Biological characterization of adult MYC-translocation-positive mature B-cell lymphomas other than molecular Burkitt lymphoma

Diffuse large B cell lymphoma (DLBCL): epidemiology, pathophysiology, risk stratification, advancement in diagnostic approaches and prospects: narrative review

Diffuse large B-cell lymphoma (DLBCL) is an aggressive subtype of non-Hodgkin's lymphoma that arises from the germinal center. It represents a heterogeneous disease characterized by different pathological, clinical, and molecular entities. Gene expression profiling based on the alleged cell of origin differentiates transcriptional subtypes such as germinal center and activated B cell-like. DLBCL accounts for around 40% of all non-Hodgkin's lymphomas worldwide. Its incidence generally increases with age. The international prognostic index remains the most important tool for disease stratification.The diagnosis of DLBCL is best made through an excisional biopsy of a suspicious lymph node. Nowadays, advanced techniques are employed to accurately diagnose and determine the clinical outcomes of patients. Immunohistochemistry, next-generation sequencing, and array-based comparative hybridization facilitate the global identification of diverse and numerous genetic alterations. However, further validation should be necessary to apply advanced techniques in clinical practice. In this review, we summarize the current literature and discuss the pathophysiology, epidemiology, and diagnostic advancements of DLBCL.

High-grade B-cell lymphomas: Double hit and non-double hit

The classification of high-grade B-cell lymphoma (HGBL) has continuously evolved over past decades. These neoplasms, as currently defined, represent about 2% of all non-Hodgkin lymphomas and patients with these neoplasms are often refractory or relapsed following standard therapy. The 5th edition of the World Health Organization classification of hematologic neoplasms (WHO-HAEM5) has refined the classification of HGBL and recognizes two types: (1) Diffuse large B-cell lymphoma (DLBCL)/HGBL with MYC and BCL2 rearrangements, with or without BCL6 rearrangements; and (2) HGBL, not otherwise specified (HGBL-NOS). WHO-HAEM5 excluded DLBCL/HGBL with concurrent MYC and BCL6 rearrangements from this category and reclassified them into DLBCL or HGBL-NOS categories respectively based on morphology. The International Consensus Classification (ICC) takes a slightly different approach. In addition to recognizing the two WHO-HAEM5 categories, they recognize HGBL with concurrent MYC and BCL6 rearrangements as a provisional entity. In this review, we provide an update of HGBL and its subgroups, focusing on their clinicopathologic features, diagnosis, molecular genetic features, and pathogenesis. Our diagnostic approach and caveats for differential diagnosis are also discussed with an emphasis on the differential diagnosis with B lymphoblastic leukemia/lymphoma.

Diffuse Large B-Cell Lymphoma/High-Grade B-Cell Lymphoma With MYC and BCL6 Rearrangements: A Study of 60 Cases

Classification of cases of diffuse large B-cell lymphoma (DLBCL)/high-grade B-cell lymphoma (HGBL) with MYC and BCL6 rearrangements, referred to here as BCL6 double-hit lymphoma (DHL), is controversial. We assessed 60 cases of BCL6-DHL and compared this cohort to 224 cases of DHL with MYC and BCL2 rearrangements (BCL2-DHL) and 217 cases of DLBCL not otherwise specified. Compared with the DLBCL cohort, patients with BCL6-DHL had more aggressive clinical features such as frequent extranodal involvement, high-stage disease, a high International Prognostic Index score, and an elevated serum lactate dehydrogenase level (P < .01 for all). Compared with the BCL2-DHL cohort, patients with BCL6-DHL had similarly aggressive clinical features but a lower frequency of germinal center B-cell (GCB) immunophenotype and MYC and BCL2 double expression. Patients with BCL6-DHL showed overall survival (OS) intermediate between patients with DLBCL and BCL2-DHL. Following induction with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemotherapy, patients with BCL6-DHL demonstrated poor OS similar to patients with BCL2-DHL and worse OS than that of patients with DLBCL (P = .024). However, among patients who received rituximab, etoposide phosphate, prednisone, vincristine, cyclophosphamide, and doxorubicin (R-EPOCH), there was no significant difference in OS among the 3 groups (P = .146). Gene expression profiling showed that 60% of BCL6-DHL cases had a double-hit (DH)-like signature compared with 10% of DLBCL-GCB and 93% of BCL2-DHL cases. The DH-like signature in BCL6-DHL cases was associated with a GCB immunophenotype. Based on these data, we suggest that BCL6-DHL cases are clinically more aggressive than DLBCL and patients may benefit from a more aggressive therapy than R-CHOP. The data also suggest that BCL6-DHL, as currently defined, is heterogeneous and that neoplasms with a GCB immunophenotype are more likely to have a DH-like signature and behave more aggressively. Last, we suggest that BCL6-DHL cases deserve to be recognized separately in a lymphoma classification to facilitate further understanding of these neoplasms and for optimal patient management.

Assessment for 11q and other chromosomal aberrations in large B-cell/high-grade B cell lymphomas of germinal center phenotype lacking BCL2 expression

The WHO classifications of hematolymphoid malignancies have recognized several distinct entities within the large B cell lymphomas, including the more recently described high-grade B cell lymphoma with 11q aberration (HGBCL-11q). We utilized genomic array to assess for chromosome 11q abnormalities in a broad set of aggressive B cell lymphomas from 27 patients with a focus on younger adults. The findings suggest more frequent alterations of 11q in diffuse large B cell lymphoma (DLBCL)/HGBCL-GC BCL2-, in comparison to cases of Burkitt lymphoma (BL) or DLBCL-GC BCL2+, and confirm a low genomic complexity score of BL. Variability identified in patterns of 11q alterations suggests genomic array studies may afford value over FISH testing as we continue to understand HGBCL-11q as a distinct entity, and interrogate cases of DLBCL/HGBCL-GC BCL2-.

Aggressive B-cell non-Hodgkin lymphomas: a report of the lymphoma workshop of the 20th meeting of the European Association for Haematopathology

Aggressive B-cell non-Hodgkin lymphomas are a heterogeneous group of diseases and our concepts are evolving as we learn more about their clinical, pathologic, molecular genetic features. Session IV of the 2020 EAHP Workshop covered aggressive, predominantly high-grade B-cell lymphomas, many that were difficult to classify. In this manuscript, we summarize the features of the submitted cases and highlight differential diagnostic difficulties. We specifically review issues related to high-grade B-cell lymphomas (HGBCLs) with MYC and BCL2 and/or BCL6 rearrangements including TdT expression in these cases, HGBCL, not otherwise specified, large B-cell lymphomas with IRF4 rearrangement, high-grade/large B-cell lymphomas with 11q aberration, Burkitt lymphoma, and pleomorphic mantle cell lymphoma. Since the workshop, the 5th edition of the WHO Classification for Haematolymphoid Tumours (WHO-HAEM5) and International Consensus Classification (ICC) 2022 were published. We endeavor to use the updated terminology.

Prognostic significance of copy number gains of MYC detected by fluorescence in situ hybridization in large B-cell lymphoma

The MYC protooncogene plays a critical role in many cellular processes. MYC translocations are recurrent in large B-cell lymphomas (LBCLs) where they exhibit a negative effect on survival. Gain of MYC copies is also frequently identified; however, there is no consensus on the frequency and prognostic significance of MYC copy gains. We collected FISH data for MYC with reflex testing for BCL2 and BCL6 and IHC results at diagnosis for a cohort of 396 de novo and transformed LBCL cases and compared progression-free (PFS) and overall survival (OS) to determine the prognostic impact of extra MYC copies. The prevalence of cases with MYC copy number gain was 20.9%. PFS was shorter for patients with ≥5 MYC copies compared to controls (p = 0.0005, HR = 2.25). .MYC gain trended towards worse OS; patients with ≥7MYC copies had worse OS (p = 0.013), similar to patients with MYC translocations. We propose that MYC gain represents a dose-dependent prognostic factor for LBCLs.

Diffuse Large B-Cell Lymphoma, Not Otherwise Specified (DLBCL NOS) Presenting as Multiple Subcutaneous Nodules: An Unusual Cutaneous Presentation of Systemic Disease

Diffuse large B-cell lymphoma, not otherwise specified (DLBCL NOS) is the most common lymphoid malignancy in the Western world and classically presents as a rapidly enlarging nodal or extranodal mass. Cutaneous involvement by systemic DLBCL NOS is an infrequent clinical presentation, encountered in only 1.5-3.5% of cases, while disseminated cutaneous disease with multiple subcutaneous nodules at the time of diagnosis is unusual and can present a diagnostic challenge. The differential diagnosis when encountering a high-grade B-cell malignancy at a cutaneous site is broad and includes primary cutaneous follicle center lymphoma (PCFCL), primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT), high-grade B-cell lymphoma with MYC and BCL2 rearrangements (HGBCL-MYC/BCL2), and other potential entities which must all be carefully considered before rendering a final diagnosis. In this report, we describe the case of a 69-year-old man who was seen at our hospital due to generalized weakness and was found to have multiple subcutaneous nodules representing disseminated DLBCL NOS. The case was complicated by concurrent monoclonal B-cell lymphocytosis involving the bone marrow.

Cytogenetics in the management of mature B-cell non-Hodgkin lymphomas: Guidelines from the Groupe Francophone de Cytogénétique Hematologique (GFCH)

Non-Hodgkin lymphomas (NHL) consist of a wide range of clinically, phenotypically and genetically distinct neoplasms. The accurate diagnosis of mature B-cell non-Hodgkin lymphoma relies on a multidisciplinary approach that integrates morphological, phenotypical and genetic characteristics together with clinical features. Cytogenetic analyses remain an essential part of the diagnostic workup for mature B-cell lymphomas. Karyotyping is particularly useful to identify hallmark translocations, typical cytogenetic signatures as well as complex karyotypes, all bringing valuable diagnostic and/or prognostic information. Besides the well-known recurrent chromosomal abnormalities such as, for example, t(14;18)(q32;q21)/IGH::BCL2 in follicular lymphoma, recent evidences support a prognostic significance of complex karyotype in mantle cell lymphoma and Waldenström macroglobulinemia. Fluorescence In Situ Hybridization is also a key analysis playing a central role in disease identification, especially in genetically-defined entities, but also in predicting transformation risk or prognostication. This can be exemplified by the pivotal role of MYC, BCL2 and/or BCL6 rearrangements in the diagnostic of aggressive or large B-cell lymphomas. This work relies on the World Health Organization and the International Consensus Classification of hematolymphoid tumors together with the recent cytogenetic advances. Here, we review the various chromosomal abnormalities that delineate well-established mature B-cell non-Hodgkin lymphoma entities as well as newly recognized genetic subtypes and provide cytogenetic guidelines for the diagnostic management of mature B-cell lymphomas.

Induction treatment in high-grade B-cell lymphoma with a concurrent MYC and BCL2 and/or BCL6 rearrangement: a systematic review and meta-analysis

Background and aim

High-grade B cell lymphomas with concomitant MYC and BCL2 and/or BCL6 rearrangements (HGBCL-DH/TH) have a poor prognosis when treated with the standard R-CHOP-like chemoimmunotherapy protocol. Whether this can be improved using intensified regimens is still under debate. However, due to the rarity of HGBCL-DH/TH there are no prospective, randomized controlled trials (RCT) available. Thus, with this systematic review and meta-analysis we attempted to compare survival in HGBCL-DH/TH patients receiving intensified vs. R-CHOP(-like) regimens.

Methods

The PubMed and Web of Science databases were searched for original studies reporting on first-line treatment in HGBCL-DH/TH patients from 08/2014 until 04/2022. Studies with only localized stage disease, ≤10 patients, single-arm, non-full peer-reviewed publications, and preclinical studies were excluded. The quality of literature and the risk of bias was assessed using the Methodological Index for Non-Randomized Studies (MINORS) and National Heart, Lung, and Blood Institute (NHLBI) Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Random-effect models were used to compare R-CHOP-(like) and intensified regimens regarding 2-year overall survival (2y-OS) and 2-year progression-free survival (2y-PFS).

Results

Altogether, 11 retrospective studies, but no RCT, with 891 patients were included. Only four studies were of good quality based on aforementioned criteria. Intensified treatment could improve 2y-OS (hazard ratio [HR]=0.78 [95% confidence interval [CI] 0.63-0.96]; p=0.02) as well as 2y-PFS (HR=0.66 [95% CI 0.44-0.99]; p=0.045).

Conclusions

This meta-analysis indicates that intensified regimens could possibly improve 2y-OS and 2y-PFS in HGBCL-DH/TH patients. However, the significance of these results is mainly limited by data quality, data robustness, and its retrospective nature. There is still a need for innovative controlled clinical trials in this difficult to treat patient population.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42022313234.

A non-randomized risk-adjusted comparison of lenalidomide + R-CHOP versus R-CHOP for MYC-rearranged DLBCL patients

Patients with MYC rearranged (MYC-R) diffuse large B-cell lymphoma (DLBCL) have a poor prognosis. Previously, we demonstrated in a single-arm phase II trial (HOVON-130) that addition of lenalidomide to R-CHOP (R2CHOP) is well-tolerated and yields similar complete metabolic remission rates as more intensive chemotherapy regimens in literature. In parallel with this single-arm interventional trial, a prospective observational screening cohort (HOVON-900) was open in which we identified all newly diagnosed MYC-R DLBCL patients in the Netherlands. Eligible patients from the observational cohort that were not included in the interventional trial served as control group in the present risk-adjusted comparison. R2CHOP treated patients from the interventional trial (n = 77) were younger than patients in the R-CHOP control cohort (n = 56) (median age 63 versus 70 years, p = 0.018) and they were more likely to have a lower WHO performance score (p = 0.013). We adjusted for differences at baseline using 1:1 matching, multivariable analysis, and weighting using the propensity score to reduce treatment-selection bias. These analyses consistently showed improved outcome after R2CHOP with HRs of 0.53, 0.51, and 0.59, respectively, for OS, and 0.53, 0.59, and 0.60 for PFS. Thus, this non-randomized risk-adjusted comparison supports R2CHOP as an additional treatment option for MYC-R DLBCL patients.

Progression of follicular lymphoma and related entities: Report from the 2021 SH/EAHP Workshop

OBJECTIVES

The 2021 Society for Hematopathology and European Association for Haematopathology Workshop addressed the molecular and cytogenetic underpinnings of transformation and transdifferentiation in lymphoid neoplasms.

METHODS

Session 4, "Transformations of Follicular Lymphoma," and session 5, "Transformations of Other B-Cell Lymphomas," included 45 cases. Gene alteration analysis and expression profiling were performed on cases with submitted formalin-fixed, paraffin embedded tissue.

RESULTS

The findings from session 4 suggest that "diffuse large B-cell lymphoma/high-grade B-cell lymphoma with rearrangements of MYC and BCL2" is a distinct category arising from the constraints of a preexisting BCL2 translocation. TdT expression in aggressive B-cell lymphomas is associated with MYC rearrangements, immunophenotypic immaturity, and a dismal prognosis but must be differentiated from lymphoblastic -lymphoma. Cases in session 5 illustrated unusual morphologic and immunophenotypic patterns of transformation. Additionally, the findings support the role of cytogenetic abnormalities-specifically, MYC and NOTCH1 rearrangements-as well as single gene alterations, including TP53, in transformation.

CONCLUSIONS

Together, these unique cases and their accompanying molecular and cytogenetic data suggest potential mechanisms for and unusual patterns of transformation in B-cell lymphomas and indicate numerous opportunities for further study.

Large B-Cell Lymphomas in the 5th Edition of the WHO-Classification of Haematolymphoid Neoplasms-Updated Classification and New Concepts

The family/class of the large B-cell lymphomas (LBCL) in the 5th edition of the World Health Organization (WHO) classification of haematolymphoid tumors (WHO-HAEM5) features only a few major changes as compared to the 4th edition. In most entities, there are only subtle changes, many of them only representing some minor modifications in diagnostic terms. Major changes have been made in the diffuse large B-cell lymphomas (DLBCL)/high-grade B-cell lymphomas (HGBL) associated with MYC and BCL2 and/or BCL6 rearrangements. This category now consists of MYC and BCL2 rearranged cases exclusively, while the MYC/BCL6 double hit lymphomas now constitute genetic subtypes of DLBCL, not otherwise specified (NOS) or of HGBL, NOS. Other major changes are the conceptual merger of lymphomas arising in immune-privileged sites and the description of LBCL arising in the setting of immune dysregulation/deficiency. In addition, novel findings concerning underlying biological mechanisms in the pathogenesis of the different entities are provided.

The Obesity Controversy: Does It Impact Treatment Response in Diffuse Large B-Cell Lymphoma?

Background: We aimed to investigate the association of body mass index (BMI) with treatment response in patients with DLBCL. Material and Methods: Seventy-nine DLBCL subjects were included in this study. Data about patient age, sex, serum LDH level, presence of B symptoms, IPI score, ECOG performance score, disease stage, extranodal involvement, and BMI values at diagnosis were retrieved by retrospective patient record review. Patients were staged according to Ann Arbor classification using CT and/or PET/CT findings, and the presence of B symptoms. Body mass index was calculated by dividing weight in kilograms by height in meters squared (kg/m2). Patients were divided into groups according to their BMI as underweight (BMI≤ 18.5 kg/m2), normal weight (BMI 18.5-25 kg/m2), overweight (BMI 25-30 kg/m2), and obese (BMI≥ 30 kg/m2), as defined by the World Health Organization. Results: Patients were divided into four groups according to their BMIs, but because there was only one patient in the underweight group, comparisons were performed between normal-weight, overweight, and obese patients. There was no statistically significant difference between these groups in terms of age, sex, serum LDH level, disease stage, presence of B symptoms, extranodal involvement, ECOG performance score, IPI score and treatment response (p= 0.070, 0.704, 0.325, 0.464, 0.254, 0.152, 0.658, 0.620, and 0.947, respectively). Conclusion: In our study, we showed that BMI has no significant impact on treatment response in patients with DLBCL.

Synergistic disruption of BTK and BCL-2 causes apoptosis while inducing ferroptosis in double-hit lymphoma

Double-hit lymphoma (DHL) is an aggressive subset of Diffuse Large B-cell Lymphoma (DLBCL) with poor outcomes and without satisfying treatment options. BTK inhibitor monotherapy is ineffective to suppress aggressive lymphoma. Hence, combination with other potential agents is warranted. Here, we demonstrated the second generation of BTK inhibitor, zanubrutinib, and a BCL-2 inhibitor, navitoclax, worked in synergistic manner to suppress DHL. Comprehensive in silico approach by interrogating single-cell to bulk-level profiling was employed along with in vitro and in vivo validation in DHL cell lines. Ablation of BTK enhanced sensitivity to navitoclax and suppressed proliferation of DHL cells. Combination of second generation of BTK inhibitor with navitoclax synergistically suppressed DLBCL cells with higher synergy score in DHL subset. The drug combination triggered apoptosis and ferroptosis, with the latter being characterized by reactive oxygen species (ROS) accumulation, extensive lipid peroxidation, and depletion of reduced glutathione. Moreover, ablation of BTK sensitized DHL cells to ferroptosis. Mechanistically, disruption of BTK and BCL-2 triggered ferroptosis by downregulating NRF2 and HMOX1, while deactivating GPX4. Combination of zanubrutinib and navitoclax effectively suppressed tumor growth in vivo. Our data suggest that zanubrutinib and navitoclax synergistically suppressed DHL by inducing apoptosis and ferroptosis.

High-grade B-cell lymphoma (HGBL)-NOS is clinicopathologically and genetically more similar to DLBCL/HGBL-DH than DLBCL

High-grade B-cell lymphoma, not otherwise specified (HGBL-NOS) is rare and data focused on these neoplasms is lacking. We studied the clinicopathologic and genetic features of 136 HGBL-NOS patients and compared them to patients with DLBCL/HGBL-DH (n = 224, defined by 5th Edition WHO) and DLBCL (n = 217). HGBL-NOS patients had clinical features similar to DLBCL/HGBL-DH patients. MYC rearrangement (MYC-R) was present in 43% of HGBL-NOS. With induction regimen similar to DLBCL/HGBL-DH patients, HGBL-NOS patients had a median overall survival (OS) of 28.9 months, similar to DLBCL/HGBL-DH (p = 0.48) but inferior to DLBCL patients (p = 0.03). R-EPOCH induction was associated with improved OS compared with R-CHOP. MYC-R, history of lymphoma, and high IPI were independent adverse prognostic factors in HGBL-NOS patients. Whole transcriptome profiling performed on a subset of HGBL-NOS cases showed a profile more similar to DLBCL/HGBL-DH than to DLBCL; 53% of HGBL-NOS had a DH-like signature (DH-like-Sig) and were enriched for MYC-R. DH-like-Sig+ HGBL-NOS patients had a poorer OS than DH-like-Sig-negative patients (p = 0.04). In conclusion, HGBL-NOS has clinicopathologic features and a gene expression profile more similar to DLBCL/HGBL-DH than to DLBCL. Cases of HGBL-NOS frequently carry MYC-R and have a DH-like-Sig+. R-EPOCH induction in HGBL-NOS appears associated with improved OS compared with standard R-CHOP.

Burkitt lymphoma

Burkitt lymphoma (BL) is an aggressive form of B cell lymphoma that can affect children and adults. The study of BL led to the identification of the first recurrent chromosomal aberration in lymphoma, t(8;14)(q24;q32), and subsequent discovery of the central role of MYC and Epstein-Barr virus (EBV) in tumorigenesis. Most patients with BL are cured with chemotherapy but those with relapsed or refractory disease usually die of lymphoma. Historically, endemic BL, non-endemic sporadic BL and the immunodeficiency-associated BL have been recognized, but differentiation of these epidemiological variants is confounded by the frequency of EBV positivity. Subtyping into EBV⁺ and EBV^- BL might better describe the biological heterogeneity of the disease. Phenotypically resembling germinal centre B cells, all types of BL are characterized by dysregulation of MYC due to enhancer activation via juxtaposition with one of the three immunoglobulin loci. Additional molecular changes commonly affect B cell receptor and sphingosine-1-phosphate signalling, proliferation, survival and SWI-SNF chromatin remodelling. BL is diagnosed on the basis of morphology and high expression of MYC. BL can be effectively treated in children and adolescents with short durations of high dose-intensity multiagent chemotherapy regimens. Adults are more susceptible to toxic effects but are effectively treated with chemotherapy, including modified versions of paediatric regimens. The outcomes in patients with BL are good in high-income countries with low mortality and few late effects, but in low-income and middle-income countries, BL is diagnosed late and is usually treated with less-effective regimens affecting the overall good outcomes in patients with this lymphoma.

B-cell Lymphoma 6 (BCL6): From Master Regulator of Humoral Immunity to Oncogenic Driver in Pediatric Cancers

B-cell lymphoma 6 (BCL6) is a protooncogene in adult and pediatric cancers, first identified in diffuse large B-cell lymphoma (DLBCL) where it acts as a repressor of the tumor suppressor TP53, conferring survival, protection, and maintenance of lymphoma cells. BCL6 expression in normal B cells is fundamental in the regulation of humoral immunity, via initiation and maintenance of the germinal centers (GC). Its role in B cells during the production of high affinity immunoglobins (that recognize and bind specific antigens) is believed to underpin its function as an oncogene. BCL6 is known to drive the self-renewal capacity of leukemia-initiating cells (LIC), with high BCL6 expression in acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and glioblastoma (GBM) associated with disease progression and treatment resistance. The mechanisms underpinning BCL6-driven therapy resistance are yet to be uncovered; however, high activity is considered to confer poor prognosis in the clinical setting. BCL6's key binding partner, BCL6 corepressor (BCOR), is frequently mutated in pediatric cancers and appears to act in concert with BCL6. Using publicly available data, here we show that BCL6 is ubiquitously overexpressed in pediatric brain tumors, inversely to BCOR, highlighting the potential for targeting BCL6 in these often lethal and untreatable cancers. In this review, we summarize what is known of BCL6 (role, effect, mechanisms) in pediatric cancers, highlighting the two sides of BCL6 function, humoral immunity, and tumorigenesis, as well as to review BCL6 inhibitors and highlight areas of opportunity to improve the outcomes of patients with pediatric cancer.

Copy Number Alteration and Mutational Profile of High-Grade B-Cell Lymphoma with MYC and BCL2 and/or BCL6 Rearrangements, Diffuse Large B-Cell Lymphoma with MYC-Rearrangement, and Diffuse Large B-Cell Lymphoma with MYC-Cluster Amplification

Diffuse large B-cell lymphoma (DLBCL) with MYC alteration is classified as high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements (double/triple-hit lymphoma; DHL/THL), DLBCL with MYC rearrangement (single-hit lymphoma; SHL) and DLBCL with MYC-cluster amplification (MCAD). To elucidate the genetic features of DHL/THL, SHL, and MCAD, 23 lymphoma cases from Tokai University Hospital were analyzed. The series included 10 cases of DHL/THL, 10 cases of SHL and 3 cases of MCAD. The analysis used whole-genome copy number microarray analysis (OncoScan) and a custom-made next-generation sequencing (NGS) panel of 115 genes associated with aggressive B-cell lymphomas. The copy number alteration (CNA) profiles were similar between DHL/THL and SHL. MCAD had fewer CNAs than those of DHL/THL and SHL, except for +8q24. The NGS profile characterized DHL/THL with a higher "mutation burden" than SHL (17 vs. 10, p = 0.010), and the most relevant genes for DHL/THL were BCL2 and SOCS1, and for SHL was DTX1. MCAD was characterized by mutations of DDX3X, TCF3, HLA-A, and TP53, whereas MYC was unmutated. In conclusion, DHL/THL, SHL, and MCAD have different profiles.

Baseline radiomics features and MYC rearrangement status predict progression in aggressive B-cell lymphoma

We investigated whether the outcome prediction of patients with aggressive B-cell lymphoma can be improved by combining clinical, molecular genotype, and radiomics features. MYC, BCL2, and BCL6 rearrangements were assessed using fluorescence in situ hybridization. Seventeen radiomics features were extracted from the baseline positron emission tomography-computed tomography of 323 patients, which included maximum standardized uptake value (SUVmax), SUVpeak, SUVmean, metabolic tumor volume (MTV), total lesion glycolysis, and 12 dissemination features pertaining to distance, differences in uptake and volume between lesions, respectively. Logistic regression with backward feature selection was used to predict progression after 2 years. The predictive value of (1) International Prognostic Index (IPI); (2) IPI plus MYC; (3) IPI, MYC, and MTV; (4) radiomics; and (5) MYC plus radiomics models were tested using the cross-validated area under the curve (CV-AUC) and positive predictive values (PPVs). IPI yielded a CV-AUC of 0.65 ± 0.07 with a PPV of 29.6%. The IPI plus MYC model yielded a CV-AUC of 0.68 ± 0.08. IPI, MYC, and MTV yielded a CV-AUC of 0.74 ± 0.08. The highest model performance of the radiomics model was observed for MTV combined with the maximum distance between the largest lesion and another lesion, the maximum difference in SUVpeak between 2 lesions, and the sum of distances between all lesions, yielding an improved CV-AUC of 0.77 ± 0.07. The same radiomics features were retained when adding MYC (CV-AUC, 0.77 ± 0.07). PPV was highest for the MYC plus radiomics model (50.0%) and increased by 20% compared with the IPI (29.6%). Adding radiomics features improved model performance and PPV and can, therefore, aid in identifying poor prognosis patients.

Targeting the MYC interaction network in B-cell lymphoma via histone deacetylase 6 inhibition

Overexpression of MYC is a genuine cancer driver in lymphomas and related to poor prognosis. However, therapeutic targeting of the transcription factor MYC remains challenging. Here, we show that inhibition of the histone deacetylase 6 (HDAC6) using the HDAC6 inhibitor Marbostat-100 (M-100) reduces oncogenic MYC levels and prevents lymphomagenesis in a mouse model of MYC-induced aggressive B-cell lymphoma. M-100 specifically alters protein-protein interactions by switching the acetylation state of HDAC6 substrates, such as tubulin. Tubulin facilitates nuclear import of MYC, and MYC-dependent B-cell lymphoma cells rely on continuous import of MYC due to its high turn-over. Acetylation of tubulin impairs this mechanism and enables proteasomal degradation of MYC. M-100 targets almost exclusively B-cell lymphoma cells with high levels of MYC whereas non-tumor cells are not affected. M-100 induces massive apoptosis in human and murine MYC-overexpressing B-cell lymphoma cells. We identified the heat-shock protein DNAJA3 as an interactor of tubulin in an acetylation-dependent manner and overexpression of DNAJA3 resulted in a pronounced degradation of MYC. We propose a mechanism by which DNAJA3 associates with hyperacetylated tubulin in the cytoplasm to control MYC turnover. Taken together, our data demonstrate a beneficial role of HDAC6 inhibition in MYC-dependent B-cell lymphoma.

Altered pathways and targeted therapy in double hit lymphoma

High-grade B-cell lymphoma with translocations involving MYC and BCL2 or BCL6, usually referred to as double hit lymphoma (DHL), is an aggressive hematological malignance with distinct genetic features and poor clinical prognosis. Current standard chemoimmunotherapy fails to confer satisfying outcomes and few targeted therapeutics are available for the treatment against DHL. Recently, the delineating of the genetic landscape in tumors has provided insight into both biology and targeted therapies. Therefore, it is essential to understand the altered signaling pathways of DHL to develop treatment strategies with better clinical benefits. Herein, we summarized the genetic alterations in the two DHL subtypes (DHL-BCL2 and DHL-BCL6). We further elucidate their implications on cellular processes, including anti-apoptosis, epigenetic regulations, B-cell receptor signaling, and immune escape. Ongoing and potential therapeutic strategies and targeted drugs steered by these alterations were reviewed accordingly. Based on these findings, we also discuss the therapeutic vulnerabilities that coincide with these genetic changes. We believe that the understanding of the DHL studies will provide insight into this disease and capacitate the finding of more effective treatment strategies.

Exploring Current Challenges and Perspectives for Automatic Reconstruction of Clonal Evolution

BACKGROUND/AIM

In the field of cancer research, reconstructing clonal evolution is of major interest. The technique provides new insights for analysis and prediction of tumor development. However, reconstruction based on mutational data is characterized by several challenges.

MATERIALS AND METHODS

By performing extensive literature research, we identified 51 currently available tools for reconstructing clonal evolution. By analyzing two cancer data sets (n=21), we investigated the applicability and performance of each tool.

RESULTS

Seventeen out of 51 tools could be applied to our data. Correct clustering of variants can be observed for 4 patients in the presence of ≤3 clusters and ≥5 time points. Correct phylogenetic trees are determined for 10 patients. Accurate visualization is possible, by applying adjustments to the original algorithms.

CONCLUSION

Despite bearing considerable potential, automatic reconstruction of clonal evolution remains challenging. To replace tedious manual reconstruction, further research including systematic error analyses using simulation tools needs to be conducted.

Dysregulated Expression of Long Non-Coding RNA MINCR and EZH2 in Colorectal Cancer

BACKGROUND

As critical regulators, lncRNAs have attracted attention from researchers for diagnostic, prognostic, and therapeutic purposes in human carcinogenesis via interfering with mRNAs such as EZH2. Nevertheless, the potent roles and molecular mechanisms of these RNAs in CRC are not clearly known.

METHODS

In this study, the tissue expressions of lncRNA MINCR and EZH2 mRNA between colorectal tumors and polyps were compared with the adjacent normal tissues collected from 114 Iranian patients, using real-time PCR method. Furthermore, the correlation of the expression levels of MINCR and EZH2 with other clinical parameters was evaluated.

RESULTS

The significant overexpression of MINCR and EZH2 were observed in the CRC tissues compared to control tissues (p < 0.0001). This observation confirmed the association of these expression enhancements with the pathological stage of CRC patients.

CONCLUSION

Our findings revealed that the expression of MINCR significantly alters during CRC development, and it can be identified as a potential biomarker for the detection of CRC.

AID is a poor prognostic marker of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements

Diffuse large B-cell lymphoma with MYC rearrangement is defined as double/triple-hit lymphoma (DHL/THL) or single-hit lymphoma (SHL) by the inclusion of the BCL2 and BCL6 rearrangements status. DHL/THL is called as "high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements" in the World Health Organization 2017 Classification of Tumors of Hematopoietic and Lymphoid Tissues. To find a prognostic biomarker of DHL/THL, we firstly examined 19 cases (molecular analysis series;10 cases of DHL/THL and 9 cases of SHL) with gene expression profile analysis. The gene expression profile analysis showed that the high expression of AICDA was associated with an adverse prognosis in DHL/THL, but not in SHL. Then, we evaluated immunohistochemical expression of AID, the protein product of AICDA, in 50 cases (molecular analysis series of 19 cases and additional immunohistochemistry series of 31 cases; 12 cases of DHL/THL and 19 cases of SHL) and confirmed that its expression was also associated with an adverse prognosis in DHL/THL. Therefore, AICDA and AID can be a predictor of an adverse clinical outcome in DHL/THL and immunohistochemistry of AID is useful to find DHL/THL-adverse prognosis group.

EBV-positive high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements: a multi-institutional study

AIMS

It is unknown whether Epstein-Barr virus (EBV) infection can occur in high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements, also known as double-hit or triple-hit lymphoma (DHL/THL).

METHODS AND RESULTS

Here we report 16 cases of EBV+ DHL/THL from screening 846 cases of DHL/THL and obtaining additional EBV+ cases through multi-institutional collaboration: 8 MYC/BCL2 DHL, 6 MYC/BCL6 DHL, and 2 THL. There were 8 men and 8 women with a median age of 65 years (range, 32-86). Two patients had a history of follicular lymphoma and one had AIDS. Nine of 14 patients had an International Prognostic Index of ≥3. Half of the cases showed high-grade/Burkitt-like morphology and the other half diffuse large B-cell lymphoma morphology. By immunohistochemistry, the lymphoma cells were positive for MYC (n=14/16), BCL2 (n=12/16), BCL6 (n=14/16), CD10 (n=13/16), and MUM1 (n=6/14). By Hans algorithm, 13 cases were classified as GCB and 3 as non-GCB. The lymphomas frequently showed an EBV latency type I with a median EBV-encoded small RNAs of 80% positive cells (range, 20-100%). After a median follow-up of 36.3 months (range, 2.0-41.6), 7 patients died with a median survival of 15.4 months (range, 3.4-47.3) after diagnosis of EBV+ DHL/THL. Five of 6 patients with MYC/BCL6 DHL were alive including 4 in complete remission. In contrast, only 4/10 patients with MYC/BCL2 DHL or THL were alive including 2 in complete remission. The median survival in patients with MYC/BCL6 DHL was unreached and was 21.6 months in patients with MYC/BCL2 DHL or THL.

CONCLUSIONS

EBV infection in DHL/THL is rare (~1.5%). Cases of EBV+ DHL/THL are largely similar to their EBV-negative counterparts clinicopathologically. Our findings expand the spectrum of EBV+ B-cell lymphomas currently recognized in the WHO classification and suggest differences between EBV+ MYC/BCL2 and MYC/BCL6 DHL that may have therapeutic implications.

BCL2 translocation in high grade B cell lymphoma (NOS, DH/TH) is associated with reduced progression free survival

High Grade B Cell Lymphoma, NOS, and High Grade B Cell Lymphoma with Dual Hit or Triple Hit have been recently recategorized in the 2016 revision of the WHO classification of lymphoid neoplasms. In this study we have characterized the genetic, histopathological, and clinical features of a series of this type of lymphoid neoplasia (17 HGBCL NOS and 53 HGBCL DH/TH).HGBCL NOS showed better response to first line treatment than HGBCL with DH/TH but no significant differences in PFS or OS were found between the two categories. Survival analysis in the whole cohort of cases found that only the presence of BCL2 translocation was significantly associated with PFS. Other clinical features such as IPI, LDH or stage were equivalent in both categories. Furthermore, both high grade and DLBCL morphological patterns showed equivalent PFS and OS in this set of High grade BCL NOS/DH/TH.Key pointsBCL2 translocation in High Grade B Cell Lymphoma NOS and High Grade B Cell Lymphoma with DH/TH is associated with reduced progression free survival.Both high grade and DLBCL morphological patterns showed equivalent outcome regarding PFS and OS in HGBCL.

Molecular Update and Evolving Classification of Large B-Cell Lymphoma

Diffuse large B-cell lymphomas (DLBCLs) are aggressive B-cell neoplasms with considerable clinical, biologic, and pathologic diversity. The application of high throughput technologies to the study of lymphomas has yielded abundant molecular data leading to the identification of distinct molecular identities and novel pathogenetic pathways. In light of this new information, newly refined diagnostic criteria have been established in the fourth edition of the World Health Organization (WHO) consensus classification of lymphomas, which was revised in 2016. This article reviews the histopathological and molecular features of the various aggressive B-cell lymphoma subtypes included in the updated classification.

Fluorescent nanoparticle-mediated semiquantitative MYC protein expression analysis in morphologically diffuse large B-cell lymphoma

The current World Health Organization (WHO) classification defines a new disease entity of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements, making fluorescence in situ hybridization (FISH) screening for these genes mandatory. In addition, the prognostic significance of MYC expression was reported, with a cut-off value of 40%. However, interobserver discrepancies arise due to the heterogeneous intensity of MYC expression by immunohistochemistry. Moreover, a cut-off value of positivity for MYC protein in diffuse large B-cell lymphoma (DLBCL) varies among studies at present. Here, we applied a high-sensitivity semiquantitative immunohistochemical technique using fluorescent nanoparticles called phosphor-integrated dots (PID) to evaluate the MYC expression in 50 de novo DLBCL cases, and compared it with the conventional diaminobenzidine (DAB)-developing system. The high MYC expression detected by the PID-mediated system predicted poor overall survival in DLBCL patients. However, we found no prognostic value of MYC protein expression for any cut-off value by the DAB-developing system, even if the intensity was considered. These results indicate that the precise evaluation of MYC protein expression can clarify the prognostic values in DLBCL, irrespective of MYC rearrangement.

Molecular characterization of Burkitt lymphoma in the breast or ovary

Breast and ovary have been described as rare but typical sites of presentation of Burkitt lymphoma (BL) in females, particularly after puberty. We revised a historic series of 44 lymphomas of the breast or the ovary in women diagnosed between 1973 and 2014 as BL. Fluorescence in situ hybridization (FISH) was applied to all, and array-based copy number analysis as well as expression profiling to a subset of those cases. Of the 42 cases evaluable for FISH, 19 cases showed an IG-MYC translocation but only 9 of those fulfilled the criteria of the current WHO classification for the diagnosis of BL. Those nine cases resembled BL of other sites with regard to molecular features. Our findings along with literature data suggest that breast and ovarian BL (1) seem to be rarer than hitherto assumed, (2) share typical molecular features with other BL, and (3) predominantly affect women in the fertile age.

Diffuse Large B-Cell Lymphoma: Recognition of Markers for Targeted Therapy

Diffuse large B-cell lymphomas (DLBCL)s, the most common type of Non-Hodgkin’s Lymphoma, constitute a heterogeneous group of disorders including different disease sites, strikingly diverse molecular features and a profound variability in the clinical behavior. Molecular studies and clinical trials have partially revealed the underlying causes for this variability and have made possible the recognition of some molecular variants susceptible of specific therapeutic approaches. The main histogenetic groups include the germinal center, activated B cells, thymic B cells and terminally differentiated B cells, a basic scheme where the large majority of DLBCL cases can be ascribed. The nodal/extranodal origin, specific mutational changes and microenvironment peculiarities provide additional layers of complexity. Here, we summarize the status of the knowledge and make some specific proposals for addressing the future development of targeted therapy for DLBC cases.

The "Burkitt-like" immunophenotype and genotype is rarely encountered in diffuse large B cell lymphoma and high-grade B cell lymphoma, NOS

Burkitt lymphoma (BL) is a B cell lymphoma composed of monomorphic medium-sized blastic cells with basophilic cytoplasm and a high proliferation index. BL has a characteristic immunophenotype of CD10 and BCL6 positive and BCL2 negative and harbours MYC gene rearrangements (MYCR) in >90% of the cases. Owing to its highly aggressive nature, intensified chemotherapy regimens are usually administered, requiring an exact diagnosis. Since the diagnosis usually warrants an integration of morphologic, immunophenotypic and genetic findings and because there is a morphologic overlap with the new WHO category of high-grade B cell lymphoma, not otherwise specified (HGBL, NOS) and some cases of diffuse large B cell lymphoma (DLBCL), we wanted to test the distinctiveness of the CD10+, BCL6+, BCL2- and MYCR positive immunopheno-genotype in a large cohort of >1000 DLBCL and HGBL. Only 9/982 DLBCL classified by an expert panel of haematopathologists (0.9%) displayed a single MYCR and were CD10+, BCL6+ and BCL2-. In a similar fashion, only one out of 32 HGBL, NOS (3%) displayed the "Burkitt-like" genetic/immunophenotypic constitution. The samples of non-BL showing the BL-typic immunopheno-genotype, interestingly, harboured higher copy number variations (CNV) by OncoScan analysis (mean 7.3 CNVs/sample; range: 2-13 vs. 2.4; range 0-6) and were also distinct from pleomorphic BL cases regarding their mutational spectrum by NGS analysis. This implies that the characteristic immunophenotype of BL, in concert with a single MYCR, is uncommon in these aggressive lymphomas, and that this constellation favours BL.

Mantle cell lymphomas with concomitant MYC and CCND1 breakpoints are recurrently TdT positive and frequently show high-grade pathological and genetic features

Chromosomal breakpoints involving the MYC gene locus, frequently referred to as MYC rearrangements (MYC - R+), are a diagnostic hallmark of Burkitt lymphoma and recurrent in many other subtypes of B-cell lymphomas including follicular lymphoma, diffuse large B-cell lymphoma and other high-grade B-cell lymphomas and are associated with an aggressive clinical course. In remarkable contrast, in MCL, only few MYC - R+ cases have yet been described. In the current study, we have retrospectively analysed 16 samples (MYC - R+, n = 15, MYC - R-, n = 1) from 13 patients and describe their morphological, immunophenotypic and (molecular) genetic features and clonal evolution patterns. Thirteen out of fifteen MYC - R+ samples showed a non-classical cytology including pleomorphic (centroblastic, immunoblastic), anaplastic or blastoid. MYC translocation partners were IG-loci in 4/11 and non-IG loci in 7/11 analysed cases. The involved IG-loci included IGH in 3 cases and IGL in one case. PAX5 was the non-IG partner in 2/7 patients. The MYC - R+ MCL reported herein frequently displayed characteristics associated with an aggressive clinical course including high genomic-complexity (6/7 samples), frequent deletions involving the CDKN2A locus (7/10 samples), high Ki-67 proliferation index (12/13 samples) and frequent P53 expression (13/13 samples). Of note, in 4/14 samples, SOX11 was not or only focally expressed and 3/13 samples showed focal or diffuse TdT-positivity presenting a diagnostic challenge as these features could point to a differential diagnosis of diffuse large B-cell lymphoma and/or lymphoblastic lymphoma/leukaemia.

High-grade B-Cell Lymphoma With MYC, BCL2, and/or BCL6 Translocations/Rearrangements: Clinicopathologic Features of 51 Cases in a Single Institution of South China

Double-hit/triple-hit lymphomas (DH/THLs) are high-grade B-cell lymphomas with MYC and BCL2 rearrangements and/or BCL6 rearrangements, which have poor outcomes after standard chemoimmunotherapy. This retrospective study analyzed 51 patients (range, 19 to 82 y) diagnosed from 2016 to 2019 and treated for DH/THL (n=34 MYC/BCL6 DHL, n=14 MYC/BCL2 DHL, n=3 THL) at one institution in South China. Extranodal lesions occurred in 32 patients (62.7%), more frequently in MYC/BCL6 DHL (22/34, 64.7%) than in MYC/BCL2 DHL (7/14, 50%). The most common extranodal sites were the stomach (8/32, 25.0%) and intestine (5/32, 15.6%). Most patients (33/45, 73.3%) presented with Ann Arbor stage III/IV. Interestingly, 14.3% (4/28) of MYC/BCL6 DHL tumors showed diffuse, medium-intensity CD30 expression. Epstein-Barr virus-encoded RNA was positive in 3 cases, all MYC/BCL6 DHL. Among 48 patients (94.1%) with follow-up data, 18 (37.5%) died owing to the disease, and the median survival was 5.5 months. Germinal center B cells were observed more frequently in MYC/BCL2 DHL (14/14, 100.0%) than in MYC/BCL6 DHL (15/34, 44.1%; P<0.001). Bone marrow involvement tended to lower overall survival (OS) (P=0.033). No association was observed between stage, B symptoms, lactate dehydrogenase levels, and central nervous system involvement and OS. A total of 25 patients (25/47, 53.2%) with previous hepatitis B virus (HBV) infections had significantly poorer OS (P=0.014). Chronic HBV infection was positively correlated with MYC/BCL6 DHL (r=0.317, P=0.030). Compared with DH/THL in western countries, the disease in South China has distinct characteristics with a higher prevalence of MYC/BCL6 DHL. We speculate that HBV is important in DH/THL tumorigenesis. These findings might provide clues for novel treatment strategies.

Treatment of patients with MYC rearrangement positive large B-cell lymphoma with R-CHOP plus lenalidomide: results of a multicenter HOVON phase II trial

Patients with MYC-rearrangement positive large B-cell lymphoma (MYC+ LBCL) have an inferior prognosis following standard first-line therapy with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) as compared to patients without MYC rearrangement. Although intensive chemotherapy regimens yield higher remission rates, toxicity remains a concern. Lenalidomide is an oral immunomodulatory drug which downregulates MYC and its target genes thereby providing support using lenalidomide as additional therapeutic option for MYC+ LBCL. A phase II trial was conducted evaluating the efficacy of lenalidomide (15 mg day 1-14) in combination with R-CHOP (R2CHOP) in newly diagnosed MYC+ LBCL patients identified through a nationwide MYC-FISH screening program. The primary endpoint was complete metabolic response (CMR) on centrally reviewed 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)-computer tomography (CT)-scan at end-of-treatment. Secondary endpoints were overall survival (OS), disease-free survival (DFS) and event-free survival (EFS). Eighty-two patients with stage II-IV MYC+ LBCL were treated with 6 cycles of R2CHOP. At EOT, 67% (confidence interval (CI) 58-75%) of the patients reached CMR. With a median follow-up of 25.4 months, 2-year estimates (95% CI) for OS, DFS, EFS were 73% (62-82%), 75% (63-84%) and 63% (52-73%) respectively. In this prospective trial for newly diagnosed MYC+ LBCL patients, we found that administering R2CHOP was safe, and yields comparable CMR and survival rates as in studies applying more intensive chemotherapy regimens. Hence, these findings offer new prospects for MYC+ LBCL patients and warrant comparison in prospective randomized clinical trials. This trial was registered at www.clinicaltrialsregister.eu (#2014-002654-39).

Evolving insights into the genomic complexity and immune landscape of diffuse large B-cell lymphoma: opportunities for novel biomarkers

Recently, comprehensive genomic analyses have allowed a better molecular characterization of diffuse large B-cell lymphoma (DLBCL), offering novel opportunities in patient risk stratification and management. In the era of precision medicine, this has allowed us to move closer toward a more promising therapeutic outcome in the setting of DLBCL. In this review, we highlight the newly reported heterogeneous mutational landscapes of DLBCL (from two whole-exome sequencing studies, and from a more recent work targeting a 293-gene of a hematologic malignancy-designed panel. Altogether, these studies provide further evidence of the clinical applicability of genomic tests. We also briefly review established biomarkers in DLBCL (e.g., MYC and TP53), and our understanding of the germinal center cell reaction, including its epigenetic regulation, emphasizing some of the key epigenetic modifiers that play a role in lymphomagenesis, with available therapeutic targets. In addition, we present current data regarding the role of immune landscapes in DLBCL (inflamed versus non-inflamed), how the recently defined molecular DLBCL subtypes may affect the cellular composition of the tumor microenvironment and the function of the immune cells, and how this new knowledge may result in promising therapeutic approaches in the near future.

[Fluorescence in situ hybridization in the diagnosis of aggressive B-cell lymphomas]

The introduction of new lymphoma entities that are defined by chromosomal rearrangements has led to changes concerning the diagnostic algorithms in routine hematopathology, particularly for the large group of aggressive B‑cell lymphomas. The new, genetically defined entity high-grade B‑cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements (double/triple hit lymphoma) is morphologically heterogenous and comprises lymphomas with the morphology of a diffuse large B‑cell lymphoma (DLBCL), but also cases with blastoid appearance as well as intermediate/Burkitt-like morphology. This implies a cytogenetic analysis for the final classification of aggressive lymphomas with DLBCL morphology, which constitute the most common lymphomas in daily practice. This analysis is currently most efficiently performed via a sequential fluorescence in situ hybridization (FISH) approach, with an initial MYC-FISH, that is followed (if required, i.e., if a MYC rearrangement is detected) by an analysis regarding a BCL2- and BCL6-chromosomal rearrangement. In addition, the update of the fourth edition of the WHO classification for hematopoietic neoplasms introduced additional lymphoma subgroups that are defined by chromosomal rearrangements, such as Burkitt-like lymphoma with 11q aberration as well as large B cell lymphoma with IRF4 rearrangement. Therefore, FISH currently plays an important role in the diagnostic armamentarium in routine diagnostic hematopathology.

Genetic evolution of in situ follicular neoplasia to aggressive B-cell lymphoma of germinal center subtype

In situ follicular neoplasia (ISFN) is the earliest morphologically identifiable precursor of follicular lymphoma (FL). Although it is genetically less complex than FL and has low risk for progression, ISFN already harbors secondary genetic alterations, in addition to the defining t(14;18)(q32;q21) translocation. FL, in turn, frequently progresses to diffuse large B-cell lymphoma (DLBCL) or high-grade B-cell lymphoma (HGBL). By BCL2 staining of available reactive lymphoid tissue obtained at any time point in patients with aggressive B-cell lymphoma (BCL), we identified ten paired cases of ISFN and DLBCL/HGBL, including six de novo tumors and four tumors transformed from FL as an intermediate step, and investigated their clonal evolution using microdissection and next-generation sequencing. A clonal relationship between ISFN and aggressive BCL was established by immunoglobulin and/or BCL2 rearrangements and/or the demonstration of shared somatic mutations for all ten cases. Targeted sequencing revealed CREBBP, KMT2D, EZH2, TNFRSF14 and BCL2 as the genes most frequently mutated already in ISFN. Based on the distribution of private and shared mutations, two patterns of clonal evolution were evident. In most cases, the aggressive lymphoma, ISFN and, when present, FL revealed divergent evolution from a common progenitor, whereas linear evolution with sequential accumulation of mutations was less frequent. In conclusion, we demonstrate for the first time that t(14;18)+ aggressive BCL can arise from ISFN without clinically evident FL as an intermediate step and that during this progression, branched evolution is common.

MYC's Fine Line Between B Cell Development and Malignancy

The transcription factor MYC is transiently expressed during B lymphocyte development, and its correct modulation is essential in defined developmental transitions. Although temporary downregulation of MYC is essential at specific points, basal levels of expression are maintained, and its protein levels are not completely silenced until the B cell becomes fully differentiated into a plasma cell or a memory B cell. MYC has been described as a proto-oncogene that is closely involved in many cancers, including leukemia and lymphoma. Aberrant expression of MYC protein in these hematological malignancies results in an uncontrolled rate of proliferation and, thereby, a blockade of the differentiation process. MYC is not activated by mutations in the coding sequence, and, as reviewed here, its overexpression in leukemia and lymphoma is mainly caused by gene amplification, chromosomal translocations, and aberrant regulation of its transcription. This review provides a thorough overview of the role of MYC in the developmental steps of B cells, and of how it performs its essential function in an oncogenic context, highlighting the importance of appropriate MYC regulation circuitry.

MYC in Germinal Center-derived lymphomas: Mechanisms and therapeutic opportunities

The rearrangement of immunoglobulin loci during the germinal center reaction is associated with an increased risk of chromosomal translocations that activate oncogenes such as MYC, BCL2 or BCL6, thus contributing to the development of B-cell lymphomas. MYC and BCL2 activation are initiating events in Burkitt's (BL) and Follicular Lymphoma (FL), respectively, but can occur at later stages in other subtypes such as Diffuse Large-B Cell Lymphoma (DLBCL). MYC can also be activated during the progression of FL to the transformed stage. Thus, either DLBCL or FL can give rise to aggressive double-hit lymphomas (DHL) with concurrent activation of MYC and BCL2. Research over the last three decades has improved our understanding of the functions of these oncogenes and the basis for their cooperative action in lymphomagenesis. MYC, in particular, is a transcription factor that contributes to cell activation, growth and proliferation, while concomitantly sensitizing cells to apoptosis, the latter being blocked by BCL2. Here, we review our current knowledge about the role of MYC in germinal center B-cells and lymphomas, discuss MYC-induced dependencies that can sensitize cancer cells to select pharmacological inhibitors, and illustrate their therapeutic potential in aggressive lymphomas-and in particular in DHL, in combination with BCL2 inhibitors.

Challenges and Opportunities for High-grade B-Cell Lymphoma With MYC and BCL2 and/or BCL6 Rearrangement (Double-hit Lymphoma)

The most common subtype of non-Hodgkin lymphoma, diffuse large B-cell lymphoma, is cured in approximately two thirds of patients after initial therapy. The remaining one-third of patients who suffer relapse or become refractory have very poor survival outcomes despite salvage chemotherapy with or without stem cell transplantation. A considerable proportion of relapsed or refractory large B cells belong to the WHO subtype known as high-grade B-cell lymphoma with rearrangement of MYC and BCL2 and/or BCL6, also known as double-hit lymphoma (DHL). Most DHL patients present with Ann Arbor's stage III/IV, a comparatively higher rate of extranodal involvement including bone marrow and central nervous system infiltration, high levels of lactate dehydrogenase, and an elevated Ki67 expression in the tumor cells. Newer therapeutic approaches, including targeted therapy against BCL2, MYC, or other associated pathways, are needed. In addition, recent therapies that harness the immune system, such as checkpoint inhibitors and chimeric antigen receptor T-cell therapy, are changing the paradigm of treatment for non-Hodgkin lymphoma and could impact the outcome of DHL.

Suppression of BCL6 function by HDAC inhibitor mediated acetylation and chromatin modification enhances BET inhibitor effects in B-cell lymphoma cells

Multiple genetic aberrations in the regulation of BCL6, including in acetyltransferase genes, occur in clinically aggressive B-cell lymphomas and lead to higher expression levels and activity of this transcriptional repressor. BCL6 is, therefore, an attractive target for therapy in aggressive lymphomas. In this study romidepsin, a potent histone deacetylase inhibitor (HDACi), induced apoptosis and cell cycle arrest in Burkitt and diffuse large B-cell lymphoma cell lines, which are model cells for studying the mechanism of action of BCL6. Romidepsin caused BCL6 acetylation at early timepoints inhibiting its function, while at later timepoints BCL6 expression was reduced and target gene expression increased due to chromatin modification. MYC contributes to poor prognosis in aggressive lymphoma. MYC function is reduced by inhibition of chromatin readers of the bromodomain and extra-terminal repeat (BET) family, which includes BRD4. The novel combination of romidepsin and JQ1, a BRD4 inhibitor was investigated and showed synergy. Collectively we suggest that the combination of HDACi and BRD4i should be pursued in further pre-clinical testing.

Prognostic analysis of CD5 expression in double-hit diffuse large B-cell lymphoma and effectiveness comparison in patients treated with dose-adjusted EPOCH plus rituximab/R-CHOP regimens

Objectives

To compare the efficacy of rituximab, dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide and doxorubicin (DA-EPOCH-R) with traditional rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) regimens in CD5+ double-hit lymphoma (DHL) and to evaluate prognostic factors.

Methods

We retrospectively studied 139 patients with newly diagnosed DHL/THL diffuse large B-cell lymphoma (including 20 cases CD5+ and 119 cases CD5−), 87 cases were MYC/BCL2 DHL, 30 cases were MYC/BCL6 DHL, 22 cases were THL. MYC, BCL2 and BCL6 rearrangements were examined by fluorescence in-situ hybridization. CD5 is detected by immunohistochemistry (IHC).

Results

The objective response rate (ORR) difference between CD5+ and CD5− was significant (80.0% vs 63.8%, P=0.003). The median follow-up time was 18 months (range: 4–39 months). Progression-free survival (PFS) of CD5+ group was significantly worse than that of CD5- (28.1% vs 59.0%, P=0.028), while no significant difference was observed in overall survival (OS) (32.1% vs 59.9%, P=0.057). Compared with the two regimens, the 2-year survival rate of DA-EPOCH-R group was significantly superior than that of R-CHOP (63.6% vs 45.4%, P=0.034 for PFS; 67.4% vs 47.8%, P=0.038 for OS). Besides, CD5+ patients receiving DA-EPOCH-R had survival benefits compared with R-CHOP in PFS (85.7% vs 23.0%, P=0.029), but there was no statistical difference in OS (87.7% vs 34.4.0%, P=0.064). However, in DA-EPOCH-R protocol, there was no significant difference between CD5+ DHL (MYC/BCl2 and MYC/BCL6) and triple-hit lymphoma (P=0.776 for PFS; P=0.728 for OS). Multivariate analysis showed that CD5+ treatment regimen and disease stage were independent prognostic factors.

Conclusion

Our retrospective study shows that CD5+ has a poorer prognosis than CD5− patients. Based on its improved lifetime and good tolerance on CD5+ patients, which is expected to become the first-line treatment for high-risk DLBCL types based on more clinical research.

Intraoral EBV-positive sporadic Burkitt lymphoma in an elderly patient with bilateral presentation

Sporadic Burkitt lymphoma (SBL) is a variant of Burkitt lymphoma that occurs worldwide, affecting mainly children and young adults. Association with Epstein-Barr virus (EBV) can be identified in approximately 20-30% of cases. Herein we described a case of a 63-year-old male presenting intraoral bilateral mandibular swelling, subjacent to fixed dental prosthesis, with one month of duration. Incisional biopsies were performed, and after two days, the patient was hospitalized due to malaise and breathing difficulty, and died after a week when an abdominal tumor was detected. The mandibular biopsies revealed a diffuse proliferation of medium-sized monomorphic atypical lymphoid cells exhibiting numerous mitoses and areas of "starry-sky" pattern. The tumor showed immunohistochemical positivity for CD20, CD10, Bcl-6, and Ki-67 (≈ 100%); it was negative for CD3, Bcl-2, Vs38c, and MUM-1. Positivity for EBV was found by in situ hybridization. The final diagnosis was intraoral SBL positive for EBV. Clinical, morphological and molecular criteria are necessary for the correct diagnosis of aggressive B-cell neoplasms positive for EBV in elderly patients.

Prognostic Significance of MYC Rearrangement and Translocation Partner in Diffuse Large B-Cell Lymphoma: A Study by the Lunenburg Lymphoma Biomarker Consortium

PURPOSE

MYC rearrangement (MYC-R) occurs in approximately 10% of diffuse large B-cell lymphomas (DLBCLs) and has been associated with poor prognosis in many studies. The impact of MYC-R on prognosis may be influenced by the MYC partner gene (immunoglobulin [IG] or a non-IG gene). We evaluated a large cohort of patients through the Lunenburg Lymphoma Biomarker Consortium to validate the prognostic significance of MYC-R (single-, double-, and triple-hit status) in DLBCL within the context of the MYC partner gene.

METHODS

The study cohort included patients with histologically confirmed DLBCL morphology derived from large prospective trials and patient registries in Europe and North America who were uniformly treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone therapy or the like. Fluorescence in situ hybridization for the MYC, BCL2, BCL6, and IG heavy and light chain loci was used, and results were correlated with clinical outcomes.

RESULTS

A total of 5,117 patients were identified of whom 2,383 (47%) had biopsy material available to assess for MYC-R. MYC-R was present in 264 (11%) of 2,383 patients and was associated with a significantly shorter progression-free and overall survival, with a strong time-dependent effect within the first 24 months after diagnosis. The adverse prognostic impact of MYC-R was only evident in patients with a concurrent rearrangement of BCL2 and/or BCL6 and an IG partner (hazard ratio, 2.4; 95% CI, 1.6 to 3.6; P < .001).

CONCLUSION

The negative prognostic impact of MYC-R in DLBCL is largely observed in patients with MYC double hit/triple-hit disease in which MYC is translocated to an IG partner, and this effect is restricted to the first 2 years after diagnosis. Our results suggest that diagnostic strategies should be adopted to identify this high-risk cohort, and risk-adjusted therapeutic approaches should be refined further.

High-resolution architecture and partner genes of MYC rearrangements in lymphoma with DLBCL morphology

Genomic rearrangements in the MYC locus occur in ∼12% of lymphomas with diffuse large B-cell lymphoma (DLBCL) morphology and are associated with inferior outcome. Previous studies exploring MYC rearrangements have primarily used fluorescence in situ hybridization (FISH) assays to characterize break-apart status but have rarely examined breakpoint location, and in some cases have not examined partner identity. We performed targeted sequencing of MYC, BCL2, BCL6, and the immunoglobulin (IG) loci in 112 tumors with DLBCL morphology harboring MYC rearrangement. We characterized the location of the MYC rearrangement at base pair resolution and identified the partner in 88 cases. We observed a cluster of breakpoints upstream of the MYC coding region and in intron 1 (the "genic cluster"). Genic cluster rearrangements were enriched for translocations involving IGH (80%), whereas nongenic rearrangements occurred mostly downstream of the MYC gene with a variety of partners, including IGL and IGK Other recurrent partners included BCL6, ZCCHC7, and RFTN1, which has not previously been described as a MYC partner. We compared 2 commercially available FISH break-apart assays for the MYC locus and observed discordant results in 32% of cases examined, including some with MYC-IGL and MYC-IGK rearrangements. In cases of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangement (HGBL-DH), so-called "double-hit" lymphomas, the majority of MYC rearrangements had non-IG partners (65%), with breakpoints outside the genic cluster (72%). In patients with de novo HGBL-DH of DLBCL morphology, MYC-IG rearrangements showed a trend toward inferior time to progression and overall survival compared with MYC-non-IG rearrangements. Our data reveal clinically relevant architecture of MYC rearrangements in lymphomas with DLBCL morphology.