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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.

PTCL patients exhibit poor survival with existing treatments. We investigated the efficacy of CHOP combined with alemtuzumab in 116 PTCL patients age 61-80 in an open-label, randomized phase 3 trial. Alemtuzumab was given on day 1, to a total of 360 mg in 21 patients, or 120 mg in 37. Hematotoxicity was increased with A-CHOP resulting in more grade ≥3 infections (40% versus 21%) and 4 versus 1 death due to infections, respectively. CR/CRu rate was 60% for A-CHOP and 43% for CHOP, and OR rate was 72% and 66%, respectively. Three-year-EFS, PFS and OS were 27% [15%-39%], 28% [15%-40%], and 37% ([23%-50%] for A-CHOP, and 24% [12%-35%], 29% [17%-41%], and 56% [44%-69%] for CHOP, respectively, showing no significant differences. Multivariate analyses, adjusted for strata and sex confirmed these results (hazard ratio HR EFS : 0.7 ([95% CI: 0.5-1.1]; p = 0.094), HR PFS : 0.8 ([95% CI: 0.5-1.2]; p = 0.271), HR OS : 1.4 ([95% CI: 0.9-2.4]; p = 0.154). The IPI score was validated, and male sex (HR EFS 2.5) and bulky disease (HR EFS 2.2) were significant risk factors for EFS, PFS, and OS. Alemtuzumab added to CHOP increased response rates, but did not improve survival due to treatment-related toxicity.

Myeloid and lymphoid malignancies are postulated to have distinct pathogenetic mechanisms. The recent observation that patients with a myeloproliferative neoplasm have an increased risk of developing lymphoproliferative malignancy has challenged this assumption. We collected a nationwide cohort of patients with both malignancies. Patients diagnosed in 1990-2015 were identified through the national Danish Pathology Registry. We identified 599 patients with myeloproliferative neoplasm and a concomitant or subsequent diagnosis of lymphoma. Histopathological review of the diagnostic samples from each patient led to a final cohort of 97 individuals with confirmed dual diagnoses of myeloproliferative neoplasm and lymphoma. The age range at diagnosis was 19-94 years (median: 71 years). To avoid the inclusion of cases of therapy-induced myeloproliferative neoplasm occurring in patients previously treated for lymphoma, only patients with myeloproliferative neoplasm diagnosed unequivocally before the development of lymphoma were included. The average time interval between the diagnoses of the two malignancies was 1.5 years. In the majority of patients (90%) both diagnoses were established within 5 years from each other. Among the lymphoma entities, the frequency of peripheral T-cell lymphomas was markedly increased. Interestingly, all but one of the T-cell lymphomas were of angioimmunoblastic type. These findings suggest that myeloproliferative neoplasm and lymphoproliferative malignancy developing in the same patient may have common pathogenetic events, possibly already at progenitor level. We believe that the molecular characterization of the newly developed biorepository will help to highlight the mechanisms driving the genesis and clonal evolution of these hematopoietic malignancies.

Galectin-1 (Gal-1) has been associated with adverse prognosis in several cancers including lymphoma entities with CD30 expression. However, Gal-1 expression has not been systematically assessed in peripheral T-cell lymphomas (PTCL). Specimens from 169 nodal PTCL were assessed for intratumoural Gal-1 expression by immunohistochemistry. Overall survival (OS) in groups exhibiting high and low Gal-1 expression was compared in the cohort and in a subset analysis of CD30-positive PTCL only. Gal-1 expression was also correlated with biomarkers of the tumour microenvironment. No significant difference in OS based on Gal-1 expression was observed in the entire PTCL cohort. However, in the CD30-positive cohort, patients with high Gal-1 levels had significantly poorer outcome (5 years OS 10%, 95% confidence interval CI, 1-36) than their low Gal-1 counterparts (5 years OS 48%, 95% CI, 30-64, P = .021). In univariate analyses age 60 or younger, non-elevated lactate dehydrogenase (LDH), and performance score less than 2 correlated with superior survival but high Gal-1 expression significantly predicted adverse outcome at both univariate (HR 2.5, 95% CI, 1.1-5.7, P = .026) and multivariate levels (HR 3.2, 95% CI, 1.2-8.5, P = .017). Tumours with high Gal-1 had few cytotoxic T cells in the tumour microenvironment. High intratumoural Gal-1 expression before therapeutic intervention correlates with adverse outcome in nodal CD30 + , ALK - PTCL patients., (© 2019 John Wiley & Sons Ltd.)

Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of mature T-cell malignancies; approximately one-third of cases are designated as PTCL-not otherwise specified (PTCL-NOS). Using gene-expression profiling (GEP), we have previously defined 2 major molecular subtypes of PTCL-NOS, PTCL-GATA3 and PTCL-TBX21, which have distinct biological differences in oncogenic pathways and prognosis. In the current study, we generated an immunohistochemistry (IHC) algorithm to identify the 2 subtypes in paraffin tissue using antibodies to key transcriptional factors (GATA3 and TBX21) and their target proteins (CCR4 and CXCR3). In a training cohort of 49 cases of PTCL-NOS with corresponding GEP data, the 2 subtypes identified by the IHC algorithm matched the GEP results with high sensitivity (85%) and showed a significant difference in overall survival (OS) (P = .03). The IHC algorithm classification showed high interobserver reproducibility among pathologists and was validated in a second PTCL-NOS cohort (n = 124), where a significant difference in OS between the PTCL-GATA3 and PTCL-TBX21 subtypes was confirmed (P = .003). In multivariate analysis, a high International Prognostic Index score (3-5) and the PTCL-GATA3 subtype identified by IHC were independent adverse predictors of OS (P = .0015). Additionally, the 2 IHC-defined subtypes were significantly associated with distinct morphological features (P < .001), and there was a significant enrichment of an activated CD8+ cytotoxic phenotype in the PTCL-TBX21 subtype (P = .03). The IHC algorithm will aid in identifying the 2 subtypes in clinical practice, which will aid the future clinical management of patients and facilitate risk stratification in clinical trials.

Peripheral T-cell lymphoma (PTCL) is a group of complex clinicopathological entities, often associated with an aggressive clinical course. Angioimmunoblastic T-cell lymphoma (AITL) and PTCL-not otherwise specified (PTCL-NOS) are the 2 most frequent categories, accounting for >50% of PTCLs. Gene expression profiling (GEP) defined molecular signatures for AITL and delineated biological and prognostic subgroups within PTCL-NOS (PTCL-GATA3 and PTCL-TBX21). Genomic copy number (CN) analysis and targeted sequencing of these molecular subgroups revealed unique CN abnormalities (CNAs) and oncogenic pathways, indicating distinct oncogenic evolution. PTCL-GATA3 exhibited greater genomic complexity that was characterized by frequent loss or mutation of tumor suppressor genes targeting the CDKN2A /B - TP53 axis and PTEN -PI3K pathways. Co-occurring gains/amplifications of STAT3 and MYC occurred in PTCL-GATA3. Several CNAs, in particular loss of CDKN2A, exhibited prognostic significance in PTCL-NOS as a single entity and in the PTCL-GATA3 subgroup. The PTCL-TBX21 subgroup had fewer CNAs, primarily targeting cytotoxic effector genes, and was enriched in mutations of genes regulating DNA methylation. CNAs affecting metabolic processes regulating RNA/protein degradation and T-cell receptor signaling were common in both subgroups. AITL showed lower genomic complexity compared with other PTCL entities, with frequent co-occurring gains of chromosome 5 (chr5) and chr21 that were significantly associated with IDH2 R172 mutation. CN losses were enriched in genes regulating PI3K-AKT-mTOR signaling in cases without IDH2 mutation. Overall, we demonstrated that novel GEP-defined PTCL subgroups likely evolve by distinct genetic pathways and provided biological rationale for therapies that may be investigated in future clinical trials., (© 2019 by The American Society of Hematology.)

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., (© 2018 by The American Society of Hematology.)

Recognizing the significant biological and clinical heterogeneity of mature T cell and natural killer (NK)/T cell lymphomas, the American Society for Blood and Marrow Transplantation invited experts to develop clinical practice recommendations related to the role of autologous hematopoietic cell transplantation (auto-HCT) and allogeneic HCT (allo-HCT) for specific histological subtypes. We used the GRADE methodology to aid in moving from evidence to decision making and ultimately to generating final recommendations. Auto-HCT in front-line consolidation is recommended in peripheral T cell lymphoma not otherwise specified (PTCL-NOS), angioimmunoblastic T cell lymphoma (AITL), anaplastic large cell lymphoma-anaplastic lymphoma kinase (ALCL-ALK)-negative, NK/T cell (disseminated), enteropathy-associated T cell lymphoma (EATL), and hepatosplenic lymphomas. Auto-HCT in relapsed-sensitive disease is recommended for NK/T cell (localized and disseminated), EATL, subcutaneous panniculitis-like T cell, and ALCL-ALK-positive lymphomas. Auto-HCT is also recommended for PTCL-NOS, AITL, and ALCL-ALK-negative lymphomas if not performed as front-line therapy. Auto-HCT in refractory (primary or relapsed) disease is not recommended for any of the histological subtypes discussed. Allo-HCT in front-line consolidation is recommended for NK/T cell (disseminated), adult T cell leukemia/lymphoma (ATLL; acute and lymphoma type), and hepatosplenic lymphomas. Allo-HCT for relapsed-sensitive disease is recommended for PTCL-NOS, AITL, ALCL-ALK-negative, ALCL-ALK-positive, NK/T cell (localized and disseminated), ATLL (acute, lymphoma type, smoldering/chronic), mycosis fungoides/Sezary syndrome (advanced stage IIB-IVB or tumor stage/extracutaneous), EATL, subcutaneous panniculitis-like T cell, and hepatosplenic lymphoma. Allo-HCT in refractory (primary or relapsed refractory) disease is recommended for any aforementioned histological subtypes. Emerging novel therapies will likely be incorporated into the pretransplantation, peritransplantation, and post-transplantation algorithms (auto-HCT or allo-HCT) with the goals of optimizing efficacy and improving outcomes. We acknowledge that there are unique clinical scenarios not covered by these recommendations that may require individualized decisions., (Copyright © 2017 The American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

Clinical trials (CTs) are needed to improve the outcome for peripheral T-cell lymphomas (PTCL), and accrual into CTs is one of the main recommendations in international treatment guidelines. The use of risk-adapted strategies has been suggested as a way to optimize treatment outcome in PTCL. The aim of the present study was to evaluate CT eligibility and selected prognostic indices in a population-based PTCL cohort of 481 PTCL patients identified from the Danish Lymphoma Registry in the period 2000-2010. According to five predefined parameters (age, performance status, P-creatinine, P-ALAT and measurable tumour lesion), patients were subdivided into four groups: 'younger fit', 'elderly fit', 'frail' and 'not CT eligible'. International prognostic index (IPI), prognostic index for T-cell lymphoma (PIT) and anaplastic lymphoma kinase (ALK) protein expression were tested at subtype-specific level. Overall, 41% of the patients were considered eligible for interventional CTs implicating curatively intended multiagent chemotherapy, including, if considered appropriate, consolidating stem cell transplantation (SCT), as part of the upfront management strategy. Moreover, 28% was elderly fit and eligible for interventional CT, including those with SCT as part of the trial design. Approximately 7% were defined as 'too frail' for aggressive treatment schedules, whereas 24% were deemed not to be eligible for any CT. Both overall and progression-free survivals were effectively predicted by IPI and PIT (p < 0.001). ALK-positive anaplastic large cell lymphoma patients were significantly younger (median age 40 vs. 62, p < 0.001) and had a better outcome than their ALK-negative counterparts (p < 0.001). However, ALK expression lost its prognostic significance when adjusting for age. In a population-based cohort of adult Caucasian PTCL patients, approximately half were eligible for multiagent chemotherapy with or without consolidating SCT. Both IPI and PIT are useful prognostic indices in all 'primary nodal' PTCL entities. The prognostic value of ALK protein expression in anaplastic large cell lymphoma is significantly downsized when adjusting for age., (Copyright © 2014 John Wiley & Sons, Ltd.)

Peripheral T-cell lymphoma (PTCL) represents a relatively rare group of heterogeneous non-Hodgkin lymphomas with a very poor prognosis. Current therapies, based on historical regimens for aggressive B-cell lymphomas, have resulted in insufficient patient outcomes. The majority of patients relapse rapidly, and current 5-year overall survival rates are only 10-30%. It is evident that new approaches to treat patients with PTCL are required. In recent years, prospective studies in PTCL have been initiated, mainly in patients with relapsed/refractory disease. In some of these, selected histologic subtypes have been evaluated in detail. As a consequence, numerous new therapies have been developed and shown activity in PTCL, including: agents targeting the immune system (e.g. brentuximab vedotin, alemtuzumab, lenalidomide); histone deacetylase inhibitors (romidepsin, belinostat); antifolates (pralatrexate); fusion proteins (denileukin diftitox); nucleoside analogs (pentostatin, gemcitabine); and other agents (e.g. alisertib, plitidepsin, bendamustine, bortezomib). A variety of interesting novel combinations is also emerging. It is hoped that these innovative approaches, coupled with a greater understanding of the clinicopathologic features, pathogenesis, molecular biology, and natural history of PTCL will advance the field and improve outcomes in this challenging group of diseases. This review summarizes the currently available clinical evidence on the various approaches to treating relapsed/refractory PTCL, including the role of stem cell transplantation, with an emphasis on potential new drug therapies., (Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.)

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.

Purpose: Systemic peripheral T-cell lymphomas (PTCLs) respond poorly to conventional therapy. To evaluate the efficacy of a dose-dense approach consolidated by up-front high-dose chemotherapy (HDT) and autologous stem-cell transplantation (ASCT) in PTCL, the Nordic Lymphoma Group (NLG) conducted a large prospective phase II study in untreated systemic PTCL. This is the final report, with a 5-year median follow-up, of the NLG-T-01 study., Patients and Methods: Treatment-naive patients with PTCL age 18 to 67 years (median, 57 years) were included. Anaplastic lymphoma kinase (ALK) -positive anaplastic large-cell lymphoma (ALCL) was excluded. An induction regimen of six cycles of biweekly CHOEP (cyclophosphamide, doxorubicin, vincristine, etoposide, and prednisone) was administered (in patients age > 60 years, etoposide was omitted). If in complete or partial remission, patients proceeded to consolidation with HDT/ASCT., Results: Of 166 enrolled patients, 160 had histopathologically confirmed PTCL. The majority presented with advanced-stage disease, B symptoms, and elevated serum lactate dehydrogenase. A total of 115 underwent HDT/ASCT, with 90 in complete remission at 3 months post-transplantation. Early failures occurred in 26%. Treatment-related mortality was 4%. At 60.5 months of median follow-up, 83 patients were alive. Consolidated 5-year overall and progression-free survival (PFS) were 51% (95% CI, 43% to 59%) and 44% (95% CI, 36% to 52%), respectively. Best results were obtained in ALK-negative ALCL., Conclusion: Dose-dense induction followed by HDT/ASCT was well tolerated and led to long-term PFS in 44% of treatment-naive patients with PTCL. This represents an encouraging outcome, particularly considering the high median age and adverse risk profile of the study population. Therefore, dose-dense induction and HDT/ASCT are a rational up-front strategy in transplantation-eligible patients with PTCL.

The efficacy and safety of zanolimumab (HuMax-CD4) in patients with relapsed or refractory peripheral T Cell lymphoma (PTCL) was evaluated. Twenty-one adult patients with relapsed or refractory CD4(+) PTCL of non-cutaneous type (angioimmunoblastic T cell lymphoma (AITL) n = 9, PTCL-not otherwise specified (NOS) n = 7, anaplastic large cell lymphoma (ALCL) n = 4 and enteropathy type T cell lymphoma n = 1) were treated in a single-arm multi-centre study, with weekly intravenous infusions of zanolimumab 980 mg for 12 weeks. Median age was 69 years (range 26-85). Seventeen of the patients had advanced stage disease (Ann Arbor stages III-IV). Objective tumour responses were obtained in 24% of the patients with two complete responses unconfirmed (CRu) and three partial responses (PR). One of the CRus lasted more than 252 d. Responses were obtained in different PTCL entities: AITL (n = 3), ALCL (n = 1) and PTCL-NOS (n = 1). In general, the trial drug was well tolerated with no major toxicity. Zanolimumab at a dose of 980 mg weekly demonstrated clinical activity and an acceptable safety profile in this poor-prognosis patient population, suggesting that the potential benefit combining zanolimumab with standard chemotherapy in the treatment of PTCL should be investigated.

The aim of the study was to investigate the expression of angio- and lymphangiogenic molecules (vascular endothelial growth factors VEGF and VEGF-C and their receptors Flt-1, KDR, and Flt-4) in non-Hodgkin lymphomas (NHL) treated in the pre-rituximab era. Pre-therapeutic lymph-node biopsies from 155 patients with NHL (64 follicular lymphomas (FLs), 47 de novo diffuse large B-cell lymphomas (DLBCL) and 44 peripheral T-cell lymphomas (PTCL)) were stained by in situ hybridization and immunohistochemistry. Tumor cell expression of VEGF, VEGF-C and their receptors was detected in most of the analyzed biopsies. In FL, diffuse intratumoral VEGF staining correlated with shorter overall survival (OS) (p = 0.008) and diffuse KDR staining was associated with a higher risk of histologic transformation (p = 0.05). In DLBCL, high KDR expression predicted poor treatment response (p = 0.03) and had a significant adverse impact on OS (p < 0.001). In PTCL, diffuse tissue distribution of VEGF mRNA correlated with an unfavorable 5-year OS (p = 0.004).

The aim of the study was to evaluate angiogenesis in different subtypes of non-Hodgkin's lymphoma (NHL) and to correlate angiogenic scores to clinical endpoints. Pre-therapeutic lymph node biopsies from 308 patients with NHL [107 follicular B-cell lymphoma (FL), 94 diffuse large B-cell lymphoma (DLBCL), 107 peripheral T-cell lymphoma (PTCL)] were studied. Microvessels were scored according to the Chalkley and microvessel density method (MVD) methods. Vascular endothelial growth factor (VEGF) protein expression was evaluated by immunohistochemistry. Both Chalkley and MVD methods showed, that the lymphoma subtypes differed significantly in angiogenic scores (P < 0.001). Angiogenic scores in tumor area were highest in PTCL, and lowest in FL. However, a remarkable high microvessel density was found in interfollicular areas of FL. In FL, high interfollicular MVD scores predicted progressive disease and poorer overall and event-free survival (P = 0.024 and 0.013). High interfollicular Chalkley scores correlated with transformation to DLBCL (P = 0.01). VEGF expression was detected in all NHL subtype, and the strongest expression was found in PTCL. In FL, patients with diffuse VEGF expression in lymphoma cells had poorer overall survival than those with focal expression.

Peripheral T-cell lymphomas (PTCL) consist of many subtypes with variable clinical presentation. Long-term prognosis of most subtypes is unfavorable and novel therapeutic approaches are needed. This review attempts to summarize what is known on the feasibility and efficacy of high-dose therapy supported by stem cell transplantation (SCT) in PTCL. In patients with relapsed or refractory PTCL, the outcome of autologous SCT (ASCT) seems to be comparable to that of patients with aggressive B-cell lymphomas. Although excellent treatment results have been encountered with ASCT in patients with anaplastic large cell lymphoma (ALCL), the superiority of this approach over chemotherapy alone needs confirmation in randomized studies. In less favorable subtypes (e.g. alk-negative ALCL, PTCL not otherwise specified, enteropathy-associated T-cell lymphoma, and angioimmunoblastic T-cell lymphoma) high-dose consolidation of the first remission should be studied in prospective trials. Minimal experience is currently available on allogeneic SCT in patients with PTCL. Given the high relapse rate after ASCT in high-risk patients and potential for graft-vs.-lymphoma effect, also this approach should be studied. Due to rarity of PTCL, international collaboration is mandatory in order to study the various aspects of SCT in this patient population.