The Impact of MYC Rearrangements and “Double Hit” Abnormalities in Diffuse Large B-Cell Lymphoma

Lessons from Using Genetically Engineered Mouse Models of MYC-Induced Lymphoma

Oncogenic overexpression of MYC leads to the fatal deregulation of signaling pathways, cellular metabolism, and cell growth. MYC rearrangements are found frequently among non-Hodgkin B-cell lymphomas enforcing MYC overexpression. Genetically engineered mouse models (GEMMs) were developed to understand MYC-induced B-cell lymphomagenesis. Here, we highlight the advantages of using Eµ-Myc transgenic mice. We thoroughly compiled the available literature to discuss common challenges when using such mouse models. Furthermore, we give an overview of pathways affected by MYC based on knowledge gained from the use of GEMMs. We identified top regulators of MYC-induced lymphomagenesis, including some candidates that are not pharmacologically targeted yet.

Primary gastric non-Hodgkin lymphomas: Recent advances regarding disease pathogenesis and treatment

Primary gastric lymphomas (PGLs) are distinct lymphoproliferative neoplasms described as heterogeneous entities clinically and molecularly. Their main histological types are diffuse large B-cell lymphoma (DLBCL) or mucosa-associated lymphoma tissue. PGL has been one of the main fields of clinical research of our group in recent years. Although gastric DLBCLs are frequent, sufficient data to guide optimal care are scarce. Until today, a multidisciplinary approach has been applied, including chemotherapy, surgery, radiotherapy or a combination of these treatments. In this minireview article, we provide an overview of the clinical manifestations, diagnosis and staging of these diseases, along with their molecular pathogenesis and the most important related clinical published series. We then discuss the scientific gaps, perils and pitfalls that exist regarding the aforementioned studies, in parallel with the unmet need for future research and comment on the proper methodology for such retrospective studies. Aiming to fill this gap, we retrospectively evaluated the trends in clinical presentation, management and outcome among 165 patients with DLBCL PGL who were seen in our institutions in 1980-2014. The study cohort was divided into two subgroups, comparing the main 2 therapeutic options [cyclophosphamide doxorubicin vincristine prednisone (CHOP) vs rituximab-CHOP (R-CHOP)]. A better outcome with immunochemotherapy (R-CHOP) was observed. In the next 2 mo, we will present the update of our study with the same basic conclusion.

MYC expression is associated with older age, common morphology, increased MYC copy number, and poorer prognosis in patients with ALK+ anaplastic large cell lymphoma

The role of MYC dysregulation has been studied extensively in B-cell lymphomas, but little is known about its significance in T cell lymphomas. This study, for the first time in the literature, assessed the clinicopathologic and prognostic significance of MYC expression in ALK+ anaplastic large cell lymphoma (ALCL) cases. Using ≥50% as the cutoff value for positive MYC expression by immunohistochemistry, 17 of 46 (37%) cases were MYC+. Patients with MYC+ tumors were older (median age, 39 versus 29 years, p = 0.04) and more often showed a common morphologic pattern (100% versus 69%, p = 0.02), when compared with those with MYC-negative tumors. By fluorescence in situ hybridization analysis, 9 of 31 (29%) cases showed increased MYC copy number, and 1 of 31 (3%) case had an MYC rearrangement, and the remaining 21 (68%) cases showed no MYC aberrations. Among the cases with increased MYC copy number, 5 of 8 (62%) cases showed MYC copy gain and/or amplification and 3 of 8 (38%) had polysomy 8. MYC expression was associated with increased MYC copy number (p = 0.01). MYC expression, but not increased MYC copy number, correlated with shorter overall survival (OS) (p = 0.03). In conclusion, MYC expression identified a distinct group of ALK + ALCL patients with more aggressive behavior and shorter OS. Our data suggest that MYC expression is an adverse prognostic factor and may be useful in stratifying or predicting the prognosis of patients with ALK+ ALCL.

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.

New MYC IHC Classifier Integrating Quantitative Architecture Parameters to Predict MYC Gene Translocation in Diffuse Large B-Cell Lymphoma

A new automated MYC IHC classifier based on bivariate logistic regression is presented. The predictor relies on image analysis developed with the open-source ImageJ platform. From a histologic section immunostained for MYC protein, 2 dimensionless quantitative variables are extracted: (a) relative distance between nuclei positive for MYC IHC based on euclidean minimum spanning tree graph and (b) coefficient of variation of the MYC IHC stain intensity among MYC IHC-positive nuclei. Distance between positive nuclei is suggested to inversely correlate MYC gene rearrangement status, whereas coefficient of variation is suggested to inversely correlate physiological regulation of MYC protein expression. The bivariate classifier was compared with 2 other MYC IHC classifiers (based on percentage of MYC IHC positive nuclei), all tested on 113 lymphomas including mostly diffuse large B-cell lymphomas with known MYC fluorescent in situ hybridization (FISH) status. The bivariate classifier strongly outperformed the “percentage of MYC IHC-positive nuclei” methods to predict MYC+ FISH status with 100% sensitivity (95% confidence interval, 94-100) associated with 80% specificity. The test is rapidly performed and might at a minimum provide primary IHC screening for MYC gene rearrangement status in diffuse large B-cell lymphomas. Furthermore, as this bivariate classifier actually predicts “permanent overexpressed MYC protein status,” it might identify nontranslocation-related chromosomal anomalies missed by FISH.

MYC/BCL2 Co-Expression Is a Stronger Prognostic Factor Compared With the Cell-of-Origin Classification in Primary CNS DLBCL

Primary central nervous system (CNS) diffuse large B-cell lymphoma (DLBCL) is a subtype of DLBCL with an unfavorable prognosis and a poor response to the treatment. As we know, DLBCL is stratified into germinal center B-cell (GCB)-like and activated B-cell (ABC)-like subtypes with different prognosis according to their gene-expression characteristics. In this study, we analyzed a case series of 77 patients with primary CNS DLBCL. A difference in prognosis of GCB-like and ABC-like subtypes was noticed, but no statistical significance was found. However, significant prognostic value of MYC/BCL2 co-expression was shown. The cases with MYC/BCL2 co-expression did not show any predominance of the 2 subtypes in our cases. Furthermore, patients with MYC/BCL2 co-expression had significantly worse overall survival for both cell of origin (COO) subtypes. We conjecture that MYC/BCL2 co-expression is associated with a poorer prognosis and is independent of COO classification. Moreover, the data suggest that MYC/BCL2 co-expression is superior to COO classification assessed by immunohistochemical analysis in patients with primary CNS DLBCL.

Primary central nervous system diffuse large B-cell lymphoma shows an activated B-cell-like phenotype with co-expression of C-MYC, BCL-2, and BCL-6

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma, whose main prognostic factor is closely related to germinal center B-cell-like subtype (GCB- DLBCL) or activated B-cell-like type (non-GCB-DLBCL). The most common type of primary central nervous system lymphoma is diffuse large B-cell type with poor prognosis and the reason is unclear. This study aims to stratify primary central nervous system diffuse large B-cell lymphoma (PCNS-DLBCL) according to the cell-of-origin (COO) and to investigate the multiple proteins expression of C-MYC, BCL-6, BCL-2, TP53, further to elucidate the reason why primary central nervous system diffuse large B-cell lymphoma possesses a poor clinical outcome as well. Nineteen cases of primary central nervous system DLBCL were stratified according to immunostaining algorithms of Hans, Choi and Meyer (Tally) and we investigated the multiple proteins expression of C-MYC, BCL-6, BCL-2, TP53. The Epstein-Barr virus and Borna disease virus infection were also detected. Among nineteen cases, most (15-17 cases) were assigned to the activated B-cell-like subtype, highly expression of C-MYC (15 cases, 78.9%), BCL-2 (10 cases, 52.6%), BCL-6 (15 cases, 78.9%). Unfortunately, two cases were positive for PD-L1 while PD-L2 was not expressed in any case. Two cases infected with BDV but no one infected with EBV. In conclusion, most primary central nervous system DLBCLs show an activated B-cell-like subtype characteristic and have multiple expressions of C-MYC, BCL-2, BCL-6 protein, these features might be significant factor to predict the outcome and guide treatment of PCNS-DLBCLs.

Relevance of Fusion Genes in Pediatric Cancers: Toward Precision Medicine

Pediatric cancers differ from adult tumors, especially by their very low mutational rate. Therefore, their etiology could be explained in part by other oncogenic mechanisms such as chromosomal rearrangements, supporting the possible implication of fusion genes in the development of pediatric cancers. Fusion genes result from chromosomal rearrangements leading to the juxtaposition of two genes. Consequently, an abnormal activation of one or both genes is observed. The detection of fusion genes has generated great interest in basic cancer research and in the clinical setting, since these genes can lead to better comprehension of the biological mechanisms of tumorigenesis and they can also be used as therapeutic targets and diagnostic or prognostic biomarkers. In this review, we discuss the molecular mechanisms of fusion genes and their particularities in pediatric cancers, as well as their relevance in murine models and in the clinical setting. We also point out the difficulties encountered in the discovery of fusion genes. Finally, we discuss future perspectives and priorities for finding new innovative therapies in childhood cancer.

Sole rearrangement but not amplification of MYC is associated with a poor prognosis in patients with diffuse large B cell lymphoma and B cell lymphoma unclassifiable

Rearrangement of MYC is associated with a poor prognosis in patients with diffuse large B cell lymphoma (DLBCL) and B cell lymphoma unclassifiable (BCLU), particularly in the setting of double hit lymphoma (DHL). However, little is known about outcomes of patients who demonstrate MYC rearrangement without evidence of BCL2 or BCL6 rearrangement (single hit) or amplification (>4 copies) of MYC. We identified 87 patients with single hit lymphoma (SHL), 22 patients with MYC-amplified lymphoma (MYC amp) as well as 127 DLBCL patients without MYC rearrangement or amplification (MYC normal) and 45 patients with DHL, all treated with either R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) or intensive induction therapy. For SHL and MYC amp patients, the 2-year progression-free survival rate (PFS) was 49% and 48% and 2-year overall survival rate (OS) was 59% and 71%, respectively. SHL patients receiving intensive induction experienced higher 2-year PFS (59% vs. 23%, P = 0·006) but similar 2-year OS as compared with SHL patients receiving R-CHOP. SHL DLBCL patients treated with R-CHOP, but not intensive induction, experienced significantly lower 2-year PFS and OS (P < 0·001 for both) when compared with MYC normal patients. SHL patients appear to have a poor prognosis, which may be improved with receipt of intensive induction.

Recent Advances in Aggressive Large B-cell Lymphomas: A Comprehensive Review

Diffuse large B-cell lymphoma (DLBCL) is an aggressive disease with considerable heterogeneity reflected in the 2008 World Health Organization classification. In recent years, genome-wide assessment of genetic and epigenetic alterations has shed light upon distinct molecular subsets linked to dysregulation of specific genes or pathways. Besides fostering our knowledge regarding the molecular complexity of DLBCL types, these studies have unraveled previously unappreciated genetic lesions, which may be exploited for prognostic and therapeutic purposes. Following the last World Health Organization classification, we have witnessed the emergence of new variants of specific DLBCL entities, such as CD30 DLBCL, human immunodeficiency virus-related and age-related variants of plasmablastic lymphoma, and EBV DLBCL arising in young patients. In this review, we will present an update on the clinical, pathologic, and molecular features of DLBCL incorporating recently gained information with respect to their pathobiology and prognosis. We will emphasize the distinctive features of newly described or emerging variants and highlight advances in our understanding of entities presenting a diagnostic challenge, such as T-cell/histiocyte-rich large B-cell lmphoma and unclassifiable large B-cell lymphomas. Furthermore, we will discuss recent advances in the genomic characterization of DLBCL, as they may relate to prognostication and tailored therapeutic intervention. The information presented in this review derives from English language publications appearing in PubMed throughout December 2015. For a complete outline of this paper, please visit: http://links.lww.com/PAP/A12.

Double hit lymphoma: from biology to therapeutic implications

INTRODUCTION

Diffuse large B-cell lymphoma (DLBCL) is a molecularly heterogeneous disease defined by different cellular origins and mechanisms of oncogenic activation. Approximately 10% of DLBCL cases harbor a MYC rearrangement and this has been associated with a more aggressive clinical course following standard therapy.

AREAS COVERED

So-called 'double-hit lymphomas' (DHL) or 'triple hit lymphomas' (THL) occur when MYC is concurrently rearranged with BCL2 and/or BCL6. These tumors are characterized by high proliferation rate and a very poor outcome following standard R-CHOP (rituximab, cyclophosphamide, doxorubicin vincristine and prednisone) therapy, in most (though not all) studies that have looked at this. Though there is a paucity of published experience with other chemotherapy regimens, there is emerging evidence that more intensive approaches may improve outcome. Recently, there has been a lot of focus in the literature on 'double-expresser lymphomas' (DEL) with high MYC, BCL2 and/or BCL6 expression but typically without rearrangements of these genes. These DEL cases, have a poor outcome with R-CHOP and there is little consensus on how they should be approached. Expert commentary: This review will focus on the biology and treatment of DHL and DEL, discuss the outcome of these diseases with current standard as well as promising new approaches and conclude with a section on novel agents that are in development for these diseases.

MYC or BCL2 copy number aberration is a strong predictor of outcome in patients with diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma (NHL). Patients with DLBCL harboring MYC aberrations concurrent with BCL2 or/and BCL6 aberrations constitute a specific group with extremely poor outcome. In this study, we retrospectively investigated the incidence and prognosis of MYC, BCL2, and BCL6 aberrations with DLBCL patients in Chinese population. We applied fluorescence in situ hybridization and immunohistochemical analysis in 246 DLBCL patients. The results showed that patients with MYC or BCL2 copy number aberration (CNA) had significantly worse overall survival (OS) and progression-free survival (PFS) than negative cases (P < 0.0001). Patients with both MYC and BCL2 CNA had similar outcomes to those with classic double hit lymphoma or protein double expression lymphoma (MYC and BCL2/BCL6 coexpression). By multivariate analysis, MYC CNA, BCL2 CNA and double CNA were the independent worse prognostic factors. In conclusions, patients with MYC or BCL2 CNA constituted a unique group with extremely poor outcome and may require more aggressive treatment regimens.

High-grade Transformation of Low-grade B-cell Lymphoma: Pathology and Molecular Pathogenesis

Patients with low-grade (clinically indolent) lymphomas are at risk to undergo transformation to high-grade (clinically aggressive) lymphoma, although transformation only occurs in a subset of patients. When transformation occurs it is a critical event that determines the course of disease and is associated with unfavorable patient outcomes. Accurate detection of transformation, predictive biomarkers, and identification of specific molecular pathways implicated in the pathobiology of transformation will facilitate personalized therapeutic approaches and underpin advances in clinical outcomes. In this article, we present an update of the clinical and pathologic diagnostic criteria for low-grade B-cell lymphoma transformation and discuss the molecular alterations involved in the pathogenesis of this biological phenomenon.

[Prognostic analysis of BCL-2/MYC double- hit in diffuse large B-cell lymphoma]

OBJECTIVE

To investigate the effect of BCL-2/MYC double-hit on prognosis in diffuse large B-cell lymphoma（DLBCL）.

METHODS

A retrospective study was conducted to investigate clinical and pathological data of 111 patients with DLBCL. CD10, BCL-6, MUM-1, BCL-2 protein expressions were examined by immune-histochemical methods, and abnormal BCL-2 and MYC genes were analyzed by FISH for patients with sufficient pathological data. SAS 8.2 was adopted to perform Chi- square test, COX's proportional Hazard Model, Life table survival analyses.

RESULTS

Of 111 patients, male 77 cases, female 34 cases, the median age was 55（14-85）years, CD10, BCL-6, MUM-1, BCL-2 positive rates were 15.7%（16/102）, 58.8%（60/102）, 33.0%（34/103）, 74.8（77/103）respectively, the abnormal rate of BCL-2 gene was 43.1%（25/58, 24 cases with multiple copies, 1 case with translocation）, and the abnormal rate of MYC gene was 20.4%（10/49, 10 cases with multiple copies）. Coexistence of BCL-2 and MYC genes abnormalities accounted for 13.0%（6/46）. According to the classification of Hans model, GCB subgroup accounted for 41.2%（42/102）, and non-GCB subgroup 58.8%（60/102）, the median survival time was 24 months, 3-year and 5-year overall survival rates were 48.5% and 39.7% respectively. Overall survival rates of normal and abnormal BCL-2 gene were 34.2%，22.8%, respectively with no statistical significance（P=0.770）. Overall survival rates of normal and abnormal MYC gene were 35.9% and 22.2% ，with no statistical significance（P=0.650）. Overall survival rate of double-hit was 0, far worse than that of single abnormal gene（P=0.034）, which implied double-hit of BCL-2 and MYC gene abnormality to be adverse prognostic factors. BCL-6 protein express could be classified as benign prognostic factors, while ECOG score≥2, escalated IPI index as adverse prognostic factors, and further COX risk model regression analysis indicated that ECOG score, IPI grading and treatment methods were independently adverse factors affecting prognosis. Comprehensive therapy based on chemotherapy could improve outcome.

CONCLUSION

BCL-2/MYC genes double-hit was the factor for the adverse outcome in DLBCL patients. However, ECOG score, IPI risk grading and treatment methods were the independent factors affecting prognosis.

Routine conventional karyotyping of lymphoma staging bone marrow samples does not contribute clinically relevant information

Bone marrow (BM) evaluation is an important part of lymphoma staging, which guides patient management. Although positive staging marrow is defined as morphologically identifiable disease, such samples often also include flow cytometric analysis and conventional karyotyping. Cytogenetic analysis is a labor-intensive and costly procedure and its utility in this setting is uncertain. We retrospectively reviewed pathological reports of 526 staging marrow specimens in which conventional karyotyping had been performed. All samples originated from a single institution from patients with previously untreated Hodgkin and non-Hodgkin lymphomas presenting in an extramedullary site. Cytogenetic analysis revealed clonal abnormalities in only eight marrow samples (1.5%), all of which were positive for lymphoma by morphologic evaluation. Flow cytometry showed a small clonal lymphoid population in three of the 443 morphologically negative marrow samples (0.7%). Conventional karyotyping is rarely positive in lymphoma staging marrow samples and, in our cohort, the BM karyotype did not contribute clinically relevant information in the vast majority of cases. Our findings suggest that karyotyping should not be performed routinely on BM samples taken to stage previously diagnosed extramedullary lymphomas unless there is pathological evidence of BM involvement by lymphoma.

Isolated MYC cytogenetic abnormalities in diffuse large B-cell lymphoma do not predict an adverse clinical outcome

In this study, we investigated the significance of MYC, BCL2 and BCL6 gene abnormalities in a cohort of 205 diffuse large B-cell lymphoma (DLBCL) patients studied by conventional and/or fluorescence in situ hybridization cytogenetic analysis. Combining these methods, 172 cases (84%) were classified as MYC-, 17 (8%) were MYC+/BCL2-/BCL6-, and 16 (8%) were double/triple-hit lymphomas (i.e. MYC+/BCL2+, MYC+/BCL6+, or MYC+/BCL2+/BCL6+). We found a significant difference in event-free survival (EFS) among the three groups (p = 0.02), with the double/triple-hit group having the worst EFS. Patients who were MYC+, but BCL2- and BCL6-, had the best EFS. We conclude that patients with MYC+ DLBCL, but without BCL2 or BCL6 abnormalities, do not have a worse outcome when compared to those who are MYC-. However, patients with double/triple-hit DLBCL have a very poor outcome and should be treated with aggressive or novel therapies.

Practical Applications in Immunohistochemistry: Evaluation of Diffuse Large B-Cell Lymphoma and Related Large B-Cell Lymphomas

Context

Diffuse large B-cell lymphoma is the most commonly diagnosed subtype of lymphoma worldwide. The current World Health Organization (WHO) classification includes several subtypes, based on a combination of clinical, immunohistochemical, and genetic differences. Immunohistochemical staining is essential in evaluating diffuse large B-cell lymphoma and many related large B-cell lymphomas and aggressive B-cell lymphomas.

Objective

To address different immunohistochemical features used for identification, subclassification, prognosis and in some cases, therapy, of diffuse large B-cell lymphoma and related lymphomas.

Data Sources

The information outlined in this review article is based on our experiences with routine cases, on the current WHO classification of hematopoietic and lymphoid tumors, and on a review of English-language articles published throughout 2014.

Conclusions

Features and diagnostic criteria of diffuse large B-cell lymphoma, aggressive variants of B-cell lymphomas, including Burkitt lymphoma and “double-hit” lymphomas, are discussed. Identification of cell of origin (germinal center type versus activated B-cell type) is discussed at length. Finally, practical approaches for diagnosis are discussed.

MYC protein expression in primary diffuse large B-cell lymphoma of the central nervous system

Primary diffuse large B-cell lymphoma of the central nervous system (CNS DLBCL) is a rare, aggressive subtype of DLBCL, the biology of which is poorly understood. Recent studies have suggested a prognostic role of MYC protein expression in systemic DLBCL, but little is known about the frequency and significance of MYC protein expression in CNS DLBCL. Hence, we investigated MYC protein expression profiles of CNS DLBCL and assessed the relationship between MYC expression and a variety of histopathologic, immunophenotypic, genetic, and clinical features. Fifty-nine CNS DLBCL diagnosed at our institution over the past 13 years were evaluated. The majority of cases (80%) showed centroblastic morphology, and 12 (20%) displayed a perivascular pattern of infiltration. According to the Hans criteria, 41 (69%) cases had a non-germinal center B-cell and 18 (31%) had a germinal center B-cell cell-of-origin (COO) phenotype. Mean MYC protein expression was 50% (median: 50%, range: 10-80%). Forty-three cases (73%) showed MYC overexpression (≥ 40%), and 35 (60%) showed MYC/BCL2 coexpression. MYC overexpression was seen in the single case harboring MYC translocation and in the cases showing increased copies of MYC (27%); however, no significant difference in mean MYC expression was seen between groups harboring or lacking MYC aberrations. In our series, age was associated with a significantly increased risk of death, and the perivascular pattern of infiltration was associated with a significantly increased risk of disease progression. Neither MYC expression (with or without BCL2 coexpression) nor other variables, including COO subtype were predictive of clinical outcome. Our findings indicate that the proportion of CNS DLBCL overexpressing MYC is higher compared to systemic DLBCL, and MYC overexpression appears to be independent of genetic MYC abnormalities. Thus, MYC expression and other immunophenotypic markers used for prognostication of systemic DLBCL might not apply to CNS DLBCL due to differences in disease biology.

Ongoing challenge of optimal patient selection for CNS prophylaxis in patients with non-Hodgkin lymphoma

SUMMARY 

CNS relapse is a devastating and frequently lethal complication in patients with lymphoma, and selecting patients to receive CNS-directed prophylaxis is a common and frequently challenging decision for the clinician. Histologic subtype, anatomic location, molecular and clinical risk factors may all be used to stratify patients for CNS risk. In this paper we focus on these issues and attempt to provide practical guidance for the clinician in selecting which patients with lymphoma may benefit from CNS prophylaxis.