Clinical implications of phosphorylated STAT3 expression in De Novo diffuse large B-cell lymphoma

PURPOSE

Activated signal transducer and activator of transcription 3 (STAT3) regulates tumor growth, invasion, cell proliferation, angiogenesis, immune response, and survival. Data regarding expression of phosphorylated (activated) STAT3 in diffuse large B-cell lymphoma (DLBCL) and the impact of phosphorylated STAT3 (pSTAT3) on prognosis are limited.

EXPERIMENTAL DESIGN

We evaluated expression of pSTAT3 in de novo DLBCL using immunohistochemistry, gene expression profiling (GEP), and gene set enrichment analysis (GSEA). Results were analyzed in correlation with cell-of-origin (COO), critical lymphoma biomarkers, and genetic translocations.

RESULTS

pSTAT3 expression was observed in 16% of DLBCL and was associated with advanced stage, multiple extranodal sites of involvement, activated B-cell-like (ABC) subtype, MYC expression, and MYC/BCL2 expression. Expression of pSTAT3 predicted inferior overall survival (OS) and progression-free survival (PFS) in patients with de novo DLBCL. When DLBCL cases were stratified according to COO or MYC expression, pSTAT3 expression did not predict inferior outcome, respectively. Multivariate analysis showed that the prognostic predictability of pSTAT3 expression was due to its association with the ABC subtype, MYC expression, and adverse clinical features. GEP demonstrated upregulation of genes, which can potentiate function of STAT3. GSEA showed the JAK-STAT pathway to be enriched in pSTAT3(+) DLBCL.

CONCLUSIONS

The results of this study provide a rationale for the ongoing successful clinical trials targeting the JAK-STAT pathway in DLBCL.

Prevalence and clinical implications of epstein-barr virus infection in de novo diffuse large B-cell lymphoma in Western countries

PURPOSE

Epstein-Barr virus-positive (EBV(+)) diffuse large B-cell lymphoma (DLBCL) of the elderly is a variant of DLBCL with worse outcome that occurs most often in East-Asian countries and is uncommon in the Western hemisphere. We studied the largest cohort of EBV(+) DLBCL, independent of age, treated with rituximab combined with CHOP (R-CHOP) in developed Western countries.

EXPERIMENTAL DESIGN

A large cohort (n = 732) of patients with DLBCL treated with R-CHOP chemotherapy is included from the multicenter consortium. This study group has been studied for expression of different biomarkers by immunohistochemistry, genetic abnormalities by FISH and mutation analysis, genomic information by gene expression profiling (GEP), and gene set enrichment analysis (GSEA).

RESULTS

Twenty-eight patients (4.0%) were positive for EBV with a median age of 60.5 years. No clinical characteristics distinguished patients with EBV(+) DLBCL from patients with EBV-negative (EBV(-)) DLBCL. Genetic aberrations were rarely seen. NF-κB p50, phosphorylated STAT-3, and CD30 were more commonly expressed in EBV(+) DLBCLs (P < 0.05). Significant differences in survival were not observed in patients with EBV(+) DLBCL versus EBV(-) DLBCL. However, CD30 expression combined with EBV conferred an inferior outcome. GEP showed a unique expression signature in EBV(+) DLBCL. GSEA revealed enhanced activity of the NF-κB and JAK/STAT pathways independent of molecular subtype.

CONCLUSIONS

The clinical characteristics of patients with EBV(+) versus EBV(-) DLBCL are similar and EBV infection does not predict a worse outcome. EBV(+) DLBCL, however, has a unique genetic signature. CD30 expression is more common in EBV(+) DLBCL and, consistent CD30 and EBV is associated with an adverse outcome. Clin Cancer Res; 20(9); 2338-49. ©2014 AACR.

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.

Stromal endothelial cells establish a bidirectional crosstalk with chronic lymphocytic leukemia cells through the TNF-related factors BAFF, APRIL, and CD40L

Chronic lymphocytic leukemia (CLL) is a clonal B cell disorder of unknown origin. Accessory signals from the microenvironment are critical for the survival, expansion, and progression of malignant B cells. We found that the CLL stroma included microvascular endothelial cells (MVECs) expressing BAFF and APRIL, two TNF family members related to the T cell-associated B cell-stimulating molecule CD40L. Constitutive release of soluble BAFF and APRIL increased upon engagement of CD40 on MVECs by CD40L aberrantly expressed on CLL cells. In addition to enhancing MVEC expression of CD40, leukemic CD40L induced cleavases that elicited intracellular processing of pro-BAFF and pro-APRIL proteins in MVECs. The resulting soluble BAFF and APRIL proteins delivered survival, activation, Ig gene remodeling, and differentiation signals by stimulating CLL cells through TACI, BAFF-R, and BCMA receptors. BAFF and APRIL further amplified CLL cell survival by upregulating the expression of leukemic CD40L. Inhibition of TACI, BCMA, and BAFF-R expression on CLL cells; abrogation of CD40 expression in MVECs; or suppression of BAFF and APRIL cleavases in MVECs reduced the survival and diversification of malignant B cells. These data indicate that BAFF, APRIL, and CD40L form a CLL-enhancing bidirectional signaling network linking neoplastic B cells with the microvascular stroma.

Comprehensive gene expression profiling and immunohistochemical studies support application of immunophenotypic algorithm for molecular subtype classification in diffuse large B-cell lymphoma: a report from the International DLBCL Rituximab-CHOP Consortium Program Study

Gene expression profiling (GEP) has stratified diffuse large B-cell lymphoma (DLBCL) into molecular subgroups that correspond to different stages of lymphocyte development-namely germinal center B-cell like and activated B-cell like. This classification has prognostic significance, but GEP is expensive and not readily applicable into daily practice, which has lead to immunohistochemical algorithms proposed as a surrogate for GEP analysis. We assembled tissue microarrays from 475 de novo DLBCL patients who were treated with rituximab-CHOP chemotherapy. All cases were successfully profiled by GEP on formalin-fixed, paraffin-embedded tissue samples. Sections were stained with antibodies reactive with CD10, GCET1, FOXP1, MUM1 and BCL6 and cases were classified following a rationale of sequential steps of differentiation of B cells. Cutoffs for each marker were obtained using receiver-operating characteristic curves, obviating the need for any arbitrary method. An algorithm based on the expression of CD10, FOXP1 and BCL6 was developed that had a simpler structure than other recently proposed algorithms and 92.6% concordance with GEP. In multivariate analysis, both the International Prognostic Index and our proposed algorithm were significant independent predictors of progression-free and overall survival. In conclusion, this algorithm effectively predicts prognosis of DLBCL patients matching GEP subgroups in the era of rituximab therapy.

Clonal X-chromosome inactivation suggests that splenic cord capillary hemangioma is a true neoplasm and not a subtype of splenic hamartoma

Splenic hamartoma is a rare tumor-like lesion composed of structurally disorganized red pulp elements. It has been hypothesized that two other splenic lesions, cord capillary hemangioma and myoid angioendothelioma, may fall within the spectrum of splenic hamartoma, simply representing morphological variants. In this study, we compared the vascular and stromal composition of cord capillary hemangioma and myoid angioendothelioma with those of classical hamartoma. In addition, we assessed the clonal vs polyclonal nature of the lesions in nine female cases by performing clonality analysis for X-chromosome inactivation at the human androgen receptor locus (HUMARA) on laser-assisted microdissected samples. In 15 of 17 cases, increased reticulin and/or collagen content was observed. The classical hamartoma cases showed a vasculature predominantly composed of CD8+ CD31+ CD34- splenic sinuses, whereas cases of cord capillary hemangioma and myoid angioendothelioma contained many CD8- CD31+ CD34+ cord capillaries, but very little CD8+ vasculature. All cases lacked expression of D2-40 and Epstein Barr virus-encoded RNA. All cases showed a proliferation index of ≤5% by Ki-67. Cases of classical hamartoma lacked significant perisinusoidal expression of collagen IV and low-affinity nerve growth factor receptor. Both markers were variably expressed in the other lesions. Increased CD163-positive histiocytes were found in four cases (three cord capillary hemangiomas and one myoid angioendothelioma). HUMARA analysis was informative in all nine tested cases, of which three cases showed a non-random X-chromosome inactivation pattern, indicating clonality. All three clonal cases were cord capillary hemangiomas. Our study has shown that in spite of considerable morphologic heterogeneity and overlapping features, classical hamartoma and cord capillary hemangioma and myoid angioendothelioma are different in terms of their vascular and stromal composition. Clonality analysis supports a true neoplastic origin for the cord capillary hemangioma. A larger study using additional immunohistochemical and molecular studies is necessary to further evaluate the biological significance of the current findings.

Review of chromium (VI) apoptosis, cell-cycle-arrest, and carcinogenesis

Hexavalent chromium combines with glutathione in chloride intracellular channel carrier to form tetravalent and pentavalent chromium in plasma and organelle membranes. It also combines with NADH/NADPH to form pentavalent chromium in mitochondria. Tetravalent- and pentavalent- chromium (directly and indirectly) mediated DNA double strand breaks activate DNA damage signaling sensors: DNA-dependent-protein-kinase signals p53-dependent intrinsic mitochondrial apoptosis, and ataxia-telangiectasia-mutated and ataxia-telangiectasia-Rad3-related signal cell-arrest for DNA repair. Tetravalent chromium may be the most potent species since it causes DNA breaks and somatic recombination, but not apoptosis. Upon further failure of apoptosis and senescence/DNA-repair, damaged cells may become immortal with loss-of-heterozygosity and genetic plasticity.

A 42-year-old man with "pseudo-coprolalia"

A 42-year-old right-handed man presented with one week's history of uncharacteristic use of coarse language with associated anomia, inappropriate word usage and slowness of thoughts. Imaging demonstrated a solitary infarct involving the anterior left thalamus. Clinical and imaging findings and the current literature on anterior thalamic insult are discussed.

Diffuse blastoid B-cell lymphoma: a histologically aggressive variant of t(14;18)-negative follicular lymphoma

Among the diffuse lymphomas of B-cell origin, we have encountered one variant displaying blastoid features that morphologically mimic lymphoblastic lymphoma, the blastoid variant of mantle cell lymphoma, and the so-called blastoid transformation of follicular lymphoma. To better characterize this entity, we studied eight cases morphologically, immunohistochemically, and by fluorescence in situ hybridization (FISH) for cytogenetic abnormalities commonly associated with follicular lymphoma and B-cell lymphomas exhibiting high-grade histological features. All eight cases were presented as de novo neoplasms, and displayed an entirely diffuse (five cases) or only minimal follicular (three cases) growth pattern. The neoplastic lymphoid cells were of medium size with round nuclei, fine chromatin, inconspicuous nucleoli, and high mitotic rate; they expressed CD10, BCL6, and BCL2-a phenotype consistent with follicle center cell origin. A proportion of cases expressed MUM1. Their lack of TdT and CYCLIN D1 distinguished them from lymphoblastic lymphoma and the blastoid mantle cell lymphoma, respectively. The neoplastic lymphoid cells consistently expressed CD43 (seven of eight cases) and occasionally other T-cell-associated antigens, including CD5, CD7, CD8, and CD57. Although all cases overexpressed BCL2, t(14;18) was not detected in any of the five cases examined by FISH; instead, extra copies of chromosome 18 were found in four of five cases. Finally, other cytogenetic abnormalities, including structural abnormalities of BCL6 (allelic loss/gain, rearrangement), monosomy 7, del(13)(q14), and MYC allelic loss, were frequently detected. The combination of a B-cell CD10+ BCL6+ BCL2+ phenotype in the presence of structural abnormalities of BCL6 is consistent with a follicular center cell derivation for our cases. The lack of t(14;18) seen in our cases, although rare in most cases of follicular lymphoma, has been nevertheless reported in cases of follicular lymphoma with a predominantly diffuse growth pattern. The molecular pathogenesis, clinical manifestations, and prognostic significance of these lesions remain to be elucidated.

Immunophenotypic analysis of AIDS-related diffuse large B-cell lymphoma and clinical implications in patients from AIDS Malignancies Consortium clinical trials 010 and 034

PURPOSE

Diffuse large B-cell lymphoma (DLBCL) represents a clinically heterogeneous disease. Models based on immunohistochemistry predict clinical outcome. These include subdivision into germinal center (GC) versus non-GC subtypes; proliferation index (measured by expression of Ki-67), and expression of BCL-2, FOXP1, or B-lymphocyte-induced maturation protein (Blimp-1)/PRDM1. We sought to determine whether immunohistochemical analyses of biopsies from patients with DLBCL having HIV infection are similarly relevant for prognosis.

PATIENTS AND METHODS

We examined 81 DLBCLs from patients with AIDS in AMC010 (cyclophosphamide, doxorubicin, vincristine, and prednisone [CHOP] v CHOP-rituximab) and AMC034 (etoposide, doxorubicin, vincristine, prednisone, and dose-adjusted cyclophosphamide plus rituximab concurrent v sequential) clinical trials and compared the immunophenotype with survival data, Epstein-Barr virus (EBV) positivity, and CD4 counts.

RESULTS

The GC and non-GC subtypes of DLBCL did not differ significantly with respect to overall survival or CD4 count at cancer presentation. EBV could be found in both subtypes of DLBCL, although less frequently in the GC subtype, and did not affect survival. Expression of FOXP1, Blimp-1/PRDM1, or BCL-2 was not correlated with the outcome in patients with AIDS-related DLBCL.

CONCLUSION

These data indicate that with current treatment strategies for lymphoma and control of HIV infection, commonly used immunohistochemical markers may not be clinically relevant in HIV-infected patients with DLBCL. The only predictive immunohistochemical marker was found to be Ki-67, where a higher proliferation index was associated with better survival, suggesting a better response to therapy in patients whose tumors had higher proliferation rates.

The stromal composition of mast cell aggregates in systemic mastocytosis

Systemic mastocytosis is a stem cell disorder characterized histologically by the presence of multifocal compact aggregates of mast cells in at least one extracutaneous organ with or without evidence of skin lesions. The mast cell aggregates are accompanied by fibrosis, which is often significant. However, in spite of its frequent occurrence and severity, little is known about its characteristics. In this study, we evaluated the composition of the fibrotic mast cell aggregates by studying eight bone marrow biopsies and two spleens involved by systemic mastocytosis, and compared the findings with those observed in other fibrotic bone marrow disorders such as primary myelofibrosis and metastatic malignancy. Histochemistry and immunohistochemistry were used to evaluate: (a) extracellular matrix (reticulin, trichrome, collagen IV, laminin); (b) stromal reticulum cells (low-affinity nerve growth factor receptor); (c) presence of myofibroblastic differentiation (smooth muscle actin) and (d) microvessel density (CD34). We found that all cases showed marked reticulin and collagen fibrosis. However, unlike primary myelofibrosis and metastatic malignancy, which are usually associated with increased low-affinity nerve growth factor receptor positivity, its expression was low in all cases of systemic mastocytosis. Myofibroblastic differentiation was only focally detected in two of eight bone marrow biopsies. In all cases, the systemic mastocytosis lesions were largely devoid of type IV collagen and laminin. The latter findings were in contrast with those seen in cases of primary myelofibrosis and metastatic malignancy where smooth muscle actin, collagen IV and laminin were expressed in most cases. Also in contrast with the other two conditions, only minimal vascularity was detectable within the fibrotic mast cell lesions. These findings indicate that systemic mastocytosis exhibits a distinct pattern of stromal change, and suggest that the fibrogenetic mechanism in systemic mastocytosis is most likely different from that of other bone marrow neoplasms which are also associated with fibrosis.

Immunoglobulin D enhances immune surveillance by activating antimicrobial, proinflammatory and B cell-stimulating programs in basophils

Immunoglobulin D (IgD) is an enigmatic antibody isotype that mature B cells co-express with IgM through alternative RNA splicing. We found active T cell-dependent and T cell-independent IgM-to-IgD class switching in human upper respiratory mucosa B cells. This process required activation-induced cytidine deaminase and generated local and circulating IgD-producing plasmablasts reactive to respiratory bacteria. Circulating IgD bound to basophils through a calcium-mobilizing receptor that induced antimicrobial, opsonizing, inflammatory and B cell-stimulating factors including cathelicidin, interleukin-1, interleukin-4 and B cell-activating factor BAFF upon IgD cross-linking. By showing dysregulation of IgD class-switched B cells and IgD-armed basophils in autoinflammatory syndromes with periodic fever, our data indicate that IgD orchestrates an ancestral surveillance system at the interface between immunity and inflammation.

Viral double-stranded RNA triggers Ig class switching by activating upper respiratory mucosa B cells through an innate TLR3 pathway involving BAFF

Class switch DNA recombination (CSR) from IgM to IgG and IgA is crucial for antiviral immunity. Follicular B cells undergo CSR upon engagement of CD40 by CD40 ligand on CD4+ T cells. This T cell-dependent pathway requires 5-7 days, which is too much of a delay to block quickly replicating pathogens. To compensate for this limitation, extrafollicular B cells rapidly undergo CSR through a T cell-independent pathway that involves innate Ag receptors of the TLR family. We found that a subset of upper respiratory mucosa B cells expressed TLR3 and responded to viral dsRNA, a cognate TLR3 ligand. In the presence of dsRNA, mucosal B cells activated NF-kappaB, a transcription factor critical for CSR. Activation of NF-kappaB required TRIF (Toll/IL-1R domain-containing protein inducing IFN-beta), a canonical TLR3 adapter protein, and caused germline transcription of downstream CH genes as well as expression of AID (activation-induced cytidine deaminase), a DNA-editing enzyme essential for CSR. Subsequent IgG and IgA production was enhanced by BAFF (B cell-activating factor of the TNF family), an innate mediator released by TLR3-expressing mucosal dendritic cells. Indeed, these innate immune cells triggered IgG and IgA responses upon exposure to dsRNA. By showing active TLR3 signaling and ongoing CSR in upper respiratory mucosa B cells from patients with CD40 signaling defects, our findings indicate that viral dsRNA may initiate frontline IgG and IgA responses through an innate TLR3-dependent pathway involving BAFF.