Immunohistochemical profiling based on Bcl-2, CD10 and MUM1 expression improves risk stratification in patients with primary nodal diffuse large B cell lymphoma

Profiling of diffuse large B-cell lymphoma by immunohistochemistry: identification of prognostic subgroups

Diffuse large B-cell lymphoma (DLBCL) is a frequent lymphoma subtype with a heterogeneous behavior and a variable response to conventional chemotherapy. This clinical diversity is believed to reflect differences in the molecular pathways leading to lymphomagenesis. In this study, we have analyzed pretreatment, diagnostic samples from 108 DLBCL by immunohistology for expression of four markers linked to germinal center B-cells (CD10, Bcl-6), postgerminal center B-cells (MUM1) and apoptosis (Bcl-2). The results indicate that both CD10 and Bcl-6 are favorable prognostic indicators, in contrast to Bcl-2, which is an adverse parameter. Furthermore, using two algorithms for distinction between low- and high-risk patients proposed by Hans et al. (Blood, 2004; 103:275) and Muris et al. (Journal of Pathology, 2006; 208:714), it is shown that both are useful for predicting outcome in DLBCL. However, in this report, the algorithm of Hans et al. was superior to that of Muris et al. These findings confirm and extend other studies and indicate that different prognostic subgroups of DLBCL can be distinguished by simple immunohistological investigations for a limited number of markers. Whether these groups are also relevant for individual treatment decisions will be important to investigate in prospective studies.

Small-molecule XIAP antagonist restores caspase-9 mediated apoptosis in XIAP-positive diffuse large B-cell lymphoma cells

Clinical outcome in patients with primary nodal diffuse large B-cell lymphomas (DLBCLs) is correlated with expression of inhibitors of the intrinsic apoptosis pathway, including X-linked inhibitor of apoptosis protein (XIAP). XIAP suppresses apoptosis through inhibiting active caspase-3, caspase-7, and caspase-9. In this study, we investigated to see if the small-molecule XIAP antagonist 1396-12 induces cell death in cultured lymphoma cells of patients with DLBCL. Treatment with this XIAP antagonist resulted in relief of caspase-3 inhibition and in induction of apoptosis in 16 of 20 tested DLBCL samples. Sensitivity to the XIAP antagonist was observed in both chemotherapy-refractory and -responsive DLBCL, but did not affect peripheral blood mononuclear cells and tonsil germinal-center B cells from healthy donors. XIAP antagonist-sensitive samples were characterized by high expression levels of XIAP, relatively low expression levels of Bcl-2, and by constitutive caspase-9 activation. These data indicate that the small-molecule XIAP antagonist can induce apoptosis in cultured DLBCL cells and therefore should be considered for possible development as a therapy for these patients. In vitro sensitivity to the XIAP antagonist can be predicted based on biological markers, suggesting the possibility of predefining patients most likely to benefit from XIAP antagonist therapy.

Absence of cyclin-D2 and Bcl-2 expression within the germinal centre type of diffuse large B-cell lymphoma identifies a very good prognostic subgroup of patients

AIMS

To validate and improve the existing algorithm (proposed by Hans et al.) to classify diffuse large B-cell lymphoma (DLBCL).

METHODS AND RESULTS

Tissue microarrays constructed from 81 patients with DLBCL were studied by immunohistochemistry for expression of CD10, Bcl-6, MUM1, Bcl-2, cyclin-D2, FOXP1 and PKC-gamma proteins. Cases were classified as either germinal centre B-like (GCB) or non-GC according to Hans et al. An alternative classification was also employed, in which cases positive for either CD10 or Bcl-6 were considered as a GC subgroup and cases negative for both CD10 and Bcl-6 were considered as a non-GC subgroup. GC was further subdivided into favourable GC (negative for both Bcl-2 and cyclin-D2) and unfavourable GC (positive for either Bcl-2 or cyclin-D2). The 5-year event-free survival (EFS) amongst patients classified as favourable GC versus 'others' was 49.5% and 7.3%, respectively (log rank P < 0.0001). Similarly, the 5-year overall survival (OS) amongst patients classified as favourable GC versus 'others' was 58.6% and 13.7%, respectively (log rank P = 0.0001). The difference in survival was independent of the international prognostic index.

CONCLUSIONS

In this group of patients the risk stratification based on the new algorithm was better than that proposed by Hans et al.

Molecular genetic analysis of haematological malignancies II: mature lymphoid neoplasms

Molecular genetic techniques have become an integral part of the diagnostic assessment for many lymphomas and other chronic lymphoid neoplasms. The demonstration of a clonal immunoglobulin or T cell receptor gene rearrangement offers a useful diagnostic tool in cases where the diagnosis is equivocal. Molecular genetic detection of other genomic rearrangements may not only assist with the diagnosis but can also provide important prognostic information. Many of these rearrangements can act as molecular markers for the detection of low levels of residual disease. In this review, we discuss the applications of molecular genetic analysis to the chronic lymphoid malignancies. The review concentrates on those disorders for which molecular genetic analysis can offer diagnostic and/or prognostic information.

Reclassification of 300 Primary Cutaneous B-Cell Lymphomas According to the New WHO–EORTC Classification for Cutaneous Lymphomas: Comparison With Previous Classifications and Identification of Prognostic Markers

Purpose

In the new WHO–European Organisation for Research and Treatment of Cancer (WHO-EORTC) classification for cutaneous lymphomas three major groups of primary cutaneous B-cell lymphoma (CBCL) are distinguished: primary cutaneous marginal zone B-cell lymphoma (PCMZL) and primary cutaneous follicle center lymphoma (PCFCL) with a good prognosis, and primary cutaneous large B-cell lymphoma, leg type (PCLBCL-LT), with an intermediate-level prognosis. This study aimed to assess the clinical significance of the new classification compared with previous classification schemes (EORTC 1997; WHO 2001) and to define prognostic factors within the newly defined categories.

Patients and Methods

In the present study clinical data and histologic sections of 300 patients with CBCL, formerly classified according to the EORTC classification, were reviewed and reclassified according to the WHO and the new WHO-EORTC classification schemes.

Results

After reclassification, the study comprised 71 patients with PCMZL, 171 patients with PCFCL, and 58 patients with PCLBCL-LT, showing 5-year disease-specific survivals of 98%, 95%, and 50%, respectively. When compared with the EORTC and WHO schemes, 5.3% and 36.3% of patients with CBCL were reclassified into another prognostic category. Multivariate analysis of PCFCL revealed localization on the leg and expression of FOXP1 as independent parameters associated with a poor prognosis. Expression of Bcl-2 or MUM-1 had no significant effect on survival in this group. In PCLBCL-LT, no independent prognostic parameters were found.

Conclusion

These results emphasize the clinical significance of the WHO-EORTC classification, but suggest that within the group of PCFCL, distinction should be made between lymphomas presenting on the legs and lymphomas presenting at other sites.

The GCB subtype of diffuse large B-cell lymphoma is less frequent in Asian countries

Patients with the germinal center B-cell-like (GCB) subtype of diffuse large B-cell lymphoma (DLBCL) have a significantly better survival rate than those with non-GCB DLBCL. Several studies have examined the proportions of GCB and non-GCB subtypes in large series of DLBCL patients, but it remains unclear if these proportions are the same in different countries. We performed an immunohistochemical analysis of the numbers of GCB and non-GCB subtypes in a large number of patients with DLBCL in Japan and compared the results with literature data for other countries. We found that 71 of 248 patients (29%) had the GCB phenotype and 177 patients (71%) had the non-GCB subtype of DLBCL among our patient population. Assessment of data collected from other studies showed that 31% of DLBCL patients (102/330) have the GCB subtype in Asian countries, but 50% (206/416) express GCB phenotypes in Western countries; based on these data, the occurrence of the GCB subtype of DLBCL was significantly less in Asian countries (p<0.001). Since patients with the GCB phenotype of DLBCL have better survival, future studies of DLBCL should recognize the difference in the proportions of GCB and non-GCB subtypes of DLBCL between Asian and Western populations.

New prognostic relevant factors in primary cutaneous diffuse large B-cell lymphomas

BACKGROUND

There is a growing body of literature that has enhanced our understanding of the biology of primary cutaneous diffuse large B-cell lymphoma (PCDLBCL) including in the context of gene profiling studies. Recent studies have demonstrated an activated proliferation profile associated with leg type lymphoma including overexpression of proto-oncogenes PIM1, PIM2, and cMYC, and the transcription factors MUM1 and OCT2. Although gene profiling is very useful in understanding the molecular basis of diffuse large B-cell lymphoma (LBCL), it is not practical from a routine diagnostic perspective. In this regard, the purpose of the study was to further define an armamentarium of easily applied immunohistochemical stains to accurately prognosticate PCDLBCL.

METHODS

In all, 35 patients with PCDLBCL, 14 of follicle center and 21 of leg type, were analyzed using antibodies against CD5, CD138, BCL2, BCL6, OCT2, MUM1, FOXP1, and cMYC. Findings were correlated with clinical data.

RESULTS

All cases stained negative for CD5 and CD138. Both subtypes differed in distinct staining patterns for BCL6, BCL2, OCT2, MUM1, and FOXP1. Staining for BCL2, OCT2, and/or MUM1 was associated with poor, and BCL6 with a favorable prognosis. Expression of cMYC was irrespective of prognosis or subtype, whereas ulceration or primary manifestation on the leg or multiple lesions was indicative for worse prognosis.

LIMITATIONS

Case number was a limitation.

CONCLUSION

Discriminating PCDLBCL supports the validity of the World Health Organization/European Organization for Research and Treatment of Cancer classification. To identify risk factors in patients with PCDLBCL we recommend thorough evaluation of clinical presentation and exploratory staining pattern for BCL2, BCL6, MUM1 and OCT2.

IRF-4 and c-Rel expression in antiviral-resistant adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is a generally fatal malignancy. Most ATLL patients fare poorly with conventional chemotherapy; however, antiviral therapy with zidovudine (AZT) and interferon alpha (IFN-alpha) has produced long-term clinical remissions. We studied primary ATLL tumors and identified molecular features linked to sensitivity and resistance to antiviral therapy. Enhanced expression of the proto-oncogene c-Rel was noted in 9 of 27 tumors. Resistant tumors exhibited c-Rel (6 of 10; 60%) more often than did sensitive variants (1 of 9; 11%). This finding was independent of the disease form. Elevated expression of the putative c-Rel target, interferon regulatory factor-4 (IRF-4), was observed in 10 (91%) of 11 nonresponders and in all tested patients with c-Rel+ tumors and occurred in the absence of the HTLV-1 oncoprotein Tax. In contrast, tumors in complete responders did not express c-Rel or IRF-4. Gene rearrangement studies demonstrated the persistence of circulating T-cell clones in long-term survivors maintained on antiviral therapy. The expression of nuclear c-Rel and IRF-4 occurs in the absence of Tax in primary ATLL and is associated with antiviral resistance. These molecular features may help guide treatment. AZT and IFN-alpha is a suppressive rather than a curative regimen, and patients in clinical remission should remain on maintenance therapy indefinitely.

New transcription factors in diagnostic hematopathology

The transcription factors (TFs) that controls the intricate machinery of multistep differentiation and activation programs of the lymphoid system, represent a complex array of proteins, whose identification and function has only in part been completed. TFs are usually expressed during specific differentiation or activation cellular programs, making them interesting tools in diagnostic immunohistochemistry. In fact, the specificity of some of these TFs for lineage or activation/differentiation passages or their abnormal expression in specific disease entity, represents a feature that has been exploited in diagnostic/prognostic immunohistochemistry. Bcl-6 was the prototype of this class of markers. Currently, the expanding knowledge of the TFs involved in the differentiation programs and in the activation processes of T-lymphocyte and B-lymphocyte in normal and neoplastic conditions and the availability of antibodies able to efficiently recognize these TFs in histologic material, represent a powerful tool in diagnostic hematopathology. In this review we will consider the basic biologic aspects and the applications in hematopathology of some of the lymphocyte-related TFs, including Pax5/BSAB, MUM1/IRF4, BOB1, Oct-2, T-bet, and FOXP3. This field is rapidly evolving, as witnessed by the ongoing growing number of novel TFs with possible diagnostic applications appearing in the literature.

Profiling of apoptosis genes allows for clinical stratification of primary nodal diffuse large B-cell lymphomas

Intrinsic resistance of lymphoma cells to apoptosis is a probable mechanism causing chemotherapy resistance and eventual fatal outcome in patients with diffuse large B cell lymphomas (DLBCL). We investigated whether microarray expression profiling of apoptosis related genes predicts clinical outcome in 46 patients with primary nodal DLBCL. Unsupervised cluster analysis using genes involved in apoptosis (n = 246) resulted in three separate DLBCL groups partly overlapping with germinal centre B-lymphocytes versus activated B-cells like phenotype. One group with poor clinical outcome was characterised by high expression levels of pro-and anti-apoptotic genes involved in the intrinsic apoptosis pathway. A second group, also with poor clinical outcome, was characterised by high levels of apoptosis inducing cytotoxic effector genes, possibly reflecting a cellular cytotoxic immune response. The third group showing a favourable outcome was characterised by low expression levels of genes characteristic for both other groups. Our results suggest that chemotherapy refractory DLBCL are characterised either by an intense cellular cytotoxic immune response or by constitutive activation of the intrinsic mediated apoptosis pathway with concomitant downstream inhibition of this apoptosis pathway. Consequently, strategies neutralising the function of apoptosis-inhibiting proteins might be effective as alternative treatment modality in part of chemotherapy refractory DLBCL.

Diffuse large B-cell lymphoma: a heterogeneous group of non-Hodgkin lymphomas comprising several distinct clinicopathological entities

Diffuse large B-cell lymphoma (DLBCL) as defined by the World Health Organization (WHO) classification is clinically, morphologically and genetically a heterogeneous group of malignant proliferations of large lymphoid B cells. Over the last 6 years, several studies have been published improving our understanding of these lymphomas. These studies analyzed DLBCL by their gene expression profile, provided further information on some of the variants of DLBCL listed in the WHO classification and stressed the impact of the site of origin of these tumors. This review summarizes these recent data and explores their impact on the recognition of new clinicopathological lymphoma entities.

Prognostic immunohistologic markers in human tumors: why are so few used in clinical practice?

Technological advances in gene cloning and genome-wide analyses have greatly increased the number of new tumor markers that can be detected by immunohistologic techniques. While many of these have been evaluated with respect to prognosis, there is a striking discrepancy between the number of markers reported to confer prognostic information and those that are used in clinical practice. We argue that lessons learned from epidemiological studies are applicable to studies of immunohistologic markers; in particular, advances in both fields can be vitiated by non-causal associations. We suggest that the most valuable immunohistologic markers are those that reflect genetic abnormalities, that are linked to the cell of origin, or that reflect tumor infiltrating cells or stromal reactions. It should also be appreciated that a marker that is genuinely predictive of prognosis may nevertheless not find any application in clinical practice if it becomes obsolete through the introduction of newer therapies or because there is no choice of alternative treatment strategies.

Expression of the polycomb-group gene BMI1 is related to an unfavourable prognosis in primary nodal DLBCL

BACKGROUND

Clinical outcome in patients with diffuse large B cell lymphomas (DLBCL) is highly variable and poorly predictable. Microarray studies showed that patients with DLBCL with a germinal centre B cell-like (GCB) phenotype have a better prognosis than those with an activated B cell-like (ABC) phenotype. The BMI1 proto-oncogene was identified as one of the genes present in the signature of the ABC type of DLBCL, associated with a poor prognosis.

OBJECTIVES

(1) To investigate, in primary nodal DLBCL, the expression of BMI1 and its association with clinical outcome and DLBCL signature; (2) to look for an association between BMI1 expression and the expression of its putative downstream targets p14ARF and p16INK4a.

RESULTS

BMI1 expression was found to be associated with poor clinical outcome, but not clearly with an ABC-like phenotype of DLBCL. Expression of BMI1 was frequently, but not always, related to low levels of expression of p14ARF and p16INK4a.

CONCLUSION

Expression of BMI1 is associated with an unfavourable clinical outcome of primary nodal DLBCL.

Apoptosis resistance and response to chemotherapy in primary nodal diffuse large B-cell lymphoma

Diffuse large B-cell lymphomas (DLBCL) represent the most common type of adult malignant lymphoma in western countries and are treated with high dose combination chemotherapy. Although initially the majority of patients respond to this therapy, many do not achieve complete remission and others experience an early relapse. Several studies have shown that prediction of the clinical response to chemotherapy is possible before the start of chemotherapy treatment. Apparently, DLBCL are intrinsically either resistant or sensitive to chemotherapy-induced cell death. Differences in functional integrity of the apoptosis cascade are an important factor predicting outcome in DLBCL. In this review we discuss the possible mechanisms leading to intrinsic resistance to apoptosis and provide an explanation why strong differences in apoptosis sensitivity between DLBCL are observed. Subsequently we will focus on how differences in this intrinsic apoptosis resistance provide an explanation for the variable response to combination chemotherapy and how this can be used for further therapy tailoring.