologies, Seattle, WA) that includes 208 genes associated with T-cell differentiation, oncogenes and tumor suppressor genes, deregulated pathways, and stromal cell subpopulations. A comparative analysis of the various histological types of PTCL (angioimmunoblastic T-cell lymphoma [AITL]; PTCL with T follicular helper [TFH] phenotype; PTCL not otherwise specified [NOS]) showed that specific sets of genes were associated with each of the diagnoses. These included TFH markers, cytotoxic markers, and genes whose expression was a surrogate for specific cellular subpopulations, including follicular dendritic cells, mast cells, and genes belonging to precise survival (NF-κB) and other pathways. Furthermore, the mutational profile was analyzed using a custom panel that targeted 62 genes in 76 cases distributed in AITL, PTCL-TFH, and PTCL-NOS. The main differences among the 3 nodal PTCL classes involved the RHOA^G17V mutations (P < .0001), which were approximately twice as frequent in AITL (34.09%) as in PTCL-TFH (16.66%) cases but were not detected in PTCL-NOS. A multivariate analysis identified gene sets that allowed the series of cases to be stratified into different risk groups. This study supports and validates the current division of PTCL into these 3 categories, identifies sets of markers that can be used for a more precise diagnosis, and recognizes the expression of B-cell genes as an IPI-independent prognostic factor for AITL.

Primary cutaneous peripheral T-cell lymphoma, not otherwise specified: results of a multicentre European Organization for Research and Treatment of Cancer (EORTC) cutaneous lymphoma taskforce study on the clinico-pathological and prognostic features

BACKGROUND

Cutaneous peripheral T-cell lymphoma, not otherwise specified (PTL NOS) is an aggressive, but poorly characterized neoplasm.

OBJECTIVES

The European Organization for Research and Treatment of Cancer cutaneous lymphoma taskforce (EORTC CLTF) investigated 33 biopsies of 30 patients with primary cutaneous PTL NOS to analyse their clinical, histological, immunophenotypic features and outcome.

METHODS

Retrospective analysis of clinical data and histopathological features by an expert panel.

RESULTS

Cutaneous PTL NOS manifested clinically either with solitary or disseminated rapidly grown ulcerated tumours or disseminated papulo-nodular lesions. Histologically, a mostly diffuse or nodular infiltrate in the dermis and often extending into the subcutis was found. Epidermotropism was rarely present and only mild and focal. Unusual phenotypes were frequent, e.g. CD3⁺ /CD4^- /CD8^- and CD3⁺ /CD4⁺ /CD8⁺ . Moreover, 18% of the cases exhibited an aberrant expression of the B-cell marker CD20 by the tumour cells. All solitary tumours were located on the limbs and presented a high expression of GATA-3 but this did not correlate with outcome and therefore could not serve as a prognostic factor. The prognosis was shown to be generally poor with 10 of 30 patients (33%) dying of lymphoma within the follow-up of 36 months (mean value; range 3-144). The survival rates were 61% after 3 years (CI, 43-85%) and 54% after 5 years (CI, 36-81%). Small to medium-sized morphology of tumour cells was associated with a better outcome than medium to large or large tumour cells. Age, gender, clinical stage, CD4/CD8 phenotype and GATA-3 expression were not associated with prognosis. Chemotherapy was the most common treatment modality, but surgical excision and/or radiotherapy may represent an appropriate first-line treatment for solitary lesions.

CONCLUSIONS

Cutaneous PTL NOS shows an aggressive course in most patients independent of initial presentation, age and phenotype. Cytomorphology was identified as a prognostic factor. The data indicate a need for more effective treatment modalities in PTL NOS.

Peripheral T cell lymphomas: from the bench to the clinic

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

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

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

Proteomic profiling identifies outcome-predictive markers in patients with peripheral T-cell lymphoma, not otherwise specified

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) constitutes a heterogeneous category of lymphomas, which do not fit into any of the specifically defined T-cell lymphoma entities. Both the pathogenesis and tumor biology in PTCL-NOS are poorly understood. Protein expression in pretherapeutic PTCL-NOS tumors was analyzed by proteomics. Differentially expressed proteins were compared in 3 distinct scenarios: (A) PTCL-NOS tumor tissue (n = 18) vs benign lymphoid tissue (n = 8), (B) clusters defined by principal component analysis (PCA), and (C) tumors from patients with chemosensitive vs refractory PTCL-NOS. Selected differentially expressed proteins identified by proteomics were correlated with clinico-pathological features and outcome in a larger cohort of patients with PTCL-NOS (n = 87) by immunohistochemistry (IHC). Most proteins with altered expression were identified comparing PTCL-NOS vs benign lymphoid tissue. PCA of the protein profile defined 3 distinct clusters. All benign samples clustered together, whereas PTCL-NOS tumors separated into 2 clusters with different patient overall survival rates (P = .001). Differentially expressed proteins reflected large biological diversity among PTCL-NOS, particularly associated with alterations of "immunological" pathways. The 2 PTCL-NOS subclusters defined by PCA showed disturbance of "stress-related" and "protein metabolic" pathways. α-Enolase 1 (ENO1) was found differentially expressed in all 3 analyses, and high intratumoral ENO1 expression evaluated by IHC correlated with poor outcome (hazard ratio, 2.09; 95% confidence interval, 1.17-3.73; P = .013). High expression of triosephosphate isomerase (TPI1) also showed a tendency to correlate with poor survival (P = .057). In conclusion, proteomic profiling of PTCL-NOS provided evidence of markedly altered protein expression and identified ENO1 as a novel potential prognostic marker.

nm23, TOP2A and VEGF expression: Potential prognostic biologic factors in peripheral T-cell lymphoma, not otherwise specified

Peripheral T-cell lymphoma not otherwise specified (PTCL-NOS) is an aggressive lymphoma associated with a poor outcome. To date, the factor consistently associated with prognosis is the International Prognostic Index (IPI) score; however, it is considered that the IPI score cannot be beneficial for guiding potential targeted therapies. New scoring systems have recently been developed. The aim of the present study was to observe the expression of NME/NM23 nucleoside diphosphate kinase 1 (nm23), nuclear DNA topoisomerase 2-α (TOP2A), multiple myeloma oncogene-1 (MUM-1) and vascular endothelial growth factor (VEGF), and evaluate their prognostic value in PTCL-NOS. A retrospective analysis of 124 cases of PTCL-NOS showed that 70/122 (57.4%) cases were positive for nm23, 71/122 (58.2%) for TOP2A, 30/119 (25.2%) for MUM-1 and 64/122 (52.5%) for VEGF. Of note, 50/122 cases concurrently expressed nm23, TOP2A and VEGF. The univariate analysis results revealed that the nm23 (P=0.012), TOP2A (P=0.002) and VEGF (P=0.008) expression had a negative prognostic effect in patients with PTCL-NOS, while the MUM-1 expression did not have a significant prognostic value (P=0.918). In addition, the concurrent expression of nm23, TOP2A and VEGF was significantly associated with a worse prognosis (P=0.002). However, in multivariate Cox regression analysis, the concurrent expression of nm23, TOP2A and VEGF tended to predict a worse prognosis, however the P-value was borderline (hazard ratio, 1.495; 95% confidence interval, 0.993-2.250; P=0.054). It is speculated that there may be an association among the expression of nm23, TOP2A and VEGF, and that their expression may serve as a promising prognostic factor for PTCL-NOS.

Molecular heterogeneity in peripheral T-cell lymphoma, not otherwise specified revealed by comprehensive genetic profiling

Peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) is a diagnosis of exclusion, being the most common entity in mature T-cell neoplasms, and its molecular pathogenesis remains significantly understudied. Here, combining whole-exome and targeted-capture sequencing, gene-expression profiling, and immunohistochemical analysis of tumor samples from 133 cases, we have delineated the entire landscape of somatic alterations, and discovered frequently affected driver pathways in PTCL, NOS, with and without a T-follicular helper (TFH) cell phenotype. In addition to previously reported mutational targets, we identified a number of novel recurrently altered genes, such as KMT2C, SETD1B, YTHDF2, and PDCD1. We integrated these genetic drivers using hierarchical clustering and identified a previously undescribed molecular subtype characterized by TP53 and/or CDKN2A mutations and deletions in non-TFH PTCL, NOS. This subtype exhibited different prognosis and unique genetic features associated with extensive chromosomal instability, which preferentially affected molecules involved in immune escape and transcriptional regulation, such as HLA-A/B and IKZF2. Taken together, our findings provide novel insights into the molecular pathogenesis of PTCL, NOS by highlighting their genetic heterogeneity. These results should help to devise a novel molecular classification of PTCLs and to exploit a new therapeutic strategy for this group of aggressive malignancies.

Novel Insights reveal Anti-microbial Gene Regulation of Piglet Intestine Immune in response to Clostridium perfringens Infection

LncRNA play important roles in regulation of host immune and inflammation responses in defending bacterial infection. Clostridium perfringens (C. perfringens) type C is one of primary bacteria leading to piglet diarrhea and other intestinal inflammatory diseases. For the differences of host immune capacity, individuals usually show resistance and susceptibility to bacterial infection. However, whether and how lncRNAs involved in modulating host immune resistance have not been reported. We have investigated the expression patterns of ileum lncRNAs of 7-day-old piglets infected by C. perfringens type C through RNA sequencing. A total of 16 lncRNAs and 126 mRNAs were significantly differentially expressed in resistance (IR) and susceptibility (IS) groups. Many lncRNAs and mRNAs were identified to regulate resistance and susceptibility of piglets through immune related pathways. Five lncRNAs may have potential function on regulating the expressions of cytokines, these lncRNAs and cytokines work together to co-regulated piglet immune response to C. perfringens, affecting host resistance and susceptibility. These results provide valuable information for understanding the functions of lncRNA and mRNA in affecting piglet diarrhea resistance of defensing to C. perfringens type C, these lncRNAs and mRNAs may be used as the important biomarkers for decreasing C. perfringens spread and diseases in human and piglets.

Molecular and Genomic Landscape of Peripheral T-Cell Lymphoma

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

The curious origins of angioimmunoblastic T-cell lymphoma

PURPOSE OF REVIEW

Once an obscure disease, recent studies have transformed our understanding of angioimmunoblastic T-cell lymphoma (AITL). In this review, we summarize new major advances in the genetics and biology of AITL.

RECENT FINDINGS

Genome wide sequencing studies have dissected the repertoire of the genetic alterations driving AITL uncovering a highly recurrent Gly17Val somatic mutation in the small GTPase RHOA and major role for mutations in epigenetic regulators, such as TET2, DNMT3A and IDH2, and signaling factors (e.g., FYN and CD28). These findings support a multistep model of follicular T helper cell transformation in AITL and pinpoint novel candidates for the development of targeted therapies in this disease.

SUMMARY

AITL originates from follicular T helper cells and is characterized by the presence of RHOA G17V mutation together with genetic alterations in TET2, DNMT3A, and IDH2. Research efforts now focus on the elucidation of the specific roles and interplay of these genetic alterations in the pathogenesis of AITL.

Pitfalls and major issues in the histologic diagnosis of peripheral T-cell lymphomas: results of the central review of 573 cases from the T-Cell Project, an international, cooperative study

Peripheral T-cell lymphomas (PTCLs) comprise a heterogeneous group of neoplasms that are derived from post-thymic lymphoid cells at different stages of differentiation with different morphological patterns, phenotypes and clinical presentations. PTCLs are highly diverse, reflecting the diverse cells from which they can originate and are currently sub-classified using World Health Organization (WHO) 2008 criteria. In 2006 the International T-Cell Lymphoma Project launched the T-Cell Project, building on the retrospective study previously carried on by the network, with the aim to prospectively collect accurate data to improve knowledge on this group of lymphomas. Based on previously published reports from International Study Groups it emerged that rendering a correct classification of PTCLs is quite difficult because the relatively low prevalence of these diseases results in a lack of confidence by most pathologists. This is the reason why the T-Cell Project requested the availability of diagnostic material from the initial biopsy of each patient registered in the study in order to have the initial diagnosis centrally reviewed by expert hematopathologists. In the present report the results of the review process performed on 573 cases are presented. Overall, an incorrect diagnosis was centrally recorded in 13.1% cases, including 8.5% cases centrally reclassified with a subtype eligible for the project and 4.6% cases misclassified and found to be disorders other than T-cell lymphomas; 2.1% cases were centrally classified as T-Cell disorders not included in the study population. Thus, the T-Cell Project confirmed the difficulties in providing an accurate classification when a diagnosis of PTCLs is suspected, singled out the major pitfalls that can bias a correct histologic categorization and confirmed that a centralized expert review with the application of adequate diagnostic algorithms is mandatory when dealing with these tumours. Copyright © 2016 John Wiley & Sons, Ltd.

An exact algorithm for finding cancer driver somatic genome alterations: the weighted mutually exclusive maximum set cover problem

Background

The mutual exclusivity of somatic genome alterations (SGAs), such as somatic mutations and copy number alterations, is an important observation of tumors and is widely used to search for cancer signaling pathways or SGAs related to tumor development. However, one problem with current methods that use mutual exclusivity is that they are not signal-based; another problem is that they use heuristic algorithms to handle the NP-hard problems, which cannot guarantee to find the optimal solutions of their models.

Method

In this study, we propose a novel signal-based method that utilizes the intrinsic relationship between SGAs on signaling pathways and expression changes of downstream genes regulated by pathways to identify cancer signaling pathways using the mutually exclusive property. We also present a relatively efficient exact algorithm that can guarantee to obtain the optimal solution of the new computational model.

Results

We have applied our new model and exact algorithm to the breast cancer data. The results reveal that our new approach increases the capability of finding better solutions in the application of cancer research. Our new exact algorithm has a time complexity of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$O^{*}(1.325^{m})$$\end{document}O∗(1.325m)(Note: Following the recent convention, we use a star * to represent that the polynomial part of the time complexity is neglected), which has solved the NP-hard problem of our model efficiently.

Conclusion

Our new method and algorithm can discover the true causes behind the phenotypes, such as what SGA events lead to abnormality of the cell cycle or make the cell metastasis lose control in tumors; thus, it identifies the target candidates for precision (or target) therapeutics.

Electronic supplementary material

The online version of this article (doi:10.1186/s13015-016-0073-9) contains supplementary material, which is available to authorized users.

[Molecular pathogenesis of peripheral T-cell lymphoma (1): angioimmunoblastic T-cell lymphoma, peripheral T-cell lymphoma, not otherwise specified and anaplastic large cell lymphoma]

Peripheral T-cell lymphomas (PTCL) belong to the group of non-Hodgkin lymphoma and particularly that of mature T/NK cells lymphoproliferative neoplasms. The 2008 WHO classification describes different PTCL entities with varying prevalence. With the exception of the histological subtype "ALK positive anaplastic large cell lymphoma", PTCL are characterized by a poor prognosis. The mechanisms underlying the pathogenesis of these lymphomas are not yet fully understood, but development of genomic high-throughput analysis techniques now allows to extensively identify the molecular abnormalities present in tumor cells. This review aims to summarize the current knowledge and recent advances about the molecular events occurring at the origin or during the natural history of main entities of PTCL. It will be published in two parts : the first is focused on the three more frequent entities, angioimmunoblastic T-cell lymphoma, peripheral T-cell lymphoma, not otherwise specified, and anaplastic large cell lymphoma. The second (which will appear in the november issue) will describe other subtypes less frequent and of poor prognosis : extranodal NK/T-cell lymphoma, nasal type, adult T-cell leukemia/lymphoma, and enteropathy-associated T-cell lymphoma. T or NK cell lymphoproliferative disorders with leukemic presentation, primary cutaneous T-cell lymphoma and very rare subtypes of PTCL whose prevalence is less than 5% (hepatosplenic T-cell lymphoma and subcutaneous panniculitis-like T cell lymphoma) will not be discussed herein.

Changing the paradigms of treatment in peripheral T-cell lymphoma: from biology to clinical practice

Despite enormous advances in our understanding of aggressive lymphomas, it is clear that progress in the peripheral T-cell lymphomas (PTCL) has lagged well behind other B-cell malignancies. Although there are many reasons for this, the one commonly cited notes that the paradigms for diffuse large B-cell lymphoma (DLBCL) were merely applied to all patients with PTCL, the classic "one-size-fits-all" approach. Despite these challenges, progress is being made. Recently, the FDA has approved four drugs for patients with relapsed/refractory PTCL over the past 5 years, and if one counts the recent Japanese approval of the anti-CCR4 monoclonal antibody for patients with adult T-cell leukemia/lymphoma, five drugs have been approved worldwide. These efforts have led to the initiation of no fewer than four randomized clinical studies exploring the integration of these new agents into standard CHOP (cyclophosphamide-Adriamycin-vincristine-prednisone)-based chemotherapy regimens for patients with newly diagnosed PTCL. In addition, a new wave of studies are exploring the merits of novel drug combinations in the disease, an effort to build on the obvious single-agent successes. What has emerged most recently is the recognition that the PTCL may be a disease-characterized by epigenetic dysregulation, which may help explain its sensitivity to histone deacetylase (HDAC) inhibitors, and open the door for even more creative combination approaches. Nonetheless, advances made over a relatively short period of time are changing how we now view these diseases and, hopefully, have poised us to finally improve its prognosis. See all articles in this CCR Focus section, "Paradigm Shifts in Lymphoma."

Digital pathology for the validation of tissue microarrays in peripheral T-cell lymphomas

Systematic validation of construction and analysis parameters when using tissue microarray (TMA) in rare, morphologically heterogenous entities such as peripheral T-cell lymphoma (PTCL) is not reported. We describe a tissue-saving virtual TMA to predetermine the number of cores needed to represent whole tissue sections (WTS) from the same biopsies, using automated and traditional manual methods for the quantification of immunohistochemical stains. Whole paraffin hematoxylin and eosin- and immunohistochemical (CD2, CD30, and Ki-67)-stained sections from 30 PTCLs were digitalized. A virtual TMA with six 1-mm cores per slide was designed to compare agreements in the immunohistochemical scoring. Using digital image analysis and manual stereological counting, immunohistochemical positivity was quantified. Associations were analyzed using the Bland-Altman and correlation plots. In PTCL, we report that 4 cores are required to represent WTS results (ie, agreement within ±10%). High concordance was demonstrated between digital results obtained with WTS compared with 4-core virtual TMA (correlation coefficients: 0.89-0.98), and in the comparative evaluation of 4-core virtual TMA by digital image analysis versus manual stereology (correlation coefficients: 0.91 to 0.99). Virtual TMAs provide an efficient tool for optimizing and validating TMA construction parameters when planning a study. The method can be applied to the same tissues used in a subsequent formal study, without wasting scarce tissue resources. In PTCL, TMAs constructed with four 1-mm cores are representative of WTS. In parallel tests using TMAs and WTS from PTCLs, there is a high level of agreement comparing automated digital with manual stereological methods for the quantification of immunohistochemical biomarker staining.

Pathogenetic and diagnostic significance of microRNA deregulation in peripheral T-cell lymphoma not otherwise specified

Peripheral T-cell lymphomas not otherwise specified (PTCLs/NOS) are rare and aggressive tumours whose molecular pathogenesis and diagnosis are still challenging. The microRNA (miRNA) profile of 23 PTCLs/NOS was generated and compared with that of normal T-lymphocytes (CD4+, CD8+, naive, activated). The differentially expressed miRNA signature was compared with the gene expression profile (GEP) of the same neoplasms. The obtained gene patterns were tested in an independent cohort of PTCLs/NOS. The miRNA profile of PTCLs/NOS then was compared with that of 10 angioimmunoblastic T-cell lymphomas (AITLs), 6 anaplastic large-cell lymphomas (ALCLs)/ALK+ and 6 ALCLs/ALK−. Differentially expressed miRNAs were validated in an independent set of 20 PTCLs/NOS, 20 AITLs, 19 ALCLs/ALK− and 15 ALCLs/ALK+. Two hundred and thirty-six miRNAs were found to differentiate PTCLs/NOS from activated T-lymphocytes. To assess which miRNAs impacted on GEP, a multistep analysis was performed, which identified all miRNAs inversely correlated to different potential target genes. One of the most discriminant miRNAs was selected and its expression was found to affect the global GEP of the tumours. Moreover, two sets of miRNAs were identified distinguishing PTCL/NOS from AITL and ALCL/ALK−, respectively. The diagnostic accuracy of this tool was very high (83.54%) and its prognostic value validated.

Global transcriptome analysis and enhancer landscape of human primary T follicular helper and T effector lymphocytes

T follicular helper (Tfh) cells are a subset of CD4(+) T helper cells that migrate into germinal centers and promote B-cell maturation into memory B and plasma cells. Tfh cells are necessary for promotion of protective humoral immunity following pathogen challenge, but when aberrantly regulated, drive pathogenic antibody formation in autoimmunity and undergo neoplastic transformation in angioimmunoblastic T-cell lymphoma and other primary cutaneous T-cell lymphomas. Limited information is available on the expression and regulation of genes in human Tfh cells. Using a fluorescence-activated cell sorting-based strategy, we obtained primary Tfh and non-Tfh T effector cells from tonsils and prepared genome-wide maps of active, intermediate, and poised enhancers determined by chromatin immunoprecipitation-sequencing, with parallel transcriptome analyses determined by RNA sequencing. Tfh cell enhancers were enriched near genes highly expressed in lymphoid cells or involved in lymphoid cell function, with many mapping to sites previously associated with autoimmune disease in genome-wide association studies. A group of active enhancers unique to Tfh cells associated with differentially expressed genes was identified. Fragments from these regions directed expression in reporter gene assays. These data provide a significant resource for studies of T lymphocyte development and differentiation and normal and perturbed Tfh cell function.

Diagnostic accuracy of a defined immunophenotypic and molecular genetic approach for peripheral T/NK-cell lymphomas. A North American PTCL study group project

The diagnosis of peripheral T-cell and NK-cell lymphomas (PTNKCL) is difficult with few standards for required ancillary studies. We evaluated a series of PTNKCLs using a tiered approach to immunohistochemistry and molecular genetic characterization to document diagnostic accuracy and clinical relevance. Seven hematopathologists reviewed 374 cases that included PTNKCL and non-PTNKCL cases to mimic diagnostic practice. Cases received tier 0, 1, and 2 diagnoses by 3 independent pathologists, on the basis of hematoxylin and eosin stains and progressive immunohistochemistry panels. A tier 2b diagnosis was rendered when gene rearrangement data were available, and a final consensus diagnosis was rendered after discussion of each case. Across all 374 cases, consensus agreement was 92.5%. For PTNKCLs, World Health Organization subclassification was possible in 16.5%, 37.1%, 82.8%, and 85.9% of individual reviewer diagnoses at tier 0, 1, 2, and 2b, respectively. Gene rearrangement contributed to a change in diagnosis in 51 of 647 (8%) individual reviews. Following this algorithm may provide prognostic information on the basis of individual marker expression in common PTNKCL types (CD4 in peripheral T-cell lymphoma, not otherwise specified and PD-1 in angioimmunoblastic T-cell lymphoma). This evidence-based approach to the diagnosis of PTNKCL informs practicing pathologists, clinical trial designers, and policy-makers regarding required ancillary studies.

Gene expression signatures delineate biological and prognostic subgroups in peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) encompasses a heterogeneous group of neoplasms with generally poor clinical outcome. Currently 50% of PTCL cases are not classifiable: PTCL-not otherwise specified (NOS). Gene-expression profiles on 372 PTCL cases were analyzed and robust molecular classifiers and oncogenic pathways that reflect the pathobiology of tumor cells and their microenvironment were identified for major PTCL-entities, including 114 angioimmunoblastic T-cell lymphoma (AITL), 31 anaplastic lymphoma kinase (ALK)-positive and 48 ALK-negative anaplastic large cell lymphoma, 14 adult T-cell leukemia/lymphoma and 44 extranodal NK/T-cell lymphoma that were further separated into NK-cell and gdT-cell lymphomas. Thirty-seven percent of morphologically diagnosed PTCL-NOS cases were reclassified into other specific subtypes by molecular signatures. Reexamination, immunohistochemistry, and IDH2 mutation analysis in reclassified cases supported the validity of the reclassification. Two major molecular subgroups can be identified in the remaining PTCL-NOS cases characterized by high expression of either GATA3 (33%; 40/121) or TBX21 (49%; 59/121). The GATA3 subgroup was significantly associated with poor overall survival (P = .01). High expression of cytotoxic gene-signature within the TBX21 subgroup also showed poor clinical outcome (P = .05). In AITL, high expression of several signatures associated with the tumor microenvironment was significantly associated with outcome. A combined prognostic score was predictive of survival in an independent cohort (P = .004).

Molecular genetics of peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCL) are rare neoplasms that in most instances respond poorly to conventional chemotherapies. Four varieties--PTCL not otherwise specified (NOS), angioimmunoblastic T-cell lymphoma (AITL), ALK+ anaplastic T-cell lymphoma (ALCL), and ALK- ALCL--account for about 60 % of them. Their classification is difficult because of the wide spectrum of morphologic features and the lack of robust immunohistochemical markers. Thus, high-throughput technologies can importantly contribute to their better understanding. In particular, gene expression profiling has cleared the borders among PTCL/NOS, ALK- ALCL and AITL. In fact, gene signatures have been developed even from formalin-fixed paraffin-embedded tissue samples that definitely distinguish one tumor from the other(s). This has important practical implications: for instance on routine diagnostics PTCL/NOS expressing CD30 can be easily confused with ALK- ALCL, but has a much worse prognosis. Therefore, the clear-cut distinction between the two conditions is pivotal to understand the results of ongoing trials with Brentuximab Vedotin, targeting the CD30 molecule. Besides improving the diagnosis, molecular studies have provided the rationale for the usage of novel drugs in the setting of PTCLs, such as ALK inhibitors in ALK+ ALCL, anti-angiogenetic drugs in AITL, and tyrosine kinase inhibitors in PTCL/NOS and ALK+ and ALK- ALCLs.

Platelet-derived growth factor alpha mediates the proliferation of peripheral T-cell lymphoma cells via an autocrine regulatory pathway

Peripheral T-cell lymphomas not otherwise specified (PTCL/NOS) are very aggressive tumors characterized by consistent aberrant expression of platelet-derived growth factor receptor alpha (PDGFRA). In this study, we aimed to identify the determinants of PDGFRA activity in PTCL/NOS and to elucidate the biological consequences of its activation. We observed overexpression of the PDGFRA gene by gene expression profiling in most of the tested PTCLs and confirmed the expression of PDGFRA and phospho-PDGFRA using immunohistochemistry. The integrity of the PDFGRA locus was demonstrated using several different approaches, including massive parallel sequencing and Sanger sequencing. PDGF-AA was found to be expressed and secreted by PTCL/NOS cells and to be necessary and sufficient for PDGFRA phosphorylation ex vivo by sustaining an autocrine stimulation. We documented consistently high PDGF-A expression in primary biopsies and patients' plasma and tracked PDGFRA signaling in primary tumors, achieving evidence of its activation. Indeed, we found that STAT1 and STAT5 are implicated in PDGFRA signaling transduction. Finally, we demonstrated that PDGFRA activation supported tumor cell proliferation and provided the first evidence of the anti-lymphoma activity of PDGRA inhibition in a PTCL/NOS patient. Altogether, our data demonstrated that PDGFRA activity fosters PTCL/NOS proliferation via an autocrine loop.

The microenvironment in T-cell lymphomas: emerging themes

Peripheral T-cell lymphomas (PTCLs) are heterogeneous and uncommon malignancies characterized by an aggressive clinical course and a mostly poor outcome with current treatment strategies. Despite novel insights into their pathobiology provided by recent genome-wide molecular studies, several entities remain poorly characterized. In addition to the neoplastic cell population, PTCLs have a microenvironment component, composed of non-tumor cells and stroma, which is quantitatively and qualitatively variable, and which may have an effect on their pathological and clinical features. The best example is provided by angioimmunoblastic T-cell lymphoma (AITL), a designation reflecting the typical vascularization and reactive immunoblastic content of the tumor tissues. In this disease, a complex network of interactions between the lymphoma cells and the microenvironment exists, presumably mediated by the neoplastic T cells with follicular helper T-cell properties. A better understanding of the crosstalk between neoplastic T or NK cells and their microenvironment may have important implications for guiding the development of novel therapies.

Molecular profiling improves classification and prognostication of nodal peripheral T-cell lymphomas: results of a phase III diagnostic accuracy study

PURPOSE

The differential diagnosis among the commonest peripheral T-cell lymphomas (PTCLs; ie, PTCL not otherwise specified [NOS], angioimmunoblastic T-cell lymphoma [AITL], and anaplastic large-cell lymphoma [ALCL]) is difficult, with the morphologic and phenotypic features largely overlapping. We performed a phase III diagnostic accuracy study to test the ability of gene expression profiles (GEPs; index test) to identify PTCL subtype.

METHODS

We studied 244 PTCLs, including 158 PTCLs NOS, 63 AITLs, and 23 ALK-negative ALCLs. The GEP-based classification method was established on a support vector machine algorithm, and the reference standard was an expert pathologic diagnosis according to WHO classification.

RESULTS

First, we identified molecular signatures (molecular classifier [MC]) discriminating either AITL and ALK-negative ALCL from PTCL NOS in a training set. Of note, the MC was developed in formalin-fixed paraffin-embedded (FFPE) samples and validated in both FFPE and frozen tissues. Second, we found that the overall accuracy of the MC was remarkable: 98% to 77% for AITL and 98% to 93% for ALK-negative ALCL in test and validation sets of patient cases, respectively. Furthermore, we found that the MC significantly improved the prognostic stratification of patients with PTCL. Particularly, it enhanced the distinction of ALK-negative ALCL from PTCL NOS, especially from some CD30+ PTCL NOS with uncertain morphology. Finally, MC discriminated some T-follicular helper (Tfh) PTCL NOS from AITL, providing further evidence that a group of PTCLs NOS shares a Tfh derivation with but is distinct from AITL.

CONCLUSION

Our findings support the usage of an MC as additional tool in the diagnostic workup of nodal PTCL.

CD30-positive peripheral T-cell lymphomas share molecular and phenotypic features

Peripheral T-cell lymphoma, not otherwise specified is a heterogeneous group of aggressive neoplasms with indistinct borders. By gene expression profiling we previously reported unsupervised clusters of peripheral T-cell lymphomas, not otherwise specified correlating with CD30 expression. In this work we extended the analysis of peripheral T-cell lymphoma molecular profiles to prototypical CD30(+) peripheral T-cell lymphomas (anaplastic large cell lymphomas), and validated mRNA expression profiles at the protein level. Existing transcriptomic datasets from peripheral T-cell lymphomas, not otherwise specified and anaplastic large cell lymphomas were reanalyzed. Twenty-one markers were selected for immunohistochemical validation on 80 peripheral T-cell lymphoma samples (not otherwise specified, CD30(+) and CD30(-); anaplastic large cell lymphomas, ALK(+) and ALK(-)), and differences between subgroups were assessed. Clinical follow-up was recorded. Compared to CD30(-) tumors, CD30(+) peripheral T-cell lymphomas, not otherwise specified were significantly enriched in ALK(-) anaplastic large cell lymphoma-related genes. By immunohistochemistry, CD30(+) peripheral T-cell lymphomas, not otherwise specified differed significantly from CD30(-) samples [down-regulated expression of T-cell receptor-associated proximal tyrosine kinases (Lck, Fyn, Itk) and of proteins involved in T-cell differentiation/activation (CD69, ICOS, CD52, NFATc2); upregulation of JunB and MUM1], while overlapping with anaplastic large cell lymphomas. CD30(-) peripheral T-cell lymphomas, not otherwise specified tended to have an inferior clinical outcome compared to the CD30(+) subgroups. In conclusion, we show molecular and phenotypic features common to CD30(+) peripheral T-cell lymphomas, and significant differences between CD30(-) and CD30(+) peripheral T-cell lymphomas, not otherwise specified, suggesting that CD30 expression might delineate two biologically distinct subgroups.

Loss of TCR-beta F1 and/or EZRIN expression is associated with unfavorable prognosis in nodal peripheral T-cell lymphomas

Nodal peripheral T-cell lymphoma (nodal PTCL) has an unfavorable prognosis, and specific pathogenic alterations have not been fully identified. The biological and clinical relevance of the expression of CD30/T-cell receptor (TCR) genes is a topic under active investigation. One-hundred and ninety-three consecutive nodal PTCLs (89 angioimmunoblastic T-cell lymphomas (AITL) and 104 PTCL-unspecified (PTCL-not otherwise specified (NOS)) cases) were analyzed for the immunohistochemical expression of 19 molecules, involving TCR/CD30 pathways and the associations with standard prognostic indices. Mutually exclusive expression was found between CD3 and TCR-beta F1 with CD30 expression. Taking all PTCL cases together, logistic regression identified a biological score (BS) including TCR molecules (TCR-beta F1 and EZRIN) that separates two subgroups of patients with a median survival of 34.57 and 5.20 months (P<0.001). Multivariate analysis identified BS and the prognostic index for PTCL (PIT) score as independent prognostic factors. This BS maintained its significance in multivariate analysis only for the PTCL-NOS subgroup of tumors. In AITL cases, only a high level of ki67 expression was related to prognosis. A BS including molecules involved in the TCR signaling pathway proved to be an independent prognostic factor of poor outcome in a multivariate analysis, specifically in PTCL-NOS patients. Nevertheless, validation in an independent series of homogeneously treated PTCL patients is required to confirm these data.

ESMO Consensus conferences: guidelines on malignant lymphoma. part 2: marginal zone lymphoma, mantle cell lymphoma, peripheral T-cell lymphoma

To complement the existing treatment guidelines for all tumour types, ESMO organizes consensus conferences to focus on specific issues in each type of tumour. In this setting, a consensus conference on the management of lymphoma was held on 18 June 2011 in Lugano, next to the 11th International Conference on Malignant Lymphoma. The conference convened ∼30 experts from all around Europe, and selected six lymphoma entities to be addressed; for each of them, three to five open questions were to be addressed by the experts. For each question, a recommendation should be given by the panel, referring to the strength of the recommendation based on the level of evidence. This consensus report focuses on the three less common lymphoproliferative malignancies: marginal zone lymphoma, mantle cell lymphoma, and peripheral T-cell lymphomas. A first report had focused on diffuse large B-cell lymphoma, follicular lymphoma, and chronic lymphocytic leukaemia.

Whole genome profiling and other high throughput technologies in lymphoid neoplasms--current contributions and future hopes

The development of high throughput technologies based on the knowledge of the human genome has opened the possibility to search for global genomic alterations in tumors responsible for their development and progression that may have important clinical implications. One of the major applications of this genomic knowledge has been the design of different types of microarray platforms for the analysis of DNA alterations and gene expression profiling (GEP). The main contributions of the DNA studies in lymphoid neoplasms include the definition of relatively characteristic genomic profiles for specific disease entities, the demonstration of common chromosomal alterations across entities, the identification of genes and pathways targeted by the altered chromosomal regions, and the identification of chromosomal alterations with prognostic implications. RNA GEP studies in these tumors have enhanced the molecular characterization of known entities and facilitated the recognition of new subtypes and categories of lymphoid neoplasms, the identification of new biomarkers and prognostic models, and the detection of oncogenic pathways with potential implications for targeted therapies. The recent development of the next generation sequencing (NGS) technologies and its application in lymphoid neoplasms already have provided an initial view of the complex landscape of somatic mutations in these tumors and some findings with important functional and clinical implications. This review addresses the major contributions and limitations of the microarray technologies in the understanding of lymphoid neoplasms and discusses how this knowledge may be transferred into the clinics. The initial results of the NGS studies are also presented.

Peripheral T-cell and NK-cell lymphomas in the WHO classification: pearls and pitfalls

Peripheral T-cell and NK-cell lymphomas are functionally, pathologically, and clinically complex. Most nodal T-cell lymphomas belong to the adaptive immune system, whereas many extranodal T-cell and NK-cell lymphomas are derived from innate immune cells. The pathological manifestations often reflect the functional attributes of the neoplastic cells. Several forms of peripheral T-cell lymphoma are derived from T-follicular helper cells (T(FH)), and include angioimmunoblastic T-cell lymphoma, the follicular variant of peripheral T-cell lymphoma, not otherwise specified, and primary cutaneous small/medium CD4-positive T-cell lymphoma. T(FH)-derived neoplasms are often associated with atypical and clonal B-cell proliferations, which take a number of forms, sometimes mimicking classical Hodgkin's lymphoma, and sometimes showing marked plasmacytic differentiation. Most extranodal T-cell lymphomas are cytotoxic and often arise in mucosal-associated sites. They can be derived from either αβ or γδ cytotoxic T cells, and include subcutaneous panniculitis-like T-cell lymphoma, and enteropathy-associated T-cell lymphomas, both Type I and Type II. Type I enteropathy-associated lymphomas occur in association with celiac disease, whereas Type II lymphomas are more often sporadic. For some T-cell lymphomas, such as hepatosplenic T-cell lymphoma, immunophenotypic heterogeneity is seen within a single disease entity. New data are emerging on the molecular pathogenesis of T-cell and NK-cell lymphoma, but most tumor types remain poorly characterized.

New molecular insights into peripheral T cell lymphomas

Peripheral T cell lymphomas (PTCLs) are heterogeneous neoplasms and represent about 12% of all lymphoid malignancies. They are often regarded as "orphan diseases," a designation that does not reflect their real incidence but rather signifies the difficulties encountered in their classification, diagnosis, and treatment. Here we revise the current understanding of the pathobiological characteristics of the most common nodal PTCLs by focusing on the contribution given by high-throughput technologies and the identification of potential therapeutic targets proposed by translational studies.

BCL10 down-regulation in peripheral T-cell lymphomas

The BCL10 gene encodes for a T-cell receptor signaling downstream protein involved in nuclear factor κB activation. It is expressed in normal lymphoid tissues and in several B-non Hodgkin lymphomas, its aberrant function being related to the pathogenesis of certain subtypes. Conversely, conflicting data are available concerning BCL10 expression in peripheral T cell lymphomas. We analyzed BCL10 expression in peripheral T cell lymphomas and correlated it with NFκB activation, proliferation, phenotypic aberration, and survival. First, gene expression analysis of 40 peripheral T cell lymphomas (28 peripheral T cell lymphomas/not otherwise specified, 6 anaplastic large cell lymphomas, and 6 angioimmunoblastic lymphomas), 4 reactive lymph nodes, and 20 samples of normal T-lymphocytes, showed significantly lower BCL10 gene expression in all tumors in comparison to normal samples, the lowest values being detected in anaplastic large cell lymphoma. Secondly, we studied the immunohistochemical expression of BCL10 in 52 peripheral T cell lymphomas/not otherwise specified on tissue microarrays. BCL10 was expressed in 10/52 cases (19%), not showing any significant correlation with either expression of Ki-67 and the T-cell markers or NFκB activation. Furthermore, BCL10 expression was not associated with peculiar gene expression profiles. Finally, we did not find significant correlations with progression free survival and overall survival, although a favorable trend was recorded in BCL10(+) cases. In conclusion, BCL10 was commonly down-regulated in peripheral T cell lymphomas, suggest the T-cell receptor signaling cascade for future characterization.

Peripheral T-cell Lymphoma with Cyclin D1 overexpression: a case report

Peripheral T-cell lymphomas not otherwise specified are generally considered aggressive non-Hodgkin lymphomas, because of poor natural outcome and response to therapy. They show a complex karyotype without any specific genetic hallmark. We report a case of peripheral T-cell lymphoma not otherwise specified with heterogeneous nuclear Cyclin D1 immunohistochemical overexpression, due to gene copy gain, a phenomenon similar to that observed in Mantle Cell Lymphoma characterized by t(11;14)(q13;q32). In this case report we underline the diagnostic pitfall rapresented by Cyclin D1 immunoistochemical overexpression in a T-cell lymphoma. Several pitfalls could lead to misinterpretation of diagnosis, therefore, we underlined the need to integrate the classical histology and immunohistochemistry with molecular tests as clonality or Fluorescence in situ hybridization.

Tricky and Terrible T-Cell Tumors: These are Thrilling Times for Testing: Molecular Pathology of Peripheral T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCLs) encompass a group of rare and usually clinically aggressive diseases. The classification and diagnosis of these diseases are compounded by their marked pathological heterogeneity and complex clinical features. With the exception of ALK-positive anaplastic large cell lymphoma (ALCL), which is defined on the basis of ALK rearrangements, genetic features play little role in the definition of other disease entities. In recent years, hitherto unrecognized chromosomal translocations have been reported in small subsets of PTCLs, and genome-wide array-based profiling investigations have provided novel insights into their molecular characteristics. This article summarizes the current knowledge on the best-characterized genetic and molecular alterations underlying the pathogenesis of PTCLs, with a focus on recent discoveries, their relevance to disease classification, and their management implications from a diagnostical and therapeutical perspective.

Identification and characterization of peripheral T-cell lymphoma-associated SEREX antigens

Peripheral T-cell lymphomas (PTCL) are generally less common and pursue a more aggressive clinical course than B-cell lymphomas, with the T-cell phenotype itself being a poor prognostic factor in adult non-Hodgkin lymphoma (NHL). With notable exceptions such as ALK⁺ anaplastic large cell lymphoma (ALCL, ALK+), the molecular abnormalities in PTCL remain poorly characterised. We had previously identified circulating antibodies to ALK in patients with ALCL, ALK⁺. Thus, as a strategy to identify potential antigens associated with the pathogenesis of PTCL, not otherwise specified (PTCL, NOS), we screened a testis cDNA library with sera from four PTCL, NOS patients using the SEREX (serological analysis of recombinant cDNA expression libraries) technique. We identified nine PTCL, NOS-associated antigens whose immunological reactivity was further investigated using sera from 52 B- and T-cell lymphoma patients and 17 normal controls. The centrosomal protein CEP250 was specifically recognised by patients sera and showed increased protein expression in cell lines derived from T-cell versus B-cell malignancies. TCEB3, BECN1, and two previously uncharacterised proteins, c14orf93 and ZBTB44, were preferentially recognised by patients' sera. Transcripts for all nine genes were identified in 39 cancer cell lines and the five genes encoding preferentially lymphoma-recognised antigens were widely expressed in normal tissues and mononuclear cell subsets. In summary, this study identifies novel molecules that are immunologically recognised in vivo by patients with PTCL, NOS. Future studies are needed to determine whether these tumor antigens play a role in the pathogenesis of PTCL.

Pathology and biology of peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) represent a heterogeneous group of more than 20 neoplastic entities derived from mature T cells and natural killer (NK) cells involved in innate and adaptive immunity. With few exceptions these malignancies, which may present as disseminated, predominantly extranodal or cutaneous, or predominantly nodal diseases, are clinically aggressive and have a dismal prognosis. Their diagnosis and classification is hampered by several difficulties, including a significant morphological and immunophenotypic overlap across different entities, and the lack of characteristic genetic alterations for most of them. Although there is increasing evidence that the cell of origin is a major determinant for the delineation of several PTCL entities, however, the cellular derivation of most entities remains poorly characterized and/or may be heterogeneous. The complexity of the biology and pathophysiology of PTCLs has been only partly deciphered. In recent years, novel insights have been gained from genome-wide profiling analyses. In this review, we will summarize the current knowledge on the pathobiological features of peripheral NK/T-cell neoplasms, with a focus on selected disease entities manifesting as tissue infiltrates primarily in extranodal sites and lymph nodes.