Tumor Location Relative to the Spleen Is a Prognostic Factor in Lymphoma Patients: A Demonstration from the REMARC Trial

Baseline [18F]FDG PET/CT radiomic features can improve the survival prediction in patients with diffuse large B-cell lymphoma (DLBCL). The purpose of this study was to investigate whether characterizing tumor locations relative to the spleen location in baseline [18F]FDG PET/CT images predicts survival in patients with DLBCL and improves the predictive value of total metabolic tumor volume (TMTV) and age-adjusted international prognostic index (IPI). Methods: This retrospective study included 301 DLBCL patients from the REMARC (NCT01122472) cohort. Physicians delineated the tumor regions, whereas the spleen was automatically segmented using an open-access artificial intelligence algorithm. We systematically measured the distance between the centroid of the spleen and all other lesions, defining the SD of these distances as the lesion spread (SpreadSpleen). We calculated the maximum distance between the spleen and another lesion (Dspleen) for each patient and normalized it with the body surface area, resulting in standardized Dspleen (sDspleen). The predictive value of each PET/CT feature for progression-free survival (PFS) and overall survival (OS) was evaluated through univariate and multivariate time-dependent Cox models and Kaplan-Meier analysis. Results: In total, 282 patients (mean age, 68.33 ± 5.41 y; 164 men) were evaluated. The artificial intelligence algorithm successfully segmented the spleen in 96% of the patients. SpreadSpleen, Dspleen, and sDspleen were correlated neither with TMTV (Pearson ρ < 0.23) nor with IPI (Pearson ρ < 0.15). When median values were used as the cutoff, SpreadSpleen, Dspleen, and sDspleen all significantly classified patients into 2 risk groups for PFS and OS (P < 0.001). They complemented TMTV and IPI to classify the patients into 3 risk groups for PFS and OS (P < 0.001). Integrating SpreadSpleen, Dspleen, or sDspleen into a Cox model on the basis of TMTV, IPI, and TMTV combined with IPI significantly improved the concordance index for PFS and OS (P < 0.05). Conclusion: Baseline PET/CT features that characterize tumor spread and dissemination relative to the spleen strongly predicted survival in patients with DLBCL. Integrating these features with TMTV and IPI further improved survival prediction.

Epstein-Barr virus-encoded EBNA2 downregulates ICOSL by inducing miR-24 in B-cell lymphoma

ABSTRACT

Hematological malignancies such as Burkitt lymphoma (BL), Hodgkin lymphoma (HL), and diffuse large B-cell lymphoma (DLBCL) cause significant morbidity in humans. A substantial number of these lymphomas, particularly HL and DLBCLs have poorer prognosis because of their association with Epstein-Barr virus (EBV). Our earlier studies have shown that EBV-encoded nuclear antigen (EBNA2) upregulates programmed cell death ligand 1 in DLBCL and BLs by downregulating microRNA-34a. Here, we investigated whether EBNA2 affects the inducible costimulator (ICOS) ligand (ICOSL), a molecule required for efficient recognition of tumor cells by T cells through the engagement of ICOS on the latter. In virus-infected and EBNA2-transfected B-lymphoma cells, ICOSL expression was reduced. Our investigation of the molecular mechanisms revealed that this was due to an increase in microRNA-24 (miR-24) by EBNA2. By using ICOSL 3' untranslated region-luciferase reporter system, we validated that ICOSL is an authentic miR-24 target. Transfection of anti-miR-24 molecules in EBNA2-expressing lymphoma cells reconstituted ICOSL expression and increased tumor immunogenicity in mixed lymphocyte reactions. Because miR-24 is known to target c-MYC, an oncoprotein positively regulated by EBNA2, we analyzed its expression in anti-miR-24 transfected lymphoma cells. Indeed, the reduction of miR-24 in EBNA2-expressing DLBCL further elevated c-MYC and increased apoptosis. Consistent with the in vitro data, EBNA2-positive DLBCL biopsies expressed low ICOSL and high miR-24. We suggest that EBV evades host immune responses through EBNA2 by inducing miR-24 to reduce ICOSL expression, and for simultaneous rheostatic maintenance of proproliferative c-MYC levels. Overall, these data identify miR-24 as a potential therapeutically relevant target in EBV-associated lymphomas.

Targeted Polymersome Delivery of a Stapled Peptide for Drugging the Tumor Protein p53:BCL-2-Family Axis in Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) remains a formidable diagnosis in need of new treatment paradigms. In this work, we elucidated an opportunity for therapeutic synergy in DLBCL by reactivating tumor protein p53 with a stapled peptide, ATSP-7041, thereby priming cells for apoptosis and enhancing their sensitivity to BCL-2 family modulation with a BH3-mimetic, ABT-263 (navitoclax). While this combination was highly effective at activating apoptosis in DLBCL in vitro, it was highly toxic in vivo, resulting in a prohibitively narrow therapeutic window. We, therefore, developed a targeted nanomedicine delivery platform to maintain the therapeutic potency of this combination while minimizing its toxicity via packaging and targeted delivery of a stapled peptide. We developed a CD19-targeted polymersome using block copolymers of poly(ethylene glycol) disulfide linked to poly(propylene sulfide) (PEG-SS-PPS) for ATSP-7041 delivery into DLBCL cells. Intracellular delivery was optimized in vitro and validated in vivo by using an aggressive human DLBCL xenograft model. Targeted delivery of ATSP-7041 unlocked the ability to systemically cotreat with ABT-263, resulting in delayed tumor growth, prolonged survival, and no overt toxicity. This work demonstrates a proof-of-concept for antigen-specific targeting of polymersome nanomedicines, targeted delivery of a stapled peptide in vivo, and synergistic dual intrinsic apoptotic therapy against DLBCL via direct p53 reactivation and BCL-2 family modulation.

[18F-FDG PET/CT Metabolic Parameters and Circulating Tumour DNA Mutation Abundance in Diffuse Large B-Cell Lymphoma: Correlation and Survival Analysis]

OBJECTIVE

To investigate the correlation between 18Fluoro-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) metabolic parameters and peripheral blood circulating tumour DNA (ctDNA) in patients with diffuse large B-cell lymphoma (DLBCL), and the prognostic value of these two types of parameters in predicting progression-free survival (PFS).

METHODS

Clinical, PET/CT and ctDNA data of DLBCL patients who underwent peripheral blood ctDNA testing and corresponding PET/CT scans during the same period were retrospectively analyzed. At the time of ctDNA sampling and PET scan, patients were divided into baseline and relapsed/refractory (R/R) groups according to different disease conditions. CtDNA mutation abundance was expressed as variant allele frequency (VAF), including maximum VAF (maxVAF) and mean VAF (meanVAF). Total metabolic tumour volume (TMTV) and total lesion glycolysis (TLG) were obtained by the 41% maximum normalized uptake value method, and the distance between the two farthest lesions (Dmax) was used to assess the correlation between PET parameters and ctDNA mutation abundance using Spearman correlation analysis. The receiver operating characteristic (ROC) curves were used to obtain the optical cut-off values of those parameters in predicting PFS in the baseline and R/R groups, respectively. Survival curves were outlined using the Kaplan-Meier method and log-rank test was performed to compare survival differences.

RESULTS

A total of 67 DLBCL patients ［28 males and 39 females, median age 56.0(46.0, 67.0) years］ were included and divided into baseline group (29 cases) and R/R group (38 cases). Among these PET parameters, baseline TMTV, TLG, and Dmax were significantly correlated with baseline ctDNA mutation abundance, except for maximum standardized uptake value (SUVmax) (maxVAF vs TMTV: r=0.711; maxVAF vs TLG: r=0.709; maxVAF vs Dmax: r=0.672; meanVAF vs TMTV: r=0.682; meanVAF vs TLG: r=0.677; meanVAF vs Dmax: r=0.646). While in all patients, these correlations became weaker significantly. Among R/R patients, only TMTV had a weak correlation with meanVAF (r=0.376). ROC analysis showed that, the specificity of TMTV, TLG and Dmax in predicting PFS was better than mutation abundance, while the sensitivity of ctDNA mutation abundance was better. Except R/R patients, TMTV, TLG, Dmax, and VAF were significantly different at normal/elevated lactate dehydrogenase in baseline group and all patients (all P<0.05). Survival curves indicated that high TMTV (>109.5 cm3), high TLG (>2 141.3), high Dmax (>33.1 cm) and high VAF (maxVAF>7.74%, meanVAF>4.39%) were risk factors for poor PFS in baseline patients, while only high VAF in R/R patients (both maxVAF and meanVAF >0.61%) was a risk factor for PFS.

CONCLUSION

PET-derived parameters correlate well with ctDNA mutation abundance, especially in baseline patients. VAF of ctDNA predicts PFS more sensitively than PET metabolic parameters, while PET metabolic tumour burden with better specificity. TMTV, TLG and VAF all have good prognostic value for PFS. PET/CT combined with ctDNA has potential for further studies in prognostic assessment and personalized treatment.

Leukemic presentation and progressive genomic alterations of MCD/C5 diffuse large B-cell lymphoma (DLBCL)

Diffuse large B-cell lymphoma (DLBCL) is a heterogenous group of lymphoid malignancies. Based on gene expression profiling, it has been subdivided into germinal center (GC)-derived and activated B-cell (ABC) types. Advances in molecular methodologies have further refined the subclassification of DLBCL, based on recurrent genetic abnormalities. Here, we describe a distinct case of DLBCL that presented in leukemic form. DNA sequencing targeting 275 genes revealed pathogenically relevant mutations of CD79B, MyD88, TP53, TBL1XR1, and PIM1 genes, indicating that this lymphoma would be best classified as MCD/C5 DLBCL, an ABC subtype. Despite an initial good clinical response to BTK inhibitor ibrutinib, anti-CD20 antibody rituxan, alkylating agent bendamustine, and hematopoietic stem-cell transplant, the lymphoma relapsed, accompanied by morphologic and molecular evidence of disease progression. Specifically, the recurrent tumor developed loss of TP53 heterozygosity (LOH) and additional chromosomal changes central to ABC DLBCL pathogenesis, such as PRDM1 loss. Acquired resistance to ibrutinib and rituxan was indicated by the emergence of BTK and FOXO1 mutations, respectively, as well as apparent activation of alternative cell-activation pathways, through copy-number alterations (CNAs), detected by high-resolution chromosomal microarrays. In vitro, studies of relapsed lymphoma cells confirmed resistance to standard BTK inhibitors but sensitivity to vecabrutinib, a noncovalent inhibitor active against both wild-type as well as mutated BTK. In summary, we provide in-depth molecular characterization of a de novo leukemic DLBCL and discuss mechanisms that may have contributed to the lymphoma establishment, progression, and development of drug resistance.

CARD11 gain of function upregulates BCL2A1 expression and promotes resistance to targeted therapies combination in B-cell lymphoma

A strategy combining targeted therapies is effective in B-cell lymphomas (BCL), such as mantle cell lymphoma (MCL), but acquired resistances remain a recurrent issue. In this study, we performed integrative longitudinal genomic and single-cell RNA-sequencing analyses of patients with MCL who were treated with targeted therapies against CD20, BCL2, and Bruton tyrosine kinase (OAsIs trial). We revealed the emergence of subclones with a selective advantage against OAsIs combination in vivo and showed that resistant cells were characterized by B-cell receptor (BCR)-independent overexpression of NF-κB1 target genes, especially owing to CARD11 mutations. Functional studies demonstrated that CARD11 gain of function not only resulted in BCR independence but also directly increased the transcription of the antiapoptotic BCL2A1, leading to resistance against venetoclax and OAsIs combination. Based on the transcriptional profile of OAsIs-resistant subclones, we designed a 16-gene resistance signature that was also predictive for patients with MCL who were treated with conventional chemotherapy, underlying a common escape mechanism. Among druggable strategies to inhibit CARD11-dependent NF-κB1 transduction, we evaluated the selective inhibition of its essential partner MALT1. We demonstrated that MALT1 protease inhibition led to a reduction in the expression of genes involved in OAsIs resistance, including BCL2A1. Consequently, MALT1 inhibition induced synergistic cell death in combination with BCL2 inhibition, irrespective of CARD11 mutational status, both in vitro and in vivo. Taken together, our study identified mechanisms of resistance to targeted therapies and provided a novel strategy to overcome resistance in aggressive BCL. The OAsIs trial was registered at www.clinicaltrials.gov #NCT02558816.

IL-1R8 expression in DLBCL regulates NK cell recruitment and influences patient prognosis

The precise biological function of Interleukin-1 receptor 8 (IL-1R8) in diffuse large B-cell lymphoma (DLBCL) is still not well understood. Our goal is to decipher the profile of IL-1R8 expression status in DLBCL and to explore how IL-1R8 is involved in DLBCL progression. Utilizing a tissue microarray consisting of 70 samples of DLBCL tumors alongside 15 samples of tonsillitis, our investigation revealed a parallel expression profile of IL-1R8 between the tumor tissues and tonsillitis samples (p > 0.05). Nevertheless, an intriguing association emerged, as heightened expression of IL-1R8 correlated significantly with unfavorable survival outcomes in patients with DLBCL (p < 0.05). The status of IL-1R8 expression did not directly regulate proliferation (p > 0.05) and apoptosis (p > 0.05) in DLBCL cells via CCK8 and apoptotic assays. Subsequent chemotaxis analysis indicated that natural killer (NK) cell recruitment could be suppressed by IL-1R8 signaling in DLBCL, at least partially through CXCL1 inhibition (p < 0.05). The status of IL-1R8 expression in tumor tissues exhibited a negative correlation with the density of CD57+ NK cell infiltration (p < 0.05), while it did not demonstrate a significant association with CD3+ T cells (p > 0.05), CD68+ macrophages (p > 0.05), or S-100+ dendritic cells (p > 0.05). In line with this observation, elevated levels of NK cell infiltration demonstrated a significant positive correlation with improved overall survival (OS) among patients diagnosed with DLBCL (p < 0.05). Our data suggests the immuno-regulating potential of IL-1R8 through NK cell recruitment in DLBCL, providing novel insights into future immuno-modulating therapies.

Aggressive non-Hodgkin lymphoma in the pediatric and young adult population; diagnostic and molecular pearls of wisdom

Mature non-Hodgkin lymphomas (NHLs) of the pediatric and young adults(PYA), including Burkitt lymphoma (BL), diffuse large B cell lymphoma (DLBCL), high-grade B cell lymphoma (HGBCL), primary mediastinal large B cell lymphoma (PMBL) and anaplastic large cell lymphoma (ALCL), generally have excellent prognosis compared to the adult population. BL, DLBCL and HGBCL are usually of germinal center (GCB) origin in the PYA population. PMBL neither belongs to the GCB nor the activated B cell subtype and is associated with a poorer outcome than BL or DLBCL of comparable stage. Anaplastic large cell lymphoma is the most frequent peripheral T cell lymphoma occurring in the PYA and accounts for 10-15% of childhood NHL. Most pediatric ALCL, unlike in the adult, demonstrate expression of anaplastic lymphoma kinase (ALK). In recent years, the understanding of the biology and molecular features of these aggressive lymphomas has increased tremendously. This has led to reclassification of newer PYA entities including Burkitt-like lymphoma with 11q aberration. In this review, we will discuss the current progress discovered in frequently encountered aggressive NHLs in the PYA, highlighting the clinical, pathologic and molecular features that aid in the diagnosis of these aggressive lymphomas. We will be updating the new concepts and terminologies used in the new classification systems.

TCFL5 knockdown sensitizes DLBCL to doxorubicin treatment via regulation of GPX4

BACKGROUND

Resistance to chemo-drug is a major cause of bad outcome in diffuse large B-cell lymphoma (DLBCL). It was reported that TCFL5 may be related to chemoresistance in childhood acute lymphoblastic leukemia. However, it is still unclear whether TCFL5 is involved in DLBCL drug-resistance.

METHODS

To explore the underlying mechanism of doxorubicin resistance, recombinant lentivirus was applied to control expression of TCFL5 in DLBCL cells. CCK-8 assay was perfomed to investigate the influence of doxorubicin on proliferation of TCFL5-overexpressed or sh-TCFL5 DLBCL cells. Correlation between TCFL5 and GPX4 was analyzed with bioinformatic methods, which was further confirmed by qPCR and western blot. TCFL5 overexpression conferred doxorubicin resistance via regulating GPX4 and was verified by TUNEL assay and western blot in vitro and mice model in vivo.

RESULTS

TCFL5 was enriched in DLBCL cells and conferred doxorubicin resistance through binding to GPX4. Inhibition of TCFL5 enhanced the sensitivity of DLBCL cells to doxorubicin. GPX4 knockdown reversed doxorubicin resistance in TCFL5-overexpressed DLBCL cells.

CONCLUSION

DLBCL cells overexpress TCFL5 that promotes chemoresistance by regulating GPX4. Targeting TCFL5 may provide a prospective therapeutic strategy for doxorubicin-resistant DLBCL.

Significant increase in MIC-A and MIC-B and soluble MIC-A and MIC-B in canine lymphomas

Non-Hodkin's lymphoma (NHL) is the most frequent hematologic malignancy in humans and dogs. NKG2D is one of the most critical receptors on NK cells, recognizing their natural ligands on malignant cells such as A and B major histocompatibility complex-related proteins (MIC-A and MIC-B). Soluble molecules (sMIC-A and sMIC-B) can interfere with immune synapsis between NK cells and tumor cells, impeding NK cytotoxicity. The main objectives of this study were to analyze, in dogs with diffuse large B cell lymphoma, NK cell lymphoma, and reactive lymphadenopathies, the role of NK cells, their activating receptors NKG2D and NKp46, and their ligands MIC-A and MIC-B, as well as soluble molecules sMIC-A and sMIC-B. Thirty-six dogs with a possible diagnosis of NHL and eight healthy dogs were studied. NHL was diagnosed in 28 (78 %) dogs; in the other 8 (22 %), reactive lymphadenopathies were present. Most of the lymphomas corresponded to B cell NHL (82 %). The most predominant subtype was diffuse large B cell lymphoma (21, 71.5 %), followed by five cases (18 %) that were Non-B Non-T lymphomas (presumably NK cell lymphomas) and other B cell lymphomas (3, 10.5%). There were no cases of T cell NHL. MIC-A was positive in 7 of 27 (26 %) cases of NHL, and MIC-B in 20 of 27 (74 %) NHL. In non-malignant lymphadenopathies, three (37.5 %) dogs were positive for MIC-A, and five (62.5 %) expressed MIC-B. Dogs with lymphoma had higher numbers of NK cells than eight healthy dogs. In 15 dogs (12 cases with NHL and three cases with reactive adenopathies) and eight controls, there were no differences in the number of NK cells expressing NKP46 and NKG2D. NHL dogs had higher values of sMIC-A and sMIC-B. B-cell and NK cell lymphomas correspond to 86 % and 14 % of all canine lymphomas. MIC-A, MIC-B, and sMIC-A and sMIC-B were increased in canine lymphomas.

Dysregulation of iron homeostasis by TfR-1 renders EZH2 wild type diffuse large B-cell lymphoma resistance to EZH2 inhibition

EZH2 has been regarded as an efficient target for diffuse large B-cell lymphoma (DLBCL), but the clinical benefits of EZH2 inhibitors (EZH2i) are limited. To date, only EPZ-6438 has been approved by FDA for the treatment of follicular lymphoma and epithelioid sarcoma. We have discovered a novel EZH1/2 inhibitor HH2853 with a better antitumor effect than EPZ-6438 in preclinical studies. In this study we explored the molecular mechanism underlying the primary resistance to EZH2 inhibitors and sought for combination therapy strategy to overcome it. By analyzing EPZ-6438 and HH2853 response profiling, we found that EZH2 inhibition increased intracellular iron through upregulation of transferrin receptor 1 (TfR-1), ultimately triggered resistance to EZH2i in DLBCL cells. We demonstrated that H3K27ac gain by EZH2i enhanced c-Myc transcription, which contributed to TfR-1 overexpression in insensitive U-2932 and WILL-2 cells. On the other hand, EZH2i impaired the occurrence of ferroptosis by upregulating the heat shock protein family A (Hsp70) member 5 (HSPA5) and stabilizing glutathione peroxidase 4 (GPX4), a ferroptosis suppressor; co-treatment with ferroptosis inducer erastin effectively overrode the resistance of DLBCL to EZH2i in vitro and in vivo. Altogether, this study reveals iron-dependent resistance evoked by EZH2i in DLBCL cells, and suggests that combination with ferroptosis inducer may be a promising therapeutic strategy.

BRD4 inhibition sensitizes diffuse large B-cell lymphoma cells to ferroptosis

Diffuse large B-cell lymphoma (DLBCL), the most common form of non-Hodgkin lymphoma, is characterized by an aggressive clinical course. In approximately one-third of patients with DLBCL, first-line multiagent immunochemotherapy fails to produce a durable response. Molecular heterogeneity and apoptosis resistance pose major therapeutic challenges in DLBCL treatment. To circumvent apoptosis resistance, the induction of ferroptosis might represent a promising strategy for lymphoma therapy. In this study, a compound library, targeting epigenetic modulators, was screened to identify ferroptosis-sensitizing drugs. Strikingly, bromodomain and extra-terminal domain (BET) inhibitors sensitized cells of the germinal center B-cell-like (GCB) subtype of DLBCL to ferroptosis induction and the combination of BET inhibitors with ferroptosis inducers, such as dimethyl fumarate or RSL3, synergized in the killing of DLBCL cells in vitro and in vivo. On the molecular level, the BET protein BRD4 was found to be an essential regulator of ferroptosis suppressor protein 1 expression and thus to protect GCB-DLBCL cells from ferroptosis. Collectively, we identified and characterized BRD4 as an important player in ferroptosis suppression in GCB-DLBCL and provide a rationale for the combination of BET inhibitors with ferroptosis-inducing agents as a novel therapeutic approach for DLBCL treatment.

Proteomics Identifies Circulating TIMP-1 as a Prognostic Biomarker for Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease, although disease stratification using in-depth plasma proteomics has not been performed to date. By measuring more than 1000 proteins in the plasma of 147 DLBCL patients using data-independent acquisition mass spectrometry and antibody array, DLBCL patients were classified into four proteomic subtypes (PS-I-IV). Patients with the PS-IV subtype and worst prognosis had increased levels of proteins involved in inflammation, including a high expression of metalloproteinase inhibitor-1 (TIMP-1) that was associated with poor survival across two validation cohorts (n = 180). Notably, the combination of TIMP-1 with the international prognostic index (IPI) identified 64.00% to 88.24% of relapsed and 65.00% to 80.49% of deceased patients in the discovery and two validation cohorts, which represents a 24.00% to 41.67% and 20.00% to 31.70% improvement compared to the IPI score alone, respectively. Taken together, we demonstrate that DLBCL heterogeneity is reflected in the plasma proteome and that TIMP-1, together with the IPI, could improve the prognostic stratification of patients.

BCL-W makes only minor contributions to MYC-driven lymphoma development

The BH3-mimetic drug Venetoclax, a specific inhibitor of anti-apoptotic BCL-2, has had clinical success for the treatment of chronic lymphocytic leukaemia and acute myeloid leukaemia. Attention has now shifted towards related pro-survival BCL-2 family members, hypothesising that new BH3-mimetic drugs targeting these proteins may emulate the success of Venetoclax. BH3-mimetics targeting pro-survival MCL-1 or BCL-XL have entered clinical trials, but managing on-target toxicities is challenging. While increasing evidence suggests BFL-1/A1 is a resistance factor for diverse chemotherapeutic agents and BH3-mimetic drugs in haematological malignancies, few studies have explored the role of BCL-W in the development, expansion, and therapeutic responses of cancer. Previously, we found that BCL-W was not required for the ongoing survival and growth of various established human Burkitt lymphoma and diffuse large B cell lymphoma cell lines. However, questions remained about whether BCL-W impacts lymphoma development. Here, we show that BCL-W appears dispensable for MYC-driven lymphomagenesis, and such tumours arising in the absence of BCL-W show no compensatory changes to BCL-2 family member expression, nor altered sensitivity to BH3-mimetic drugs. These results demonstrate that BCL-W does not play a major role in the development of MYC-driven lymphoma or the responses of these tumours to anti-cancer agents.

Clinical significance of plasma PD-L1+ exosomes in the management of diffuse large B cell lymphoma

PD-L1+ exosome have been reported to be a promising prognostic biomarker in various cancers. However, its clinical value in diffuse large B cell lymphoma (DLBCL) has not been defined yet. In this study, a total of 165 plasma samples from 78 patients with DLBCL undergoing standard first-line R-CHOP regimens were collected at three different time points (pretreatment, and after 3 and 6 cycles of R-CHOP) to determine the proportions of PD-L1+ exosomes by flow cytometry. We found that high pretreatment plasma PD-L1+ exosome correlated with indicators of poor clinical outcome that included high Ki-67 expression (P = 0.02), double expressor lymphoma (P = 0.005), immunohistochemical PD-L1+ tumor tissue (P = 0.006), and the baseline maximal standardized uptake values (P = 0.0003). Pretreatment plasma PD-L1+ exosome was an independent factor by multivariate analysis with logistic regression (P = 0.0301). Moreover, the pretreatment PD-L1+ exosome was a strong predictor of final treatment responses of either CR or non-CR by ROC analysis (P < 0.001). PD-L1+ exosome level declined significantly in patients who experienced CR (pretreatment vs. after 3 cycles/after 6 cycles, P < 0.05), but not in the non-CR group. Intriguingly, plasma PD-L1+ exosome after 3 cycles (AUC = 0.857; 95%CI: 0.728-0.939) might represent a more sensitive indicator than radiographic assessment after 3 cycles (AUC = 0.626; 95%CI: 0.477-0.758) for evaluating the therapeutic response of DLBCL patients (P = 0.0136). Our results suggest that plasma PD-L1+ exosomes may represent a new biomarker for the dynamic monitoring of treatment response.

An artificial intelligence method using FDG PET to predict treatment outcome in diffuse large B cell lymphoma patients

Convolutional neural networks (CNNs) may improve response prediction in diffuse large B-cell lymphoma (DLBCL). The aim of this study was to investigate the feasibility of a CNN using maximum intensity projection (MIP) images from 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) baseline scans to predict the probability of time-to-progression (TTP) within 2 years and compare it with the International Prognostic Index (IPI), i.e. a clinically used score. 296 DLBCL 18F-FDG PET/CT baseline scans collected from a prospective clinical trial (HOVON-84) were analysed. Cross-validation was performed using coronal and sagittal MIPs. An external dataset (340 DLBCL patients) was used to validate the model. Association between the probabilities, metabolic tumour volume and Dmaxbulk was assessed. Probabilities for PET scans with synthetically removed tumors were also assessed. The CNN provided a 2-year TTP prediction with an area under the curve (AUC) of 0.74, outperforming the IPI-based model (AUC = 0.68). Furthermore, high probabilities (> 0.6) of the original MIPs were considerably decreased after removing the tumours (< 0.4, generally). These findings suggest that MIP-based CNNs are able to predict treatment outcome in DLBCL.

Targeting N-linked Glycosylation for the Therapy of Aggressive Lymphomas

Diffuse large B-cell lymphoma (DLBCL) can be subdivided into the activated B-cell (ABC) and germinal center B cell-like (GCB) subtypes. Self-antigen engagement of B-cell receptors (BCR) in ABC tumors induces their clustering, thereby initiating chronic active signaling and activation of NF-κB and PI3 kinase. Constitutive BCR signaling is essential in some GCB tumors but primarily activates PI3 kinase. We devised genome-wide CRISPR-Cas9 screens to identify regulators of IRF4, a direct transcriptional target of NF-κB and an indicator of proximal BCR signaling in ABC DLBCL. Unexpectedly, inactivation of N-linked protein glycosylation by the oligosaccharyltransferase-B (OST-B) complex reduced IRF4 expression. OST-B inhibition of BCR glycosylation reduced BCR clustering and internalization while promoting its association with CD22, which attenuated PI3 kinase and NF-κB activation. By directly interfering with proximal BCR signaling, OST-B inactivation killed models of ABC and GCB DLBCL, supporting the development of selective OST-B inhibitors for the treatment of these aggressive cancers.

SIGNIFICANCE

DLBCL depends on constitutive BCR activation and signaling. There are currently no therapeutics that target the BCR directly and attenuate its pathologic signaling. Here, we unraveled a therapeutically exploitable, OST-B-dependent glycosylation pathway that drives BCR organization and proximal BCR signaling. This article is highlighted in the In This Issue feature, p. 1749.

Rewiring cancer drivers to activate apoptosis

Genes that drive the proliferation, survival, invasion and metastasis of malignant cells have been identified for many human cancers1-4. Independent studies have identified cell death pathways that eliminate cells for the good of the organism5,6. The coexistence of cell death pathways with driver mutations suggests that the cancer driver could be rewired to activate cell death using chemical inducers of proximity (CIPs). Here we describe a new class of molecules called transcriptional/epigenetic CIPs (TCIPs) that recruit the endogenous cancer driver, or a downstream transcription factor, to the promoters of cell death genes, thereby activating their expression. We focused on diffuse large B cell lymphoma, in which the transcription factor B cell lymphoma 6 (BCL6) is deregulated7. BCL6 binds to the promoters of cell death genes and epigenetically suppresses their expression8. We produced TCIPs by covalently linking small molecules that bind BCL6 to those that bind to transcriptional activators that contribute to the oncogenic program, such as BRD4. The most potent molecule, TCIP1, increases binding of BRD4 by 50% over genomic BCL6-binding sites to produce transcriptional elongation at pro-apoptotic target genes within 15 min, while reducing binding of BRD4 over enhancers by only 10%, reflecting a gain-of-function mechanism. TCIP1 kills diffuse large B cell lymphoma cell lines, including chemotherapy-resistant, TP53-mutant lines, at EC50 of 1-10 nM in 72 h and exhibits cell-specific and tissue-specific effects, capturing the combinatorial specificity inherent to transcription. The TCIP concept also has therapeutic applications in regulating the expression of genes for regenerative medicine and developmental disorders.

High BECN1 Expression Negatively Correlates with BCL2 Expression and Predicts Better Prognosis in Diffuse Large B-Cell Lymphoma: Role of Autophagy

Diffuse large B-cell lymphoma (DLBCL) is characterized by high molecular and clinical heterogeneity. Autophagy, a lysosome-driven catabolic process devoted to macromolecular turnover, is fundamental in maintaining normal hematopoietic stem cells and progenitors homeostasis, and its dysregulation plays a critical role in the initiation and progression of hematological malignancies. One main regulator of autophagy is BECLIN-1, which may interact alternatively with either BCL-2, thus allowing apoptosis, or PI3KC3, thus promoting autophagy. The altered expression of BCL2 and BECN1 correlates with lymphoma outcomes, but whether this is associated with dysregulated cross-talk between autophagy and apoptosis remains to be elucidated. Analysis of the TCGA database revealed that BCL2 and BECN1 mRNA expression were inversely correlated in DLBCL patients. In representative DLBCL cell lines exposed to doxorubicin, the cells highly expressing BCL-2 were resistant, while the ones highly expressing BECLIN-1 were sensitive, and this correlated with low and high autophagy flux, respectively. Venetoclax targeting of BCL-2 increased while the spautin-1-mediated inhibition of BECLIN-1-dependent autophagy reversed doxorubicin sensitivity in the former and in the latter, respectively. By interrogating the TCGA DLBCL dataset, we found that BCL2 and BECN1 acted as negative and positive prognostic markers for DLBCL, respectively. The differentially expressed gene analysis in the respective cohorts revealed that BCL2 positively correlated with oncogenic pathways (e.g., glucose transport, HIF1A signaling, JAK-STAT signaling, PI3K-AKT-mTOR pathway) and negatively correlated with autophagy-related transcripts, while BECN1 showed the opposite trend. Notably, patients with high BECN1 expression displayed longer survival. Our data reveal, for the first time, that the modulation of BECLIN-1-dependent autophagy influences the prognosis of DLBCL patients and provide a mechanistic explanation supporting the therapeutic use of drugs that, by stimulating autophagy, can sensitize lymphoma cells to chemotherapy.

The Prevalence of MYD88 L265P and TNFAIP3 Mutations and Their Correlations with Clinico-Hematological Profile in Egyptian Patients with Diffuse Large B Cell Lymphoma

BACKGROUND

Activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) is characterized by chronic active B-cell receptor signaling and a constitutive activation of the NF-KB pathway. MYD88 L265P mutation occurs as a driving force of NF-KB overactivity in ABC-DLBCL. Nonetheless, in cases of DLBCL, the MYD88 L265P mutation has not yet been investigated in association with the tumour necrosis factor alpha induced protein3 (TNFAIP3) mutation.

OBJECTIVE

To investigate the frequency of MYD88 and TNFAIP3 mutations in DLBCL and their association to the clinico-hematological profile.

MATERIAL AND METHODS

We used real-time polymerase chain reaction in order to search for MYD88 L265P and TNFAIP3 mutations in 100 DLBCL patients.

RESULTS

MYD88 L265P In 20% of cases, the CT heterozygous genotype was discovered.  CT heterozygous genotype was more common in ABC type, stage IV, greater IPI groups, extra-nodal infiltration, and BM infiltration. It was also linked to a shorter OS. TNFAIP3 mutation GA heterozygous genotype was detected in 18% of the patients, with ABC-DLBCL subtype accounting for 77.8%. The GA heterozygous genotype was usually related with stage IV, extranodal infiltration, and a reduced life expectancy.

CONCLUSION

MYD88 L265P and to lesser extent TNFAIP3 mutations are major mutations in ABC- DLBCL and may be predictive factors for poor OS in ABC- DLBCL patients.

Upregulation of ENKD1 disrupts cellular homeostasis to promote lymphoma development

Diffuse large B cell lymphoma (DLBCL) is a common and aggressive form of B cell lymphoma. Approximately 40% of DLBCL patients are incurable despite modern therapeutic approaches. To explore the molecular mechanisms driving the growth and progression of DLBCL, we analyzed genes with differential expression in DLBCL using the Gene Expression Profiling Interactive Analysis database. Enkurin domain-containing protein 1 (ENKD1), a centrosomal protein-encoding gene, was found to be highly expressed in DLBCL samples compared with normal samples. The phylogenetic analysis revealed that ENKD1 is evolutionarily conserved. Depletion of ENKD1 in cultured DLBCL cells induced apoptosis, suppressed cell proliferation, and blocked cell cycle progression in the G2/M phase. Moreover, ENKD1 expression positively correlates with the expression levels of a number of cellular homeostatic regulators, including Sperm-associated antigen 5, a gene encoding an important mitotic regulator. These findings thus demonstrate a critical function for ENKD1 in regulating the cellular homeostasis and suggest a potential value of targeting ENKD1 for the treatment of DLBCL.

AMG176, an MCL-1 inhibitor, is active in pre-clinical models of aggressive B-cell lymphomas

Upregulation of the anti-apoptotic protein MCL-1 has been implicated in chemotherapy resistance and poor clinical outcomes in B-cell lymphoma (BCL). We report the activity of AMG176, a direct, selective MCL-1 inhibitor, in preclinical models of BCL. A panel of cell lines representing diffuse large B-cell lymphoma (DLBCL), double-hit lymphoma (DHL) and Burkitt's lymphoma (BL) was selected. AMG176 induced apoptotic cell death in a dose- and time-dependent manner in all BCL cell lines. Baseline MCL-1 expression was not predictive of response. AMG176 exhibited impressive synergy with venetoclax and chemotherapeutic agents, less so with proteasomal inhibitors, and antagonism with anti-CD20 monoclonal antibodies. The activity of AMG176 could not be confirmed in murine models of BCL. Combination therapy targeting MCL-1 and BCL-2 may provide an alternative therapeutic approach in BCL, however optimal patient selection will remain the key to obtaining high response rates and tolerability.

Combinatorial treatment rescues tumour-microenvironment-mediated attenuation of MALT1 inhibitors in B-cell lymphomas

Activated B-cell-like diffuse large B-cell lymphomas (ABC-DLBCLs) are characterized by constitutive activation of nuclear factor κB driven by the B-cell receptor (BCR) and Toll-like receptor (TLR) pathways. However, BCR-pathway-targeted therapies have limited impact on DLBCLs. Here we used >1,100 DLBCL patient samples to determine immune and extracellular matrix cues in the lymphoid tumour microenvironment (Ly-TME) and built representative synthetic-hydrogel-based B-cell-lymphoma organoids accordingly. We demonstrate that Ly-TME cellular and biophysical factors amplify the BCR-MYD88-TLR9 multiprotein supercomplex and induce cooperative signalling pathways in ABC-DLBCL cells, which reduce the efficacy of compounds targeting the BCR pathway members Bruton tyrosine kinase and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1). Combinatorial inhibition of multiple aberrant signalling pathways induced higher antitumour efficacy in lymphoid organoids and implanted ABC-DLBCL patient tumours in vivo. Our studies define the complex crosstalk between malignant ABC-DLBCL cells and Ly-TME, and provide rational combinatorial therapies that rescue Ly-TME-mediated attenuation of treatment response to MALT1 inhibitors.

Targeting positive cofactor 4 induces autophagic cell death in MYC-expressing diffuse large B-cell lymphoma

MYC-expressing diffuse large B-cell lymphoma (DLBCL) is one of the refractory lymphomas. Currently, the pathogenesis of MYC-expressing DLBCL is still unclear, and there is a lack of effective therapy. We characterized positive cofactor 4 (PC4) as an upstream regulator of c-Myc, and PC4 is overexpressed in DLBCL and is closely related to clinical staging, prognosis, and c-Myc expression. Furthermore, our in vivo and in vitro studies revealed that PC4 knockdown can induce autophagic cell death and enhance the therapeutic effect of doxorubicin in MYC-expressing DLBCL. Inhibition of c-Myc-mediated aerobic glycolysis and activation of the AMPK/mTOR signaling pathway are responsible for the autophagic cell death induced by PC4 knockdown in MYC-expressing DLBCL. Using dual-luciferase reporter assay and electrophoretic mobility shift assay assays, we also found that PC4 exerts its oncogenic functions by directly binding to c-Myc promoters. To sum up, our study provides novel insights into the functions and mechanisms of PC4 in MYC-expressing DLBCL and suggests that PC4 may be a promising therapeutic target for MYC-expressing DLBCL.

In Silico Identification and Functional Characterization of Genetic Variations across DLBCL Cell Lines

Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin lymphoma and frequently develops through the accumulation of several genetic variations. With the advancement in high-throughput techniques, in addition to mutations and copy number variations, structural variations have gained importance for their role in genome instability leading to tumorigenesis. In this study, in order to understand the genetics of DLBCL pathogenesis, we carried out a whole-genome mutation profile analysis of eleven human cell lines from germinal-center B-cell-like (GCB-7) and activated B-cell-like (ABC-4) subtypes of DLBCL. Analysis of genetic variations including small sequence variants and large structural variations across the cell lines revealed distinct variation profiles indicating the heterogeneous nature of DLBCL and the need for novel patient stratification methods to design potential intervention strategies. Validation and prognostic significance of the variants was assessed using annotations provided for DLBCL samples in cBioPortal for Cancer Genomics. Combining genetic variations revealed new subgroups between the subtypes and associated enriched pathways, viz., PI3K-AKT signaling, cell cycle, TGF-beta signaling, and WNT signaling. Mutation landscape analysis also revealed drug-variant associations and possible effectiveness of known and novel DLBCL treatments. From the whole-genome-based mutation analysis, our findings suggest putative molecular genetics of DLBCL lymphomagenesis and potential genomics-driven precision treatments.