Genome-wide DNA methylation-analysis of blastic plasmacytoid dendritic cell neoplasm identifies distinct molecular features.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) constitutes a rare and aggressive malignancy originating from plasmacytoid dendritic cells (pDCs) with a primarily cutaneous tropism followed by dissemination to the bone marrow and other organs. We conducted a genome-wide analysis of the tumor methylome in an extended cohort of 45 BPDCN patients supplemented by WES and RNA-seq as well as ATAC-seq on selected cases. We determined the BPDCN DNA methylation profile and observed a dramatic loss of DNA methylation during malignant transformation from early and mature DCs towards BPDCN. DNA methylation profiles further differentiate between BPDCN, AML, CMML, and T-ALL exhibiting the most striking global demethylation, mitotic stress, and merely localized DNA hypermethylation in BPDCN resulting in pronounced inactivation of tumor suppressor genes by comparison. DNA methylation-based analysis of the tumor microenvironment by MethylCIBERSORT yielded two, prognostically relevant clusters (IC1 and IC2) with specific cellular composition and mutational spectra. Further, the transcriptional subgroups of BPDCN (C1 and C2) differ by DNA methylation signatures in interleukin/inflammatory signaling genes but also by higher transcription factor activity of JAK-STAT and NFkB signaling in C2 in contrast to an EZH2 dependence in C1-BPDCN. Our integrative characterization of BPDCN offers novel molecular insights and potential diagnostic applications.

Molecularly Stratified Treatment Options in Primary Refractory DLBCL/HGBL with MYC and BCL2 or BCL6 Rearrangements (HGBL, NOS with MYC/BCL6).

BACKGROUND: There is growing evidence supporting multidisciplinary molecular tumor boards (MTB) in solid tumors whereas hematologic malignancies remain underrepresented in this regard. OBJECTIVE: The present study aimed to assess the clinical relevance of MTBs in primary refractory diffuse large B-cell lymphomas/high-grade B-cell lymphomas with MYC and BCL2 rearrangements (prDLBCL/HGBL-MYC/BCL2) (n = 13) and HGBL, not otherwise specified (NOS), with MYC and BCL6 rearrangements (prHGBL, NOS-MYC/BCL6) (n = 6) based on our previously published whole-exome sequencing (WES) cohort. PATIENTS AND METHODS: For genomic analysis, the institutional MTB WES pipeline (University Cancer Center Schleswig-Holstein: UCCSH), certified for routine clinical diagnostics, was employed and supplemented by a comprehensive immunohistochemical work-up. Consecutive database research and annotation according to established evidence levels for molecularly stratified therapies was performed (NCT-DKTK/ESCAT). RESULTS: Molecularly tailored treatment options with NCT-DKTK evidence level of at least m2A were identified in each case. We classified mutations in accordance with biomarker/treatment baskets and detected a heterogeneous spectrum of targetable alterations affecting immune evasion (IE; n = 30), B-cell targets (BCT; n = 26), DNA damage repair (DDR; n = 20), tyrosine kinases (TK; n = 13), cell cycle (CC; n = 7), PI3K-MTOR-AKT pathway (PAM; n = 2), RAF-MEK-ERK cascade (RME; n = 1), and others (OTH; n = 11). CONCLUSION: Our virtual MTB approach identified potential molecularly targeted treatment options alongside targetable genomic signatures for both prDLBCL/HGBL-MYC/BCL2 and prHGBL, NOS-MYC/BCL6. These results underline the potential of MTB consultations in difficult-to-treat lymphomas early in the treatment sequence.

Primary refractory plasmablastic lymphoma: A precision oncology approach.

Introduction: Hematologic malignancies are currently underrepresented in multidisciplinary molecular-tumor-boards (MTB). This study assesses the potential of precision-oncology in primary-refractory plasmablastic-lymphoma (prPBL), a highly lethal blood cancer. Methods: We evaluated clinicopathological and molecular-genetic data of 14 clinically annotated prPBL-patients from initial diagnosis. For this proof-of-concept study, we employed our certified institutional MTB-pipeline (University-Cancer-Center-Schleswig-Holstein, UCCSH) to annotate a comprehensive dataset within the scope of a virtual MTB-setting, ultimately recommending molecularly stratified therapies. Evidence-levels for MTB-recommendations were defined in accordance with the NCT/DKTK and ESCAT criteria. Results: Median age in the cohort was 76.5 years (range 56-91), 78.6% of patients were male, 50% were HIV-positive and clinical outcome was dismal. Comprehensive genomic/transcriptomic analysis revealed potential recommendations of a molecularly stratified treatment option with evidence-levels according to NCT/DKTK of at least m2B/ESCAT of at least IIIA were detected for all 14 prPBL-cases. In addition, immunohistochemical-assessment (CD19/CD30/CD38/CD79B) revealed targeted treatment-recommendations in all 14 cases. Genetic alterations were classified by treatment-baskets proposed by Horak et al. Hereby, we identified tyrosine-kinases (TK; n=4), PI3K-MTOR-AKT-pathway (PAM; n=3), cell-cycle-alterations (CC; n=2), RAF-MEK-ERK-cascade (RME; n=2), immune-evasion (IE; n=2), B-cell-targets (BCT; n=25) and others (OTH; n=4) for targeted treatment-recommendations. The minimum requirement for consideration of a drug within the scope of the study was FDA-fast-track development. Discussion: The presented proof-of-concept study demonstrates the clinical potential of precision-oncology, even in prPBL-patients. Due to the aggressive course of the disease, there is an urgent medical-need for personalized treatment approaches, and this population should be considered for MTB inclusion at the earliest time.

Mutational landscape of high-grade B-cell lymphoma with MYC-, BCL2 and/or BCL6 rearrangements characterized by whole-exome sequencing.

High-grade B-cell lymphoma accompanied with double/triple-hit MYC and BCL2 and/or BCL6 rearrangements (HGBLDH/ TH) poses a cytogenetically-defined provisional entity among aggressive B-cell lymphomas that is traditionally associated with unfavorable prognosis. In order to better understand the mutational and molecular landscape of HGBLDH/ TH we here performed whole-exome sequencing and deep panel next-generation sequencing of 47 clinically annotated cases. Oncogenic drivers, mutational signatures and perturbed pathways were compared with data from follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL). We find an accumulation of oncogenic mutations in NOTCH, IL6/JAK/STAT and NFκB signaling pathways and delineate the mutational relationship within the continuum between FL/DLBCL, HGBL-DH/TH and BL. Further, we provide evidence of a molecular divergence between BCL2 and BCL6 rearranged HGBL-DH. Beyond a significant congruency with the C3/EZB DLBCL cluster in BCL2 rearranged cases on an exome-wide level, we observe an enrichment of the SBS6 mutation signature in BCL6 rearranged cases. Differential gene set enrichment and subsequent network propagation analysis according to cytogenetically defined subgroups revealed an impairment of TP53 and MYC pathway signaling in BCL2 rearranged cases, whereas BCL6 rearranged cases lacked this enrichment, but instead showed impairment of E2F targets. Intriguingly, HGBL-TH displayed intermediate mutational features considering all three aspects. This study elucidates a recurrent pattern of mutational events driving FL into MYC-driven BCL2-rearranged HGBL, unveiling the mutational pathogenesis of this provisional entity. Through this refinement of the molecular taxonomy for aggressive, germinal center-derived B-cell lymphomas, this calls into question the current World Health Organization classification system, especially regarding the status of MYC/BCL6- rearranged HGBL.

Comparative analysis of international prognostic indices in gray-zone lymphoma.

Gray-zone lymphoma (GZL) reflects an aggressive B-cell neoplasm with features intermediate between diffuse large B-cell lymphoma (DLBCL) and classical Hodgkin lymphoma (cHL). The International Prognostic Index (IPI) and its derivatives (R-IPI, NCCN-IPI, and the Hasenclever IPS) have been established for DLBCL or cHL while the most suitable scoring system for GZL remains undetermined. In an exploratory multi-centric cohort of GZL (n = 61), we performed a comparative analysis of prognostic indices with regard to model fit and mutual concordance. The calculation of the corrected Akaike's information criterion (cAIC) and Harrel's concordance index (c-index) for each scoring system identified the NCCN-IPI to harbor the most convincing prognostic capabilities regarding both overall survival (OS) and progression-free survival (PFS) compared to its enhanced derivatives. The current results affirm the clinical utility of the NCCN-IPI and suggest its preferential use in clinical practice in GZL-patients.

Integrative genomic and transcriptomic analysis in plasmablastic lymphoma identifies disruption of key regulatory pathways.

Plasmablastic lymphoma (PBL) represents a clinically heterogeneous subtype of aggressive B-cell non-Hodgkin lymphoma. Targeted-sequencing studies and a single-center whole-exome sequencing (WES) study in HIV-positive patients recently revealed several genes associated with PBL pathogenesis; however, the global mutational landscape and transcriptional profile of PBL remain elusive. To inform on disease-associated mutational drivers, mutational patterns, and perturbed pathways in HIV-positive and HIV-negative PBL, we performed WES and transcriptome sequencing (RNA-sequencing) of 33 PBL tumors. Integrative analysis of somatic mutations and gene expression profiles was performed to acquire insights into the divergent genotype-phenotype correlation in Epstein-Barr virus-positive (EBV+) and EBV- PBL. We describe a significant accumulation of mutations in the JAK signal transducer and transcription activator (OSMR, STAT3, PIM1, and SOCS1), as well as receptor tyrosine-kinase RAS (ERBB3, NRAS, PDGFRB, and NTRK) pathways. We provide further evidence of frequent perturbances of NF-κB signaling (NFKB2 and BTK). Induced pathways, identified by RNA-sequencing, closely resemble the mutational profile regarding alterations accentuated in interleukin-6/JAK/STAT signaling, NF-κB activity, and MYC signaling. Moreover, class I major histocompatibility complex-mediated antigen processing and cell cycle regulation were significantly affected by EBV status. An almost exclusive upregulation of phosphatidylinositol 3-kinase/AKT/mTOR signaling in EBV+ PBL and a significantly induced expression of NTRK3 in concert with recurrent oncogenic mutations in EBV- PBL hint at a specific therapeutically targetable mechanism in PBL subgroups. Our characterization of a mutational and transcriptomic landscape in PBL, distinct from that of diffuse large B-cell lymphoma and multiple myeloma, substantiates the pathobiological independence of PBL in the spectrum of B-cell malignancies and thereby refines the taxonomy for aggressive lymphomas.

Genomic insights into the pathogenesis of Epstein-Barr virus-associated diffuse large B-cell lymphoma by whole-genome and targeted amplicon sequencing.

Epstein-Barr virus (EBV)-associated diffuse large B-cell lymphoma not otherwise specified (DLBCL NOS) constitute a distinct clinicopathological entity in the current World Health Organization (WHO) classification. However, its genomic features remain sparsely characterized. Here, we combine whole-genome sequencing (WGS), targeted amplicon sequencing (tNGS), and fluorescence in situ hybridization (FISH) from 47 EBV + DLBCL (NOS) cases to delineate the genomic landscape of this rare disease. Integrated WGS and tNGS analysis clearly distinguished this tumor type from EBV-negative DLBCL due to frequent mutations in ARID1A (45%), KMT2A/KMT2D (32/30%), ANKRD11 (32%), or NOTCH2 (32%). WGS uncovered structural aberrations including 6q deletions (5/8 patients), which were subsequently validated by FISH (14/32 cases). Expanding on previous reports, we identified recurrent alterations in CCR6 (15%), DAPK1 (15%), TNFRSF21 (13%), CCR7 (11%), and YY1 (6%). Lastly, functional annotation of the mutational landscape by sequential gene set enrichment and network propagation predicted an effect on the nuclear factor κB (NFκB) pathway (CSNK2A2, CARD10), IL6/JAK/STAT (SOCS1/3, STAT3), and WNT signaling (FRAT1, SFRP5) alongside aberrations in immunological processes, such as interferon response. This first comprehensive description of EBV + DLBCL (NOS) tumors substantiates the evidence of its pathobiological independence and helps stratify the molecular taxonomy of aggressive lymphomas in the effort for future therapeutic strategies.

Systemic Inflammation and Tumour-Infiltrating T-Cell Receptor Repertoire Diversity Are Predictive of Clinical Outcome in High-Grade B-Cell Lymphoma with MYC and BCL2 and/or BCL6 Rearrangements.

High-grade B-cell lymphoma, with MYC and BCL2 and/or BCL6 rearrangements (double/triple-hit high grade B-cell lymphoma, HGBL-DH/TH) constitutes a provisional entity among B-cell malignancies with an aggressive behavior and dire prognosis. While evidence for the essential prognostic role of the composition of the tumor-microenvironment (TME) in hematologic malignancies is growing, its prognostic impact in HGBL-DH/TH remains unknown. In this study, we outline the adaptive immune response in a cohort of 47 HGBL-DH/TH and 27 triple-negative diffuse large B-cell lymphoma (tnDLBCL) patients in a large-scale, next-generation sequencing (NGS) investigation of the T-cell receptor (TCR) ß-chain repertoire and supplement our findings with data on the Glasgow-Prognostic Score (GPS) at diagnosis, as a score-derived measure of systemic inflammation. We supplement these studies with an immunophenotypic investigation of the TME. Our findings demonstrate that the clonal architecture of the TCR repertoire of HGBL-DH/TH differs significantly from tnDLBCL. Moreover, several entity-exclusive clonotypes, suggestive of tumor-neoantigen selection are identified. Additionally, both productive clonality and percentage of maximum frequency clone as measures of TCR repertoire diversity and tumor-directed activity of the adaptive immune system had significant impact on overall survival (OS; productive clonality: p = 0.0273; HR: 2.839; CI: 1.124-7.169; maximum productive frequency: p = 0.0307; HR: 2.167; CI: 1.074-4.370) but not PFS (productive clonality: p = 0.4459; maximum productive frequency: p = 0.5567) in HGBL-DH/TH patients, while GPS was a significant predictor of both OS and PFS (OS: p < 0.0001; PFS: p = 0.0002). Subsequent multivariate analysis revealed GPS and the revised international prognostic index (R-IPI) to be the only prognosticators holding significant impact for OS (GPS: p = 0.038; R-IPI: p = 0.006) and PFS (GPS: p = 0.029; R-IPI: p = 0.006) in HGBL-DH/TH. Through the identification of expanded, recurrent and entity-exclusive TCR-clonotypes we provide indications for a distinct subset of tumor-neoantigenic elements exclusively shared among HGBL-DH/TH. Further, we demonstrate an adverse prognostic role for both systemic inflammation and uniform adaptive immune response.

Performance of international prognostic indices in plasmablastic lymphoma: a comparative evaluation.

PURPOSE: Plasmablastic lymphoma (PBL) is a rare and aggressive B-cell malignancy with a heterogenous clinical and prognostic spectrum, determined by multiple factors, including age, HIV- and MYC-status. While there exist several validated scoring systems for diffuse large B-cell lymphoma, which incorporate basic clinical features (age, lactate dehydrogenase, sites of (extranodal) involvement, stage and performance), none of these have been systematically assessed in PBL. METHODS: We determined the (age-adjusted; aa)-International Prognostic Index (IPI), revised IPI (R-IPI), and National Comprehensive Cancer Network IPI (NCCN-IPI) in a comprehensive multi-center cohort (n = 78) of PBL patients. Further, all indices were comparatively investigated for model quality and concordance. RESULTS: Univariate analysis revealed significant prognostic capabilities for all indices, all of which identified a subgroup with favorable outcome. Discriminatory power between patients with less benign prognosis and especially refractory disease exhibited significant variability. Subsequently, stratified models for each risk score were compared employing corrected Akaike's information criterion (cAIC) and Harrel's concordance index (c-index). Here, the NCCN-IPI outperformed both IPI and R-IPI regarding c-index with ambiguous cAIC results, underlining its clinical utility and suggesting it for preferential use in clinical practice. CONCLUSION: Our current observations support the use of the IPI and its enhanced derivatives in PBL patients. There is, however, a distinct requirement for novel prognostic tools to better delineate subgroups at risk for early relapse or refractory disease as well as late relapse. A comprehensive molecular characterization of a clinically annotated cohort of PBL patients is therefore urgently warranted.

Exhaustion of tumour-infiltrating T-cell receptor repertoire diversity is an age-dependent indicator of immunological fitness independently predictive of clinical outcome in Burkitt lymphoma.

Burkitt lymphoma (BL) is an aggressive B-cell-malignancy derived from germinal-centre B-cells. Curative therapy traditionally requires intensive immunochemotherapy. Recently, immuno-oncological approaches, modulating the T-cell tumour response, were approved for the treatment of a variety of malignancies. The architecture of the tumour-infiltrating T-cell receptor (TCR) repertoire in BL remains insufficiently characterized. We therefore performed a large-scale, next-generation sequencing study of the complimentary-determining region (CDR)-3 region of the TCRß chain repertoire in a large cohort of all epidemiological subtypes of BL (n = 82) and diffuse large B-cell lymphoma (DLBCL; n = 34). Molecular data were subsequently assessed for correlation with clinical outcome. Our investigations revealed an age-dependent immunoprofile in BL as in DLBCL. Moreover, we found several public clonotypes in numerous patients suggestive of shared tumour neoantigen selection exclusive to BL and distinct from DLBCL regardless of Epstein-Barr virus and/or human immunodeficiency virus status. Compared with baseline, longitudinal analysis unveiled significant repertoire restrictions upon relapse (P = 0·0437) while productive TCR repertoire clonality proved to be a useful indicator of both overall and progression-free-survival [OS: P = 0·0001; hazard ratio (HR): 6·220; confidence interval (CI): 2·263-11·78; PFS: P = 0·0025; HR: 3·086; CI: 1·555-7·030]. Multivariate analysis confirmed its independence from established prognosticators, including age at diagnosis and comorbidities. Our findings establish the clinical relevance of the architecture and clonality of the TCR repertoire and its age-determined dynamics in BL.

The Glasgow Prognostic Score at Diagnosis Is a Predictor of Clinical Outcome in Patients with Multiple Myeloma Undergoing Autologous Haematopoietic Stem Cell Transplantation.

Background: Immunity and inflammatory response affect the tumour microenvironment and the progression of malignancies. Metabolic and inflammatory parameters and ratios of the peripheral blood correlate with outcome in cancer patients. There exist several established and validated inflammation-based scores of prognostic significances including the Glasgow Prognostic Score (GPS). Methods: In this retrospective, multicentre study, we investigated the prognostic capabilities of baseline GPS in patients with multiple myeloma (MM) undergoing autologous stem cell transplantation as a complementary resource for risk stratification. For GPS calculation, a C-reactive-protein (CRP) value of >10 mg/dL counts as one point and an albumin value of <35 g/L connotes another point, resulting in three different subgroups (group I: 0 points; group II: 1 point; and group III: 2 points). Patients with MM admitted to the participating institutions between January 2010 and July 2018 were screened, and established prognostic scores and ratios were assessed. Characteristics significantly associated with overall survival (OS) or progression-free survival (PFS), upon univariate analysis, were included in a Cox proportional hazards model. Results: Following initial assessment, we identified 224 fully evaluable patients who underwent autologous haematopoietic stem cell transplantation for multiple myeloma. A centralised review of pathology and cytogenetic reports was conducted, and a central hematopathology assessment was performed in 175 of 224 cases (78.1%). Proceeding to high-dose chemotherapy and subsequent autologous stem cell transplantation was the main inclusion criterion for all transplant-eligible patients in the study. The median age at diagnosis was 59 years (range: 35-76 years) with a median follow-up of 76 months. Multivariate analysis revealed neutrophil-platelet score (NPS) (HR = 0.528, 95% CI = 0.284-0.984) and B symptoms at primary diagnosis (HR = 1.838, 95% CI = 1.232-2.740) to be independent predictors of PFS while high-risk cytogenetic changes (HR = 2.358, 95% CI = 1.413-3.934, p = 0.001) could be identified as an independent predictor of OS, and GPS to be the only independent predictor of both OS and PFS (OS: HR = 2.127, 95% CI = 1.431-3.162, p < 0.0001 and PFS: HR = 1.405; 95% CI = 1.058-1.867, p = 0.019). Conclusions: Our data show that baseline GPS correlates with rates of relapse and refractory disease in MM patients undergoing autologous transplantation. In a multivariate analysis, these effects were proven to hold prognostic capabilities beyond and independent from established prognosticators. These results require further validation in a prospective setting.

The South Asian Healthy Lifestyle Intervention (SAHELI) trial: Protocol for a mixed-methods, hybrid effectiveness implementation trial for reducing cardiovascular risk in South Asians in the United States.

Intensive lifestyle interventions targeting diet and physical activity are recommended for reducing atherosclerotic cardiovascular disease (ASCVD) risk in adults. However, existing interventions often do not reach immigrant populations because of a mismatch between the social, cultural, and environmental context of immigrants and Western bio behavioral models which underpin evidence-based lifestyle interventions. The South Asian Healthy Lifestyle Intervention (SAHELI) study is a type 1 hybrid design randomized controlled trial aimed at reducing ASCVD risk in South Asian Americans, a group at higher ASCVD risk than whites and other Asian Americans. The objective is to evaluate the clinical effectiveness and implementation potential of a community-based, culturally-adapted lifestyle intervention for South Asian adults. Participants (n = 550) will be randomized to printed healthy lifestyle education materials or SAHELI, a group-based lifestyle change program that includes weekly classes for 16 weeks and 4 booster classes though month 11. SAHELI integrates evidence-based behavior change strategies with culturally-adapted strategies and group motivational interviewing to improve diet, physical activity, and stress management. Follow-up assessments will occur at 6 and 12 months. We hypothesize that the SAHELI intervention group will have greater improvements in clinical ASCVD risk factors (weight, blood pressure, glycated hemoglobin, and lipids), physical activity, and psychosocial outcomes than the print material group at 6- and 12- months. We will use mixed-methods to examine SAHELI's potential for reach, adoption, implementation, and maintenance from the perspective of multiple stakeholders. This study offers the potential to increase the reach and effectiveness of evidence-based lifestyle interventions for South Asian adults at increased risk for ASCVD.

Impact of treatment variability and clinicopathological characteristics on survival in patients with Epstein-Barr-Virus positive diffuse large B cell lymphoma.

Patients with EBV-positive diffuse large B cell lymphoma not otherwise specified (EBV+ DLBCL (NOS)) recurrently present with advanced age and reduced performance status. They are therefore insufficiently represented in clinical trials and treatment is likely to differ. Here we assess clinicopathological characteristics, therapeutic variability and clinical outcome in the largest consecutively diagnosed EBV+ DLBCL (NOS) cohort published to date (n = 80; median age 70 years; range 19-90). Centralized and systematic haematopathological panel review was performed. By immunohistochemistry 60/80 patients were CD30-positive. Further, we identified nine EBV+ DLBCL (NOS) patients with associated or composite peripheral T cell lymphoma at diagnosis or relapse (preceded by clonal T cell populations within the initial DLBCL biopsy in 4/5 cases). Most patients (80%) were treated with R-CHOP-type therapy and 16 patients received none or less intensiveprotocols. Upon univariate analysis both R-CHOP-type therapy (OS: P < 0.0001; PFS: P = 0.0617) and negativity for CD30 (OS: P = 0.0002; PFS: P = 0.0002) showed a protective 66 effect, maintained upon multivariate analysis. In a propensity-score matched analysis with a cohort of non-EBV+ DLBCL (NOS) patients, balanced for all revised-international prognostic index factors, we found an EBV-association to hold no significant impact on progression-free and overall survival whilst exhibiting a trend favouring EBV-negativity (OS: P = 0.116; PFS: P = 0.269). Our findings provide insight into the clinical course of EBV+ DLBCL (NOS), highlight the ramifications of CD30-expression and underline the superior therapeutic efficacy of R-CHOP immunochemotherapy. Alternative therapies, incorporating tumour biology (e.g. CD30 directed therapies) need to be explored in EBV+ DLBCL (NOS) patients. Moreover our data advert to the close relationship between EBV+ DLBCL (NOS) and peripheral T cell lymphomas.

Indolent lymphoma with composite histology and simultaneous transformation at initial diagnosis exhibit clinical features similar to de novo diffuse large B-cell lymphoma.

While various studies characterized clinical and prognostic properties of de novo diffuse large B-Cell lymphoma (DLBCL) and transformed indolent lymphomas, the clinicopathological features of indolent lymphoma and simultaneous secondary transformation upon initial diagnosis (ssDLBCL) are insufficiently established. Between 2010 and 2017, 247 consecutive patients admitted to our institution and treated for DLBCL were investigated for composite histology of ssDLBCL-type. Upon systematical histopathological evaluation composite histology was identified in 22/247 cases (8.9%). The predominant histology of the underlying indolent lymphoma was follicular lymphoma of variable grading (I-IIIA; 81.8%) whereas marginal zone lymphoma represented a minor sub group (18.2%). Clinicopathological investigation revealed a high degree of concordance between ssDLBCL and de novo DLBCL upon initial diagnosis and clinical courses were shown to be strikingly similar. The predominant fraction of ssDLBCL were germinal center derived lymphomas (GCB-type) with a trend towards a superior outcome compared with non-GCB-type ssDLBCL. Additionally, we demonstrate a significant adverse prognostic impact of an underlying indolent lymphoma component other than follicular-type lymphoma (e.g. marginal zone lymphoma). Moreover, the frequency of double-hit (DHL) or double-expressor lymphomas (DEL) appears to be low. Our findings provide substantial insight into the behavior of ssDLBCL, highlight the ramifications of the concurrent high-grade fraction within indolent lymphomas and underline therapeutic efficacy of R-CHOP type immunochemotherapy in the majority of ssDLBCL patients.