Expression and pro-survival function of phospholipase Cγ2 in diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) can be cured in about 60% of cases with immuno-chemotherapy. However, a large subset of patients with DLBCL do not go into remission, or relapse after first-line therapy. Further therapy options are therefore needed. Phospholipase Cγ2 (PLCγ2) is one of the key regulators of the B cell receptor signaling pathway, which targets several pro-proliferative factors, such as nuclear factor κB (NFκB), Ras and Akt. Using immunohistochemistry, we found that PLCγ2 was strongly expressed in 63% of cases of DLBCL. The PLC inhibitor U73122 had an inhibitory effect on cell proliferation and induced apoptosis and G0/G1 cell cycle arrest. Co-treatment with enzastaurin or the Src inhibitor pp2 together with U73122 had an additive effect on cell proliferation compared to U73122 alone. Unexpectedly, strong PLCγ2 expression was associated with better overall survival. In conclusion, PLCγ2 is strongly expressed in a significant number of DLBCLs and has prognostic implications. Inhibition of PLCγ2 could be a new target for lymphoma treatment.

Loss of HLA-DR expression and immunoblastic morphology predict adverse outcome in diffuse large B-cell lymphoma - analyses of cases from two prospective randomized clinical trials.

BACKGROUND: Research on prognostically relevant immunohistochemical markers in diffuse large B-cell lymphomas has mostly been performed on retrospectively collected clinical data. This is also true for immunohistochemical classifiers that are thought to reflect the cell-of-origin subclassification of gene expression studies. In order to obtain deeper insight into the heterogeneous prognosis of diffuse large B-cell lymphomas and to validate a previously published immunohistochemical classifier, we analyzed data from a large set of cases from prospective clinical trials with long-term follow-up. DESIGN AND METHODS: We performed morphological and extensive immunohistochemical analyses in 414 cases of diffuse large B-cell lymphoma from two prospective randomized clinical trials (NHL-B1/B2, Germany). Classification into germinal center and non-germinal center subtypes of B-cell lymphoma was based on the expression pattern of CD10, BCL6, and IRF4. Multivariate analyses were performed adjusting for the factors in the International Prognostic Index. RESULTS: Analyzing 20 different epitopes on tissue microarrays, expression of HLA-DR, presence of CD23(+) follicular dendritic cell meshworks, and monotypic light chain expression emerged as International Prognostic Index-independent markers of superior overall survival. Immunoblastic morphology was found to be related to poor event-free survival. The non-germinal center subtype, according to the three-epitope classifier (CD10, BCL6, and IRF4) did not have prognostic relevance when adjusted for International Prognostic Index factors (relative risk=1.2, p=0.328 for overall survival; and relative risk=1.1, p=0.644 for event-free survival). CONCLUSIONS: The previously reported International Prognostic Index-independent prognostic value of stratification into germinal center/non-germinal center B-cell lymphoma using the expression pattern of CD10, BCL6, and IRF4 was not reproducible in our series. However, other markers and the morphological subtype appear to be of prognostic value.

Ki-67 as a prognostic marker in mantle cell lymphoma-consensus guidelines of the pathology panel of the European MCL Network.

Mantle cell lymphoma (MCL) has a heterogeneous clinical course and is mainly an aggressive B cell non-Hodgkin lymphoma; however, there are some indolent cases The Ki-67 index, defined by the percentage of Ki-67-positive lymphoma cells on histopathological slides, has been shown to be a very powerful prognostic biomarker. The pathology panel of the European MCL Network evaluated methods to assess the Ki-67 index including stringent counting, digital image analysis, and estimation by eyeballing. Counting of 2 × 500 lymphoma cells is the gold standard to assess the Ki-67 index since this value has been shown to predict survival in prospective randomized trials of the European MCL Network. Estimation by eyeballing and digital image analysis showed a poor concordance with the gold standard (concordance correlation coefficients [CCC] between 0.29 and 0.61 for eyeballing and CCC of 0.24 and 0.37 for two methods of digital image analysis, respectively). Counting a reduced number of lymphoma cells (2 × 100 cells) showed high interobserver agreement (CCC = 0.74). Pitfalls of the Ki-67 index are discussed and guidelines and recommendations for assessing the Ki-67 index in MCL are given.

Girls homozygous for an IL-2-inducible T cell kinase mutation that leads to protein deficiency develop fatal EBV-associated lymphoproliferation.

The fatal immune dysregulation that sometimes follows EBV infection in boys has been linked to mutations in two X chromosome-encoded genes, SLAM-associated protein (SAP) and X-linked inhibitor of apoptosis (XIAP). In this study we describe 2 girls from a consanguineous Turkish family who died after developing severe immune dysregulation and therapy-resistant EBV-positive B cell proliferation following EBV infection. SNP array-based genome-wide linkage analysis revealed IL-2-inducible T cell kinase (ITK) as a candidate gene for this immunodeficiency syndrome. Both girls harbored a homozygous missense mutation that led to substitution of a highly conserved residue (R335W) in the SH2 domain of ITK. Characteristics of ITK deficiency in mouse models, such as absence of NKT cells and high levels of eomesodermin in CD8+ cells, were seen in either one or both of the girls. Two lines of evidence suggested that R335W caused instability of the ITK protein. First, in silico modeling of the mutant protein predicted destabilization of the SH2 domain. Additionally, Western blot analysis revealed that, unlike wild-type ITK, the R335W mutant was nearly undetectable when expressed in 293 T cells. Our results suggest that ITK deficiency causes what we believe to be a novel immunodeficiency syndrome that leads to a fatal inadequate immune response to EBV. Because ITK deficiency resembles EBV-associated lymphoproliferative disorders in boys, we suggest that this molecular cause should be considered during diagnosis and treatment.

Expression profiling reveals specific gene expression signatures in gastric MALT lymphomas.

The purpose of this study is to identify genes that are involved in the etiology of Helicobacter pylori induced gastric MALT lymphoma. We compared gene expression profiles of gastric MALT lymphoma with their corresponding gastric MALT (chronic gastritis with formation of follicles and aggregates). cDNA microarrays were used to compare these two tissue types from the same patient (n = 21). Quantitative PCR and immunohistochemical staining were performed to validate the microarray results. Three hundred and fifty eight out of 11,552 genes were differentially expressed between gastric MALT lymphomas and gastric MALT. Thirty eight genes are implicated in immune response, 66 in signal transduction and 36 in cell proliferation. Interestingly, chromosome 6 was the only chromosome which was significantly over-represented with 25 genes (EASE score p = 0.01254). Several surface markers of haematopoietic cells, such as CD1c, CD40, CD44, CD53, CD83, CD86 and members of the HLA-D family were up-regulated in lymphoma tissues, indicating antigen-dependent survival of lymphoma cells. We conclude that gastric MALT lymphoma shows a specific gene expression profile, which allows the differentiation from H. pylori induced lymphoid gastritis.

Prevalence, clinical pattern, and outcome of CNS involvement in childhood and adolescent non-Hodgkin's lymphoma differ by non-Hodgkin's lymphoma subtype: a Berlin-Frankfurt-Munster Group Report.

PURPOSE: We analyzed the prevalence, clinical pattern, and prognostic impact of CNS involvement in a large cohort of children and adolescents diagnosed with non-Hodgkin's lymphoma (NHL), with special attention to differences according to NHL subtype. PATIENTS AND METHODS: From October 1986 to December 2002, 2,381 patients (median age, 9.37 years; range, 0.2 to 23.8 years; female-to-male ratio, 1:2.7) from Germany, Austria, and Switzerland were registered. A total of 2,086 patients were eligible for the consecutive multicenter protocols NHL-Berlin-Frankfurt-Münster [BFM] -86, NHL-BFM-90, and NHL-BFM-95, and could be evaluated for outcome. RESULTS: CNS involvement was diagnosed in 141 (5.9%) of 2,381 patients and was associated with an advanced stage of NHL. The percentage of CNS-positive patients was 8.8% for Burkitt's lymphoma/Burkitt's leukemia (BL/B-ALL), 5.4% for precursor B-lymphoblastic lymphoma (pB-LBL), 3.3% for anaplastic large-cell lymphoma, 3.2% for T-cell-LBL, 2.6% for diffuse large B-cell lymphoma, and 0% for primary mediastinal large B-cell NHL (P < .001). Most CNS-positive patients with pB-LBL, T-LBL, or BL/B-ALL had meningeal disease. The probability of event-free survival (pEFS; +/- SE) at 5 years was 85% +/- 1% for the 2,086 protocol patients (median follow-up, 6.5 years; range, 0.3 to 17.7 years). For the 112 CNS-positive patients, pEFS was 64% +/- 5%, compared with 86% +/- 1% for the 1,927 CNS-negative patients (P < .001). Although CNS disease had no impact on pEFS for advanced-stage T-LBL patients, CNS-positive patients with BL/B-ALL had a worse average outcome than CNS-negative patients with stage IV BL/B-ALL (60% +/- 5% v 81% +/- 3%; P < .001). In multivariate analysis, CNS disease was the strongest predictor for relapse in BL/B-ALL patients with advanced-stage disease. CONCLUSION: Six percent of childhood/adolescent NHL patients were CNS positive. However, the prevalence, pattern, and prognostic impact of CNS involvement differed among NHL subtypes.

Tumor sclerosis but not cell proliferation or malignancy grade is a prognostic marker in advanced-stage follicular lymphoma: the German Low Grade Lymphoma Study Group.

PURPOSE: Follicular lymphoma is an indolent lymphoma with a long median overall survival. However, a considerable number of patients die within the first 2 years after the onset of the disease. Because the treatment options vary with respect to antitumor effect and potential toxic adverse effects, the identification of high-risk patients would be helpful in directing therapeutic decisions in individual patients. Several histopathologic biomarkers for risk stratification have been suggested, but most markers have not been validated in patients treated in prospective trials. PATIENTS AND METHODS: We report a comprehensive approach to evaluate histopathologic biomarkers, including WHO grade, histology, and proliferation and quantitation of immune bystander cells, in 158 patients with nodal advanced-stage follicular lymphoma treated first line within a randomized trial. RESULTS: Tumor sclerosis was a significant prognostic marker of poor overall survival that was independent of the Follicular Lymphoma International Prognostic Index (FLIPI). WHO grade, proliferation, and total T-cell or macrophage content were not associated with overall survival. CONCLUSION: The presence of sclerosis within the lymphoma is a marker of poor overall survival that is independent of the FLIPI. The quantification of macrophage or absolute T-cell content, grading, and proliferation are of no help in predicting the outcome of FL. Future studies need to identify surrogate markers for the prognostic immune signatures identified by gene expression profiling. Most importantly, new prognostic markers need to be confirmed in patients treated within prospective trials.

A biologic definition of Burkitt's lymphoma from transcriptional and genomic profiling.

BACKGROUND: The distinction between Burkitt's lymphoma and diffuse large-B-cell lymphoma is unclear. We used transcriptional and genomic profiling to define Burkitt's lymphoma more precisely and to distinguish subgroups in other types of mature aggressive B-cell lymphomas. METHODS: We performed gene-expression profiling using Affymetrix U133A GeneChips with RNA from 220 mature aggressive B-cell lymphomas, including a core group of 8 Burkitt's lymphomas that met all World Health Organization (WHO) criteria. A molecular signature for Burkitt's lymphoma was generated, and chromosomal abnormalities were detected with interphase fluorescence in situ hybridization and array-based comparative genomic hybridization. RESULTS: We used the molecular signature for Burkitt's lymphoma to identify 44 cases: 11 had the morphologic features of diffuse large-B-cell lymphomas, 4 were unclassifiable mature aggressive B-cell lymphomas, and 29 had a classic or atypical Burkitt's morphologic appearance. Also, five did not have a detectable IG-myc Burkitt's translocation, whereas the others contained an IG-myc fusion, mostly in simple karyotypes. Of the 176 lymphomas without the molecular signature for Burkitt's lymphoma, 155 were diffuse large-B-cell lymphomas. Of these 155 cases, 21 percent had a chromosomal breakpoint at the myc locus associated with complex chromosomal changes and an unfavorable clinical course. CONCLUSIONS: Our molecular definition of Burkitt's lymphoma clarifies and extends the spectrum of the WHO criteria for Burkitt's lymphoma. In mature aggressive B-cell lymphomas without a gene signature for Burkitt's lymphoma, chromosomal breakpoints at the myc locus were associated with an adverse clinical outcome.

Diffuse large B-cell lymphoma in pediatric patients belongs predominantly to the germinal-center type B-cell lymphomas: a clinicopathologic analysis of cases included in the German BFM (Berlin-Frankfurt-Munster) Multicenter Trial.

Diffuse large B-cell lymphoma (DLBCL) in adults is a heterogeneous disease. Biologic subgroups of DLBCL with a favorable prognosis (germinal center B-cell-like, GCB) and with a poor prognosis (activated B-cell-like, ABC) have been defined by gene expression profiling and can be distinguished by immunohistochemistry. In contrast to their adult counterparts, children with DLBCL have an excellent prognosis. We analyzed 63 cases of DLBCL in pediatric patients by immunohistochemistry and fluorescence in situ hybridization (FISH) and found a striking predominance of a GCB subtype, which might explain the good clinical outcome in these lymphomas. Interestingly, FISH applied to 50 of these cases, as well as conventional cytogenetics available in 3 cases, revealed absence of the translocation t(14;18) involving the BCL2 gene, which is present in about 15% of adult GCB subtype DLBCL. Our data indicate that pediatric DLBCL differs from adult DLBCL and might comprise a biologically unique subgroup of DLBCL from which important insights into the pathogenesis and biology of this disease might be gained.

Lymphomas of the female genital tract: a study of 186 cases and review of the literature.

Malignant lymphomas in the female genital tract are rare, and those arising from this tissue system are extremely uncommon. Most pertinent reports lack clear references to the accepted classifications or failed to apply immunomarkers and molecular techniques for a reliable diagnosis. We analyzed a large group of patients with primary and secondary lymphomas of the female genital tract classified on the basis of the recent WHO consensus. A total of 186 patients with malignant lymphoma detected in the female genital tract were selected from the files of the Kiel Lymphoma Registry covering the period of 1974 to 2004. Stringent criteria were applied to separate systemic versus secondary lymphomas. All cases were reviewed on the basis of conventionally stained sections, relevant immunohistochemistry using the alkaline phosphatase/anti-alkaline phosphatase technique, and clinical information, as far as available. When required, gene rearrangement analysis was performed, including TCR-gamma chain gene and the three FR fragments of the IgG heavy chain gene. In addition, typical chromosomal translocations were detected by means of the FISH technique to verify the diagnosis, where needed. Thirty-seven percent of the cases were systemic lymphomas and 63% were mostly extranodal lymphomas primary to the female genital tract. The adnexa were involved in 87 cases, followed by uterine corpus in 23 cases, uterine cervix in 17 cases, portio in 9 cases, vagina in 11 cases, and vulva including clitoris in 8 cases. In 31 cases, two or more adjacent sites were involved. In both (primary and secondary) groups, the adnexa were the prevailing site of involvement. As expected, the overwhelming majority of cases were of B phenotype. The most frequent type of lymphoma proved to be diffuse large B-cell lymphoma, closely followed by follicular lymphoma, including all 3 grades of malignancy. Burkitt lymphoma showed a rather similar frequency. Marginal zone lymphoma occurred exclusively as primary lesions in the uterine mucosa. Lymphoplasmacytic lymphoma was restricted to the vulvo-vaginal area and occurred in women over 60 years of age. In conclusion, our study provides a thorough overview of various types of lymphoma affecting the female genital tract primarily or secondarily, which were classified on the basis of a widely accepted WHO classification. Although quite rare, our report should remind the pathologist of considering malignant lymphomas while reading biopsies taken from female genital organ.

Long-term survival following radiotherapy and cytarabine chemotherapy for sporadic primary central nervous system lymphoma.

PURPOSE: To analyze the long-term results following whole brain radiotherapy (WBRT) with sequential intrathecal (i.th.) cytosine arabinoside (Ara-C) +/- intravenous (i.v.) Ara-C in patients with primary central nervous system lymphoma (PCNSL). PATIENTS AND METHODS: 14 patients were treated between July 1987 and August 1995. All had sporadic PCNSL with proven histology of high-grade CNS lymphoma (twelve diffuse large-cell B-lymphomas, one lymphoblastic lymphoma, one large T-cell lymphoma). Patients were treated with two to four cycles of induction chemotherapy (40 mg/m2 Ara-C i.th.), four patients received additional Ara-C i.v. (150 mg/m2, d1-4). WBRT was administered using 1.8-Gy fractions. Intrathecal chemotherapy was planned afterwards in 4-week intervals for 6 months. Posttreatment neurocognitive evaluations were performed in two long-term survivors. RESULTS: Two of four patients who received i.v. and i.th. induction chemotherapy showed progressive disease, and irradiation was started immediately. Six of 14 patients received 50.4 Gy WBRT, four patients had WBRT up to 39.6 Gy followed by a 10.8-Gy boost. Five patients died early during therapy either due to a decline of the general medical condition or progressive disease. Median survival was 41 months (95% confidence interval: 6-79 months), survival at 3 and 5 years was 59% and 42%, respectively. Six patients survived for 3 years, two younger patients are still alive (> 12 years). They show only slightly impaired neurocognitive functions without clinical relevance. CONCLUSION: This WBRT-based protocol with i.th. meningeal prophylaxis using Ara-C +/- i.v. Ara-C yields substantial long-term survival with moderate toxicity. The value of i.v. chemotherapy is currently being investigated in prospective studies.

Typing the histogenetic origin of the tumor cells of lymphocyte-rich classical Hodgkin's lymphoma in relation to tumor cells of classical and lymphocyte-predominance Hodgkin's lymphoma.

Hodgkin's lymphoma (HL) is separated into the classical (c) and lymphocyte-predominance (lp) forms. Whereas classical Hodgkin-Reed/Sternberg (HRS) cells carry mutated immunoglobulin (Ig) gene rearrangements that are often "crippled" and lack intraclonal diversity, and are likely derived from preapoptotic germinal center (GC) B cells, the lymphocytic and histiocytic cells of lpHL are presumably derived from selected GC B cells and often show ongoing somatic hypermutation. The recently identified lymphocyte-rich classical (lrc) HL is characterized by HRS cells with the immunophenotype of classical HRS cells (CD30(+)CD15(+)CD20(-)CD45(-)) but an infiltrate similar to lpHL and a clinical behavior resembling lpHL. To identify the histogenetic origin of the HRS cells in lrcHL and to determine the relationship to the lymphoma cells of cHL and lpHL we characterized seven cases of lrcHL by immunohistochemistry and sequenced the rearranged Ig genes of single micromanipulated HRS cells. The expression patterns of BCL6, CD138, Oct2, and BOB1 in HRS cells of lrcHL showed differences to those of both cHL and lpHL. Analyses of rearranged Ig genes identified clonal HRS cell expansions carrying mutated Ig rearrangements without significant intraclonal diversity in all seven of the cases. In two cases crippling mutations, rendering originally functional V gene rearrangements nonfunctional, were observed. Thus, the mutation pattern of rearranged Ig genes of HRS cells in lrcHL is clearly different from those in lymphocytic and histiocytic cells of lpHL, and resembles the pattern in HRS cells of cHL, suggesting that HRS cells in lrcHL derive from (preapoptotic) GC B cells that silenced hypermutation. In one case in addition to the dominant HRS cell clone, CD30(+) EBV-infected HRS-like cells unrelated to the tumor clone were observed, suggesting development of an expanded population of EBV-harboring HRS-like cells in the microenvironment of HL.

Differential expression of cancer testis genes in histological subtypes of non-Hodgkin's lymphomas.

PURPOSE: The purpose of this study was to determine the potentialof cancer testis (CT) antigens as vaccines for non-Hodgkin's lymphomas (NHLs). EXPERIMENTAL DESIGN: Ninety-three specimens of NHLs were analyzed for their composite expression of eight CT genes (MAGE-3, MAGE-4, CT-7, HOM-MEL-40/SSX-2, SSX-1, SSX-4, HOM-TES-14/SCP-1, and HOM-TES-85). Thirty-nine of these specimens were also analyzed for their NY-ESO-1 expression. RESULTS: Only 1 of 7 cases of chronic lymphocytic leukemia expressed a CT gene (HOM-TES-14/SCP-1), and 10 follicular lymphomas were negative for all of the CT genes tested. In B-cell lymphomas, the most frequent expression of CT genes was observed in diffuse large-cell lymphomas (HOM-TES-14/SCP-1: 7 of 28; SSX-1: 5 of 28; CT-7: 2 of 28; and HOM-MEL-40/SSX-2 and HOM-TES-85: 1 of 28 positive cases). Only 1 of 8 Burkitt's and 1 of 7 lymphoblastic lymphomas expressed a CT gene (CT7 and HOM-TES-14/SCP-1, respectively). A majority (9 of 15) of T- NHLs (9 peripheral T-cell lymphomas, 2 lymphoblastic T-cell lymphomas, and 4 cases of AILD) expressed HOM-TES-14/SCP-1. CONCLUSIONS: HOM-TES-14/SCP-1, and to some degree SSX-1 and CT-7 might be candidates for lymphoma vaccine development. However, the identification of additional tumor-specific antigens with a frequent expression in lymphomas is warranted to allow for the development of widely applicable polyvalent lymphoma vaccines.

Cloning of a complementary DNA encoding the unique dendritic cell antigen Ki-M9.

Human sinus-lining cells (SLC) of the lymph node sinuses most probably represent accessory cells for the primary humoral immune response and have been shown to express a unique antigen recognized by the monoclonal antibody Ki-M9. To characterize this SLC-specific antigen further, a spleen cDNA library established in the expression vector lambda gt-11 was searched immunochemically for clones expressing the Ki-M9 antigen. Two recombinant phage clones revealed a cDNA with an open reading frame of 1666 bp encoding a 68-kDa protein. When fused with an expression vector that codes for the bacterial maltose-binding protein (MBP), the purified MBP-Ki-M9 fusion protein could be clearly detected by Western blot analysis. Furthermore, in situ hybridization with Ki-M9 cDNA as a probe confirmed the SLC-specific expression of the cloned cDNA. Additionally, Ki-M9 mRNA transcripts were detected in follicular dendritic reticulum cells of the secondary germinal centers, in a few cells of the perifollicular zone of the spleen, in some sinusoidal cells of liver, and in thymic reticular cells. A sequence database research revealed a strong homology to a murine cDNA. By applying non-radioactive in situ hybridization on mouse tissue, strong expression in SLC of the lymph node and metallophilic cells of the spleen in mouse tissue could be seen indicating that the Ki-M9 cDNA is highly conserved in the two species. Further computer analysis of the deduced amino acid sequence of the Ki-M9 antigen showed a large number of potential glycosylation sites and a PEST motive, which are characteristic for rapidly degraded membrane bound proteins and represent prerequisites for the function of this cell system in initiating the humoral immune response.