Clinical significance of bcl-2-MBR gene rearrangement and protein expression in diffuse large-cell non-Hodgkin's lymphoma: an analysis of 83 cases

Clinicopathological analysis of diffuse large B-cell lymphoma using molecular biomarkers: a retrospective analysis from 7 Hungarian centers

Background

The clinical and genetic heterogeneity of diffuse large B-cell lymphoma (DLBCL) presents distinct challenges in predicting response to therapy and overall prognosis. The main objective of this study was to assess the application of the immunohistochemistry- and interphase fluorescence in situ hybridization (FISH)-based molecular markers in the diagnosis of DLBCL and its prognostic value in patients treated with rituximab-based immunochemotherapy.

Methods

This is a multicenter, retrospective study, which analyzed data from 7 Hungarian hematology centers. Eligible patients were adults, had a histologically confirmed diagnosis of DLBCL, were treated with rituximab-based immunochemotherapy in the first line, and had available clinicopathological data including International Prognostic Index (IPI). On the specimens, immunohistochemistry and FISH methods were performed. Germinal center B-cell like (GCB) and non-GCB subtypes were classified by the Hans algorithm. Outcomes included overall survival (OS), event-free survival (EFS), and EFS at 2 years (EFS24). For survival analysis, we used Kaplan-Meier curves with the log-rank test and multivariate Cox regression.

Results

A total of 247 DLBCL cases were included. Cases were positive for MYC, BCL2, BCL6, and MUM1 expression in 52.1%, 66.2%, 72.6%, and 77.8%, respectively. BCL6 translocation, BCL2 gene copy number (GCN) gain, IGH::MYC translocation, MYC GCN gain, IGH::BCL2 translocation, and BCL6 GCN gain were detected in 21.4%, 14.1%, 7.3%, 1.8%, 7.3%, and 0.9%, respectively. At a median follow-up of 52 months, 140 patients (56.7%) had disease progression or relapse. The Kaplan-Meier estimate for EFS24 was 56.2% (CI: 50.4-62.8%). In univariate analysis, only IPI and BCL6 expression were significant predictors of both OS and EFS, whereas MUM1 predicted EFS only. In multivariate analysis, the IPI score was a significant independent negative, whereas MIB-1 and BCL6 protein expressions were significant independent positive predictors of both OS and EFS.

Conclusion

In our study, we found that only IPI, BCL6 protein expression and MIB-1 protein expression are independent predictors of survival outcomes in DLBCL. We did not find any difference in survival by GCB vs. non-GCB subtypes. These findings may improve prognostication in DLBCL and can contribute to designing further research in the area.

Co-Operativity between MYC and BCL-2 Pro-Survival Proteins in Cancer

B-Cell Lymphoma 2 (BCL-2), c-MYC and related proteins are arguably amongst the most widely studied in all of biology. Every year there are thousands of papers reporting on different aspects of their biochemistry, cellular and physiological mechanisms and functions. This plethora of literature can be attributed to both proteins playing essential roles in the normal functioning of a cell, and by extension a whole organism, but also due to their central role in disease, most notably, cancer. Many cancers arise due to genetic lesions resulting in deregulation of both proteins, and indeed the development and survival of tumours is often dependent on co-operativity between these protein families. In this review we will discuss the individual roles of both proteins in cancer, describe cancers where co-operativity between them has been well-characterised and finally, some strategies to target these proteins therapeutically.

Targeting BCL2 in Chronic Lymphocytic Leukemia and Other Hematologic Malignancies

Apoptosis, the process of programmed cell death, occurs normally during development and aging. Members of the B-cell lymphoma 2 (BCL2) family of proteins are central regulators of apoptosis, and resistance to apoptosis is one of the hallmarks of cancer. Targeting the apoptotic pathway via BCL2 inhibitors has been considered a promising treatment strategy in the past decade. Initial efforts with small molecule BH3 mimetics such as ABT-737 and ABT-263 (navitoclax) pioneered the development of the first-in-class Food and Drug Administration (FDA)-approved oral BCL2 inhibitor, venetoclax. Venetoclax was approved for the treatment of chronic lymphocytic leukemia and acute myeloid leukemia, and is now being studied in a number of hematologic malignancies. Several other inhibitors targeting different BCL2 family members are now in early stages of development.

Bendamustine plus Rituximab Versus R-CHOP as First-Line Treatment for Patients with Follicular Lymphoma Grade 3A: Evidence from a Multicenter, Retrospective Study

BACKGROUND

Rituximab plus bendamustine (R-B) has been demonstrated to improve outcomes and reduce toxicity compared with rituximab, cyclophosphamide, doxorubicin, and prednisone (R-CHOP) in follicular lymphoma (FL). Nevertheless, in clinical practice, many centers still prefer R-CHOP to R-B in patients with FL grade 3A (FL3A). Therefore, we retrospectively assessed patients with FL3A treated with either R-CHOP or R-B in five European cancer centers and compared their outcomes.

MATERIALS AND METHODS

We retrospectively assessed 132 patients affected by FL grade 3A treated with either R-B or R-CHOP in the first line and evaluated outcome and toxicity according to the type of treatment. This study included 101 patients who were a subgroup of a previously published cohort.

RESULTS

R-B was less toxic and achieved a similar percentage of complete remissions compared with R-CHOP (97% vs. 96%, p = .3). During follow-up, 10 (16%) patients relapsed after R-B and 29 (41%) after R-CHOP (p = .001), leading to a median progression-free survival (PFS) of 15 versus 11.7 years, respectively (p = .03). Furthermore, R-B overcame the negative prognostic impact of BCL2 expression (15 vs. 4.8 years; p = .001). However, median overall survival was similar between both groups (not reached for both; p = .8).

CONCLUSION

R-B as a first-line treatment of FL3A is better tolerated than R-CHOP and seems to induce more profound responses, leading to a significantly lower relapse rate and prolonged PFS. Therefore, R-B is a valid treatment option for FL grade 3A.

IMPLICATIONS FOR PRACTICE

Rituximab plus bendamustine (R-B) has shown to be less toxic and more effective than rituximab, cyclophosphamide, doxorubicin, and prednisone (R-CHOP) in follicular lymphoma grade 3A. Although both regimens can induce a complete remission in >95% of patients, relapses occur more frequently after R-CHOP than R-B, leading to a significantly longer progression-free survival in the latter. R-B is also able to overcome the impact of negative prognosticators, such as BCL2 expression. However, because of the indolent course of this disease and efficient salvage treatments, overall survival was similar in both treatment groups. Therefore, R-B is a valid treatment option in this patient setting.

Comprehensive Assessment and Classification of High-Grade B-cell Lymphomas

High-grade B-cell lymphomas (HGBCLs) are a heterogeneous group of neoplasms that include subsets of diffuse large B-cell lymphoma, Burkitt lymphoma, and lymphomas with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma. Morphologically indistinguishable HGBCLs may demonstrate variable clinical courses and responses to therapy. The morphologic evaluation and classification of these neoplasms must be followed by further genetic and immunophenotypic work-up. These additional diagnostic modalities lead to a comprehensive stratification of HGBCL that determines the prognosis and optimal therapy. This article reviews the well-established and emerging biomarkers that are most relevant to the clinical management of HGBCL.

Clinical Prognostic Biomarkers in Chronic Lymphocytic Leukemia and Diffuse Large B-Cell Lymphoma

Context

Diffuse large B-cell lymphoma and chronic lymphocytic leukemia are 2 of the most common B-cell lymphomas in adults. Both diffuse large B-cell lymphoma and chronic lymphocytic leukemia share heterogeneous outcomes, and the use of prognostic biomarkers to better stratify risk in these patients has now become commonplace.

Objective

To review chronic lymphocytic leukemia and diffuse large B-cell lymphoma biomarkers commonly used in the clinical laboratory, which can be divided into the following 3 main groups by testing methodology: chromosomal based (including fluorescence in situ hybridization and cytogenetics), expression based (including immunohistochemistry and flow cytometry), and DNA based (including gene sequencing for somatic mutations and IGVH mutational status).

Data Sources

Review of recent literature.

Conclusions

In chronic lymphocytic leukemia, important biomarkers include expression of CD38 and ZAP-70, IGVH mutational status, somatic mutations in TP53 and NOTCH1, and abnormalities in chromosomes 11, 12, 13q, and 17. In diffuse large B-cell lymphoma, important biomarkers include chromosomal rearrangement of BCL2, BCL6, and MYC and expression of CD5, BCL2, and CD43, as well as somatic mutations in TP53 and BCL6.

BCL2, BCL6, IGH, TP53, and MYC protein expression and gene rearrangements as prognostic markers in diffuse large B-cell lymphoma: a study of 44 Turkish patients

The purpose of this study was to determine the frequency of BCL2, BCL6, IGH, TP53, and MYC protein expression and rearrangements of the respective genes in diffuse large B-cell lymphoma (DLBCL) patients and to assess their prognostic values. Samples from 44 patients with DLBCL were evaluated using fluorescence in situ hybridization and immunohistochemical analyses. BCL6 was the most rearranged gene (63.6%), followed by MYC (31.8%), TP53 (22.7%), and BCL2 (18.2%). Multiple rearrangements were detected in 40.9% of the cases. BCL6 was the most expressed protein (78.6%), followed by TP53 (69.04%), BCL2 (59.5%) and MYC (14.3%). Expression of multiple proteins was detected in 67.4% of the cases. BCL2 (P = .003) expression had a significant negative influence on overall survival,whereas BCL6 (P = .014) expression had a significant positive influence. Our results with a different pattern of gene rearrangements and associated protein overexpression indicate the molecular genetic complexity of DLBCLs, which reflects the morphologic, biologic, and clinical heterogeneity of these lymphomas.

Patients with diffuse large B-cell lymphoma of germinal center origin with BCL2 translocations have poor outcome, irrespective of MYC status: a report from an International DLBCL rituximab-CHOP Consortium Program Study

Diffuse large B-cell lymphoma can be classified by gene expression profiling into germinal center and activated B-cell subtypes with different prognoses after rituximab-CHOP. The importance of previously recognized prognostic markers, such as Bcl-2 protein expression and BCL2 gene abnormalities, has been questioned in the new therapeutic era. We analyzed Bcl-2 protein expression, and BCL2 and MYC gene abnormalities by interphase fluorescence in situ hybridization in 327 patients with de novo disease treated with rituximab-CHOP. Isolated BCL2 and MYC rearrangements were not predictive of outcome in our patients as a whole, but only in those with the germinal center subtype of lymphoma. The prognostic relevance of isolated MYC rearrangements was weaker than that of BCL2 isolated translocations, but was probably limited by the rarity of the rearrangements. Seven of eight patients with double hit lymphoma had the germinal center subtype with poor outcome. The germinal center subtype patients with isolated BCL2 translocations had significantly worse outcome than the patients without BCL2 rearrangements (P=0.0002), and their outcome was similar to that of patients with the activated B-cell subtype (P=0.30), but not as bad as the outcome of patients with double hit lymphoma (P<0.0001). Bcl-2 protein overexpression was associated with inferior outcome in patients with germinal center subtype lymphoma, but multivariate analysis showed that this was dependent on BCL2 translocations. The gene expression profiling of patients with BCL2 rearrangements was unique, showing activation of pathways that were silent in the negative counterpart. BCL2 translocated germinal center subtype patients have worse prognosis after rituximab-CHOP, irrespective of MYC status, but the presence of combined gene breaks significantly overcomes the prognostic relevance of isolated lesions.

Variation in BCL2 protein expression in follicular lymphomas without t(14;18) chromosomal translocations

AIM

The hallmark of follicular lymphoma is the t(14;18)(q32;q21) chromosomal translocations that lead to deregulation of BCL2 expression in tumour cells. However, not all cases of follicular lymphoma express BCL2, nor is the t(14;18) translocation always present. Follicular lymphomas lacking the BCL2 rearrangement are less well studied with regards to their immunohistochemical and molecular features. This study aims to investigate the BCL2 protein expression pattern in t(14;18) negative follicular lymphomas.

METHODS

BCL2 protein expression pattern was analysed in 26 cases of t(14;18) negative follicular lymphoma [determined by fluorescence in situ hybridisation (FISH)], using antibodies against two-different epitopes, i.e., the widely-used antibody BCL2/124 and an alternative antibody E17.

RESULTS

Two of the t(14;18) negative cases showed evidence of BCL2 amplification and trisomy 18. A total of 13 cases (50%) lacked BCL2 expression. In 10 cases (38%) the expression was heterogeneous and in only three cases (12%) the BCL2 expression was strongly positive. These cases could thus be subdivided into three subgroups: Group I, normal BCL2 genes (i.e., no evidence of translocation or amplification), and BCL2 protein negative; Group II, normal BCL2 genes but BCL2 protein positive; and Group III, presence of other genetic alterations, i.e., BCL2 amplification and trisomy 18, and BCL2 protein positive.

CONCLUSIONS

This study suggests that it may be possible on the basis of staining to predict that the t(14;18) translocation is absent if a case is either negative for BCL2 protein with different antibodies or has heterogeneous BCL2 expression, possibly acquired through a physiological process of differentiation.

Significance of Bcl-2 and Bcl-6 immunostaining in B-Non Hodgkin's lymphoma

The determination of prognosis for B-Non-Hodgkin's lymphoma (NHL) is known to be related to the multiple differences in tumor cell biology. Bcl-2 and Bcl-6 are two markers linked to germinal center B cells. Both markers are thought to have an effect on prognosis of mature B-cell neoplasms. Forty-four patients with chronic B-cell neoplasm were included; Bcl-2 and Bcl-6 expression by immunohistochemistry was examined. Bcl-2 protein was positive in 36.4% (16 of 44) of cases (62.5% of follicular lymphoma, 16.7% of mantle cell lymphoma and 30% of diffuse large B-cell lymphoma); the positive group implying a bad prognostic effect of the marker in NHL. Bcl-6 was positive in 13.6% (6 of 44) of cases (11.1% of mantle cell lymphoma and 40% of diffuse large B-cell lymphoma) and its positivity implies a better disease course. Bcl-2 and Bcl-6 can be used as prognostic marker in NHL.

BCL2 predicts survival in germinal center B-cell-like diffuse large B-cell lymphoma treated with CHOP-like therapy and rituximab

PURPOSE

We have previously shown the prognostic significance of BCL2 expression in the activated B-cell-like diffuse large B-cell lymphoma (ABC-DLBCL) patients treated with cyclophosphamide-Adriamycin-vincristine-prednisone (CHOP) or CHOP-like therapy. However, after the inclusion of rituximab (R) in the CHOP regimen, several conflicting observations about the prognostic value of BCL2 expression have been reported.

EXPERIMENTAL DESIGN

We evaluated the R-CHOP cohort of 221 DLBCL cases with gene expression profiling data. BCL2 protein (n = 169), mRNA (n = 221) expression, and t(14;18) (n = 144) were correlated with clinical outcome. The CHOP cohort (n = 181) was used for comparative analysis.

RESULTS

BCL2 protein expression has significant impact on overall survival (OS) and event-free survival (EFS) in DLBCL (OS, P = 0.009; EFS, P = 0.001) and GCB-DLBCL (OS, P = 0.03; EFS, P = 0.002) but not in ABC-DLBCL in the R-CHOP cohort. The survival differences for EFS in GCB-DLBCL were still observed in multivariate analysis. At the mRNA level, this correlation was observed in EFS in DLBCL (P = 0.006), but only a trend was observed in GCB-DLBCL (P = 0.09). The t(14;18) was detected in 34% of GCB-DLBCL but was not associated with significant differences in survival. Gene enrichment analysis identified significant enrichment of the DLBCL "stromal-1" signatures and hypoxia-inducible factor 1 (HIF1-α) signature in BCL2(-)GCB-DLBCL, whereas T(FH) cell signatures were enriched in BCL2(+)GCB-DLBCL.

CONCLUSION

The prognostic significance of BCL2 has changed after inclusion of rituximab in the treatment protocol and is observed in the GCB-DLBCL rather than the ABC-DLBCL. Although rituximab has benefited patients in both DLBCL subgroups, the BCL2(+)GCB-DLBCL seems to receive less benefit from this treatment and may require other novel therapeutic intervention.

Prognostic biomarkers in malignant lymphomas

There has recently been a rapid expansion in research aimed at identifying biomarkers that could improve the prognosis for patients with various subtypes of malignant lymphoma. Genomic and genetic studies have led to the identification of biological and clinical subgroups of diffuse large B-cell lymphomas with distinct underlying molecular features, divergent activation of oncogenetic pathways, and clinical course. Molecular studies of follicular lymphoma have suggested complex interactions between malignant cells and the surrounding immunological network that could affect disease progression. Moreover, the inflammatory cells of Hodgkin lymphoma have been shown to produce a complex network of cytokines and chemokines that provide a permissive microenvironment for tumor growth. Research into specific biomarkers and signaling pathways of malignant lymphomas might therefore result in the identification of novel targets for future therapeutic strategies. As gene expression profiling techniques are not yet feasible in the clinical laboratory, studies have aimed to translate the findings into more widely applicable techniques that might allow this research to be applied to routine clinical practice. This review focuses on recent advances in translational and clinical research on biomarkers in malignant lymphomas.

The essential role of evasion from cell death in cancer

The link between evasion of apoptosis and the development of cellular hyperplasia and ultimately cancer is implicitly clear if one considers how many cells are produced each day and, hence, how many cells must die to make room for the new ones (reviewed in Raff, 1996). Furthermore, cells are frequently experiencing noxious stimuli that can cause lesions in their DNA and faults in DNA replication can occur during cellular proliferation. Such DNA damage needs to be repaired efficiently or cells with irreparable damage must be killed to prevent subsequent division of aberrant cells that may fuel tumorigenesis (reviewed in Weinberg, 2007). The detection of genetic lesions in human cancers that activate prosurvival genes or disable proapoptotic genes have provided the first evidence that defects in programmed cell death can cause cancer (Tagawa et al., 2005; Tsujimoto et al., 1984; Vaux, Cory, and Adams, 1988) and this concept was proven by studies with genetically modified mice (Egle et al., 2004b; Strasser et al., 1990a). It is therefore now widely accepted that evasion of apoptosis is a requirement for both neoplastic transformation and sustained growth of cancer cells (reviewed in Cory and Adams, 2002; Hanahan and Weinberg, 2000; Weinberg, 2007). Importantly, apoptosis is also a major contributor to anticancer therapy-induced killing of tumor cells (reviewed in Cory and Adams, 2002; Cragg et al., 2009). Consequently, a detailed understanding of apoptotic cell death will help to better comprehend the complexities of tumorigenesis and should assist with the development of improved targeted therapies for cancer based on the direct activation of the apoptotic machinery (reviewed in Lessene, Czabotar, and Colman, 2008).

Translocation t(14;18)/IGH-BCL2 in gastrointestinal follicular lymphoma: correlation with clinicopathologic features in 48 patients

BACKGROUND

Chromosomal translocation t(14;18)(q32;q21) involving the immunoglobulin heavy chain gene (IGH) and the BCL2 gene (t[14;18][q32;q21]/IGH-BCL2) is present in 60% to 90% of nodal follicular lymphomas. To the authors' knowledge, the prevalence and clinical significance of this translocation have not been examined previously in gastrointestinal follicular lymphomas.

METHODS

Clinicopathologic and molecular features were investigated in 48 patients who had gastrointestinal follicular lymphoma. The site of involvement was the duodenum in 54% of patients, the jejunum in 52%, the ileum in 52%, the stomach in 29%, and the colorectum in 15%. The presence of the t(14;18)/IGH-BCL2 translocation was detected by interphase fluorescence in situ hybridization.

RESULTS

Treatment modalities included surgical resection (n = 16), rituximab plus chemotherapy (n = 13), rituximab alone (n = 6), antibiotics (n = 5), and watchful waiting (n = 8). Complete remission (CR) of lymphoma was achieved in 31 patients (65%). The overall survival and event-free survival rates after 5 years were 93% and 68%, respectively. The t(14;18)/IGH-BCL2 was detected in 39 patients (81%). The involvement of multiple sites (69% vs 0%), manifestation of the lymphomatous polyposis type (72% vs 22%), and histologic grade 1 or 2 tumors (92% vs 56%) were more frequent in the t(14;18)-positive group than in the negative group. In addition, the CR rate was lower in the t(14;18)-positive group than in the negative group (56% vs 100%; P = .0179), and a trend was observed toward poorer event-free survival in the positive group (P = .089).

CONCLUSIONS

The t(14;18)/IGH-BCL2 chromosomal translocation occurred frequently in gastrointestinal follicular lymphomas. The current results indicated that this translocation may be a predictor of an adverse clinical course.

BCL2 gene aberration as an IPI-independent marker for poor outcome in non-germinal-centre diffuse large B cell lymphoma

Aim:

Diffuse large B cell lymphoma (DLBCL) is the most common lymphoid malignancy in the western hemisphere, and is characterised by a highly variable outcome that impedes individual risk assessment. Lacking reliable biomarkers, the international prognostic index (IPI) has been the most reliable factor to predict survival and stratify patients for therapy. The aim of this study was to investigate the frequency and potential prognostic role of BCL2 aberrations on the chromosomal level and the protein level in a large DLBCL collective.

Methods:

Fluorescence in situ hybridisation (FISH) with commercially available dual-colour break-apart probes and immunohistochemistry were used to assess BCL2 gene abnormalities and bcl2 protein expression on validated tissue microarrays containing 224 well-characterised cases of primary DLBCL.

Results:

FISH analysis of BCL2 revealed a break in 40/215 cases (19%) and a gain in 66/171 (39%) cases. Only BCL2 gains correlated with bcl2 protein expression (p = 0.001). Presence of any BCL2 gene abnormality, particularly gains, correlated independently of the IPI with a significantly worse prognosis in DLBCL of non-germinal centre (non-GC) phenotype as opposed to DLBCL of non-GC type without this genetic alteration (p = 0.003). DLBCL of germinal centre phenotype did not show this association.

Conclusions:

Cases of DLBCL of the non-GC type with BCL2 gene aberration are accompanied by a significantly worse prognosis as opposed to cases without such gene abnormalities. It may be helpful to asses BCL2 gene abnormalities by FISH in addition to assessing established parameters for individual risk estimation in DLBCL.

Bcl-2 family proteins and cancer

BCL-2 was the first anti-death gene discovered, a milestone with far reaching implications for tumor biology. Multiple members of the human Bcl-2 family of apoptosis-regulating proteins have been identified, including six antiapoptotic, three structurally similar proapoptotic proteins and several structurally diverse proapoptotic interacting proteins that operate as upstream agonists or antagonists. These proteins, in turn, are regulated through myriad post-translational modifications and interactions with other proteins. Bcl-2-family proteins regulate all major types of cell death, including apoptosis, necrosis and autophagy, thus operating as nodal points at the convergence of multiple pathways with broad relevance to oncology. Experimental therapies targeting Bcl-2-family mRNAs or proteins are currently in clinical testing, raising hopes that a new class of anticancer drugs may soon be available.

Evaluation of intra- and interobserver agreement and its clinical significance for scoring bcl-2 immunohistochemical expression in diffuse large B-cell lymphoma

Immunohistochemistry (IHC) has become an essential part of diagnosis and clinical research in lymphomas. There is considerable heterogeneity, however, in IHC findings regarding expression rate and positivity cut-offs, which creates a degree of uncertainty that has prevented its incorporation for prognostic purposes. The purpose of the present study was to assess intra- and interobserver agreement in scoring bcl-2 expression on IHC. The study materials were 81 diffuse large B-cell lymphomas. Slides were processed in the same laboratory, and were analyzed independently and in a blinded manner by four pathologists twice, at least 1 month apart. The positivity rates ranged from 31% to 41% in the first evaluation, and from 30% to 43% in the second evaluation. The two analyses by the same pathologist gave concordant results in 88-93% of cases (kappa = 0.71-0.83). Complete agreement among all observers varied from 72% to 79%. The experience of the observer did not influence intra-observer concordance. Cooperative analysis of discordant slides led to consensus in all cases. The variation observed in scoring bcl-2 expression is acceptable for use in lymphoma diagnosis and classification. The use of IHC stratification, however, for clinical decisions regarding treatment will require standardization and centralized consensus review, and must await the results of ongoing prospective trials.

Bcl-2-family proteins and hematologic malignancies: history and future prospects

BCL-2 was the first antideath gene discovered, a milestone that effectively launched a new era in cell death research. Since its discovery more than 2 decades ago, multiple members of the human Bcl-2 family of apoptosis-regulating proteins have been identified, including 6 antiapoptotic proteins, 3 structurally similar proapoptotic proteins, and several structurally diverse proapoptotic interacting proteins that operate as upstream agonists or antagonists. Bcl-2-family proteins regulate all major types of cell death, including apoptosis, necrosis, and autophagy. As such, they operate as nodal points at the convergence of multiple pathways with broad relevance to biology and medicine. Bcl-2 derives its name from its original discovery in the context of B-cell lymphomas, where chromosomal translocations commonly activate the BCL-2 protooncogene, endowing B cells with a selective survival advantage that promotes their neoplastic expansion. The concept that defective programmed cell death contributes to malignancy was established by studies of Bcl-2, representing a major step forward in current understanding of tumorigenesis. Experimental therapies targeting Bcl-2 family mRNAs or proteins are currently in clinical testing, raising hopes that a new class of anticancer drugs may be near.

Presence of simian virus 40 in diffuse large B-cell lymphomas in Tunisia correlates with germinal center B-cell immunophenotype, t(14;18) translocation, and P53 accumulation

Previously we have reported the presence of simian virus 40 DNA in 56% of diffuse large B-cell lymphomas in Tunisia. Here, we investigated the relationship between the status of simian virus 40 and t(14;18) translocation, germinal center status, and P53 and BCL2 expression to assess the clinical and biological relevance of simian virus 40 presence in diffuse large B-cell lymphomas. Therefore, we evaluated by immunohistochemistry the expression patterns of CD10, BCL6, MUM1, BCL2, and P53 in 86 diffuse large B-cell lymphomas (48 simian virus 40-positive and 38 simian virus 40-negative cases). The t(14;18) translocation was investigated by polymerase chain reaction. Immunostaining patterns for CD10, BCL6, and MUM1 were used to subclassify diffuse large B-cell lymphoma cases as germinal center or non-germinal center phenotypes. Germinal center phenotype, t(14;18), P53, and BCL2 expression were found in 71, 30, 55, and 65% of cases, respectively. Interestingly, germinal center phenotype, t(14;18), and P53 accumulation were found to be more frequent in simian virus 40-positive cases than in simian virus 40-negative ones (81, 44, 69 vs 58, 13, 37%; P=0.018, 0.002, and 0.003, respectively). However, there were no correlations between the presence of simian virus 40 and the expression of CD10, BCL6, MUM1 and BCL2, patient's age and gender, clinical stage, or the International Prognosis Index. Multivariate logistic regression analyses revealed that the germinal center phenotype, P53 accumulation, and t(14;18) were independent factors for simian virus 40 association (P=0.029, 0.006, and 0.014, respectively). There were no significant differences in overall survival regarding P53, BCL2, or t(14;18) status. However, patients with germinal center phenotype or low International Prognosis Index scores displayed a significantly better survival than those with non-germinal center phenotype or high International Prognosis Index scores (P=0.003 and 0.0001, respectively). These two prognosis factors remain independent in multivariate analyses (P=0.001 and <0.0001, respectively). Interestingly, among patients with germinal center phenotype, simian virus 40-positive subgroup displayed a significantly shorter survival than simian virus 40-negative subgroup (P=0.034). In summary, these findings support a role of simian virus 40 in the pathogenesis of diffuse large B-cell lymphomas. On other hand, they suggest that a significant proportion of diffuse large B-cell lymphoma cases with germinal center phenotype may result from early transformation by simian virus 40, mainly those harboring the t(14;18). Modern Pathology (2008) 21, 282-296; doi:10.1038/modpathol.3800993; published online 28 December 2007.

Immunophenotype as prognostic factor for diffuse large B-cell lymphoma in patients undergoing clinical risk-adapted therapy

BACKGROUND

For patients with diffuse large B-cell lymphoma (DLBCL), the International Prognostic Index (IPI) predicts the likelihood for cure with chemotherapy. Biological parameters, including expression of Bcl-6, Bcl-2, CD10, major histocompatibility complex class II, and categorization as germinal center (GC) type have been described as IPI-independent prognostic factors.

PATIENTS AND METHODS

Biological parameters were evaluated retrospectively by immunohistochemistry in 60 consecutive DLBCL patients of the prerituximab era. Forty-one of 60 patients underwent a risk-adapted treatment strategy including autologous stem-cell transplantation for high-risk patients (age-adjusted IPI = 2-3; slow response to chemotherapy).

RESULTS

Bcl-6 expression was associated with superior overall survival (OS) independently of the IPI. Inferior progression-free survival (PFS) was independently correlated with high expression of Bcl-2 and low positivity for HLA-DR and CD10. Distinction into GC and non-GC DLBCL on the basis of Bcl-6, CD10, and IRF-4 expression had no independent prognostic value. Within the risk-adapted treatment strategy, only HLA-DR retained a prognostic impact on OS (P = 0.0058) and PFS (P = 0.0002).

CONCLUSIONS

In 60 patients with DLBCL treated with risk-adapted therapy, immunohistochemical subcategorization of DLBCL into GC and non-GC type has little clinical value. The IPI-associated risk appears to be mitigated by intensified upfront therapy. Low HLA-DR expression is associated with poor outcome after intensified upfront therapy. Therefore, additional treatment modalities appear to be required.

Detection of the bcl-2 t(14;18) translocation and proto-oncogene expression in primary intraocular lymphoma

PURPOSE

Primary intraocular lymphoma (PIOL) is a diffuse large B cell lymphoma that initially infiltrates the retina, vitreous, or optic nerve head, with or without central nervous system involvement. This study examined the expression of the bcl-2 t(14;18) translocation, the bcl-10 gene, and high expression of bcl-6 mRNA in PIOL cells.

METHODS

Microdissection and PCR analysis were used to examine vitreous specimens in patients with PIOL for the presence of bcl-2 t(14;18) translocations, the bcl-10 gene, and expression of bcl-6 mRNA. A medical record review was also conducted to determine whether the bcl-2 t(14;18) translocation correlated with prognosis.

RESULTS

Forty of 72 (55%) PIOL patients expressed the bcl-2 t(14;18) translocation at the major breakpoint region. Fifteen of 68 (22%) patients expressed the translocation at the minor cluster region. The bcl-10 gene was detected in 6 of 26 (23%) patients, whereas 4 of 4 (100%) PIOL patients expressed higher levels of bcl-6 mRNA compared with inflammatory lymphocytes. An analysis of clinical outcome in 23 PIOL patients revealed no significant association between bcl-2 t(14;18) translocations and survival or relapse. However, patients with the translocation were significantly younger.

CONCLUSIONS

PIOL has unique molecular patterns of bcl-2, bcl-10, and bcl-6 when compared with other systemic lymphomas. This study lays the foundation for future studies aimed at exploring the genotypic classification of PIOL based on the quantitative molecular framework of gene expression profiling, with the goal of providing useful adjuncts to the pathologic diagnosis of this complex disease.

BCL2 expression is a prognostic marker for the activated B-cell-like type of diffuse large B-cell lymphoma

BACKGROUND

The role of BCL2 as a predictor of survival in diffuse large B-cell lymphoma (DLBCL) is controversial. DLBCL is heterogeneous, and the expression of BCL2 is variable within the two major subgroups of DLBCL, germinal center B-cell-like (GCB) and activated B-cell-like (ABC) DLBCL, as well as primary mediastinal DLBCL.

PATIENTS AND METHODS

In this study, we investigated the correlation of BCL2 expression with survival in the two major subgroups of DLBCL, as well as the mechanisms of BCL2 expression.

RESULTS

There was no significant correlation between BCL2 protein expression and overall survival within the GCB subgroup, but BCL2 expression had a significant adverse effect on overall survival within the ABC subgroup (P = .008). This correlation was also observed at the mRNA level (P < .04). The difference remained significant when the analyses were performed at different cutoff values. The t(14;18) was frequently observed in the GCB subgroup and was highly associated with BCL2 expression. Patients with ABC DLBCL did not exhibit t(14;18) but had a markedly higher frequency of chromosome 18q21 amplification, on which BCL2 resides. Thus, alternative mechanisms such as 18q21 amplification or activation of the nuclear factor-kappa B pathway, as reported previously, seem to be mainly responsible for the upregulation of BCL2 expression in the ABC subgroup.

CONCLUSION

Treating all DLBCL as a single entity ignores the mechanistic differences in BCL2 upregulation and obscures the prognostic significance of BCL2 expression. Hence, the significance of BCL2 and other biomarkers should be assessed in the context of DLBCL subgroups in future studies.

Biomarkers of potential prognostic significance in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a biologically heterogeneous disease for which the current approach to treatment is only successful for 50% of patients. The prognostic value of various clinical and biological factors in predicting treatment outcome is discussed in this paper. A review of the English literature was performed including original articles and relevant reviews from MEDLINE that addressed the topics of DLBCL biology and potential prognostic factors. The International Prognostic Index is, to date, the most successful clinical model for predicting outcome. In addition, a rapidly expanding list of molecules has been identified by conventional and newer diagnostic methods that may be of significant prognostic value. Gene expression profiling has led to the discovery of new biological subtypes of DLBCL based on patterns of gene expression, and a host of new genes that may play important roles in this disease. Various derangements in apoptosis, cell-cycle regulation, differentiation, and signal transduction have been noted, while the host environment and immune response also appear to modify clinical outcome. Although to our knowledge, the fundamental abnormalities underlying DLBCL remain elusive, progress is being continuously made to further the understanding of the biological heterogeneity of this disease and the use of various clinical and biological variables to predict treatment outcome. The goal is to be able to identify subgroups of patients at high risk of treatment failure and develop more effective treatment based on specific biological defects that may represent new rational therapeutic targets.

Large Cleaved and Immunoblastic Lymphoma May Represent Two Distinct Clinicopathologic Entities Within the Group of Diffuse Large B-Cell Lymphomas

Purpose

The reliability of immunohistochemistry for subdividing diffuse large B-cell lymphomas (DLBCL) into germinal center B-cell-like (GCB) and non-GCB prognostic subgroups is debated. In this study we evaluated the prognostic significance of such subgrouping on a series of 153 DLBCL patients. Furthermore, we investigated whether both subgroups could comprise clinicopathologic entities recognized by their morphology and characterized by a distinct phenotype, specific genetic abnormalities, and clinical characteristics.

Patients and Methods

All samples from patients were reviewed and morphologically subdivided into large cleaved, immunoblastic, and not otherwise specified DLBCL. GCB and non-GCB immunohistochemical profiles were established. The presence of chromosomal translocations involving BCL2, BCL6, and MYC and/or rearrangements of these genes was investigated.

Results

Subdividing DLBCL with either a GCB or non-GCB immunophenotypic profile was not of prognostic significance. Nevertheless, CD10 expression was a predictor of favorable outcome, whereas high bcl-2 expression and BCL6 rearrangement were adverse predictors of disease-free survival. Interestingly, large cleaved DLBCL was clearly associated with a GCB immunophenotypic profile, CD10 expression, BCL2 rearrangement, age younger than 60 years, and low to low/intermediate International Prognostic Index risk, but was not of prognostic significance. In contrast, immunoblastic morphology was associated with a non-GCB profile and was a significant predictor of unfavorable DFS.

Conclusion

Subdividing DLBCL into subgroups based on their immunohistochemical profile was not of prognostic significance. Nevertheless, it allowed the additional characterization of two lymphoma subgroups previously recognized in the Working Formulation. Both correspond to two distinct clinicopathologic entities within the DLBCL.

Expression of PKC-beta or cyclin D2 predicts for inferior survival in diffuse large B-cell lymphoma

We sought to determine whether identification of poor-risk subgroups of diffuse large B-cell lymphoma (DLBCL) using immunohistochemical stains would have practical utility with regard to prognosis and therapeutic decisions. Tissue microarray blocks were created using replicate samples of formalin-fixed, paraffin-embedded tissue from 200 cases of de novo DLBCL. The sections were stained with antibodies to proteins that are expressed by activated or proliferating B cells including MUM1, FOXP1, bcl-2, survivin, protein kinase C-beta (PKC-beta), cyclin D2, cyclin D3, and Ki-67. In univariate analysis, tumor expression of cyclin D2 (P = 0.025) or PKC-beta (P = 0.015) was associated with a worse overall survival, whereas none of the other markers was predictive of overall survival. Patients with DLBCL that expressed either cyclin D2 or PKC-beta had a 5-year overall survival of only 30% as compared to 52% for those who were negative for both markers (P = 0.0019). In multivariate analysis, the expression of cyclin D2 or PKC-beta was an independent predictor of poor overall survival (P = 0.035). Cyclin D2 and PKC-beta expression will be useful in designing a 'biological prognostic index' for patients with DLBCL.

The t(14;18) in Diffuse Large B-Cell Lymphoma

The clinical and biologic relevance of the t(14;18) and features of germinal center (GC) differentiation in diffuse large B-cell lymphoma (DLBCL) remain controversial. The authors examined the association of t(14;18) with GC-associated markers and clinical features in 44 de novo DLBCLs (22 nodal and 22 primary extranodal). CD10, bcl-2, and bcl-6 were expressed in 50%, 62%, and 54% of cases respectively. There were no significant differences in expression of these markers between nodal and extranodal cases. Coexpression of CD10 and bcl-6 was seen in 12 of 41 cases, and was more frequent in nodal than extranodal DLBCL (9 of 21 vs. 3 of 20; P = 0.05). A CD10+/bcl-6+ phenotype was not significantly associated with bcl-2 expression, stage, complete remission rate, or survival. The t(14;18) was found in 7 of 44 (16%) cases (6 nodal, 1 extranodal; P = 0.09). It was associated with a CD10+/bcl-6+ phenotype (5 of 7 vs. 7 of 27; P = 0.015) and a trend toward more frequent bcl-6 expression (6 of 7 vs. 15 of 34; P = 0.09), but no association with bcl-2 expression, CD10, clinical stage, complete remission, or survival. Among nodal or high-stage (III-IV) DLBCL, cases with the t(14;18) showed a trend toward decreased survival (P = 0.12).

Incidence of Diffuse Large B-Cell Lymphoma of Germinal Center B-Cell Origin in Whole Diffuse Large B-Cell Lymphoma: Tissue Fluorescence In Situ Hybridization Using t(14;18) Compared with Immunohistochemistry

Diffuse large B-cell lymphoma (DLBCL) can be divided into prognostically important categories such as germinal center B (GCB)-like and non-GCB-like groups. The t(14;18)(q32;q21) translocation defines a unique subset of DLBCL cases with a GCB gene expression profile. Two-color fluorescence in situ hybridization (FISH) analysis was applied to detect t(14;18) (q32;q21) in the nuclei of paraffin-embedded tissue sections from 61 patients with de novo DLBCL. Nine (15%) of 61 cases had a positive pattern. Fifty-seven cases were subclassified in an immunohistochemical study with anti-CD10, anti-bcl-6, and anti-MUM1 antibodies. In this classification, 21 cases (37%) were placed in the GCB group, and 36 (63%) were placed in the non-GCB group. There was a discrepancy between t(14;18) occurrence and bcl-2 protein expression. Bcl-2 protein expression was positive in 40 (67%) of 60 cases. The expression of bcl-2 protein in the GCB and non-GCB groups was not significantly different: 15 (71%) of 21 cases in the GCB group and 24 (67%) of 36 cases in the non-GCB group tested positive. We found no difference between the FISH-positive and FISH-negative groups in overall survival time (P = .6019, log-rank test). The overall survival rates of GCB and non-GCB groups did not differ significantly by immunohistochemical classification (P = .5399, log-rank test). Overall survival was significantly longer in the group with a low International Prognostic Index (IPI) score than in the group with a high IPI score (P = .0002, log-rank test). Our results suggest that immunohistochemical study and cytogenetic study with t(14;18) FISH cannot predict the clinical outcomes of DLBCL patients. A study with a larger number of patients may show a difference in clinical outcomes between FISH-positive and FISH-negative groups and between GCB and non-GCB groups.

Clinicopathologic Significance and Prognostic Value of Chromosomal Imbalances in Diffuse Large B-Cell Lymphomas

Purpose

To determine the clinicopathologic significance and prognostic value of chromosomal imbalances in diffuse large B-cell lymphomas (DLBCL).

Patients and Methods

We have examined 64 tumors at diagnosis using comparative genomic hybridization and real-time quantitative polymerase chain reaction (PCR), single-stranded conformational polymorphism, and DNA sequencing for the analysis of several potential target genes.

Results

The most recurrent alterations were gains of 18q (20%), Xq (15%), 2p, 7q, and 12p (14%), and losses of 6q and 17p (14%). Frequent high-level DNA amplifications were detected at 2p13-p16 and 18q21 loci. Real-time quantitative PCR detected REL and BCL11A gene amplifications in the nine patients with gains at 2p13-p16 and only in one additional patient with normal chromosome 2. Similarly, the BCL-2 gene was amplified in the 12 tumors with gains of 18q21 but in none of 39 patients with normal 18q profile. p53 gene inactivation was detected in nine of 58 (16%) tumors and was commonly associated with 17p losses. Tumors with 18q gains were significantly associated with a high number of chromosomal imbalances, primary nodal presentation, high serum lactate dehydrogenase levels, high International Prognostic Index, shorter cause-specific survival, and a high risk of relapse. Losses of 17p and p53 gene alterations were associated with an absence of complete response achievement.

Conclusion

These results suggest that DLBCLs have a characteristic pattern of genomic alterations; 18q gains or amplifications and 17p losses are associated with particular clinicopathological features and aggressive clinical behavior. Additional studies are needed to confirm these observations in larger series of patients.

Molecular heterogeneity of diffuse large B-cell lymphoma: implications for disease management and prognosis

Diffuse large B-cell lymphoma (DLBCL) accounts for approximately 40% of all B-cell non-Hodgkin lymphomas of the Western world. According to the "WHO classification of tumours of the haematopoietic and lymphoid tissues", the term DLBCL is likely to include more than one disease entity, as suggested by the marked variability of the clinical presentation and response to treatment of this disease. Such heterogeneity may reflect the occurrence of distinct molecular subtypes of DLBCL as well as differences in the host's immune function. In immunocompetent hosts, approximately 50% DLBCL carry one of two primary molecular lesions defining two distinct genotypic subgroups, characterized by activation of either the BCL-6 or the BCL-2 proto-oncogene. Conversely, the remaining DLBCL of immunocompetent hosts display one of several molecular lesions, each associated with a small subset of cases and including activation of the proto-oncogenes REL, MUC-1, BCL-8 and c-MYC. The molecular pathogenesis of immunodeficiency-associated DLBCL differs substantially from that of DLBCL in immunocompetent hosts. In fact, EBV infection is present in a large fraction of immunodeficiency-associated DLBCL, whereas it is consistently negative in DLBCL of immunocompetent hosts, probably reflecting the critical role of disruption of the immune system in this disease. Finally, the application of DNA microarray technology to DLBCL has led to the distinction of two disease variants: a germinal center like DLBCL and an activated peripheral B-cell like DLBCL. Overall the molecular features of DLBCL may identify prognostic categories of the disease and may represent a powerful tool for therapeutic stratification.

Molecular pathology in the diagnosis and treatment of non-Hodgkin's lymphomas

The non-Hodgkin's lymphomas encompass a wide spectrum of hematologic neoplasms that exhibit different clinical and biological features. Lymphomas classically have been initially assessed based on their cytologic and histologic features. Morphology alone is often inadequate as similar appearing neoplasms may be immunophenotypically and molecularly heterogeneous. Molecular diagnostic methods can provide an additional level of testing that not only helps refine diagnoses but can provide prognostic information. New methods are being refined that may provide information to establish precise diagnostic profiles, provide targets for therapy and provide more sensitive methods for monitoring the success of treatment. Molecular methods will be increasingly utilized and eventually required as the accepted method of diagnosis and for monitoring the disease. Understanding of the molecular abnormality and the pathogenesis of the neoplasm hopefully will lead to therapeutic intervention aimed at the specific molecular defect or its product. The molecular pathology of the non-Hodgkin's lymphomas is discussed.

Evaluation of vitrectomy specimens and chorioretinal biopsies in the diagnosis of primary intraocular lymphoma in patients with Masquerade syndrome

PURPOSE

To correlate the histopathological diagnoses established by diagnostic vitrectomy and chorioretinal biopsy in patients with clinically suspected primary intraocular lymphoma (PIOL) or chronic idiopathic uveitis, and the clinical follow-up data.

METHODS

Eighty-four consecutive pars plana vitrectomy (PPV) specimens, three chorioretinal biopsies and two enucleated eyes taken from 80 patients were evaluated. All PPV specimens were unfixed; these were centrifuged, the "cytospins" being stained conventionally (May-Grünwald-Giemsa) and using immunocytology (CD79a, CD3, CD68, immunoglobulin (Ig) light chains). An extended immunohistochemical panel, as well as polymerase chain reaction (PCR) for rearrangements of the Ig heavy chain gene (IgH-PCR), were used to investigate the chorioretinal biopsies and the enucleated eyes. Diagnoses, made on the basis of morphology and immunophenotype, included "reactive cellular infiltrate", "malignant lymphoma", "suspicious of neoplastic disease", and "insufficient for diagnosis". The corresponding clinical data were collected and compared with the diagnosis.

RESULTS

The 80 patients consisted of 46 women and 34 men. The patients' age range varied from 21 to 100 years (mean age 62 years). Sixty-two (74%) of the 84 vitrectomy specimens were diagnosed as "reactive cellular infiltrate", 12 (14%) as definite "malignant lymphoma", 5 (6%) as "suspicious of neoplastic disease" and 5 (6%) specimens were considered "insufficient for diagnosis". An additional chorioretinal biopsy enabled an unequivocal diagnosis of PIOL to be reached in 3 patients. All PIOL were diffuse large cell B-cell lymphoma (DLBCL), with the immunophenotype CD79+, CD20+, BCL-2+, BCL-6+, MUM1+ and monotypical expression for IgM+. A monoclonal IgH-PCR amplification product was obtained in four vitrectomy specimens, two chorioretinal biopsies and one of the enucleated eyes. Comparison of the diagnoses with long-term follow-up clinical data resulted in concordance in 77 (96%) cases and discrepancies ("false-negative" diagnoses) in 3 patients (4%). The patients diagnosed with lymphoma were treated with either radiotherapy, chemotherapy or both. At final follow-up (mean 35 months), 5 patients (6%) had developed cerebral lymphomatous manifestation, and 7 (9%) had succumbed to their disease.

CONCLUSION

The diagnosis of PIOL is often extremely difficult, requiring sufficient rapidly transported good-quality material, and experienced interpretation. Although cytological examination of vitreal aspirates remains the gold standard in diagnosis, examination of chorioretinal biopsies increase the reliability of diagnosing or excluding a PIOL that involves the retina or choroid. Most PIOL are DLBCL with an immunophenotype suggesting a cellular origin from germinal centre cells.

Diffuse large B-cell lymphoma of bone: an analysis of differentiation-associated antigens with clinical correlation

Twenty-nine patients with diffuse large B-cell lymphomas presenting with bone involvement, including 18 localized primary bone lymphomas (group 1), 2 multifocal primary bone lymphomas (group 2), and 9 patients with extraskeletal disease at diagnosis (group 3), were studied. The tumors were subclassified according to the criteria of the WHO classification and evaluated by immunohistochemistry for expression of antigens associated with germinal center (GC) and non-GC stages of B-cell differentiation (bcl-6, CD10, MUM-1, VS38c, CD138, bcl-2, and CD44). The presence of a BCL-2/IgH gene rearrangement was investigated by polymerase chain reaction. All cases were characterized by similar clinicopathologic and morphologic features and had similarly good overall outcome. The patients (23 males, 6 females, median age 44 years) had tumors in long bones (14), axial skeleton (8), limb girdles (3), and multiple sites (4). Most tumors (24) were centroblastic, with multilobated cells in 12 cases. Almost half of the tumors (14 of 29, 48%) were bcl-6+CD10+ (GC-like), 9 of 29 cases (31%) were bcl-6+CD10- (indeterminate phenotype), and 6 of 29 cases (21%) were CD10-bcl-6- (post-GC like). The indeterminate phenotype was seen only in primary bone lymphoma. MUM-1 was frequently expressed in GC-like and non-GC-like categories. We found no evidence of plasmacytic differentiation by CD138, and VS38c immunoreactivity was distinctly rare (2 of 29 cases). CD44 was detected in 6 tumors, all CD10-. Bcl-2 was expressed by 70% of the tumors, but only 1 of 23 cases tested had a Bcl-2/JH rearrangement by polymerase chain reaction. A survival analysis showed that GC-like tumors had a longer overall survival duration compared with non-GC-like tumors (P = 0.0046). In conclusion, a GC-like immunophenotype characterizes roughly half of large B-cell lymphomas of bone and is associated with an improved survival.

Clinical impact of the differentiation profile assessed by immunophenotyping in patients with diffuse large B-cell lymphoma

To analyze the relationship between immunophenotyping profile and main clinicopathological features and outcome in diffuse large B-cell lymphoma (DLBCL), we studied 128 patients (59 men, 69 women; median age 65 years) consecutively diagnosed with de novo DLBCL in a single institution. Cells from each patient were immunostained with CD20, CD79a, CD5, CD10, bcl-6, MUM1, CD138, bcl-2, p53, p27, and Ki-67 antibodies. Four immunophenotyping profiles were distinguished according to the pattern of differentiation: germinal center-CD10(+) (GC-CD10(+); CD10(+)/Bcl-6(+)/MUM1(-)/CD138(-)), germinal center-CD10(-) (GC-CD10(-); CD10(-)/Bcl-6(+)/ MUM1(-)/CD138(-)), post-germinal center (pGC; CD10(-)/bcl-6(+/-)/ MUM1(+)/CD138(-)), and plasmablastic (CD10(-)/bcl-6(-)/MUM1(+)/CD138(+)). Rearrangement of bcl-2 was studied by polymerase chain reaction (PCR) in 57 patients. Single-antigen expression was as follows: CD5, 2%; CD10, 21%; bcl-6, 72%; MUM1, 54%; CD138, 2%; bcl-2, 59%; p53, 28%; p27, 40%. Distribution according to differentiation profiles was as follows: GC-CD10(+), 24 patients, GC-CD10-, 30 patients; pGC, 60 patients; plasmablastic, 2 patients; other patterns, 12 patients. The pGC profile was associated with primary nodal presentation and immunoblastic morphology, whereas GC-CD10(+) tumors showed disseminated disease, centroblastic morphology, bcl-2 rearrangement, and lower Ki-67 proliferative index. GC-CD10(-) patients more often presented with primary extranodal origin, early stage, normal lactic acid dehydrogenase (LDH) levels, and low or low/intermediate International Prognostic Index (IPI) scores than the others. However, no significant difference was found in terms of response or overall survival (OS) according to these profiles. Expression of bcl-2 was associated with advanced stage, high or high-intermediate IPI, and poor OS. Expression of bcl-2 maintained predictive value in multivariate analysis, with stage and LDH. In conclusion, differentiation profile was associated with particular clinicopathological features but was not essential to predicting outcome in DLBCL patients.

BCL-2 expression in Hodgkin and Reed-Sternberg cells of classical Hodgkin disease predicts a poorer prognosis in patients treated with ABVD or equivalent regimens

To determine the clinical significance of BCL-2 expression in Hodgkin-Reed-Sternberg (HRS) cells of classical Hodgkin disease (cHD), we correlated its expression with presenting clinical and laboratory features and failure-free survival (FFS). Eligible patients were untreated and negative for HIV-1; they had biopsy-proven cHD. BCL-2 expression was determined immunohistochemically in available pretreatment tissue biopsy specimens without knowledge of clinical outcome. Tumors were considered positive if any HRS cells expressed BCL-2. We identified 707 patients with cHD, whose median age was 30 years; 54% were men. HRS cells expressed BCL-2 in 359 (65%) of 551 nodular sclerosis, 67 (47%) of 143 mixed cellularity, and all 5 lymphocyte depletion. For all patients, the 5-year FFS was 74% versus 84% for tumors with versus without BCL-2 expression (P =.0016, by log-rank test). For the 412 patients treated with adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD) or equivalent regimens, the 5-year FFS for tumors with versus without BCL-2 expression was 74% versus 88% (P =.001, by log-rank test); for the 233 patients with Ann Arbor stage I or II, FFS was 84% versus 92% (P =.04, by log-rank test); and for the 179 patients with Ann Arbor stage III or IV, FFS was 62% versus 81% (P =.006, by log-rank test). Multivariate analysis confirmed that BCL-2 expression is independently associated with inferior FFS along with age 45 or older, Ann Arbor stage IV, low serum albumin and high serum lactate dehydrogenase levels. We conclude that BCL-2 is frequently expressed by HRS cells in cHD and is associated with inferior FFS in patients treated with ABVD or equivalent regimens.

Analysis of immunoglobulin VH genes in CD10-positive diffuse large B-cell lymphoma

CD10, a proteolytic enzyme seen in germinal center cells and in the majority of follicular lymphomas, is occasionally expressed in diffuse large B-cell lymphomas (DLBCL). To clarify the origin and cellular characteristics of CD10-positive DLBCL, we analyzed 36 de novo cases of DLBCL for somatic mutations of the immunoglobulin heavy chain variable region (VH) genes and for their immunophenotypes. Expression greater than that of grade 2 Bcl-6 was observed in 11 of the 30 CD10-negative cases (37%) and in all six CD10-positive cases (100%; P < 0.05) without expression of CD5, CD23, cyclin D1, CD30 or CD138. The average mutation frequencies of the six CD10-positive and 30 CD10-negative DLBCL were 12.9 and 9.8%, respectively. The range of SM frequencies in CD10-positive DLBCL (9.52-18.06) was distinctly narrower than that observed for CD10-negative DLBCL (0.69-26.89). These findings seem to indicate that CD10-positive DLBCL, originating from germinal center B cells, is a genetically and immunophenotypically more homogeneous group than CD10-negative DLBCL. Furthermore, three extranodal lymphomas, in five of the six CD10-positive DLBCL, showed ongoing mutation, indicating that antigen-driven, high-affinity somatic mutation may play an important role in clonal expansion in CD10-positive DLBCL. All four extranodal cases of the six CD10-positive DLBCL showed ongoing mutation and/or bcl-2/JH rearrangement. This result suggests that the cell origin of extranodal CD10-positive DLBCL may be the same as that of follicular lymphomas.

Primary cutaneous diffuse large B-cell lymphoma: a clinicopathologic study of 15 cases

Primary cutaneous diffuse large B-cell lymphoma (DLBCL) is an uncommon lymphoma. Some authors have suggested that large B-cell lymphoma can be segregated based on anatomic site, with tumors of the lower extremity being unique. We report 15 cases of primary cutaneous DLBCL. Each case was analyzed immunohistochemically using antibodies specific for CD3, CD5, CD10, CD20, bcl-2, bcl-6, and p53. Polymerase chain reaction analysis for t(14;18)(q32;q21) also was performed. There were 13 men and 2 women (median age, 64 years). Thirteen tumors were composed predominantly of centroblasts, and 2 were immunoblastic. There was a median follow-up of 72 months. Of the 4 patients with primary cutaneous DLBCL of the lower extremity (thigh, knee, leg), 2 (50%) experienced a recurrence and 1 patient died of disease. In the non-lower extremity cases, 18% (2/11) recurred and no patients died of disease. We conclude that primary cutaneous DLBCL usually occurs in elderly patients with a male predominance. Recurrences are common, but death of disease is rare.

The t(14;18) defines a unique subset of diffuse large B-cell lymphoma with a germinal center B-cell gene expression profile

Recently we have identified subgroups of de novo primary diffuse large B-cell lymphoma (DLBCL) based on complementary DNA microarray-generated gene expression profiles. To correlate the gene expression profiles with cytogenetic abnormalities in these DLBCLs, we examined the occurrence of the t(14;18)(q32;q21) in the 2 distinctive subgroups of DLBCL: one with the germinal center B-cell gene expression signature and the other with the activated B cell-like gene expression signature. The t(14;18) was detected in 7 of 35 cases (20%). All 7 t(14;18)-positive cases had a germinal center B-cell gene expression profile, representing 35% of the cases in this subgroup, and 6 of these 7 cases had very similar gene expression profiles. The expression of bcl-2 and bcl-6 proteins was not significantly different between the t(14;18)-positive and -negative cases, whereas CD10 was detected only in the group with the germinal center B-cell expression profile, and CD10 was most frequently expressed in the t(14;18)-positive cases. This study supports the validity of subdividing DLBCL into 2 major subgroups by gene expression profiling, with the t(14;18) being an important event in the pathogenesis of a subset of DLBCL arising from germinal center B cells. CD10 protein expression is useful in identifying cases of DLBCL with a germinal center B-cell gene expression profile and is often expressed in cases with the t(14;18).

Spectral karyotyping identifies new rearrangements, translocations, and clinical associations in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL), a histologically well-defined subset of non-Hodgkin lymphoma, is clinically and genetically heterogenous. By G-banding, most cases showed complex hyperdiploid karyotypes and diverse cytogenetic abnormalities that included recurring and nonrecurring translocations, deletions, duplications, and marker chromosomes. While G-banding provided valuable leads to identification of specific rearrangements that enabled gene discovery and clinical correlations, many aberrations remained uncharacterized because of their complexity. The molecular cytogenetic technique spectral karyotyping (SKY), on the other hand, enables complete characterization of all aberrations in a tumor cell karyotype and, hence, precise quantitation of chromosome instability. We report here, for the first time, SKY analysis of a panel of 46 DLBCL cases previously analyzed by G-banding, ascertained at the Memorial Sloan-Kettering Cancer Center. This analysis provided a cytogenetic profile of DLBCL that was characterized by a higher level of instability, qualitatively as well as quantitatively, compared with G-banding. Thus, 551 breakpoints were detected by SKY, in contrast to the 295 by G-banding. Several new recurring breakpoints, translocations, and regions of gain and loss were identified, which included 13 breakpoints not previously identified by G-banding, 10 breakpoints that were underrepresented by G-banding, and 4 previously unrecognized translocations: der(14)t(3;14)(q21;q32), t(1;13)(p32;q14), t(1;7)(q21;q22), and der(6)t(6;8)(q11;q11). We identified new clinical associations involving recurring breakpoints detected by SKY. These studies emphasize the value of SKY analysis for redefinition of chromosomal instability in DLBCL to enhance gene discovery as well as clinical correlation analysis.

Point mutations of the BCL-6 gene: clinical and prognostic correlation in B-diffuse large cell lymphoma

Although point mutations of the 5' noncoding regions of the BCL-6 proto-oncogene are frequently detected in B-diffuse large cell lymphoma (B-DLCL), a thorough analysis of the clinical correlation of these mutations has not been performed to date. In this study, BCL-6 mutations were examined by DNA direct sequencing in 103 patients with B-DLCL. BCL-6 mutations were found in 53/103 patients, including 38/76 treated with standard chemotherapy and 15/27 treated with autologous stem cell transplantation (ASCT) up front. The presence of BCL-6 mutations was correlated with clinical features at diagnosis and outcome. Mutated patients had a significantly higher LDH level (66% vs 38%, P < 0.05), and bulky disease (51% vs 32%, P = 0.05). In the whole series of patients BCL-6 mutations did not affect CR and OS. Patients with BCL-6 mutations tended to have a prolonged 5-years DFS and FFS compared to those without mutations (DFS 82% vs 63%, FFS 63% vs 49%). Among B-DLCL treated with standard chemotherapy, mutated patients showed a significantly improved 5-year DFS (85% vs 61%, P < 0.05) and, notably, the only four relapses observed among mutated patients occurred in less than 8 months. The multivariate regression analysis (P < 0.01) with DFS as endpoint confirmed the independent prognostic value of BCL-6 mutations. There was a trend for 5-year failure-free survival to be better for patients with BCL-6 mutations (63% vs 43%, P = 0.09). In the 27 patients treated with ASCT, BCL-6 mutations did not correlate with outcome. These results suggest that BCL-6 mutations may predict a higher chance of being free of disease in B-DLCL treated with standard chemotherapy. Larger series of patients need to be analyzed to evaluate the clinical relevance of BCL-6 mutations properly.

Proteins encoded by genes involved in chromosomal alterations in lymphoma and leukemia: clinical value of their detection by immunocytochemistry

Acquired chromosomal anomalies (most commonly translocations) in lymphoma and leukemia usually result in either activation of a quiescent gene (by means of immunoglobulin or T-cell-receptor promotors) and expression of an intact protein product, or creation of a fusion gene encoding a chimeric protein. This review summarizes current immunocytochemical studies of these 2 categories of oncogenic protein, with emphasis on the clinical relevance of their detection in diagnostic samples. Among the quiescent genes activated by rearrangement, expression of cyclin D1 (due to rearrangement of the CCND1 [BCL-1] gene) is a near-specific marker of t(11;14) in mantle cell lymphoma; BCL-2 expression distinguishes follicular lymphoma cells from their nonneoplastic counterparts in reactive germinal centers and appears to be an independent prognostic marker in diffuse large cell lymphoma; and TAL-1 (SCL) expression identifies T-cell acute lymphoblastic neoplasms in which this gene is activated. The protein products of other genes activated by chromosomal rearrangement have a role as markers of either lineage (eg, PAX-5 [B-cell-specific activator protein] for B cells, including B-lymphoblastic neoplasms), or maturation stage (eg, BCL-6 for germinal-center and activated B cells and MUM-1/IRF4 for plasma cells). Currently, no hybrid protein encoded by fusion genes is reliably detectable by antibodies recognizing unique junctional epitopes (ie, epitopes absent from the wild-type constituent proteins). Nevertheless, staining for promyelocytic leukemia (PML) protein will detect acute PML with t(15;17) because the microspeckled nuclear labeling pattern for PML-RARalpha is highly distinctive. Similarly, antibodies to the anaplastic lymphoma kinase (ALK) tyrosine kinase are valuable (because wild-type ALK is not found in normal lymphoid tissue) in detecting neoplasms (CD30-positive large T-cell lymphomas) with t(2;5) or its variants. Thus, immunocytochemical detection of the products of many rearranged genes in lymphoma and leukemia can be clinically informative and provide information on cellular and subcellular protein expression that cannot be inferred from studies based on messenger RNA.

Use of novel t(11;14) and t(14;18) dual-fusion fluorescence in situ hybridization probes in the differential diagnosis of lymphomas of small lymphocytes

Increasingly, molecular biologic techniques have become important in the diagnosis of non-Hodgkin lymphomas. In the differential diagnosis of lymphoma(s) of small lymphocytes (LSL), reliable detection of t(11;14) or t(14;18) would confirm the diagnosis of mantle cell lymphoma (MCL) or follicle center lymphoma (FCL), respectively. A total of 87 LSL cases (27 MCL, 39 FCL, 17 small lymphocytic lymphoma [SLL], 3 marginal zone lymphomas, and 1 paraimmunoblastic variant of SLL) were diagnosed by a combination of light microscopy, immunohistochemistry, and flow cytometric immunophenotyping. Interphase fluorescence in situ hybridization (FISH) for t(11;14) and t( 14;18) using dual-fusion probes (Vysis, Downers Grove, IL) was performed on touch (n = 69) or gravity (n = 18) preparations from these cases. Of 27 MCL cases tested, 25 (93%) had demonstrable t(11;14), none had t(14;18), and 2 were negative for t(11;14) and t(14;18). Twenty-five of 39 (64%) FCL cases had t(14;18), none had t(11;14), and the remaining FCL cases (14 cases [35%]) had neither t(11;14) nor t(14;18). All 17 (100%) SLL cases had neither t(11;14) nor t(14;18). All 3 (100%) marginal zone lymphoma cases had neither t(11;14) nor t(14;18). The case of paraimmunoblastic variant of SLL had t(11;14) and was negative for t(14;18). No discrepant [i.e., positive for both t(11;14) and t(14;18)] or false-positive cases were noted. Interphase FISH using these commercially available probes is a useful adjunct to light microscopy, immunohistochemistry, and flow cytometric immunophenotyping in the diagnosis of LSL. FISH can be performed successfully on archival single-cell preparations (touch preparations or gravity preparations) when fresh tissue is unavailable. No discordant or false-positive cases were identified.

Causes and consequences of BCL2 overexpression in diffuse large B-cell lymphoma

We investigated the frequency of bcl-2 protein overexpression in 80 diffuse large B-cell lymphoma (DLBCL) patients using both Western blotting and immunohistochemistry (IHC). Fifty-nine percent of the DLBCLs overexpressed bcl-2 protein by Western blot and 52% by IHC. The two methods usually gave concordant results (p=0.005), but 14 (21%) out of the 67 cases that were analyzed by both methods were positive by Western blot and negative by IHC, and 8 (12%) cases vice versa. Bcl-2 overexpression by IHC was associated with poor response to chemotherapy and poor survival, whereas these associations were not found when bcl-2 overexpression was determined by Western blotting. The molecular mechanisms leading to bcl-2 overexpression were evaluated by PCR, karyotype analysis, and comparative genomic hybridization (CGH). When studied by PCR and/or karyotype analysis, 12 (15%) of the 80 cases had translocation (14;18)(q32;q21). All 12 lymphomas with (14;18)(q32;q21) translocation had bcl-2 overexpression by Western blot as compared with 35 (51%) of the 68 lymphomas without translocation (p=0.001). Ten (29%) out of 34 cases that were analyzed by CGH showed amplification of chromosome 18 in which the BCL2 gene is located, and all cases showed bcl-2 overexpression by both Western blot and IHC. The results suggest that gene amplification and translocation are at least equally common mechanisms causing bcl-2 protein overexpression in DLBCL. Bcl-2 protein overexpression as determined by IHC is associated with poor response to chemotherapy and poor survival.

Rearrangements of bcl-1, bcl-2, bcl-6, and c-myc in diffuse large B-cell lymphomas

Diffuse large B-cell lymphoma (DLBL) is characterized by a marked degree of morphologic and clinical heterogeneity. We studied 137 patients with de novo DLBL for rearrangements of the bcl-1, bcl-2, bcl-6 and c-myc oncogenes by Southern blot analysis. Structural alterations of bcl-1, bcl-2, bcl-6, and c-myc were detected in 21 of 137 (15.3%), 8 of 137 (5.8%), 22 of 137 (16.1%), 14 of 137 (10.2%) patients, respectively. Two cases showed a combination of bcl-1 and bcl-6 rearrangements. Chromosomal analysis was performed in 31 cases of the 137 DLBL. 27 of these showed karyotypic abnormalities, and two had translocations 3q27 involving bcl-6. However, one of two cases had no rearrangement of bcl-6. Patients with rearranged bcl-6 and c-myc tended to have poorer survival than patients with germ-line. Furthermore, bcl-1 and bcl-2 rearrangements tended to have a better outcome, although the above differences were not statistically significant. Rearrangements of the bcl-1, 2, 6, and c-myc gene correlated with the clinical outcome in DLBL and may thus serve as prognostic markers in patients with this form of malignant lymphoma. However, other genetic factors are probably involved in determining prognosis.

Differential expression of BCL-2 family proteins in ALK-positive and ALK-negative anaplastic large cell lymphoma of T/null-cell lineage

Anaplastic large-cell lymphoma (ALCL) of T- or null-cell lineage, as defined in the revised European-American lymphoma classification, includes a subset of tumors that carry the t(2;5)(p23;q35) resulting in overexpression of anaplastic lymphoma kinase (ALK). Patients with ALK+ ALCL are reported to have a better prognosis than patients with ALK- ALCL. Because the mechanisms for this survival difference are unknown, we investigated the hypothesis that apoptotic pathways may be involved. We therefore assessed expression levels of the anti-apoptotic proteins BCL-2 and BCL-XL and the pro-apoptotic proteins BAX and BCL-XS in T/null-cell ALCL using immunohistochemical methods and correlated the findings with ALK expression and apoptotic rate (AR), the latter assessed by a modified Tdt-mediated dUTP nick-end labeling assay. ALK was detected in 21 of 66 (31.8%) ALCLs. BCL-2 was not detected in 21 ALK+ ALCLs but was present in 26 of 45 (57.8%) ALK- ALCLs (P < 0.0001). ALK+ and ALK- ALCLs also showed significant differences in expression of BCL-XL, BAX, and BCL-XS. ALK+ tumors less commonly had a high level of BCL-XL (1 of 17 versus 14 of 35, P = 0.01), and more commonly had high levels of BAX (13 of 18 versus 15 of 36, P = 0.05), and BCL-XS (11 of 16 versus 12 of 31, P = 0.05) compared with ALK- tumors. ALK+ tumors also had a higher mean AR than ALK- tumors (3.4% versus 1.1%, P = 0.0002). Differential expression of BCL-2 family proteins may be responsible for the higher AR observed in ALK+ ALCL and provides a possible biological explanation for the better prognosis reported for patients with ALK+ ALCL.