Molecular diagnosis of Burkitt's lymphoma

Molecular targets of glucocorticoids that elucidate their therapeutic efficacy in aggressive lymphomas

Glucocorticoids have been used for decades to treat lymphomas without an established mechanism of action. Using functional genomic, proteomic, and chemical screens, we discover that glucocorticoids inhibit oncogenic signaling by the B cell receptor (BCR), a recurrent feature of aggressive B cell malignancies, including diffuse large B cell lymphoma and Burkitt lymphoma. Glucocorticoids induce the glucocorticoid receptor (GR) to directly transactivate genes encoding negative regulators of BCR stability (LAPTM5; KLHL14) and the PI3 kinase pathway (INPP5D; DDIT4). GR directly represses transcription of CSK, a kinase that limits the activity of BCR-proximal Src-family kinases. CSK inhibition attenuates the constitutive BCR signaling of lymphomas by hyperactivating Src-family kinases, triggering their ubiquitination and degradation. With the knowledge that glucocorticoids disable oncogenic BCR signaling, they can now be deployed rationally to treat BCR-dependent aggressive lymphomas and used to construct mechanistically sound combination regimens with inhibitors of BTK, PI3 kinase, BCL2, and CSK.

B-cell non-Hodgkin lymphomas

B-cell lymphomas occur with an incidence of 20 new cases per 100 000 people per year in high-income countries. They can affect any organ and are characterised by heterogeneous clinical presentations and courses, varying from asymptomatic, to indolent, to very aggressive cases. Since the topic of B-cell non-Hodgkin lymphomas was last reviewed in The Lancet in 2017, a deeper understanding of the biological background of this heterogeneous group of malignancies, the availability of new diagnostic methods, and the development and implementation of new targeted and immunotherapeutic approaches have improved our ability to treat patients. This Seminar provides an overview of the pathobiology, classification, and prognostication of B-cell non-Hodgkin lymphomas and summarises the current knowledge and standard of care regarding biology and clinical management of the most common subtypes of mature B-cell non-Hodgkin lymphomas. It also highlights new findings in deciphering the molecular background of disease development and the implementation of new therapeutic approaches, particularly those targeting the immune system.

A genetic profiling guideline to support diagnosis and clinical management of lymphomas

The new lymphoma classifications (International Consensus Classification of Mature Lymphoid Neoplasms, and 5th World Health Organization Classification of Lymphoid Neoplasms) include genetics as an integral part of lymphoma diagnosis, allowing better lymphoma subclassification, patient risk stratification, and prediction of treatment response. Lymphomas are characterized by very few recurrent and disease-specific mutations, and most entities have a heterogenous genetic landscape with a long tail of recurrently mutated genes. Most of these occur at low frequencies, reflecting the clinical heterogeneity of lymphomas. Multiple studies have identified genetic markers that improve diagnostics and prognostication, and next-generation sequencing is becoming an essential tool in the clinical laboratory. This review provides a "next-generation sequencing" guide for lymphomas. It discusses the genetic alterations of the most frequent mature lymphoma entities with diagnostic, prognostic, and predictive potential and proposes targeted sequencing panels to detect mutations and copy-number alterations for B- and NK/T-cell lymphomas.

Latent Epstein-Barr virus infection collaborates with Myc over-expression in normal human B cells to induce Burkitt-like Lymphomas in mice

Epstein-Barr virus (EBV) is an important cause of human lymphomas, including Burkitt lymphoma (BL). EBV+ BLs are driven by Myc translocation and have stringent forms of viral latency that do not express either of the two major EBV oncoproteins, EBNA2 (which mimics Notch signaling) and LMP1 (which activates NF-κB signaling). Suppression of Myc-induced apoptosis, often through mutation of the TP53 (p53) gene or inhibition of pro-apoptotic BCL2L11 (BIM) gene expression, is required for development of Myc-driven BLs. EBV+ BLs contain fewer cellular mutations in apoptotic pathways compared to EBV-negative BLs, suggesting that latent EBV infection inhibits Myc-induced apoptosis. Here we use an EBNA2-deleted EBV virus (ΔEBNA2 EBV) to create the first in vivo model for EBV+ BL-like lymphomas derived from primary human B cells. We show that cord blood B cells infected with both ΔEBNA2 EBV and a Myc-expressing vector proliferate indefinitely on a CD40L/IL21 expressing feeder layer in vitro and cause rapid onset EBV+ BL-like tumors in NSG mice. These LMP1/EBNA2-negative Myc-driven lymphomas have wild type p53 and very low BIM, and express numerous germinal center B cell proteins (including TCF3, BACH2, Myb, CD10, CCDN3, and GCSAM) in the absence of BCL6 expression. Myc-induced activation of Myb mediates expression of many of these BL-associated proteins. We demonstrate that Myc blocks LMP1 expression both by inhibiting expression of cellular factors (STAT3 and Src) that activate LMP1 transcription and by increasing expression of proteins (DNMT3B and UHRF1) known to enhance DNA methylation of the LMP1 promoters in human BLs. These results show that latent EBV infection collaborates with Myc over-expression to induce BL-like human B-cell lymphomas in mice. As NF-κB signaling retards the growth of EBV-negative BLs, Myc-mediated repression of LMP1 may be essential for latent EBV infection and Myc translocation to collaboratively induce human BLs.

Refractory Burkitt Lymphoma: Diagnosis and Interventional Strategies

Despite excellent results in frontline therapy, particularly in pediatric age, refractory Burkitt lymphoma still remains a therapeutic challenge, with dismal outcome. The prognosis is very poor, ranging from less than 10% to 30-40%, with longer survival only in transplanted patients. On account of the paucity of data, mostly reporting on small series of patients, with heterogeneous characteristics and salvage treatments, at present it is impossible to draw definitive conclusions on the treatment of choice for this difficult to treat subset of patients. New insights into Burkitt lymphoma/leukemia cell biology have led to the development of new drugs, currently being tested, directed at different specific targets. Herein, we describe the results so far reported in refractory Burkitt lymphoma/leukemia, with standard treatments and hematopoietic stem cell transplant, and we review the new targeted drugs currently under evaluation.

Adding a Gene Expression Profile Test to Aid Differential Diagnosis and Treatment in Aggressive Large B-Cell Lymphoma: An Early Exploratory Economic Evaluation

BACKGROUND AND OBJECTIVE

Adding gene expression profiles (GEPs) to the current diagnostic work-up of aggressive large B-cell lymphomas may lead to the reclassification of patients, treatment changes and improved outcomes. A GEP test is in development using TempO-Seq® technology to distinguish Burkitt lymphoma (BL) and primary mediastinal large B-cell lymphoma (PMBCL) from diffuse large B-cell lymphoma (DLBCL), and to classify patients with DLBLC and to predict the benefit of (e.g.) adding bortezomib to R-CHOP therapy (RB-CHOP). This study aims to estimate the potential impact of a GEP test on costs and health outcomes to inform pricing and evidence generation strategies.

METHODS

Three decision models were developed comparing diagnostic strategies with and without GEP signatures over a lifetime horizon using a UK health and social care perspective. Inputs were taken from a recent clinical trial, literature and expert opinion. We estimated the maximum price of the test using a threshold of Great Britain Pound (GBP) 30,000 per quality-adjusted life-year (QALY). Sensitivity analyses were conducted.

RESULTS

The estimated maximum threshold price for a combined test to be cost effective is GBP 15,352. At base-case values, the BL signature delivers QALY gains of 0.054 at an additional cost of GBP 275. This results in a net monetary benefit at a threshold of GBP 30,000 per QALY of GBP 1345. For PMBCL, the QALY gain was 0.0011 at a cost saving of GBP 406 and the net monetary benefit was GBP 437. The hazard ratio for the impact of treating BL less intensively must be at least 1.2 for a positive net monetary benefit. For identifying patients with the DLBCL subtype responsive to bortezomib, QALY gain was 0.2465 at a cost saving of GBP 6175, resulting in a net monetary benefit of GBP 13,570. In a probabilistic sensitivity analysis using 1000 simulations, a testing strategy was superior to a treat all with R-CHOP strategy in 81% of the simulations and with a cost saving in 92% assuming a cost price of zero.

CONCLUSIONS

Our estimates show that the combined test has a high probability of being cost effective. There is good quality evidence for the benefit of subtyping DLBCL but the evidence on the number of patients reclassified to or from BL and PMBCL and the impact of a more precise diagnosis and the cost of treatment is weak. The developers can use the price estimate to inform a return on investment calculations. Evidence will be required of how well the TempO-Seq® technology performs compared to the testing GEP technology used for subtyping in the recent clinical trial. For BL and PMBCL elements of the test, evidence would be required of the number of patients reclassified and improved costing information would be useful. The diagnostic and therapeutic environment in haematological malignancies is fast moving, which increases the risk for developers of diagnostic tests.

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.

Preclinical support for tumor protein D52 as a cancer vaccine antigen

Overexpressed tumor-associated antigens (TAAs) are a large group that includes proteins found at increased levels in tumors compared to healthy cells. Universal tumor expression can be defined as overexpression in all cancers examined as has been shown for Tumor Protein D52. TPD52 is an over expressed TAA actively involved in transformation, leading to increased proliferation and metastasis. TPD52 overexpression has been demonstrated in many human adult and pediatric malignancies. The murine orthologue of TPD52 (mD52) parallels normal tissue expression patterns and known functions of human TPD52 (hD52). Here in we present our preclinical studies over the past 15 years which have demonstrated that vaccine induced immunity against mD52 is effective against multiple cancers in murine models, without inducing autoimmunity against healthy tissues and cells.

Biological heterogeneity in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is heterogeneous both in clinical outcomes and the underlying disease biology. Over the last 2 decades, several different approaches for dissecting biological heterogeneity have emerged. Gene expression profiling (GEP) stratifies DLBCL into 3 broad groups (ABC, GCB, and DZsig/MHG), each with parallels to different normal mature B cell developmental states and prognostic implications. More recently, several different genomic approaches have been developed to categorize DLBCL based on the co-occurrence of tumor somatic mutations, identifying more granular biologically unified subgroups that complement GEP-based approaches. We review the molecular approaches and clinical evidence supporting the stratification of DLBCL patients based on tumor biology. By offering a platform for subtype-guided therapy, these divisions remain a promising avenue for improving patient outcomes, especially in subgroups with inferior outcomes with current standard-of-care therapy.

FCRL1 immunoregulation in B cell development and malignancy

Immunotherapeutic targeting of surface regulatory proteins and pharmacologic inhibition of critical signaling pathways has dramatically shifted our approach to the care of individuals with B cell malignancies. This evolution in therapy reflects the central role of the B cell receptor (BCR) signaling complex and its co-receptors in the pathogenesis of B lineage leukemias and lymphomas. Members of the Fc receptor-like gene family (FCRL1-6) encode cell surface receptors with complex tyrosine-based regulation that are preferentially expressed by B cells. Among them, FCRL1 expression peaks on naïve and memory B cells and is unique in terms of its intracellular co-activation potential. Recent studies in human and mouse models indicate that FCRL1 contributes to the formation of the BCR signalosome, modulates B cell signaling, and promotes humoral responses. Progress in understanding its regulatory properties, along with evidence for its over-expression by mature B cell leukemias and lymphomas, collectively imply important yet unmet opportunities for FCRL1 in B cell development and transformation. Here we review recent advances in FCRL1 biology and highlight its emerging significance as a promising biomarker and therapeutic target in B cell lymphoproliferative disorders.

Incidence of Burkitt lymphoma in the United States during 2000 to 2019

Burkitt lymphoma (BL) is an aggressive B-cell lymphoma that occurs worldwide. A study of BL in the US National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program during 1973 to 2005 (n = 3043) revealed three age-specific incidence peaks of BL and rates that were rising. We studied BL cases diagnosed in SEER 22 during 2000 to 2019 (n = 11 626) to investigate age-specific BL incidence rates and temporal trends. The age-standardized BL incidence rate was 3.96/million person-years, with a 2.85:1 male-to-female ratio. The BL rate among both Hispanic and White individuals was higher than in Black individuals (4.52, 4.12 vs 3.14). Age-specific BL rates showed peaks during pediatric, adult and elderly years in males and pediatric and elderly peaks in females. Based on 4524 BL cases with HIV status (SEER 13), only one peak in adult males (45 years) was observed. Overall age-standardized BL incidence rates rose 1.2%/year (not significant) up to 2009 then fell significantly by 2.4%/year thereafter. Temporal trends in BL rates during 2000 to 2019 varied with age group as pediatric BL rates rose 1.1%/year, while elderly BL rates fell 1.7%/year and adult BL rates rose 3.4%/year until 2007 before falling 3.1%/year thereafter. Overall survival from BL was 64% at 2 years, being highest in pediatric patients and lowest in Black and elderly individuals vs other subgroups. Survival improved by 20% between 2000 and 2019. Our data suggest that BL age-specific incidence rates are multimodal and that overall BL rates rose up to 2009 and then fell, suggesting changes in etiological factors or diagnosis.

MYC overexpression but not MYC/BCL2 double expression predicts survival in bulky mass diffuse large B-cell lymphoma patients

PURPOSE

The prognostic factors for diffuse large B-cell lymphoma (DLBCL) have been fully explored, but prognostic information for bulky mass DLBCL patients is limited. This study aimed to analyze the prognostic value of MYC protein expression and other biological parameters in bulky mass DLBCL patients.

METHODS

We defined a bulky mass as a maximum tumor diameter ≥7.5 cm and studied 227 patients with de novo bulky mass DLBCL.

RESULTS

In all patients with bulky mass DLBCL, the 1-year and 3-year OS rates were 72.7% and 57.1%, respectively, and the 1-year and 3-year PFS rates were 52.0% and 42.5%, respectively. The MYC overexpression group (n = 140) showed significantly worse overall survival (OS; p = 0.019) and progression-free survival (PFS; p = 0.001) than the non-MYC overexpression group (n = 87). Subgroup analyses demonstrated that the MYC overexpression group was associated with inferior OS and PFS in the subgroups with the International Prognostic Index score of 3-5 (OS: p = 0.011; PFS: p < 0.001), Ann Arbor stage 3-4 (OS: p = 0.014; PFS: p < 0.001) and GCB subtype (OS: p = 0.014; PFS: p = 0.010). Consolidation radiotherapy improved OS and PFS in patients with bulky mass DLBCL (OS: p = 0.008; PFS: p = 0.004) as well as in those with MYC overexpression (OS: p = 0.001; PFS: p = 0.001). The prognostic value of MYC overexpression was maintained in a multivariate model adjusted for the International Prognostic Index.

CONCLUSION

MYC overexpression is a poor predictor for bulky mass DLBCL patients. Consolidation radiotherapy for residual disease after induction therapy may improve outcomes for patients with bulky mass DLBCL.

Calcineurin-independent NFATc1 signaling is essential for survival of Burkitt lymphoma cells

In Burkitt lymphoma (BL), a tumor of germinal center B cells, the pro-apoptotic properties of MYC are controlled by tonic B cell receptor (BCR) signals. Since BL cells do not exhibit constitutive NF-κB activity, we hypothesized that anti-apoptotic NFATc1 proteins provide a major transcriptional survival signal in BL. Here we show that post-transcriptional mechanisms are responsible for the calcineurin (CN) independent constitutive nuclear over-expression of NFATc1 in BL and Eµ-MYC - induced B cell lymphomas (BCL). Conditional inactivation of the Nfatc1 gene in B cells of Eµ-MYC mice leads to apoptosis of BCL cells in vivo and ex vivo. Inhibition of BCR/SYK/BTK/PI3K signals in BL cells results in cytosolic re-location of NFATc1 and apoptosis. Therefore, NFATc1 activity is an integrated part of tonic BCR signaling and an alternative target for therapeutic intervention in BL.

OX40 shapes an inflamed tumor immune microenvironment and predicts response to immunochemotherapy in diffuse large B-cell lymphoma

OX40 enhances the T-cell activation via costimulatory signaling. However, its molecular characteristics and value in predicting response to immunochemotherapy in DLBCL remain largely unexplored. Here, we performed an integrative analysis of sequencing and multiplex immunofluorescence staining, and discovered abnormally higher expression of OX40 in DLBCL patients. Elevated OX40 could activate T cells leading to a higher immune score for tumor immune microenvironment (TiME). OX40 upregulation simultaneously happened with immune-related genes including PD-1, CTLA4 and TIGIT et,al. Patients with high OX40 expression exhibited a lower Ann Arbor stage and IPI score and more easily achieved a complete response/partial response. The analysis of infiltrated T-cell subset revealed that patients with a greater number of CD4+/OX40+ or CD8+/OX40+ T cells had a longer OS. Our findings indicated that OX40 shapes an inflamed tumor immune microenvironment and predicts response to immunochemotherapy, providing insights for the application of OX40 agonist in DLBCL patients.

Phosphorylation stabilized TET1 acts as an oncoprotein and therapeutic target in B cell acute lymphoblastic leukemia

Although the overall survival rate of B cell acute lymphoblastic leukemia (B-ALL) in childhood is more than 80%, it is merely 30% in refractory/relapsed and adult patients with B-ALL. This demonstrates a need for improved therapy targeting this subgroup of B-ALL. Here, we show that the ten-eleven translocation 1 (TET1) protein, a dioxygenase involved in DNA demethylation, is overexpressed and plays a crucial oncogenic role independent of its catalytic activity in B-ALL. Consistent with its oncogenic role in B-ALL, overexpression of TET1 alone in normal precursor B cells is sufficient to transform the cells and cause B-ALL in mice within 3 to 4 months. We found that TET1 protein is stabilized and overexpressed because of its phosphorylation mediated by protein kinase C epsilon (PRKCE) and ATM serine/threonine kinase (ATM), which are also overexpressed in B-ALL. Mechanistically, TET1 recruits STAT5B to the promoters of CD72 and JCHAIN and promotes their transcription, which in turn promotes B-ALL development. Destabilization of TET1 protein by treatment with PKC or ATM inhibitors (staurosporine or AZD0156; both tested in clinical trials), or by pharmacological targeting of STAT5B, greatly decreases B-ALL cell viability and inhibits B-ALL progression in vitro and in vivo. The combination of AZD0156 with staurosporine or vincristine exhibits a synergistic effect on inhibition of refractory/relapsed B-ALL cell survival and leukemia progression in PDX models. Collectively, our study reveals an oncogenic role of the phosphorylated TET1 protein in B-ALL independent of its catalytic activity and highlights the therapeutic potential of targeting TET1 signaling for the treatment of refractory/relapsed B-ALL.

Improving outcomes of childhood and young adult non-Hodgkin lymphoma: 25 years of research and collaboration within the framework of the European Intergroup for Childhood Non-Hodgkin Lymphoma

The European Intergroup for Childhood Non-Hodgkin Lymphoma (EICNHL) was established 25 years ago with the goal to facilitate clinical trials and research collaborations in the field both within Europe and worldwide. Since its inception, much progress has been made whereby major improvements in outcomes have been achieved. In this Review, we describe the different diagnostic entities of non-Hodgkin lymphoma in children and young adults describing key features of each entity and outlining clinical achievements made in the context of the EICNHL framework. Furthermore, we provide an overview of advances in biopathology with an emphasis on the role of biological studies and how they have shaped available treatments. Finally, for each entity, we describe future goals, upcoming clinical trials, and highlight areas of research that require our focus going forward.

Diagnostic approaches and future directions in Burkitt lymphoma and high-grade B-cell lymphoma

Since the 2016 WHO update, progress has been made in understanding the biology of Burkitt lymphoma (BL) and the concept of high-grade B-cell lymphomas (HGBCL) that allows some degree of refinement. The summary presented here reviews in detail the discussions of the Clinical Advisory Committee and expands upon the newly published 2022 International Consensus Classification for lymphoid malignancies (Campo et al. Blood, 2022). BL remains the prototypic HGBCL and diagnostic criteria are largely unchanged. HGBCL with MYC and BCL2 and HGBCL with MYC and BCL6 rearrangements are now separated to reflect biologic and pathologic differences. HGBCL, NOS remains a diagnosis of exclusion that should be used only in rare cases. FISH strategies for diffuse large B-cell lymphoma (DLBCL) and HGBCL are discussed in detail for these diseases. Advances in integrative analysis of mutations, structural abnormalities, copy number, and gene expression signatures allow a more nuanced view of the heterogeneity of DLBCL, NOS as well as definitions of HGBCL and point to where the future may be headed for classification of these diseases.

Gene Expression Signatures for the Accurate Diagnosis of Peripheral T-Cell Lymphoma Entities in the Routine Clinical Practice

PURPOSE

Peripheral T-cell lymphoma (PTCL) includes heterogeneous clinicopathologic entities with numerous diagnostic and treatment challenges. We previously defined robust transcriptomic signatures that distinguish common PTCL entities and identified two novel biologic and prognostic PTCL-not otherwise specified subtypes (PTCL-TBX21 and PTCL-GATA3). We aimed to consolidate a gene expression-based subclassification using formalin-fixed, paraffin-embedded (FFPE) tissues to improve the accuracy and precision in PTCL diagnosis.

MATERIALS AND METHODS

We assembled a well-characterized PTCL training cohort (n = 105) with gene expression profiling data to derive a diagnostic signature using fresh-frozen tissue on the HG-U133plus2.0 platform (Affymetrix, Inc, Santa Clara, CA) subsequently validated using matched FFPE tissues in a digital gene expression profiling platform (nCounter, NanoString Technologies, Inc, Seattle, WA). Statistical filtering approaches were applied to refine the transcriptomic signatures and then validated in another PTCL cohort (n = 140) with rigorous pathology review and ancillary assays.

RESULTS

In the training cohort, the refined transcriptomic classifier in FFPE tissues showed high sensitivity (> 80%), specificity (> 95%), and accuracy (> 94%) for PTCL subclassification compared with the fresh-frozen-derived diagnostic model and showed high reproducibility between three independent laboratories. In the validation cohort, the transcriptional classifier matched the pathology diagnosis rendered by three expert hematopathologists in 85% (n = 119) of the cases, showed borderline association with the molecular signatures in 6% (n = 8), and disagreed in 8% (n = 11). The classifier improved the pathology diagnosis in two cases, validated by clinical findings. Of the 11 cases with disagreements, four had a molecular classification that may provide an improvement over pathology diagnosis on the basis of overall transcriptomic and morphological features. The molecular subclassification provided a comprehensive molecular characterization of PTCL subtypes, including viral etiologic factors and translocation partners.

CONCLUSION

We developed a novel transcriptomic approach for PTCL subclassification that facilitates translation into clinical practice with higher precision and uniformity than conventional pathology diagnosis.

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.

Complex genetic and histopathological study of 15 patient-derived xenografts of aggressive lymphomas

Non-Hodgkin lymphomas (NHL) represent the most common hematologic malignancies. Patient-derived xenografts (PDXs) are used for various aspects of translational research including preclinical in vivo validation of experimental treatment approaches. While it was repeatedly demonstrated that PDXs keep majority of somatic mutations with the primary lymphoma samples, from which they were derived, the composition of PDX tumor microenvironment (TME) has not been extensively studied. We carried out a comparative genetic and histopathological study of 15 PDX models derived from patients with various types of NHL including diffuse large B-cell lymphoma (DLBCL; n = 7), Burkitt lymphoma (BL; n = 1), mantle cell lymphoma (MCL; n = 2), and peripheral T-cell lymphomas (PTCL; n = 5). Whole exome sequencing (WES) of the PDXs and primary lymphoma cells was implemented in 13 out of 15 cases with available DNA samples. Standard immunohistochemistry (IHC) was used to analyze the composition of PDX TME. WES data confirmed that PDXs maintained the genetic heterogeneity with the original primary lymphoma cells. In contrast, IHC analysis revealed the following recurrently observed alterations in the composition of PDX tumors: more blastoid lymphoma cell morphology, increased proliferation rate, lack of non-malignant cellular components including T cells and (human or murine) macrophages, and significantly lower intratumoral microvessel density and microvessel area composed of murine vessels. In addition, PDX tumors derived from T-NHL displayed additional differences compared to the primary lymphoma samples including markedly lower desmoplasia (i.e., the extent of both reticular and collagen fibrosis), loss of expression of cytotoxic granules (i.e., perforin, TIA, granzyme B), or loss of expression of T-cell specific antigens (i.e., CD3, CD4, CD8). Our data suggest that despite keeping the same genetic profiles, PDX models of aggressive NHL do not recapitulate the microenvironmental heterogeneity of the original lymphomas. These findings have implications on the relevance of PDX models in the context of preclinical research.

Towards precision medicine in lymphoid malignancies

Careful histopathologic examination remains the cornerstone in the diagnosis of the clinically and biologically heterogeneous group of lymphoid malignancies. However, recent advances in genomic and epigenomic characterization using high-throughput technologies have significantly improved our understanding of these tumors. Although no single genomic alteration is completely specific for a lymphoma entity, some alterations are highly recurrent in certain entities and thus can provide complementary diagnostic information when integrated in the hematopathological diagnostic workup. Moreover, other alterations may provide important information regarding the clinical course, that is, prognostic or risk-stratifying markers, or response to treatment, that is, predictive markers, which may allow tailoring of the patient's treatment based on (epi)genetic characteristics. In this review, we will focus on clinically relevant diagnostic, prognostic, and predictive biomarkers identified in more common types of B-cell malignancies, and discuss how diagnostic assays designed for comprehensive molecular profiling may pave the way for the implementation of precision diagnostics/medicine approaches. We will also discuss future directions in this rapidly evolving field, including the application of single-cell sequencing and other omics technologies, to decipher clonal dynamics and evolution in lymphoid malignancies.

A brief overview of the Epstein Barr virus and its association with Burkitt's lymphoma

Epstein Barr virus (EBV) is known as an oncovirus and associates with several human malignancies such as Burkitt's lymphoma, other non-Hodgkin lymphomas, nasopharyngeal carcinoma, Hodgkin's disease, gastric adenocarcinoma, etc. in Burkitt's lymphoma, and the key event is the translocation of MYC gene, that increase of cell survival and aberrant expression of MYC gene. The biology of EBV and its function in the development of Burkitt's lymphoma are discussed in this review

CD24 is a surrogate for 'immune-cold' phenotype in aggressive large B-cell lymphoma

The tumor microenvironment (TME) is a critical regulator of the development of malignant lymphoma. Therapeutics targeting the TME, especially immune checkpoint molecules, are changing the treatment strategy for lymphoma. However, the overall response to these therapeutics for diffuse large B‐cell lymphoma (DLBCL) is modest and new targets of immunotherapy are needed. To find critical immune checkpoint molecules for DLBCL, we explored the prognostic impact of immune checkpoint molecules and their ligands using publicly available datasets of gene expression profiles. In silico analysis of three independent datasets (GSE117556, GSE10846, and GSE181063) revealed that DLBCL expressing CD24 had a poor prognosis and had a high frequency of MYC aberrations. Moreover, gene set enrichment analysis showed that the ‘MYC‐targets‐hallmark’ (false discovery rate [FDR] = 0.024) and ‘inflammatory‐response‐hallmark’ (FDR = 0.001) were enriched in CD24‐high and CD24‐low DLBCL, respectively. In addition, the expression of cell‐specific markers of various immune cells was higher in CD24‐low DLBCL than in CD24‐high DLBCL. CIBERSORT analysis of the datasets showed fewer macrophages in CD24‐high DLBCL than in CD24‐low DLBCL. Additionally, immunohistochemical analysis of 335 cases of DLBCL showed that few TME cells were found in CD24‐high DLBCL, although statistical differences were not observed. These data indicate that CD24 expression suppresses immune cell components of the TME in DLBCL, suggesting that CD24 may be a target for cancer immunotherapy in aggressive large B‐cell lymphoma.

Latent Membrane Proteins from EBV Differentially Target Cellular Pathways to Accelerate MYC-induced Lymphomagenesis

EBV LMP1 enhances MYC-mediated degradation of the p27kip1 tumor suppressor and accelerates MYC-induced lymphomagenesis.

EBV LMP1 and LMP2A differentially use G1-specific cell cycle and BCR-mediated signaling to accelerate MYC-induced lymphomagenesis.

MYC translocations in association with Epstein-Barr virus (EBV) infection are often observed in B-cell lymphomas. A subset of Burkitt lymphoma (BL) expresses EBV latent membrane proteins 1 and 2A (LMP1 and LMP2A) in addition to the typical restricted EBV latent gene expression. EBV-associated diffuse large B-cell lymphoma (DLBCL) typically exhibits latency type II or III and expresses LMP1. Here, we investigate the role of LMP1 in MYC-driven lymphomagenesis in our murine model. λ-MYC mice develop tumors having a “starry sky” appearance and have abnormal p53 expression that is also observed in human BL. LMP2A/λ-MYC double-transgenic mice develop tumors significantly faster than mice only expressing MYC. Similar to LMP2A/λ-MYC mice, LMP1/λ-MYC mice also have accelerated MYC-driven lymphomagenesis. As observed in LMP2A/λ-MYC mice, p27^kip1 was degraded in LMP1/λ-MYC pretumor and tumor B cells. Coexpression of LMP1 and LMP2A resulted in the enhancement of B cell proliferation. In contrast to LMP2A, the inhibition of Syk or cyclin-dependant kinase (CDK)4/6 activity did not effectively inhibit LMP1-mediated MYC lymphomagenesis. Also, in contrast to LMP2A, LMP1 did not lessen abnormal p53 expression in λ-MYC tumors. To investigate the significance of LMP1 expression in human BL development, we reanalyzed RNA sequencing (RNA-Seq) data of primary human BL from previous studies. Interestingly, p53 mutations were less observed in LMP1-expressing BL, although they were not significantly changed by EBV infection, indicating LMP1 may lessen p53 mutations in human primary BL. This suggests that LMP1 effects in EBV-associated human BL vary from what we observe in our murine model. Finally, our studies suggest a novel pathogenic role of LMP1 in lymphomagenesis.

CD24 Is a Potential Immunotherapeutic Target for Mantle Cell Lymphoma

CD24 and its ligand Siglec-10 were described as an innate immune checkpoint in carcinoma. Here, we investigated this axis in B-cell lymphoma by assessing CD24 expression and evaluating pro-phagocytic effects of CD24 antibody treatment in comparison to hallmark immune checkpoint CD47. In mantle cell lymphoma (MCL) and follicular lymphoma patients, high mRNA expression of CD24 correlated with poor overall survival, whereas CD47 expression did not. Conversely, CD24 expression did not correlate with survival in diffuse large B-cell lymphoma (DLBCL), whereas CD47 did. CD24 was also highly expressed on MCL cell lines, where treatment with CD24 antibody clones SN3 or ML5 potently induced phagocytosis, with SN3 yielding >90% removal of MCL cells and triggering phagocytosis of primary patient-derived MCL cells by autologous macrophages. Treatment with CD24 mAb was superior to CD47 mAb in MCL and was comparable in magnitude to the effect observed in carcinoma lines. Reversely, CD24 mAb treatment was less effective than CD47 mAb treatment in DLBCL. Finally, phagocytic activity of clone SN3 appeared at least partly independent of antibody-dependent cellular phagocytosis (ADCP), suggesting CD24/Siglec-10 checkpoint activity, whereas clone ML5 solely induced ADCP. In conclusion, CD24 is an immunotherapeutic target of potential clinical relevance for MCL, but not DLBCL.

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.

RNA-seq and integrated network analysis reveals the hub genes and key pathway of paclitaxel inhibition on Adriamycin resistant diffuse large B cell lymphoma cells

About 40% of patients with diffuse large B-cell lymphoma (DLBCL) develop drug resistance after first-line chemotherapy, which remains a major cause of morbidity and mortality. The emergence of DLBCL drug resistance is mainly related to Adriamycin. Our previous research shows that Paclitaxel could be a potential therapeutic drug for the treatment of Adriamycin-resistant DLBCL. Based on the results of RNA-seq and integrated network analysis, we study the potential molecular mechanism of Paclitaxel in the treatment of Adriamycin-resistant DLBCL in multiple dimensions. A CCK-8 assay showed that the inhibitory effect of Paclitaxel on Pfeiffer and Pfeiffer/ADM (Adriamycin-resistant DLBCL cell lines) is significantly higher than that of Adriamycin (P ＜ 0.05). Five hub genes (UBC, TSR1, WDR46, HSP90AA1, and NOP56) were obtained via network analysis from 971 differentially expressed genes (DEGs) based on the RNA-seq of Paclitaxel-intervened Pfeiffer/ADM. The results of the network function module analysis showed that the inhibition of Pfeiffer/ADM by Paclitaxel was closely related to ribosome biosynthesis in eukaryotes. The results of RT-qPCR showed that the mRNA levels of the five hub genes in the Pfeiffer/ADM group were significantly lower than those in the Pfeiffer group and the Pfeiffer/ADM Paclitaxel-treated group (P ＜ 0.05). Consistent with studies, Paclitaxel exhibited a significant inhibitory effect on Adriamycin-resistant DLBCL, which may have played a role in the five hub genes (UBC, TSR1, WDR46, HSP90AA1 and NOP56) and ribosome biosynthesis in eukaryotes pathway, but the specific regulation needs further experimental verification.

Aggressive B-cell lymphoma cases with 11q aberration patterns indicate a spectrum beyond Burkitt-like lymphoma

The recent characterization of a group of non-MYC rearranged aggressive B-cell lymphomas, resembling Burkitt lymphoma (BL), characteristically harboring a telomeric 11q loss or combined 11q proximal gains/loss pattern has led to the introduction of the provisional entity of Burkitt-like lymphoma with 11q aberration (BLL-11q). Prompted by the discovery of a telomeric 11q loss in an HIV+ high-grade B-cell lymphoma patient, we investigated an extended cohort of aggressive B-cell lymphomas, enriched for cases with histopathological features intermediate between DLBCL and BL, including double- and triple-hit lymphomas (n = 47), for 11q loss/combined 11q proximal gains/loss pattern by fluorescence in situ hybridization. We provide first evidence that 11q aberrations can be found in both BLL in the context of an underlying HIV infection as well as in high-grade B-cell lymphomas with MYC, BCL2, and/or BCL6 rearrangements. We therefore propose that the clinicopathological spectrum of malignancies carrying this aberration may be broader than previously assumed.

Accuracy of Pathologic Diagnosis in Patients With Lymphoma and Survival: A Prospective Analysis From Botswana

PURPOSE

With intense HIV epidemics, southern African countries have a high burden of classic Hodgkin lymphoma (CHL) and non-Hodgkin lymphoma (NHL). However, suboptimal access to pathology resources limits subtype classification. We sought to assess the diagnostic accuracy of specimens classified as lymphoma and to determine association between discordant pathologic diagnosis and overall survival.

METHODS

Seventy patients with CHL or NHL and treated at three Botswana hospitals from 2010 to 2016 were analyzed. Local pathologic assessment relied primarily on morphology. All cases underwent secondary US hematopathology review, which is considered gold standard.

RESULTS

The median follow-up was 58 months. The overall reclassification rate was 20 of 70 cases (29%). All 20 CHL cases were correctly classified in Botswana, and mixed cellularity was the most common subtype, diagnosed in 11 (55%) cases. Of 47 confirmed NHL cases, diffuse large B-cell lymphoma was the final US diagnosis in 28 cases (60%), another aggressive B-cell NHL in nine (19%), an indolent B-cell NHL in six (13%), and T-cell NHL in four (9%). Common types of diagnostic discordance included NHL subtype reclassification (11 of 20, 55%) and CHL reclassified as NHL (7 of 20, 35%). Concordant versus discordant diagnosis after secondary review was associated with improved 5-year overall survival (60.1% v 26.3%, P = .0066). Discordant diagnosis was independently associated with increased risk of death (adjusted hazard ratio 2.733; 95% CI, 1.102 to 6.775; P = .0300) even after stratifying results by CHL versus NHL.

CONCLUSION

In this single prospective cohort, discordant pathologic diagnosis was associated with a nearly three-fold increased risk of death. Limited access to relatively basic diagnostic techniques impairs treatment decisions and leads to poor patient outcomes in low-resource countries.

Differential Transcriptional Reprogramming by Wild Type and Lymphoma-Associated Mutant MYC Proteins as B-Cells Convert to a Lymphoma Phenotype

The MYC transcription factor regulates a vast number of genes and is implicated in many human malignancies. In some hematological malignancies, MYC is frequently subject to missense mutations that enhance its transformation activity. Here, we use a novel murine cell system to (i) characterize the transcriptional effects of progressively increasing MYC levels as normal primary B-cells transform to lymphoma cells and (ii) determine how this gene regulation program is modified by lymphoma-associated MYC mutations (T58A and T58I) that enhance its transformation activity. Unlike many previous studies, the cell system exploits primary B-cells that are transduced to allow regulated MYC expression under circumstances where apoptosis and senescence pathways are abrogated by the over-expression of the Bcl-xL and BMI1 proteins. In such cells, transition from a normal to a lymphoma phenotype is directly dependent on the MYC expression level, without a requirement for secondary events that are normally required during MYC-driven oncogenic transformation. A generalized linear model approach allowed an integrated analysis of RNA sequencing data to identify regulated genes in relation to both progressively increasing MYC level and wild type or mutant status. Using this design, a total of 7569 regulated genes were identified, of which the majority (n = 7263) were regulated in response to progressively increased levels of wild type MYC, while a smaller number of genes (n = 917) were differentially regulated, compared to wild type MYC, in T58A MYC- and/or T58I MYC-expressing cells. Unlike most genes that are similarly regulated by both wild type and mutant MYC genes, the set of 917 genes did not significantly overlap with known lipopolysaccharide regulated genes, which represent genes regulated by MYC in normal B cells. The genes that were differently regulated in cells expressing mutant MYC proteins were significantly enriched in DNA replication and G2 phase to mitosis transition genes. Thus, mutants affecting MYC proteins may augment quantitative oncogenic effects on the expression of normal MYC-target genes with qualitative oncogenic effects, by which sets of cell cycle genes are abnormally targeted by MYC as B cells transition into lymphoma cells. The T58A and T58I mutations augment MYC-driven transformation by distinct mechanisms.

Transcription factor 3 (TCF3) combined with histone deacetylase 3 (HDAC3) down-regulates microRNA-101 to promote Burkitt lymphoma cell proliferation and inhibit apoptosis

To explore the function of transcription factor 3 (TCF3) on the proliferation and apoptosis of Burkitt lymphoma cells and its mechanism. qRT-PCR was performed to determine the expression of TCF3, histone deacetylase 3 (HDAC3), and microRNA-101 (miR-101) in the Burkitt lymphoma (BL) tumor tissues and lymph node tissues with reactive lymph node hyperplasia (RLNH). We found that the expression of TCF3 and HDAC3 was up-regulated in BL tumor tissues and lymphoma cells, and the miR-101 expression was down-regulated. And TCF3 and HDAC3 were negatively correlated with the expression of miR-101, respectively. In addition, knockdown of TCF3 can inhibit BL cell proliferation, reduce cell viability and promote cell apoptosis, retain the cell cycle in the G0/G1 phase, and inhibit the expression of Akt/mTOR pathway-related proteins (p-Akt and p-mTOR). When miR-101 was overexpressed, the results were the same as when TCF3 was knocked down. Moreover, we used Co-immunoprecipitation (Co-IP) to detect the interaction between TCF3 and HDAC3, and performed the Chromatin immunoprecipitation (ChIP) experiment to detect the enrichment of TCF3 and HDAC3 in the promoter region of miR-101. We found that TCF3 can interact with HDAC3 and is enriched in the miR-101 promoter region. In conclusion, TCF3 combined with HDAC3 down-regulates the expression of miR-101, thereby promoting the proliferation of BL cells and inhibiting their apoptosis.

Epstein-Barr virus status of sporadic Burkitt lymphoma is associated with patient age and mutational features

Sporadic Burkitt lymphoma (BL) is the most frequent tumour of children and adolescents but a rare subtype of lymphomas in adults. To date most molecular data have been obtained from lymphomas arising in the young. Recently, Epstein-Barr virus (EBV) positive and negative BL in young patients was shown to differ in molecular features. In the present study, we present a large age-overarching cohort of sporadic BL (n = 162) analysed by immunohistochemistry, translocations of MYC proto-oncogene, basic helix-loop-helix transcription factor (MYC), B-cell leukaemia/lymphoma 2 (BCL2) and B-cell leukaemia/lymphoma 6 (BCL6) and by targeted sequencing. We illustrate an age-associated inter-tumoral molecular heterogeneity in this disease. Mutations affecting inhibitor of DNA binding 3, HLH protein (ID3), transcription factor 3 (TCF3) and cyclin D3 (CCND3), which are highly recurrent in paediatric BL, and expression of sex determining region Y-box transcription factor 11 (SOX11) declined with patient age at diagnosis (P = 0·0204 and P = 0·0197 respectively). In contrast, EBV was more frequently detected in adult patients (P = 0·0262). Irrespective of age, EBV-positive sporadic BL showed significantly less frequent mutations in ID3/TCF3/CCND3 (P = 0·0088) but more often mutations of G protein subunit alpha 13 (GNA13; P = 0·0368) and forkhead box O1 (FOXO1; P = 0·0044) compared to EBV-negative tumours. Our findings suggest that among sporadic BL an EBV-positive subgroup of lymphomas increases with patient age that shows distinct pathogenic features reminiscent of EBV-positive endemic BL.

Targeting Asparagine and Serine Metabolism in Germinal Centre-Derived B Cells Non-Hodgkin Lymphomas (B-NHL)

BL and DLBCL are subtypes of B-cell lymphomas that arise from germinal centre B lymphocytes. Differentiation between BL and DLBCL is critical and can be challenging, as these two types of cancer share the same morphological, immunophenotypic, and genetic characteristics. In this study, we have examined metabolism in BL and DLBCL lymphomas and found distinctive differences in serine metabolism. We show that BL cells consume significantly more extracellular asparagine than DLBCL cells. Using a tracer-based approach, we find that asparagine regulates the serine uptake and serine synthesis in BL and DLBCL cells. Calculation of Differentially Expressed Genes (DEGs) from RNAseq datasets of BL and DLBCL patients show that BL cancers express the genes involved in serine synthesis at a higher level than DLBCL. Remarkably, combined use of an inhibitor of serine biosynthesis pathway and an anticancer drug asparaginase increases the sensitivity of BL cells to extracellular asparagine deprivation without inducing a change in the sensitivity of DLBCL cells to asparaginase. In summary, our study unravels metabolic differences between BL and DLBCL with diagnostic potential which may also open new avenues for treatment.

Prognostic impact of a lymphocyte activation-associated gene signature in GBM based on transcriptome analysis

Background

Glioblastoma multiforme (GBM) is a highly, malignant tumor of the primary central nervous system. Patients diagnosed with this type of tumor have a poor prognosis. Lymphocyte activation plays important roles in the development of cancers and its therapeutic treatments.

Objective

We sought to identify an efficient lymphocyte activation-associated gene signature that could predict the progression and prognosis of GBM.

Methods

We used univariate Cox proportional hazards regression and stepwise regression algorithm to develop a lymphocyte activation-associated gene signature in the training dataset (TCGA, n = 525). Then, the signature was validated in two datasets, including GSE16011 (n = 150) and GSE13041 (n = 191) using the Kaplan Meier method. Univariate and multivariate Cox proportional hazards regression models were used to adjust for clinicopathological factors.

Results

We identified a lymphocyte activation-associated gene signature (TCF3, IGFBP2, TYRO3 and NOD2) in the training dataset and classified the patients into high-risk and low-risk groups with significant differences in overall survival (median survival 15.33 months vs 12.57 months, HR = 1.55, 95% CI [1.28-1.87], log-rank test P < 0.001). This signature showed similar prognostic values in the other two datasets. Further, univariate and multivariate Cox proportional hazards regression models analysis indicated that the signature was an independent prognostic factor for GBM patients. Moreover, we determined that there were differences in lymphocyte activity between the high- and low-risk groups of GBM patients among all datasets. Furthermore, the lymphocyte activation-associated gene signature could significantly predict the survival of patients with certain features, including IDH-wildtype patients and patients undergoing radiotherapy. In addition, the signature may also improve the prognostic power of age.

Conclusions

In summary, our results suggested that the lymphocyte activation-associated gene signature is a promising factor for the survival of patients, which is helpful for the prognosis of GBM patients.

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.

The treatment of Burkitt lymphoma in adults

Burkitt lymphoma (BL) is a highly aggressive, B-cell, non-Hodgkin lymphoma categorized into endemic, sporadic, and immunodeficiency-associated subtypes. BL has distinct pathologic and clinical features, characterized by rapidly progressive tumors with high rates of extranodal involvement. Next-generation-sequencing analyses have further characterized the genomic landscape of BL and our understanding of disease pathogenesis, although these findings have yet to influence treatment. Although most patients are cured with intensive combination chemotherapy, given the paucity of randomized trials, optimal therapy has not been defined. Furthermore, treatment of elderly patients, patients with central nervous system involvement, or those with relapsed disease remains an unmet need. In this review, we highlight the clinical, pathologic, and genomic features, as well as standard and emerging treatment options for adult patients with BL.

Novel Biological Insights and New Developments in Management of Burkitt Lymphoma and High-Grade B-Cell Lymphoma

OPINION STATEMENT

Burkitt lymphoma (BL) is highly curable, and prompt institution of therapy is critical to achieving optimal outcomes. Although current "standard" approaches are very effective in disease eradication, treatment-related toxicity makes optimal delivery of curative therapy a challenge, especially in older and immunocompromised individuals. Reduced intensity approaches with fewer toxic complications have been the focus of some recent studies. A critical question is if they can replace "standard" approaches by maintaining high curability with improved tolerability. Additionally, new molecular insights in BL biology suggest that in the future, "targeted therapy" approaches may be feasible using small molecule inhibitors and novel strategies. Recently, a new category of aggressive lymphoma named "high-grade B-cell lymphoma (HGBL) with MYC and BCL2 and/or BCL6 translocations" has been recognized. This category overlaps clinically and biologically with BL and has an inferior prognosis compared to most B-cell lymphomas, and the optimal approach to its management remains, as yet, undefined. In this review, we discuss the current landscape of BL treatment including recent results with low-intensity regimens and also consider current approaches to HGBL. We also explore how recently elucidated novel biological insights in BL biology may shape future therapeutic directions including the use of novel cellular therapy approaches.

Low-cost transcriptional diagnostic to accurately categorize lymphomas in low- and middle-income countries

Inadequate diagnostics compromise cancer care across lower- and middle-income countries (LMICs). We hypothesized that an inexpensive gene expression assay using paraffin-embedded biopsy specimens from LMICs could distinguish lymphoma subtypes without pathologist input. We reviewed all biopsy specimens obtained at the Instituto de Cancerología y Hospital Dr. Bernardo Del Valle in Guatemala City between 2006 and 2018 for suspicion of lymphoma. Diagnoses were established based on the World Health Organization classification and then binned into 9 categories: nonmalignant, aggressive B-cell, diffuse large B-cell, follicular, Hodgkin, mantle cell, marginal zone, natural killer/T-cell, or mature T-cell lymphoma. We established a chemical ligation probe-based assay (CLPA) that quantifies expression of 37 genes by capillary electrophoresis with reagent/consumable cost of approximately $10/sample. To assign bins based on gene expression, 13 models were evaluated as candidate base learners, and class probabilities from each model were then used as predictors in an extreme gradient boosting super learner. Cases with call probabilities < 60% were classified as indeterminate. Four (2%) of 194 biopsy specimens in storage <3 years experienced assay failure. Diagnostic samples were divided into 70% (n = 397) training and 30% (n = 163) validation cohorts. Overall accuracy for the validation cohort was 86% (95% confidence interval [CI]: 80%-91%). After excluding 28 (17%) indeterminate calls, accuracy increased to 94% (95% CI: 89%-97%). Concordance was 97% for a set of high-probability calls (n = 37) assayed by CLPA in both the United States and Guatemala. Accuracy for a cohort of relapsed/refractory biopsy specimens (n = 39) was 79% and 88%, respectively, after excluding indeterminate cases. Machine-learning analysis of gene expression accurately classifies paraffin-embedded lymphoma biopsy specimens and could transform diagnosis in LMICs.

Design of new disubstituted imidazo[1,2-b]pyridazine derivatives as selective Haspin inhibitors. Synthesis, binding mode and anticancer biological evaluation

Haspin is a mitotic protein kinase required for proper cell division by modulating Aurora B kinase localisation and activity as well as histone phosphorylation. Here a series of imidazopyridazines based on the CHR-6494 and Structure Activity Relationship was established. An assessment of the inhibitory activity of the lead structures on human Haspin and several other protein kinases is presented. The lead structure was rapidly optimised using a combination of crystal structures and effective docking models, with the best inhibitors exhibiting potent inhibitory activity on Haspin with IC₅₀ between 6 and 100 nM in vitro. The developed inhibitors displayed anti-proliferative properties against various human cancer cell lines in 2D and spheroid cultures and significantly inhibited the migration ability of osteosarcoma U-2 OS cells. Notably, we show that our lead compounds are powerful Haspin inhibitors in human cells, and did not block G2/M cell cycle transition due to improved selectivity against CDK1/CyclinB.

Five decades of low intensity and low survival: adapting intensified regimens to cure pediatric Burkitt lymphoma in Africa

Long-term cure of childhood Burkitt lymphoma (BL) in sub-Saharan Africa after treatment with single-agent cyclophosphamide has been documented for more than half of a century. Contemporary cure rates for the highest-risk patients with BL in high-income countries exceed 90% using intensive multiagent chemotherapy. By contrast, the majority of African children with BL still die. Data spanning 5 decades in Africa have repeatedly shown that the children most likely to achieve cure with limited cyclophosphamide regimens are those with lower-stage disease isolated to the jaw. Attempts to intensify the cyclophosphamide monotherapy backbone with the addition of vincristine, low-dose methotrexate, prednisone, doxorubicin, and/or low-dose cytarabine have not yielded significant improvement. High-dose methotrexate is a critical component in the treatment of childhood BL worldwide. Although initial efforts in Africa to incorporate high-dose methotrexate resulted in high treatment-related mortality, more recent collaborative experiences from North and West Africa, as well as Central America, demonstrate that it can be administered safely and effectively, despite limitations in supportive care resources. Recognizing the unacceptable disparity in curative outcomes for BL between the United States/Europe and equatorial Africa, there is a critical need to safely adapt contemporary treatment regimens to optimize curative outcomes amid the resource limitations in regions where BL is endemic. Here, we critically review reports of BL treatment outcomes from low- and middle-income countries, in addition to data from high-income countries that predated modern intensified regimens, to identify potential strategies to improve the therapeutic approach for children suffering from BL in sub-Saharan Africa.

Transcriptome integration analysis and specific diagnosis model construction for Hodgkin's lymphoma, diffuse large B-cell lymphoma, and mantle cell lymphoma

Transcriptome differences between Hodgkin's lymphoma (HL), diffuse large B-cell lymphoma (DLBCL), and mantle cell lymphoma (MCL), which are all derived from B cell, remained unclear. This study aimed to construct lymphoma-specific diagnostic models by screening lymphoma marker genes. Transcriptome data of HL, DLBCL, and MCL were obtained from public databases. Lymphoma marker genes were screened by comparing cases and controls as well as the intergroup differences among lymphomas. A total of 9 HL marker genes, 7 DLBCL marker genes, and 4 MCL marker genes were screened in this study. Most HL marker genes were upregulated, whereas DLBCL and MCL marker genes were downregulated compared to controls. The optimal HL-specific diagnostic model contains one marker gene (MYH2) with an AUC of 0.901. The optimal DLBCL-specific diagnostic model contains 7 marker genes (LIPF, CCDC144B, PRO2964, PHF1, SFTPA2, NTS, and HP) with an AUC of 0.951. The optimal MCL-specific diagnostic model contains 3 marker genes (IGLV3-19, IGKV4-1, and PRB3) with an AUC of 0.843. The present study reveals the transcriptome data-based differences between HL, DLBCL, and MCL, when combined with other clinical markers, may help the clinical diagnosis and prognosis.

Karonudib has potent anti-tumor effects in preclinical models of B-cell lymphoma

Chemo-immunotherapy has improved survival in B-cell lymphoma patients, but refractory/relapsed diseases still represent a major challenge, urging for development of new therapeutics. Karonudib (TH1579) was developed to inhibit MTH1, an enzyme preventing oxidized dNTP-incorporation in DNA. MTH1 is highly upregulated in tumor biopsies from patients with diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma, hence confirming a rationale for targeting MTH1. Here, we tested the efficacy of karonudib in vitro and in preclinical B-cell lymphoma models. Using a range of B-cell lymphoma cell lines, karonudib strongly reduced viability at concentrations well tolerated by activated normal B cells. In B-cell lymphoma cells, karonudib increased incorporation of 8-oxo-dGTP into DNA, and prominently induced prometaphase arrest and apoptosis due to failure in spindle assembly. MTH1 knockout cell lines were less sensitive to karonudib-induced apoptosis, but were displaying cell cycle arrest phenotype similar to the wild type cells, indicating a dual inhibitory role of the drug. Karonudib was highly potent as single agent in two different lymphoma xenograft models, including an ABC DLBCL patient derived xenograft, leading to prolonged survival and fully controlled tumor growth. Together, our preclinical findings provide a rationale for further clinical testing of karonudib in B-cell lymphoma.

New developments in non-Hodgkin lymphoid malignancies

The revised fourth edition of the World Health Organization (WHO) Classification of Tumours of Haematopoietic and Lymphoid Tissues (2017) reflects significant advances in understanding the biology, genetic basis and behaviour of haematopoietic neoplasms. This review focuses on some of the major changes in B-cell and T-cell non-Hodgkin lymphomas in the 2017 WHO and includes more recent updates. The 2017 WHO saw a shift towards conservatism in the classification of precursor lesions of small B-cell lymphomas such as monoclonal B-cell lymphocytosis, in situ follicular and in situ mantle cell neoplasms. With more widespread use of next generation sequencing (NGS), special entities within follicular lymphoma and mantle cell lymphoma were recognised with recurrent genetic aberrations and unique clinicopathological features. The diagnostic workup of lymphoplasmacytic lymphoma and hairy cell leukaemia has been refined with the discovery of MYD88 L265P and BRAF V600E mutations, respectively, in these entities. Recommendations in the immunohistochemical evaluation of diffuse large B-cell lymphoma include determining cell of origin and expression of MYC and BCL2, so called 'double-expressor' phenotype. EBV-positive large B-cell lymphoma of the elderly has been renamed to recognise its occurrence amongst a wider age group. EBV-positive mucocutaneous ulcer is a newly recognised entity with indolent clinical behaviour that occurs in the setting of immunosuppression. Two lymphomas with recurrent genetic aberrations are newly included provisional entities: Burkitt-like lymphoma with 11q aberration and large B-cell lymphoma with IRF4 rearrangement. Aggressive B-cell lymphomas with MYC, BCL2 and/or BCL6 rearrangements, so called 'double-hit/triple-hit' lymphomas are now a distinct entity. Much progress has been made in understanding intestinal T-cell lymphomas. Enteropathy-associated T-cell lymphoma, type II, is now known to not be associated with coeliac disease and is hence renamed monomorphic epitheliotropic T-cell lymphoma. An indolent clonal T-cell lymphoproliferative disorder of the GI tract is a newly included provisional entity. Angioimmunoblastic T-cell lymphoma and nodal T-cell lymphomas with T-follicular helper phenotype are included in a single broad category, emphasising their shared genetic and phenotypic features. Anaplastic large cell lymphoma, ALK- is upgraded to a definitive entity with subsets carrying recurrent rearrangements in DUSP22 or TP63. Breast implant-associated anaplastic large cell lymphoma is a new provisional entity with indolent behaviour. Finally, cutaneous T-cell proliferations include a new provisional entity, primary cutaneous acral CD8-positive T-cell lymphoma, and reclassification of primary small/medium CD4-positive T-cell lymphoma as lymphoproliferative disorder.

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

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

Atypical protein kinase C is essential for embryonic vascular development in mice

The atypical PKC (aPKC) subfamily constitutes PKCζ and PKCλ in mice, and both aPKC isoforms have been proposed to be involved in regulating various endothelial cell (EC) functions. However, the physiological function of aPKC in ECs during embryonic development has not been well understood. To address this question, we utilized Tie2-Cre to delete PKCλ alone (PKCλ-SKO) or both PKCλ and PKCζ (DKO) in ECs, and found that all DKO mice died at around the embryonic day 11.5 (E11.5), whereas a small proportion of PKCλ-SKO mice survived till birth. PKCλ-SKO embryos also exhibited less phenotypic severity than DKO embryos at E10.5 and E11.5, suggesting a potential compensatory role of PKCζ for PKCλ in embryonic ECs. We then focused on DKO embryos and investigated the effects of aPKC deficiency on embryonic vascular development. At E9.5, deletion of both aPKC isoforms reduced the diameters of vitelline artery and vein, and decreased branching from both vitelline vessels in yolk sac. Ablation of both aPKC isoforms also disrupted embryonic angiogenesis in head and trunk at the same stage, increasing apoptosis of both ECs and non-ECs. Taken together, our results demonstrated that aPKC in ECs plays an essential role in regulating cell apoptosis, angiogenesis, and embryonic survival.

Germinal Center Cells Turning to the Dark Side: Neoplasms of B Cells, Follicular Helper T Cells, and Follicular Dendritic Cells

Gaining knowledge of the neoplastic side of the three main cells—B cells, Follicular Helper T (Tfh) cells, and follicular dendritic cells (FDCs) —involved in the germinal center (GC) reaction can shed light toward further understanding the microuniverse that is the GC, opening the possibility of better treatments. This paper gives a review of the more complex underlying mechanisms involved in the malignant transformations that take place in the GC. Whilst our understanding of the biology of the GC-related B cell lymphomas has increased—this is not reviewed in detail here—the dark side involving neoplasms of Tfh cells and FDCs are poorly studied, in great part, due to their low incidence. The aggressive behavior of Tfh lymphomas and the metastatic potential of FDCs sarcomas make them clinically relevant, merit further attention and are the main focus of this review. Tfh cells and FDCs malignancies can often be misdiagnosed. The better understanding of these entities linked to their molecular and genetic characterization will lead to prediction of high-risk patients, better diagnosis, prognosis, and treatments based on molecular profiles.

Prognostic value of HLA-I homozygosity in patients with non-small cell lung cancer treated with single agent immunotherapy

BACKGROUND

We aimed to assess the impact of genomic human leukocyte antigen (HLA)-I/II homozygosity on the survival benefit of patients with unresectable locally advanced, metastatic non-small lung cancer treated by single-agent programmed cell death protein-1/programmed death ligand 1 (PD1/PDL1) inhibitors.

METHODS

We collected blood from 170 patients with advanced lung cancer treated with immunotherapy at two major oncology centers in Western Australia. Genomic DNA was extracted from white blood cells and used for HLA-I/II high-resolution typing. HLA-I/II homozygosity was tested for association with survival outcomes. Univariable and multivariable Cox regression models were constructed to determine whether HLA homozygosity was an independent prognostic factor affecting Overall Survival (OS) and Progression Free Survival (PFS). We also investigated the association between individual HLA-A and -B supertypes with OS.

RESULTS

Homozygosity at HLA-I loci, but not HLA-II, was significantly associated with shorter OS (HR=2.17, 95% CI 1.13 to 4.17, p=0.02) in both univariable and multivariable analysis. The effect of HLA-I homozygosity in OS was particularly relevant for patients with tumors expressing PDL1 ≥50% (HR=3.93, 95% CI 1.30 to 11.85, p<0.001). The adverse effect of HLA-I homozygosity on PFS was only apparent after controlling for interactions between PDL1 status and HLA-I genotype (HR=2.21, 95% CI 1.04 to 4.70, p=0.038). The presence of HLA-A02 supertype was the only HLA-I supertype to be associated with improved OS (HR=0.56, 95% CI 0.34 to 0.93, p=0.023).

CONCLUSION

Our results suggest that homozygosity at ≥1 HLA-I loci is associated with short OS and PFS in patients with advanced non-small cell lung cancer with PDL1 ≥50% treated with single-agent immunotherapy. Carriers of HLA-A02 supertype reported better survival outcomes in this cohort of patients.