Epstein-Barr virus-associated posttransplant lymphoproliferative disorders: new insights in pathogenesis, classification and treatment.

PURPOSE OF REVIEW: Posttransplant lymphoproliferative disorder (PTLD) is a serious complication following transplantation from an allogeneic donor. Epstein-Barr Virus (EBV) is involved in a substantial number of cases. In this review, we aim to summarize recent knowledge on pathogenesis, classification and treatment of EBV + PTLD. RECENT FINDINGS: New insights in the complex oncogenic properties of EBV antigens noncoding Ribonucleic acids (RNAs), especially EBV MicroRNA (miRNAs), have increased our knowledge of the pathogenesis of EBV + PTLD. In addition the potential influence of EBV on the tumor microenvironment is becoming clearer, paving the way for new types of immunotherapy. Currently PTLD is classified according to the World Health Organization classification together with other lymphoproliferative disorders, based on the specific immunosuppression. However, a new framework integrating all types of lymphoproliferative disorders in all different settings of immune deficiency and dysregulation is needed. Although treatment of EBV + and EBV - PTLD was largely similar in the past, EBV-directed therapies are currently increasingly used. SUMMARY: The use of EBV-directed therapies and new agents, based on better understanding of pathogenesis and classification of PTLD, will change the treatment landscape of EBV + PTLD in the next era.

Conditional expression of HGAL leads to the development of diffuse large B-cell lymphoma in mice.

Diffuse large B-cell lymphomas (DLBCLs) are clinically and genetically heterogeneous tumors. Deregulation of diverse biological processes specific to B cells, such as B-cell receptor (BCR) signaling and motility regulation, contribute to lymphomagenesis. Human germinal center associated lymphoma (HGAL) is a B-cell-specific adaptor protein controlling BCR signaling and B lymphocyte motility. In normal B cells, it is expressed in germinal center (GC) B lymphocytes and promptly downregulated upon further differentiation. The majority of DLBCL tumors, primarily GC B-cell types, but also activated types, express HGAL. To investigate the consequences of constitutive expression of HGAL in vivo, we generated mice that conditionally express human HGAL at different stages of hematopoietic development using 3 restricted Cre-mediated approaches to initiate expression of HGAL in hematopoietic stem cells, pro-B cells, or GC B cells. Following immune stimulation, we observed larger GCs in mice in which HGAL expression was initiated in GC B cells. All 3 mouse strains developed DLBCL at a frequency of 12% to 30% starting at age 13 months, leading to shorter survival. Immunohistochemical studies showed that all analyzed tumors were of the GC B-cell type. Exon sequencing revealed mutations reported in human DLBCL. Our data demonstrate that constitutive enforced expression of HGAL leads to DLBCL development.

Prognostic Significance of MYC Rearrangement and Translocation Partner in Diffuse Large B-Cell Lymphoma: A Study by the Lunenburg Lymphoma Biomarker Consortium.

PURPOSE: MYC rearrangement (MYC-R) occurs in approximately 10% of diffuse large B-cell lymphomas (DLBCLs) and has been associated with poor prognosis in many studies. The impact of MYC-R on prognosis may be influenced by the MYC partner gene (immunoglobulin [IG] or a non-IG gene). We evaluated a large cohort of patients through the Lunenburg Lymphoma Biomarker Consortium to validate the prognostic significance of MYC-R (single-, double-, and triple-hit status) in DLBCL within the context of the MYC partner gene. METHODS: The study cohort included patients with histologically confirmed DLBCL morphology derived from large prospective trials and patient registries in Europe and North America who were uniformly treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone therapy or the like. Fluorescence in situ hybridization for the MYC, BCL2, BCL6, and IG heavy and light chain loci was used, and results were correlated with clinical outcomes. RESULTS: A total of 5,117 patients were identified of whom 2,383 (47%) had biopsy material available to assess for MYC-R. MYC-R was present in 264 (11%) of 2,383 patients and was associated with a significantly shorter progression-free and overall survival, with a strong time-dependent effect within the first 24 months after diagnosis. The adverse prognostic impact of MYC-R was only evident in patients with a concurrent rearrangement of BCL2 and/or BCL6 and an IG partner (hazard ratio, 2.4; 95% CI, 1.6 to 3.6; P < .001). CONCLUSION: The negative prognostic impact of MYC-R in DLBCL is largely observed in patients with MYC double hit/triple-hit disease in which MYC is translocated to an IG partner, and this effect is restricted to the first 2 years after diagnosis. Our results suggest that diagnostic strategies should be adopted to identify this high-risk cohort, and risk-adjusted therapeutic approaches should be refined further.

Unifying mechanism for different fibrotic diseases.

Fibrotic diseases are not well-understood. They represent a number of different diseases that are characterized by the development of severe organ fibrosis without any obvious cause, such as the devastating diseases idiopathic pulmonary fibrosis (IPF) and scleroderma. These diseases have a poor prognosis comparable with endstage cancer and are uncurable. Given the phenotypic differences, it was assumed that the different fibrotic diseases also have different pathomechanisms. Here, we demonstrate that many endstage fibrotic diseases, including IPF; scleroderma; myelofibrosis; kidney-, pancreas-, and heart-fibrosis; and nonalcoholic steatohepatosis converge in the activation of the AP1 transcription factor c-JUN in the pathologic fibroblasts. Expression of the related AP1 transcription factor FRA2 was restricted to pulmonary artery hypertension. Induction of c-Jun in mice was sufficient to induce severe fibrosis in multiple organs and steatohepatosis, which was dependent on sustained c-Jun expression. Single cell mass cytometry revealed that c-Jun activates multiple signaling pathways in mice, including pAkt and CD47, which were also induced in human disease. αCD47 antibody treatment and VEGF or PI3K inhibition reversed various organ c-Jun-mediated fibroses in vivo. These data suggest that c-JUN is a central molecular mediator of most fibrotic conditions.

Gray zones around diffuse large B cell lymphoma. Conclusions based on the workshop of the XIV meeting of the European Association for Hematopathology and the Society of Hematopathology in Bordeaux, France.

The term "gray-zone" lymphoma has been used to denote a group of lymphomas with overlapping histological, biological, and clinical features between various types of lymphomas. It has been used in the context of Hodgkin lymphomas (HL) and non-Hodgkin lymphomas (NHL), including classical HL (CHL), and primary mediastinal large B cell lymphoma, cases with overlapping features between nodular lymphocyte predominant Hodgkin lymphoma and T-cell/histiocyte-rich large B cell lymphoma, CHL, and Epstein-Barr-virus-positive lymphoproliferative disorders, and peripheral T cell lymphomas simulating CHL. A second group of gray-zone lymphomas includes B cell NHL with intermediate features between diffuse large B cell lymphoma and classical Burkitt lymphoma. In order to review controversial issues in gray-zone lymphomas, a joint Workshop of the European Association for Hematopathology and the Society for Hematopathology was held in Bordeaux, France, in September 2008. The panel members reviewed and discussed 145 submitted cases and reached consensus diagnoses. This Workshop summary is focused on the most controversial aspects of gray-zone lymphomas and describes the panel's proposals regarding diagnostic criteria, terminology, and new prognostic and diagnostic parameters.

Paraffin-based 6-gene model predicts outcome in diffuse large B-cell lymphoma patients treated with R-CHOP.

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease characterized by variable clinical outcomes. Outcome prediction at the time of diagnosis is of paramount importance. Previously, we constructed a 6-gene model for outcome prediction of DLBCL patients treated with anthracycline-based chemotherapies. However, the standard therapy has evolved into rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP). Herein, we evaluated the predictive power of a paraffin-based 6-gene model in R-CHOP-treated DLBCL patients. RNA was successfully extracted from 132 formalin-fixed paraffin-embedded (FFPE) specimens. Expression of the 6 genes comprising the model was measured and the mortality predictor score was calculated for each patient. The mortality predictor score divided patients into low-risk (below median) and high-risk (above median) subgroups with significantly different overall survival (OS; P = .002) and progression-free survival (PFS; P = .038). The model also predicted OS and PFS when the mortality predictor score was considered as a continuous variable (P = .002 and .010, respectively) and was independent of the IPI for prediction of OS (P = .008). These findings demonstrate that the prognostic value of the 6-gene model remains significant in the era of R-CHOP treatment and that the model can be applied to routine FFPE tissue from initial diagnostic biopsies.

Expression of HGAL in primary cutaneous large B-cell lymphomas: evidence for germinal center derivation of primary cutaneous follicular lymphoma.

The classification of primary cutaneous large B-cell lymphoma (PCLBCL) is based on standard morphology, immunohistochemistry, and clinical presentation. There are two major subtypes in the current WHO-EORTC classification: follicle center lymphoma and diffuse large B-cell lymphoma, leg-type (DLBCL-LT). The goals of this study were to examine a series of DLBCLs to determine (1) whether the immunohistochemical paradigm of germinal center B-cell and non-germinal center B-cell types of systemic DLBCL could be applied to PCLBCL; (2) whether application of the newly described germinal center B-cell marker, human germinal center-associated lymphoma (HGAL) also discriminates between these types as a further support for germinal center B-cell origin for primary cutaneous center lymphoma; and (3) whether any of these biologic markers were of prognostic significance. To this end, 32 cases of diffuse PCLBCL (22 primary cutaneous follicular center lymphomas and 10 DLBCL-LT) were classified based on the WHO-EORTC criteria and studied for expression of CD20, BCL2, BCL6, CD10, MUM-1, and HGAL by immunohistochemistry. Results were correlated with clinical features. HGAL and BCL6 expression and germinal center B-cell phenotype were associated with primary cutaneous follicular center lymphoma. The combination of HGAL and BCL6 positivity had the highest sensitivity (88%) and specificity (100%) for predicting subtype compared to either marker alone. Both HGAL and BCL6 were associated with the germinal center B-cell phenotype. The correlation of HGAL expression with the germinal center B-cell phenotype demonstrates the role of this marker in the classification of cutaneous large B-cell lymphomas. BCL6 expression was the only immunohistochemical marker associated with overall survival. Characterizing PCLBCLs with markers of B-cell maturation stage is a useful framework for studying, classifying, and clinically stratifying these lymphomas.

Low levels of Her2/neu expressed by Ewing's family tumor cell lines can redirect cytokine-induced killer cells.

PURPOSE: To identify novel treatments for pediatric solid tumors and/or for malignancies with low-level Her2/neu expression. EXPERIMENTAL DESIGN: Using fluorescence-activated cell sorting and immunohistochemistry, Her2/neu expression was determined on cell lines derived vfrom Ewing's family tumors (EFT) and neuroblastoma. Sensitivity to trastuzumab treatment was investigated using an in vitro proliferation assay. Cytotoxicity against EFT cell lines was done with either freshly isolated or ex vivo activated and expanded T cells (cytokine-induced killer cells, CIK cells), with or without addition of a CD3xHer2/neu bispecific antibody. The effects of either trastuzumab, CIK cells alone, or CD3xHer2/neu bispecific antibody redirected CIK cells was determined using a SCID/hu model of EFTs and serial, noninvasive bioluminescent imaging. RESULTS: EFT cell lines express 5- to 10-fold lower levels of her2/neu than either breast (BT-474) or ovarian (SK-OV-3) cell lines. Treatment of EFT cell lines with trastuzumab did not induce growth inhibition either in vitro or in vivo. In contrast, Her2/neu could be used to redirect CIK cell to mediate cytotoxicity against EFTs both in vitro and in vivo (using two different treatment schemas). CONCLUSIONS: CD3xHer2/neu bispecific antibody and CIK cells may be a suitable approach to treat malignancies with low-level Her2/neu expression not responsive to trastuzumab.

Rapamycin inhibits the interleukin 10 signal transduction pathway and the growth of Epstein Barr virus B-cell lymphomas.

EBV-infected B-cell lymphomas are a potentially life-threatening complication in bone marrow and solid organ transplant recipients. Immunosuppressive drugs required to prevent allograft rejection also impair anti-EBV T-cell immunity, thereby increasing the risk of EBV-associated disease. Here we demonstrate that the immunosuppressant rapamycin (RAPA) has a strong antiproliferative effect in vitro on B-cell lines derived from organ transplant recipients with EBV-associated posttransplant lymphoproliferative disorder (PTLD). Furthermore, RAPA significantly inhibits or delays the growth of solid tumors established from EBV-infected B-cell lines in a xenogeneic mouse model of PTLD. RAPA acts via cell cycle arrest, induction of apoptosis, and, most importantly, inhibition of interleukin 10 secretion, a necessary autocrine growth factor. The reduced interleukin 10 production is accompanied by corresponding decreases in the constitutive activation of the growth-promoting transcription factors signal transducer and activator of transcription 1 and 3. Thus, RAPA can limit B-cell lymphoma growth while simultaneously providing immunosuppression to prevent graft rejection in patients who are otherwise at risk for EBV-associated PTLD. Moreover, these findings may have application to other EBV-associated malignancies.