MYC translocation partner gene determines survival of patients with large B-cell lymphoma with MYC- or double-hit MYC/BCL2 translocations

Imatinib mesylate reduces c-MYC expression in double-hit lymphoma cells by suppressing inducible cytidine deaminase

BACKGROUND

Double-hit lymphoma (DHL) with c-MYC gene translocation is highly aggressive and has a poor prognosis. In DHL cells, activation-induced cytidine deaminase (AID) promotes antibody class switch recombination (CSR), ultimately leading to c-MYC gene translocation caused by Myc/IgH DNA double-strand breaks. However, currently there is still no method to suppress the expression of AID.

METHODS

In this study, we compared the clinical significance of AID expression in DHL, Additionally, two human double-hit lymphoma cell lines were used to analyze the effect of imatinib mesylate on c-MYC in vitro, and the therapeutic effect was also evaluated in xenograft mouse models.

RESULTS

Imatinib mesylate downregulated the AID and c-MYC proteins in patients with chronic myelogenous leukemia associated with DHL. In addition, imatinib mesylate reduced AID and c-MYC expression in SU-DHL-4 and OCI-Ly18 DHL cells. Imatinib mesylate exerted significant inhibitory effects on the proliferation and metastasis of SU-DHL-4 and OCI-Ly18 cells. Finally, imatinib mesylate reduced not only tumor burden in DHL mouse models, but also AID and c-MYC expression in vivo.

CONCLUSION

These findings reveal that imatinib mesylate effectively reduces the carcinogenic function of c-MYC in DHL, providing novel strategies for developing therapies targeting c-MYC-driven DHL.

Characteristics and Clinical Value of MYC , BCL2, and BCL6 Rearrangement Detected by Next-generation Sequencing in DLBCL

MYC , BCL2, and BCL6 rearrangements are clinically important events of diffuse large B-cell lymphoma (DLBCL). The ability and clinical value of targeted next-generation sequencing (NGS) in the detection of these rearrangements in DLBCL have not been fully determined. We performed targeted NGS (481-gene-panel) and break-apart FISH of MYC , BCL2, and BCL6 gene regions in 233 DLBCL cases. We identified 88 rearrangements (16 MYC ; 20 BCL2 ; 52 BCL6 ) using NGS and 96 rearrangements (28 MYC ; 20 BCL2 ; 65 BCL6 ) using FISH. The consistency rates between FISH and targeted NGS for the detection of MYC , BCL2, and BCL6 rearrangements were 93%, 97%, and 89%, respectively. FISH-cryptic rearrangements (NGS+/FISH-) were detected in 7 cases (1 MYC ; 3 BCL2 ; 2 BCL6 ; 1 MYC::BCL6 ), mainly caused by small chromosomal insertions and inversions. NGS-/FISH+ were detected in 38 cases (14 MYC ; 4 BCL2 ; 20 BCL6 ).To clarify the cause of the inconsistencies, we selected 17 from the NGS-/FISH+ rearrangements for further whole genome sequencing (WGS), and all 17 rearrangements were detected with break points by WGS. These break points were all located outside the region covered by the probe of targeted NGS, and most (16/17) were located in the intergenic region. These results indicated that targeted NGS is a powerful clinical diagnostics tool for comprehensive MYC , BCL2, and BCL6 rearrangement detection. Compared to FISH, it has advantages in describing the break point distribution, identifying uncharacterized partners, and detecting FISH-cryptic rearrangements. However, the lack of high-sensitivity caused by insufficient probe coverage is the main limitation of the current technology.

Motive and opportunity: MYC rearrangements in high-grade B-cell lymphoma with MYC and BCL2 rearrangements (an LLMPP study)

ABSTRACT

Rearrangements that place the oncogenes MYC, BCL2, or BCL6 adjacent to superenhancers are common in mature B-cell lymphomas. Lymphomas with diffuse large B-cell lymphoma (DLBCL) or high-grade morphology with both MYC and BCL2 rearrangements are classified as high-grade B-cell lymphoma with MYC and BCL2 rearrangements ("double hit"; HGBCL-DH-BCL2) and are associated with aggressive disease and poor outcomes. Although it is established that MYC rearrangements involving immunoglobulin (IG) loci are associated with inferior outcomes relative to those involving other non-IG superenhancers, the frequency of and mechanisms driving IG vs non-IG MYC rearrangements have not been elucidated. Here, we used custom targeted capture and/or whole-genome sequencing to characterize oncogene rearrangements across 883 mature B-cell lymphomas including Burkitt lymphoma, follicular lymphoma, DLBCL, and HGBCL-DH-BCL2 tumors. We demonstrate that, although BCL2 rearrangement topology is consistent across entities, HGBCL-DH-BCL2 have distinct MYC rearrangement architecture relative to tumors with single MYC rearrangements or with both MYC and BCL6 rearrangements (HGBCL-DH-BCL6), including both a higher frequency of non-IG rearrangements and different architecture of MYC::IGH rearrangements. The distinct MYC rearrangement patterns in HGBCL-DH-BCL2 occur on the background of high levels of somatic hypermutation across MYC partner loci in HGBCL-DH-BCL2, creating more opportunity to form these rearrangements. Furthermore, because 1 IGH allele is already disrupted by the existing BCL2 rearrangement, the MYC rearrangement architecture in HGBCL-DH-BCL2 likely reflects selective pressure to preserve both BCL2 and B-cell receptor expression. These data provide new mechanistic explanations for the distinct patterns of MYC rearrangements observed across different lymphoma entities.

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.

Distribution and clinical impact of molecular subtypes with dark zone signature of DLBCL in a Japanese real-world study

The distribution and clinical impact of cell-of-origin (COO) subtypes of diffuse large B-cell lymphoma (DLBCL) outside Western countries remain unknown. Recent literature also suggests that there is an additional COO subtype associated with the germinal center dark zone (DZ) that warrants wider validation to generalize clinical relevance. Here, we assembled a cohort of Japanese patients with untreated DLBCL and determined the refined COO subtypes, which include the DZ signature (DZsig), using the NanoString DLBCL90 assay. To compare the distribution and clinical characteristics of the molecular subtypes, we used a data set from the cohort of British Columbia Cancer (BCC) (n = 804). Through the 1050 patient samples on which DLBCL90 assay was successfully performed in our cohort, 35%, 45%, and 6% of patients were identified to have germinal center B-cell-like (GCB) DLBCL, activated B-cell-like (ABC) DLBCL, and DZsig-positive (DZsigpos) DLBCL, respectively, with the highest prevalence of ABC-DLBCL, differing significantly from the BCC result (P < .001). GCB-DLBCL, ABC-DLBCL, and DZsigpos-DLBCL were associated with 2-year overall survival rates of 88%, 75%, and 66%, respectively (P < .0001), with patients with DZsigpos-DLBCL having the poorest prognosis. In contrast, GCB-DLBCL without DZsig showed excellent outcomes after rituximab-containing immunochemotherapy. DZsigpos-DLBCL was associated with the significant enrichment of tumors with CD10 expression, concurrent MYC/BCL2 expression, and depletion of microenvironmental components (all, P < .05). These results provide evidence of the distinct distribution of clinically relevant molecular subtypes in Japanese DLBCL and that refined COO, as measured by the DLBCL90 assay, is a robust prognostic biomarker that is consistent across geographical areas.

Cytogenomics of B-cell non-Hodgkin lymphomas: The "old" meets the "new"

For the routine diagnosis of haematological neoplasms an integrative approach is used considering the morphology, and the immunophenotypic, and molecular features of the tumor sample, along with clinical information. The identification and characterization of recurrent chromosomal aberrations mainly detected by conventional and molecular cytogenetics in the tumor cells has a major impact on the classification of lymphoid neoplasms. Some of the B-cell non-Hodgkin lymphomas are characterized by particular chromosomal aberrations, highlighting the relevance of conventional and molecular cytogenetic studies in their diagnosis and prognosis. In the current genomics era, next generation sequencing provides relevant information as the mutational profiles of haematological malignancies, improving their classification and also the clinical management of the patients. In addition, other new technologies have emerged recently, such as the optical genome mapping, which can overcome some of the limitations of conventional and molecular cytogenetics and may become more widely used in the cytogenetic laboratories in the upcoming years. Moreover, epigenetic alterations may complement genetic changes for a deeper understanding of the pathogenesis underlying B-cell neoplasms and a more precise risk-based patient stratification. Overall, here we describe the current state of the genomic data integrating chromosomal rearrangements, copy number alterations, and somatic variants, as well as a succinct overview of epigenomic changes, which altogether constitute a comprehensive diagnostic approach in B-cell non-Hodgkin lymphomas.

Emerging entities: high-grade/large B-cell lymphoma with 11q aberration, large B-cell lymphoma with IRF4 rearrangement, and new molecular subgroups in large B-cell lymphomas. A report of the 2022 EA4HP/SH lymphoma workshop

Emerging entities and molecular subgroups in large B-cell lymphomas (LBCLs) were discussed during the 2022 European Association for Haematopathology/Society for Hematopathology workshop in Florence, Italy. This session focused on newly recognized diseases and their diagnostic challenges. High-grade/large B-cell lymphoma with 11q aberration (HG/LBCL-11q) is defined by chromosome 11q-gains and telomeric loss. FISH analysis is recommended for the diagnosis. HG/LBCL-11q can occur in the setting of immunodeficiency, including ataxia-telangiectasia, and predominates in children. The morphological spectrum of these cases is broader than previously thought with often Burkitt-like morphology and coarse apoptotic bodies. It has a Burkitt-like immunophenotype (CD10+, BCL6+, BCL2-) but MYC expression is weak or negative, lacks MYC rearrangement, and is in contrast to Burkitt lymphoma 50% of the cases express LMO2. LBCL with IRF4 rearrangement (LBCL-IRF4) occurs mainly in the pediatric population but also in adults. LBCL-IRF4 has an excellent prognosis, with distinguishing molecular findings. IRF4 rearrangements, although characteristic of this entity, are not specific and can be found in association with other chromosomal translocations in other large B-cell lymphomas. Other molecular subgroups discussed included primary bone diffuse large B-cell lymphoma (PB-DLBCL), which has distinctive clinical presentation and molecular findings, and B-acute lymphoblastic leukemia (B-ALL) with IGH::MYC translocation recently segregated from Burkitt lymphoma with TdT expression. This latter disorder has molecular features of precursor B-cells, often tetrasomy 1q and recurrent NRAS and KRAS mutations. In this report, novel findings, recommendations for diagnosis, open questions, and diagnostic challenges raised by the cases submitted to the workshop will be discussed.

Integration of molecular testing for the personalized management of patients with diffuse large B-cell lymphoma and follicular lymphoma

Diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) are the most common forms of aggressive and indolent lymphoma, respectively. The majority of patients are cured by standard R-CHOP immunochemotherapy, but 30%–40% of DLBCL and 20% of FL patients relapse or are refractory (R/R). DLBCL and FL are phenotypically and genetically hereterogenous B-cell neoplasms. To date, the diagnosis of DLBCL and FL has been based on morphology, immunophenotyping and cytogenetics. However, next-generation sequencing (NGS) is widening our understanding of the genetic basis of the B-cell lymphomas. In this review we will discuss how integrating the NGS-based characterization of somatic gene mutations with diagnostic or prognostic value in DLBCL and FL could help refine B-cell lymphoma classification as part of a multidisciplinary pathology work-up. We will also discuss how molecular testing can identify candidates for clinical trials with targeted therapies and help predict therapeutic outcome to currently available treatments, including chimeric antigen receptor T-cell, as well as explore the application of circulating cell-free DNA, a non-invasive method for patient monitoring. We conclude that molecular analyses can drive improvements in patient outcomes due to an increased understanding of the different pathogenic pathways affected by each DLBCL subtype and indolent FL vs R/R FL.

Genetic Profiling in Diffuse Large B-Cell Lymphoma: The Promise and the Challenge

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma. Over the previous 2 decades, tremendous progress has been made in our understanding of the molecular pathogenesis of DLBCL. However, this biological understanding has not yet been translated into improved first-line therapy. A major barrier to the introduction of molecularly targeted therapy in DLBCL is the considerable molecular heterogeneity of this disease. Recent studies have tried to rationalize this heterogeneity by proposing new genetic subtypes of DLBCL. Although remarkable consensus exists over the broad nature of these genetic subtypes, important questions remain over precisely how, or even why, genetic subtyping might be incorporated into diagnostic laboratories. In this review, we compare the findings of the major genetic subtyping studies and discuss the implications this may have for diagnostic pathology services and the management of DLBCL.

Extra copy number of BCL2 is correlated with increased BCL-2 protein expression and poor survival in diffuse large B-cell lymphoma treated with chemoimmunotherapy

The clinical significance of extra copy (EC) genotypes of BCL2, MYC, and BCL6 have not been fully elucidated. We evaluated the EC and translocation statuses of BCL2, MYC, and BCL6 in 190 diffuse large B-cell lymphoma (DLBCL) cases using fluorescence in situ hybridization. EC genotype was sub-classified according to copy number-gained tumor cell ratio (EC1, >20% but ≤50%; EC2, >50%). Only the BCL2-EC groups, not MYC-EC or BCL6-EC groups, displayed significantly increased immunoreactivity of the corresponding protein. Moreover, the BCL2-EC2 group was significantly associated with poor overall survival (OS) and progression-free survival (PFS) in a 147 R-CHOP-treated patient subset, which was also statistically significant as per the multivariate survival analysis for PFS. No significant differences in the survival of MYC, BCL6, concurrent BCL2/MYC, BCL6/MYC, BCL2/BCL6, or triple EC groups were observed. BCL2-EC may contribute to increased BCL-2 protein expression and serve as a predictor of treatment outcomes in DLBCL.

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.

A Combined Biomarker of Bright CD38 and MYC ≥55% Is Highly Predictive of Double-/Triple-Hit High-Grade B-Cell Lymphoma

OBJECTIVES

Diagnosis of high-grade B-cell lymphoma with MYC and BCL2 or BCL6 rearrangements (double-/triple-hit lymphoma [DTHL]) appears to mandate fluorescence in situ hybridization (FISH) testing for all large B-cell lymphoma (LBCL). Given the low incidence of DTHL, we aimed to identify flow cytometry (FC) and immunohistochemistry (IHC) features of DTHL that could be used to develop an optimal screening strategy. This combined FC-IHC approach has not yet been studied.

METHODS

We compared features of 40 cases of DTHL and 39 cases of diffuse LBCL (DLBCL) without MYC rearrangement.

RESULTS

Bright CD38 expression (CD38bright) by FC, high MYC expression (≥55%), and double-expressor phenotype by IHC were significantly associated with DTHL. The biomarker combining FC and IHC, CD38bright and/or MYC ≥55%, was superior to FC and IHC markers alone in predicting DTHL. Restricting FISH testing to approximately 25% of LBCL based on CD38brightand/or MYC ≥55% would detect approximately 95% of DTHL-BCL2 and approximately 75% of DHL-BCL6.

CONCLUSIONS

Our study demonstrated that the novel biomarker of CD38bright and/or MYC ≥55% is highly predictive of DTHL. Awareness of the advantages and limitations of this screening strategy would facilitate development of a rational diagnostic workflow to provide high-quality patient care.

Impact of timing and precision of histopathological diagnosis on outcomes of patients with Burkitt lymphoma and high-grade B-cell lymphoma

BACKGROUND

Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL) are aggressive B-cell non-Hodgkin lymphomas (B-NHL) with a generally favorable prognosis after immunochemotherapy. The outcome of BL is superior to DLBCL. In 2016, a distinct group of lymphomas displaying characteristics of both BL and DLBCL (high grade B-cell lymphoma, HGBL) was introduced into the WHO classification. Histopathological discrimination of BL, DLBCL, and HGBL may be challenging. Data on the frequency of histopathological difficulties resulting in revision of the final diagnosis of BL/DLBCL/HGBL and its impact on the prognosis are limited.

METHODS

We assessed histopathological features and clinical outcomes of 66 patients with suspected diagnosis of BL at the reporting institution between 2010 and 2020.

RESULTS

The median age was 51 years (range 19-82) and final histopathological diagnosis revealed BL (n = 40), DLBCL (n = 12), or HGBL (n = 14). Patients with DLBCL and HGBL were either treated with DLBCL-directed (83.3% and 35.7%) or BL-directed (16.7% and 64.3%) protocols. Patients in whom diagnosis was revised from DLBCL to BL after initiation of DLBCL-directed treatment had a significantly inferior progression-free survival (PFS) than patients initially diagnosed with BL (p = 0.045), thus resembling rather the prognosis of DLBCL/HGBL. There was no difference between patients with DLBCL and HGBL, respectively, regarding PFS and OS (p = 0.38 and p = 0.27).

CONCLUSION

These results suggest that timely and precise histopathological diagnosis as well as reference histopathological review of the underlying lymphoma is critical to determine up-front treatment strategies. Consequently, selection of more aggressive treatment protocols in case of difficulties with discrimination between DLBCL/HGBL/BL may be a reasonable approach.

Fitting double-hit lymphoma into the aggressive lymphoma spectrum: a square peg in a round hole?

High-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements or both, commonly called double-hit lymphoma (DHL), is an aggressive B-cell lymphoma that is molecularly distinct from diffuse large B-cell lymphoma (DLBCL) and is associated with poor outcomes. Recent advances in the molecular classification of DLBCL have identified distinct subsets, including genetic signatures which correlate with DHL and survival. DHL with concomitant TP53 mutation appears to be associated with a very poor prognosis. Standard chemo-immunotherapy is not an effective treatment for these patients and personalized, innovative strategies are needed. In this review, we summarize recent advances in the subclassification of DLBCL, with a focus on DHL. We also incorporate early, promising clinical trial data using CAR T and targeted therapies. Rationally designed clinical trials for DLBCL are needed to advance the care of patients with DHL and other adverse risk DLBCL subgroups.

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.

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.

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.

Relative frequency and clinicopathologic characteristics of MYC-rearranged follicular lymphoma

MYC rearrangement is a relatively rare genetic abnormality in follicular lymphoma (FL). In this study, we evaluated the relative frequency of MYC rearrangement in 522 cases of FL and studied their clinicopathologic, cytogenetic, and molecular characteristics. Fluorescence in situ hybridization studies for MYC (break-apart probe), MYC/IGH, IGH/BCL2, and BCL6 rearrangements were performed on tissue microarrays. Immunohistochemical stains for CD10, BCL2, BCL6, and MYC were performed and scored on MYC-rearranged cases. On 4 FL cases, a custom targeted panel of 356 genes was used for mutation analysis. Ten cases (1.9%) were positive for MYC rearrangement. Histologically, 6 of 10 cases were grade 1-2, and 4 cases were grade 3A. By immunohistochemistry, 9 of 9 tested cases were CD10+, all cases were BCL6+, and 9/10 cases were BCL2+. MYC protein staining was low in all cases tested. IGH/BCL2 rearrangement was detected in 5 of 9 cases, whereas BCL6 rearrangement was detected in 3 of 7 tested cases and 4 of 10 cases showed MYC/IGH rearrangement. The most commonly detected mutations in the MYC-positive cases included HLA-B, TNFRSF14, and KMT2D. MYC and/or B2M abnormalities were detected in 2 cases. In conclusion, MYC rearrangement is uncommon in FL and these cases do not appear to have specific histologic characteristics. Molecular analysis showed abnormalities in genes associated with transformation, namely MYC and B2M. Larger studies are needed to evaluate if MYC-rearrangement in FL has prognostic significance.

Precursor B-Cell Acute Lymphoblastic Leukemia With MYC and BCL2 Rearrangements Presenting as Extensive Extranodal Disease in an Adolescent

Combined rearrangements of MYC and BCL2 are rare in precursor B-cell acute lymphoblastic leukemia (B-ALL). A 14-year-old boy presented with swelling of the knee and face. Imaging revealed diffuse infiltration of lacrimal glands, parotid glands along with the extensive epidural disease. Morphology and immunophenotype of knee joint aspirate were consistent with precursor B-ALL. Fluorescent in situ hybridization identified rearrangements of MYC and BCL2 genes. The disease was refractory to intensive treatment. The patient died of progressive disease. Precursor B-ALL with combined MYC and BCL2 rearrangements is rare, characterized by an aggressive clinical course, and has an inadequate response to standard therapeutic approaches.

[The incidence of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements in diffuse large B-cell lymphoma]

Objective: To investigate the incidence of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangement in Chinese diffuse large B-cell lymphoma (DLBCL) . Methods: From January 2013 to August 2020, 922 DLBCL cases were collected. C-MYC and BCL2 protein expression levels were analyzed by immunohistochemistry staining. Fluorescence in situ hybridization was used to detect the structural abnormalities of MYC, BCL2, and BCL6, including gene breaks and copy number changes. Results: MYC and BCL2 and/or BCL6 gene breaks were found in 29 out of 922 DLBCL cases (3.15%) , including 25 cases of double-hit lymphoma (DHL; 14 cases involving MYC and BCL2 rearrangements and 11 cases involving MYC and BCL6 rearrangements) and four cases involving MYC, BCL2, and BCL6 rearrangements, referring to triple-hit lymphoma. According to the threshold of C-MYC ≥40% and BCL2 ≥50%, 541 cases (58.68%) overexpressed C-MYC and BCL2 proteins, including 22 DHL cases. Moreover, according to the threshold of C-MYC ≥70% and BCL2 ≥50%, 52 cases (5.64%) overexpressed C-MYC and BCL2 proteins, including nine DHL cases. The P53 protein expression was detected by immunohistochemistry staining. The mutant P53 expression pattern was shown in 101 out of 709 cases (14.25%) , whereas 13 cases (1.83%) were negative, likely indicating P53 gene fragment deletion. Conclusion: The incidence of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements was low in DLBCLs, and no significant correlation between gene abnormality and protein overexpression was shown. The correct diagnosis of DHL depends on molecular genetic detection.

High-grade B-cell lymphomas with MYC and BCL2 translocations lack tumor-associated macrophages and PD-L1 expression: A possible noninflamed subgroup

We investigated the intratumoral source of PD-L1 expression and the infiltration of tumor-associated macrophages (TAMs) in large B-cell lymphomas (LBCLs) with or without MYC-translocation, as well as possible correlations to BCL2-and BCL6-translocations and cell of origin (COO). One-hundred and twenty-six patient samples were studied in a cohort enriched for MYC-translocated tumors with 34 samples carrying this translocation. Demonstration of intratumoral distribution and cellular source of PD-L1 was enabled by immunohistochemical (IHC) dual staining specifically highlighting PD-L1 expression in lymphoma B-cells with antibodies against PD-L1 and PAX5. Additional IHC with antibodies against CD68 and CD163 identified TAMs. We found that CD68-positive TAMs were the main source of PD-L1 protein expression in contrast to lymphoma B cells which rarely expressed PD-L1. Semiquantitative IHC demonstrated a significant correlation between CD68 and PD-L1 protein expression. Unsupervised hierarchical analysis of PD-L1, CD68, and CD163 IHC data subsequently demonstrated three potential clusters defined by expression of the three biomarkers. Cluster A consisted of patient samples with significantly lower expression of PD-L1, CD68, and CD163, but also significantly higher prevalence of BCL2-translocation and MYC-BCL2-double-hit (DH) compared to the other two clusters. In cluster C we found a significant accumulation of BCL6 translocated tumors. This cluster in contrast had the highest protein expression of PD-L1, CD68, and CD163. Cluster B tumors had an intermediate expression of the three biomarkers, but no accumulation of the specific genetic translocations. Our data, which were based on morphological analysis, immunophenotyping and genotyping by fluorescence in situ hybridization were in line with new concepts of LBCL taxonomy integrating genetic, phenotypical, and immunological characteristics with identification of new subgroups where MYC translocation and MYC-BCL2 DH may identify a noninflamed subtype. These findings may furthermore hold significant predictive value especially regarding immune checkpoint blockade therapy, but further molecular characterization should be done to substantiate this hypothesis.

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.

Impact of Genetics on Mature Lymphoid Leukemias and Lymphomas

Recurrent genetic aberrations have long been recognized in mature lymphoid leukemias and lymphomas. As conventional karyotypic and molecular cloning techniques evolved in the 1970s and 1980s, multiple cytogenetic aberrations were identified in lymphomas, often balanced translocations that juxtaposed oncogenes to the immunoglobulin (IG) or T-cell receptor (TR) loci, leading to dysregulation. However, genetic characterization and classification of lymphoma by conventional cytogenetic methods is limited by the infrequent occurrence of recurrent karyotypic abnormalities in many lymphoma subtypes and by the frequent difficulty in growing clinical lymphoma specimens in culture to obtain informative karyotypes. As higher-resolution genomic techniques developed, such as array comparative genomic hybridization and fluorescence in situ hybridization, many recurrent copy number changes were identified in lymphomas, and copy number assessment of interphase cells became part of routine clinical practice for a subset of diseases. Platforms to globally examine mRNA expression led to major insights into the biology of several lymphomas, although these techniques have not gained widespread application in routine clinical settings. With the advent of next-generation sequencing (NGS) techniques in the early 2000s, numerous insights into the genetic landscape of lymphomas were obtained. In contrast to the myeloid malignancies, most common lymphomas exhibit an at least somewhat mutationally complex genome, with few single driver mutations in the majority of patients. However, many recurrently mutated pathways have been identified across lymphoma subtypes, informing targeted therapeutic approaches that are beginning to make meaningful changes in the treatment of lymphoma. In addition to the ability to identify possible therapeutic targets, NGS techniques are highly amenable to the tracking of residual lymphoma following therapy, because of the presence of unique genetic "fingerprints" in lymphoma cells due to V(D)-J recombination at the antigen receptor loci. This review will provide an overview of the impact of novel genetic technologies on lymphoma classification, biology, and therapy.

Hematopoietic stem cell transplantation for diffuse large B-cell lymphoma having 8q24/MYC rearrangement in Japan

The prognosis of diffuse large B-cell lymphoma (DLBCL) having MYC rearrangement (MYC-R), including double hit lymphoma (DHL), is poor by standard immunochemotherapy. To evaluate the significance of hematopoietic stem cell transplantation (SCT) for DLBCL with MYC-R, we retrospectively analyzed Japanese SCT registry data. In total, 54 patients with DLBCL with MYC-R were identified from 4336 registered adult DLBCL patients. Detailed clinical and cytogenetic information was obtained for 48 patients. The median age at diagnosis of the 48 patients was 54.5 (range 21-67) years. Twenty-six (54%) patients had MYC-R only (single hit), and 22 (46%) had MYC-R and BCL2, and/or BCL6 rearrangement (double/triple hit). In 12 patients who received auto-SCT during the first complete response (CR), both the 2-year overall survival (OS) and progression-free survival (PFS) rates were 75.0% (95% confidence interval [CI], 40.8%-91.2%). In 20 patients who received auto-SCT after relapsed or refractory state, the 2-year OS and PFS rates were 68.2% (95% CI, 41.9%-84.5%) and 59.6% (95% CI, 35.1%-77.4%), respectively. In 17 patients who received allo-SCT, only 4 patients underwent SCT in CR. The 2-year OS and PFS rates were 29.4% (95% CI, 10.7%-51.1%) and 17.6% (95% CI, 4.3%-38.3%), respectively. The rate of non-relapse mortality at 1 year was 41.2% (95% CI, 17.1%-64.0%) in this group. The outcomes of single hit and double or triple hit were not different. These findings suggest that auto-SCT may be effective for MYC-R DLBCL, including DHL patients of chemosensitive relapsed or refractory state. Since most patients received allo-SCT not in CR, the outcome of allo-SCT was unsatisfactory due to high non-relapse mortality and early relapse. To clarify the role of allo-SCT for MYC-R DLBCL, further accumulation of patients is necessary.

Identification of high-risk monomorphic post-transplant lymphoproliferative disorder following solid organ transplantation

Monomorphic post-transplant lymphoproliferative disorder (M-PTLD) occurring after solid organ transplant histologically resembles aggressive non-Hodgkin lymphomas, with diffuse large B-cell lymphoma being the most common. In a cohort of 40 patients with DLBCL-type M-PTLD, inferior progression free survival (PFS) was observed for Revised International Prognostic Index (R-IPI) >2 (p = 0.01) and high-risk pathologic features (p = 0.02), defined by double expressor lymphoma, MYC rearrangement, or increased copy number of either MYC or BCL2. Overall survival (OS) was inferior in R-IPI >2 (p = 0.002) and high-risk pathologic features (p = 0.003). Combining both R-IPI >2 and high-risk pathologic features resulted in well-delineated good, intermediate, and poor risk groups of DLBCL-type M-PTLD with respect to both PFS and OS (p < 0.001). Our results demonstrate a prognostic role for both the R-IPI score and presence of high-risk pathologic features in DLBCL-type M-PTLD.

[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.

BCL2 and BCL6 atypical/unbalanced gene rearrangements in diffuse large B-cell lymphoma are indicators of an aggressive clinical course

AIMS

Diffuse large B-cell lymphoma (DLBCL) is the most common type of aggressive non-Hodgkin's lymphoma that represents a heterogeneous group of disease that is differentially characterised by clinical, molecular and cytogenetic features. MYC, BCL2 and BCL6 gene rearrangements have been identified as prognostic factors in DLBCL, especially for MYC. Nevertheless the frequency and effect of atypical/unbalanced BCL6, BCL2 and MYC translocations in DLBCL is not fully documented. Here, we aimed to analyse those atypical/unbalanced rearrangements in DLBCL and to assess their prognostic impact.

METHODS

We collected tumour tissue and clinical data from 97 DLBCL and used interphase fluorescence in situ hybridisation (FISH) with break-apart probe to characterise BCL6, BCL2 and MYC gene pattern.

RESULTS

19 of 97 (19,6%) cases of DLBCL had atypical/ unbalanced gene rearrangements (14 involving BCL6 gene, 5 involving BCL2 gene and none involving MYC gene). Compared with patients with simple gene rearrangement and patients without cytogenetic abnormality, patients with atypical/unbalanced gene rearrangement were in an unfavourable risk group by the International Prognostic Index (p=0039), died of disease (p=0012), harboured relapse or progression (p=0011) and had shorter overall (p=0,04), relapse free (p=0029) and event free (p=0026) survival.

CONCLUSIONS

We showed that patients with DLBCL with BCL2 or BCL6 atypical/unbalanced rearrangements constituted a group of patients with poor outcome. We also underlined the importance of FISH analyses, easily feasible in routine practise, at diagnosis of DLBCL to detect the rather frequent and clinically significant atypical/unbalanced aberrations of these genes.

Activation-induced cytidine deaminase overexpression in double-hit lymphoma: potential target for novel anticancer therapy

Activation-induced cytidine deaminase (AID) is one kind of the mutant enzymes, which target regulating the immunoglobulin (Ig) gene in Burkitt's lymphoma to initiate class switch recombination (CSR), resulting in c-Myc chromosomal translocation. However, it is not clear that whether AID induces c-Myc/IgH translocation in double-hit lymphoma (DHL) with c-Myc gene translocation. In this study, the AID in DHL tissues and classical diffuse large b-cell lymphoma (DLBCL) tissues were compared. The results suggested that AID is of important value in predicting DHL, stronger CSR of AID was observed in DHL patients, which exhibited AID overexpression and c-Myc gene translocation of DHL after CSR induction. It is concluded that AID directly induces CSR in DHL and may result in c-Myc gene translocation. Targeting AID may be a good treatment regimen for DHL.

Clinicopathological and genetic characteristics of diffuse large B-cell lymphoma of the oropharyngeal and maxillofacial region

OBJECTIVES

The study was aimed to analyze the clinicopathological and molecular pathological features of diffuse large B-cell lymphoma (DLBCL) in the oropharyngeal and maxillofacial region.

SUBJECTS AND METHODS

A retrospective review was performed with 36 patients who were diagnosed with primary DLBCL of the oropharyngeal and maxillofacial region from 2009 to 2017 in the Department of Pathology at the Hospital of Stomatology, Wuhan University. Immunohistochemistry and fluorescence in situ hybridization were performed.

RESULTS

Gene rearrangements of BCL2, BCL6, and MYC were observed in 5.6%, 33.3%, and 22.2%, respectively, including two double-hit and one triple-hit DLBCL (8.3%). There was a significant correlation between MYC protein expression and gene translocation (rs = 0.679, p < .001). However, 25% of cases with MYC rearrangement showed low MYC protein expression. In univariate analysis, MYC protein expression, BCL2 rearrangement, MYC rearrangement, and double/triple-hit DLBCL were associated with shorter overall survival, whereas only MYC protein expression was an independent prognostic value in multivariate model.

CONCLUSIONS

MYC protein expression was an essential prognostic marker of DLBCL in the oropharyngeal and maxillofacial region. Notably, immunohistochemical staining of MYC, BCL2, and BCL6 could not predict their gene rearrangements, although MYC protein expression was correlated with gene translocation.

An increase in MYC copy number has a progressive negative prognostic impact in patients with diffuse large B-cell and high-grade lymphoma, who may benefit from intensified treatment regimens

MYC translocations, a hallmark of Burkitt lymphoma, occur in 5-15% of diffuse large B-cell lymphoma, and have a negative prognostic impact. Numerical aberrations of MYC have also been detected in these patients, but their incidence and prognostic role are still controversial. We analyzed the clinical impact of MYC increased copy number on 385 patients with diffuse large B-cell lymphoma screened at diagnosis for MYC, BCL2, and BCL6 rearrangements. We enumerated the number of MYC copies, defining as amplified those cases with an uncountable number of extra-copies. The prevalence of MYC translocation, increased copy number and amplification was 8.8%, 15%, and 1%, respectively. Patients with 3 or 4 gene copies, accounting for more than 60% of patients with MYC copy number changes, had a more favorable outcome compared to patients with >4 copies or translocation of MYC, and were not influenced by the type of treatment received as first-line. Stratification according to the number of MYC extra-copies showed a negative correlation between an increasing number of copies and survival. Patients with >7 copies or the amplification of MYC had the poorest prognosis. Patients with >4 copies of MYC showed a similar, trending towards worse prognosis compared to patients with MYC translocation. The survival of patients with >4 copies, translocation or amplification of MYC seemed to be superior if intensive treatments were used. Our study underlines the importance of fluorescence in situ hybridization testing at diagnosis of diffuse large B-cell lymphoma to detect the rather frequent and clinically significant numerical aberrations of MYC.

Distinct genetic changes reveal evolutionary history and heterogeneous molecular grade of DLBCL with MYC/BCL2 double-hit

Using a Burkitt lymphoma-like gene expression signature, we recently defined a high-risk molecular high-grade (MHG) group mainly within germinal centre B-cell like diffuse large B-cell lymphomas (GCB-DLBCL), which was enriched for MYC/BCL2 double-hit (MYC/BCL2-DH). The genetic basis underlying MHG-DLBCL and their aggressive clinical behaviour remain unknown. We investigated 697 cases of DLBCL, particularly those with MYC/BCL2-DH (n = 62) by targeted sequencing and gene expression profiling. We showed that DLBCL with MYC/BCL2-DH, and those with BCL2 translocation, harbour the characteristic mutation signatures that are associated with follicular lymphoma and its high-grade transformation. We identified frequent MYC hotspot mutations that affect the phosphorylation site (T58) and its adjacent amino acids, which are important for MYC protein degradation. These MYC mutations were seen in a subset of cases with MYC translocation, but predominantly in those of MHG. The mutations were more frequent in double-hit lymphomas with IG as the MYC translocation partner, and were associated with higher MYC protein expression and poor patient survival. DLBCL with MYC/BCL2-DH and those with BCL2 translocation alone are most likely derived from follicular lymphoma or its precursor lesion, and acquisition of MYC pathogenic mutations may augment MYC function, resulting in aggressive clinical behaviour.

Perspectives on chemotherapy for the management of double-hit lymphoma

INTRODUCTION

. Unlike most B-cell lymphomas, they have poor response to standard R-CHOP therapy, tend to quickly develop resistance to cytotoxic chemotherapies, and are associated with higher central nervous system (CNS) infiltration. This can lead to increased risk of relapse and worse prognosis. DHL/THL represent a subset of lymphomas with unmet medical need.

AREA COVERED

The authors present the available data for the current treatment regimens including intensive chemotherapy regimens, hematopoietic stem-cell transplantation (HSCT), and CNS prophylaxis. They also discuss treatment for relapsed disease including targeted therapies.

EXPERT OPINION

There is currently no accepted standard of care for DHL/THL. For frontline therapy, we recommend enrollment in a well-designed clinical trial if possible, otherwise DA-EPOCH-R with CNS prophylaxis is a commonly used first-line therapy. The authors recommend close surveillance for patients achieving complete response, but for those who fail to achieve a complete response, then clinical trials, more aggressive salvage chemotherapy regimens, or cellular therapies are usually considered.

Emerging role of histone deacetylase inhibitors in the treatment of diffuse large B-cell lymphoma

Although current immunochemotherapy has increased the therapeutic efficacy in diffuse large B-cell lymphoma (DLBCL), there are still some patients who present unfavorable outcomes. Novel effective treatment strategies are needed to improve the prognosis of DLBCL. In this review, we discussed the functional mechanisms and therapeutic applications of histone deacetylases inhibitors (HDIs) in DLBCL from preclinical and clinical studies. The mechanistic rationale of HDIs involved a wide range of effects including the regulation of transcription factors, tumor suppressors, and cell surface molecules. Histone deacetylases inhibitors as monotherapy performed limited activity in the treatment of DLBCL in present clinical trials, but its combination with other regimens has emerged as potential treatment candidates with generally acceptable and manageable adverse effects. Further investigation on the anti-tumor mechanisms of HDIs and ongoing clinical trials will hopefully facilitate the application of HDIs in patients with DLBCL.

Novel insights into the pathogenesis of molecular subtypes of diffuse large B-cell lymphoma and their clinical implications

Introduction: Diffuse large B-cell lymphoma (DLBCL) represents a heterogeneous diagnostic category consisting of different molecular subtypes relying in their biology on distinct signaling pathways.Areas covered: This article provides an overview of the molecular understanding in DLBCL and highlights potential clinical implications reviewing relevant publications and clinical trials from PubMed and clinicaltrials.gov until August 2019.Expert opinion: Based on gene expression profiling, DLBCL can be divided in two broad subtypes, the activated B-cell-like (ABC) and germinal centre derived (GCB) DLBCL. Recent comprehensive genomic analyses revealed reproducible molecular clusters within the ABC/GCB classification and suggest a more profound molecular characterization to stratify patients within clinical trials. During the last couple of years, a multitude of novel targeted therapies has been developed, but so far without improving our current therapeutic standard of immunochemotherapy. Next to the limitation of toxic side effects and a more precise selection of patients, one of the greatest challenges will be to provide molecular characterization in a more time efficient way to enable a specific and individual treatment strategy.

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.

Clinical and genetic characterization of de novo double-hit B cell precursor leukemia/lymphoma

The 2016 revised World Health Organization (WHO) classification of lymphoid neoplasms included the category of high-grade B cell lymphomas (HGBLs) with combined MYC and BCL2 and/or BCL6 rearrangements (double-hit, DH). However, the clinical features of B cell precursor leukemia (BCP-ALL) that harbor DH genetics remain widely unknown. We performed a retrospective analysis of the German Multicenter Study Group for Adult ALL registry and a literature search for de novo DH-BCP-ALLs. We identified 6 patients in the GMALL registry and 11 patients published in the literature between 1983 and June 2018. Patients of all ages (range, 15-86 years) are affected. There is a high incidence of meningeal disease and other extramedullary disease manifestations. Current treatment approaches are mainly ALL-based and are sufficient to induce first complete remissions, but progression-free survival is only 4.0 months (95% CI, 1.5-6.5 months) and all patients succumb to their disease, once relapsed, with a median survival of 5.0 months (95% CI, 3.1-6.9 months), despite intensive salvage and targeted therapy approaches. Of all patients, only two that attained an initial complete remission were alive at data cutoff. In all cases, the BCL2 gene was rearranged to be in proximity to the IGH locus, whereas MYC had various translocation partners juxtaposed. There was no significant survival difference between IG and non-IG translocation partners (HR, 1.03; 95% CI, 0.33-3.2; p = 0.89). In conclusion, de novo DH-BCP-ALL is an aggressive B cell malignancy with deleterious outcome. Physicians have to be aware of this rare disease subset due to the atypical clinical behavior and especially because latest classification systems do not cover this sub-entity.

Mutation of TP53, translocation analysis and immunohistochemical expression of MYC, BCL-2 and BCL-6 in patients with DLBCL treated with R-CHOP

Diffuse large B-cell lymphoma (DLBCL) is an aggressive lymphoma with diverse outcomes. Concurrent translocation of MYC and BCL-2 and/or BCL-6, and concurrent immunohistochemical (IHC) high expression of MYC and BCL-2, have been linked to unfavorable treatment responses. TP53-mutated DLBCL has also been linked to worse outcome. Our aim was to evaluate the aforementioned issues in a cohort of 155 patients uniformly treated with R-CHOP-like therapies. We performed direct sequencing of TP53 exons 5, 6, 7 and 8 as well as fluorescence in-situ hybridization (FISH) of MYC, BCL-2 and BCL-6, and IHC of MYC, BCL-2 and BCL-6. In multivariate analysis, TP53 mutations in L3 and loop-sheet helix (LSH) associated with a risk ratio (RR) of disease-specific survival (DSS) of 8.779 (p = 0.022) and a RR of disease-free survival (DFS) of 10.498 (p = 0.011). In IHC analysis BCL-2 overexpression was associated with inferior DFS (p = 0.002) and DSS (p = 0.002). DLBCL with BCL-2 and MYC overexpression conferred inferior survival in all patients (DSS, p = 0.038 and DFS, p = 0.011) and in patients with non-GC phenotype (DSS (p = 0.013) and DFS (p = 0.010). Our results imply that in DLBCL, the location of TP53 mutations and IHC analysis of BCL-2 and MYC might have a role in the assessment of prognosis.

Dissecting aggressive B-cell lymphoma through genomic analysis - What is clinically relevant?

The aggressive B-cell lymphomas are a diverse collection of cancers grouped together based on clinical behavior and derivation from B lymphocytes. Genomic analyses on these tumours are now translating into improved classification systems and identification of underpinning targetable biology. Simple karyotyping revealed key translocations involving MYC, BCL2, and BCL6 that have impacted lymphoma classification in the World Health Organization classification scheme. Subsequently, gene expression profiling identified molecular subgroups within the most common lymphoma, diffuse large B-cell lymphoma (DLBCL): activated B-cell-like and germinal centre B-cell-like. Finally, next generation sequencing has revealed a modest number of frequently mutated genes and a long list of infrequent mutations. The mutational landscapes involve diverse genes associated with dysregulated signalling, epigenetic modification, blockade of cellular differentiation, and immune evasion. These mutational "signatures" are enriched in the different aggressive lymphoma subtypes impacting phenotypes and identifying therapeutic targets. Challenges to implementing genomic assays into clinical practice remain.

Advances in pathological understanding of high-grade B cell lymphomas

INTRODUCTION

The designation high-grade B-cell lymphoma (HGBL) has been incorporated into the 2016 Revision of the WHO classification of lymphoid neoplasms and includes two types: (1) HGBL, not otherwise specified; and (2) HGBL with MYC and BCL2 and/or BCL6 rearrangements, also known as double or triple hit lymphoma (DHL/THL). These categories of lymphomas represent 1-2% of non-Hodgkin lymphomas and a considerable portion of DLBCL patients who are primary refractory to R-CHOP therapy. It corresponds to the designation 'B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt lymphoma' in the 2008 WHO classification. Areas covered: This paper provides an update of HGBL, focusing on their pathologic features, prognosis, and diagnostic workup. It highlights advances in our understanding of DHL/THL. Expert commentary: The diagnosis relies on FISH testing and the major controversial question is when to perform it to diagnose virtually all DHL/THL cases, but also being cost effective. Currently there is no consensus. Considering the high refractory rate of these patients to standard R-CHOP induction, the authors recommend FISH testing in all newly diagnosed large B-cell lymphoma by using our stepwise test strategy. With the progress of molecular genetics, the prognosis will be further stratified and HGBL-NOS maybe further evolve too.

Inferior survival in high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements is not associated with MYC/IG gene rearrangements

High-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements (double-/triple-hit lymphoma) have an aggressive clinical course. We investigated the prognostic value of transformation from low-grade lymphoma, cytological features (high grade versus large cell), MYC rearrangement partners (immunoglobulin versus nonimmunoglobulin gene), and treatment. We evaluated 100 adults with double-/triple-hit lymphoma, reviewing cytological features; cell of origin; and rearrangements of MYC, BCL2, and BCL6 using MYC, BCL2, and BCL6 break-apart and IGH/MYC, IGL/MYC, IGK/MYC, and IGH/BCL2 dual-fusion interphase fluorescence in situ hybridization probes. Outcome analysis was restricted to patients with lymphoma, de novo or at transformation, who received anthracycline-based chemotherapy. Among them, 60% had high-grade cytological features; 91% had a germinal center B-cell phenotype, and 60% had a MYC/IG rearrangement. Germinal center B-cell phenotype was associated with BCL2 rearrangements (P<0.001). Mean (95% confidence interval) 5-year overall survival was 49% (37%–64%). Transformation from previously treated and untreated low-grade lymphoma was associated with inferior overall survival (hazard ratio, 2.99; P=0.008). Patients with high-grade cytological features showed a non-significant tendency to inferior outcome (hazard ratio, 2.32; P=0.09). No association was observed between MYC rearrangement partner and overall survival (hazard ratio, 1.00; P=0.99). Compared with patients receiving rituximab, cyclophosphamide, doxorubicin, and vincristine (R-CHOP) and dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab (EPOCH-R), patients receiving rituximab, cyclophosphamide, vincristine, doxorubicin, methotrexate/ifosfamide, etoposide, and cytarabine (R-CODOX-M/IVAC) had a non-significant tendency to better overall survival (hazard ratio, 0.37; P=0.10). In conclusion, high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements had heterogeneous outcomes and MYC/IG rearrangements were not associated with inferior overall survival.

High-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements with diffuse large B-cell lymphoma morphology

High-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements (HGBL-DH/TH) is a newly defined entity in the latest World Health Organization Classification. Accurate diagnosis would appear to mandate fluorescence in situ hybridization (FISH) for all tumors with diffuse large B-cell lymphoma (DLBCL) morphology. We present the results of FISH, cell-of-origin, and immunohistochemistry (IHC) testing from 1228 DLBCL biopsies from 3 clinical trials and a population-based registry. HGBL-DH/TH made up 7.9% of the DLBCL, confined primarily to the germinal center B-cell-like (GCB; 13.3%) compared with activated B-cell-like (ABC; 1.7%) subtype (P < .001). HGBL-DH/TH with BCL2 rearrangement is a GCB phenomenon with no cases observed in 415 ABC DLBCL. A screening strategy restricting FISH testing to tumors of GCB subtype (by Lymph2Cx or Hans IHC) plus dual protein expression of MYC and BCL2 by IHC could limit testing to 11% to 14% of tumors, with a positive predictive value of 30% to 37%; however, this strategy would miss approximately one-quarter of tumors with HBGL-DH/TH with BCL2 rearrangement and one-third of all HGBL-DH/TH. These results provide accurate estimation of the proportion of HGBL-DH/TH among tumors with DLBCL morphology and allow determination of the impact of various methods available to screen DLBCL tumors for FISH testing.