Microenvironment-centred dynamics in aggressive B-cell lymphomas

αvβ3 Integrin Expression and Mitogenic Effects by Thyroid Hormones in Chronic Lymphocytic Leukemia

Background: Chronic lymphocytic leukemia (CLL) is the most common adult leukemia. The thyroid hormones, T3 and T4, bind the αvβ3 integrin and activate phosphorylates ERK (pERK). These tumor-promoting actions were reported in a number of malignancies, but not in CLL. Methods: Primary cells from 22 CLL patients were verified for disease markers (CD5/CD19/CD23) and analyzed for αvβ3 by flow cytometry (FC), ImageStream, Western blots (WB), and immunohistochemistry (IHC) in archival bone marrow (BM, n = 6) and lymph node (LN, n = 5) tissues. Selected samples (n = 8) were incubated with T3 (1–100 nM) or T4 (0.1–10 µM) for 30 min, and the expression levels of αvβ3, pERK and PCNA (cell proliferation marker) were determined (WB). Results: αvβ3 was detected on the membrane of circulating CLL cells and in the BM but not in the LN. T3 and T4 enhanced αvβ3 protein levels in primary CLL cells. Similarly, pERK and PCNA were rapidly induced in response to T3 and T4 exposure. Conclusions: αvβ3 integrin is expressed on primary CLL cells and is induced by thyroid hormones. We further suggest that the hormones are mitogenic in these cells, presumably via αvβ3-mediated signaling.

The Tumor Microenvironment of DLBCL in the Computational Era

Among classical exemplifications of tumor microenvironment (TME) in lymphoma pathogenesis, the “effacement model” resembled by diffuse large B cell lymphoma (DLBCL) implies strong cell autonomous survival and paucity of non-malignant elements. Nonetheless, the magnitude of TME exploration is increasing as novel technologies allow the high-resolution discrimination of cellular and extra-cellular determinants at the functional, more than morphological, level. Results from genomic-scale studies and recent clinical trials revitalized the interest in this field, prompting the use of new tools to dissect DLBCL composition and reveal novel prognostic association. Here we revisited major controversies related to TME in DLBCL, focusing on the use of bioinformatics to mine transcriptomic data and provide new insights to be translated into the clinical setting.

Advancing CAR T-Cell Therapy for Solid Tumors: Lessons Learned from Lymphoma Treatment

Chimeric antigen receptor (CAR) immunotherapy is one of the most promising modern approaches for the treatment of cancer. To date only two CAR T-cell products, Kymriah^® and Yescarta^®, have been approved by the Food and Drug Administration (FDA) for the treatment of lymphoblastic leukemia and B-cell lymphoma. Administration of CAR T-cells to control solid tumors has long been envisaged as one of the most difficult therapeutic tasks. The first two clinical trials conducted in sarcoma and neuroblastoma patients showed clinical benefits of CAR T-cells, yet multiple obstacles still hold us back from having accessible and efficient therapy. Why did such an effective treatment for relapsed and refractory hematological malignancies demonstrate only relatively modest efficiency in the context of solid tumors? Is it due to the lucky selection of the “magic” CD19 antigen, which might be one of a kind? Or do lymphomas lack the immunosuppressive features of solid tumors? Here we review the existing knowledge in the field of CAR T-cell therapy and address the heterogeneity of solid tumors and their diverse strategies of immunoevasion. We also provide an insight into prospective developments of CAR T-cell technologies against solid tumors.

Tumor Microenvironment in Diffuse Large B-Cell Lymphoma: Role and Prognosis

Diffuse large B-cell lymphoma (DLBCL) represents 30-40% of all non-Hodgkin lymphomas (NHL) and is a disease with an aggressive behavior. Because about one-third of DLBCL patients will be refractory or resistant to standard therapy, several studies focused on identification of new individual prognostic and risk stratification biomarkers and new potential therapeutic targets. In contrast to other types of cancers like carcinomas, where tumor microenvironment was widely investigated, its role in DLBCL pathogenesis and patient survival is still poorly understood, although few studies had promising results. The composition of TME and its interaction with neoplastic cells may explain the role of several genes (beta2-microglobulin gene, CD58 gene), receptor-like programmed cell death-1 (PD-1) and its ligand (PD-L1), or other cell components (Treg) in tumor evasion of immune surveillance, resulting in tumor progression. Also, it was found that “gene expression profile” of the microenvironmental cells, the phenotype of tumor-associated macrophages (TAM), the expression of matricellular proteins like SPARC and fibronectin, the overexpression of several types of matrix metalloproteinases (MMPs) like MMP-2 and MMP-9, or the tissue inhibitors of matrix metalloproteinases (TIMPs) may lead to a favorable or adverse outcome. With this review, we try to highlight the influence of microenvironment components over lymphoid clone progression and their prognostic impact in DLBCL patients.

RNAscope dual ISH-IHC technology to study angiogenesis in diffuse large B-cell lymphomas

Diffuse large B-cell lymphomas (DLBCLs) are the most common types of Non-Hodgkin's lymphomas and are highly heterogeneous in terms of phenotype and treatment response. The natural course of DLBCLs tumor progression is featured by a flow of events leading to the enhancement of proliferative and invasive capabilities and, therefore, towards the establishment of a more aggressive phenotype. Angiogenesis is a constant hallmark of DLBCLs progression, has prognostic potential and promote DLBCLs dissemination. The study of DLBCLs angiogenesis mechanisms, and the tumor endothelium characterization, will allow us to identify new prognostic/predictive biomarkers to proper patient selection to antiangiogenic treatment. In our previous work, by RNAscope technology, we have demonstrated that Janus kinase (Jak) and signal transducer activator of transcription pathway (STAT) is one of the proangiogenic pathways activated in DLBCLs and it drives neoangiogenesis occurred by vasculogenesis mechanism. Here, we describe a detailed protocol to perform RNAscope technology alone and in combination with immunohistochemistry (called dual RNAscope ISH-IHC) in DLBCLs formalin-fixed, paraffin-embedded sections. We propose dual ISH-IHC as an extremely powerful method to study angiogenesis in DLBCLs, because it allows one to answer important biological questions that are difficult to address using other single methods.

Dissection of DLBCL microenvironment provides a gene expression-based predictor of survival applicable to formalin-fixed paraffin-embedded tissue

Background

Gene expression profiling (GEP) studies recognized a prognostic role for tumor microenvironment (TME) in diffuse large B-cell lymphoma (DLBCL), but the routinely adoption of prognostic stromal signatures remains limited.

Patients and methods

Here, we applied the computational method CIBERSORT to generate a 1028-gene matrix incorporating signatures of 17 immune and stromal cytotypes. Then, we carried out a deconvolution on publicly available GEP data of 482 untreated DLBCLs to reveal associations between clinical outcomes and proportions of putative tumor-infiltrating cell types. Forty-five genes related to peculiar prognostic cytotypes were selected and their expression digitally quantified by NanoString technology on a validation set of 175 formalin-fixed, paraffin-embedded DLBCLs from two randomized trials. Data from an unsupervised clustering analysis were used to build a model of clustering assignment, whose prognostic value was also assessed on an independent cohort of 40 cases. All tissue samples consisted of pretreatment biopsies of advanced-stage DLBCLs treated by comparable R-CHOP/R-CHOP-like regimens.

Results

In silico analysis demonstrated that higher proportion of myofibroblasts (MFs), dendritic cells, and CD4⁺ T cells correlated with better outcomes and the expression of genes in our panel is associated with a risk of overall and progression-free survival. In a multivariate Cox model, the microenvironment genes retained high prognostic performance independently of the cell-of-origin (COO), and integration of the two prognosticators (COO + TME) improved survival prediction in both validation set and independent cohort. Moreover, the major contribution of MF-related genes to the panel and Gene Set Enrichment Analysis suggested a strong influence of extracellular matrix determinants in DLBCL biology.

Conclusions

Our study identified new prognostic categories of DLBCL, providing an easy-to-apply gene panel that powerfully predicts patients’ survival. Moreover, owing to its relationship with specific stromal and immune components, the panel may acquire a predictive relevance in clinical trials exploring new drugs with known impact on TME.

Concurrent Elevations of VEGF, Osteopontin and MCP-1 Serum Levels Are Independent Predictors of Survival in Patients with Diffuse Large B-Cell Lymphoma

BACKGROUND

Diffuse large B-cell lymphomas (DLBCL) are heterogeneous diseases, and the identification of additional DLBCL risk factors is especially important.

METHODS

In this pilot study, we determined pretreatment serum levels of vascular endothelial growth factor (VEGF), osteopontin (OPN) and macrophage chemotactic protein-1 (MCP-1) in 67 newly diagnosed DLBCL patients before treatment with standard chemoimmunotherapy and in 30 healthy persons.

RESULTS

Serum levels of all three cytokines were significantly elevated in untreated patients compared to controls. VEGF and OPN concentrations were higher in patients with advanced Ann Arbor stage, B symptoms, Eastern Cooperative Oncology Group score ≥2, International Prognostic Index (IPI) ≥3 and partial/no remission. A high MCP-1 level was associated with advanced stage, increased IPI and bone marrow infiltration. In univariate analysis, elevated OPN and VEGF, and concurrent elevation of all three biomarkers, were identified as significant predictors of poor survival. Multivariate Cox analysis revealed that elevated OPN combined with elevated VEGF levels was one of the best parameter subsets predicting poorest survival.

CONCLUSION

According to our preliminary results, serum levels of VEGF and OPN before treatment predict response to therapy and survival after chemoimmunotherapy, and may help to further stratify DLBCL patients into risk groups.

The tumor microenvironment shapes hallmarks of mature B-cell malignancies

B-cell tumorigenesis results from a host of known and unknown genetic anomalies, including non-random translocations of genes that normally function as determinants of cell proliferation or cell survival to regions juxtaposed to active immunoglobulin heavy chain enhancer elements, chromosomal aneuploidy, somatic mutations that further affect oncogenic signaling and loss of heterozygosity of tumor-suppressor genes. However, it is critical to recognize that even in the setting of a genetic disease, the B-cell/plasma cell tumor microenvironment (TME) contributes significantly to malignant transformation and pathogenesis. Over a decade ago, we proposed the concept of cell adhesion-mediated drug resistance to delineate a form of TME-mediated drug resistance that protects hematopoietic tumor cells from the initial effect of diverse therapies. In the interim, it has been increasingly appreciated that TME also contributes to tumor initiation and progression through sustained growth/proliferation, self-renewal capacity, immune evasion, migration and invasion as well as resistance to cell death in a host of B-cell malignancies, including mantle cell lymphoma, diffuse large B-cell lymphoma, Waldenstroms macroglobulinemia, chronic lymphocytic leukemia and multiple myeloma. Within this review, we propose that TME and the tumor co-evolve as a consequence of bidirectional signaling networks. As such, TME represents an important target and should be considered integral to tumor progression and drug response.

Stromal niche communalities underscore the contribution of the matricellular protein SPARC to B-cell development and lymphoid malignancies

Neoplastic B-cell clones commonly arise within secondary lymphoid organs (SLO). However, during disease progression, lymphomatous cells may also colonize the bone marrow (BM), where they localize within specialized stromal niches, namely the osteoblastic and the vascular niche, according to their germinal center- or extra-follicular-derivation, respectively. We hypothesized the existence of common stromal motifs in BM and SLO B-cell lymphoid niches involved in licensing normal B-cell development as well as in fostering transformed B lymphoid cells. Thus, we tested the expression of prototypical mesenchymal stromal cell (MSC) markers and regulatory matricellular proteins in human BM and SLO under physiologically unperturbed conditions and during B-cell lymphoma occurrence. We identified common stromal features in the BM osteoblastic niche and SLO germinal center (GC) microenvironments, traits that were also enriched within BM infiltrates of GC-associated B-cell lymphomas, suggesting that stromal programs involved in central and peripheral B-cell lymphopoiesis are also involved in malignant B-cell nurturing. Among factors co-expressed by stromal elements within these different specialized niches, we identified the pleiotropic matricellular protein secreted protein acidic and rich in cysteine (SPARC). The actual role of stromal SPARC in normal B-cell lymphopoiesis, investigated in Sparc-/- mice and BM chimeras retaining the Sparc-/- genotype in host stroma, demonstrated defective BM and splenic B-cell lymphopoiesis. Moreover, in the Trp53 knockout (KO) lymphoma model, p53-/-/Sparc-/- double-KO mice displayed impaired spontaneous splenic B-cell lymphomagenesis and reduced neoplastic clone BM infiltration in comparison with their p53-/-/Sparc+/+ counterparts. Our results are among the first to demonstrate the existence of common stromal programs regulating both the BM osteoblastic niche and the SLO GC lymphopoietic functions potentially fostering the genesis and progression of B-cell malignancies.

Bone marrow stroma CD40 expression correlates with inflammatory mast cell infiltration and disease progression in splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is a mature B-cell neoplasm characterized by rather indolent clinical course. However, nearly one third of patients experience a rapidly progressive disease with a dismal outcome. Despite the characterization of clone genetics and the recognition of deregulated immunologic stimulation in the pathogenesis of SMZL, little is known about microenvironment dynamics and their potential biological influence on disease outcome. Here we investigate the effect of stroma-intrinsic features on SMZL disease progression by focusing on the microenvironment of the bone marrow (BM), which represents an elective disease localization endorsing diagnostic and prognostic relevance. We show that the quality of the BM stromal meshwork of SMZL infiltrates correlates with time to progression. In particular, we describe the unfavorable prognostic influence of dense CD40 expression by BM stromal cells, which involves the contribution of CD40 ligand (CD40L)-expressing bystander mast cells infiltrating SMZL BM aggregates. The CD40/CD40L-assisted crosstalk between mesenchymal stromal cells and mast cells populating the SMZL microenvironment finds correlation in p53(-/-) mice developing SMZL and contributes to the engendering of detrimental proinflammatory conditions. Our study highlights a dynamic interaction, playing between nonneoplastic elements within the SMZL niche, toward disease progression.

Bone marrow trephine biopsy involvement by lymphoma: review of histopathological features in 511 specimens and correlation with diagnostic biopsy, aspirate and peripheral blood findings

AIMS

This study aimed to evaluate the key features of bone marrow trephine (BMT) biopsy involvement by lymphoma.

METHODS

511 cases were assessed for percentage of marrow involvement, pattern of involvement (diffuse, nodular, paratrabecular, interstitial or intrasinusoidal), presence/absence of granulomas, stromal fibrosis and necrosis, presence/absence of neoplastic/reactive follicles and discordance with other biopsy sites. Correlation with aspirate and peripheral blood findings was made in a subset of 345 patients (167 aspirates, 178 blood).

RESULTS

The most frequent subtype was follicular lymphoma (26.2%) followed by extranodal marginal zone (23.1%), lymphoplasmacytic (19.2%), diffuse large B cell (DLBCL) (12.5%), Hodgkin (HL) (5.7%) and mantle cell lymphomas (4.3%). The predominant pattern in follicular lymphoma was paratrabecular. Marginal zone lymphomas of all types and lymphoplasmacytic lymphoma showed a relatively even distribution between diffuse, interstitial, paratrabecular and nodular patterns. The majority of mantle cell lymphoma cases showed either diffuse or nodular patterns. A diffuse pattern was common in DLBCL and Burkitt lymphomas. An intrasinusoidal pattern was seen only in extranodal and splenic marginal zone lymphomas. Granulomas and fibrosis were uncommon in small cell B cell lymphomas but frequent in DLBCL and HL. Aspirate and trephine results concurred in 73.8% of cases overall, but this varied widely between subtypes. Peripheral blood involvement rates by lymphoma also varied, with a mean of 37.1%.

CONCLUSIONS

Different lymphomas often demonstrate reliably characteristic architectural patterns of marrow involvement which can help differentiate them even when cytological features do not permit this, and marrow stromal and other background changes may also be useful pointers towards a particular lymphoma subtype.

Epstein-Barr virus presence in pediatric diffuse large B-cell lymphoma reveals a particular association and latency patterns: analysis of viral role in tumor microenvironment

Non-Hodgkin's lymphoma represents 6-10% of pediatric malignancies, and diffuse large B-cell lymphoma (DLBCL) is one of the three major subtypes. The 2008 WHO classification included a new entity, Epstein-Barr virus (EBV)-positive DLBCL of the elderly, affecting patients >50 years. It has been demonstrated that EBV may play a role in tumor microenvironment composition, disturbing antitumor immune response and disease progression. As most studies were performed in adults, our aim was to assess EBV presence and latency pattern, as well as T-cell microenvironment in a pediatric DLBCL series of Argentina. The study was conducted on formalin-fixed paraffin-embedded biopsies from 25 DLBCL patients. EBV-encoded small nuclear early regions (EBERs) expression was performed by in situ hybridization, whereas EBV gene expression was analyzed using real-time PCR. Epstein-Barr virus latent membrane proteins (LMP)1, LMP2A, CD3, CD4, CD8 and Foxp3 expression were assessed by immunohistochemistry (IHC). Forty percent of cases showed EBV expression, with a significantly higher incidence among patients <10 years (p = 0.018), and with immunosuppressed (p = 0.023). T-cell subsets were not altered by EBV presence. Full EBV latency antigen expression (latency type III) was the most frequently pattern observed, together with BZLF1 lytic gene expression. One patient showed II-like pattern (LMP1 without LMP2A expression). Based exclusively on IHC, some patients showed latency II/III (EBERs and LMP1 expression) or I (EBERs only). These findings suggest that EBV association in our series was higher than the previously demonstrated for elderly DLBCL and that EBV latency pattern could be more complex from those previously observed. Therefore, EBV could be an important cofactor in pediatric DLBCL lymphomagenesis.