Transcriptional profiling of the nuclear factor-kappaB pathway identifies a subgroup of primary lymphoma of the central nervous system with low BCL10 expression

Identify novel inflammation-related prognostic signature in pancreatic cancer patients

Pancreatic cancer (PC) is a malignant tumor of the digestive system with a poor prognosis. PC patients with pancreatitis have a worse prognosis. But nobody reported the relationship between inflammation and prognosis in PC. Based on this, we are going to explore inflammation-related prognostic signature to predict patients' survival and potential therapeutic target. We screened gene expression profile and corresponding clinical information of patients from The Cancer Genome Atlas (TCGA) database. Gene set enrichment analysis (GSEA) was performed to identify differentially expressed genes (DEGs) between tumor and normal tissues with P value < .05. Univariate and multivariate Cox regression analysis was applied to identify possible prognostic inflammation genes and establish an inflammation-related risk score system, which was validated by Kaplan-Meier and Receiver operating characteristic (ROC) curves. Finally, we used the TISIDB database to predict targeted drugs for up-regulated gene hepatocyte growth factor receptor (MET) and used AUTODOCK software for molecular docking. We built a prognostic model consisted of 3 inflammation-related genes (tumor necrosis factor receptor associated factor 1/TFAR1, tyrosine kinase 2/TYK2, MET). According to the median value of those genes' risk score, PC patients were ranked into high- (88) and low-risk (89) groups. Then, the results of the Kaplan-Meier curves and the area under the curve (AUC) of the ROC curves showed this model had a good predictive power (P < .001, AUC = 0.806). The result of human protein atlas (HPA) database showed the expression of TRAF1 and TYK2 were low in pancreatic cancer, the expression of MET was high. TISIDB database founded brigatinib could target to MET. And AUTODOCK showed brigatinib had a nice docking with MET. Taken together, our study suggested that inflammation-associated prognostic signature might be used as novel biomarkers for predicting prognosis in PC patients and potential therapeutic target of the disease.

Lymphomas of Central Nervous System

Central nervous system (CNS) lymphoma consists of primary central nervous system lymphoma (PCNSL) and secondary CNS involvement by systemic lymphoma. This chapter focuses on the former. PCNSL is a relative rare disease, accounting for approximately 2.4-4.9% of all primary CNS tumors. It is an extra-nodal variant of non-Hodgkin's lymphoma (NHL), confined to the brain, leptomeninges, spinal cord, and eyes, with no systemic involvement. Recently, elderly patients (≥ 60 years) are increasing. Histologically, B cell blasts, which originate from late germinal center exit B cell, are growing and homing in CNS. Immunohistochemically, these cells are positive for PAX5, CD19, CD20, CD22, and CD79a. PCNSL shows relatively characteristic appearances on CT, MR imaging, and PET. Treatment first line of PCNSL is HD-MTX-based chemotherapy with or without rituximab and irradiation. Severe side-effect of this treatment is delayed onset neurotoxicity, which cause of cognitive impairment. Therefore, combined chemotherapy alone or chemotherapy with reduced-dose irradiation is more recommended for elderly patients. There is no established standard care for relapse of the PCNSLs. Temsirolimus, lenalidomide, temozolomide, and Bruton's tyrosine kinase (BTK) inhibitor ibrutinib are candidates for refractory patients. The prognosis of PCNSL has significantly improved over the last decades (median OS: 26 months, 5-year survival: 31%). Younger than 60 age and WHO performance status less than < or = 1 are associated with a significantly better overall survival.

Impact of a Faulty Germinal Center Reaction on the Pathogenesis of Primary Diffuse Large B Cell Lymphoma of the Central Nervous System

Simple Summary

The pathogenetic mechanisms and peculiar tropism of primary CNS lymphoma (PCNSL) of the central nervous system (CNS) have been the subject of debate for decades. Hypothesis-driven targeted molecular studies have revealed that PCNSLs derived from self-/polyreactive B cells that have escaped developmental control mechanisms. The early acquisition of activating mutations targeting the B cell receptor pathway provides a survival advantage. The failure of the germinal center (GC) reaction and its checkpoints increases tumor B cell affinity for the CNS. During this faulty GC reaction, PCNSL tumor cells acquire further oncogenic alterations converging on the Toll-like receptor, B cell receptor, and NF-κB pathway. These activated pathways sustain proliferation. Concomitantly, cells become unable to complete terminal B cell differentiation, becoming trapped within the vicious cycle of the GC reaction as low-affinity IgM+ B cells related to memory cells.

Abstract

Primary lymphoma of the central nervous system (PCNSL, CNS) is a specific diffuse large B cell lymphoma (DLBCL) entity confined to the CNS. Key to its pathogenesis is a failure of B cell differentiation and a lack of appropriate control at differentiation stages before entrance and within the germinal center (GC). Self-/polyreactive B cells rescued from apoptosis by MYD88 and/or CD79B mutations accumulate a high load of somatic mutations in their rearranged immunoglobulin (IG) genes, with ongoing somatic hypermutation (SHM). Furthermore, the targeting of oncogenes by aberrant SHM (e.g., PIM1, PAX5, RHOH, MYC, BTG2, KLHL14, SUSD2), translocations of the IG and BCL6 genes, and genomic instability (e.g., gains of 18q21; losses of 9p21, 8q12, 6q21) occur in these cells in the course of their malignant transformation. Activated Toll-like receptor, B cell receptor (BCR), and NF-κB signaling pathways foster lymphoma cell proliferation. Hence, tumor cells are arrested in a late B cell differentiation stage, corresponding to late GC exit B cells, which are genetically related to IgM+ memory cells. Paradoxically, the GC reaction increases self-/polyreactivity, yielding increased tumor BCR reactivity for multiple CNS proteins, which likely contributes to CNS tropism of the lymphoma. The loss of MHC class I antigen expression supports tumor cell immune escape. Thus, specific and unique interactions of the tumor cells with resident CNS cells determine the hallmarks of PCNSL.

PD-L1 gene alterations identify a subset of diffuse large B-cell lymphoma harboring a T-cell-inflamed phenotype

Programmed death-ligand 1 (PD-L1) expression on malignant cells is a dominant immune escape mechanism across a variety of human cancers. A unique genetic mechanism underlying PD-L1 upregulation has been uncovered in classical Hodgkin lymphoma (cHL), in which copy gains of the chromosomal region (9p24.1) containing the programmed death-1 (PD-1) ligands PD-L1 and PD-L2 are recurrently observed. While chromosome 9p24.1 copy-number alterations are ubiquitous in cHL, they also occur in diffuse large B-cell lymphoma (DLBCL), albeit with a lower incidence. Here, fluorescence in situ hybridization was used to identify DLBCLs harboring PD-L1 gene alterations, thereby enabling a characterization of the immunogenomic landscape of these lymphomas. Among 105 DLBCL cases analyzed, PD-L1 alterations were identified in 27%. PD-L1 alterations were highly enriched among non-germinal center DLBCLs and exhibited robust PD-L1 protein expression. These lymphomas were heavily infiltrated by clonally restricted T cells and frequently downregulated human leukocyte antigen expression. RNA sequencing of PD-L1-altered DLBCLs revealed upregulation of genes involved in negative T-cell regulation and NF-κB pathway activation, while whole-exome sequencing identified frequent mutations in genes involved in antigen presentation and T-cell costimulation. Many of these findings were validated in a large external data set. Interestingly, DLBCL patients with PD-L1 alterations had inferior progression-free survival following front-line chemoimmunotherapy; however, in the relapsed/refractory setting, PD-L1 alterations were associated with response to anti-PD-1 therapy. Collectively, our results indicate that PD-L1 alterations identify a unique biological subset of DLBCL in which an endogenous antilymphoma immune response has been activated, and that is associated with responsiveness to PD-1 blockade therapy.

Novel agents for primary central nervous system lymphoma: evidence and perspectives

Primary central nervous system lymphoma (PCNSL) is a rare aggressive extranodal non- Hodgkin lymphoma. Although high remission rates can be achieved with high-dose methotrexate-based immunochemotherapy, risk of relapse and associated death is still substantial in at least a third of patients. Novel agents for treating lymphoid malignancies have substantially enriched treatment options for PCNSL. We herein systematically review the existing clinical evidence of novel agents in treatment of PCNSL, summarize ongoing studies, and discuss perspectives. The body of evidence for novel agents is still limited to noncomparative studies, but the most promising approaches include Bruton kinase inhibition with ibrutinib and immunomodulatory treatment (eg, with lenalidomide). Targeting the mammalian target of rapamycin pathway does not seem to have a meaningful clinical benefit, and evidence of checkpoint inhibition with nivolumab is limited to anecdotal evidence. Future studies should embrace the concept of induction and maintenance therapy as well as the combination of drugs with different mechanisms of action. Selection of patients based on molecular profiling and relapse patterns should be another aspect informing future comparative trials, which are urgently needed to improve prognosis for patients with PCNSL.

Target amplicon exome-sequencing identifies promising diagnosis and prognostic markers involved in RTK-RAS and PI3K-AKT signaling as central oncopathways in primary central nervous system lymphoma

Exome-sequencing for somatic mutation detection and copy number variation analysis are effective and valid methods for evaluating human cancers in current molecular medicine. We conducted target amplicon exome-sequencing analyses using PCR target enrichment and next-generation sequencing on Ion Proton semiconductor sequencers. Twenty-seven primary central nervous system lymphoma (PCNSL) specimens and their corresponding noncancerous tissues were used for multiplex PCR amplification to obtain targeted coverages of the entire coding regions of 409 cancer-related genes. The average of the total numbers of somatic mutations including single-nucleotide variations and insertion/deletion mutations in each specimen was 13.3. Of these, the average of the ratios of nonsynonymous substitutions in each specimen was 74.8%. The most frequent mutations in 27 specimens were in PIM1, MYD88, CD79B, DST, IRF4, ERBB3, MYH11, DCC, and KMT2D. Furthermore, somatic mutations of MYH11 were related to poor prognoses in PCNSL patients. Copy number variations were also duplicated and/or deleted from deep-sequencing in segmental genomic islands. In addition to these prognostic marker candidates, analysis of RTK-RAS-MAPK signaling and the PTEN-PI3K-AKT proapoptotic pathway showed that somatic activations and aberrations, respectively, may be involved in a promising central oncopathway harboring mTOR, c-Myc, FOXO1, and p53. This study provides a foundation for molecular targeted therapies based on genome diagnostics and prognosis in PCNSL.

Challenges and opportunities in primary CNS lymphoma: A systematic review

BACKGROUND

Historically, high-dose methotrexate (HD-MTX) plus consolidation chemotherapy and/or whole brain radiotherapy (WBRT) has been the gold standard on Primary Central Nervous System Lymphoma (PCNSL) management. We sought to examine and summarize the data, on clinical trial (CT) setting, investigating multi-modality treatment to PCNSL.

METHODS

We performed a systematic review of electronic databases (Medline, EMBASE, Cochrane Database and clinicaltrials.gov) and a manual search to identify original PCNSL phase 2 and phase 3 CT from the last 10years. After a 4stage Prisma based selection process, 32 published (3 Randomized CT and 29 phases 2 CT) studies ultimately were selected for review. Four ongoing clinical trials found on clinicaltrial.gov were reviewed. Two investigators reviewed titles, abstracts, and articles independently. Two investigators abstracted data sequentially and evaluated each study independently.

FINDINGS

Treatment of PCNSL requires a multidisciplinary approach. HD-MTX represents the most accepted standard of care induction therapy for newly diagnosed PCNSL. When HD-MTX is given with WBRT for consolidation delayed neurotoxicity can be an important complication, particularly in elderly patients. Studies have suggested that WBRT may be deferred until relapse without compromising survival and deferring WBRT may be the best approach in elderly patients. Results from dose-reduced WBRT and consolidative HD-Ara-C are encouraging. High-dose chemotherapy in combination with autologous stem cell transplantation (HDC-ASCT) as chemotherapy alone has emerged as an important consolidative treatment for selected population. The optimal salvage therapy is still to be defined.

CONCLUSION

WBRT for consolidation is a well-studied modality; however emerging options to selected population such as HDC-ASCT, dose-reduced WBRT or chemotherapy alone are associated with similar survival outcome and less neurotoxicity in selected series. Ongoing and future clinical trials will better define the best approach on this rare disease.

Expression of Tim-1 in primary CNS lymphoma

Primary central nervous system lymphoma (PCNSL) is a distinct subtype of extranodal lymphoma with aggressive clinical course and poor outcome. As increased IL‐10/IL‐6 ratio is recognized in the cerebrospinal fluid (CSF) of PCNSL patients, we hypothesized that PCNSL might originate from a population of B cells with high IL‐10‐producing capacity, an equivalent of “regulatory B cells” in mice. We intended in this study to clarify whether Tim‐1, a molecule known as a marker for regulatory B cells in mice, is expressed in PCNSL. By immunohistochemical analysis, Tim‐1 was shown to be positive in as high as 54.2% of PCNSL (26 of 58 samples), while it was positive in 19.1% of systemic diffuse large B‐cell lymphoma (DLBCL) samples (17 of 89 samples; P < 0.001). Tim‐1 expression positively correlated with IL‐10 expression in PCNSL (Cramer's V = 0.55, P < 0.001), and forced expression of Tim‐1 in a PCNSL cell line resulted in increased IL‐10 secretion, suggesting that Tim‐1 is functionally linked with IL‐10 production in PCNSL. Moreover, soluble Tim‐1 was detectable in the CSF of PCNSL patients, and was suggested to parallel disease activity. In summary, PCNSL is characterized by frequent Tim‐1 expression, and its soluble form in CSF may become a useful biomarker for PCNSL.

Concomitant high expression of Toll-like receptor (TLR) and B-cell receptor (BCR) signalling molecules has clinical implications in mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive disease with frequent relapse. Targeted therapies against B-cell receptor (BCR) molecules have demonstrated improved outcomes in relapsed cases. However, clinical responses are slow and selective, with failure to attain complete remission in a significant subset of patients. Complex interaction of BCR signal transduction with toll-like receptor (TLR) and other pathways in MCL remains unknown, thus averting progress in development of targeted therapies. We have performed detailed digital quantification of BCR/TLR signalling molecules and their effector pathways in a cohort (n = 81) of MCL patients and correlated these data with overall survival. Hierarchical clustering model based on BCR/TLR genes revealed two distinct (BCR^high and BCR^low ) subsets of patients (n = 32; 40%) with significant differences in expression (>1.5-fold change; p < 0.05). Higher levels of BTK/SYK/BLNK/CARD11/PLCG signalosome and lower expression of MALT1/BCL10 genes suggested tonic pattern of BCR activation. Amplified expression of TLR6/TLR7/TLR9 was noted in concert with hyper-responsiveness of BCR machinery. MYD88, a key TLR adaptor molecule, was not upregulated in any of these clusters, which may suggest a 'cross-talk' between BCR and TLR pathways. In sync with BCR/TLR signalling, we recorded significantly enhanced expression of genes associated with NF-kB pathway in BCR^high subset of MCL patients. On univariate analysis, the BCR^high patients showed a trend towards inferior clinical response to a standardized treatment protocol, compared with the BCR^low group (log rank, p = 0.043). In conclusion, we have identified hyperactive BCR/TLR signalling pathways and their effector downstream targets in a subset of MCL patients and associated it with poor clinical outcomes. Our study provides quantitative evidence at RNA expression level of possible concomitant collaboration between TLR and BCR signalling molecules in MCL. These data will provide further insights for future functional studies and, hence, development of targeted therapies for MCL patients. Copyright © 2015 John Wiley & Sons, Ltd.

Primary Central Nervous System (CNS) Lymphoma B Cell Receptors Recognize CNS Proteins

Primary lymphoma of the CNS (PCNSL) is a diffuse large B cell lymphoma confined to the CNS. To elucidate its peculiar organ tropism, we generated recombinant Abs (recAbs) identical to the BCR of 23 PCNSLs from immunocompetent patients. Although none of the recAbs showed self-reactivity upon testing with common autoantigens, they recognized 1547 proteins present on a large-scale protein microarray, indicating polyreactivity. Interestingly, proteins (GRINL1A, centaurin-α, BAIAP2) recognized by the recAbs are physiologically expressed by CNS neurons. Furthermore, 87% (20/23) of the recAbs, including all Abs derived from IGHV4-34 using PCNSL, recognized galectin-3, which was upregulated on microglia/macrophages, astrocytes, and cerebral endothelial cells upon CNS invasion by PCNSL. Thus, PCNSL Ig may recognize CNS proteins as self-Ags. Their interaction may contribute to BCR signaling with sustained NF-κB activation and, ultimately, may foster tumor cell proliferation and survival. These data may also explain, at least in part, the affinity of PCNSL cells for the CNS.

Differential expression of Toll-like receptor (TLR) and B cell receptor (BCR) signaling molecules in primary diffuse large B-cell lymphoma of the central nervous system

Primary diffuse large B-cell lymphoma of the central nervous system (CNS DLBCL) is a distinct and aggressive lymphoma that is confined to CNS. Since, central nervous system is barrier-protected and immunologically silent; role of TLR/BCR signaling in pathogenesis and biology of CNS DLBCL is intriguing. Genomic mutations in key regulators of TLR/BCR signaling pathway (MYD88/CD79B/CARD11) have recently been reported in this disease. These observations raised possible implications in novel targeted therapies; however, expression pattern of molecules related to TLR/BCR pathways in this lymphoma remains unknown. We have analyzed the expression of 19 genes encoding TLR/BCR pathways and targets in CNS DLBCLs (n = 20) by Nanostring nCounter™ analysis and compared it with expression patterns in purified reactive B-lymphocytes and systemic diffuse large B cell lymphoma (DLBCL) (n = 20). Relative expression of TLR4, TLR5, TLR9, CD79B and BLNK was higher in CNS DLBCLs than in control B-lymphocytes; where as TLR7, MALT1, BCL10, CD79A and LYN was lower in CNS DLBCLs (P < 0.0001). When compared with systemic DLBCL samples, higher expression of TLR9, CD79B, CARD11, LYN and BLNK was noted in CNS DLBCL (>1.5 fold change; P < 0.01). The B cell receptor molecules like BLNK and CD79B were also associated with higher expression of MYD88 dependent TLRs (TLR4/5/9). In conclusion, we have shown over expression of TLR/BCR related genes or their targets, where genomic mutations have commonly been identified in CNS DLBCL. We have also demonstrated that TLR over expression closely relate with up regulation of genes associated with BCR pathway like CD79B/BLNK and CARD11, which play an important role in NF-kB pathway activation. Our results provide an important insight into the possibility of TLR and/or B-cell receptor signaling molecules as possible therapeutic targets in CNS DLBCL.

The mutational pattern of primary lymphoma of the central nervous system determined by whole-exome sequencing

To decipher the mutational pattern of primary CNS lymphoma (PCNSL), we performed whole-exome sequencing to a median coverage of 103 × followed by mutation verification in 9 PCNSL and validation using Sanger sequencing in 22 PCNSL. We identified a median of 202 (range: 139-251) potentially somatic single nucleotide variants (SNV) and 14 small indels (range: 7-22) with potentially protein-changing features per PCNSL. Mutations affected the B-cell receptor, toll-like receptor, and NF-κB and genes involved in chromatin structure and modifications, cell-cycle regulation, and immune recognition. A median of 22.2% (range: 20.0-24.7%) of somatic SNVs in 9 PCNSL overlaps with the RGYW motif targeted by somatic hypermutation (SHM); a median of 7.9% (range: 6.2-12.6%) affects its hotspot position suggesting a major impact of SHM on PCNSL pathogenesis. In addition to the well-known targets of aberrant SHM (aSHM) (PIM1), our data suggest new targets of aSHM (KLHL14, OSBPL10, and SUSD2). Among the four most frequently mutated genes was ODZ4 showing protein-changing mutations in 4/9 PCNSL. Together with mutations affecting CSMD2, CSMD3, and PTPRD, these findings may suggest that alterations in genes having a role in CNS development may facilitate diffuse large B-cell lymphoma manifestation in the CNS. This may point to intriguing mechanisms of CNS tropism in PCNSL.

Systems biology of primary CNS lymphoma: from genetic aberrations to modeling in mice

Primary lymphoma of the central nervous system (CNS, PCNSL) is a specific diffuse large B cell lymphoma entity arising in and confined to the CNS. Despite extensive research since many decades, the pathogenetic mechanisms underlying the remarkable tropism of this peculiar malignant hematopoietic tumor remain still to be elucidated. In the present review, we summarize the present knowledge on the genotypic and phenotypic characteristics of the tumor cells of PCNSL, give an overview over deregulated molecular pathways in PCNSL and present recent progress in the field of preclinical modeling of PCNSL in mice. With regard to the phenotype, PCNSL cells resemble late germinal center exit IgM+IgD+ B cells with blocked terminal B cell differentiation. They show continued BCL6 activity in line with ongoing activity of the germinal center program. This together with the pathways deregulated by genetic alterations may foster B cell activation and brisk proliferation, which correlated with the simultaneous MYC and BCL2 overexpression characteristic for PCNSL. On the genetic level, PCNSL are characterized by ongoing aberrant somatic hypermutation that, besides the IG locus, targets the PAX5, TTF, MYC, and PIM1 genes. Moreover, PCNSL cells show impaired IG class switch due to sμ region deletions, and PRDM1 mutations. Several important pathways, i.e., the B cell receptor (BCR), the toll-like receptor, and the nuclear factor-κB pathway, are activated frequently due to genetic changes affecting genes like CD79B, SHIP, CBL, BLNK, CARD11, MALT1, BCL2, and MYD88. These changes likely foster tumor cell survival. Nevertheless, many of these features are also present in subsets of systemic DLBLC and might not be the only reasons for the peculiar tropism of PCNSL. Here, preclinical animal models that closely mimic the clinical course and neuropathology of human PCNSL may provide further insight and we discuss recent advances in this field. Such models enable us to understand the pathogenetic interaction between the malignant B cells, resident cell populations of the CNS, and the associated inflammatory infiltrate. Indeed, the immunophenotype of the CNS as well as tumor cell characteristics and intracerebral interactions may create a micromilieu particularly conducive to PCNSL that may foster aggressiveness of tumor cells and accelerate the fatal course of disease. Suitable animal models may also serve as a well-defined preclinical system and may provide a useful tool for developing new specific therapeutic strategies.

Beyond high-dose methotrexate and brain radiotherapy: novel targets and agents for primary CNS lymphoma

BACKGROUND

While there has been significant progress in outcomes for patients diagnosed with primary central nervous system (CNS) lymphoma (PCNSL), survival rates will likely plateau with the current armamentarium of agents used to treat these patients. Moreover, given that PCNSL increasingly impacts an older population, a significant proportion of patients are not eligible for intensive therapies such as high-dose chemotherapy or whole-brain radiation. There is a need for the development of novel agents, which target key survival pathways in order to continue to make progress in this disease.

PATIENTS AND METHODS

We reviewed the key molecular pathways and genomic aberrations in PCNSL in order to identify candidate targets. We focused on molecules and pathways that have been identified and confirmed by more than one investigator or methodology.

RESULTS

While PCNSL tumors usually express a BCL6+, MUM1+ 'activated, germinal center' immunophenotype, they exhibit multiple shared genetic properties with ABC-type diffuse large B-cell lymphomas. Candidate targets and pathways include NFkB, the B-cell receptor, the JAK/STAT pathway, IRF4, BCL-6 as well as PIM kinases. Elements of the tumor microenvironment that may be exploited therapeutically include chemokine pathways, as well as macrophage and T-cell responses.

CONCLUSIONS

There is a significant need for developing novel therapies in PCNSL, given that an increasing proportion of patients are not eligible for high-dose chemotherapy and brain radiation is associated with detrimental cognitive side-effects. We provide an overview of potential drug targets and novel agents that may be integrated with existing strategies in order to make further progress in this disease.

How I treat CNS lymphomas

The pathogenesis of primary and secondary central nervous system (CNS) lymphoma poses a unique set of diagnostic, prognostic, and therapeutic challenges. During the past 10 years, there has been significant progress in the elucidation of the molecular properties of CNS lymphomas and their microenvironment, as well as evolution in the development of novel treatment strategies. Although a CNS lymphoma diagnosis was once assumed to be uniformly associated with a dismal prognosis, it is now reasonable to anticipate long-term survival, and possibly a cure, for a significant fraction of CNS lymphoma patients. The pathogenesis of CNS lymphomas affects multiple compartments within the neuroaxis, and proper treatment of the CNS lymphoma patient requires a multidisciplinary team with expertise not only in hematology/oncology but also in neurology, neuroradiology, neurosurgery, clinical neuropsychology, ophthalmology, pathology, and radiation oncology. Given the evolving principles of management and the evidence for improvements in survival, our goal is to provide an overview of current knowledge regarding the pathogenesis of CNS lymphomas and to highlight promising strategies that we believe to be most effective in establishing diagnosis, staging, and therapeutic management.

Mechanisms of intracerebral lymphoma growth delineated in a syngeneic mouse model of central nervous system lymphoma

Primary lymphoma of the central nervous system (PCNSL) is defined as lymphoma of the diffuse large B-cell type confined to the CNS. To understand the effects of the CNS microenvironment on the malignant B cells and their interactions with the cells of the target organ, we analyzed a syngeneic mouse model. Transplantation of BAL17 cells into the frontal white matter of syngeneic BALB/c mice induced lymphomas with major clinical and neuropathologic features that parallel those of human PCNSL, including an angiocentric growth pattern in the brain parenchyma and tropism for the inner and outer ventricular system. Seven cycles of repeated isolation of lymphoma cells from the CNS and their intracerebral reimplantation induced genotypic and phenotypic alterations in resulting BAL17VII cells; the affected genes regulate apoptosis and are of the JAK/STAT pathway. Because lymphoma growth of BAL17VII cells was significantly accelerated, that is, shortening the time to death of the mice, these data indicate that prolonged stay of the lymphoma cells in the CNS was associated with worse outcome. These findings suggest that the CNS microenvironment fosters aggressiveness of lymphoma cells, thereby accelerating the lethal course of PCNSL.

Expression of B-cell activating factor, a proliferating inducing ligand and its receptors in primary central nervous system lymphoma

B-cell activating factor belonging to the tumor necrosis factor family (BAFF) and a proliferating inducing ligand (APRIL) might play an important role in the pathogenesis of systemic B-cell malignancies. However, the BAFF/APRIL system has not been systematically evaluated in primary central nervous system lymphoma (PCNSL) to date. We assessed the expression of BAFF, APRIL and its receptors BAFF-R (BAFF receptor), BCMA (B-cell maturation antigen) and TACI (transmembrane activator and calcium modulator cyclophilin ligand interactor) in five PCNSL specimens by immunohistochemical staining. We found extensive expression of BAFF and weak to moderate expression of APRIL, BAFF-R, BCMA, and TACI in all specimens. CD20 positive cells showed expression of both ligands and receptors at the same time. Our results indicate that autocrine stimulation of the BAFF/APRIL system might be involved in the pathogenesis of PCNSL.

Pathogenesis and management of primary CNS lymphoma

Primary CNS lymphoma (PCNSL), a rare variant of extranodal non-Hodgkin's lymphoma, may cause various neurological symptoms and signs. The best therapeutic strategy is still a matter of debate. High-dose methotrexate (HD-MTX) is the most active compound and should be used as the backbone for any chemotherapy applied. Several other chemotherapeutic drugs have been assessed in combination with HD-MTX, but no standard has yet been defined. Whole-brain radiotherapy is active against PCNSL, but typically does not confer long-lasting remission and is associated with significant neurotoxicity in many patients. The recently published G-PCNSL-SG1 trial has shown that consolidating whole-brain radiotherapy after HD-MTX-based chemotherapy does not prolong overall survival and may therefore be deferred. Combined systemic and intraventricular polychemotherapy, or high-dose chemotherapy followed by stem cell transplantation may offer cures to younger patients. Improving treatment regimens without adding significant (neuro-)toxicity should be the focus of ongoing and future studies.

Modern concepts in the biology, diagnosis, differential diagnosis and treatment of primary central nervous system lymphoma

Recent studies addressing the molecular characteristics of PCNSL, which is defined as malignant B-cell lymphoma with morphological features of DLBCL, have significantly improved our understanding of the pathogenesis of this lymphoma entity, which is associated with an inferior prognosis as compared with DLBCL outside the CNS. This unfavorable prognosis stimulated intense efforts to improve therapy and induced recent series of clinical studies, which addressed the role of radiotherapy and various chemotherapeutic regimens. This review combines the discussion of diagnosis, differential diagnosis and recent progress in studies addressing the molecular pathogenesis as well as therapeutic options in PCNSL.

How I treat primary CNS lymphoma

Primary CNS lymphoma (PCNSL) is a rare malignancy with peculiar clinical and biologic features, aggressive course, and unsatisfactory outcome. It represents a challenge for multidisciplinary clinicians and scientists as therapeutic progress is inhibited by several issues. Molecular and biologic knowledge is incomplete, limiting the identification of new therapeutic targets, and the particular microenvironment of this malignancy, and sanctuary sites where tumor cells grow undisturbed, strongly affects treatment efficacy. Moreover, active treatments are known to be associated with disabling neurotoxicity, posing the dilemma of whether to intensify therapy to improve the cure rate or to de-escalate treatment to avoid sequels. The execution of prospective trials is also difficult because of the rarity of the tumor and the impaired general condition and poor performance status of patients. Thus, level of evidence is low, with consequent uncertainties in therapeutic decisions and lack of consensus on primary endpoints for future trials. Despite this unfavorable background, laboratory and clinical researchers are coordinating efforts to develop new ideas, resulting in the recent publication of studies on PCNSL's biology and molecular mechanisms and of the first international randomized trials. Herein, these important contributions are analyzed to provide recommendations for everyday practice and the rationale for future trials.

Primary CNS lymphoma

Primary CNS Lymphoma (PCNSL) accounts for 3% of all primary brain tumors with a median age at onset of about 62 years. In the vast majority of cases, PCNSL presents as unifocal or multifocal enhancing lesions on MRI, frequently adjacent to the ventricles. Stereotactic biopsy is the diagnostic procedure of choice revealing high-grade malignant non-Hodgkin's B-cell lymphoma in more than 90% of cases. Therapy is not evidence based. When eligible, patients should be included in clinical trials. In patients younger than 60 years cure is the aim. Polychemotherapy based on high-dose methotrexate (MTX) or alternatively high-dose chemotherapy with autologous stem cell rescue should be offered to patients eligible for this regimens. For patients over 60 years of age no curative regimen with acceptable toxicity has yet been established. An MTX-based chemotherapy, for example, in combination with temozolomide, is recommended. The role of radiotherapy as part of the initial treatment is not established; however, the combination of radiotherapy with MTX-based chemotherapy potentially leads to severe long-term neurotoxic sequelae. Therefore, radiotherapy as part of the initial therapy is not recommended by the author outside clinical trials. At relapse or in cases of refractory disease, patients will frequently benefit of salvage therapy, which depends on the initial treatment.

Mutations of CARD11 but not TNFAIP3 may activate the NF-kappaB pathway in primary CNS lymphoma

Primary CNS lymphoma (PCNSL), the intracerebral subgroup of diffuse large B cell lymphoma (DLBCL), shows evidence for aberrant activation of the nuclear factor (NF)-kappaB pathway. In order to identify potential activators of the NF-kappaB complex, we analyzed the CARD11 and TNFAIP3 genes for the presence of somatic mutations and TNFAIP3 for aberrant promoter methylation in PCNSL. We also compared PCNSL to spinal DLBCL, because CARD11 and TNFAIP3 mutations have been described in systemic DLBCL. CARD11 mutations, located in the coiled-coil region, which may activate NF-kappaB, were detected in 16% (5/32) of PCNSL, while TNFAIP3 mutations were detected in 3% (1/32) of PCNSL. In PCNSL, all CARD11 mutations were heterozygous, in-frame, induced amino acid exchanges, and presumably led to activation of this oncogene. Spinal DLBCL harbored mutations of CARD11 and TNFAIP3 in 10% (1/10) and 20% (2/10) of cases, respectively. In both PCNSL and spinal DLBCL, mutations in CARD11 and TNFAIP3 were mutually exclusive. TNFAIP3 was unmethylated in all PCNSLs (30/30) and spinal DLBCLs (10/10). We conclude that mutations of the oncogene CARD11 may contribute to NF-kappaB activation and thereby play a role in the pathogenesis of PCNSL, while, in contrast to systemic DLBCL, inactivation of TNFAIP3 either by mutation or methylation seems to be of minor significance.

Pathophysiology of retinal lymphoma

Retinal lymphoma, the most common form of intraocular lymphoma, is a high-grade malignancy, usually of B-cell type, and is associated with a poor prognosis because of frequent central nervous system (CNS) involvement. The neoplastic B-cells of retinal lymphoma have a characteristic morphology and immunophenotype, express certain chemokines and chemokine receptors, and produce interleukins (IL), e.g. IL-10. Together with the cytological features of these tumors, the immunophenotype, presence of immunoglobulin rearrangements, and biochemical profile aid the diagnosis of retinal lymphomas. Immunophenotyping and somatic mutation analysis suggest derivation of most retinal lymphomas from an early post-germinal centre B-cell. Chromosomal translocation data would suggest, however, that a subgroup of these neoplasms may arise from germinal centre B-cells, and these could be associated with a better prognosis. Further investigations, such as gene expression profiling, are required to identify oncogenic pathways potentially involved in retinal lymphoma development, and to identify new prognostic/therapeutic markers for this tumor.

Chromosomal imbalances and partial uniparental disomies in primary central nervous system lymphoma

To determine the pattern of genetic alterations in primary central nervous system lymphomas (PCNSL), 19 PCNSL were studied by high-density single-nucleotide polymorphism arrays. Recurrent losses involved 6p21.32, 6q21, 8q12-12.2, 9p21.3, 3p14.2, 4q35.2, 10q23.21 and 12p13.2, whereas gains involved 18q21-23, 19q13.31, 19q13.43 and the entire chromosomes X and 12. Partial uniparental disomies (pUPDs) were identified in 6p and 9p21.3. These genomic alterations affected the HLA locus, the CDKN2A/p16, CDKN2B/p15 and MTAP, as well as the PRDM1, FAS, MALT1, and BCL2 genes. Increased methylation values of the CDKN2A/p16 promoter region were detected in 75% (6/8) PCNSL. Gene expression profiling showed 4/21 (20%) minimal common regions of imbalances to be associated with a differential mRNA expression affecting the FAS, STAT6, CD27, ARHGEF6 and SEPT6 genes. Collectively, this study unraveled novel genomic imbalances and pUPD with a high resolution in PCNSL and identified target genes of potential relevance in the pathogenesis of this lymphoma entity.

The 2008 WHO classification of lymphomas: implications for clinical practice and translational research

The 4(th) edition of the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues published in 2008 builds upon the success of the 2001 3(rd) edition; new entities are defined, and solutions for problematic categories are sought. Recent studies have drawn attention to the biological overlap between classical Hodgkin lymphoma (CHL) and diffuse large B-cell lymphomas (DLBCL). Similarly, there is a greater appreciation of the borderlands between Burkitt lymphoma and DLBCL. Strategies for the management of these borderline lesions are proposed. Additionally, age-specific and site-specific factors play an important role in the definition of several new entities, which also have biological underpinnings. Among the peripheral T-cell lymphomas (PTCL), more precise definitions were introduced for several entities, including anaplastic large cell lymphoma, angioimmunoblastic T-cell lymphoma, enteropathy-associated T-cell lymphoma, and subcutaneous panniculitis-like T-cell lymphoma. Several new variants of primary cutaneous T-cell lymphomas are proposed. Finally, the subclassification and categorization of the most common lymphoma subtypes, follicular lymphoma (FL) and DLBCL, were altered to enhance diagnostic accuracy and aid in clinical management. The 2008 WHO classification also draws attention to early events in lymphomagenesis. These lesions help delineate the earliest steps in neoplastic transformation and generally mandate a conservative therapeutic approach. The 2001 classification was rapidly adopted for clinical trials and successfully served as a common language for scientists comparing genetic and functional data. The modifications made in the 2008 classification are the result of this successful partnership among pathologists, clinicians, and biologists, but are only a stepping stone to the future.

The 2008 WHO classification of lymphomas: implications for clinical practice and translational research

The 4th edition of the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues published in 2008 builds upon the success of the 2001 3rd edition; new entities are defined, and solutions for problematic categories are sought. Recent studies have drawn attention to the biological overlap between classical Hodgkin lymphoma (CHL) and diffuse large B-cell lymphomas (DLBCL). Similarly, there is a greater appreciation of the borderlands between Burkitt lymphoma and DLBCL. Strategies for the management of these borderline lesions are proposed. Additionally, age-specific and site-specific factors play an important role in the definition of several new entities, which also have biological underpinnings. Among the peripheral T-cell lymphomas (PTCL), more precise definitions were introduced for several entities, including anaplastic large cell lymphoma, angioimmunoblastic T-cell lymphoma, enteropathy-associated T-cell lymphoma, and subcutaneous panniculitis-like T-cell lymphoma. Several new variants of primary cutaneous T-cell lymphomas are proposed. Finally, the subclassification and categorization of the most common lymphoma subtypes, follicular lymphoma (FL) and DLBCL, were altered to enhance diagnostic accuracy and aid in clinical management. The 2008 WHO classification also draws attention to early events in lymphomagenesis. These lesions help delineate the earliest steps in neoplastic transformation and generally mandate a conservative therapeutic approach. The 2001 classification was rapidly adopted for clinical trials and successfully served as a common language for scientists comparing genetic and functional data. The modifications made in the 2008 classification are the result of this successful partnership among pathologists, clinicians, and biologists, but are only a stepping stone to the future.

Gene expression profiling suggests primary central nervous system lymphomas to be derived from a late germinal center B cell

To characterize the molecular origin of primary lymphomas of the central nervous system (PCNSL), 21 PCNSLs of immunocompetent patients were investigated by microarray-based gene expression profiling. Comparison of the transcriptional profile of PCNSL with various normal and neoplastic B-cell subsets demonstrated PCNSL (i) to display gene expression patterns most closely related to late germinal center B cells, (ii) to display a gene expression profile similar to systemic diffuse large B-cell lymphomas (DLBCLs) and (iii) to be in part assigned to the activated B-cell-like (ABC) or the germinal center B-cell-like (GCB) subtype of DLBCL.

Expression pattern and cellular sources of chemokines in primary central nervous system lymphoma

The expression pattern of a subset of chemokines and their corresponding receptors was investigated in primary central nervous system lymphomas (PCNSL). The tumor cells consistently expressed CXCR4, CXCL12, CXCR5, and CXCL13, both at mRNA and protein levels. Cerebral endothelial cells were positive for CXCL12 and CXCL13, while reactive astrocytes and microglial cells expressed CXCL12, CCR5, and CCR6. Inflammatory T cells in PCNSL were characterized by CCR5 and CCR6 positivity. Taken together, our data indicate a cell type-specific repertoire of chemokine and chemokine receptor expression in PCNSL suggesting that chemokine-mediated interactions facilitate crossing of the blood-brain barrier as well as intracerebral dissemination of PCNSL cells. In addition, chemokines expressed by tumor cells may contribute to induction of reactive glial changes and influence the composition of inflammatory infiltrates in PCNSL. Therefore, cell type specific expression of distinct chemokine profiles likely plays a role in the pathogenesis of PCNSL and may contribute to their characteristic histological appearance.