High-grade B-cell lymphoma: a term re-purposed in the revised WHO classification

The fifth edition of the WHO classification of mature B-cell neoplasms: open questions for research

The fifth edition of the World Health Organization Classification of Haematolymphoid Tumours (WHO-HAEM5) is the product of an evidence-based evolution of the revised fourth edition with wide multidisciplinary consultation. Nonetheless, while every classification incorporates scientific advances and aims to improve upon the prior version, medical knowledge remains incomplete and individual neoplasms may not be easily subclassified in a given scheme. Thus, optimal classification requires ongoing study, and there are certain aspects of some entities and subtypes that require further refinements. In this review, we highlight a selection of these challenging areas to prompt more research investigations. These include (1) a 'placeholder term' of splenic B-cell lymphoma/leukaemia with prominent nucleoli (SBLPN) to accommodate many of the splenic lymphomas previously classified as hairy cell leukaemia variant and B-prolymphocytic leukaemia, a clear new start to define their pathobiology; (2) how best to classify BCL2 rearrangement negative follicular lymphoma including those with BCL6 rearrangement, integrating the emerging new knowledge on various germinal centre B-cell subsets; (3) what is the spectrum of non-IG gene partners of MYC translocation in diffuse large B-cell lymphoma/high-grade B-cell lymphoma and how they impact MYC expression and clinical outcome; how best to investigate this in a routine clinical setting; and (4) how best to define high-grade B-cell lymphoma not otherwise specified and high-grade B-cell lymphoma with 11q aberrations to distinguish them from their mimics and characterise their molecular pathogenetic mechanism. Addressing these questions would provide more robust evidence to better define these entities/subtypes, improve their diagnosis and/or prognostic stratification, leading to better patient care. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

EFNB1 levels determine distinct drug response patterns guiding precision therapy for B-cell neoplasms

The multi-omics data has greatly improved the molecular diagnosis of B-cell neoplasms, but there is still a lack of predictive biomarkers to guide precision therapy. Here, we analyzed publicly available data and found that B-cell neoplasm cell lines with different levels of EFNB1 had distinctive drug response patterns of inhibitors targeting SRC/PI3K/AKT. Overexpression of EFNB1 promoted phosphorylation of key proteins in drug response, such as SRC and STMN1, conferring sensitivity to SRC inhibitor and cytotoxic drugs. EFNB1 phosphorylation signaling network was significantly associated with the prognosis of GCB-DLBCL patients. Moreover, EFNB1 levels were correlated with cell of origin (COO) scores, suggesting that EFNB1 is a quantitative indicator of cell differentiation. Ultimately, we proposed a model for the stratification of human B-cell malignancies and the implementation of targeted therapies based on EFNB1 levels. Our findings highlight that EFNB1 level is a promising biomarker for predicting drug response, COO and prognosis.

Aggressive non-Hodgkin lymphoma in the pediatric and young adult population; diagnostic and molecular pearls of wisdom

Mature non-Hodgkin lymphomas (NHLs) of the pediatric and young adults(PYA), including Burkitt lymphoma (BL), diffuse large B cell lymphoma (DLBCL), high-grade B cell lymphoma (HGBCL), primary mediastinal large B cell lymphoma (PMBL) and anaplastic large cell lymphoma (ALCL), generally have excellent prognosis compared to the adult population. BL, DLBCL and HGBCL are usually of germinal center (GCB) origin in the PYA population. PMBL neither belongs to the GCB nor the activated B cell subtype and is associated with a poorer outcome than BL or DLBCL of comparable stage. Anaplastic large cell lymphoma is the most frequent peripheral T cell lymphoma occurring in the PYA and accounts for 10-15% of childhood NHL. Most pediatric ALCL, unlike in the adult, demonstrate expression of anaplastic lymphoma kinase (ALK). In recent years, the understanding of the biology and molecular features of these aggressive lymphomas has increased tremendously. This has led to reclassification of newer PYA entities including Burkitt-like lymphoma with 11q aberration. In this review, we will discuss the current progress discovered in frequently encountered aggressive NHLs in the PYA, highlighting the clinical, pathologic and molecular features that aid in the diagnosis of these aggressive lymphomas. We will be updating the new concepts and terminologies used in the new classification systems.

The synergy of the XPO1 inhibitors combined with the BET inhibitor INCB057643 in high-grade B-cell lymphoma via downregulation of MYC expression

High grade B-cell lymphoma with MYC and BCL2 rearrangements (HGBCL-DH) represents an uncommon B-cell lymphoma (BCL) with aggressive clinical courses and poor prognosis. Despite revolutionary therapeutic advances in BCL, there has been limited treatment progress in HGBCL-DH, thus necessitating additional therapeutic strategies for HGBCL-DH. This study demonstrated that the BET antagonist INCB057643 synergized with the XPO1 inhibitors (selinexor and eltanexor) to decrease cell viability and increase cell apoptosis in HGBCL-DH cells with or without TP53 mutations. As anticipated, the combined treatment of INCB057643 with selinexor slowed tumor growth and reduced the tumor burden in TP53-mutated HGBCL-DH xenografts. Mechanistically, MYC functional inhibition was a potential molecular mechanism underlying the synergy of the combined INCB057643 and selinexor treatment in HGBCL-DH cells independent of TP53 mutation status. In TP53 mutated HGBCL-DH cells, inducing DNA damage and impairing the DNA damage response (DDR) were involved in the therapeutic interaction of the combined regimen. In TP53 wild-type cells, the molecular mechanism was linked with upregulation of p53 levels and activation of its targeted pathways, rather than dysregulation of the DDR. Collectively, we might provide a potential promising combination therapy regimen for the management of HGBCL-DH. Clinical evaluations are warranted to confirm this conclusion.

Advances in Polatuzumab Vedotin-PIIQ Therapy: A Review of Treatment Efficacy in Diffuse Large B Cell Lymphoma and High-Grade B Cell Lymphoma

Polatuzumab vedotin (PV) is an antibody-drug conjugate that has shown promising results in the treatment of diffuse B-cell lymphoma (DLBCL) and high-grade B-cell lymphoma (HGBCL). This abstract summarizes the current understanding of PV's use in these malignancies based on available clinical data. Multiple clinical trials have evaluated PV as a part of combination therapy regimens in relapsed/refractory DLBCL and HGBCL. The pivotal Phase II study, GO29365, demonstrated that PV in combination with bendamustine and rituximab (BR) significantly improved progression-free survival and overall survival compared to BR alone in patients with relapsed/refractory DLBCL who ineligible for stem cell transplantation were. Subsequently, the US Food and Drug Administration granted accelerated approval to PV in this setting. PV's mechanism of action involves targeting CD79b, a cell surface receptor expressed in B-cell malignancies, and delivering the cytotoxic agent monomethyl auristatin E to CD79b-expressing cells. This approach enhances the selective killing of cancer cells while sparing normal cells. The safety profile of PV is generally manageable, with adverse events including infusion-related reactions, cytopenia, peripheral neuropathy, and infections. Overall, PV has emerged as a valuable treatment option for patients with relapsed/refractory DLBCL and HGBCL, offering improved outcomes when combined with appropriate chemotherapy regimens. Ongoing research and clinical trials are further exploring PV's potential in various treatment settings, including frontline therapy and in combination with other novel agents.

Establishment of a primary renal lymphoma model and its clinical relevance

Extranodal dissemination is an important feature of aggressive B-cell lymphoma. Owing to the lack of available animal models, the study on extranodal dissemination of lymphoma is greatly limited. Here, we identified a novel cell line, named MA-K, which originated from the Eμ-Myc;Cdkn2a-/- cell line, named MA-LN in this study. Compared to MA-LN, MA-K tended to disseminate in the kidney rather than the lymph nodes in the lymphoma transplantation model, resembling human primary renal lymphoma. The transcriptome analysis revealed that MA-K had undergone transcriptional evolution during the culture. The specialized transcriptional pattern analysis we proposed in this study identified that the FOXO1-BTG1-MYD88 pattern was formed in MA-K. Further analysis found that the translation pathway was the most enriched pathway in specially expressed genes (SEGs) in MA-K. Among the SEGs, three upregulated genes, RPLP2, RPS16, and MRPS16, and five downregulated genes, SSPN, CD52, ANKRD37, CCDC82, and VPREB3, in MA-K were identified as promising biomarkers to predict the clinical outcomes of human DLBCL. Moreover, the joint expression of the five-gene signature could effectively predict clinical outcomes of human DLBCL in three groups. These findings suggested that the MA-K cell line had strong clinical relevance with human aggressive B-cell lymphoma. Moreover, the MA-K primary renal lymphoma model, as a novel syngenetic mouse model, will be greatly useful for both basic research on lymphoma dissemination and preclinical efficacy evaluation of chemotherapy and immunotherapy.

Double-hit and double-expressor primary central nervous system lymphoma: Experience from North India of an infrequent but aggressive variant

Background

High-grade non-Hodgkin B-cell lymphoma is an aggressive mature B-cell lymphoma that depicts poor treatment response and worse prognosis. The presence of MYC and B-cell lymphoma 2 (BCL2) and/or B-cell lymphoma 6 (BCL6) rearrangements qualifies for triple-hit and double-hit lymphomas (THL/DHL), respectively. We attempted to explore the incidence, distribution, and clinical characteristics of the primary high-grade B-cell lymphoma of the central nervous system (CNS) in our cohort from North India.

Methods

All the histologically confirmed cases of primary CNS diffuse large B-cell lymphoma (PCNS-DLBCL) over a period of 8 years were included. Cases showing MYC and BCL2 and/or BCL6 expression on immunohistochemistry (IHC) (double- or triple-expressor) were further analyzed by fluorescence in situ hybridization for MYC, BCL2 and /or BCL6 rearrangements. The results were correlated with other clinical and pathological parameters, and outcome.

Results

Of total 117 cases of PCNS-DLBCL, there were seven (5.9%) cases of double/triple-expressor lymphomas (DEL/TEL) (six double- and one triple-expressor) with median age of 51 years (age range: 31-77 years) and slight female predilection. All were located supratentorially and were of non-geminal center B-cell phenotype. Only triple-expressor case (MYC+/BCL2+/BCL6+) demonstrated concurrent rearrangements for MYC and BCL6 genes indicating DHL (n = 1, 0.85%), while none of the double-expressors (n = 6) showed MYC, BCL2, or BCL6 rearrangements. The mean overall survival of the DEL/TEL was 48.2 days.

Conclusion

DEL/TEL and DHL are uncommon in CNS; mostly located supratentorially and are associated with poor outcome. MYC, BCL2, and BCL6 IHC can be used as an effective screening strategy for ruling out double/ triple-expressor PCNS-DLBCLs.

A multi-center analysis of the impact of DA-EPOCH-R dose-adjustment on clinical outcomes of patients with double/triple-hit lymphoma

Patients with double- and triple-hit lymphomas (DHL/THL) have inferior outcomes with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), and higher-intensity regimens such as dose-adjusted (DA)-EPOCH-R are standard. Dose-intensification of DA-EPOCH-R is guided by hematologic toxicity, without conclusive benefit for DHL/THL patients. To determine if cumulative doses of DA-EPOCH-R or compliance with dose adjustment impacts survival, we retrospectively evaluated detailed clinical data from 109 adult (age ≥18 years) patients with DHL/THL treated with ≥4 cycles of induction DA-EPOCH-R from 2014 to 2019 at six centers. A comprehensive multivariate analysis was performed. Survival outcomes for the entire cohort were comparable to historical estimates for DHL/THL treated with this regimen (median follow-up 27.9 months). Overall survival (OS) and progression-free survival (PFS) were not significantly associated with cumulative chemotherapy dose, dose escalation, or compliance with dose adjustment. Heterogeneous dosing practices were observed. Prospective investigation is warranted to evaluate the practice of dose adjustment of R-EPOCH for patients with DHL/THL.

High-intensity chemotherapy improved the prognosis of patients with high-grade B-cell lymphoma

Objective

High-grade B-cell lymphoma (HGBL) is highly aggressive and has a poor prognosis.

Methods

The clinical data of 76 patients with High-grade B-cell lymphoma treated in our lymphoma center from July 2016 to April 2020 were analyzed retrospectively. The clinical features, treatment and prognosis of patients with two types of high-grade B-cell lymphoma were compared and analyzed.

Results

Among 76 patients with high-grade B-cell lymphoma, 44 cases (57.9%) were high-grade B-cell lymphoma, accompanied by MYC and Bcl-2 and/or Bcl-6 rearrangement (HGBLR) patients, and 32 cases (42.1%) were HGBL, NOS patients. The bone marrow infiltration, IPI (international prognostic index), Ann Arbor stage (III/IV), extranodal disease are more likely to occur in HGBLR group (P <0.05). Survival analysis of patients showed that overall survival (OS) and progression free survival (PFS) in HGBLR group were significantly shorter than those in HGBL, NOS group (median OS: 21 months vs not reached, P=0. 022; median PFS: 5 months vs 12 months, P = 0. 001). Further analysis demonstrated that, as compared with R-CHOP regimen, patients with HGBL who received high-intensity chemotherapy regimens (DA-EPOCH-R, R-CODOX-M/IVAC and R-Hyper-CVAD) had longer OS (median OS, 16 months vs not reached, P=0. 007) and PFS (median PFS, 5 months vs 11 months, P<0.001). Moreover, mu1tivariate ana1ysis showed that high-intensity chemotherapy regimens were independent risk factors for both PFS (P =0.001, HR: 0.306, 95% CI: 0.153-0.610) and OS (P =0.004, HR: 0.262, 95% CI: 0.105-0.656) in patients with HGBL.

Conclusions

HGBLR patients have worse prognosis than patients with HGBL, NOS. High-intensity chemotherapy may improve the prognosis of patients with HGBL.

Burkitt lymphoma

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

CAR T-cell Therapy in Highly-Aggressive B-Cell Lymphoma: Emerging Biological and Clinical Insights

Recently, significant progress has been made in identifying novel therapies, beyond conventional immunochemotherapy strategies, with efficacy in B-cell lymphomas. One such approach involves targeting the CD19 antigen on B-cells with autologous-derived chimeric antigen receptor (CAR) cells. This strategy is highly effective in patients with relapsed and refractory diffuse large B-cell lymphoma (DLBCL) as evidenced by recent regulatory approvals. Recent reports suggest that this is an effective strategy for high-grade B-cell. The biological underpinnings of these entities and how they overlap with each other and DLBCL continue to be areas of intense investigation. Therefore, as more experience with CAR T-cell approaches is examined, it is interesting to consider how both tumor-cell specific and microenvironment factors that define these highly aggressive subsets influence susceptibility to this approach.

Blastoid high-grade B-cell lymphoma initially presenting in bone marrow: a diagnostic challenge

The 2016 WHO classification introduced the category of high-grade B-cell lymphoma (HGBL), which includes one poorly understood subset, blastoid-HGBL. Establishing the diagnosis and distinguishing blastoid-HGBL from B-acute lymphoblastic leukemia (B-ALL) in bone marrow can be challenging. We assessed 31 cases of blastoid-HGBL diagnosed initially in bone marrow and compared this group to 36 cases of B-ALL using immunophenotyping, fluorescence in situ hybridization, and targeted next generation sequencing analysis. The 31 blastoid-HGBL cases included 14 HGBL with MYC and BCL2 and/or BCL6 rearrangements (double hit lymphoma, DHL), 13 HGBL, not otherwise specified (NOS), and four cases with TdT expression that were difficult to classify. Compared with B-ALL, blastoid-HGBL cases more often showed increased intensity/bright expression of CD20, CD38, CD45, BCL-6, and MYC, and less frequent bright expression of CD10 and TdT. Cases of blastoid-HGBL also more frequently had MYC rearrangement, a complex karyotype and TP53 mutation (p < 0.01). With the exception of CD34, no other single factor, including TdT, was sensitive or adequately specific to distinguish blastoid-HGBL from B-ALL. We developed a scoring system using six distinctive features between 16 cases of unequivocal blastoid HGBL and 22 cases of CD34-positive B-ALL, with a score of ≥3 defining blastoid-HGBL. The system was further validated by using 15 cases of surface light chain negative, and/or CD45 dim to negative blastoid-HGBL and 14 cases of CD34-negative B-ALL. The sensitivity, specificity, positive, and negative predictive value of this scoring system were 100%, 94%, 94%, and 100%, respectively. Using this system, the four cases with TdT expression were all classified as blastoid-HGBL: three were DHL and one was HGBL-NOS. In conclusion, blastoid-HGBL shows distinctive immunophenotypic, cytogenetic, and molecular features as compared with B-ALL. The proposed scoring system can be helpful for the classification of diagnostically challenging blastoid lymphoid tumors presenting initially in the bone marrow.

Prognostic Value of Radiomic Features of 18F-FDG PET/CT in Patients With B-Cell Lymphoma Treated With CD19/CD22 Dual-Targeted Chimeric Antigen Receptor T Cells

Objective

In the present study, we aimed to evaluate the prognostic value of PET/CT-derived radiomic features for patients with B-cell lymphoma (BCL), who were treated with CD19/CD22 dual-targeted chimeric antigen receptor (CAR) T cells. Moreover, we explored the relationship between baseline radiomic features and the occurrence probability of cytokine release syndrome (CRS).

Methods

A total of 24 BCL patients who received 18F-FDG PET/CT before CAR T-cell infusion were enrolled in the present study. Radiomic features from PET and CT images were extracted using LIFEx software, and the least absolute shrinkage and selection operator (LASSO) regression was used to select the most useful predictive features of progression-free survival (PFS) and overall survival (OS). Receiver operating characteristic curves, Cox proportional hazards model, and Kaplan-Meier curves were conducted to assess the potential prognostic value.

Results

Contrast extracted from neighbourhood grey-level different matrix (NGLDM) was an independent predictor of PFS (HR = 15.16, p = 0.023). MYC and BCL2 double-expressor (DE) was of prognostic significance for PFS (HR = 7.02, p = 0.047) and OS (HR = 10.37, p = 0.041). The combination of NGLDM_ContrastPET and DE yielded three risk groups with zero (n = 7), one (n = 11), or two (n = 6) factors (p &lt; 0.0001 and p = 0.0004, for PFS and OS), respectively. The PFS was 85.7%, 63.6%, and 0%, respectively, and the OS was 100%, 90.9%, and 16.7%, respectively. Moreover, there was no significant association between PET/CT variables and CRS.

Conclusions

In conclusion, radiomic features extracted from baseline 18F-FDG PET/CT images in combination with genomic factors could predict the survival outcomes of BCL patients receiving CAR T-cell therapy.

Therapeutic Outcomes in High-Grade B-Cell Lymphoma, NOS: Retrospective Analysis

The nomenclature high-grade non-Hodgkin's lymphoma was repurposed in the World Health Organization (WHO) 2016 update as high-grade B cell lymphoma (HGBL). However, among the HGBL entities HGBL, not otherwise specified (NOS) remains a poorly described entity with a lack of literature regarding its treatment and prognosis.

The baseline characteristics, treatment, and outcome of HGBL, NOS cases were analyzed. Thirty HGBL, NOS patients were diagnosed between January 2017 and December 2019. Their median age was 49.3 years, and 30% had advanced IPI. The majority received R-CHOP chemotherapy, while five patients received dose-adjusted R-EPOCH. At a median follow-up of 15 months, nine patients had disease progression or relapse. EFS and OS were 22 months (12.1–31.9 months) and 37 months (29.4–44.0 months) respectively. Only NCCN-IPI ≤ 2 showed significant influence on the outcome. The results were similar to the outcomes previously reported.

This study highlights the importance of NCCN-IPI in ascertaining the prognosis of HGBL, NOS. The literature review suggests that more intensive chemotherapy is ideal for HGBL, NOS. However, prospective trials are needed to prove whether the treatment of HGBL, NOS can be tailored based on NCCN-IPI.

Defining and Treating High-grade B-cell lymphoma, NOS

High-grade B-cell lymphoma, not otherwise specified (HGBL, NOS) is a recently introduced diagnostic category for aggressive B-cell lymphomas. It includes tumors with Burkitt-like or blastoid morphology that do not have double-hit cytogenetics and that cannot be classified as other well-defined lymphoma subtypes. HBCL, NOS are rare and heterogeneous; most have germinal center B-cell phenotype, and up to 45% carry a single-hit MYC rearrangement, but otherwise they have no unifying immunophenotypic or cytogenetic characteristics. Recent analyses utilizing gene expression profiling (GEP) revealed that up to 15% of tumors currently classified as diffuse large B-cell lymphoma display a HGBL-like GEP signature, indicating a potential to significantly expand the HGBL category using more objective molecular criteria. Optimal treatment of HGBL, NOS is poorly defined due to its rarity and inconsistent diagnostic patterns. A minority of patients have early-stage disease which can be managed with standard RCHOP-based approaches with or without radiation. For advanced-stage HGBL, NOS, which often presents with aggressive, disseminated disease, high lactate dehydrogenase, and involvement of extranodal organs (including the central nervous system [CNS]), intensified Burkitt lymphoma-like regimens with CNS prophylaxis may be appropriate. However, many patients diagnosed at age > 60 years are not eligible for intensive immunochemotherapy. An improved, GEP and/or genomic-based pathologic classification that could facilitate HGBL-specific trials is needed to improve outcomes for all patients. In this review, we discuss the current clinicopathologic concept of HGBL, NOS, existing data on its prognosis and treatment, and delineate potential future taxonomy enrichments based on emerging molecular diagnostics.

Transformation of low-grade follicular lymphoma with partial marginal zone differentiation: Two cases

Two cases of low-grade follicular lymphoma, with marginal zone differentiation and/or with high proliferation rate in one of them, are reported with transformation into high grade B-cell and B-lymphoblastic lymphomas. The contribution of these features to the transforming process, although previously described, is infrequent, and has not been deciphered to date.

Screening Strategy for Detecting Double-Hit Lymphoma in a Resource-Limited Setting

AIM

High-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements [double-hit lymphomas (DHL)] are aggressive lymphomas. Current literature recommends fluorescent in-situ hybridization analysis (FISH) in all cases of diffuse large B-cell lymphoma (DLBCL) to identify cases of DHL. However, this approach is not feasible in a resource-limited setting. We analyzed cases of de novo high-grade B-cell non-Hodgkin lymphoma using histomorphology, immunohistochemistry and FISH to identify which cases need to undergo FISH testing in a resource-limited setting.

MATERIALS AND METHODS

Cases of de novo high-grade B-cell non-Hodgkin lymphoma that included DLBCL, not otherwise specified and B-cell lymphoma unclassifiable (BCLU) with features intermediate between DLBCL and Burkitt lymphoma diagnosed over a period of 5 years were analyzed by Hans algorithm, MYC, BCL2, and Ki67. MYC, BCL2, and BCL6 break apart FISH was tested in selected cases.

RESULTS

One hundred and nine cases were obtained, of which 102 had DLBCL morphology and 7 had BCLU/blastoid morphology. BCL2 expression was noted in 48 cases (44%), MYC in 33 cases (30.3%) and MYC/BCL2 co-expression in 24 cases (22%). FISH testing could be done in 42 consecutive cases, of which 5 cases had MYC and BCL2 co-rearrangement (11.9%) (double-hit) and 2 cases showed rearrangement for only MYC (4.7%) (single-hit). Single-hit lymphoma/DHL showed significant independent positive correlation with BCLU/blastoid morphology, CD10 expression, germinal center B-cell phenotype, and MYC/BCL2 co-expression. The sensitivity and specificity of each parameters include BCLU/blastoid morphology (42% vs. 94%), CD10 positive (50% vs. 88%), germinal center B-cell phenotype (57% vs. 82%), MYC/BCL2 co-expression (85% vs. 80%). Selected candidates for FISH (any one of the above parameters) using this strategy showed a sensitivity and specificity of 100% and 68%, respectively (P=0.001).

CONCLUSION

We propose a highly sensitive screening strategy for detection of MYC/BCL2 rearrangement in high-grade B-cell lymphoma in a resource-limited setting (pending validation in a larger cohort).

Molecular Update and Evolving Classification of Large B-Cell Lymphoma

Simple Summary

The development of high-throughput technologies in recent years has increased our understanding of the molecular complexity of lymphomas, providing new insights into the pathogenesis of large B-cell neoplasms and identifying different molecular biomarkers with prognostic impact, that lead to the revision of the World Health Organization consensus classification of lymphomas. This review addresses the main histopathological and molecular features of large B-cells lymphomas, providing an overview of the main recent novelties introduced by the last update of the consensus classification.

Abstract

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.

De novo double-hit B-cell precursor leukemia/lymphoma - an unusual presentation as peritoneal lymphomatosis

Peritoneal lymphomatosis (PL) is a rare presentation of extranodal precursor leukemia/lymphoma. The presentation is often non-specific, leading to delayed diagnosis and treatment. In this case, though the preliminary diagnosis was established on ascitic fluid cytology, the disease progressed rapidly, leading to demise before initiating chemotherapy. Immunophenotyping and molecular studies, performed later, established a diagnosis of de novo B-cell precursor leukemia/lymphoma with MYC, BCL2 rearrangements (Double-hit lymphoma). MYC, BCL2 rearrangements are rarely reported in precursor B-lymphoma/leukemia which carry dismal prognosis. In this report, we illustrate autopsy findings of PL in an elderly gentleman who presented with ascites for evaluation.

High performance of multiplex fluorescence in situ hybridization to simultaneous detection of BCL2 and BCL6 rearrangements: useful application in the characterization of DLBCLs

Chromosomal rearrangements involving BCL2, BCL6 and MYC are commonly found in the most frequent B cell lymphomas, namely follicular lymphomas (FLs) and diffuse large B-cell lymphomas (DLBCLs). Particularly, BCL2-rearrangement represents a diagnostic hallmark in FLs, whereas MYC translocation can occur simultaneously with BCL2 and/or BCL6 rearrangements, defining a specific category of DLBCLs with a poorer prognosis. In this study, we aim to validate the diagnostic performance of multiplex BCL2/BCL6 FISH approach in formalin-fixed paraffin-embedded FLs and DBCLs and cytological samples of DLBCL comparing to the classic set of single break-apart probes. We collected a series of lymphomas, including 85 DLBCLs, 45 FLs and 36 other B-cell lymphoma histotypes and 16 cytological samples of DLBCLs. MYC, BCL2 and BCL6 rearrangements were previously assessed by a classic FISH test using single break-apart probes. All samples were analysed by a multiplex FISH assay. In the FL series, 38 cases showed BCL2-R; in the DLBCLs series, MYC-R was detected in 21 out of 85 DLBCL patients, BCL2-R in 10 out of 85 and BCL6-R in 33 out of 85. In the DLBCL cytological series, MYC-R was detected in 4 out of 16, BCL2-R in 4 out of 16 and BCL6-R in 1 out of 16. Notably, in FFPE, 13 double-hit lymphomas (DHLs) and 3 triple-hit lymphomas (THLs) were detected; in the cytological series, only 3 DHL cases were observed. The dual BCL2/BCL6 FISH probe test results were fully concordant with the results obtained using classic BCL2 and BCL6 single break apart. Particularly, multiplex FISH to simultaneously detect BCL2-R and BCL6-R on a single slide could find a wide application in the characterisation of double- and triple-hit DLBCLs.

Flow cytometry in the diagnosis of mature B-cell lymphoproliferative disorders

B-lineage lymphoproliferative disorders (LPD) are rather frequent diseases, associated with specific clinical or biological features but also sometimes of fortuitous discovery. Multiparameter flow cytometry plays a major role for a rapid diagnostic indication, on peripheral blood or bone marrow samples in most instances, guiding complementary analyses and allowing for the proper therapeutic management of patients. After describing the important pre-analytical precautions required for an adequate assessment, the immunophenotypic features of small-cell and large-cell lymphomas are described in this review. The ubiquitous expression of CD19 is a first mandatory gating step. A possible clonal proliferation is then suspected by the demonstration of surface immunoglobulin light chain restriction. The aberrant presence of CD5 allows to segregate chronic lymphocytic leukemia and mantle cell lymphoma in most cases. Other LPD exhibit specific immunophenotypic features. A table of useful markers and a decision tree are provided. Of note, immunophenotypic data should as much as possible be interpreted in an integrated manner, involving the patient's clinical and other biological features, and be completed by further chromosomal and/or molecular investigations.

Aggressive B-cell Lymphoma with MYC/TP53 Dual Alterations Displays Distinct Clinicopathobiological Features and Response to Novel Targeted Agents

Diffuse large B-cell lymphoma (DLBCL) is the major type of aggressive B-cell lymphoma. High-grade B-cell lymphoma (HGBCL) with MYC/BCL2 double-hit (DH) represents a distinct entity with dismal prognosis after standard immunochemotherapy in the current WHO lymphoma classification. However, whether TP53 mutation synergizes with MYC abnormalities (MYC rearrangement and/or Myc protein overexpression) contributing to HGBCL-like biology and prognosis is not well investigated. In this study, patients with DLBCL with MYC/TP53 abnormalities demonstrated poor clinical outcome, high-grade morphology, and distinct gene expression signatures. To identify more effective therapies for this distinctive DLBCL subset, novel MYC/TP53/BCL-2-targeted agents were investigated in DLBCL cells with MYC/TP53 dual alterations or HGBCL-MYC/BCL2-DH. A BET inhibitor INCB057643 effectively inhibited cell viability and induced apoptosis in DLBCL/HGBCL cells regardless of MYC/BCL2/TP53 status. Combining INCB057643 with a MDM2-p53 inhibitor DS3032b significantly enhanced the cytotoxic effects in HGBCL-DH without TP53 mutation, while combining with the BCL-2 inhibitor venetoclax displayed potent therapeutic synergy in DLBCL/HGBCL cells with and without concurrent TP53 mutation. Reverse-phase protein arrays revealed the synergistic molecular actions by INCB057643, DS3032b and venetoclax to induce cell-cycle arrest and apoptosis and to inhibit AKT/MEK/ERK/mTOR pathways, as well as potential drug resistance mechanisms mediated by upregulation of Mcl-1 and RAS/RAF/MEK/ERK pathways. In summary, these findings support subclassification of DLBCL/HGBCL with dual MYC/TP53 alterations, which demonstrates distinct pathobiologic features and dismal survival with standard therapy, therefore requiring additional targeted therapies. IMPLICATIONS: The clinical and pharmacologic studies suggest recognizing DLBCL with concomitant TP53 mutation and MYC abnormalities as a distinctive entity necessary for precision oncology practice. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/2/249/F1.large.jpg.

Aggressive B-cell lymphomas with a primary bone marrow presentation

Aggressive B-cell lymphomas present as a heterogeneous spectrum of disease. A primary diagnosis in the bone marrow (BM) may be challenging in terms of diagnostic classification and clinical handling, owing to limited architectural information. Aggressive B-cell lymphomas can be subdivided into entities that typically present primarily in the BM, and cases with BM involvement in which the bulk of disease is present in other organs. One main topic at the 2018 BM workshop of the European Association of Haematopathology/Society of Hematopathology was therefore aggressive B-cell lymphomas with a primary BM presentation. The spectrum of cases submitted to this topic gave a good overview of commonly encountered problems, as well as unusual manifestations, and highlighted areas of imprecise disease definitions and diagnostic grey zones. The categories submitted to the workshop included cases of Burkitt lymphoma (BL) with unusual features, high-grade B-cell lymphomas (HG-BCLs) with and without so-called double/triple-hit, and diffuse large B-cell lymphomas (DLBCLs) with a primary BM presentation. Areas of difficulties included the morphological boundaries of HG-BCL not otherwise specified, cases with MYC and bcl-2 or bcl-6 translocations and terminal deoxynucleotidyl transferase (TdT) expression, which were categorised as B-cell lymphoblastic leukaemia/lymphoma if most cells showed TdT positivity, and the clinicopathological overlap between intravascular large B-cell lymphoma, CD5-positive DLBCL, and DLBCL with primary presentations in the BM, spleen, and liver. This review summarises our understanding of the main aggressive B-cell lymphoma categories with a common primary BM presentation and potential problem areas, and makes suggestions for the immunophenotypic and genetic work-up, illustrated by the interesting and challenging cases submitted to the workshop.

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.