Immunohistochemical double-hit score is a strong predictor of outcome in patients with diffuse large B-cell lymphoma treated with rituximab plus cyclophosphamide, Doxorubicin, vincristine, and prednisone

PURPOSE Approximately 5% of diffuse large B-cell lymphomas (DLBCLs) are double-hit lymphomas (DHLs) with translocations of both MYC and BCL2. DHLs are characterized by poor outcome. We tested whether DLBCLs with high expression of MYC protein and BCL2 protein share the clinical features and poor prognosis of DHLs. PATIENTS AND METHODS Paraffin-embedded lymphoma samples from 193 patients with de novo DLBCL who were uniformly treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) were studied using immunohistochemistry for MYC, BCL2, CD10, BCL6, and MUM1/interferon regulatory factor 4, and fluorescent in situ hybridization (FISH) for MYC and BCL2. Results FISH analysis identified DHL in 6% of patients, who showed the expected poor overall survival (OS; P = .002). On the basis of immunohistochemical MYC and BCL2 expression, a double-hit score (DHS) was assigned to all patients with DLBCL. The DHS-2 group, defined by high expression of both MYC and BCL2 protein, comprised 29% of the patients. DHS 2 was significantly associated with lower complete response rate (P = .004), shorter OS (P < .001), and shorter progression-free survival (PFS; P < .001). The highly significant correlation with OS and PFS was maintained in multivariate models that controlled for the International Prognostic Index and the cell-of-origin subtype (OS, P < .001; PFS, P < .001). DHS was validated in an independent cohort of 116 patients who were treated with R-CHOP. CONCLUSION The immunohistochemical DHS defined a large subset of DLBCLs with double-hit biology and was strongly associated with poor outcome in patients treated with R-CHOP.     

Evaluation of interphase fluorescence in situ hybridization for the t(14;18)(q32;q21) translocation in the diagnosis of follicular lymphoma on fine-needle aspirates: a comparison with flow cytometry immunophenotyping

BACKGROUND: Diagnosing lymphoproliferative disorders on fine-needle aspiration (FNA) can be challenging due to variable cellularity and lack of architecture. Ancillary studies often are required for diagnosis. Follicular lymphoma (FL) is characterized by a monoclonal B-cell proliferation with coexpression of CD19/CD10 and a t(14;18)(q32;q21) reciprocal translocation, resulting in the immunoglobulin heavy chain/BCL-2 fusion gene. These features also can be found, with much lower frequency, in diffuse large B-cell lymphoma (DLBCL) of follicle center cell origin. The objective of the current study was to compare the accuracy in detecting FL and DLBCL of follicle center cell origin by interphase fluorescence in situ hybridization (I-FISH) versus flow cytometry immunophenotyping (FCM) on FNAs. METHODS: Concurrent testing by FISH for t(14;18)(q32;q21) and FCM was performed on 84 FNAs, including 40 FLs and 44 non-FLs (de novo DLBCLs, mantle cell lymphomas, small lymphocytic lymphomas/chronic lymphocytic leukemias [SLLs/CLLs], small B-cell lymphomas, and reactive lymphoid hyperplasias). The final diagnosis was rendered based on the combined information from cytomorphology, FCM, FISH, immunocytochemical staining for Ki-67, monoclonality for kappa and lambda light chains, and, if available, corresponding tissue biopsy, cytogenetic analysis, and polymerase chain reaction analysis. RESULTS: Among 40 FLs, FISH produced positive results for the t(14;18) translocation in 85.0%, negative results in 7.5%, and insufficient results in 7.5%; whereas, with FCM, 75% of cases exhibited a CD19-positive (CD19+)/CD10+ population (28 monoclonal, 2 nonclonal), 12.5% of cases exhibited a CD19+/CD10-negative population (3 monoclonal, 2 nonclonal), and 12.5% of cases were insufficient. All of nonclonal results from FCM and all of the insufficient results from FCM analysis exhibited unequivocal t(14;18) translocation by FISH. In contrast, the three negative results and the three insufficient results from FISH were monoclonal and CD19+/CD10+ on FCM. The results from FISH and FCM were concordant in 75% cases. Of 44 non-FLs, FISH produced positive results for the t(14;18) translocation in 5 DLBCLs and 2 SLLs/CLLs. The latter showed single fusion signals just above the cutoff level. All cases in the non-FL group that failed to show clonality or had insufficient results from FCM were DLBCLs. Among 17 DLBCLs, FISH detected a t(14;18) translocation in 29.4%, whereas FCM demonstrated a CD19+/CD10+ population in 23.5%. CONCLUSIONS: I-FISH for the t(14;18)(q32;q21) translocation provided high overall accuracy in detecting FLs on FNAs. This test can be used for diagnosing or monitoring FL on FNAs when cellularity is limited or when FCM results are noncontributory. For detecting a follicle center cell origin in DLBCLs, I-FISH for the t(14;18) translocation appeared to be slightly more sensitive than FCM for the CD19+/CD10+ immunophenotype.     

弥漫大B细胞性淋巴瘤中t(14;18)易位及BCL2表达的意义

  目的  探讨弥漫大B细胞性淋巴瘤(DLBCL)中t(14;18)易位及BCL2表达的意义。  方法  用石蜡包埋组织免疫组织化学法检测142例淋巴结、胃肠道和咽淋巴环等不同器官或部位发生的DLBCL中CD10、BCL6、MUM1和BCL2的抗原表达, 按免疫表型将DLBCL分成GCB-DLBCL和非GCB-DLBCL两个亚型; 聚合酶链反应(PCR)扩增75例淋巴结结内DLBCL新鲜组织中由t(14;18)易位所形成的MBR/JH和lnfr/JH重组基因。  结果  142例DLBCL中, 75例(52.8%)表达BCL2。分型为GCB-DLBCL的51例中, 18例(35.3%)表达BCL2;分型为非GCB-DLBCL的91例中, 57例(62.6%)表达BCL2, 两者阳性率比较有显著性差异(P=0.002)。同时, BCL2的表达阳性率按不同器官或部位发生的DLBCL作比较, 结果也存在显著性差异(P=0.01)。18.7%的淋巴结结内DLBCL中有t(14;18)易位, 阳性病例主要见于GCB-DLBCL之中。  结论  t(14;18)易位是GCB—DLBCL亚型的遗传学特征, BCL2表达在不同亚型和不同器官或部位发生的DLBCL中有显著性差异。      

BCL2 mutation spectrum in B‐cell non‐Hodgkin lymphomas and patterns associated with evolution of follicular lymphoma

BCL2 is a target of somatic hypermutation in t(14;18) positive and also in a small fraction of t(14;18) negative diffuse large B‐cell lymphoma (DLBCL), suggesting an aberrant role of somatic hypermutation (ASHM). To elucidate the prevalence of BCL2 mutations in lymphomas other than DLBCL, we Sanger‐sequenced the hypermutable region of the BCL2 gene in a panel of 69 mature B‐cell lymphomas, including Richter's syndrome DLBCL, marginal‐zone lymphomas, post‐transplant lymphoproliferative disorders, HIV‐associated and common‐variable immunodeficiency‐associated DLBCL, all known to harbour ASHM‐dependent mutations in other genes, as well as 16 t(14,18) negative and 21 t(14;18) positive follicular lymphomas (FLs). We also investigated the pattern of BCL2 mutations in longitudinal samples from 10 FL patients relapsing to FL or transforming to DLBCL (tFL). By direct sequencing, we found clonally represented BCL2 mutations in 2/16 (13%) of t(14;18) negative FLs, 2/16 (13%) HIV‐DLBCLs, 1/9 (11%) of Richter's syndrome DLBCL, 1/17 (6%) of post‐transplant lymphoproliferative disorders and 1/2 (50%) common‐variable immunodeficiency‐associated DLBCL. The proportion of mutated cases was significantly lower than in FLs carrying the t(14;18) translocation (15/21, 71%). However, the absence of t(14;18) by FISH or PCR and the molecular features of the mutations strongly suggest that BCL2 represents an additional target of ASHM in these entities. Analysis of the BCL2 mutation pattern in clonally related FL/FL and FL/tFL samples revealed two distinct scenarios of genomic evolution: (i) direct evolution from the antecedent FL clone, with few novel clonal mutations acquired by the tFL major clone, and (ii) evolution from a common mutated long‐lived progenitor cell, which subsequently acquired distinct mutations in the FL and in the relapsed or transformed counterpart. Copyright © 2014 John Wiley & Sons, Ltd.     

Clinical Impact of t(14;18) in Diffuse Large B-cell Lymphoma

Objective: Recent studies have suggested that t(14;18) is present in a significant proportion of diffuse large B-cell lymphomas (DLBCLs). However, the prognostic significance of this translocation and its relationship with BCL-2 protein expression remains controversial. Our study aimed to investigate the predictive power of t(14;18) and BCL-2 protein expression in the prognosis of DLBCLs. Methods: Biopsy specimens from 106 DLBCLs were analyzed using interphase fluorescence in situ hybridization (FISH). Immu...     

Diffuse large B-cell lymphoma after transformation from low-grade follicular lymphoma: morphological, immunohistochemical, and FISH analyses

Follicular lymphoma (FL) is one of the most common subtypes of non-Hodgkin lymphoma and frequently transforms to diffuse large B-cell lymphoma (DLBCL). To clarify some aspects of the natural history of FL, we retrospectively examined 43 consecutive patients who had DLBCL with pre- or coexisting FL grade 1 or 2. The patients comprised 22 men and 21 women with a median age of 53 years. Most of the patients (34/43) showed advanced-stage (III or IV) disease initially. We examined both FL and DLBCL components morphologically, immunohistochemically, and by interface fluorescence in situ hybridization (FISH: IGH/BCL2 fusion, BCL6 translocation ) analysis. Most of the DLBCLs were classified as the centroblastic subtype, with two exceptions of the anaplastic subtype. Immunohistochemical analysis of both the FL and DLBCL components revealed the following respective positivity rates: CD20 100%/100%, CD10 86%/66%, Bcl-2 96%/91%, Bcl-6 84%/88%, MUM1 16%/34%, CD30 0%/20%, CD138 0%/0%, and CD5 0%/3%. Loss of CD10 ( 6/36, 17% ) and gain of MUM1 ( 7/28, 25% ) and CD30 ( 5/21, 24% ) through transformation were not infrequent. High positivity rates for Bcl-2 and Bcl-6 were maintained throughout transformation. Among the DLBCLs, 84% were classified as the germinal center B-cell phenotype (GCB) and 16% as non-GCB in accordance with the criteria of Hans et al . IGH/BCL2 fusion was detected by FISH in 89% of FLs and 82% of DLBCLs. BCL6 translocation was detected in 1/6 (17%) DLBCLs without IGH/BCL2 fusion. Thus, although the morphological features and FISH results for DLBCL were consistent with transformed FL, the immunophenotype showed wide heterogeneity. ( Cancer Sci 2008; 99: 1760–1768)     

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.     

BCL2 overexpression in diffuse large B-cell lymphoma.

Translocation (14;18)(q32;q21), which is detected in 20-30% of diffuse large B-cell lymphomas (DLBCL), is regarded as a major mechanism for BCL2 protein overexpression. Nevertheless, BCL2 overexpression is not always caused by t(14;18), because it is often detected in lymphomas without BCL2 rearrangement. Recent studies have shown that increased expression of BCL2 may also result from BCL2 gene amplification in DLBCL. Similarly, it has been speculated that the mutations of the open reading frame might cause increased expression of BCL2 by affecting the interactions of BCL2 with other proteins. The results obtained from studies on the association of BCL2 protein overexpression with survival of DLBCL are controversial, although a correlation with decreased overall survival seems to exist. However, BCL2 rearrangement does not seem to have any major association with poor prognosis, but it is difficult to assess its true impact on prognosis due to differences in treatment and follow-up, and methodologies applied to study the BCL2 rearrangement. This review summarizes the BCL2 expression studies in DLBCL and discusses the prognostic relevance of BCL2 overexpression and its mechanisms.     

BCL2 mutations in diffuse large B-cell lymphoma

BCL2 is deregulated in diffuse large B-cell lymphoma (DLBCL) by the t(14;18) translocation, gene amplification and/or nuclear factor-κB signaling. RNA-seq data have recently shown that BCL2 is the most highly mutated gene in germinal center B-cell (GCB) DLBCL. We have sequenced BCL2 in 298 primary DLBCL biopsies, 131 additional non-Hodgkin lymphoma biopsies, 24 DLBCL cell lines and 51 germline DNAs. We found frequent BCL2 mutations in follicular lymphoma (FL) and GCB DLBCL, but low levels of BCL2 mutations in activated B-cell DLBCL, mantle cell lymphoma, small lymphocytic leukemia and peripheral T-cell lymphoma. We found no BCL2 mutations in GC centroblasts. Many mutations were non-synonymous; they were preferentially located in the flexible loop domain, with few in BCL2-homology domains. An elevated transition/transversions ratio supports that the mutations result from somatic hypermutation. BCL2 translocations correlate with, and are likely important in acquisition of, additional BCL2 mutations in GCB DLBCL and FL. DLBCL mutations were not independently associated with survival. Although previous studies of BCL2 mutations in FL have reported mutations to result in pseudo-negative BCL2 protein expression, we find this rare in de-novo DLBCL.     

FISH is better than BIOMED-2 PCR to detect IgH/BCL2 translocation in follicular lymphoma at diagnosis using paraffin-embedded tissue sections

The most common genetic aberration in follicular lymphoma (FL) is the t(14;18)(q32;q21) translocation that juxtaposes the antiapoptotic BCL2 gene with the promoter of the immunoglobulin heavy chain (IgH) gene. Our aim was to test the usefulness of two different techniques, fluorescence in situ hybridization (FISH) and PCR to detect t(14;18) in FL at diagnosis in paraffin-embedded tissue sections. A total of 51 patients diagnosed of FL were analyzed. FISH was performed with dual color dual fusion commercial probes (VYSIS) and in PCR experiments, the BIOMED-2 primers covering MBR, mcr and 3'MBR regions were applied. FISH showed positivity for the IgH/BCL2 translocation in 96% of patients and PCR in 59% of patients. FISH was able to detect variant translocations involving light chain Ig, or showing variant patterns such as deletions of the IgH portion involved in translocation. In 4% of cases, the IgH/BCL2 translocation was not detected by any of the two techniques tested. Our results show that FISH represents the best technique to detect t(14;18) at diagnosis.     

Prognostic impact of chromosomal alteration of 3q27 on nodal B-cell lymphoma: correlation with histology, immunophenotype, karyotype, and clinical outcome in 329 consecutive patients

Rearrangements involving the BCL6 gene are found in 30% of diffuse large B-cell lymphomas (DLBCLs). We evaluated the clinical characteristics and prognoses of patients with B-cell lymphoma carrying 3q27 translocations. Among the 59 patients having 3q27 translocation, 10.9% had follicular lymphoma (FL) and 23.1% had DLBCL. It is of interest that the prognostic significance was not found between FL and DLBCL with 3q27 translocations. Progression-free survival (PFS) rate was significantly higher in the FL patients with 3q27 translocation than in those with 18q21 translocation. PFS rate was significantly higher in the DLBCL patients with 3q27 translocation than in those with 18q21 translocation. These findings suggest that the presence of 3q27 translocation is a significant prognostic factor in DLBCL.     

bcl-2与bcl-6在弥漫性大B细胞淋巴瘤中表达的研究

 目的　从蛋白水平和基因水平研究bcl-2、bcl-6在弥漫性大B细胞淋巴瘤（DLBCL）的表达。方法　应用免疫组织化学EnVision法对73例DLBCL进行CD3、CD10、CD20、bcl-2、bcl-6、MUM-1的标记。应用荧光原位杂交（FISH）技术检测其中57例t（14;18）染色体异位bcl-2基因的异常情况和54例bcl-6基因所在的3q27染色体的断裂和扩增情况。结果　肿瘤细胞表达CD10、bcl-6、MUM-1、bcl-2的阳性率分别为15.1 %、38.4 %、71.2 % 、79.2 %。57例患者中16例（28.1 %）存在t（14;18）。bcl-2蛋白表达与免疫学亚型有相关性（P＝0.035）,t（14;18）与预后有相关性（P＝0.045）,t（14;18）与bcl-2蛋白表达无相关性（P＝0.710）。54例中3q27染色体断裂11例（20.4 %）,扩增14例（25.9 %）。bcl-6阳性表达较阴性者预后好（P＝0.041）。bcl-6与3q27断裂和扩增无相关性（均P＝1.000）。结论　bcl-2、bcl-6蛋白和基因表达是各自独立的事件,它们在DLBCL中的意义不同。bcl-2蛋白是与免疫学亚型相关的预后标志物,bcl-2阳性的GCB型预后较差;t（14;18）是独立预后事件,阳性者预后较差,对靶向治疗患者应检测t（14;18）;bcl-6蛋白的表达有助于DLBCL的预后判断,可作为独立的预后因子。3q27染色体断裂可能提示预后较差。     

Translocation t(14;18)/IGH‐BCL2 in gastrointestinal follicular lymphoma

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. Cancer 2011. © 2010 American Cancer Society.     

Clinical impact of t(14;18) in diffuse large B-cell lymphoma

Objective: Recent studies have suggested that t(14;18) is present in a significant proportion of diffuse large B-cell lymphomas (DLBCLs). However, the prognostic significance of this translocation and its relationship with BCL-2 protein expression remains controversial. Our study aimed to investigate the predictive power of t(14;18) and BCL-2 protein expression in the prognosis of DLBCLs. Methods: Biopsy specimens from 106 DLBCLs were analyzed using interphase fluorescence in situ hybridization (FISH). Immunophenotypic analysis of CD20, CD3, CD10, BCL-6, MUM1 and BCL-2 was performed by immunohistochemistry. SPSS 13.0 software was used for statistical analysis. Results: The t(14;18) was identified in 27 of 106 cases (25.5%). The percentages of tumor cells expressing CD10, BCL-6, MUM1 and BCL-2 were 21.7%, 26.4%, 56.6% and 73.6%, respectively. The presence of this translocation was significantly correlated with the expression of CD10 and immunophenotypic subtype (p<0.001). No association was observed between BCL-2 protein expression and the presence of t(14;18). Multivariate analysis confirmed that both t(14;18) and BCL-2 expression were significantly associated with survival. Moreover, patients with t(14;18) had worse prognosis, compared with those with BCL-2 expression (for overall survival: hazard ratio, 4.235; 95%CI, 2.153-8.329, p<0.001 vs. hazard ration, 2.743; 95%CI, 1.262-5.962, p=0.011). Conclusions: The t(14;18) is a useful prognostic tool for the evaluation of DLBCL immunophenotype and prognosis. The prognosis of GCB (germinal centre-like B cell) DLBCL patients should be made with the consideration of the presence of this translocation, and the detection of t(14;18) should be included as a routine diagnostic test in these cases.     

Diffuse large B-cell lymphoma of Waldeyer's ring has distinct clinicopathologic features: a GELA study

BackgroundDiffuse large B-cell lymphomas (DLBCLs) arising in specific extranodal sites have peculiar clinicopathologic features.Patients and methodsWe analyzed a cohort of 187 primary Waldeyer's ring (WR) DLBCLs retrieved from GELA protocols using anthracyclin-based polychemotherapy.ResultsMost patients (92%) had stage I–II disease. A germinal center B-cell-like (GCB) immunophenotype was observed in 61%, and BCL2 expression in 55%, of WR DLBCLs. BCL2, BCL6, IRF4 and MYC breakpoints were observed in, respectively, 3 of 42 (7%), 9 of 36 (25%), 2 of 26 (8%) and 4 of 40 (10%) contributive cases. A variable follicular pattern was evidenced in 30 of 68 (44%) large biopsy specimens. The 5-year progression-free survival (PFS) and the overall survival (OS) of 153 WR DLBCL patients with survival information were 69.5% and 77.8%, respectively. The GCB immunophenotype correlated with a better OS (P = 0.0015), while BCL2 expression predicted a worse OS (P = 0.037), an effect overcome by the GCB/non-GCB classification. Compared with matched nodal DLBCLs, WR DLBCLs with no age-adjusted international prognostic index factor disclosed a better 5-year PFS rate (77.5% versus 70.7%; P = 0.03).ConclusionsWR DLBCLs display distinct clinicopathologic features compared with conventional DLBCLs, with usual localized-stage disease, common follicular features and a high frequency of GCB immunophenotype contrasting with a low rate of BCL2 rearrangements. In addition, they seem to be associated with a better outcome than their nodal counterpart.     

Distinctive patterns of BCL6 molecular alterations and their functional consequences in different subgroups of diffuse large B-cell lymphoma.

Gene expression profiling of diffuse large B-cell lymphoma (DLBCL) has revealed biologically and prognostically distinct subgroups: germinal center B-cell-like (GCB), activated B-cell-like (ABC) and primary mediastinal (PM) DLBCL. The BCL6 gene is often translocated and/or mutated in DLBCL. Therefore, we examined the BCL6 molecular alterations in these DLBCL subgroups, and their impact on BCL6 expression and BCL6 target gene repression. BCL6 translocations at the major breakpoint region (MBR) were detected in 25 (18.8%) of 133 DLBCL cases, with a higher frequency in the PM (33%) and ABC (24%) subgroups than in the GCB (10%) subgroup. Translocations at the alternative breakpoint region (ABR) were detected in five (6.4%) of 78 DLBCL cases, with three cases in ABC and one case each in the GCB and the unclassifiable subgroups. The translocated cases involved IgH and non-IgH partners in about equal frequency and were not associated with different levels of BCL6 mRNA and protein expression. BCL6 mutations were detected in 61% of DLBCL cases, with a significantly higher frequency in the GCB and PM subgroups (>70%) than in the ABC subgroup (44%). Exon-1 mutations were mostly observed in the GCB subgroup. The repression of known BCL6 target genes correlated with the level of BCL6 mRNA and protein expression in GCB and ABC subgroups but not with BCL6 translocation and intronic mutations. No clear inverse correlation between BCL6 expression and p53 expression was observed. Patients with higher BCL6 mRNA or protein expression had a significantly better overall survival. The biological role of BCL6 in translocated cases where repression of known target genes is not demonstrated is intriguing and warrants further investigation.     

MYC translocation and/or BCL 2 protein expression are associated with poor prognosis in diffuse large B‐cell lymphoma

Genomic alterations and protein expression levels have been established as prognostic factors for survival in patients with diffuse large B‐cell lymphoma (DLBCL). In particular, double‐hit DLBCL (DHL), which exhibits translocations in MYC and BCL2 and/or BCL6, is known to be associated with a poor prognosis. However, the clinical significance of gene alterations and protein expression levels for MYC, B‐cell lymphoma (BCL)2, and BCL6 are unclear. In this study, we analyzed 61 adult patients diagnosed with DLBCL without DHL, who were treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone, or similar regimens. There were no differences in the distribution of MYC expression rates among the different MYC gene statuses. In log–rank tests, MYC translocation was a prognostic factor for overall survival (OS; P = 0.011), whereas BCL2 and BCL6 translocation were not prognostic indicators (P = 0.999 and P = 0.925, respectively). Although the expression levels of MYC and BCL6 were not significantly associated with OS, the expression of BCL2 was a prognostic factor for OS (P = 0.027). Furthermore, copy number gains in the MYC, BCL2, and BCL6 genes did not affect OS. MYC translocation (hazard ratio, 4.769; range, 1.518–14.98; P = 0.007) and BCL2 protein expression (hazard ratio, 3.072; range, 1.002–9.413; P = 0.049) were independent prognostic factors for survival in multivariate analyses. In conclusion, MYC translocation and BCL2 expression may need to be investigated at the initial diagnosis to predict prognosis in patients with DLBCL.