Characteristic Expression Patterns of TCL1, CD38, and CD44 Identify Aggressive Lymphomas Harboring a MYC Translocation

Combining CD38 antibody with CD47 blockade is a promising strategy for treating hematologic malignancies expressing CD38

Background

CD38 and CD47 are expressed in many hematologic malignancies, including multiple myeloma (MM), B-cell non-Hodgkin lymphoma (NHL), B-cell acute lymphoblastic leukemia (ALL), and B-cell chronic lymphocytic leukemia (CLL). Here, we evaluated the antitumor activities of CD38/CD47 bispecific antibodies (BsAbs).

Methods

Five suitable anti-CD38 antibodies for co-targeting CD47 and CD38 BsAb were developed using a 2 + 2 "mAb-trap" platform. The activity characteristics of the CD38/CD47 BsAbs were evaluated using in vitro and in vivo systems.

Results

Using hybridoma screening technology, we obtained nine suitable anti-CD38 antibodies. All anti-CD38 antibodies bind to CD38+ tumor cells and kill tumor cells via antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). Five anti-CD38 antibodies (4A8, 12C10, 26B4, 35G5, and 65A7) were selected for designing CD38/CD47 BsAbs (IMM5605) using a "mAb-trap" platform. BsAbs had higher affinity and binding activity to the CD38 target than those to the CD47 target, decreasing the potential on-target potential and off-tumor effects. The CD38/CD47 BsAbs did not bind to RBCs and did not induce RBC agglutination; thus, BsAbs had much lower blood toxicity. The CD38/CD47 BsAbs had a greater ability to block the CD47/SIRPα signal in CD38+/CD47+ tumor cells than IMM01 (SIRPα Fc fusion protein). Through Fc domain engineering, CD38/CD47 BsAbs were shown to kill tumors more effectively by inducing ADCC and ADCP. IMM5605-26B4 had the strongest inhibitory effect on cellular CD38 enzymatic activity. IMM5605-12C10 had the strongest ability to directly induce the apoptosis of tumor cells. The anti-CD38 antibody 26B4 combined with the SIRPα-Fc fusion proteins showed strong antitumor effects, which were better than any of the mono-therapeutic agents used alone in the NCI-H929 cell xenograft model. The CD38/CD47 BsAbs exhibited strong antitumor effects; specifically, IMM5605-12C10 efficiently eradicated all established tumors in all mice.

Conclusion

A panel of BsAbs targeting CD38 and CD47 developed based on the "mAb-tarp" platform showed potent tumor-killing ability in vitro and in vivo. As BsAbs had lower affinity for binding to CD47, higher affinity for binding to CD38, no affinity for binding to RBCs, and did not induce RBC agglutination, we concluded that CD38/CD47 BsAbs are safe and have a satisfactory tolerability profile.

Preclinical anti-tumour activity of HexaBody-CD38, a next-generation CD38 antibody with superior complement-dependent cytotoxic activity

BACKGROUND

HexaBody®-CD38 (GEN3014) is a hexamerization-enhanced human IgG1 that binds CD38 with high affinity. The E430G mutation in its Fc domain facilitates the natural process of antibody hexamer formation upon binding to the cell surface, resulting in increased binding of C1q and potentiated complement-dependent cytotoxicity (CDC).

METHODS

Co-crystallization studies were performed to identify the binding interface of HexaBody-CD38 and CD38. HexaBody-CD38-induced CDC, antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), trogocytosis, and apoptosis were assessed using flow cytometry assays using tumour cell lines, and MM patient samples (CDC). CD38 enzymatic activity was measured using fluorescence spectroscopy. Anti-tumour activity of HexaBody-CD38 was assessed in patient-derived xenograft mouse models in vivo.

FINDINGS

HexaBody-CD38 binds a unique epitope on CD38 and induced potent CDC in multiple myeloma (MM), acute myeloid leukaemia (AML), and B-cell non-Hodgkin lymphoma (B-NHL) cells. Anti-tumour activity was confirmed in patient-derived xenograft models in vivo. Sensitivity to HexaBody-CD38 correlated with CD38 expression level and was inversely correlated with expression of complement regulatory proteins. Compared to daratumumab, HexaBody-CD38 showed enhanced CDC in cell lines with lower levels of CD38 expression, without increasing lysis of healthy leukocytes. More effective CDC was also confirmed in primary MM cells. Furthermore, HexaBody-CD38 efficiently induced ADCC, ADCP, trogocytosis, and apoptosis after Fc-crosslinking. Moreover, HexaBody-CD38 strongly inhibited CD38 cyclase activity, which is hypothesized to relieve immune suppression in the tumour microenvironment.

INTERPRETATION

Based on these preclinical studies, a clinical trial was initiated to assess the clinical safety of HexaBody-CD38 in patients with MM.

FUNDING

Genmab.

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.

Anti CD38 monoclonal antibodies for multiple myeloma treatment

CD38 is a transmembrane glycoprotein with ectoenzymatic activity and is highly and uniformly expressed on multiple myeloma (MM) cells. CD38 is expressed also at relatively low levels on normal lymphoid and myeloid cells, and in some tissues of non-hematopoietic origin. The specificity of this target has increased interest in new drugs and triggered the development of the CD38 monoclonal antibodies Daratumumab (fully human) and Isatuximab (chimeric). CD38 antibodies have pleiotropic mechanisms of action including Fc-dependent immune effector mechanisms, direct apoptotic activity, and immunomodulatory effects by the elimination of CD38+ immune-suppressor cells. Monoclonal antibody-based therapy has revolutionized MM therapy in the latest years increasing depth of response. This product review will focus on anti-CD38 monoclonal antibodies Daratumumab and Isatuximab efficacy, safety, pharmacokinetic and pharmacodynamic data from clinical trials.

Targeting CD38 in Neoplasms and Non-Cancer Diseases

Simple Summary

CD38 remains an interesting target for anticancer therapy. Its relatively high abundance in neoplasms and crucial impact on NAD+/cADPR metabolism and the activity of T cells allows for changing the immune response in autoimmune diseases, neoplasms, and finally the induction of cell death. Antibody-dependent cell cytotoxicity is responsible for cell death induced by targeting the tumor with anti-CD38 antibodies, such as daratumumab. A wide range of laboratory experiments and clinical trials show an especially promising role of anti-CD38 therapy against multiple myeloma, NK cell lymphomas, and CD19- B-cell malignancies. More studies are required to include more diseases in the therapeutic protocols involving the modulation of CD38 activity.

Abstract

CD38 is a myeloid antigen present both on the cell membrane and in the intracellular compartment of the cell. Its occurrence is often enhanced in cancer cells, thus making it a potential target in anticancer therapy. Daratumumab and isatuximab already received FDA approval, and novel agents such as MOR202, TAK079 and TNB-738 undergo clinical trials. Also, novel therapeutics such as SAR442085 aim to outrank the older antibodies against CD38. Multiple myeloma and immunoglobulin light-chain amyloidosis may be effectively treated with anti-CD38 immunotherapy. Its role in other hematological malignancies is also important concerning both diagnostic process and potential treatment in the future. Aside from the hematological malignancies, CD38 remains a potential target in gastrointestinal, neurological and pulmonary system disorders. Due to the strong interaction of CD38 with TCR and CD16 on T cells, it may also serve as the biomarker in transplant rejection in renal transplant patients. Besides, CD38 finds its role outside oncology in systemic lupus erythematosus and collagen-induced arthritis. CD38 plays an important role in viral infections, including AIDS and COVID-19. Most of the undergoing clinical trials focus on the use of anti-CD38 antibodies in the therapy of multiple myeloma, CD19- B-cell malignancies, and NK cell lymphomas. This review focuses on targeting CD38 in cancer and non-cancerous diseases using antibodies, cell-based therapies and CD38 inhibitors. We also provide a summary of current clinical trials targeting CD38.

A refined approach to the diagnosis of Burkitt lymphoma in a resource-poor setting

Burkitt lymphoma (BL) is among the most studied human malignancies. The distinction of BL from other aggressive B-cell lymphomas is important for providing optimal oncological care. In the revised 4^th edition of the World Health Organization (WHO) classification, BL is defined as "a highly aggressive but curable lymphoma that often presents in extranodal sites or as an acute leukemia. It is composed of monomorphic medium-sized B-cells with basophilic cytoplasm and numerous mitotic figures, usually with a demonstrable MYC gene translocation to an IG locus. The frequency of EBV (Epstein Barr virus) infection varies according to the epidemiological subtype of BL. No single parameter, such as morphologic, genetic analysis or immunophenotyping can be used as the gold standard for diagnosis of BL; a combination of several diagnostic techniques is necessary."

The Modes of Dysregulation of the Proto-Oncogene T-Cell Leukemia/Lymphoma 1A

Simple Summary

T-cell leukemia/lymphoma 1A (TCL1A) is a proto-oncogene that is mainly expressed in embryonic and fetal tissues, as well as in some lymphatic cells. It is frequently overexpressed in a variety of T- and B-cell lymphomas and in some solid tumors. In chronic lymphocytic leukemia and in T-prolymphocytic leukemia, TCL1A has been implicated in the pathogenesis of these conditions, and high-level TCL1A expression correlates with more aggressive disease characteristics and poorer patient survival. Despite the modes of TCL1A (dys)regulation still being incompletely understood, there are recent advances in understanding its (post)transcriptional regulation. This review summarizes the current concepts of TCL1A’s multi-faceted modes of regulation. Understanding how TCL1A is deregulated and how this can lead to tumor initiation and sustenance can help in future approaches to interfere in its oncogenic actions.

Abstract

Incomplete biological concepts in lymphoid neoplasms still dictate to a large extent the limited availability of efficient targeted treatments, which entertains the mostly unsatisfactory clinical outcomes. Aberrant expression of the embryonal and lymphatic TCL1 family of oncogenes, i.e., the paradigmatic TCL1A, but also TML1 or MTCP1, is causally implicated in T- and B-lymphocyte transformation. TCL1A also carries prognostic information in these particular T-cell and B-cell tumors. More recently, the TCL1A oncogene has been observed also in epithelial tumors as part of oncofetal stemness signatures. Although the concepts on the modes of TCL1A dysregulation in lymphatic neoplasms and solid tumors are still incomplete, there are recent advances in defining the mechanisms of its (de)regulation. This review presents a comprehensive overview of TCL1A expression in tumors and the current understanding of its (dys)regulation via genomic aberrations, epigenetic modifications, or deregulation of TCL1A-targeting micro RNAs. We also summarize triggers that act through such transcriptional and translational regulation, i.e., altered signals by the tumor microenvironment. A refined mechanistic understanding of these modes of dysregulations together with improved concepts of TCL1A-associated malignant transformation can benefit future approaches to specifically interfere in TCL1A-initiated or -driven tumorigenesis.

Additional flow cytometric studies for differential diagnosis between Burkitt lymphoma/leukemia and B-cell precursor acute lymphoblastic leukemia

The differentiation between Burkitt lymphoma/leukemia (BL) and B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is sometimes complicated. Laboratory findings that favor BL (e.g., surface expression of μ heavy chain and/or one of the light chains of immunoglobulin, FAB L3 morphology of blasts, MYC gene rearrangements) are not always present simultaneously. Our previous work demonstrated that BL differed from Ig(+) BCP-ALL by expression of Ig and other surface markers. In the current study, we have evaluated additional flow cytometric markers for reliable differentiation between BL and BCP-ALL. Among three studied surface antigens (CD44, CD38, CD58), only CD58 demonstrated significantly higher expression in BL as compared to BCP-ALL. Moreover, BL cases were associated with an increased level of Ki-67 and a higher percentage of cells in the S-phase of cell cycle. These two features reflect an aggressive proliferative potential of BL. Thus, when BL is suspected and results of surface Ig evaluation are controversial, the flow cytometric analysis of CD58, Ki-67 and cell cycle could assist in the differential diagnosis.

Application of flow cytometry in the analysis of lymphoid disease in the lung and pleural space

Various types of lymphoid neoplasms can occur in the lung. Lung parenchyma, the pleura or the pleural cavity can be the primary site of a lymphoid neoplasm or can be involved secondarily as a result of systemic dissemination from a separate primary site. Recognition of pulmonary lymphoid neoplasms (PLN) has increased secondary to technological advances in the medical field. Multiparameter flow cytometry (FC) is a one of the diagnostic tools that serves an essential role in the detecting and categorizing PLNs. FC allows for rapid identification and immunophenotypic characterization of PLN. In this article, we discuss the role of FC in the diagnosis of the most commonly encountered PLNs as well as their basic clinicopathologic features. We briefly discuss the role of FC in identifying non-hematolymphoid neoplasms in lung specimens as well.

Derlin-1 exhibits oncogenic activities and indicates an unfavorable prognosis in breast cancer

Derlin-1 is involved in the elimination of misfolded proteins and has been implicated in the progression of human cancers. However, its prognostic value and biological function in breast cancer remain unknown. Here, we show that Derlin-1 is overexpressed in breast cancer and exhibits oncogenic activities via interaction with UBE2C. Increased expression of Derlin-1 is correlated with lymph node metastasis, advanced clinical stage, and unfavorable overall survival in two cohorts containing over 1,000 patients. Multivariate analyses by the Cox regression model suggest Derlin-1 is an independent factor for poor prognosis. In vitro experiments demonstrate that Derlin-1 expression is transcriptionally upregulated by c-Myc. Ectopic expression of Derlin-1 promotes breast cancer cell proliferation and migration, whereas the knockdown of Derlin-1 results in the opposite phenotypes. Mechanistically, Derlin-1 directly binds to UBE2C to increase the phosphorylation of AKT and ERK. The treatment of UBE2C siRNA markedly attenuates Derlin-1-mediated cell growth and migration. Collectively, our data suggest Derlin-1 is a potential prognostic factor and functions as an oncogene in breast cancer.

A combination of LMO2 negative and CD38 positive is useful for the diagnosis of Burkitt lymphoma

Background

To evaluate the clinical utility of LIM Domain Only 2 (LMO2) negative and CD38 positive in diagnosis of Burkitt lymphoma (BL).

Methods

LMO2 and CD38 expression determined by immunohistochemistry in 75 BL, 12 High-grade B-cell lymphoma, NOS (HGBL,NOS) and 3 Burkitt-like lymphomas with the 11q aberration.

Results

The sensitivity and specificity of LMO2 negative for detecting BL were 98.67 and 100%, respectively; those of CD38 positive were 98.67 and 66.67%, respectively. The sensitivity and specificity of a combination of both for detecting BL were 97.33 and 100%, respectively. In our study, the combined LMO2 negative and CD38 positive results had a higher area under the curve than either LMO2 negative or CD38 positive alone.

Conclusions

A combination of LMO2 negative and CD38 positive is useful for the diagnosis of Burkitt lymphoma.

Low rate of spleen involvement in sporadic Burkitt lymphoma at staging on PET-CT

BACKGROUND

Burkitt lymphoma is a highly aggressive B cell non-Hodgkin lymphoma. Cross-sectional imaging techniques that are used to detect liver and spleen involvement by lymphoma have high rates of false negative and false positive findings, and as such may reduce the accuracy of staging.

PURPOSE

This retrospective study evaluated the use of FDG PET-CT in determining splenic involvement at staging, in a relatively large cohort of adult patients with the sporadic form of Burkitt lymphoma (SBL).

PATIENTS AND METHODS

All adult patients who underwent FDG PET-CT for staging of SBL at one medical center during 2005-2014 were enrolled for this retrospective study.

RESULTS

Data were analyzed of 20 patients, with median age 49 years; 17 were male. PET-CT revealed highly intense FDG uptake, mean SUV max 11.4 ± 7.49 (range 4.3-38) in various tissues. None of the 20 patients had either focal or diffuse increased uptake of FDG in the spleen parenchyma. In 2 patients, there were highly FDG-avid soft tissue masses adjacent to the spleen, both in the context of direct peritoneal disease extension.

CONCLUSION

The spleen is rarely involved in SBL at the time of staging, according to PET-CT, except in cases with direct extension from adjacent peritoneal mass. The low rate of spleen involvement according to PET-CT may serve as a specific characteristic of SBL. Larger-scale clinical studies incorporating PET-CT scans in SBL are needed to confirm our observation.

A comprehensive flow-cytometry-based immunophenotypic characterization of Burkitt-like lymphoma with 11q aberration

We previously described a subset of MYC translocation-negative aggressive B-cell lymphomas resembling Burkitt lymphoma, characterized by proximal gains and distal losses in chromosome 11. In the 2016 WHO classification, these MYC-negative lymphomas were recognized as a new provisional entity, 'Burkitt-like lymphoma with 11q aberration'. Here we present an immunophenotype analysis of Burkitt-like lymphomas with 11q aberration. Cells were acquired by fine needle aspiration biopsy from 10 young adult patients, 80% of whom presented recurrence-free 5-year survival. Twenty-three MYC-positive Burkitt lymphomas, including three carrying both MYC rearrangement and 11q aberration, served as controls. By immunohistochemistry, all Burkitt-like lymphomas with 11q aberration were CD20+/CD10+/BCL6+/BCL2-/MUM1-/MYC+/EBV-, usually LMO2+/CD44-/CD43- and sometimes CD56+, and showed high proliferation rate. By flow cytometry, Burkitt-like lymphoma with 11q aberration immunophenotypically resembled MYC-positive Burkitt lymphoma, except for significantly (adjusted P<0.001) more frequent CD38^higher expression in Burkitt lymphoma (91% MYC-positive Burkitt lymphoma vs 10% Burkitt-like lymphoma with 11q aberration), more frequently diminished CD45 expression in Burkitt lymphoma (74% vs 10%), an exclusive CD16/CD56 and highly restricted CD8 expression in Burkitt-like lymphoma with 11q aberration (60% vs 0% and 40% vs 4%, respectively). We showed high diagnostic accuracy and effectiveness of flow cytometry in Burkitt lymphoma. CD16/CD56 expression without CD38^higher and the lack of CD16/CD56 with CD38^higher expression proves to be a reliable, fast, and cost-effective method for diagnosing 11q aberration and MYC rearrangements in CD10(+) aggressive lymphomas, respectively. In addition, we confirmed a pattern of an inverted duplication with telomeric loss of 11q, as a recurrent 11q abnormality, but one case presented alternative changes, possibly resulting in an equivalent molecular effect. Our findings reveal similarities along with subtle but essential differences in the immunophenotype of Burkitt-like lymphoma with 11q aberration and MYC-positive Burkitt lymphoma, important for the differential diagnosis, but also for understanding the pathogenesis of Burkitt-like lymphoma with 11q aberration.

The importance of CD39, CD43, CD81, and CD95 expression for differentiating B cell lymphoma by flow cytometry

BACKGROUND

B cell lymphomas' (BCL) current diagnosis is usually based on a combination of morphology, immunophenotype, recurrent cytogenetic aberration and clinical features. However, even with these diagnostic tools, a definitive diagnosis can be difficult to achieve. Therefore, the aim of this study was to assess the profile of CD39, CD43, CD81, and CD95 expressions in diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), and Burkitt lymphoma (BL) cases.

METHODS

To address this issue, we investigated the expression of CD39, CD43, CD81, and CD95 by eight-color flow cytometry in retrospective cases from 2014 to 2016.

RESULTS

The study included 27 adult patients diagnosed with DLBCL, FL, and BL during the study period. Four patients were diagnosed with germinal center B cell-like DLBCL (GCB DLBCL), seven with non-GCB DLBCL, nine with FL, and seven with BL. CD39 seems to be especially relevant to differentiate non-GCB DLBCL from BL and from FL. BL showed stronger expression of CD43 when compared to FL and GCB DLBCL. Moreover, CD43 may help to distinguish non-GCB DLBCL from GCB DLBCL. CD81 expression was much stronger in BL when compared to the other three groups of patients. Lastly, CD95 may also help to distinguish BL from the other subtypes, as BL cells expressed this antigen at low levels.

CONCLUSIONS

In combination, CD39, CD43, CD81, and CD95 expressions appear to be helpful to distinguish CD10⁺ BCL, particularly BL. Phenotypic distinction between FL and GCB DLBCL remains challenging and requires further studies. © 2017 International Clinical Cytometry Society.

Validation of break-apart and fusion MYC probes using a digital fluorescence in situ hybridization capture and imaging system

INTRODUCTION

Detection of MYC translocations using fluorescence in situ hybridization (FISH) is important in the evaluation of lymphomas, in particular, Burkitt lymphoma and diffuse large B-cell lymphoma. Our aim was to validate a digital FISH capture and imaging system for the detection of MYC 8q24 translocations using LSI-MYC (a break-apart probe) and MYC 8;14 translocation using IGH-MYC (a fusion probe).

MATERIALS AND METHODS

LSI-MYC probe was evaluated using tissue sections from 35 patients. IGH-MYC probe was evaluated using tissue sections from forty patients. Sections were processed for FISH and analyzed using traditional methods. FISH slides were then analyzed using the GenASIs capture and analysis system.

RESULTS

Results for LSI-MYC had a high degree of correlation between traditional method of FISH analysis and digital FISH analysis. Results for IGH-MYC had a 100% concordance between traditional method of FISH analysis and digital FISH analysis.

CONCLUSION

Annotated whole slide images of H and E and FISH sections can be digitally aligned, so that areas of tumor within a section can be matched and evaluated with a greater degree of accuracy. Images can be archived permanently, providing a means for examining the results retrospectively. Digital FISH imaging of the MYC translocations provides a better diagnostic tool compared to traditional methods for evaluating lymphomas.

Clinical and biological significance of de novo CD5+ diffuse large B-cell lymphoma in Western countries

CD5 is a pan-T-cell surface marker and is rarely expressed in diffuse large B-cell lymphoma (DLBCL). Large-scale studies of de novo CD5+ DLBCL are lacking in Western countries. In this study by the DLBCL Rituximab-CHOP Consortium, CD5 was expressed in 5.5% of 879 DLBCL patients from Western countries. CD5+ DLBCL was associated with higher frequencies of >1 ECOG performance status, bone marrow involvement, central nervous system relapse, activated B-cell-like subtype, Bcl-2 overexpression, and STAT3 and NF-κB activation, whereas rarely expressed single-stranded DNA-binding protein 2 (SSBP2), CD30 or had MYC mutations. With standard R-CHOP chemotherapy, CD5+ DLBCL patients had significantly worse overall survival (median, 25.3 months vs. not reached, P< .0001) and progression-free survival (median, 21.3 vs. 85.8 months, P< .0001) than CD5- DLBCL patients, which was independent of Bcl-2, STAT3, NF-κB and the International Prognostic Index. Interestingly, SSBP2 expression abolished the prognostic significance of CD5 expression, suggesting a tumor-suppressor role of SSBP2 for CD5 signaling. Gene-expression profiling demonstrated that B-cell receptor signaling dysfunction and microenvironment alterations are the important mechanisms underlying the clinical impact of CD5 expression. This study shows the distinctive clinical and biological features of CD5+ DLBCL patients in Western countries and underscores important pathways with therapeutic implications.

Differentiating between Burkitt lymphoma and CD10+ diffuse large B-cell lymphoma: the role of commonly used flow cytometry cell markers and the application of a multiparameter scoring system

The goal of this study was to evaluate routine flow cytometric (FC) immunophenotypic markers in differentiating between Burkitt lymphoma (BL) and CD10+ diffuse large B-cell lymphoma (DLBCL). We performed retrospective analysis of FC data from 55 patients. We evaluated 9 FC parameters: forward and side scatter (FSC and SSC); mean fluorescent intensity (MFI) for CD20, CD10, CD38, CD79b, CD43, and CD71; and the percentage of neoplastic cells positive for CD71 (%CD71). The FSC; MFIs of CD10, CD43, CD79b, and CD71; and %CD71 cells were significantly different between BL and CD10+ DLBCL (P < .05; Student t test). A 5-point scoring system (FSC, %CD71, and MFIs of CD43, CD79b, and CD71) was devised, and 6 (60%) of 10 BLs scored 3 or greater and 1 (10%) of 10 CD10+ DLBCLs scored 3 (P = .04; χ(2)). Our findings indicate that routine FC parameters can aid in differentiating BL from CD10+ DLBCL.

Primary high-grade B-cell lymphoma of the breast with concurrent IGH-BCL2 and MYC-IGL translocations in an adolescent patient

BCL2 and MYC are oncogenes often deregulated in lymphomas. Concurrent IGH-BCL2 and MYC translocations result in a highly aggressive behavior of these tumors. Both primary breast lymphoma and lymphoma with concurrent BCL2-IGH and MYC translocations are rare and are primarily seen in adult patients. As a result of limited clinician experience and the condition's rarity, it poses a great challenge to pediatric pathologists and oncologists in terms of making an accurate diagnosis and choosing better treatment regimens. In this article, we report a case of an adolescent patient who presented with high-grade breast lymphoma with concurrent BCL2-IGH and MYC-IGL translocations, and we review the clinical, pathological, and genetic features; management strategies; and outcomes associated with this unusual neoplasm.

Diagnosis of Burkitt lymphoma using an algorithmic approach--applicable in both resource-poor and resource-rich countries

Distinguishing Burkitt lymphoma (BL) from B cell lymphoma, unclassifiable with features intermediate between diffuse large B-cell lymphoma (DLBCL) and BL (DLBCL/BL), and DLBCL is challenging. We propose an immunohistochemistry and fluorescent in situ hybridization (FISH) based scoring system that is employed in three phases - Phase 1 (morphology with CD10 and BCL2 immunostains), Phase 2 (CD38, CD44 and Ki-67 immunostains) and Phase 3 (FISH on paraffin sections for MYC, BCL2, BCL6 and immunoglobulin family genes). The system was evaluated on 252 aggressive B-cell lymphomas from Europe and from sub-Saharan Africa. Using the algorithm, we determined a specific diagnosis of BL or not-BL in 82%, 92% and 95% cases at Phases 1, 2 and 3, respectively. In 3·4% cases, the algorithm was not completely applicable due to technical reasons. Overall, this approach led to a specific diagnosis of BL in 122 cases and to a specific diagnosis of either DLBCL or DLBCL/BL in 94% of cases that were not diagnosed as BL. We also evaluated the scoring system on 27 cases of BL confirmed on gene expression/microRNA expression profiling. Phase 1 of our scoring system led to a diagnosis of BL in 100% of these cases.

CD44 in hematological neoplasias

The CD44 protein family spans a large group of transmembrane glycoproteins acquired by alternative splicing and post-translational modifications. The great heterogeneity in molecular structure is reflected in its various important functions: CD44 mediates (1) interaction between cell and extracellular matrix, (2) signal submission, e.g., by acting as co-receptor for membrane-spanning receptor tyrosine kinases or by association with intracellular molecules initiating several signaling pathways, and (3) anchor function connecting to the cytoskeleton via the ezrin-radixin-moesin protein family. The expression pattern of the different CD44 isoforms display strong variations dependent on cell type, state of activation, and differentiation stage. In hematopoietic cells, CD44 mediates interaction of progenitor cells and bone marrow stroma during hematopoiesis, regulates maturation, and activation-induced cell death in T cells, influences neutrophil and macrophage migration as well as cytokine production, and participates in lymphocyte extravasation and migration. CD44 is involved in development and progress of hematological neoplasias by enhancement of apoptotic resistance, invasiveness, as well as regulation of bone marrow homing, and mobilization of leukemia-initiating cells into the peripheral blood. Thereby altered CD44 expression functions as marker for worse prognosis in most hematological malignancies. Additionally, CD44 expression levels can be used to distinguish between different hematological neoplasias and subtypes. Concerning new treatment strategies, CD44 displays promising potential either by direct targeting of CD44 expressed on the malignant cells or reversing an acquired resistance to primary treatment mediated through altered CD44 expression. The former can be achieved by antibody or hyaluronan-based immunotherapy.

Diagnosis of Burkitt Lymphoma and Related High-Grade B-Cell Neoplasms

Burkitt lymphoma (BL) is an aggressive B-cell neoplasm with an extremely short doubling time that mainly affects children and young adults. Despite having several characteristic features, none is entirely specific for BL and the differential diagnosis may include diffuse large B-cell lymphoma (DLBCL), B lymphoblastic leukemia/lymphoma, and B-cell lymphoma unclassifiable with features intermediate between DLBCL and BL. We outline a practical approach to establish a diagnosis of BL and distinguish it from other high-grade B-cell malignancies. We pay particular attention to B-cell lymphomas with features intermediate between DLBCL and BL, a new diagnostic category in the 2008 World Health Organization classification system that provides a framework for categorizing challenging cases not meeting diagnostic criteria for either "classic" BL or DLBCL.

The pre-B-cell receptor associated protein VpreB3 is a useful diagnostic marker for identifying c-MYC translocated lymphomas

BACKGROUND

During B-cell development, precursor B cells transiently express the pre-B-cell receptor composed of μ heavy chain complexed with VpreB and λ5 surrogate light chain polypeptides. Recent profiling studies unexpectedly revealed abundant transcripts of one member of the VpreB family, VpreB3, in a subset of mature B cells and Burkitt lymphoma.

DESIGN AND METHODS

Here we used a novel antibody to investigate the normal expression pattern of VpreB3 protein in human hematopoietic and lymphoid tissues, and to determine whether VpreB3 could serve as a useful diagnostic biomarker for select B-cell lymphomas.

RESULTS

We found that VpreB3 protein is normally expressed by precursor B cells in bone marrow and by a subset of normal germinal center B cells in secondary lymphoid organs. Among lymphoid malignancies, we found an association between VpreB3 expression and B-cell tumors with c-MYC abnormalities. VpreB3 was highly expressed in all cases of Burkitt lymphoma, whether of endemic or sporadic origin (44/44 cases, 100%), all cases of B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma (5/5 cases, 100%), and the majority of diffuse large B-cell lymphomas harboring a c-MYC translocation (15/18 cases, 83%). The expression of VpreB3 in diffuse large B-cell lymphomas without a c-MYC translocation was associated with c-MYC polysomy in 25/75 cases (33%) but only rarely observed in diffuse large B-cell lymphomas lacking a c-MYC abnormality (9/98 cases, 9%).

CONCLUSIONS

We conclude that for B-cell tumors with features suggesting a possible c-MYC translocation, such as intermediate to large cell size and high proliferation rate, the presence of VpreB3 should prompt subsequent confirmatory genetic testing, whereas the absence of VpreB3 is virtually always associated with wild-type c-MYC alleles.

The basis and rational use of molecular genetic testing in mature B-cell lymphomas

An increasing number of neoplasms are associated with variably specific genetic abnormalities. This is best exemplified by hematological malignancies, in which there is a growing list of entities that are defined by their genetic lesion(s); this is not (yet) the case in mature B-cell lymphomas. However, enhanced insights into the pathogenesis of this large and diverse group of lymphomas have emerged with the ongoing unraveling of a plethora of fascinating genetic abnormalities. The purpose of this review is to synthesize well-recognized data and nascent discoveries in our understanding of the genetic basis of a spectrum of mature B-cell lymphomas, and how this may be applied to contemporary clinical practice. Despite the explosion of new and exciting knowledge in this arena, with the potential for enhanced diagnostic and prognostic strategies, it is essential to remain cognizant of the limitations (and complexity) of genetic investigations, so that assays can be developed and used both judiciously and rationally.

"Double-Hit" mature B-cell lymphomas show a common immunophenotype by flow cytometry that includes decreased CD20 expression

Lymphomas with 2 translocations involving c-MYC and BCL2 or BCL6 are a subset of biologically aggressive mature B-cell lymphomas now frequently categorized under the entity of B-cell lymphoma, unclassifiable, with features intermediate between Burkitt lymphoma and diffuse large B-cell lymphoma. We identified a cohort of these lymphomas in our databases and retrospectively reviewed corresponding in-house flow cytometric data to determine whether a common immunophenotype might be present. Herein we report on our findings on 10 lymphomas, each with translocations involving c-MYC and BCL2 or BCL6 and show that these cases frequently showed a common immunophenotype that includes decreased expression of CD20. Because these lymphomas often show aggressive biologic behavior and poor clinical outcome, recognition of this relatively common immunophenotype may be useful for identifying cases for confirmatory cytogenetic studies, as often, flow cytometry provides the first assessment of these clinical specimens.

Immunophenotypic variations of Burkitt lymphoma

Burkitt lymphoma (BL) exhibits a characteristic immunophenotype that is positive for pan-B-cell antigens and CD10 and expresses clonal surface immunoglobulins (SIgs). We evaluated 35 BLs and identified atypical immunophenotypes in 4 including SIg light chain negativity in 4, negativity for B-cell antigens in 2, lack of CD10 in 1, and CD4 expression in 1. All 4 cases showed morphologic features characteristic of BL, and all were confirmed by cytogenetic analysis. The 4 BL cases included 1 girl, 2 men with HIV/AIDS, and a third man with a history of heart transplantation. Two patients died shortly after diagnosis; the other 2 completed hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone with highly active antiretroviral therapy and achieved complete remission. Our study indicates that an unusual immunophenotype is not uncommon in BL. If the immunophenotype is interpreted in isolation, the diagnosis could be missed. Recognizing the variability of immunophenotype is essential for establishing an accurate diagnosis of BL.

Simple karyotype and bcl-6 expression predict a diagnosis of Burkitt lymphoma and better survival in IG-MYC rearranged high-grade B-cell lymphomas

Rearrangement of MYC with immunoglobulin genes is a hallmark of Burkitt lymphoma. However, this rearrangement is not entirely specific and is often accompanied by varying numbers of additional cytogenetic abnormalities. This study aimed to assess the impact of karyotypic complexity, in correlation with comprehensive immunophenotypic analyses on the diagnosis and clinical outcomes of 34 cases of MYC-IG rearranged lymphomas that included Burkitt lymphoma (twenty-two cases), diffuse large B-cell lymphoma (three cases), unclassifiable B-cell lymphoma with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma (six cases), and plasmablastic lymphoma (three cases). Additional cytogenetic abnormalities were observed in 26 of 34 cases (76%), including four cases (12%) that harbored dual translocations involving BCL-2 or BCl-6. Burkitt lymphoma cases had a significantly lower number of additional abnormalities (mean of 1.7), compared with unclassified B-cell lymphoma (3.3), diffuse large B-cell lymphoma (21.7), and plasmablastic lymphoma (6.7). Cases with simple karyotype (< or =2 additional abnormalities) were more likely to have a diagnosis of Burkitt lymphoma (89 versus 33% in patients with >2 additional abnormalities, P<0.01) and express bcl-6 (95 versus 47%, P<0.01). In addition, Burkitt lymphoma, bcl-6 expression, and simple karyotype were individual predictors of better overall survival. However, in multivariate analyses, only bcl-6 expression remained an independent predictor, although survival could be further stratified by karyotypic complexity in bcl-6(+) patients. We conclude that simple karyotype and bcl-6 expression suggest a diagnosis of Burkitt lymphoma and may portend better overall survival. These results may be very useful in the diagnosis and stratification of MYC-IG rearranged high-grade B-cell lymphomas.

Altered subcellular localization of c-Myc protein identifies aggressive B-cell lymphomas harboring a c-MYC translocation

Nearly 100% of Burkitt lymphomas (BLs) and 5% to 8% of diffuse large B-cell lymphomas (DLBCLs) harbor a balanced translocation involving c-MYC. Although characteristic morphologic and immunophenotypic features can identify BL in most cases, tumors with atypical features are often encountered in clinical practice. Furthermore, no morphologic or immunophenotypic finding can predict an underlying c-MYC translocation in DLBCL with certainty. Here we report on a novel monoclonal antibody recognizing the c-myc protein in formalin-fixed, paraffin-embedded tissue which we used to evaluate a spectrum of aggressive B-cell lymphomas by standard immunohistochemistry. Cases consisted of 17 BLs (15 cases with confirmed c-MYC translocation), 19 DLBCLs without a c-MYC translocation, 5 DLBCLs with a c-MYC translocation, and 2 B-cell lymphomas, unclassifiable, with features intermediate between DLBCL and BL (intermediate DBLCL/BL, one case with c-MYC translocation and one case without a c-MYC translocation). The intensity and subcellular localization of tumor-specific staining for c-myc protein was determined independently by 2 pathologists and in a blinded fashion for each case. We observed c-myc expression in the tumor cells of all cases regardless of c-MYC status. Among BLs, c-myc protein primarily localized to the nucleus of tumor cells in 15 of 17 cases (88%) and equally localized to the nucleus and cytoplasm of tumor cells in 2 of 17 cases (12%). In no case did c-myc protein primarily localize to the cytoplasm. In contrast, among DLBCLs lacking a c-MYC translocation the c-myc protein primarily localized to the cytoplasm of the tumor cells in 18 of 19 cases (95%) and equally localized to the nucleus and cytoplasm in the tumor cells in 1 of 19 cases (5%). In no case did c-myc protein primarily localize to the nucleus. Among DLBCLs with a c-MYC translocation and intermediate DBLCL/BLs, the c-myc protein primarily localized to the nucleus, or equally localized to the nucleus and cytoplasm of the tumor cells in 4 of 5 cases (80%) and 2 of 2 cases (100%), respectively. Taken together, we find that a primarily nuclear or mixed nuclear and cytoplasmic staining pattern for c-myc in an aggressive B-cell lymphoma is highly predictive of a c-MYC translocation (positive-predictive value=0.92, negative-predictive value=0.95, P<0.0001). We further show that the subcellular localization of c-myc can be determined with good interobserver agreement among pathologists (kappa statistic=0.90). Thus this novel immunohistochemsitry test is a useful tool for identifying aggressive B-cell lymphomas likely to harbor a c-MYC rearrangement and thus warrant genetic testing.

A novel flow cytometric antibody panel for distinguishing Burkitt lymphoma from CD10+ diffuse large B-cell lymphoma

Rapid and accurate differential diagnosis between Burkitt lymphoma (BL) and CD10+ diffuse large B-cell lymphoma (DLBCL) is imperative because their treatment differs. Recent studies have characterized several antigens differentially expressed in these 2 types of lymphoma. Our goal was to determine whether use of these markers would aid in the differential diagnosis of BL vs CD10+ DLBCL by flow cytometric immunophenotyping (FCI). Twenty-three cases of CD10+ B-cell lymphomas with available cryopreserved samples were identified (13 BL and 10 CD10+ DLBCL). Multiparameter FCI was performed using the following antibodies: CD18, CD20, CD43, CD44, and CD54 and isotype controls. Expression of CD44 and CD54 was detected at a significantly lower level in BL compared with CD10+ DLBCL (P = .001 and P = .01, respectively). There was not a significant difference in expression of CD18 and CD43. Our data show that expression of CD44 and CD54 differs significantly between BL and CD10+ DLBCL.

T-cell leukemia 1 expression in nodal Epstein-Barr virus-negative diffuse large B-cell lymphoma and primary mediastinal B-cell lymphoma

The physiologic expression of the product of the proto-oncogene TCL1 (T-cell leukemia 1) is primarily restricted to early embryonic cells. In nonneoplastic B cells, the expression of TCL1 is determined by the differentiation step with silencing at the germinal center stage. TCL1 protein is overexpressed in a wide variety of human diseases. It has been shown that TCL1 is a powerful B-cell oncogene, which has been implicated in the pathogenesis of various types of mature B-cell lymphomas. There is no comparative information in the literature addressing the expression of TCL1 in pediatric and adult nodal diffuse large B-cell lymphoma or primary mediastinal large B-cell lymphoma. We studied 55 cases of adult and pediatric diffuse large B-cell lymphoma and primary mediastinal large B-cell lymphoma to analyze the phenotypic profile of these lymphomas, including TCL1 expression, and its relationship with clinical outcome in different age groups. The cases were analyzed by immunohistochemistry for the expression of TCL1, CD10, BCL-2, BCL-6, and MUM1. We also evaluated c-MYC translocation by fluorescence in situ hybridization. TCL1 was observed in 11 cases, 5 pediatric and 6 adult cases, all but one diffuse large B-cell lymphoma. Pediatric cases showed a significant association between TCL1 expression, high proliferative index, and presence of c-MYC translocation. TCL1 positivity was predominantly found in germinal center phenotype diffuse large B-cell lymphoma. Overall survival was worse in adult TCL1-positive cases than pediatric ones. Primary mediastinal large B-cell lymphomas infrequently expressed TCL1 in both age groups.

Nodal diffuse large B-cell lymphomas in children and adolescents: immunohistochemical expression patterns and c-MYC translocation in relation to clinical outcome

Diffuse large B-cell lymphoma (DLBCL) is a very infrequent neoplasm in the pediatric age group; therefore there are very few studies on the immunophenotype or genetics of these cases. We studied a series of 16 patients with nodal DLBCL occurring in patients between 10 and 18 years of age. The cases were classified according to the 2008 World Health Organization classification criteria, with application of immunohistochemistry for the detection of CD10, BCL-6, and MUM1 proteins to divide the lymphomas into germinal center and nongerminal center types. In addition, TCL1, BCL-2 expression, and the Ki-67 proliferation index were evaluated by immunohistochemistry, and c-MYC and BCL2 translocations were evaluated by fluorescence in situ hybridization. All these parameters were correlated with clinical features and outcome. Our study revealed that centroblastic morphology and the germinal center type of DLBCL are more prevalent in these young patients (63%), with 37% containing a c-MYC translocation. Only 1 case showed a BCL2 translocation, reflecting a double-hit case with features intermediate between DLBCL and Burkitt lymphoma. We found a higher frequency of BCL-2 expression than previously reported, with no direct influence on the outcome of the disease in univariate or multivariate analysis. The expression of TCL1 has not been specifically studied in nodal pediatric DLBCL before; we found a 31% incidence of TCL1 expression. MUM1 expression was observed in 44% of the cases and these positive cases showed a significant negative impact on clinical outcome. TCL1 is directly and significantly associated with the presence of c-MYC and a high proliferative index. The germinal center and nongerminal center subtypes showed significant differences for both overall survival and disease-free interval. c-MYC translocation was found in 37% of patients, and had a favorable impact on clinical outcome. We conclude that nodal pediatric and adolescent DLBCL are mainly of the germinal center type, with a generally good outcome despite the frequent expression of BCL-2 and the presence of c-MYC translocation. TCL1 expression seems to be associated with a good clinical outcome, whereas MUM1 expression predicts a poor clinical outcome.

Plasmablastic lymphomas with MYC/IgH rearrangement: report of three cases and review of the literature

We report detailed clinicopathologic features of 3 cases of plasmablastic lymphoma (PBL) with MYC/IgH rearrangement, representing one third of PBL cases diagnosed at our institution. This study brings the total number of reported cases in the literature to 6. All patients were HIV+ with very low CD4 counts at diagnosis. The involved locations were mediastinum, anus, and bone marrow. Tumors exhibited predominantly immunoblastic/plasmablastic morphologic features and had a plasma cell-like immunophenotype. Bright CD38 expression by flow cytometry had a tendency to be more common in these cases compared with PBL without MYC rearrangement. All cases were positive for Epstein-Barr virus-encoded RNA but lacked human herpesvirus-8 latent nuclear antigen. The 2 patients with follow-up died within 3 months. These findings show that PBL is often associated with MYC/IgH rearrangements and that this finding may portend an aggressive clinical course, suggesting that cytogenetic studies should be routinely applied in cases of PBL.

Diffuse aggressive B-cell lymphomas

Diffuse aggressive B-cell lymphomas comprise a relatively common and increasingly diverse group of neoplasms. Newer modalities including gene expression profiling and an increasing panel of immunohistochemical markers have contributed to greater accuracy in defining these entities. Attention is paid not only to the neoplastic cells but also to the cellular and stromal milieu in which they proliferate. These distinctions may have therapeutic implications as well, with improved outcome related to newer and sometimes targeted therapies. At the same time there is increasing understanding of the overlap, which occurs in the grey zone between diffuse large B-cell lymphoma and Burkitt lymphoma as well as between diffuse large B-cell lymphoma and Hodgkin lymphoma. This review aims to provide practical insights in the correct identification and differential diagnosis of these lymphomas, with emphasis on the changes that have occurred with the publication of the 2008 World Health Organization updated classification.

TCL1A expression delineates biological and clinical variability in B-cell lymphoma

The assembly of a collection of gene-expression signatures of the major types of B-cell non-Hodgkin's lymphoma has identified increased T-cell leukemia/lymphoma 1A (TCL1) expression in multiple lymphoma types and cases, and has enabled the investigation of the functional and clinical importance of TCL1 expression. Specifically, Burkitt's lymphoma cases show a homogeneously strong expression of TCL1, whereas diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, chronic lymphocytic leukemia, nodal marginal zone lymphoma, and splenic marginal zone lymphoma display a striking variability in the intensity of TCL1 staining. This was validated in two independent series. A Gene-Set Enrichment Analysis of the genes correlated with TCL1A expression found that variation in the level of expression of TCL1A was significantly associated with some of the most important gene signatures recognizing B-cell lymphoma pathogenesis and heterogeneity, such as germinal center, B-cell receptor, NF-kappaB (and its target genes), death, MAP kinases, TNFR1, TOLL, and IL1R. Additionally, TCL1 expression was correlated with shorter time to treatment in chronic lymphocytic leukemia cases and shorter lymphoma-specific survival in mantle cell lymphoma series, thus indicating the clinical and biological significance of TCL1 expression, and suggesting TCL1A as a potential therapeutic target.

A prospective clinicopathologic study of dose-modified CODOX-M/IVAC in patients with sporadic Burkitt lymphoma defined using cytogenetic and immunophenotypic criteria (MRC/NCRI LY10 trial)

This prospective study aimed to develop reproducible diagnostic criteria for sporadic Burkitt lymphoma (BL), applicable to routine practice, and to evaluate the efficacy of dose-modified (dm) CODOX-M/IVAC in patients diagnosed using these criteria. The study was open to patients with an aggressive B-cell lymphoma with an MKI67 fraction approaching 100%. Immunophenotype and fluorescent in situ hybridization (FISH) were used to separate BL from other aggressive B-cell lymphomas. BL was characterized by the presence of a cMYC rearrangement as a sole cytogenetic abnormality occurring in patients with a germinal center phenotype with absence of BCL-2 expression and abnormal TP53 expression. A total of 128 patients were eligible for the study, of whom 58 were considered to have BL and 70 to have diffuse large B-cell lymphoma (DLBCL). There were 110 clinically fit patients who received dmCODOX-M (methotrexate, dose 3 g/m(2)) with or without IVAC according to risk group. The 2-year progression-free survival was 64% (95% confidence interval [CI] 51%-77%) for BL, 55% (95% CI 42%-66%) for DLBCL, 85% (95% CI 73%-97%) for low risk, and 49% (95% CI 38%-60%) for high-risk patients. The observed differences in outcome and other clinical features validate the proposed diagnostic criteria. Compared with the previous trial LY06 with full-dose methotrexate (6.7 g/m(2)), there was a reduction in toxicity with comparable outcomes. This study was registered at www.clinicaltrials.gov as NCT00040690.

Burkitt lymphoma in adults

This review will begin with a detail of the revision of the WHO classification, and pathological definitions of Burkitt lymphoma. Over the past several years, molecular understanding of Burkitt lymphoma has improved significantly. Using gene expression profiling, a genomic "signature" of Burkitt lymphoma may be identified, that has fidelity beyond c-myc expression, and the presence of the classical t(8;14). Then, evaluation and therapy of the adult patient with Burkitt lymphoma will be reviewed. Relatively few data exist on optimal therapy of the adult patient with Burkitt lymphoma. Principles of therapy should include high doses of alkylating agents, frequent administration of chemotherapy, and attention to central nervous system (CNS) prophylaxis with high doses of systemic chemotherapy, intrathecal therapy, or both. The outcome of adult patients with Burkitt lymphoma, particularly those over 40 years of age, is inferior to the outcome of younger patients, but may be improving over the past few years. Results from an international collaborative effort, which are helpful in evaluating results of Burkitt lymphoma therapy in adults, will be presented. HIV-associated Burkitt lymphoma, and elderly patients with Burkitt lymphoma, comprise special clinical situations that will be also covered in this review.