Gene expression and angiotropism in primary CNS lymphoma

Liquid biopsy for improving diagnosis and monitoring of CNS lymphomas: A RANO review

BACKGROUND

The utility of liquid biopsies is well documented in several extracranial and intracranial (brain/leptomeningeal metastases, gliomas) tumors.

METHODS

The RANO (Response Assessment in Neuro-Oncology) group has set up a multidisciplinary Task Force to critically review the role of blood and cerebrospinal fluid (CSF)-liquid biopsy in CNS lymphomas, with a main focus on primary central nervous system lymphomas (PCNSL).

RESULTS

Several clinical applications are suggested: diagnosis of PCNSL in critical settings (elderly or frail patients, deep locations, and steroid responsiveness), definition of minimal residual disease, early indication of tumor response or relapse following treatments, and prediction of outcome.

CONCLUSIONS

Thus far, no clinically validated circulating biomarkers for managing both primary and secondary CNS lymphomas exist. There is need of standardization of biofluid collection, choice of analytes, and type of technique to perform the molecular analysis. The various assays should be evaluated through well-organized central testing within clinical trials.

New hopes in relapsed refractory primary central nervous system lymphoma

PURPOSE OF REVIEW

Patients with relapsed/refractory primary central nervous system lymphoma (rrPCNSL) have poor prognosis, with a median survival after relapse of 6.8 months. In this review, we discuss the evolving landscape and the possible future directions related to this important unmet clinical need.

RECENT FINDINGS

The modern two-phase approach for newly diagnosed PCNSL based on an induction using high-dose methotrexate (HD-MTX) combinations and a subsequent consolidation, has significantly improved the outcome in this setting. However, this strategy is able to cure more or less 50% of patients. rrPCNSL patients have a very poor prognosis with a reported 5-year overall survival of 18%. Late relapses (after third year) and use of high-dose chemotherapy and autologous stem cell transplantation (HDT-ASCT) represent important factors associated with a better outcome in this setting. On the basis of the growing acquisition of knowledge on the molecular characteristics of PCNSL, the use of non-chemotherapeutic drugs such as bruton tyrosine kinase inhibitors (BTK-is), immunomodulatory drugs (IMiDs) and immune checkpoint blockers (ICBs) is increasing in the last years along with the introduction of novel approaches (CAR-T cells and blood--brain barrier disruption). However, despite high responses in some cases, durations are often short, translating in outcome results still unsatisfactory.

SUMMARY

Treatment of rrPCNSL patients is challenging. As no standard of care exist in this setting, it is of paramount importance to acquire new knowledge related to this condition and start multidisciplinary collaboration in order to improve pts outcome.

Pretreatment diffusion-weighted imaging for prediction of relapsed and refractory primary central nervous system lymphoma

Objectives

A subset of primary central nervous system lymphoma (PCNSL) has been shown to undergo an early relapsed/refractory (R/R) period after first-line chemotherapy. This study investigated the pretreatment clinical and MRI features to predict R/R in PCNSL, emphasizing the apparent diffusion coefficient (ADC) values in diffusion-weighted imaging (DWI).

Methods

This retrospective study investigated the pretreatment MRI features for predicting R/R in PCNSL. Only patients who had undergone complete preoperative and postoperative MRI follow-up studies were included. From January 2006 to December 2021, 52 patients from two medical institutions with a diagnosis of PCNSL were included (median follow-up time, 26.3 months). Among these, 24 (46.2%) had developed R/R (median time to relapse, 13 months). Cox proportional hazard regression analyses were performed to determine hazard ratios for all parameters.

Results

Significant predictors of R/R in PCNSL were female sex, complete response (CR) to first-line chemotherapy, and ADC value/ratio (p < 0.05). Cut-off points of ADC values and ADC ratios for prediction of R/R were 0.68 × 10-3 mm2/s and 0.97, with AUCs of 0.78 and 0.77, respectively (p < 0.05). Multivariate Cox proportional hazards analysis showed that failure of CR to first-line chemotherapy and low ADC values (<0.68 × 10-3 mm2/s) were significant risk factors for R/R, with hazard ratios of 5.22 and 14.45, respectively (p < 0.05). Kaplan-Meier analysis showed that lower ADC values and ratios predicted significantly shorter progression-free survival (p < 0.05).

Conclusion

Pretreatment ADC values in DWI offer quantitative valuable information for the treatment planning in PCNSL.

Treatment Options for Epstein-Barr Virus-Related Disorders of the Central Nervous System

Epstein-Barr virus (EBV), a causative agent for several types of lymphomas and mucosal cancers, is a human lymphotropic herpesvirus with the capacity to establish lifelong latent infection. More than 90% of the human population worldwide is infected. The primary infection is usually asymptomatic in childhood, whereas infectious mononucleosis (IM) is common when the infection occurs in adolescence. Primary EBV infection, with or without IM, or reactivation of latent infection in immunocompromised individuals have been associated with a wide range of neurologic conditions, such as encephalitis, meningitis, acute disseminated encephalomyelitis, and cerebellitis. EBV is also involved in malignant lymphomas in the brain. An increasing number of reports on EBV-related disorders of the central nervous system (CNS) including the convincing association with multiple sclerosis (MS) have put in focus EBV-related conditions beyond its established link to malignancies. In this review, we present the clinical manifestations of EBV-related CNS-disorders, put them in the context of known EBV biology and focus on available treatment options and future therapeutic approaches.

Primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a diffuse large B cell lymphoma in which the brain, spinal cord, leptomeninges and/or eyes are exclusive sites of disease. Pathophysiology is incompletely understood, although a central role seems to comprise immunoglobulins binding to self-proteins expressed in the central nervous system (CNS) and alterations of genes involved in B cell receptor, Toll-like receptor and NF-κB signalling. Other factors such as T cells, macrophages or microglia, endothelial cells, chemokines, and interleukins, probably also have important roles. Clinical presentation varies depending on the involved regions of the CNS. Standard of care includes methotrexate-based polychemotherapy followed by age-tailored thiotepa-based conditioned autologous stem cell transplantation and, in patients unsuitable for such treatment, consolidation with whole-brain radiotherapy or single-drug maintenance. Personalized treatment, primary radiotherapy and only supportive care should be considered in unfit, frail patients. Despite available treatments, 15-25% of patients do not respond to chemotherapy and 25-50% relapse after initial response. Relapse rates are higher in older patients, although the prognosis of patients experiencing relapse is poor independent of age. Further research is needed to identify diagnostic biomarkers, treatments with higher efficacy and less neurotoxicity, strategies to improve the penetration of drugs into the CNS, and roles of other therapies such as immunotherapies and adoptive cell therapies.

Role of elastic fiber degradation in disease pathogenesis

Elastin is a crucial extracellular matrix protein that provides structural integrity to tissues. Crosslinked elastin and associated microfibrils, named elastic fiber, contribute to biomechanics by providing the elasticity required for proper function. During aging and disease, elastic fiber can be progressively degraded and since there is little elastin synthesis in adults, degraded elastic fiber is not regenerated. There is substantial evidence linking loss or damage of elastic fibers to the clinical manifestation and pathogenesis of a variety of diseases. Disruption of elastic fiber networks by hereditary mutations, aging, or pathogenic stimuli results in systemic ailments associated with the production of elastin degradation products, inflammatory responses, and abnormal physiology. Due to its longevity, unique mechanical properties, and widespread distribution in the body, elastic fiber plays a central role in homeostasis of various physiological systems. While pathogenesis related to elastic fiber degradation has been more thoroughly studied in elastic fiber rich tissues such as the vasculature and the lungs, even tissues containing relatively small quantities of elastic fibers such as the eyes or joints may be severely impacted by elastin degradation. Elastic fiber degradation is a common observation in certain hereditary, age, and specific risk factor exposure induced diseases representing a converging point of pathological clinical phenotypes which may also help explain the appearance of co-morbidities. In this review, we will first cover the role of elastic fiber degradation in the manifestation of hereditary diseases then individually explore the structural role and degradation effects of elastic fibers in various tissues and organ systems. Overall, stabilizing elastic fiber structures and repairing lost elastin may be effective strategies to reverse the effects of these diseases.

Signaling pathways in brain tumors and therapeutic interventions

Brain tumors, although rare, contribute to distinct mortality and morbidity at all ages. Although there are few therapeutic options for brain tumors, enhanced biological understanding and unexampled innovations in targeted therapies and immunotherapies have considerably improved patients' prognoses. Nonetheless, the reduced response rates and unavoidable drug resistance of currently available treatment approaches have become a barrier to further improvement in brain tumor (glioma, meningioma, CNS germ cell tumors, and CNS lymphoma) treatment. Previous literature data revealed that several different signaling pathways are dysregulated in brain tumor. Importantly, a better understanding of targeting signaling pathways that influences malignant behavior of brain tumor cells might open the way for the development of novel targeted therapies. Thus, there is an urgent need for a more comprehensive understanding of the pathogenesis of these brain tumors, which might result in greater progress in therapeutic approaches. This paper began with a brief description of the epidemiology, incidence, risk factors, as well as survival of brain tumors. Next, the major signaling pathways underlying these brain tumors' pathogenesis and current progress in therapies, including clinical trials, targeted therapies, immunotherapies, and system therapies, have been systemically reviewed and discussed. Finally, future perspective and challenges of development of novel therapeutic strategies in brain tumor were emphasized.

Primary CNS lymphoma: update on molecular pathogenesis and therapy

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive form of extra-nodal non-Hodgkin lymphoma that as a brain tumor poses a unique set of challenges in diagnosis and management. With the advent of next-generation sequencing, we review updates in the understanding of its molecular and genomic pathogenesis. We also highlight key issues in management, with a focus on emerging technologies and new biological therapies including monoclonal antibodies, IMiDs, BTK inhibitors, PD-1 inhibitors, and CAR-T therapy. Integration of these approaches will likely enhance induction and consolidation strategies to suppress NF-κB activation and the anti-tumor immune response, while minimizing the often noxious effects of genotoxic approaches.

Intratumor heterogeneity and T cell exhaustion in primary CNS lymphoma

Background

Primary central nervous system lymphoma (PCNSL) is a rare lymphoma of the central nervous system, usually of diffuse large B cell phenotype. Stereotactic biopsy followed by histopathology is the diagnostic standard. However, limited material is available from CNS biopsies, thus impeding an in-depth characterization of PCNSL.

Methods

We performed flow cytometry, single-cell RNA sequencing, and B cell receptor sequencing of PCNSL cells released from biopsy material, blood, and cerebrospinal fluid (CSF), and spatial transcriptomics of biopsy samples.

Results

PCNSL-released cells were predominantly activated CD19⁺CD20⁺CD38⁺CD27⁺ B cells. In single-cell RNA sequencing, PCNSL cells were transcriptionally heterogeneous, forming multiple malignant B cell clusters. Hyperexpanded B cell clones were shared between biopsy- and CSF- but not blood-derived cells. T cells in the tumor microenvironment upregulated immune checkpoint molecules, thereby recognizing immune evasion signals from PCNSL cells. Spatial transcriptomics revealed heterogeneous spatial organization of malignant B cell clusters, mirroring their transcriptional heterogeneity across patients, and pronounced expression of T cell exhaustion markers, co-localizing with a highly malignant B cell cluster.

Conclusions

Malignant B cells in PCNSL show transcriptional and spatial intratumor heterogeneity. T cell exhaustion is frequent in the PCNSL microenvironment, co-localizes with malignant cells, and highlights the potential of personalized treatments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-022-01110-1.

Advances in therapeutic strategies for primary CNS B-cell lymphomas

INTRODUCTION

Primary CNS lymphoma (PCNSL) has traditionally been treated with induction HD-MTX-based chemotherapy, followed by consolidation whole-brain radiotherapy. However, this approach is associated with significant neurocognitive complications, especially in older patients. Therefore, different consolidation protocols have been evaluated. High-dose chemotherapy followed by autologous stem cell transplantation (HD-ASCT) has the best long-term survival outcomes in younger patients.

AREAS COVERED

In this review of the literature, we focus on the overall therapeutic strategy and advances in the management of the aggressive primary CNS B-cell lymphomas.

EXPERT OPINION

In young and fit PCNSL patients, HD-ASCT is the preferred consolidation strategy to achieve long-term survivals. Older patients with good performance status should also be evaluated for MTX-based induction polychemotherapy followed by ASCT. However, management of PCNSL patients remains challenging, and new avenues with targeted therapies are under investigation. To date, ibrutinib, lenalidomide, and immune checkpoint inhibitors appearto be promising in PCNSL. However, as monotherapy, durable responses are less likely to be achieved. Unfortunately, when combined with chemoimmunotherapy, considerable toxicity and mortality have been reported. Clinical trials on these molecules are aiming to reduce toxicity and maintain responses. CAR-T-cell therapy has recently emerged as a further option. It has shown efficacy in patients with secondary CNS lymphoma, with few but encouraging results in primary CNSL.

Cell-of-origin classification using the Hans and Lymph2Cx algorithms in primary cutaneous large B-cell lymphomas

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT) and primary cutaneous follicle center lymphoma with a diffuse population of large cells (PCFCL-LC) are both primary cutaneous B-cell lymphomas with large-cell morphology (CLBCL) but with different clinical characteristics and behavior. In systemic diffuse large B-cell lymphoma, not otherwise specified (DLBCL-NOS), gene-expression profiling (GEP) revealed two molecular subgroups based on their cell-of-origin (COO) with prognostic significance: the germinal center B-cell-like (GCB) subtype and the activated B-cell-like (ABC) subtype. This study investigated whether COO classification is a useful tool for classification of CLBCL. For this retrospective study, 51 patients with PCDLBCL-LT and 15 patients with PCFCL-LC were analyzed for their COO according to the immunohistochemistry-based Hans algorithm and the NanoString GEP-based Lymph2Cx algorithm. In PCFCL-LC, all cases (100%) classified as GCB by both Hans and Lymph2Cx. In contrast, COO classification in PCDLBCL-LT was heterogeneous. Using Hans, 75% of the PCDLBCL-LT patients classified as non-GCB and 25% as GCB, while Lymph2Cx classified only 18% as ABC, 43% as unclassified/intermediate, and 39% as GCB. These COO subgroups did not differ in the expression of BCL2 and IgM, mutations in MYD88 and/or CD79B, loss of CDKN2A, or survival. In conclusion, PCFCL-LC uniformly classified as GCB, while PCDLBCL-LT classified along the COO spectrum of DLBCL-NOS using the Hans and Lymph2Cx algorithms. In contrast to DLBCL-NOS, the clinical relevance of COO classification in CLBCL using these algorithms has limitations and cannot be used as an alternative for the current multiparameter approach in differentiation of PCDLBCL-LT and PCFCL-LC.

Update on Novel Therapeutics for Primary CNS Lymphoma

Simple Summary

Primary central nervous system lymphoma is a rare and aggressive form of non-Hodgkin lymphoma. While it is highly responsive to first-line chemo and radiation treatments, rates of relapse are high, demonstrating the need for improved therapeutic strategies. Recent advancements in the understanding of the pathophysiology of this disease have led to the identification of new potential treatment targets and the development of novel agents. This review aims to discuss different targeted strategies and review some of the data supporting these approaches, and discusses recently completed and ongoing clinical trials using these novel agents.

Abstract

Primary central nervous system lymphoma (PCNSL) is a rare lymphoma isolated to the central nervous system or vitreoretinal space. Standard treatment consists of cytotoxic methotrexate-based chemotherapy, with or without radiation. Despite high rates of response, relapse is common, highlighting the need for novel therapeutic approaches. Recent advances in the understanding of PCNSL have elucidated mechanisms of pathogenesis and resistance including activation of the B-cell receptor and mammalian target of rapamycin pathways. Novel treatment strategies such as the Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib, phosphatidylinositol-3 kinase (PI3K) inhibitors, and immunomodulatory drugs are promising. Increasingly, evidence suggests immune evasion plays a role in PCNSL pathogenesis and several immunotherapeutic strategies including checkpoint inhibition and targeted chimeric antigen receptor T (CAR-T) cells are under investigation. This review provides a discussion on the challenges in development of targeted therapeutic strategies, an update on recent treatment advances, and offers a look toward ongoing clinical studies.

Analysis of Cellular Heterogeneity in Immune Microenvironment of Primary Central Nervous System Lymphoma by Single-Cell Sequencing

Background

Primary central nervous system lymphoma (PCNSL) is characterized by a lack of specificity and poor prognosis. Further understanding of the tumor heterogeneity and molecular phenotype of PCNSL is of great significance for improving the diagnosis and treatment of this disease.

Methods

To explore the distinct phenotypic states of PCNSL, transcriptome-wide single-cell RNA sequencing was performed on 34,851 PCNSL cells from patients. The cell types, heterogeneity, and gene subset enrichment of PCNSL were identified. A comparison of the PCNSL cells with 21,250 normal human fetal brain (nHFB) cells was further analyzed to reveal the differences between PCNSL and normal sample.

Results

Six cell populations were mainly identified in the PCNSL tissue, including four types of immune cells—B cell, T cell, macrophage and dendritic cell—and two types of stromal cells: oligodendrocyte and meningeal cell. There are significant cellular interactions between B cells and several other cells. Three subpopulations of B cells indicating diffident functions were identified, as well as a small number of plasma cells. Different subtypes of T cells and dendritic cells also showed significant heterogeneity. It should be noted that, compared with normal, the gene expression and immune function of macrophages in PCNSL were significantly downregulated, which may be another important feature of PCNSL in addition to B cell lesions and may be a potential target for PCNSL therapy.

Emerging Landscape of Immunotherapy for Primary Central Nervous System Lymphoma

Simple Summary

Primary central nervous system lymphoma (PCNSL) is characterized by its location in the central nervous system comprising the brain, the eye, the cerebrospinal fluid and the spinal cord and a poor prognosis with the current chemotherapies. Immunotherapies represent a new paradigm in the care of patients with B-cell lymphoma, but, till recently, immunotherapies studies excluded patients with PCNSL because of the lack of knowledge on the immune network in the brain. Recent studies shed a new light on the origin and characteristics of the CNS immune cells. We review the current experimental preclinical and clinical developments of immunotherapies in CNS lymphoma as well as the effects of targeted therapies on the brain microenvironment. We provide perspectives for improving the efficacy of immunotherapies in the specific setting of PCNSL for a better prognosis of this disease.

Abstract

Primary central nervous system lymphoma (PCNSL) is, mainly, a diffuse large B-cell lymphoma (DLBCL) with a non-germinal center B-cell (non-GCB) origin. It is associated with a poor prognosis and an unmet medical need. Immunotherapy has emerged as one of the most promising areas of research and is now part of the standard treatment for many solid and hematologic tumors. This new class of therapy generated great enthusiasm for the treatment of relapsed/refractory PCNSL. Here, we discuss the challenges of immunotherapy for PCNSL represented by the lymphoma cell itself and the specific immune brain microenvironment. We review the current clinical development from the anti-CD20 monoclonal antibody to CAR-T cells, as well as immune checkpoint inhibitors and targeted therapies with off-tumor effects on the brain microenvironment. Perspectives for improving the efficacy of immunotherapies and optimizing their therapeutic role in PCNSL are suggested.

Expression of STAT6 and Phosphorylated STAT6 in Primary Central Nervous System Lymphomas

The signal transducer and activator of transcription 6 (STAT6) is implicated in the pathogenesis of some lymphomas including primary central nervous system lymphomas (PCNSLs). The aim of this study was to investigate STAT6 expression and clinicopathologic features in 25 PCNSLs using immunohistochemistry with 2 different anti-STAT6 antibodies. One (YE361) recognizes the C-terminus domain of the STAT6 protein and the other (Y641) recognizes the phosphorylated form of the protein. The phosphorylated STAT6 form was not expressed in any of the cases studied whereas the YE361 STAT6 showed only cytoplasmic expression in 14 (56%) cases. This expression did not correlate with age, prognostic score, multiplicity, invasion of deep structures, response to treatment, disease recurrence, overall survival, or BCL6, BCL2, PD-L1, and CD8 expression. A STAT6 expression score showed a trend for correlating with clinical performance status. It also showed a positive correlation with MYC expression. Thus, the phosphorylated form of STAT6 was not found in the current series, while the YE361 STAT6 showed only cytoplasmic expression and was associated with expression of MYC.

STAT6: A review of a signaling pathway implicated in various diseases with a special emphasis in its usefulness in pathology

Signal Transducer and Activator of Transcription 6 (STAT6), belonging to a family of seven similar members is primarily stimulated by interleukin(IL)-4 and IL-13, and acts as a T helper type 2 (Th2)-inducing factor. Thus, it is implicated in the pathophysiology of various allergic conditions, such as asthma, atopic dermatitis, eosinophilic esophagitis and food allergies, but also in tumor microenvironment regulation. Furthermore, certain forms of lymphomas, notably the Hodgkin lymphoma group, the primary mediastinal and primary central nervous system lymphoma, as well as some follicular and T cell lymphomas are associated with dysregulation of the STAT6 pathway. STAT6 immunohistochemical expression also serves as a surrogate marker in the diagnosis of solitary fibrous tumor, despite not directly responsible for the tumorigenic effect. These pathophysiological implications of the STAT6 pathway, its diagnostic or prognostic role in pathology, as well its immunohistochemical detection with different antibodies will be discussed in this review.

Aggregative Perivascular Tumor Cell Growth Pattern of Primary Central Nervous System Lymphomas Is Associated with Hypoxia-Related Endoplasmic Reticulum Stress

Primary central nervous system lymphomas (PCNSLs) often present a unique histopathological feature of aggregative perivascular tumor cells (APVT). Our previous studies showed that patients of PCNSL with APVTs exhibited poor long-term outcomes and increased expression of the endoplasmic reticulum stress (ERS) factor X-box-binding protein (XBP1). However, very little is known about molecular mechanism of the APVT formation in PCNSLs. The aim of this study is to determine if hypoxia-induced ERS is related to the APVT formation in PCNSLs. In this study, cell culture was used to observe the interplay between diffuse large B cell lymphoma (DLBCL) tumor cells and human brain microvascular endothelial cells (HBMECs) in different oxygen conditions. The expression of XBP1, CXCR and CD44 was manipulated by molecular cloning and siRNA technology. Mouse in vivo experiments and clinical studies were conducted to confirm our hypothesis. Our results showed that activated B-cell type-DLBCL cells easily migrated and invaded, and expressed high levels of XBP1 and stromal molecules CXCR4 and CD44 during hypoxia-induced ERS and dithiothreitol unfolded protein response (UPR). The gene upregulation (using overexpression vector) and downregulation (siRNA gene knock-out) in cultured cells and in mouse models further confirmed a close relation of the expression of XBP1, CXCR4, and CD44 with APVT formation, which is coincided with our clinical observation that increased expression of XBP1, CXCR4, and CD44 in the APVT cells in PCNSLs were associated with poor clinical outcomes. The results suggest that hypoxia-induced ERS and UPR might be associated with APVTs formation in PCNSL and its poor clinical outcomes. The results will help us better understand the progression of PCNSL with APVTs feature in daily pathological work and could be valuable for future target treatment of PCNSLs.

Emerging insights into origin and pathobiology of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is an aggressive cancer typically confined to the brain, eyes, leptomeninges and spinal cord, without evidence of systemic involvement. PCNSL remains a challenge for scientists and clinicians due to insufficient biological knowledge, a lack of appropriate animal models and validated diagnostic biomarkers. We summarize recent findings on genomic, transcriptomic and epigenetic alterations identified in PCNSL. These findings help to define pathobiology of the disease and delineate defects in B cell differentiation. Evidence from genomic and transcriptomic studies helps to separate PCNSL from other hematological malignancies, improves diagnostics and reveals new therapeutic targets for treatment. Discovery of the CNS lymphatic system may be instrumental in better understanding the origin of the disease. We critically assess the attempts to model PCNSL in rodents, and conclude that there is a lack of a genetic/transgenic model that adequately mimics pathogenesis of the disease. Contribution of the tumor microenvironment in tumorigenesis and aggressiveness of PCNSL remains understudied. Assessing heterogeneity of immune infiltrates, cytokine profiling and molecular markers, may improve diagnostics and put forward new therapeutic strategies.

Blood Coagulation Factor Fibrinogen in Tumor Pathogenesis of Central Nervous System B-Cell Lymphoma

Central nervous system (CNS) lymphoma is an extranodal non-Hodgkin B-cell lymphoma characterized by malignant lymph tissue arising in the brain or spinal cord, associated with inflammation and blood-brain barrier (BBB) disruption. Although BBB disruption is known to occur in patients with CNS lymphoma, a direct link between these two has not been shown. Herein, abundant deposition of the blood coagulation protein fibrinogen around B-cell lymphoma was detected in CNS lymphoma patients and in the CNS parenchyma in an orthotopic mouse model. Functional enrichment analysis of unbiased cerebrospinal fluid proteomics of CNS B-cell lymphoma patients showed that coagulation protein networks were highly connected with tumor-associated biological signaling pathways. In vivo two-photon imaging demonstrated that lymphoma growth was associated with BBB disruption, and in vitro experiments identified a role for fibrinogen in promoting lymphoma cell adhesion. Overall, these results identify perivascular lymphoma clustering at sites of fibrinogen deposition, and suggest that fibrinogen may be a target for pharmacologic intervention in metastatic B-cell lymphoma associated with BBB disruption.

The immune contexture of primary central nervous system diffuse large B cell lymphoma associates with patient survival and specific cell signaling

Rationale: Primary central nervous system diffuse large B-cell lymphoma (PCNSL) is a rare and aggressive entity that resides in an immune-privileged site. The tumor microenvironment (TME) and the disruption of the immune surveillance influence lymphoma pathogenesis and immunotherapy resistance. Despite growing knowledge on heterogeneous therapeutic responses, no comprehensive description of the PCNSL TME is available. We hence investigated the immune subtypes of PCNSL and their association with molecular signaling and survival. Methods: Analysis of PCNSL transcriptomes (sequencing, n = 20; microarrays, n = 34). Integrated correlation analysis and signaling pathway topology enabled us to infer intercellular interactions. Immunohistopathology and digital imaging were used to validate bioinformatic results. Results: Transcriptomics revealed three immune subtypes: immune-rich, poor, and intermediate. The immune-rich subtype was associated to better survival and characterized by hyper-activation of STAT3 signaling and inflammatory signaling, e.g., IFNγ and TNF-α, resembling the hot subtype described in primary testicular lymphoma and solid cancer. WNT/β-catenin, HIPPO, and NOTCH signaling were hyper-activated in the immune-poor subtype. HLA down-modulation was clearly associated with a low or intermediate immune infiltration and the absence of T-cell activation. Moreover, HLA class I down-regulation was also correlated with worse survival with implications on immune-intermediate PCNSL that frequently feature reduced HLA expression. A ligand-receptor intercellular network revealed high expression of two immune checkpoints, i.e., CTLA-4/CD86 and TIM-3/LAGLS9. TIM-3 and galectin-9 proteins were clearly upregulated in PCNSL. Conclusion: Altogether, our study reveals that patient stratification according to immune subtypes, HLA status, and immune checkpoint molecule quantification should be considered prior to immune checkpoint inhibitor therapy. Moreover, TIM-3 protein should be considered an axis for future therapeutic development.

Primary Central Nervous System Lymphomas: A Diagnostic Overview of Key Histomorphologic, Immunophenotypic, and Genetic Features

Primary central nervous system lymphoma (PCNSL) is a rare form of extranodal non-Hodgkin lymphoma that primarily arises in the brain, spinal cord, leptomeninges, and vitreoretinal compartment of the eye. The term is sometimes used interchangeably with primary central nervous system diffuse large B-cell lymphoma (PCNS DLBCL) because DLBCL comprises a great majority (90–95%) of PCNSL. Although rare, other types of lymphomas can be seen in the central nervous system (CNS), and familiarity with these entities will help their recognition and further workup in order to establish the diagnosis. The latter is especially important in the case of PCNSL where procurement of diagnostic specimen is often challenging and yields scant tissue. In this review, we will discuss the most common types of primary lymphomas that can be seen in the CNS with emphasis on the diagnostic histomorphologic, immunophenotypic, and molecular genetic features. The differential diagnostic approach to these cases and potential pitfalls will also be discussed.

Molecular Subtypes and Genomic Profile of Primary Central Nervous System Lymphoma

Primary central nervous system lymphomas (PCNSL) are aggressive non-Hodgkin lymphomas affecting the central nervous system (CNS). Although immunophenotyping studies suggested an uniform activated B-cell (ABC) origin, more recently a spectrum of ABC and germinal center B-cell (GC) cases has been proposed, with the molecular subtypes of PCNSL still being a matter of debate. With the emergence of novel therapies demonstrating different efficacy between the ABC and GC patient groups, precise assignment of molecular subtype is becoming indispensable. To determine the molecular subtype of 77 PCNSL and 17 secondary CNS lymphoma patients, we used the NanoString Lymphoma Subtyping Test (LST), a gene expression-based assay representing a more accurate technique of subtyping compared with standard immunohistochemical (IHC) algorithms. Mutational landscapes of 14 target genes were determined using ultra-deep next-generation sequencing. Using the LST-assay, a significantly lower proportion (80% vs 95%) of PCNSL cases displayed ABC phenotype compared with the IHC-based characterization. The most frequently mutated genes included MYD88, PIM1, and KMT2D. In summary, we successfully applied the LST-assay for molecular classification of PCNSL, reporting higher proportion of cases with GC phenotype compared with IHC analyses, leading to a more precise patient stratification potentially applicable in the diagnostic algorithm of PCNSL.

Apparent diffusion coefficient as a valuable quantitative parameter for predicting clinical outcomes in patients with newly diagnosed primary CNS lymphoma

Background

This study attempted to identify novel prognostic factors in patients with newly diagnosed primary central nervous system lymphoma (PCNSL) using magnetic resonance imaging (MRI).

Methods

We retrospectively evaluated 67 patients diagnosed with central nervous system (CNS) tumors. The enrollment criteria were as follows: i) pathologic diagnosis of CNS lymphoma, ii) no evidence of systemic involvement, iii) no evidence of human immunodeficiency virus-1 infection or other immunodeficiencies, and iv) MRI scans available at diagnosis. Fifty-two patients met these criteria and were enrolled.

Results

The 3-year overall survival (OS) and failure-free survival rates were 69.7% and 45.6%, respectively, with a median follow-up duration of 36.2 months. OS of patients with low apparent diffusion coefficient (ADC) was lower than those with higher ADC. Multivariate analysis revealed that old age (>60 yr) [hazard ratio (HR), 20.372; P=0.001], Eastern Cooperative Oncology Group performance status (ECOG PS) ≥2 (HR, 10.429; P<0.001), higher lactate dehydrogenase (LDH) levels (HR, 7.408; P=0.001), and low ADC (HR, 0.273; P=0.009) were associated with lower OS. We modified the conventional prognostic scoring system using low ADC, old age (>60 yr), ECOG PS ≥2, and higher LDH. The risk of death was categorized as high (score 3-4), intermediate-2 (score 2), intermediate-1 (score 1), and low (score 0), with three-year OS rates of 33.5%, 55.4%, 88.9%, and 100%, respectively.

Conclusion

ADC demonstrated significant prognostic value for long-term survival in patients with newly diagnosed PCNSL. Low ADC was an independent unfavorable prognostic factor, suggesting that ADC obtained from MRI can improve the current prognostic scoring system.

Performance of diffusion and perfusion MRI in evaluating primary central nervous system lymphomas of different locations

Background

Diffusion and perfusion MRI can invasively define physical properties and angiogenic features of tumors, and guide the individual treatment. The purpose of this study was to investigate whether the diffusion and perfusion MRI parameters of primary central nervous system lymphomas (PCNSLs) are related to the tumor locations.

Methods

We retrospectively reviewed the diffusion, perfusion, and conventional MRI of 68 patients with PCNSLs at different locations (group 1: cortical gray matter, group 2: white matter, group 3: deep gray matter). Relative maximum cerebral blood volume (rCBV_max) from perfusion MRI, minimum apparent diffusion coefficients (ADC_min) from DWI of each group were calculated and compared by one-way ANOVA test. In addition, we compared the mean apparent diffusion coefficients (ADC_mean) in three different regions of control group.

Results

The rCBV_max of PCNSLs yielded the lowest value in the white matter group, and the highest value in the cortical gray matter group (P < 0.001). However, the ADC_min of each subgroup was not statistically different. The ADC_mean of each subgroup in control group was not statistically different.

Conclusion

Our study confirms that rCBV_max of PCNSLs are related to the tumor location, and provide simple but effective information for guiding the clinical practice of PCNSLs.

Molecular profiling of primary central nervous system lymphomas - predictive and prognostic value?

PURPOSE OF REVIEW

Primary central nervous system lymphoma (PCNSL) is a rare but aggressive variant of non-Hodgkin lymphoma. The diagnostic gold standard remains the pathologic review of tumor tissue mainly collected though biopsies. The majority of PCNSL are diffuse large B cell lymphoma (DLBCL). Biopsies are invasive procedures, and there have been efforts to develop minimally invasive diagnostic testing using serum and cerebral spinal fluid. This article reviews multiple markers that could potentially serve as future diagnostic tools and predictors of treatment response.

RECENT FINDINGS

Many studies have attempted to classify DLBCL into different subtypes for prognostic purposes using methods such as immunohistochemistry. PCNSL often falls under the activated B-cell-like subgroup, and further genomic sequencing has identified alterations in genes within the B-cell receptor signaling axis at increased frequencies. Two such genes, MYD88 and CD79B, implicate the involvement of the NF-kB (nuclear factor kappa-light-chain enhancer of activated B cells) pathway, and targeted agents to this pathway are currently being used in the treatment of relapsed/refractory PCNSL.

SUMMARY

Although recent genomic profiling of PCNSL has increased the understanding of drivers in this disease and has also led to the introduction of targeted inhibitors, these markers have not yet been used for diagnostic and/or prognostic purposes. Further studies will need to evaluate if they hold great diagnostic potential.

Epstein-Barr Virus Infection in the Development of Neurological Disorders

Epstein-Barr Virus (EBV) is a ubiquitous human herpesvirus that contributes to the etiology of diverse human cancers and auto-immune diseases. EBV establishes a relatively benign, long-term latent infection in over 90 percent of the adult population. Yet, it also increases risk for certain cancers and auto-immune disorders depending on complex viral, host, and environmental factors that are only partly understood. EBV latent infection is found predominantly in memory B-cells, but the natural infection cycle and pathological aberrations enable EBV to infect numerous other cell types, including oral, nasopharyngeal, and gastric epithelia, B-, T-, and NK-lymphoid cells, myocytes, adipocytes, astrocytes, and neurons. EBV infected cells, free virus, and gene products can also be found in the CNS. In addition to the direct effects of EBV on infected cells and tissue, the effect of chronic EBV infection on the immune system is also thought to contribute to pathogenesis, especially auto-immune disease. Here, we review properties of EBV infection that may shed light on its potential pathogenic role in neurological disorders.

Lymphomas arising in immune-privileged sites: insights into biology, diagnosis, and pathogenesis

Session 2 of the 2018 European Association of Hematopathology/Society for Hematopathology Workshop focused on lymphomas arising in immune-privileged sites: both lymphomas arising in the traditionally described "immune sanctuary" sites of the central nervous system (CNS) and testes, as well as those arising at sites of local immune privilege. Primary CNS large B cell lymphoma and primary testicular large B cell lymphoma were discussed, and the biology of these unique tumors was highlighted by several cases showing the classic mutation profile including MYD88 L265P and CD79B. The tendency of these tumors to involve both the CNS and testis was also reinforced by several cases. Four cases of low-grade B cell lymphomas (LGBCL) of the CNS were discussed. Two were classic Bing-Neel syndrome associated with LPL, and two were LGBCL with plasmacytic differentiation and amyloid deposition without systemic disease. Rare examples of systemic T and NK cell lymphomas involving the CNS were also discussed. Several cases of breast implant-associated anaplastic large cell lymphoma (BI-ALCL) were submitted showing the typical clinicopathologic features. These cases were discussed along with a case with analogous features arising in a patient with a gastric band implant, as well as large B cell lymphomas arising alongside foreign materials. Finally, large B cell lymphomas arising in effusions or localized sites of chronic inflammation (fibrin-associated diffuse large B cell lymphoma [DLBCL] and DLBCL associated with chronic inflammation) were described. The pathogenesis of all of these lymphomas is believed to be related to decreased immune surveillance, either innate to the physiology of the organ or acquired at a local site.

Safety, Diagnostic Accuracy, and Effects of Endoscopic Ultrasound Fine-Needle Aspiration on Detection of Extravascular Migratory Metastases

BACKGROUND & AIMS

Tumor cells can migrate via diminutive perivascular cuffing to distant sites along blood vessels to form extravascular migratory metastases (EVMM). These metastases usually are identified during surgery or autopsies. We aimed to evaluate the feasibility and safety of endoscopic ultrasound fine-needle aspiration (EUS-FNA) of perivascular soft-tissue cuffs to detect EVMM. We compared findings from EUS with those from noninvasive cross-sectional imaging (reference standard) of patients who underwent EUS-FNA to assess suspected EVMM and studied the effects on pancreatic tumor staging and determination of resectability.

METHODS

We performed a retrospective analysis of 253 patients (mean age, 62 ± 12 y) who underwent EUS-FNA of 267 vessels for evaluation of suspected EVMM, from April 2001 through May 2018. EUS findings were compared with those from computed tomography (CT) and magnetic resonance imaging (MRI) as the reference standard. Lesions were considered to be malignant based on cytology analysis of FNA samples, histology analyses of surgical or biopsy specimens, or vascular abnormalities detected by CT or MRI that clearly indicate EVMM.

RESULTS

Thirty patients were found to have benign lesions. The remaining 223 patients who had malignancies (166 with pancreatic ductal adenocarcinomas [PDACs]), underwent further analyses. A median of 4 FNAs (range, 1-20 FNAs) were obtained from 4-mm perivascular soft-tissue cuffs (range, 2-20 mm). FNA and cytology analysis showed malignant cells in 163 vessels (69.4%) from 157 patients (70.4%). CT or MRI did not detect EVMM in 44 patients (28%) with malignancies, including 24 patients (24%) with newly diagnosed PDAC. Detection of EVMM by EUS-FNA resulted in upstaging of 15 patients and conversion of 14 patients with PDAC from resectable (based on CT or MRI) to unresectable. No adverse events were reported during a follow-up period of 3.9 months (range, 0-117 mo).

CONCLUSIONS

EUS-FNA and cytologic analysis of perivascular soft-tissue cuffs can detect EVMM that were not found in 28% of patients by CT or MRI. Detection of EVMM affects tumor staging and determination of tumor resectability.

[CNS involvement and the feasibility of intratecal chemotherapy administration in patients with a nodal form of diffuse large B-cell lymphoma not otherwise specified. Data of prospective study]

Aim of the issue was to determine indications for intratecal chemotherapy drugs administration to prevent relapse of diffuse large B-cell lymphoma (DLBCL) with central nervous system (CNS) involvement.

MATERIALS AND METHODS

Since January 2009 to December 2018 102 patients with primary nodal DLBCL over 18 years old were treated in the National Research Center for Hematology, Moscow, Russian Federation. Diagnosis were established in all cases according to histological and immunohistochemical studies which made it possible to exclude the transformation of mature B-cell lymphoma into DLBCL.

RESULTS

Isolated leptomeningeal involvement of CNS in the debut of the disease was detected in 1 (0.98%) out of 102 patients with DLBCL. Focal brain tissue involvement was not detected in any patient. More than half of the patients (54%) had a high risk of disease recurrence or progression with CNS involvement: in 8 (7.8%) patients had kidney/adrenal involvement, in the same proportion - bone marrow involvement, paranasal sinuses involvement - in 5 (4.9 %), epidural space - in 7 (6.9%) and breast - in 5 (4.9%) of patients. In 82 (80%) patients, a non-GCB (postgerminal differentiation of B-cell analog) molecular subtype of DLBCL was determined.

CONCLUSION

The introduction of chemotherapy drugs into the spinal canal is recommended in isolated cases of leptomeningeal involvement of CNS at the time of DLBCL onset and is carried out according to standard recommendations. Prevention of relapse with involvement of central nervous system using intratecal chemotherapy in patients with nodal form of DLBCL is not indicated due to the absence of cases with disease progression or recurrence into CNS when patients were treated with R-m-NHL-BFM-90, R-DA-EPOCH and R-CHOP protocol.

Phase 1 investigation of lenalidomide/rituximab plus outcomes of lenalidomide maintenance in relapsed CNS lymphoma

There is an unmet need for effective biological therapies for relapsed central nervous system (CNS) lymphoma. Lenalidomide is active in activated B-cell type diffuse large B-cell lymphoma and rituximab is effective in CNS lymphoma. These observations are the basis for this first trial of an immunomodulatory drug as monotherapy in CNS lymphoma, and, in patients with inadequate responses to lenalidomide, with rituximab. In an independent cohort, we evaluated lenalidomide maintenance after salvage with high-dose methotrexate or focal irradiation in relapsed primary CNS lymphoma (PCNSL). We determined safety, efficacy, and cerebrospinal fluid (CSF) penetration of lenalidomide at 10-, 15-, and 20-mg dose levels in 14 patients with refractory CD20⁺ CNS lymphoma. Nine subjects with relapsed, refractory CNS lymphoma achieved better than partial response with lenalidomide monotherapy, 6 maintained response ≥9 months, and 4 maintained response ≥18 months. Median progression-free survival for lenalidomide/rituximab was 6 months. In the independent cohort, response duration with lenalidomide maintenance after complete responses 2 through 5 were significantly longer than response durations after standard therapy. The CSF/plasma partition coefficient of lenalidomide was ≥20% at 15- and 20-mg dose levels. Change in CSF interleukin-10 at 1 month correlated with clinical response and response duration to lenalidomide. Metabolomic profiling of CSF identified novel biomarkers, including lactate, and implicated indoleamine-2,3 dioxygenase activity with CNS lymphoma progression on lenalidomide. We conclude that lenalidomide penetrates ventricular CSF and is active as monotherapy in relapsed CNS lymphomas. We provide evidence that maintenance lenalidomide potentiates response duration after salvage in relapsed PCNSL and delays whole brain radiotherapy (WBRT). This trial was registered at www.clinicaltrials.gov as #NCT01542918.

MicroRNA signature constituted of miR-30d, miR-93, and miR-181b is a promising prognostic marker in primary central nervous system lymphoma

MicroRNAs (miRNAs) are small RNA molecules that inhibit gene function by suppressing translation of target genes. However, in primary central nervous system lymphoma (PCNSL), the biological significance of miRNAs is largely unknown, although some miRNAs are known to be prognosis markers. Here, we analyzed 847 miRNAs expressed in 27 PCNSL specimens using microarray profiling and surveyed miRNA signature for prognostic prediction. Of these, 16 miRNAs were expressed in 27 PCNSL specimens at a frequency of 48%. Their variable importance measured by Random forest model revealed miR-192, miR-486, miR-28, miR-52, miR-181b, miR-194, miR-197, miR-93, miR-708, and let-7g as having positive effects; miR-29b-2*, miR-126, and miR-182 as having negative effects; and miR-18a*, miR-425, and miR-30d as neutral. After principal component analysis, the prediction formula for prognosis, consisting of the expression values of the above-mentioned miRNAs, clearly divided Kaplan-Meier survival curves by the calculated Z-score (HR = 6.4566, P = 0.0067). The 16 miRNAs were enriched by gene ontology terms including angiogenesis, cell migration and proliferation, and apoptosis, in addition to signaling pathways including TGF-β/SMAD, Notch, TNF, and MAPKinase. Their target genes included BCL2-related genes, HMGA2 oncogene, and LIN28B cancer stem cell marker. Furthermore, three miRNAs including miR-181b, miR-30d, and miR-93, selected from the 16 miRNAs, also showed comparable results for survival (HR = 8.9342, P = 0.0007), suggestive of a miRNA signature for prognostic prediction in PCNSL. These results indicate that this miRNA signature is useful for prognostic prediction in PCNSL and would help us understand target pathways for therapies in PCNSL.

Primary Central Nervous System Lymphoma: Molecular Pathogenesis and Advances in Treatment

Primary central nervous system lymphoma (PCNSL) is a group of extranodal non-Hodgkin lymphoma that exhibits specific biological characteristics and clinical behavior, with an aggressive disease course and unsatisfactory patient outcomes. It is of great importance to identify aberrant genetic loci and important molecular pathways that might suggest potential targets for new therapeutics and provide prognostic information. In this review, we listed various genetic and epigenetic alterations that are involved in PCNSL pathogenesis. In the aspect of treatment, we summarized the related literatures and evaluated the efficacy of surgery, induction chemotherapy, radiotherapy, intrathecal chemotherapy, and autologous stem cell transplantation in PCNSL. We also proposed the possible new agents for recurrent and relapse PCNSL based on the result of recent clinical researches.

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.

Advances in Pathobiology of Primary Central Nervous System Lymphoma

Objective:

Primary central nervous system lymphoma (PCNSL) is a specific type of non-Hodgkin lymphoma with poor prognosis. The rare incidence of this disease and difficulty to obtain sufficient tissue material impede deep research into PCNSL. However, application of modern molecular techniques makes it possible to find biological characteristics exclusive to PCNSL. Therefore, we systematically reviewed the latest research progress on biological characteristics and pathogenesis of PCNSL.

Data Sources:

The data analyzed in this review were from the articles listed in PubMed database.

Study Selection:

Articles focusing on the biology of PCNSL at the cytogenetic or molecular level were reviewed, including clinical, basic research, and review articles.

Results:

With respect to histopathology, perivascular growth pattern and reactive perivascular T-cell infiltration are regarded as typical histopathological manifestations of tumor cells in PCNSL. Moreover, tumor cells of PCNSL predominantly express an activated B-cell-like phenotype, including CD10⁻ BCL-6⁺ MUM1⁺, CD10⁻ BCL-6⁻ MUM1⁺, and CD10⁻ BCL-6⁻ MUM1⁻. On the molecular level, some molecular and genetic alterations may contribute to malignant transformation, including mutations of proto-oncogenes and tumor suppressor genes, gains and losses of genetic material, as well as aberrant activation of some important signaling pathways, such as nuclear factor-κB and JAK/STAT pathway.

Conclusions:

The integrated molecular mechanisms involved in pathogenesis of PCNSL are not well understood. The important biomarkers indicating prognosis are not identified. Multicenter studies should be carried out to elucidate pathogenesis of PCNSL to find novel and effective therapeutic strategies.

Prognostic implications of tumor-infiltrating macrophages, M2 macrophages, regulatory T-cells, and indoleamine 2,3-dioxygenase-positive cells 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 an aggressive disease with a poor prognosis. The status of the tumor immune microenvironment in CNS-DLBCL remains unclear. We investigated the prognostic implications of tumor-associated macrophages (TAMs), regulatory T-cells (Tregs), and indoleamine 2,3-dioxygenase (IDO)⁺ cells in primary CNS-DLBCL (n = 114) by immunohistochemical analysis. The numbers of tumor-infiltrating immune cells, including CD68⁺ TAMs, CD163⁺ or CD204⁺ M2 macrophages, FOXP3⁺ Tregs, and IDO⁺ cells were all significantly lower in CNS-DLBCL versus systemic DLBCL (n = 165; all P < 0.001), but with little difference in the ratio of CD163⁺/CD68⁺ or CD204⁺/CD68⁺ cells. An increase in CD68⁺ cell numbers was significantly associated with prolonged progression-free survival (PFS) and overall survival in patients with CNS-DLBCL (P = 0.004 and 0.021, respectively). In contrast, an increase in CD204⁺ cell numbers or a higher ratio of CD204⁺/CD68⁺ cells was related to a shorter PFS (P = 0.020 and 0.063, respectively). An increase in IDO⁺ cell numbers was associated with a significantly longer PFS (P = 0.019). In combination, the status of low IDO⁺ cell numbers combined with low CD68⁺ cell numbers, high CD204⁺ cell numbers, or a high CD204⁺/CD68⁺ cell ratio all predicted poor PFS in multivariate analyses. This study showed that an increase in CD204⁺ cell numbers, suggestive of M2 macrophages, was associated with poor clinical outcome in CNS-DLBCL, whereas increased CD68⁺ or IDO⁺ cell numbers were related to a favorable prognosis. The analysis of tumor-infiltrating immune cells could help in predicting the prognosis of CNS-DLBCL patients and determining therapeutic strategies targeting tumor microenvironment.

Incidence and outcomes of primary central nervous system lymphoma in solid organ transplant recipients

Primary central nervous system lymphoma (PCNSL) risk is greatly increased in immunosuppressed human immunodeficiency virus-infected people. Using data from the US transplant registry linked with 17 cancer registries (1987-2014), we studied PCNSL and systemic non-Hodgkin lymphoma (NHL) in 288 029 solid organ transplant recipients. Transplant recipients had elevated incidence for PCNSL compared with the general population (standardized incidence ratio = 65.1; N = 168), and this elevation was stronger than for systemic NHL (standardized incidence ratio=11.5; N = 2043). Compared to kidney recipients, PCNSL incidence was lower in liver recipients (adjusted incidence rate ratio [aIRR] = 0.52), similar in heart and/or lung recipients, and higher in other/multiple organ recipients (aIRR = 2.45). PCNSL incidence was higher in Asians/Pacific Islanders than non-Hispanic whites (aIRR = 2.09); after induction immunosuppression with alemtuzumab (aIRR = 3.12), monoclonal antibodies (aIRR = 1.83), or polyclonal antibodies (aIRR = 2.03); in recipients who were Epstein-Barr virus-seronegative at the time of transplant and at risk of primary infection (aIRR = 1.95); and within the first 1.5 years after transplant. Compared to other recipients, those with PCNSL had increased risk of death (adjusted hazard ratio [aHR] = 11.79) or graft failure/retransplantation (aHR = 3.24). Recipients with PCNSL also had higher mortality than those with systemic NHL (aHR = 1.48). In conclusion, PCNSL risk is highly elevated among transplant recipients, and it carries a poor prognosis.

Targeting the perivascular niche in brain tumors

PURPOSE OF REVIEW

Brain tumors are composed of primary tumors of the central nervous system, such us glioblastoma (GBM), and secondary metastatic tumors, such as melanoma, non-Hodgkin lymphoma as well as lung and breast cancers. Brain tumors are highly deadly, and unfortunately not many improvements have been achieved to improve the survival of patients with brain tumors. Chemoradiation resistance is one of the most clinically relevant challenges faced in patients with brain tumors. The perivascular niche is one of the most relevant microenvironment hubs in brain tumors. The understanding of the cellular crosstalk established within the brain tumor perivascular niche might provide us with key discoveries of new brain tumor vulnerabilities.

RECENT FINDINGS

Radio and chemoresistance in GBM and brain metastases is attributed to cancer stem cells (CSCs), which intrinsically modulate several pathways that make them resistant to therapy. Growing evidence, however, highlights the perivascular space as a niche for CSC survival, resistance to therapy, progression and dissemination. Here, I review the latest discoveries on the components and features of brain tumor vascular niches and the possible therapeutic strategies aimed at targeting its vulnerabilities, thus preventing GBM and metastasis chemoradiation resistance and recurrence.

SUMMARY

Recent discoveries suggest that targeting the brain perivascular niche has the potential of sensitizing brain tumors to therapies and reducing the occurrence of metastases.

Biology of CNS lymphoma and the potential of novel agents

Primary and secondary CNS lymphomas are aggressive brain tumors that pose an immense challenge to define in terms of molecular pathogenesis, as well as to effectively treat. During the past 10 years improvements in survival have been achieved with the implementation of anti-CD20 immunotherapy and optimization of dose-intensive consolidation strategies. The applications of whole-exome sequencing, comparative genomic hybridization, transcriptional profiling, and examination of the tumor microenvironment, particularly in the context of clinical investigation, provide insights that create a roadmap for the development and implementation of novel targeted agents for this disease. A body of genetic evidence strongly suggested that primary CNS lymphomas (PCNSLs) are likely largely dependent on NF-κB prosurvival signals, with enrichment of mutations involving the B-cell receptor pathway, in particular myeloid differentiation primary response 88 and cluster of differentiation 79B. The first set of early-phase investigations that target NF-κB in PCNSL have now been completed and support the NF-κB hypothesis but at the same time reveal that much work needs to be done to translate these results into meaningful advances in survival for a large fraction of patients. Insights into secondary prosurvival pathways that mediate drug resistance is a priority for investigation. Similarly, further evaluation of the immune-suppressive mechanisms in the CNS lymphoma tumor microenvironment is requisite for progress. Combinatorial interventions that promote the antitumor immune response have significant potential. With increasing availability of targeted agents, there is also a need to develop more sensitive imaging tools, not only to detect this highly invasive brain neoplasm but also potentially to define an evolving molecular phenotype to facilitate precision medicine.

The Challenge of Primary Central Nervous System Lymphoma

Primary central nervous system (CNS) lymphoma is a challenging subtypes of aggressive non-Hodgkin lymphoma. Emerging clinical data suggest that optimized outcomes are achieved with dose-intensive CNS-penetrant chemotherapy and avoiding whole brain radiotherapy. Anti-CD20 antibody-based immunotherapy as a component of high-dose methotrexate-based induction programs may contribute to improved outcomes. An accumulation of insights into the molecular and cellular basis of disease pathogenesis is providing a foundation for the generation of molecular tools to facilitate diagnosis as well as a roadmap for integration of targeted therapy within the developing therapeutic armamentarium for this challenging brain tumor.

Primary central nervous system lymphoma: essential points in diagnosis and management

Primary central nervous system lymphoma (PCNSL) is an extra-nodal non-Hodgkin lymphoma. PCNSL is defined as lymphoma involving the brain, leptomeninges, eyes, or spinal cord without evidence of lymphoma outside the CNS. Treatment includes induction with chemotherapy and consolidation with whole-brain radiotherapy or high-dose chemotherapy supported by autologous stem cell transplantation. High-dose methotrexate is the most important drug in cases with PCNSL, and this drug will be used in combination with small molecules, BTK inhibitors, new monoclonal antibodies, and checkpoint blockers.

Prognostic impact of MYC protein expression in central nervous system diffuse large B-cell lymphoma: comparison with MYC rearrangement and MYC mRNA expression

The prognostic role of MYC has been well documented in non-central nervous system diffuse large B-cell lymphoma; however, it remains controversial in central nervous system diffuse large B-cell lymphoma. To investigate the prognostic value of MYC, we analyzed the MYC protein expression by immunohistochemistry, mRNA expression by RNA in situ hybridization, and gene status by fluorescence in situ hybridization in 74 cases of central nervous system diffuse large B-cell lymphoma. Moreover, we examined the correlation between MYC translocation, mRNA expression, and protein expression. The mean percentage of MYC immunopositive cells was 49%. Using a 44% cutoff value, 49 (66%) cases showed MYC protein overexpression. The result of mRNA in situ hybridization using the RNA scope technology was obtained using the H-scoring system; the median value was 34.2. Using the cutoff value of 63.5, 16 (22%) cases showed MYC mRNA overexpression. MYC gene rearrangement was detected in five out of 68 (7%) cases. MYC translocation showed no statistically significant correlation with mRNA expression; however, all MYC translocation-positive cases showed MYC protein overexpression, with a higher mean percentage of MYC protein expression than that of translocation-negative cases (78 vs 48%, P=0.001). The level of MYC mRNA expression was moderately correlated with the level of MYC protein expression (P<0.001). The mean percentage of MYC protein expression in the high MYC mRNA group was higher than that in the low MYC mRNA group (70 vs 47%, P<0.001). A univariate analysis showed that age over 60 years, Eastern Cooperative Oncology Group (ECOG) performance status ≥2 and MYC protein overexpression were significantly associated with an increased risk of death. MYC translocation and MYC mRNA expression had no prognostic significance. On multivariate analysis, MYC protein overexpression and ECOG score retained prognostic significance.

Canine Nervous System Lymphoma Subtypes Display Characteristic Neuroanatomical Patterns

Primary and secondary nervous system involvement occurs in 4% and 5%–12%, respectively, of all canine non-Hodgkin lymphomas. The recent new classification of canine malignant lymphomas, based on the human World Health Organization classification, has been endorsed with international acceptance. This histological and immunocytochemical classification provides a unique opportunity to study the histologic anatomic distribution patterns in the central and peripheral nervous system of these defined lymphoma subtypes. In this study, we studied a cohort of 37 dogs with lymphoma, which at necropsy had either primary (n = 1, 2.7%) or secondary (n = 36; 97.3%) neural involvement. These T- (n = 16; 43.2%) or B-cell (n = 21; 56.8%) lymphomas were further classified into 12 lymphoma subtypes, with predominant subtypes including peripheral T-cell lymphoma (PTCL) or diffuse large B-cell lymphoma (DLBCL), respectively. This systematic study identified 6 different anatomically based histologically defined patterns of lymphoma infiltration in the nervous system of dogs. Different and distinct combinations of anatomical patterns correlated with specific lymphoma subtypes. Lymphoma infiltration within the meningeal, perivascular, and periventricular compartments were characteristic of DLBCL, whereas peripheral nerve involvement was a frequent feature of PTCL. Similarly cell counts above 64 cells/μL in cerebrospinal samples correlated best with marked meningeal and periventricular lymphoma infiltration histologically. Prospective studies are needed in order to confirm the hypothesis that these combinations of histological neuroanatomic patterns reflect targeting of receptors specific for the lymphoma subtypes at these various sites.

Primary intracranial lymphomas

BACKGROUND

Primary CNS lymphoma (PCNSL), a rare form of aggressive extranodal non-Hodgkin's lymphoma (NHL), has increased in incidence during the last three decades and occurs in both immune compromised and immune competent hosts. It has an overall poor prognosis.

OBJECTIVE

This study attempts to further delineate the clinico-pathological, immunohistochemical and radiological profile of PCNSL at Jeddah to King Faisal Hospital and Research Center.

METHODS

Computerized search through the archives of King Faisal Hospital and Research Centre between July 2000- December 2012 identified 15 patients with pathologically confirmed PCNSL. These were analyzed retrospectively. Their clinico-pathological, immunohistochemical and radiological data were analyzed.

RESULTS

Of the 15 PCNSL patients, 8 (53.3%) were females and 7 (46.6%) were males. There was female predilection especially in the age group of 40-59 years. Mean age at diagnosis for all patients was 50.4 years. There was no patient in the pediatric age group. The most common location in the brain was the frontal region in 7 patients (46.6%), 7 (46.6%) had multiple intracranial masses; all 15 (100%) were Non Hodgkin B-cell lymphomas, among which 13 (86.6%) were diffuse large B-cell lymphomas. All 15 (100%) cases showed diffuse and strong positivity for CD 45, and CD 20. Fourteen patients were immune competent while one was immune compromised.

CONCLUSIONS

PCNSL often occurs in middle-aged and aged patients. There is female predilection especially in the middle age. Frontal region is the most common location with diffuse large B-cell lymphoma being the predominant subtype.

New approaches in primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) has long been associated with an inferior prognosis compared to other aggressive non-Hodgkin's lymphomas (NHLs). However, during the past 10 years an accumulation of clinical experience has demonstrated that long-term progression-free survival (PFS) can be attained in a major proportion of PCNSL patients who receive dose-intensive consolidation chemotherapy and avoid whole brain radiotherapy. One recent approach that has reproducibly demonstrated efficacy for newly diagnosed PCNSL patients is an immunochemotherapy combination regimen used during induction that consists of methotrexate, temozolomide, and rituximab followed by consolidative infusional etoposide plus high-dose cytarabine (EA), administered in first complete remission (CR). Other high-dose chemotherapy-based consolidative regimens have shown efficacy as well. Our goal in this review is to update principles of diagnosis and management as well as data regarding the molecular pathogenesis of PCNSL, information that may constitute a basis for development of more effective therapies required to make additional advances in this phenotype of aggressive NHL.

Primary central nervous system lymphomas and related diseases: Pathological characteristics and discussion of the differential diagnosis

Although primary diffuse large B-cell lymphomas of the CNS are designated as primary CNS lymphomas according to the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissue in 2008, a variety of other lymphomas (Burkitt lymphomas, EBV-positive diffuse large B-cell lymphoma of the elderly) and related diseases (lymphomatoid granulomatosis) that are also found in the CNS have been spotlighted in recent years. The histopathology of primary CNS Burkitt lymphomas mimics that of primary diffuse large B-cell lymphomas of the CNS after steroid administration. Therefore, for correct diagnosis of the involved lymphoma, comprehensive fluorescent in situ hybridization analysis for c-MYC and BCL2 is recommended in all primary CNS lymphoma cases with aggressive clinical course, multifocal involvement of the CNS, and a high proliferation index. The pathological characteristics of primary CNS EBV-positive diffuse large B-cell lymphoma of the elderly have similarities with those of the latency phenotype III, EBV lymphoproliferative disorders that arise in the setting of immunodeficiency. These age-related lymphomas usually occur in elderly immunocompetent patients, and the incidence of this disease was estimated to range from 4.0% to 13.6% of all primary CNS lymphomas. Shorter overall survival has been reported for patients with this disease. Lymphomatoid granulomatosis (LYG) is a systemic, EBV-driven, angiocentric and angiodestructive lymphoproliferative disorder. Primary LYG that shows distinct clinicopathological features compared with systemic LYG was recently reported. Finally, this review focuses on the relationship between primary CNS lymphomas and demyelinating diseases, and the concomitant use of intraoperative cytology and frozen sections that are helpful in rapid intraoperative diagnosis.