Genetics and Pathogenesis of Diffuse Large B-Cell Lymphoma

Phosphoproteomic Analysis of Signaling Pathways in Lymphomas

Cellular fate is regulated by intricate signal transduction mediated by posttranslational protein modifications like phosphorylation to transmit information. As other cancer types, lymphomas frequently show dysregulation of signaling pathways that contribute to malignant transformation and tumor progression. For example, in diffuse large B-cell lymphoma the B-cell antigen receptor was identified as an oncogenic driver mediating cellular growth and survival signals. Thus, the elucidation of these complex signaling networks is crucial to gain insight into the mechanisms underlying tumorigenesis and to identify target proteins for innovative therapeutic approaches.Here, we describe a mass spectrometry-based phosphoproteomic approach for the global analysis of intracellular signaling events and their dynamics. The workflow combines phosphopeptide enrichment and fractionation with liquid chromatography-coupled mass spectrometry for the amino acid site-specific identification and quantification of thousands of phosphorylation events. Such global signaling analyses have great potential for the elucidation of oncogenic pathomechanisms, diagnostic biomarkers, and drug targets.

Genetic Manipulation and Extended Culture of Human Germinal Center B Cells to Model Lymphomagenesis

The germinal center (GC) is the stage of B cell differentiation that gives rise to a majority of B cell lymphomas. Here, we present an experimental coculture system for the ex vivo expansion and genetic manipulation of human GC B cells purified from discarded tonsil tissue. This system can be used to investigate the impact of defined genetic alterations, either individually or in combination, upon the growth and survival of human GC B cells in vitro. We provide examples of genetic combinations that lead to the immortalized growth of GC B cells in vitro, and others that result in malignant transformation in immunodeficient mice, allowing the creation of genetically bespoke, synthetic, human lymphoma models.

Genetic Mouse Models of Lymphomas

Mouse models are an indispensable tool in lymphoma research. Here, we focus on the utilization of genetically engineered mouse models as preclinical avatars in lymphoma research. We describe lymphoma-relevant alleles and allele combinations, as well as general considerations for model selection. We further illustrate concepts of gene targeting and model design and provide guidelines for breeding strategies and colony maintenance.

B Cell Differentiation and the Origin and Pathogenesis of Human B Cell Lymphomas

Immunoglobulin (IG) gene remodeling by V(D)J recombination plays a central role in the generation of normal B cells, and somatic hypermutation and class switching of IG genes are key processes during antigen-driven B cell differentiation in the germinal center reaction. However, errors of these processes are involved in the development of B cell lymphomas. IG locus-associated translocations of proto-oncogenes are a hallmark of many B cell malignancies. Additional transforming events include inactivating mutations in various tumor suppressor genes and also latent infection of B cells with viruses, such as Epstein-Barr virus. Most B cell lymphomas require B cell antigen receptor expression, and in several instances chronic antigenic stimulation plays a role in lymphoma development and/or sustaining tumor growth. Often, survival and proliferation signals provided by other cells in the microenvironment are a further critical factor in lymphoma development and pathophysiology. Most B cell malignancies derive from germinal center B cells, most likely due to the high proliferative activity of these B cells and aberrant mutations caused by their naturally active mutagenic processes.

Tafasitamab for the treatment of patients with diffuse large B-cell lymphoma

Patients with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL) require additional treatments, especially those not eligible or not responding to high dose cytotoxic chemotherapy and stem cell transplantation. Over the last few years, several new treatments have been developed and approved for these patients, among them of particular relevance are those targeting CD19. Tafasitamab is a humanized monoclonal antibody targeting CD19, composed of a modified fragment crystallizable (Fc) region engineered with higher affinity for Fc gamma receptors (FcγR) receptors, leading to increased cytotoxicity through natural killer cells and macrophages (antibody-dependent cellular cytotoxicity and antibody-dependent cell-mediated phagocytosis). In this product review, we will discuss its mechanism of action, safety profile and efficacy results from clinical trials that led to its approval in combination with lenalidomide for patients with R/R DLBCL ineligible for high-dose chemotherapy and autologous transplantation.

An interpretable survival model for diffuse large B-cell lymphoma patients using a biologically informed visible neural network

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL) and is characterized by high heterogeneity. Assessment of its prognosis and genetic subtyping hold significant clinical implications. However, existing DLBCL prognostic models are mainly based on transcriptomic profiles, while genetic variation detection is more commonly used in clinical practice. In addition, current clustering-based subtyping methods mostly focus on genes with high mutation frequencies, providing insufficient explanations for the heterogeneity of DLBCL. Here, we proposed VNNSurv (https://bio-web1.nscc-gz.cn/app/VNNSurv), a survival model for DLBCL patients based on a biologically informed visible neural network (VNN). VNNSurv achieved an average C-index of 0.72 on the cross-validation set (HMRN cohort, n = 928), outperforming the baseline methods. The remarkable interpretability of VNNSurv facilitated the identification of the most impactful genes and the underlying pathways through which they act on patient outcomes. When only the 30 highest-impact genes were used as genetic input, the overall performance of VNNSurv improved, and a C-index of 0.70 was achieved on the external TCGA cohort (n = 48). Leveraging these high-impact genes, including 16 genes with low (<5 %) alteration frequencies, we devised a genetic-based prognostic index (GPI) for risk stratification and a subtype identification method. We stratified the patient group according to the International Prognostic Index (IPI) into three risk grades with significant prognostic differences. Furthermore, the defined subtypes exhibited greater prognostic consistency than clustering-based methods. Broadly, VNNSurv is a valuable DLBCL survival model. Its high interpretability has significant value for precision medicine, and its framework is scalable to other diseases.

Clinicopathological characteristics and genomic profiling in patients with transformed lymphoma: a monocentric retrospective study

BACKGROUND

Transformed lymphoma occurs when indolent lymphoma transforms into more aggressive lymphoma usually associated with poor prognosis.

METHODS

In this study, we analysed the immunophenotypes, prognostic factors and outcomes of 35 patients with transformed lymphoma from among 306 marginal zone lymphoma (MZL), 544 follicular lymphoma (FL) and 871 chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) cases. In addition, we performed whole-exome sequencing study of seven transformed MZL (tMZL) cases.

RESULTS

Our results demonstrate that the median time from indolent lymphoma diagnosis to transformed DLBCL was 35 months (range, 14-53 months). The 5-year overall survival (OS) and progression-free survival (PFS) rates after histological transformation (HT) were 50% and 26%, respectively. Kaplan-Meier survival analysis revealed that asynchronous HT and transformed CLL/SLL (tCLL/SLL) were significant adverse prognostic factors for OS after DLBCL HT. We identified mutations involvement in chromatin remodelling (CREBBP and EP300) and regulators of NF-κB signalling (TNFAIP3, BCL10, MYD88, CD79B and CARD11) were affected in tMZL.

CONCLUSION

Whole-exome sequencing and copy-number analysis revealed that tMZL derives from the divergent evolution of an ancestral common progenitor clone (CPC). Collectively, this study provides clinicopathological characteristics of three common types of transformed lymphomas and the genetic profile of tMZL with diagnostic and therapeutic implications.

Prognostic value of lactate dehydrogenase, serum albumin and the lactate dehydrogenase/albumin ratio in patients with diffuse large B-cell lymphoma

OBJECTIVE

To investigate the prognostic value of lactate dehydrogenase (LDH), serum albumin (ALB) and the lactate dehydrogenase/albumin ratio (LAR) in diffuse large B-cell lymphoma (DLBCL) before primary treatment.

METHODS

The clinical data of 212 primary adult DLBCL patients admitted to the First People's Hospital of Lianyungang from January 2017 to December 2022 were analyzed retrospectively. The optimal cutoff values of LDH, ALB, and LAR were determined using ROC curves. Survival curves of LDH, ALB, and LAR were plotted and analyzed using the Cox regression model and Kaplan-Meier method with the log-rank test.

RESULTS

Among the 212 patients admitted, the study derived the optimal cutoff values for ALB, LDH, and LAR as 38, 301, and 6, respectively. The Kaplan-Meier method and log-rank test analysis indicated a significant association between lower ALB levels, elevated LDH levels, elevated LAR levels, and shorter overall survival (OS) and progression-free survival (PFS) (P < 0.05). Additionally, the critical values of ALB and LDH were grouped into three categories. The differences in OS and PFS among these three groups were statistically significant (P < 0.05). Cox multifactorial analysis revealed that the LAR was an independent factor influencing the prognosis of OS and PFS, with a higher prognostic value than LDH and ALB alone.

CONCLUSION

Decreased ALB levels and elevated LDH and LAR levels at the time of initial diagnosis are indicative of a poor prognosis in DLBCL patients. Furthermore, the study highlighted that the LAR has a higher prognostic value than LDH and ALB alone.

The role of lncRNA binding to RNA‑binding proteins to regulate mRNA stability in cancer progression and drug resistance mechanisms (Review)

Cancer is a disease that poses a serious threat to human health, the occurrence and development of which involves complex molecular mechanisms. Long non‑coding RNAs (lncRNAs) and RNA‑binding proteins (RBPs) are important regulatory molecules within cells, which have garnered extensive attention in cancer research in recent years. The binding of lncRNAs and RBPs plays a crucial role in the post‑transcriptional regulation of mRNA, affecting the synthesis of proteins related to cancer by regulating the stability of mRNA. This, in turn, regulates the malignant biological behaviors of tumor cells, such as proliferation and metastasis, and serves an important role in therapeutic resistance. The present study reviewed the role of lncRNA‑RBP interactions in the regulation of mRNA stability in various malignant tumors, with a focus on the molecular mechanisms underlying this regulatory interaction. The aim of the present review was to gain a deeper understanding of these molecular mechanisms to provide new strategies and insights for the precise treatment of cancer.

Cytoplasmic Lipid Droplets Predict Worse Prognosis in Diffuse Large B-Cell Lymphoma: Next-Generation Sequencing Deciphering Lipogenic Genes

Burkitt lymphoma is characterized by high cell turnover and numerous cytoplasmic vacuoles that are demonstrated to be lipid droplets (LDs) decorated by adipophilin. By contrast, cytoplasmic vacuoles are variably observed in diffuse large B-cell lymphoma (DLBCL) and less well characterized. In this study, we first validated in DLBCL that cytoplasmic vacuoles are indeed LDs by Oil-red-O stain, Bodipy fluorescent stain, and electron microscopy. Second, in a cohort of DLBCL patients (n=52) we showed that LDs in effusional lymphoma cells were associated with a poorer prognosis ( P =0.029, log-rank test) and higher International Prognostic Index (IPI) score (94% vs. 66%, P =0.026) than those without. Moreover, using adipophilin as a surrogate marker for LDs, we found in another cohort of biopsy specimen (n=85) that expression of adipophilin by lymphoma cells predicted a poorer prognosis ( P =0.007, log-rank test) and higher IPI score (63% vs. 30%, P =0.005). In addition, whole exome sequencing of effusional DLBCL cells showed LD-positive DLBCL shared genetic features with the MCD ( MYD88 and CD79B mutations) subtype and highlighted OSBPL10 and CUBN as the most frequently mutated genes involved in lipogenesis. Whole transcriptome analysis by comparing effusional DLBCL cells with versus without LDs showed upregulation of EHHADH , SLC1A1 , CD96 , INPP4B , and RNF183 relevant for lymphoma lipogenesis and upregulation of epithelial-mesenchymal transition and KRAS signaling pathways. Higher expression of EHHADH and CD96 were validated in LD-positive clinical samples and LD-rich cell lines than LD-poor cells along with the known lipogenic gene, FASN . Our findings highlight the roles of LDs and adipophilin expression in DLBCL, suggest that these markers may predict prognosis and show that lipogenic genes may be potential therapeutic targets.

Clinicopathological and Molecular Characteristics of Rare EBV-associated Diffuse Large B-cell Lymphoma With IRF4 Rearrangement

Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) is a rare form of aggressive B-cell lymphoma with limited molecular information reported regarding interferon regulatory factor 4 ( IRF4 ) status. Here, we presented 3 EBV-positive DLBCL cases with IRF4 rearrangement (EBV+DLBCL- IRF4 -R) verified by fluorescence in situ hybridization (FISH). Three patients, including 1 male and 2 females (median age: 64 y; range: 45 to 68 y), had normal immune function. During a median follow-up of 12 months (range: 0 to 24 mo), 2 patients succumbed to the disease, and 1 patient achieved complete response. Three tumors were present in the mediastinum, stomach, and thalamus, respectively. All three tumors exhibited DLBCL morphology and were identified as the non-germinal center B-cell subtype, with EBV-encoded small RNA positivity ranging from 70% to 80%. RNA sequencing was able to identify RHOH and IGH as fusion partners of IRF4 in two cases. No MYC and BCL2 rearrangements were detected in 3 cases by FISH and RNA sequencing. Next-generation sequencing revealed a low mutation burden, and only IRF4 was recurrently mutated in two EBV+DLBCL- IRF4 -R cases. Using the LymphGen 2.0 classifier, 1 case was classified as the MCD (including MYD88L265P and CD79B mutations) subtype. We report rare EBV+DLBCL- IRF4 -R that may enhance our understanding of the diverse spectrum of large B-cell lymphoma.

N-Glycan Branching Regulates BTLA Opposite to PD-1 to Limit T Cell Hyperactivity Induced by Branching Deficiency

N-glycan branching is a potent and multifaceted negative regulator of proinflammatory T cell and B cell function. By promoting multivalent galectin-glycoprotein lattice formation at the cell surface, branching regulates clustering and/or endocytosis of the TCR complex (TCR+CD4/CD8), CD45, CD25, BCR, TLR2 and TLR4 to inhibit T cell and B cell activation/proliferation and proinflammatory TH1 and TH17 over TH2 and induced T regulatory cell responses. In addition, branching promotes cell surface retention of the growth inhibitory receptor CTLA-4. However, the role of N-glycan branching in regulating cell surface levels of other checkpoint receptors such as BTLA (B and T lymphocyte attenuator) and PD-1 (programmed cell death protein 1) is unknown. In this study, we report that whereas branching significantly enhances PD-1 cell surface expression by reducing loss from endocytosis, the opposite occurs with BTLA in both T cells and B cells. T cell hyperactivity induced by branching deficiency was opposed by BTLA ligation proportional to increased BTLA expression. Other members of the BTLA/HVEM (herpesvirus entry mediator) signaling axis in T cells, including HVEM, LIGHT, and CD160, are largely unaltered by branching. Thus, branching-mediated endocytosis of BTLA is opposite of branching-induced inhibition of PD-1 endocytosis. In this manner, branching deficiency-induced upregulation of BTLA appears to serve as a checkpoint to limit extreme T cell hyperactivity and proinflammatory outcomes in T cells with low branching.

Sequencing of therapy for patients with diffuse large B-cell lymphoma in the era of novel drugs

Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive lymphoma, accounting for ~40% of all cases in adults. Whilst approximately two-thirds of DLBCL patients can be cured by first-line therapy, one-third of patients are primary refractory or relapse after an initial response (r/r DLBCL). Recent advances in the treatment of DLBCL have been achieved by a plethora of novel drugs, such as monoclonal antibodies, antibody-drug conjugates (ADC), bi-specific T-cell engagers (BITEs), and CD-19 directed chimeric antigen receptor (CAR)-T-cell therapies. The increasing number of therapeutic options significantly improved the outcome of patients; however, the therapeutic algorithm has become increasingly complex. In this review, we provide an overview of novel therapies for DLBCL patients and potential treatment sequencing from first to second, third, and later lines.

CD70 is a potential prognostic marker and significantly regulates cellular function in diffuse large B-cell lymphoma

Extensive research has demonstrated that dysregulation of costimulatory molecule expression plays a pivotal role in cancer biology. However, the impact of intratumoral CD70 on the initiation, progression, and immune response in diffuse large B-cell lymphoma (DLBCL) remains poorly understood. This study aims to elucidate the clinical significance of CD70 in DLBCL diagnosis and prognosis, as well as its relationship with the immune microenvironment. We first analyzed CD70 expression across various cancers, including DLBCL, using multiple online databases (TIMER, GEPIA, GENT2, TNMPlot, GSCA, and GEO). We then evaluated the clinical correlations and prognostic value of CD70 in DLBCL. Additionally, we investigated the functional role of CD70 in DLBCL cells. Genomic alterations of CD70 were analyzed using the cBioPortal online tool. Co-expression network analysis was performed to assess the biological functions associated with CD70. Furthermore, we utilized TIMER2.0 to examine the correlation between CD70 expression and immune cell infiltration. Our results revealed that CD70 expression was significantly upregulated in DLBCL tissues compared to matched normal tissues, and high CD70 expression was associated with poor clinical outcomes in DLBCL patients. In vitro experiments demonstrated that CD70 inhibition promotes apoptosis and induces G1 phase arrest in DLBCL cells. Genomic alteration analysis showed that patients with CD70 alterations exhibited worse overall survival compared to those without such alterations. Co-expression and functional enrichment analyses indicated that CD70 is functionally related to tumor necrosis factor receptor binding and the NF-κB signaling pathway. Moreover, we found that CD70 expression levels were negatively correlated with B cell and NK cell infiltration in DLBCL. In conclusion, this study suggests that CD70 is a potential diagnostic and therapeutic biomarker for DLBCL. Our findings provide valuable insights for the development of novel therapeutic strategies targeting CD70 in DLBCL treatment.

Efficacy and Safety of Ibrutinib as Monotherapy or Combination Therapy in Relapsed/Refractory Diffuse Large B-cell Lymphoma (R/R DLBCL): A Systematic Review and Meta-analysis

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is a highly heterogeneous disease group. Ibrutinib's monotherapy or combination therapy is effective in relapsed/refractory (R/R) DLBCL. However, the treatment response in R/R DLBCL varies from 15% to 90% with different regimens, and the tolerance remains controversial.

AREAS OF UNCERTAINTY

The efficacy and safety of ibrutinib monotherapy or combination therapy in patients with R/R DLBCL remain uncertain.

DATA SOURCES

The PubMed, CBM, MEDLINE, Cochrane Library, and Embase databases were searched from their inception to July 2021.

THERAPEUTIC ADVANCES

The total complete remission rate (CRR) and overall response rate in R/R DLBCL patients treated with ibrutinib were 26% and 49%, respectively. The CRR of ibrutinib combination therapy was significantly higher than the ibrutinib monotherapy (45% vs. 19%). Moreover, the CRR of patients was 40% in double expressing lymphoma, 35% in central nervous system lymphoma, and 33% in nongerminal center B-cell-like (non-GCB) DLBCL, which was higher than the 8% in those with the GCB subtype. The pooled median PFS and overall survival were 5.57 and 10.17 months, respectively. GCB-DLBCL had the worst overall survival (5.1 months). Nevertheless, we found that combination regimens had no survival advantage compared with monotherapy (P > 0.05), indicating that combination therapy was only a transitional treatment and bridge for chimeric antigen receptor T cells or other treatments. Moreover, 12% of patients on ibrutinib combination therapy had ≥grade 3 adverse events compared with 9% on ibrutinib monotherapy.

CONCLUSIONS

Ibrutinib monotherapy or combination therapy was safe and effective in treating R/R DLBCL with tolerable adverse reactions.

Synergistic effect of venetoclax and ibrutinib on ibrutinib-resistant ABC-type DLBCL cells

Despite the widespread use of R-CHOP therapy in diffuse large B-cell lymphoma (DLBCL), the therapeutic efficacy for this disease remains suboptimal, primarily due to the heterogeneity of refractory and/or relapsed diseases. To address this challenge, optimization of DLBCL treatment regimens has focused on the strategy of combining an additional drug "X" with R-CHOP to enhance efficacy. However, the failure of R-CHOP combined with the BTK inhibitor ibrutinib in treating ABC-type DLBCL patients has raised significant concerns regarding ibrutinib resistance. While some studies suggest that venetoclax may synergize with ibrutinib to kill ibrutinib-resistant cells, the underlying mechanisms remain unclear. Our study aimed to validate the enhanced tumor-suppressive effect of combining ibrutinib with venetoclax against ibrutinib-resistant cells and elucidate its potential mechanisms. Our experimental results demonstrated that ibrutinib-resistant cells exhibited significant cytotoxicity to the combination therapy of ibrutinib and venetoclax, inducing cell apoptosis through activation of the mitochondrial pathway and inhibition of aerobic respiration. Furthermore, we validated the inhibitory effect of this combination therapy on tumor growth in in vivo models. Therefore, our study proposes that the combination therapy of ibrutinib and venetoclax is a promising treatment strategy that can be applied in clinical practice for ABC-type DLBCL, offering a new solution to overcome the urgent challenge of ibrutinib resistance.

Histomorphologic spectrum of nodal marginal zone lymphoma as defined by its methylome

OBJECTIVES

Primary nodal marginal B-cell lymphoma (NMZL) is rare and histologically very variable. Its large-cell presentation is difficult to distinguish from nodal diffuse large B-cell lymphoma (nDLBCL) due to the absence of specific markers for nodal marginal zone lymphomas in general.

METHODS

Using a comprehensive cohort of NMZLs and a control cohort of nDLBCLs, we conducted a methylome analysis on subgroups of both.

RESULTS

The methylomes were strikingly different between the cohorts but unexpectedly homogeneous within the NMZL cohort. This allowed us to describe the morphologic spectrum of NMZL in all its value ranges. The considerable overlap in growth pattern and cytology of NMZL with nDLBCL was explored morphometrically, leading to an operational tool for separating both by a simple measurement of cell size and nuclear size. This was integrated in a hierarchical approach, including a scoring system for the parameter growth pattern, follicular colonization, follicular dendritic network, IgD expression, and Ki-67 rate, and led to a proposal for a classifier that we present here.

CONCLUSIONS

This methylome-based study extends the morphological spectrum of NMZL towards large cell morphology and offers a conventional way to distinguish it from nDLBCL.

SETD1B mutations confer apoptosis resistance and BCL2 independence in B cell lymphoma

The translocation t(14;18) activates BCL2 and is considered the initiating genetic lesion in most follicular lymphomas (FL). Surprisingly, FL patients fail to respond to the BCL2 inhibitor, Venetoclax. We show that mutations and deletions affecting the histone lysine methyltransferase SETD1B (KMT2G) occur in 7% of FLs and 16% of diffuse large B cell lymphomas (DLBCL). Deficiency in SETD1B confers striking resistance to Venetoclax and an experimental MCL-1 inhibitor. SETD1B also acts as a tumor suppressor and cooperates with the loss of KMT2D in lymphoma development in vivo. Consistently, loss of SETD1B in human lymphomas typically coincides with loss of KMT2D. Mechanistically, SETD1B is required for the expression of several proapoptotic BCL2 family proteins. Conversely, inhibitors of the KDM5 histone H3K4 demethylases restore BIM and BIK expression and synergize with Venetoclax in SETD1B-deficient lymphomas. These results establish SETD1B as an epigenetic regulator of cell death and reveal a pharmacological strategy to augment Venetoclax sensitivity in lymphoma.

MYC-rearranged mature B-cell lymphomas in children and young adults are molecularly Burkitt Lymphoma

Aggressive B-cell non-Hodgkin lymphomas (NHL) in children, adolescents, and young adults (CAYA) include Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL), and a subset of high-grade tumors with features intermediate between these entities whose genetic and molecular profiles have not been completely elucidated. In this study, we have characterized 37 aggressive B-NHL in CAYA, 33 with high-grade morphology, and 4 DLBCL with MYC rearrangement (MYC-R), using targeted next-generation sequencing and the aggressive lymphoma gene expression germinal center B-cell-like (GCB), activated B-cell-like (ABC), and dark zone signatures (DZsig). Twenty-two tumors had MYC-R without BCL2 breaks, and two MYC-non-R cases had BCL6 translocations. MYC-R cases, including DLBCL, carried BL-related mutations and copy number alterations. Conversely, MYC-non-R lymphomas had alterations in the B-cell receptor signaling/NF-κB pathway (71%). DZsig was expressed in 12/13 of MYC-R tumors but only in 2/10 of MYC-non-R GCB tumors (P < 0.001). The 3-year event-free survival (EFS) of the whole cohort was 79.6%. TP53 and KMT2C mutations conferred inferior outcome (3-year EFS P < 0.05). Overall, MYC-R lymphomas in CAYA have a molecular profile similar to BL regardless of their high-grade or DLBCL morphology, whereas MYC-non-R has more heterogeneous genetic alterations closer to that of DLBCL.

Relocalizing transcriptional kinases to activate apoptosis

Kinases are critical regulators of cellular function that are commonly implicated in the mechanisms underlying disease. Most drugs that target kinases are molecules that inhibit their catalytic activity, but here we used chemically induced proximity to convert kinase inhibitors into activators of therapeutic genes. We synthesized bivalent molecules that link ligands of the transcription factor B cell lymphoma 6 (BCL6) to inhibitors of cyclin-dependent kinases (CDKs). These molecules relocalized CDK9 to BCL6-bound DNA and directed phosphorylation of RNA polymerase II. The resulting expression of pro-apoptotic, BCL6-target genes caused killing of diffuse large B cell lymphoma cells and specific ablation of the BCL6-regulated germinal center response. Genomics and proteomics corroborated a gain-of-function mechanism in which global kinase activity was not inhibited but rather redirected. Thus, kinase inhibitors can be used to context-specifically activate transcription.

EZB-type diffuse large B-cell lymphoma cell lines have superior migration capabilities compared to MCD-type

Diffuse large B-cell lymphoma (DLBCL) represents the most prevalent aggressive B-cell lymphoma. The group is heterogeneous and the outcome is variable. A variety of approaches have been employed with the objective of improving the stratification of DLBCL patients according to their prognosis, based on the cell of origin. Recently, distinct genetic subtypes of DLBCL have been identified. Given the importance of cell migration in immune cells, the objective of this study was to ascertain whether different genetic subtypes of DLBCL exhibit disparate migration abilities. MCD- and EZB-type DLBCL cell lines were subjected to testing to ascertain their basal velocity in straight microchannels and their ability to overcome tight constrictions of 2 μm. The EZB-type cell lines showed superior basal migration velocity and constriction passage time, and a similar trend was observed in live cell imaging of native human DLBCL tissue. In addition, MCD-type DLBCL exhibited significantly elevated levels of nuclear lamin A/C, which is responsible for the stiffness of the nuclear envelope and could thus explain the disparate migration behaviours observed among these subtypes. Our study suggests that different genetic subtypes of DLBCL may not only influence the outcome after therapy but also the motility of the tumour cells.

GNAS knockout potentiates HDAC3 inhibition through viral mimicry-related interferon responses in lymphoma

Despite selective HDAC3 inhibition showing promise in a subset of lymphomas with CREBBP mutations, wild-type tumors generally exhibit resistance. Here, using unbiased genome-wide CRISPR screening, we identify GNAS knockout (KO) as a sensitizer of resistant lymphoma cells to HDAC3 inhibition. Mechanistically, GNAS KO-induced sensitization is independent of the canonical G-protein activities but unexpectedly mediated by viral mimicry-related interferon (IFN) responses, characterized by TBK1 and IRF3 activation, double-stranded RNA formation, and transposable element (TE) expression. GNAS KO additionally synergizes with HDAC3 inhibition to enhance CD8+ T cell-induced cytotoxicity. Moreover, we observe in human lymphoma patients that low GNAS expression is associated with high baseline TE expression and upregulated IFN signaling and shares common disrupted biological activities with GNAS KO in histone modification, mRNA processing, and transcriptional regulation. Collectively, our findings establish an unprecedented link between HDAC3 inhibition and viral mimicry in lymphoma. We suggest low GNAS expression as a potential biomarker that reflects viral mimicry priming for enhanced response to HDAC3 inhibition in the clinical treatment of lymphoma, especially the CREBBP wild-type cases.

Benefit of consolidative radiation in patients with extranodal limited-stage diffuse large B-cell lymphoma: a multicenter retrospective study in China

Approximately 40% of limited-stage (stage I and II) diffuse large B-cell lymphoma (LS-DLBCL) presents with extranodal disease. Extranodal LS-DLBCL may have significant biological differences and associated with worse outcomes than nodal disease. Although rituximab based chemoimmunotherapy is standard of first-line treatment, the role of consolidative radiotherapy (RT) in this particular subgroup is controversial. In this multicenter retrospective study, we evaluated the survival benefit of consolidative RT in patients diagnosed with extranodal LS-DLBCL and received rituximab-based chemoimmunotherapy with or without consolidative RT. A total of 328 patients were included, 129 patients (39.3%) received chemoimmunotherapy and consolidative RT, and 199 patients (60.7%) received chemoimmunotherapy alone. With a median follow-up of 5.1 years (range, 0.3-14.8 years), 5-year progression-free survival (PFS) and overall survival (OS) for all patients were 75.4% and 83.9%, respectively. In multivariate analyses, the addition of consolidative RT was associated with superior OS (P = 0.004) and PFS (P = 0.005). High stage-modified International Prognosis Index (SM-IPI) risk predicted worse OS (P = 0.001) and PFS (P = 0.005). Also, propensity score-matched analyses showed RT improved both OS (hazard ratio [HR] 0.228, 95% confidence index [CI] 0.111-0.467, P < 0.001) and PFS (HR 0.308, 95% CI 0.167-0.566, P < 0.001). Among patients who achieved CR, 49 patients (16.6%) developed disease relapse, of which 30.6% relapsed at local sites. Consolidative RT significantly reduced relapse risk (P = 0.002). Our results demonstrated that consolidative RT significantly improved outcomes in patients with extranodal LS-DLBCL in the rituximab era.

Natural killer cell-associated prognosis model characterizes immune landscape and treatment efficacy of diffuse large B cell lymphoma

PURPOSE

NK cells are essential for the detection, identification and prediction of cancer. However, so far, there is no prognostic risk model based on NK cell-related genes to predict the prognosis and treatment outcome of DLBCL patients. This study aimed to explore a risk assessment model that could accurately predict the prognosis and treatment efficacy of DLBCL.

METHODS

Bioinformatics analysis of the expression profiles of DLBCL samples in the GEO database was performed. Cox regression and LASSO regression analysis were used to determine NK cell-related genes associated with patient's prognosis. Based on these genes, a risk assessment model was constructed to predict the prognosis of patients and the effectiveness of treatment. Finally, qRT-PCR was used to verify the expression of gene tags in clinical samples.

RESULTS

We identified seven prognosis-related NK cell-related genes (MAP2K1, PRKCB, TNFRSF10B, IL18, LAMP1, RASGRP1, and SP110), and DLBCL patients were divided into low- and high-risk groups based on these genes. Survival analysis showed that the prognosis of patients with low-risk group was better. Pathway enrichment analysis showed that the differentially expressed genes between the two risk groups were related to immune response pathways. Compared with the high-risk group, the low-risk group had higher infiltration of immune cells in tumor tissues. Besides, compared with high-risk group, low-risk patients by immunotherapy or other commonly used anti-tumor drugs might have better efficacy after treatment. In addition, qRT-PCR showed that the expression of risk genes including TNFRSF10B, IL18 and LAMP1 were significantly increased in most DLBCL samples compared to control samples, while the expression of protective genes including MAP2K1, PRKCB, RASGRP1 and SP110 were significantly decreased.

CONCLUSION

The NK cell-related gene signatures were proved to be a reliable indicator of the success of immunotherapy in patients with DLBCL, thus providing a unique evaluation method.

Opening and changing: mammalian SWI/SNF complexes in organ development and carcinogenesis

The switch/sucrose non-fermentable (SWI/SNF) subfamily are evolutionarily conserved, ATP-dependent chromatin-remodelling complexes that alter nucleosome position and regulate a spectrum of nuclear processes, including gene expression, DNA replication, DNA damage repair, genome stability and tumour suppression. These complexes, through their ATP-dependent chromatin remodelling, contribute to the dynamic regulation of genetic information and the maintenance of cellular processes essential for normal cellular function and overall genomic integrity. Mutations in SWI/SNF subunits are detected in 25% of human malignancies, indicating that efficient functioning of this complex is required to prevent tumourigenesis in diverse tissues. During development, SWI/SNF subunits help establish and maintain gene expression patterns essential for proper cellular identity and function, including maintenance of lineage-specific enhancers. Moreover, specific molecular signatures associated with SWI/SNF mutations, including disruption of SWI/SNF activity at enhancers, evasion of G0 cell cycle arrest, induction of cellular plasticity through pro-oncogene activation and Polycomb group (PcG) complex antagonism, are linked to the initiation and progression of carcinogenesis. Here, we review the molecular insights into the aetiology of human malignancies driven by disruption of the SWI/SNF complex and correlate these mechanisms to their developmental functions. Finally, we discuss the therapeutic potential of targeting SWI/SNF subunits in cancer.

Identification, risk factors, and clinical course of CNS relapse in DLBCL patients across 19 prospective phase 2 and 3 trials-a LYSA and GLA/ DSHNHL collaboration

Progression or relapse in the central nervous system (CNS) remains a rare but mostly fatal event for patients with diffuse large B-cell lymphoma (DLBCL). In a retrospective analysis of 5189 patients treated within 19 prospective German and French phase 2/3 trials, we identified 159 patients experiencing a CNS event (relapse: 62%, progression: 38%). Intracerebral, meningeal, intraspinal, or combined involvement was reported in 44%, 31%, 3%, and 22% of patients, respectively. 62 of 155 evaluable patients (40%) showed concurrent systemic progression/ relapse. 82% of all CNS events occurred within two years after study inclusion or randomization. 87% of patients showed extranodal involvement outside the CNS. Patients generally had poor outcomes with a median overall survival (OS) of 3.4 months (95% CI 2.9-4.2) and a 2-year OS of 15% (10-22%). Outcomes did not differ depending on the site or time point of CNS events. Patients with isolated CNS events demonstrated significantly better OS (p = 0.023). Twenty-five patients were consolidated with autologous or allogeneic stem cell transplantation and achieved a 3-year OS of 36% (20-66%). This large study including more than 5000 DLBCL patients highlights the unmet medical need to improve the outcome of DLBCL patients suffering from CNS relapse.

Morphology and multiparameter flow cytometry combined for integrated lymphoma diagnosis on small volume samples: possibilities and limitations

The diagnosis of lymphoma relies mainly on clinical examination and laboratory explorations. Among the latter, morphological and immunohistochemical analysis of a tissue biopsy are the cornerstones for proper identification and classification of the disease. In lymphoma with blood and/or bone marrow involvement, multiparameter flow cytometry is useful. This technique can also be applied to fresh cells released from a biopsy sample. For full comprehension of lymphomas, surgical biopsies are best and indeed recommended by the hematopathological community. Currently, however, there is a global trend towards less invasive procedures, resulting in smaller samples such as core needle biopsies or fine needle aspirations which can make the diagnosis quite challenging. In this review, the possibilities and limitations to make an accurate lymphoma diagnosis on such small volume material are presented. After recalling the major steps of lymphoma diagnosis, the respective value of histology, cytology, and flow cytometry is discussed, including handling of small specimens. The benefits of an integrated approach are then evoked, followed by discussion about which attitude to adopt in different contexts. Perhaps contrary to the prevailing view among many pathologists, a full diagnosis on small volume material, combined with relevant ancillary techniques, is often possible and indeed supported by recent literature. A glimpse at future evolutions, notably the merit of artificial intelligence tools, is finally provided. All in all, this document aims at providing pathologists with an overview of diagnostic possibilities in lymphoma patients when confronted with small volume material such as core needle biopsies or fine needle aspirations.

Primary breast diffuse large B-cell lymphoma characterized by CNS relapse and successful hematopoietic stem cell transplantation salvage therapy

BACKGROUND

Primary breast diffuse large B-cell lymphoma (PB-DLBCL) is rare, with a high incidence of central nervous system (CNS) relapse. This study aims to investigate clinical characteristics, prognostic factors, and outcomes in Taiwanese PB-DLBCL patients and review the literature on PB-DLBCL.

METHODS

Thirty-one PB-DLBCL patients diagnosed between 2000 and 2021 were retrospectively enrolled for analysis.

RESULTS

The median age was 49 (range 26-79) years. The complete remission (CR) rate was 90.3%. Nine (90%) of the ten patients who experienced relapse had CNS involvement at the time of relapse. The one-year, two-year, and five-year progression-free survival (PFS) rates were 86.6% (95% confidence interval [CI] 75.2-99.8), 75.8% (95% CI 61.6-93.2), and 45.1% (95% CI 29.5-68.9), respectively. The five-year overall survival (OS) rate was 64.1% (95 % CI 48.4-85.0). A stage-modified International Prognostic Index (mIPI) less than two (five-year PFS rate 52.5% vs. 17.1%, P = 0.02) and the achievement of CR after first-line treatment (two-year PFS rate 80.3% vs. 33.3%, P < 0.001) were significant favorable prognostic factors for PFS. Hematopoietic stem cell transplantation (HSCT) after the first relapse was associated with significantly improved post-relapse OS (five-year OS rate 85.7% vs. 20.0%, P = 0.02) and PFS (five-year PFS rate 85.7% vs. 20.0%, P = 0.02).

CONCLUSION

Patients with low-risk mIPI scores, CR after first-line treatment, and those who underwent HSCT after the first relapse had significantly better survival. Intrathecal chemotherapy conferred no benefit in preventing CNS relapse. Further research is needed to assess frontline HSCT's effectiveness in improving outcomes and preventing CNS relapses in PB-DLBCL patients.

Decreased PU.1 expression in mature B cells induces lymphomagenesis

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of lymphoma, accounting for 30% of non-Hodgkin lymphomas. Although comprehensive analysis of genetic abnormalities has led to the classification of lymphomas, the exact mechanism of lymphomagenesis remains elusive. The Ets family transcription factor, PU.1, encoded by Spi1, is essential for the development of myeloid and lymphoid cells. Our previous research illustrated the tumor suppressor function of PU.1 in classical Hodgkin lymphoma and myeloma cells. In the current study, we found that patients with DLBCL exhibited notably reduced PU.1 expression in their lymphoma cells, particularly in the non-germinal center B-cell-like (GCB) subtype. This observation suggests that downregulation of PU.1 may be implicated in DLBCL tumor growth. To further assess PU.1's role in mature B cells in vivo, we generated conditional Spi1 knockout mice using Cγ1-Cre mice. Remarkably, 13 of the 23 knockout mice (56%) showed splenomegaly, lymphadenopathy, or masses, with some having histologically confirmed B-cell lymphomas. In contrast, no wild-type mice developed B-cell lymphoma. In addition, RNA-seq analysis of lymphoma cells from Cγ1-Cre Spi1F/F mice showed high frequency of each monoclonal CDR3 sequence, indicating that these lymphoma cells were monoclonal tumor cells. When these B lymphoma cells were transplanted into immunodeficient recipient mice, all mice died within 3 weeks. Lentiviral-transduced Spi1 rescued 60% of the recipient mice, suggesting that PU.1 has a tumor suppressor function in vivo. Collectively, PU.1 is a tumor suppressor in mature B cells, and decreased PU.1 results in mature B-cell lymphoma development.

The gut microbiota is altered significantly in primary diffuse large b-cell lymphoma patients and relapse refractory diffuse large b-cell lymphoma patients

PURPOSE

Studies have shown that the gut microbiota may affect anti-tumor immunity by regulating the host immune system and tumor microenvironment. To date, little is known about whether the gut microbiota underlies the occurrence of diffuse large B-cell lymphoma (DLBCL) and drug resistance.

METHODS

In the present study, we compared the gut microbiota structure of fecal samples from 26 patients with primary DLBCL, 28 patients with relapsed and refractory (RR) DLBCL, and 30 healthy people.

RESULTS

Notably, Fusobacteria (from phylum to species) was enriched in the primary group. A decrease of Fusobacterium and an increase of Enterococcus were found in the RR group. PICRUSt analysis found that genes related to cytochrome P450 were upregulated in the RR group compared to the primary group, which likely contributes to the occurrence of DLBCL and the formation of drug resistance.

CONCLUSIONS

Our study provides further evidence for the relationship between gut microbiota and DLBCL and the formation of drug resistance, highlighting the potential significance of the bacterial variations may be used as new biomarkers of DLBCL.

Hyperactivating EZH2 to augment H3K27me3 levels in regulatory T cells enhances immune suppression by driving early effector differentiation

The immunosuppressive function of regulatory T (Treg) cells is essential for maintaining immune homeostasis. Enhancer of zeste homolog 2 (EZH2), a histone H3 lysine 27 (H3K27) methyltransferase, plays a key role in maintaining Treg cell function upon CD28 co-stimulation, and Ezh2 deletion in Treg cells causes autoimmunity. Here, we assess whether increasing H3K27me3 levels, by using an Ezh2Y641F gain-of-function mutation, will improve Treg cell function. We find that Treg cells expressing Ezh2Y641F display an effector Treg phenotype, are poised for improved homing to organ tissues, and can accelerate remission from autoimmunity. The H3K27me3 landscape and transcriptome of naive Ezh2Y641F Treg cells exhibit a redistribution of H3K27me3 modifications that recapitulates the gene expression profile of activated Ezh2WT Treg cells after CD28 co-stimulation. Altogether, increased H3K27me3 levels promote the differentiation of effector Treg cells that can better suppress autoimmunity.

Circulating tumor DNA in diffuse large B-cell lymphoma: analysis of response assessment, correlation with PET/CT and clone evolution

INTRODUCTION

Circulating tumor DNA (ctDNA) can be obtained from cell-free DNA (cfDNA) andis a new technique for genotyping, response assessment and prognosis in lymphoma.

METHODS

Eighteen patients with samples at diagnosis (ctDNA1), after treatment (ctDNA2) and extracted from diagnostic tissue (FFPE) were evaluated.

RESULTS

In all patients, at least one mutation in cfDNA was detected at diagnosis. CREBBP was the most frequent mutated gene (67 %). In 12 of the 15 patients with complete remission, the mutation attributed to the disease found at diagnosis cleared with treatment. A reduction in the ctDNA was observed after treatment in 14 patients, 12 of whom achieved complete remission. Correlations were found between the ctDNA at diagnosis and total metabolic tumor volume (r = 0.51; p-value = 0.014) and total lesion glycolysis 2.5 (r = 0.47; p-value = 0.024) by PET at diagnosis and between ctDNA at diagnosis and radiomic features of the lesions with the largest standardized uptake value. There was a strong inverse correlation between ΔctDNA1 and ΔSUVmax by PET/CT (r = -0.8788; p-value = 0.002).

CONCLUSION

Analysis of ctDNA and PET/CT in large B-cell lymphoma are complementary data for evaluating tumor burden and tumor clearance after treatment. Analysis of radiomic data might help to identify tumor characteristics and their changes after treatment.

Imatinib mesylate reduces c-MYC expression in double-hit lymphoma cells by suppressing inducible cytidine deaminase

BACKGROUND

Double-hit lymphoma (DHL) with c-MYC gene translocation is highly aggressive and has a poor prognosis. In DHL cells, activation-induced cytidine deaminase (AID) promotes antibody class switch recombination (CSR), ultimately leading to c-MYC gene translocation caused by Myc/IgH DNA double-strand breaks. However, currently there is still no method to suppress the expression of AID.

METHODS

In this study, we compared the clinical significance of AID expression in DHL, Additionally, two human double-hit lymphoma cell lines were used to analyze the effect of imatinib mesylate on c-MYC in vitro, and the therapeutic effect was also evaluated in xenograft mouse models.

RESULTS

Imatinib mesylate downregulated the AID and c-MYC proteins in patients with chronic myelogenous leukemia associated with DHL. In addition, imatinib mesylate reduced AID and c-MYC expression in SU-DHL-4 and OCI-Ly18 DHL cells. Imatinib mesylate exerted significant inhibitory effects on the proliferation and metastasis of SU-DHL-4 and OCI-Ly18 cells. Finally, imatinib mesylate reduced not only tumor burden in DHL mouse models, but also AID and c-MYC expression in vivo.

CONCLUSION

These findings reveal that imatinib mesylate effectively reduces the carcinogenic function of c-MYC in DHL, providing novel strategies for developing therapies targeting c-MYC-driven DHL.

EQ-5D-5L and SF-6Dv2 health utilities scores of diffuse large B-cell lymphoma patients in China

BACKGROUND

This study evaluates the health-related quality of life (HRQoL) of persons with diffuse large B-cell lymphoma (DLBCL) by using EQ-5D-5L and SF-6Dv2 and compares the measurement properties of the two instruments.

METHOD

DLBCL patients were identified via a patient group and were surveyed using web-based questionnaires. Demographic information, socioeconomic status (SES), clinical characteristics, and EQ-5D-5L and SF-6Dv2 responses were collected and statistically described. The association between the EQ-5D-5L and SF-6Dv2 dimensions were analyzed using the Spearman's correlation coefficient, whereas the correlation of the utility scores was evaluated using Pearson's correlation coefficient. The agreement between the responses of the two instruments were examined using a Bland-Altman (B-A) plot. A one-way analysis of variance (ANOVA) was performed to compare the utility scores across subgroups in different clinical states (a t-test was used if there were two subgroups). In addition, the graded response model (GRM) was used to describe the discrimination ability and difficulty characteristics of the dimensions in the two instruments.

RESULTS

In total, 582 valid responses were collected, among which 477 respondents were associated with initial-treatment and 105 respondents were relapsed/refractory (RR) patients. The mean (standard deviation [SD]) EQ-5D-5L and SF-6Dv2 utility scores of the DLBCL patients were 0.828 (0.222) and 0.641 (0.220), respectively. The correlation between the EQ-5D-5L and SF-6Dv2 dimensions ranged from 0.299 to 0.680, and the correlation between their utility scores was 0.787. The B-A plot demonstrated an acceptable but not strong agreement between EQ-5D-5L and SF-6Dv2 utility scores. The GRM model results indicated that all dimensions of each instrument were highly discriminating overall, but EQ-5D-5L had suboptimal discriminative power among patients with good health.

CONCLUSION

Both the EQ-5D-5L and SF-6Dv2 showed valid properties to assess the HRQoL of DLBCL patients. However, utility scores derived from the two instruments had substantial difference, thereby prohibiting the interchangeable use of utilities from the two instruments.

Epstein-Barr virus-positive, primary cutaneous marginal zone lymphoma, with transformation: Case report and review of the literature

Epstein-Barr Virus (EBV) positive primary cutaneous marginal zone lymphoma (PCMZL) is uncommon and subsequent transformation is rare.

METHODS

We report a patient with EBV positive PCMZL with subsequent transformation to plasmablastic lymphoma and review the literature for transformed PCMZL to assess clinical and pathologic characteristics. In the case we describe, the patient presented with multifocal PCMZL, developed large B cell transformation with plasmacytic differentiation, followed by plasmablastic transformation (PBL), and ultimately died of disease progression despite multiple lines of therapy. Past history was significant for psoriatic arthritis (multiple prior lines of immunomodulatory therapy). The lymphomas and non-involved bone marrow share the same somatic DNMT3A and TET2 mutations, suggesting clonal relatedness and an association with clonal hematopoiesis (CH).

RESULTS

Eighteen cases complied the cohort (seventeen cases from the literature and the case reported herein). Nearly half of the eighteen cases of PCMZL with transformation died of progressive disease (44%). Transformed cases were more commonly seen in patients with >2 sites at initial diagnosis. EBV was assessed in 5 patients, 3 were positive (all died of disease). Two patients with NGS studies demonstrated TET2 and DNMT3A mutations.

CONCLUSIONS

Transformation of EBV positive PCMZL appears to be a poor prognostic indicator, with our reported case being the first well defined case transformed to PBL, suspected to arise from myeloid-CH.

Characterizing the Cell-Free Transcriptome in a Humanized Diffuse Large B-Cell Lymphoma Patient-Derived Tumor Xenograft Model for RNA-Based Liquid Biopsy in a Preclinical Setting

The potential of RNA-based liquid biopsy is increasingly being recognized in diffuse large B-cell lymphoma (DLBCL), the most common subtype of non-Hodgkin's lymphoma. This study explores the cell-free transcriptome in a humanized DLBCL patient-derived tumor xenograft (PDTX) model. Blood plasma samples (n = 171) derived from a DLBCL PDTX model, including 27 humanized (HIS) PDTX, 8 HIS non-PDTX, and 21 non-HIS PDTX non-obese diabetic (NOD)-scid IL2Rgnull (NSG) mice were collected during humanization, xenografting, treatment, and sacrifice. The mice were treated with either rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), CD20-targeted human IFNα2-based AcTaferon combined with CHOP (huCD20-Fc-AFN-CHOP), or phosphate-buffered saline (PBS). RNA was extracted using the miRNeasy serum/plasma kit and sequenced on the NovaSeq 6000 platform. RNA sequencing data of the formalin-fixed paraffin-embedded (FFPE) tissue and blood plasma samples of the original patient were included. Flow cytometry was performed on immune cells isolated from whole blood, spleen, and bone marrow. Bulk deconvolution was performed using the Tabula Sapiens v1 basis matrix. Both R-CHOP and huCD20-Fc-AFN-CHOP were able to control tumor growth in most mice. Xenograft tumor volume was strongly associated with circulating tumor RNA (ctRNA) concentration (p < 0.001, R = 0.89), as well as with the number of detected human genes (p < 0.001, R = 0.79). Abundance analysis identified tumor-specific biomarkers that were dynamically tracked during tumor growth or treatment. An 8-gene signature demonstrated high accuracy for assessing therapy response (AUC 0.92). The tumoral gene detectability in the ctRNA of the PDTX-derived plasma was associated with RNA abundance levels in the patient's tumor tissue and blood plasma (p < 0.001), confirming that tumoral gene abundance contributes to the cell-free RNA (cfRNA) profile. Decomposing the transcriptome, however, revealed high inter- and intra-mouse variability, which was lower in the HIS PDTX mice, indicating an impact of human engraftment on the stability and profile of cfRNA. Immunochemotherapy resulted in B cell depletion, and tumor clearance was reflected by a decrease in the fraction of human CD45+ cells. Lastly, bulk deconvolution provided complementary biological insights into the composition of the tumor and circulating immune system. In conclusion, the blood plasma-derived transcriptome serves as a biomarker source in a preclinical PDTX model, enables the assessment of biological pathways, and enhances the understanding of cfRNA dynamics.

Clinical diagnostic model for predicting indolent or aggressive lymphoma based on clinical information and ultrasound features of superficial lymph nodes

PURPOSE

The aim of this study was to develop a diagnostic model for predicting indolent lymphoma or aggressive lymphoma using clinical information and ultrasound characteristics of superficial lymph nodes.

METHOD

Patients with confirmed pathological lymphoma subtypes who had undergone ultrasound and contrast-enhanced ultrasound examinations were enrolled. Clinical and ultrasound imaging features were retrospectively analysed and compared to the pathological results, which were considered the gold standard for diagnosis. Two diagnostic models were developed: a clinical model (Model-C) using clinical data only, and a combined model (Model-US) integrating ultrasound features into the clinical model. The efficacy of these models in differentiating between indolent and aggressive lymphoma was compared.

RESULTS

In total, 236 consecutive patients were enrolled, including 78 patients with indolent lymphomas and 158 patients with aggressive lymphomas. Receiver operating characteristic (ROC) curve analysis revealed that the areas under the curves of Model-C and Model-US were 0.78 (95 % confidence interval: 0.72-0.84) and 0.87 (95 % confidence interval: 0.82-0.92), respectively (p < 0.001). Model-US was further evaluated for calibration and is presented as a nomogram.

CONCLUSIONS

The diagnostic model incorporated clinical and ultrasound characteristics and offered a noninvasive method for assessing lymphoma with good discrimination and calibration.

Wogonin induces mitochondrial apoptosis and synergizes with venetoclax in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is among the most aggressive hematological malignancies and patients are commonly treated with combinatorial immunochemotherapies such as R-CHOP. Till now, the prognoses are still variable and unsatisfactory, depending on the molecular subtype and the treatment response. Developing effective and tolerable new agents is always urgently needed, and compounds from a natural source have gained increasing attentions. Wogonin is an active flavonoid extracted from the traditional Chinese herbal medicine Scutellaria baicalensis Georgi and has shown extensive antitumor potentials. However, the therapeutic effect of wogonin on DLBCL remains unknown. Here, we found that treatment with wogonin dose- and time-dependently reduced the viability in a panel of established DLBCL cell lines. The cytotoxicity of wogonin was mediated through apoptosis induction, along with the loss of mitochondrial membrane potential and the downregulation of BCL-2, MCL-1, and BCL-xL. In terms of the mechanism, wogonin inhibited the PI3K and MAPK pathways, as evidenced by the clear decline in the phosphorylation of AKT, GSK3β, S6, ERK, and P38. Furthermore, the combination of wogonin and the BCL-2 inhibitor venetoclax elicited synergistically enhanced killing effect on DLBCL cells regardless of their molecular subtypes. Finally, administration of wogonin significantly impeded the progression of the DLBCL tumor in a xenograft animal model without obvious side effects. Taken together, the present study suggests a promising potential of wogonin in the treatment of DLBCL patients either as monotherapy or an adjuvant for venetoclax-based combinations.

A new digital droplet PCR method for looking at epigenetics in diffuse large B-cell lymphomas: The role of BMI1, EZH2, and USP22 genes

INTRODUCTION

Epigenetics has been shown to be relevant in oncology: BMI1 overexpression has been reported in leukemias, EZH2 mutations have been found in follicular lymphoma, and USP22 seems to stabilize BMI1 protein. In this study, we measured the expression of BMI1, EZH2, and USP22 in lymph nodes from 56 diffuse large B-cell lymphoma (DLBCL) patients.

METHODS

A new multiplex digital droplet PCR (ddPCR) has been set up to measure the expression of 4 genes (BMI1, EZH2, USP22, and GAPDH) in the same reaction on RNA extracted from paraffin-embedded tissues.

RESULTS

The specificity of ddPCR was confirmed by a 100% alignment on the BLAST platform and its repeatability demonstrated by duplicates. A strict correlation between expression of BMI1 and EZH2 and BMI1 and USP22 has been found, and high expression of these genes was correlated with extra-nodal lymphomas. Progression-free survival (PFS) and overall survival (OS) were conditioned by IPI, bone marrow infiltration, and the complete response achievement. High levels of BMI1 and USP22 did not condition the response to therapy, but impaired the PFS, especially for patients defined at "high risk" based on the cell of origin (no germinal center [GCB]), high BCL2 expression, and IPI 3-5. In this subgroup, the probability of relapse/progression was twice higher than that of patients carrying low BMI1 and USP22 levels.

CONCLUSION

High expression of BMI1 and of USP22 might be a poor prognostic factor in DLBCL, and might represent the target for novel inhibitors.

Analysis of Histologic, Immunohistochemical and Genomic Features of Large B Cell Lymphoma Tumors May Predict Response to Polatuzumab Vedotin Based Therapy in Patients With Relapsed/Refractory Disease

BACKGROUND

Large B cell lymphoma (LBCL) is the most common form of lymphoma. Polatuzumab vedotin (polatuzumab) is an effective therapy for patients diagnosed with LBCL; however, only limited information regarding pathologic features detected by clinical laboratory assays is available to determine which patients are most likely to benefit from polatuzumab based therapies.

PATIENTS AND METHODS

We collected data from real world patients with relapsed or refractory LBCL whose tumors underwent next generation sequencing and were treated with polatuzumab based therapy at a single large academic cancer center. Tumor and patient characteristics were analyzed to look for factors that predict response to polatuzumab based therapies.

RESULTS

We identified high grade B cell lymphoma (HGBL) -NOS or MYC/BCL2 histology and presence of MYC rearrangement as factors that predict inferior response to polatuzumab based therapy. Patients with germinal center B cell of origin (GCB COO) LBCL without these factors had a high response rate (73%) to polatuzumab based therapy.

CONCLUSION

In a single center real world retrospective analysis of R/R LBCL patients with available genomic data, polatuzumab based therapy may be less effective in patients with HGBL-NOS or MYC/BCL2 histology and MYC rearrangements, but not in patients with GCB COO LBCL without these features. Routine performance of more comprehensive pathologic analysis of tumors may inform the use of polatuzumab based therapy in patients with LBCL.

Molecular Determinants of Sensitivity to Polatuzumab Vedotin in Diffuse Large B-Cell Lymphoma

Polatuzumab vedotin (Pola-V) is an antibody-drug conjugate directed to the CD79B subunit of the B-cell receptor (BCR). When combined with conventional immunochemotherapy, Pola-V improves outcomes in diffuse large B-cell lymphoma (DLBCL). To identify determinants of Pola-V sensitivity, we used CRISPR-Cas9 screening for genes that modulated Pola-V toxicity for lymphomas or the surface expression of its target, CD79B. Our results reveal the striking impact of CD79B glycosylation on Pola-V epitope availability on the lymphoma cell surface and on Pola-V toxicity. Genetic, pharmacological, and enzymatic approaches that remove sialic acid from N-linked glycans enhanced lymphoma killing by Pola-V. Pola-V toxicity was also modulated by KLHL6, an E3 ubiquitin ligase that is recurrently inactivated in germinal center derived lymphomas. We reveal how KLHL6 targets CD79B for degradation in normal and malignant germinal center B cells, thereby determining expression of the surface BCR complex. Our findings suggest precision medicine strategies to optimize Pola-V as a lymphoma therapeutic. Significance: These findings unravel the molecular basis of response heterogeneity to Pola-V and identify approaches that might be deployed therapeutically to enhance the efficacy of CD79B-specific tumor killing. In addition, they reveal a novel post-translational mechanism used by normal and malignant germinal center B cells to regulate expression of the BCR. See related commentary by Leveille, p. 1577 See related article by Meriranta et al.

Ibrutinib in Combination with R-GemOx in Patients with Relapsed or Refractory Diffuse Large B-cell Lymphoma of Nongerminal Center B-cell-like Type: Phase II Clinical Trial of the Spanish GELTAMO Group

PURPOSE

This phase II clinical trial evaluated the combination of ibrutinib with rituximab, gemcitabine, and oxaliplatin (R-GemOx) in patients with nongerminal center B-cell-like (non-GCB) diffuse large B-cell lymphoma (DLBCL).

PATIENTS AND METHODS

The IBDCL trial (NCT02692248) included patients with histologic diagnosis of non-GCB DLBCL with relapsed or refractory disease and non-candidates for stem-cell transplantation. Patients received an induction treatment consisting of six or eight cycles of R-GemOx at standard doses every 2 weeks, in combination with ibrutinib (560 mg daily), followed by a maintenance treatment with ibrutinib for a maximum of 2 years. The primary objective was to evaluate the overall response rate after four cycles.

RESULTS

Sixty-four patients were included, 72% of them refractory to the last regimen. The overall response rate and complete remission rate after the fourth cycle were 53% [95% confidence interval (CI), 41-65] and 34% (95% CI, 24-46), respectively. Twenty-four (37%) patients started maintenance, and 7 (11%) completed the planned 2 years. After a median follow-up of 29.7 months (range: 0.4-48.6), the estimated 2-year progression-free survival and overall survival were 18% (95% CI, 8-28) and 26% (95% CI, 14-37), respectively. The most common grade ≥3 treatment-related adverse events were thrombocytopenia (44%), neutropenia (30%), and anemia (14%). Grade ≥3 infectious and cardiovascular treatment-related adverse events were reported in 6 (9%) and 1 (2%) patient, respectively.

CONCLUSIONS

Ibrutinib in combination with R-GemOx, followed by ibrutinib maintenance, demonstrated encouraging antitumor activity with durable responses and a manageable toxicity in patients with non-GCB DLBCL.

Disruption of KLHL6 Fuels Oncogenic Antigen Receptor Signaling in B-Cell Lymphoma

Pathomechanisms that activate oncogenic B-cell receptor (BCR) signaling in diffuse large B-cell lymphoma (DLBCL) are largely unknown. Kelch-like family member 6 (KLHL6) encoding a substrate-adapter for Cullin-3-RING E3 ubiquitin ligase with poorly established targets is recurrently mutated in DLBCL. By applying high-throughput protein interactome screens and functional characterization, we discovered that KLHL6 regulates BCR by targeting its signaling subunits CD79A and CD79B. Loss of physiologic KLHL6 expression pattern was frequent among the MCD/C5-like activated B-cell DLBCLs and was associated with higher CD79B levels and dismal outcome. Mutations in the bric-a-brac tramtrack broad domain of KLHL6 disrupted its localization and heterodimerization and increased surface BCR levels and signaling, whereas Kelch domain mutants had the opposite effect. Malfunctions of KLHL6 mutants extended beyond proximal BCR signaling with distinct phenotypes from KLHL6 silencing. Collectively, our findings uncover how recurrent mutations in KLHL6 alter BCR signaling and induce actionable phenotypic characteristics in DLBCL. Significance: Oncogenic BCR signaling sustains DLBCL cells. We discovered that Cullin-3-RING E3 ubiquitin ligase substrate-adapter KLHL6 targets BCR heterodimer (CD79A/CD79B) for ubiquitin-mediated degradation. Recurrent somatic mutations in the KLHL6 gene cause corrupt BCR signaling by disrupting surface BCR homeostasis. Loss of KLHL6 expression and mutant-induced phenotypes associate with targetable disease characteristics in B-cell lymphoma. See related commentary by Leveille et al. See related commentary by Corcoran et al.

Advances in biology, diagnosis and treatment of DLBCL

Diffuse large B-cell lymphoma (DLBCL), with approximately 150,000 new cases worldwide each year, represent nearly 30% of all cases of non-Hodgkin lymphoma (NHL) and are phenotypically and genetically heterogeneous. A gene-expression profile (GEP) has identified at least three major subtypes of DLBCL, each of which has distinct clinical, biological, and genetic features: activated B-cell (ABC)-like DLBCL, germinal-center B-cell (GCB)-like DLBCL, and unclassified. Different origins are associated with different responses to chemotherapy and targeted agents. Despite DLBCL being a highly heterogeneous disease, more than 60% of patients with DLBCL can be cured after using rituximab combined with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) to inhibit the growth of cancer cells while targeting the CD20 receptor. In recent decades, the improvement of diagnostic levels has led to a refinement classification of DLBCL and the development of new therapeutic approaches. The objective of this review was to summarize the latest studies examining genetic lesions and therapies for DLBCL.

Systemic diffuse large B-cell lymphoma involving the central nervous system has high rates of defective antigen presentation and immune surveillance

Not available.

Not all central nervous system lymphomas are created equal

Not available.

Spontaneous regression of primary cutaneous diffuse large B-cell lymphoma, leg type: A case series and review of the literature

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL, LT) is a subtype of cutaneous B-cell lymphoma with unfavorable prognosis usually requiring aggressive polychemotherapy for disease control. Only single cases of spontaneous regression of PCDLBCL, LT are reported in the literature, peaking 3 months post-biopsy following a clinical history of no longer than 1 year. Here, we report the first case of a spontaneously relapsing and remitting PCDLBCL, LT with complete regression after a clinical history of more than 9 years and thus an atypically indolent clinical course. The female patient presented with recurrent erythematous, non-ulcerated, non-raised plaques of the right lower leg for 6 years. Pathological workup and exclusion of a systemic disease confirmed the diagnosis of PCDLBCL, LT. Due to the history of repeated spontaneous remission, no therapy was initiated. Nine years after first occurrence the patient presented with complete clinical remission lasting for 64 months. We retrospectively identified four additional PCDLBCL, LT patients with spontaneous remission lasting up to 53 months. Our data provide evidence for a distinct PCDLBCL, LT patient subgroup that clinicians should be aware of and warrants a watch-and-wait treatment regime.

Gα13 restricts nutrient driven proliferation in mucosal germinal centers

Germinal centers (GCs) that form in mucosal sites are exposed to gut-derived factors that have the potential to influence homeostasis independent of antigen receptor-driven selective processes. The G-protein Gα13 confines B cells to the GC and limits the development of GC-derived lymphoma. We discovered that Gα13-deficiency fuels the GC reaction via increased mTORC1 signaling and Myc protein expression specifically in the mesenteric lymph node (mLN). The competitive advantage of Gα13-deficient GC B cells (GCBs) in mLN was not dependent on T cell help or gut microbiota. Instead, Gα13-deficient GCBs were selectively dependent on dietary nutrients likely due to greater access to gut lymphatics. Specifically, we found that diet-derived glutamine supported proliferation and Myc expression in Gα13-deficient GCBs in the mLN. Thus, GC confinement limits the effects of dietary glutamine on GC dynamics in mucosal tissues. Gα13 pathway mutations coopt these processes to promote the gut tropism of aggressive lymphoma.