Diffuse large B-cell lymphoma: reduced CD20 expression is associated with an inferior survival

Involvement of microglia-expressed MS4A6A in the onset of glioblastoma

Glioblastoma multiforme (GBM) represents the deadliest form of brain tumour, characterized by its low survival rate and grim prognosis. Cytokines released from glioma-associated microglia/macrophages are involved in establishing the tumour microenvironment, thereby crucially promoting GBM progression. MS4A6A polymorphism was confirmed to be associated with neurodegenerative and polymorphism disease pathobiology, but whether it participates in the regulation of GBM and the underlying mechanisms is still not elucidated. Here, we found that MS4A6A was significantly upregulated in GBM patient samples. The results from the single-cell RNA-sequencing (scRNA-seq) database and immunostaining demonstrated the specific expression of MS4A6A in microglial cells. In vitro, microglial overexpression of MS4A6A stimulated the proliferation and migration of glioblastoma cells. Moreover, high MS4A6A mRNA expression was related to poor prognosis in GBM patients. Our study highlights the potential of MS4A6A as a promising biomarker for GBM, which may provide novel strategies for its prevention, diagnosis and treatment.

Clinical practice guidelines for molecular tumor marker, 2nd edition review part 2

In recent years, rapid advancement in gene/protein analysis technology has resulted in target molecule identification that may be useful in cancer treatment. Therefore, "Clinical Practice Guidelines for Molecular Tumor Marker, Second Edition" was published in Japan in September 2021. These guidelines were established to align the clinical usefulness of external diagnostic products with the evaluation criteria of the Pharmaceuticals and Medical Devices Agency. The guidelines were scoped for each tumor, and a clinical questionnaire was developed based on a serious clinical problem. This guideline was based on a careful review of the evidence obtained through a literature search, and recommendations were identified following the recommended grades of the Medical Information Network Distribution Services (Minds). Therefore, this guideline can be a tool for cancer treatment in clinical practice. We have already reported the review portion of "Clinical Practice Guidelines for Molecular Tumor Marker, Second Edition" as Part 1. Here, we present the English version of each part of the Clinical Practice Guidelines for Molecular Tumor Marker, Second Edition.

Ras interacting protein 1 facilitated proliferation and invasion of diffuse large B-cell lymphoma cells

A GTPase binding protein, Ras interacting protein 1 (RASIP1), has been reported with a tumor-promoting role in lung cancer cells, and its role in lymphoma remains unknown. The analysis of medical databank shows that RASIP1 is upregulated in diffuse large B-cell lymphoma (DLBCL) specimens. In this article, we demonstrated that RASIP1 is highly expressed in DLBCL cell lines, compared with primary B cells. The gain- and loss-of-function experiments were performed to investigate the effects of RASIP1 on DLBCL cells. CCK-8, flow cytometry, western blot, and transwell assays demonstrated that silence of RASIP1 inhibited proliferation, cell cycle transition, and invasion and induced significant apoptosis in DLBCL cells, and ectopic expression of RASIP1 played opposite roles. Xenograft results revealed that RASIP1 facilitated the growth of DLBCL cells in vivo. These findings suggest that RASIP1 may be required for malignancy of DLBCL cells. In addition, we also found that the expression of RASIP1 was negatively regulated by forkhead box O3 (FOXO3), which has been reported to suppress the proliferation of DLBCL cells. Our results indicate that FOXO3 is bound to the promoter sequence of RASIP1 and inhibits its transcription. The suppressive effects of FOXO3 on proliferation and invasion of DLBCL cells were neutralized by RASIP1. In conclusion, we demonstrate that FOXO3 negatively regulated RASIP1 facilitates growth and invasion of DLBCL cells, provides novel diagnostic markers and therapeutic targets for DLBCL in clinic.

Alternative splicing of its 5'-UTR limits CD20 mRNA translation and enables resistance to CD20-directed immunotherapies

Aberrant skipping of coding exons in CD19 and CD22 compromises the response to immunotherapy in B-cell malignancies. Here, we showed that the MS4A1 gene encoding human CD20 also produces several messenger RNA (mRNA) isoforms with distinct 5' untranslated regions. Four variants (V1-4) were detected using RNA sequencing (RNA-seq) at distinct stages of normal B-cell differentiation and B-lymphoid malignancies, with V1 and V3 being the most abundant. During B-cell activation and Epstein-Barr virus infection, redirection of splicing from V1 to V3 coincided with increased CD20 positivity. Similarly, in diffuse large B-cell lymphoma, only V3, but not V1, correlated with CD20 protein levels, suggesting that V1 might be translation-deficient. Indeed, the longer V1 isoform contained upstream open reading frames and a stem-loop structure, which cooperatively inhibited polysome recruitment. By modulating CD20 isoforms with splice-switching morpholino oligomers, we enhanced CD20 expression and anti-CD20 antibody rituximab-mediated cytotoxicity in a panel of B-cell lines. Furthermore, reconstitution of CD20-knockout cells with V3 mRNA led to the recovery of CD20 positivity, whereas V1-reconstituted cells had undetectable levels of CD20 protein. Surprisingly, in vitro CD20-directed chimeric antigen receptor T cells were able to kill both V3- and V1-expressing cells, but the bispecific T-cell engager mosunetuzumab was only effective against V3-expressing cells. To determine whether CD20 splicing is involved in immunotherapy resistance, we performed RNA-seq on 4 postmosunetuzumab follicular lymphoma relapses and discovered that in 2 of them, the downregulation of CD20 was accompanied by a V3-to-V1 shift. Thus, splicing-mediated mechanisms of epitope loss extend to CD20-directed immunotherapies.

Exploring the cell-free total RNA transcriptome in diffuse large B-cell lymphoma and primary mediastinal B-cell lymphoma patients as biomarker source in blood plasma liquid biopsies

Introduction

Diffuse large B-cell lymphoma (DLBCL) and primary mediastinal B-cell lymphoma (PMBCL) are aggressive histological subtypes of non-Hodgkin's lymphoma. Improved understanding of the underlying molecular pathogenesis has led to new classification and risk stratification tools, including the development of cell-free biomarkers through liquid biopsies. The goal of this study was to investigate cell-free RNA (cfRNA) biomarkers in DLBCL and PMBCL patients.

Materials and methods

Blood plasma samples (n=168) and matched diagnostic formalin-fixed paraffin-embedded (FFPE) tissue samples (n=69) of DLBCL patients, PMBCL patients and healthy controls were collected between 2016-2021. Plasma samples were collected at diagnosis, at interim evaluation, after treatment, and in case of refractory or relapsed disease. RNA was extracted from 200 µl plasma using the miRNeasy serum/plasma kit and from FFPE tissue using the miRNeasy FFPE kit. RNA was subsequently sequenced on a NovaSeq 6000 instrument using the SMARTer Stranded Total RNA-seq pico v3 library preparation kit.

Results

Higher cfRNA concentrations were demonstrated in lymphoma patients compared to healthy controls. A large number of differentially abundant genes were identified between the cell-free transcriptomes of DLBCL patients, PMBCL patients, and healthy controls. Overlap analyses with matched FFPE samples showed that blood plasma has a unique transcriptomic profile that significantly differs from that of the tumor tissue. As a good concordance between tissue-derived gene expression and the immunohistochemistry Hans algorithm for cell-of-origin (COO) classification was demonstrated in the FFPE samples, but not in the plasma samples, a 64-gene cfRNA classifier was developed that can accurately determine COO in plasma. High plasma levels of a 9-gene signature (BECN1, PRKCB, COPA, TSC22D3, MAP2K3, UQCRHL, PTMAP4, EHD1, NAP1L1 pseudogene) and a 5-gene signature (FTH1P7, PTMAP4, ATF4, FTH1P8, ARMC7) were significantly associated with inferior progression-free and overall survival in DLBCL patients, respectively, independent of the NCCN-IPI score.

Conclusion

Total RNA sequencing of blood plasma samples allows the analysis of the cell-free transcriptome in DLBCL and PMBCL patients and demonstrates its unexplored potential in identifying diagnostic, cell-of-origin, and prognostic cfRNA biomarkers.

Mosunetuzumab monotherapy is active and tolerable in patients with relapsed/refractory diffuse large B-cell lymphoma

As part of a phase 1 or 2 study, this single-arm expansion cohort established the efficacy and safety of mosunetuzumab monotherapy in patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) (received ≥2 previous lines of therapy). Intravenous mosunetuzumab was administered with cycle (C) 1 step-up dosing for cytokine release syndrome (CRS) mitigation: C1 day (D) 1: 1 mg; C1D8 2 mg; C1D15 and C2D1: 60 mg; C3 + D1: 30 mg. Hospitalization was not mandatory. Patients with complete response (CR) completed treatment after C8; those with partial response or stable disease continued treatment for a total of 17 cycles. The primary end point was CR rate (best response), assessed against a historical control CR rate (20%) by independent review facility. Eighty-eight patients (73.9% de novo DLBCL; 26.1% transformed follicular lymphoma) were enrolled; all had received previous anthracycline and anti-CD20 therapy. Overall response and CR rates were 42.0% (95% confidence interval [CI], 31.6-53.1) and 23.9% (95% CI, 15.4-34.1), respectively; CR rate did not reach statistical significance vs the historical control (P = .36). Median time to first response was 1.4 months. Median progression-free survival was 3.2 months (95% CI, 2.2-5.3). The CR rate in 26 patients who received previous chimeric antigen receptor T-cell (CAR-T) therapy was 12%. CRS was one of the most common adverse events (26.1% of patients); predominantly grade 1 to 2 and primarily in C1. Four patients (4.5%) discontinued mosunetuzumab owing to adverse events. Mosunetuzumab demonstrated notable efficacy and a manageable safety profile in patients with R/R DLBCL, including those previously treated with CAR-Ts. This trial was registered at www.clinicaltrials.gov as #NCT02500407.

Alternative splicing of its 5'-UTR limits CD20 mRNA translation and enables resistance to CD20-directed immunotherapies

Aberrant skipping of coding exons in CD19 and CD22 compromises responses to immunotherapy for B-cell malignancies. Here, we show that the MS4A1 gene encoding human CD20 also produces several mRNA isoforms with distinct 5' untranslated regions (5'-UTR). Four variants (V1-4) were detectable by RNA-seq in distinct stages of normal B-cell differentiation and B-lymphoid malignancies, with V1 and V3 being the most abundant by far. During B-cell activation and Epstein-Barr virus infection, redirection of splicing from V1 to V3 coincided with increased CD20 positivity. Similarly, in diffuse large B-cell lymphoma only V3, but not V1, correlated with CD20 protein levels, suggesting that V1 might be translation-deficient. Indeed, the longer V1 isoform was found to contain upstream open reading frames (uORFs) and a stem-loop structure, which cooperatively inhibited polysome recruitment. By modulating CD20 isoforms with splice-switching Morpholino oligomers, we enhanced CD20 expression and anti-CD20 antibody rituximab-mediated cytotoxicity in a panel of B-cell lines. Furthermore, reconstitution of CD20-knockout cells with V3 mRNA led to the recovery of CD20 positivity, while V1-reconstituted cells had undetectable levels of CD20 protein. Surprisingly, in vitro CD20-directed CAR T cells were able to kill both V3- and V1-expressing cells, but the bispecific T cell engager mosunetuzumab was only effective against V3-expressing cells. To determine whether CD20 splicing is involved in immunotherapy resistance, we performed RNA-seq on four post-mosunetuzumab follicular lymphoma relapses and discovered that in two of them downregulation of CD20 was accompanied by the V3-to-V1 shift. Thus, splicing-mediated mechanisms of epitope loss extend to CD20-directed immunotherapies.

Key Points

In normal & malignant human B cells, CD20 mRNA is alternatively spliced into four 5'-UTR isoforms, some of which are translation-deficient.The balance between translation-deficient and -competent isoforms modulates CD20 protein levels & responses to CD20-directed immunotherapies.

Explanation of Novelty

We discovered that in normal and malignant B-cells, CD20 mRNA is alternatively spliced to generate four distinct 5'-UTRs, including the longer translation-deficient V1 variant. Cells predominantly expressing V1 were still sensitive to CD20-targeting chimeric antigen receptor T-cells. However, they were resistant to the bispecific anti-CD3/CD20 antibody mosunetuzumab, and the shift to V1 were observed in CD20-negative post-mosunetuzumab relapses of follicular lymphoma.

Targeted Silencing of NRF2 by rituximab-conjugated nanoparticles increases the sensitivity of chronic lymphoblastic leukemia cells to Cyclophosphamide

BACKGROUND

Targeting influential factors in resistance to chemotherapy is one way to increase the effectiveness of chemotherapeutics. The nuclear factor erythroid 2-related factor 2 (Nrf2) pathway overexpresses in chronic lymphocytic leukemia (CLL) cells and appears to have a significant part in their survival and chemotherapy resistance. Here we produced novel nanoparticles (NPs) specific for CD20-expressing CLL cells with simultaneous anti-Nrf2 and cytotoxic properties.

METHODS

Chitosan lactate (CL) was used to produce the primary NPs which were then respectively loaded with rituximab (RTX), anti-Nrf2 Small interfering RNA (siRNAs) and Cyclophosphamide (CP) to prepare the final version of the NPs (NP-Nrf2_siRNA-CP). All interventions were done on both peripheral blood mononuclear cells (PBMCs) and bone marrow mononuclear cells (BMNCs).

RESULTS

NP-Nrf2_siRNA-CP had satisfying physicochemical properties, showed controlled anti-Nrf2 siRNA/CP release, and were efficiently transfected into CLL primary cells (both PBMCs and BMNCs). NP-Nrf2_siRNA-CP were significantly capable of cell apoptosis induction and proliferation prevention marked by respectively decreased and increased anti-apoptotic and pro-apoptotic factors. Furthermore, use of anti-Nrf2 siRNA was corresponding to elevated sensitivity of CLL cells to CP.

CONCLUSION

Our findings imply that the combination therapy of malignant CLL cells with RTX, CP and anti-Nrf2 siRNA is a novel and efficient therapeutic strategy that was capable of destroying malignant cells. Furthermore, the use of NPs as a multiple drug delivery method showed fulfilling properties; however, the need for further future studies is undeniable. Video Abstract.

Activity of tafasitamab in combination with rituximab in subtypes of aggressive lymphoma

Background

Despite recent advances in the treatment of aggressive lymphomas, a significant fraction of patients still succumbs to their disease. Thus, novel therapies are urgently needed. As the anti-CD20 antibody rituximab and the CD19-targeting antibody tafasitamab share distinct modes of actions, we investigated if dual-targeting of aggressive lymphoma B-cells by combining rituximab and tafasitamab might increase cytotoxic effects.

Methods

Antibody single and combination efficacy was determined investigating different modes of action including direct cytotoxicity, antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) in in vitro and in vivo models of aggressive B-cell lymphoma comprising diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL).

Results

Three different sensitivity profiles to antibody monotherapy or combination treatment were observed in in vitro models: while 1/11 cell lines was primarily sensitive to tafasitamab and 2/11 to rituximab, the combination resulted in enhanced cell death in 8/11 cell lines in at least one mode of action. Treatment with either antibody or the combination resulted in decreased expression of the oncogenic transcription factor MYC and inhibition of AKT signaling, which mirrored the cell line-specific sensitivities to direct cytotoxicity. At last, the combination resulted in a synergistic survival benefit in a PBMC-humanized Ramos NOD/SCID mouse model.

Conclusion

This study demonstrates that the combination of tafasitamab and rituximab improves efficacy compared to single-agent treatments in models of aggressive B-cell lymphoma in vitro and in vivo.

Endemic Burkitt lymphoma avatar mouse models for exploring inter-patient tumor variation and testing targeted therapies

Endemic Burkitt lymphoma (BL) is a childhood cancer in sub-Saharan Africa characterized by Epstein-Barr virus and malaria-associated aberrant B-cell activation and MYC chromosomal translocation. Survival rates hover at 50% after conventional chemotherapies; therefore, clinically relevant models are necessary to test additional therapies. Hence, we established five patient-derived BL tumor cell lines and corresponding NSG-BL avatar mouse models. Transcriptomics confirmed that our BL lines maintained fidelity from patient tumors to NSG-BL tumors. However, we found significant variation in tumor growth and survival among NSG-BL avatars and in Epstein-Barr virus protein expression patterns. We tested rituximab responsiveness and found one NSG-BL model exhibiting direct sensitivity, characterized by apoptotic gene expression counterbalanced by unfolded protein response and mTOR pro-survival pathways. In rituximab-unresponsive tumors, we observed an IFN-α signature confirmed by the expression of IRF7 and ISG15. Our results demonstrate significant inter-patient tumor variation and heterogeneity, and that contemporary patient-derived BL cell lines and NSG-BL avatars are feasible tools to guide new therapeutic strategies and improve outcomes for these children.

Clinical Features, Phenotypic Markers and Outcomes of Diffuse Large B-Cell Lymphoma between HIV-Infected and HIV-Uninfected Chinese Patients

Background: The effect of HIV infection on the clinicopathological characteristics of diffuse large B-cell lymphoma (DLBCL) remains debatable. Methods: Fifty-three HIV-infected and ninety-three HIV-uninfected DLBCL patients were enrolled in the retrospective study by propensity score matching for sex, age, body mass index and international prognostic index (IPI) at a ratio of 1:2. The clinicopathological characteristics were compared between the two groups. Results: HIV-infected DLBCL patients had lower white blood cell counts [×109/L; 4.4 (3.4−5.6) vs. 6.1 (4.2−8.2), p < 0.001], platelet counts (×109/L; 184.7 ± 89.3 vs. 230.0 ± 113.9, p = 0.014) and serum albumin (g/L; 37.3 ± 6.9 vs. 41.3 ± 6.2, p < 0.001) but higher incidences of central nervous system (CNS) involvement (9.4% vs. 1.1%, p = 0.014), bone marrow involvement (24.5% vs. 11.5%, p = 0.044) and Epstein−Barr viremia (61.1% vs. 26.7%, p = 0.002) than HIV-uninfected patients. In terms of histopathology, HIV-infected patients had higher positivity of Epstein−Barr virus-encoded small RNA (EBER) (41.7% vs. 6.7%, p = 0.002), but lower CD20 (90.2% vs. 98.7%, p= 0.029) and CD79a (23.1% vs. 53.7%, p < 0.001) expression. The overall response rate (ORR) at the end of chemotherapy (70.2% vs. 87.8%, p= 0.012) and 1-year overall survival (OS) (61.7% vs. 84.2%, log-rank p = 0.006) in HIV-infected patients were significantly lower than those in HIV-uninfected patients. Multivariate analysis suggested IPI ≤2.0 [adjusted odds ratio (AOR) (95% confidence interval): 5.0 (1.2−21.2), p = 0.030] was associated with ORR, hypoalbuminemia [AOR: 3.3 (1.3−9.1), p = 0.018] and CNS involvement [AOR: 3.3 (1.0−10.5), p = 0.044] were associated with reduced 1-year OS in HIV-infected patients. Conclusion: HIV-infected DLBCL patients have unique blood profiles and phenotypic markers. Low ORR and 1-year OS were observed in HIV-infected DLBCL patients in our study, even in the HAART era.

IRF8 regulates efficacy of therapeutic anti-CD20 monoclonal antibodies

Anti-CD20 monoclonal antibodies such as Rituximab, Ofatumumab, and Obinutuzumab are widely used to treat lymphomas and autoimmune diseases. They act by depleting B cells, mainly through Fc-dependent effectors functions. Some patients develop resistance to treatment but the underlying mechanisms are poorly understood. Here, we performed a genome-wide CRISPR/Cas9 screen to identify genes regulating the efficacy of anti-CD20 antibodies. We used as a model the killing of RAJI B cells by Rituximab through complement-dependent-cytotoxicity (CDC). As expected, the screen identified MS4A1, encoding CD20, the target of Rituximab. Among other identified genes, the role of Interferon Regulatory Factor 8 (IRF8) was validated in two B-cell lines. IRF8 KO also decreased the efficacy of antibody-dependent cellular cytotoxicity and phagocytosis (ADCC and ADCP) induced by anti-CD20 antibodies. We further show that IRF8 is necessary for efficient CD20 transcription. Levels of IRF8 and CD20 RNA or proteins correlated in normal B cells and in hundreds of malignant B cells. Therefore, IRF8 regulates CD20 expression and controls the depleting capacity of anti-CD20 antibodies. Our results bring novel insights into the pathways underlying resistance to CD20-targeting immunotherapies.

A Promising Future for Precision Epigenetic Therapy for Follicular and Diffuse Large B-Cell Lymphoma?

Epigenetic mechanisms such as DNA hypermethylation or histone deacetylation normally silence gene expression that regulates numerous cellular activities. Germinal center–derived lymphomas such as follicular lymphoma (FL) and diffuse large B cell lymphoma (DLBCL) are characterized by frequent mutations of histone-modifying genes. EZH2 is essential to the formation of germinal center in the secondary lymphoid tissue (eg, lymph nodes and spleen) and is one of the most frequently mutated histone-modifying genes in human lymphomas. EZH2 encodes a histone methyltransferase, mediates transcriptional repression and acts as an oncogene that promotes the development and progression of a variety of human malignancies, including FL and DLBCL. Thus, recurrent mutations in the EZH2 and other non-histone epigenetic regulators represent important targets for therapeutic interventions. Recently, an orally active inhibitor of EZH2, tazemetostat, has received regulatory approval for patients with mutated EZH2 relapsed or refractory FL after ≥2 prior systemic therapies. It is also approved for those with relapsed or refractory FL who have no satisfactory alternative treatment options, regardless of their mutational status of EZH2. Currently, tazemetostat and its combination therapies for patients with relapsed or refractory germinal center-derived lymphomas, as well as frontline therapies for previously untreated patients, are in various phases of clinical investigations. Despite the promise of epigenetic therapies, potential pitfalls such as target selectivity, risk of oncogenic activation, risk of secondary malignancies associated with epigenetic therapies must be carefully monitored. Future applications of epigenetic approach that incorporate clinical and genomic features are needed to determine how individualized treatments can be used for these hematologic malignancies.

A Method for the Elution of Anti-CD20 With an EDTA/Glycine Acid Solution for Accurate Immunophenotyping of B Lymphocytes Sensitized With Rituximab

OBJECTIVES

To assess the efficacy of a method to circumvent CD20-positive antigen masking by rituximab for flow cytometry analysis of B-cell malignancies in hematology patients.

METHODS

Mononuclear cells (MNCs) from 10 healthy individuals and 5 untreated patients with B-cell malignancies were sensitized with rituximab. Patients' diagnoses included chronic lymphocytic leukemia, hairy cell leukemia, and follicular lymphoma. MNCs were isolated by gradient density centrifugation. An EDTA/glycine acid (EGA) elution method was used to dissociate CD20-rituximab complexes; afterwards, CD20-positive immunoreactivity was assessed by flow cytometry. A saturation curve was built based on serial dilutions of rituximab. Median fluorescent intensities of CD20-positive signals were obtained before sensitization with rituximab and after its elution with EGA.

RESULTS

CD20-positive signals were not detectable by flow cytometry after rituximab sensitization of B cells. CD20-sensitized vs CD20-unsensitized, CD20-sensitized vs CD20-eluted, and CD20-eluted vs CD20-negative control (NC) MNC populations exhibited statistical differences (P = .001), while CD20-sensitized vs CD20-NC populations did not (P = .499), confirming CD20 antigen masking by rituximab.

CONCLUSIONS

Rituximab interfered with the flow cytometry protocol for CD20 determination on normal and neoplastic B cells. The EGA method efficiently eluted rituximab, allowing for accurate identification of CD20-positive B cells.

The different predictive effects of the intensity and proportion of CD20 expression on the prognosis of B-lineage acute lymphocyte leukemia

The prognostic effects of the CD20 positivity have been studied extensively in B‐lineage acute lymphocyte leukemia (B‐ALL) patients, but the results remain controversial. The aim of this study is to investigate the different predictive effects of the intensity and proportion of CD20 expression on the prognosis for B‐ALL patients by retrospective analysis. The mean fluorescence intensity (MFI) and percentage of CD20 on B‐ALL cells from 206 patients with B‐ALL were dynamically measured by flow cytometry, and their optimal cut‐off values were determined using the receiver operating characteristic curve. Changes in MFI and percentage of CD20 at various time points and their relationship with prognosis were analyzed. We found that a low baseline CD20 MFI or high CD20 proportion was significantly associated with shorter 5‐year overall survival and progression‐free survival, and the combination of these two factors could more accurately predict worse survival for B‐ALL patients. Furthermore, low CD20 MFI or a high CD20 proportion had different predictive effects for ALL patients with different clinical characteristics and could serve as an independent risk factor for adverse prognosis. There were significant decreases in both the intensity and proportion of CD20 after recurrence in the absence of rituximab treatment, particularly with CD20 intensity. Notably, the decrease of CD20 intensity after recurrence indicated a more shortened survival time. Finally, we conclude that a low intensity or high proportion of CD20 expression may be used as an indicator for inferior prognosis for B‐ALL patients. CD20 intensity is more likely to be a more universal biomarker for worse prognosis.

Mutated RAS-associating proteins and ERK activation in relapse/refractory diffuse large B cell lymphoma

Diffuse large B cell lymphoma (DLBCL) is successfully treated with combination immuno-chemotherapy, but relapse with resistant disease occurs in ~ 40% of patients. However, little is known regarding relapsed/refractory DLBCL (rrDLBCL) genetics and alternative therapies. Based on findings from other tumors, we hypothesized that RAS-MEK-ERK signaling would be upregulated in resistant tumors, potentially correlating with mutations in RAS, RAF, or associated proteins. We analyzed mutations and phospho-ERK levels in tumor samples from rrDLBCL patients. Unlike other tumor types, rrDLBCL is not mutated in any Ras or Raf family members, despite having increased expression of p-ERK. In paired biopsies comparing diagnostic and relapsed specimens, 33% of tumors gained p-ERK expression, suggesting a role in promoting survival. We did find mutations in several Ras-associating proteins, including GEFs, GAPs, and downstream effectors that could account for increased ERK activation. We further investigated mutations in one such protein, RASGRP4. In silico modeling indicated an increased interaction between H-Ras and mutant RASGRP4. In cell lines, mutant RASGRP4 increased basal p-ERK expression and lead to a growth advantage in colony forming assays when challenged with doxorubicin. Relapsed/refractory DLBCL is often associated with increased survival signals downstream of ERK, potentially corresponding with mutations in protein controlling RAS/MEK/ERK signaling.

CD20 expression, TrkB activation and functional activity of diffuse large B cell lymphoma-derived small extracellular vesicles

BACKGROUND

Small extracellular vesicles (sEVs) including exosomes, carrying the CD20, could be involved in immunotherapy resistance in diffuse large B cell lymphoma (DLBCL). We have reported endogenous brain-derived neurotrophic factor/TrkB (tropomyosin-related kinase B) survival axis in DLBCL. Here, we performed a comparative study of sEV production by germinal centre B cell (GCB) and activated B cell (ABC)-DLBCL cell lines, and analysed TrkB activation on this process.

METHODS

GCB (SUDHL4 and SUDHL6) and ABC (OCI-LY3, OCI-LY10 and U2932) cell lines were used. sEVs were characterised using nanoparticle tracking analysis technology and western blot. CD20 content was also analysed by enzyme-linked immunoassay, and complement-dependent cytotoxicity of rituximab was investigated. 7,8-Dihydroxyflavone (7,8-DHF) was used as a TrkB agonist. In vivo role of sEVs was evaluated in a xenograft model.

RESULTS

sEVs production varied significantly between DLBCL cells, independently of subtype. CD20 level was consistent with that of parental cells. Higher CD20 expression was found in sEVs after TrkB activation, with a trend in increasing their concentration. sEVs determined in vitro and in vivo protection from rituximab, which seemed CD20 level-dependent; the protection was enhanced when sEVs were produced by 7,8-DHF-treated cells.

CONCLUSIONS

DLBCL-derived sEVs have the differential capacity to interfere with immunotherapy, which could be enhanced by growth factors like neurotrophins. Evaluating the sEV CD20 level could be useful for disease monitoring.

Nanomedicine for Immunotherapy Targeting Hematological Malignancies: Current Approaches and Perspective

Conventional chemotherapy has partial therapeutic effects against hematological malignancies and is correlated with serious side effects and great risk of relapse. Recently, immunotherapeutic drugs have provided encouraging results in the treatment of hematological malignancies. Several immunotherapeutic antibodies and cell therapeutics are in dynamic development such as immune checkpoint blockades and CAR-T treatment. However, numerous problems restrain the therapeutic effectiveness of tumor immunotherapy as an insufficient anti-tumor immune response, the interference of an immune-suppressive bone marrow, or tumoral milieu with the discharge of immunosuppressive components, access of myeloid-derived suppressor cells, monocyte intrusion, macrophage modifications, all factors facilitating the tumor to escape the anti-cancer immune response, finally reducing the efficiency of the immunotherapy. Nanotechnology can be employed to overcome each of these aspects, therefore having the possibility to successfully produce anti-cancer immune responses. Here, we review recent findings on the use of biomaterial-based nanoparticles in hematological malignancies immunotherapy. In the future, a deeper understanding of tumor immunology and of the implications of nanomedicine will allow nanoparticles to revolutionize tumor immunotherapy, and nanomedicine approaches will reveal their great potential for clinical translation.

Prognostic molecular biomarkers in diffuse large B-cell lymphoma in the rituximab era and their therapeutic implications

Diffuse large B-cell lymphoma (DLBCL) represents a group of tumors characterized by substantial heterogeneity in terms of their pathological and biological features, a causal factor of their varied clinical outcome. This variation has persisted despite the implementation of rituximab in treatment regimens over the last 20 years. In this context, prognostic biomarkers are of great importance in order to identify high-risk patients that might benefit from treatment intensification or the introduction of novel therapeutic agents. Herein, we review current knowledge on specific immunohistochemical or genetic biomarkers that might be useful in clinical practice. Gene-expression profiling is a tool of special consideration in this effort, as it has enriched our understanding of DLBCL biology and has allowed for the classification of DLBCL by cell-of-origin as well as by more elaborate molecular signatures based on distinct gene-expression profiles. These subgroups might outperform individual biomarkers in terms of prognostication; however, their use in clinical practice is still limited. Moreover, the underappreciated role of the tumor microenvironment in DLBCL prognosis is discussed in terms of prognostic gene-expression signatures, as well as in terms of individual biomarkers of prognostic significance. Finally, the efficacy of novel therapeutic agents for the treatment of DLBCL patients are discussed and an evidence-based therapeutic approach by specific genetic subgroup is suggested.

The regulation and function of CD20: an "enigma" of B-cell biology and targeted therapy

The introduction of anti-CD20 monoclonal antibodies such as rituximab, ofatumumab, or obinutuzumab improved the therapy of B-cell malignancies even though the precise physiological role and regulation of CD20 remains unclear. Furthermore, CD20 expression is highly variable between different B-cell malignancies, patients with the same malignancy, and even between intraclonal subpopulations in an individual patient. Several epigenetic (EZH2, HDAC1/2, HDAC1/4, HDAC6, complex Sin3A-HDAC1) and transcription factors (USF, OCT1/2, PU.1, PiP, ELK1, ETS1, SP1, NFκB, FOXO1, CREM, SMAD2/3) regulating CD20 expression (encoded by MS4A1) have been characterized. CD20 is induced in the context of microenvironmental interactions by CXCR4/SDF1 (CXCL12) chemokine signaling and the molecular function of CD20 has been linked to the signaling propensity of B-cell receptor (BCR). CD20 has also been shown to interact with multiple other surface proteins on B cells (such as CD40, MHCII, CD53, CD81, CD82, and CBP). Current efforts to combine anti-CD20 monoclonal antibodies with BCR signaling inhibitors targeting BTK or PI3K (ibrutinib, acalabrutinib, idelalisib, duvelisib) or BH3-mimetics (venetoclax) lead to the necessity to better understand both the mechanisms of regulation and the biological functions of CD20. This is underscored by the observation that CD20 is decreased in response to the "BCR inhibitor" ibrutinib which largely prevents its successful combination with rituximab. Several small molecules (such as histone deacetylase inhibitors, DNA methyl-transferase inhibitors, aurora kinase A/B inhibitors, farnesyltransferase inhibitors, FOXO1 inhibitors, and bryostatin-1) are being tested to upregulate cell-surface CD20 levels and increase the efficacy of anti-CD20 monoclonal antibodies. Herein, we review the current understanding of CD20 function, and the mechanisms of its regulation in normal and malignant B cells, highlighting the therapeutic implications.

Identification and Validation of a Novel Six-Gene Prognostic Signature of Stem Cell Characteristic in Colon Cancer

Cancer stem cells play crucial roles in the development of colon cancer (COAD). This study tried to explore new markers for predicting the prognosis of colon cancer based on stem cell-related genes. In our study, 424 COAD samples from TCGA were divided into three subtypes based on 412 stem cell-related genes; there were significant differences in prognosis, clinical characteristics, and immune scores between these subtypes. 694 genes were screened between subgroups. Subsequently a six-gene signature (DYDC2, MS4A15, MAGEA1, WNT7A, APOD, and SERPINE1) was established. This model had strong robustness and stable predictive performance in cohorts of different platforms. Taken together, the six-gene signature constructed in this study could be used as a novel prognostic marker for COAD patients.

Biomarkers and novel therapeutic approaches for diffuse large B-cell lymphoma in the era of precision medicine

Despite the great efforts for better treatment options for diffuse large B-cell lymphoma (DLBCL) (most common form of non-Hodgkin lymphoma, NHL) to treat and prevent relapse, it continues to be a challenge. Here, we present an overview of DLBCL and address the diagnostic assays and molecular techniques used in its diagnosis, role of biomarkers in detection, treatment of early and advanced stage DLBCL, and novel drug regimens. We discuss the significant biomarkers that have emerged as essential tools for stratifying patients according to risk factors and for providing insights into the use of more targeted and individualized therapeutics. We discuss techniques such as gene expression studies, including next-generation sequencing, which have enabled a more understanding of the complex pathogenesis of DLBCL and have helped determine molecular targets for novel therapeutic agents. We examine current treatment approaches, outline the findings of completed clinical trials, and provide updates for ongoing clinical trials. We highlight clinical trials relevant to the significant fraction of DLBCL patients who present with complex cases marked by high relapse rates. Supported by an increased understanding of targetable pathways in DLBCL, clinical trials involving specialized combination therapies are bringing us within reach the promise of an effective cure to DLBCL using precision medicine. Optimization of therapy remains a crucial objective, with the end goal being a balance between high survival rates through targeted and personalized treatment while reducing adverse effects in DLBCL patients of all subsets.

Monoclonal Antibody Therapies in Systemic Light-Chain Amyloidosis

In systemic light-chain amyloidosis, monoclonal antibodies target antigens that are either membrane-bound or circulating or deposited in the organs. CD38 holds high promise as a target against clonal plasma cells. Multiple anti-CD38 antibodies are either approved for use or being investigated in clinical trials. Daratumumab has been investigated and has clinical efficacy in upfront or refractory settings. High rates of hematologic response are seen with daratumumab, which translates to high organ response rates. Rituximab is usually integrated into the treatment regimen for IgM amyloidosis. Anti-amyloid therapies have shown preclinical proof of principle, but lack confirmation of improvement.

DA-EPOCH-R combined with high-dose methotrexate in patients with newly diagnosed stage II-IV CD5-positive diffuse large B-cell lymphoma: a single-arm, open-label, phase II study

CD5-positive diffuse large B-cell lymphoma (CD5+ DLBCL) is characterized by poor prognosis and a high frequency of central nervous system relapse after standard immunochemotherapy. We conducted a phase II study to investigate the efficacy and safety of dose-adjusted (DA)- EPOCH-R (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab) combined with high-dose methotrexate (HD-MTX) in newly diagnosed patients with CD5+ DLBCL. Previously untreated patients with stage II to IV CD5+ DLBCL according to the 2008 World Health Organization classification were eligible. Four cycles of DA-EPOCH-R followed by two cycles of HD-MTX and four additional cycles of DAEPOCH- R (DA-EPOCH-R/HD-MTX) were planned as the protocol treatment. The primary end point was 2-year progression-free survival (PFS). Between September 25, 2012, and November 11, 2015, we enrolled 47 evaluable patients. Forty-five (96%) patients completed the protocol treatment. There were no deviations or violations in the DA-EPOCH-R dose levels. The complete response rate was 91%, and the overall response rate was 94%. At a median follow up of 3.1 years (range, 2.0-4.9 years), the 2- year PFS was 79% [95% confidence interval (CI): 64-88]. The 2-year overall survival was 89% (95%CI: 76-95). Toxicity included grade 4 neutropenia in 46 (98%) patients, grade 4 thrombocytopenia 12 (26%) patients, and febrile neutropenia in 31 (66%) patients. No treatment-related death was noted during the study. DA-EPOCH-R/HD-MTX might be a first-line therapy option for stage II-IV CD5+ DLBCL and warrants further investigation. (Trial registered at: UMIN-CTR: UMIN000008507.).

Well-Orientation Strategy for Direct Immobilization of Antibodies: Development of the Immunosensor Using the Boronic Acid-Modified Magnetic Graphene Nanoribbons for Ultrasensitive Detection of Lymphoma Cancer Cells

This work presents an effective strategy for the well-oriented immobilization of antibodies in which boronic acid is directly attached to the surface and with no need of the long and flexible spacer. A magnetic graphene nanoribbon-boronic-acid-based immunosensor was developed and tested for the impedimetric detection of lymphoma cancer cells, a blood cancer biomarker. Magnetic graphene nanoribbons (MGNRs) were modified with boronic acid (BA) to create a supporting matrix that is utilized by immobilizing anti-CD20 antibodies with good orientation. The prepared biosensing layer (MGNR/BA/Ab) with well-oriented antibodies was premixed into whole blood samples to interact with lymphoma cancer cell receptors. In the presence of target cell receptors, an immunocomplex was formed between anti-CD20 antibodies and lymphoma cancer cell receptors. Then, the biosensing layer was magnetically collected on a screen-printed carbon electrode (SPCE) and placed in a homemade electrochemical cell configuration to measure impedimetric signals. The fabrication steps of the immunosensor were characterized by various techniques, such as resonance light scattering, fluorescence, electrochemical impedance spectroscopy, and cyclic voltammetry. The assay is highly sensitive: the calculated limit of detection of lymphoma cancer cells was as low as 38 cells/mL, and the detection was linear from 100 to 1 000 000 cells/mL. The specificity of the immunosensor is also very high, and there is no interference effect with several potential interferents, such as the breast cancer (MCF-7), human embryonic kidney (HEK293), and leukemia (HL-60 and KCL-22) cell lines. The performance of the immunosensor for lymphoma cancer cells in clinical blood samples is consistent with that of commercial flow cytometric assays.

HDAC inhibitors overcome immunotherapy resistance in B-cell lymphoma

Immunotherapy has been applied successfully to treat B-cell lymphomas in preclinical models or clinical settings. However, immunotherapy resistance is a major challenge for B-cell lymphoma treatment. To overcome this issue, combinatorial therapeutic strategies have been pursued to achieve a better efficacy for treating B-cell lymphomas. One of such strategies is to combine immunotherapy with histone deacetylase (HDAC) inhibitors. HDAC inhibitors can potentially increase tumor immunogenicity, promote anti-tumor immune responses, or reverse immunosuppressive tumor environments. Thus, the combination of HDAC inhibitors and immunotherapy has drawn much attention in current cancer treatment. However, not all HDAC inhibitors are created equal and their net effects are highly dependent on the specific inhibitors used and the HDACs they target. Hence, we suggest that optimal treatment efficacy requires personalized design and rational combination based on prognostic biomarkers and unique profiles of HDAC inhibitors. Here, we discuss the possible mechanisms by which B-cell lymphomas acquire immunotherapy resistance and the effects of HDAC inhibitors on tumor cells and immune cells that could help overcome immunotherapy resistance.

Drug Resistance in Cancer Therapy and the Role of Epigenetics

Effective leukemia treatment is seriously hampered by drug resistance, and the potential role of epigenetic mechanisms in cancer drug resistance has recently been investigated. With conventional anticancer drugs, including alkylating drugs, anti-metabolite drugs, topoisomerase inhibitors, and microtubule inhibitors-which have been available for half a century-drug resistance often develops because of decreased expression of target enzymes, in conjunction with increased expression of drug export pumps. Alterations of target gene expression and increased export pump function might be caused by epigenetic changes, such as alterations in methylation status, as well as by changes in histone acetylation status. In addition, newly developed anticancer drugs, including small-molecule drugs, such as kinase inhibitors, antibody drugs, and immune modulatory drugs, also resulted in development of drug resistance within 1 year, although these drugs showed significant effectiveness for patients resistant to conventional anticancer drugs. The resistant cells exhibited increased expression of bypass pathways, activation of downstream cascades, decreased expression of antigens of tumor cells, increased DNA repair activity, and increased expression of drug export pumps, which also suggests the presence of epigenetic changes. This article reviews drug resistance in cancer therapy and the possible roles of epigenetic mechanisms.

The therapeutic effectiveness of 177Lu-lilotomab in B-cell non-Hodgkin lymphoma involves modulation of G2/M cell cycle arrest

Some patients with B-cell non-Hodkin lymphoma Lymphoma (NHL) become refractory to rituximab (anti-CD20 antibody) therapy associated with chemotherapy. Here, the effect of the anti-CD37 antibody-radionuclide conjugate lutetium-177 (¹⁷⁷Lu)-lilotomab (Betalutin^®) was investigated in preclinical models of NHL. In SCID mice bearing DOHH2 (transformed follicular lymphoma, FL) cell xenografts, ¹⁷⁷Lu-lilotomab significantly delayed tumor growth, even at low activity (100 MBq/kg). In athymic mice bearing OCI-Ly8 (diffuse large B-cell lymphoma, DLBCL) or Ramos (Burkitt’s lymphoma) cell xenografts, ¹⁷⁷Lu-lilotomab activity had to be increased to 500 MBq/kg to show a significant tumor growth delay. Clonogenic and proliferation assays showed that DOHH2 cells were highly sensitive to ¹⁷⁷Lu-lilotomab, while Ramos cells were the least sensitive, and U2932 (DLBCL), OCI-Ly8, and Rec-1 (mantle cell lymphoma) cells displayed intermediate sensitivity. The strong ¹⁷⁷Lu-lilotomab cytotoxicity observed in DOHH2 cells correlated with reduced G2/M cell cycle arrest, lower WEE-1- and MYT-1-mediated phosphorylation of cyclin-dependent kinase-1 (CDK1), and higher apoptosis. In agreement, ¹⁷⁷Lu-lilotomab efficacy in vitro, in vivo, and in patient samples was increased when combined with G2/M cell cycle arrest inhibitors (MK-1775 and PD-166285). These results indicate that ¹⁷⁷Lu-lilotomab is particularly efficient in treating tumors with reduced inhibitory CDK1 phosphorylation, such as transformed FL.

CD5 expression correlates with inferior survival and enhances the negative effect of p53 overexpression in diffuse large B-cell lymphoma

De novo CD5-positive diffuse large B-cell lymphoma (CD5+ DLBCL) is increasingly recognized as a distinct pathologic phenomenon with a specific clinical picture. However, CD5+ DLBCL has not been studied on a large scale in China. In this study, we show that CD5+ DLBCL occurs at a low frequency (9.2%). Comparison of clinical characteristics of CD5+ vs CD5- DLBCL showed that CD5+ DLBCL was more frequently elderly (>60 years) and had B symptoms, high-performance status, stage III-IV, an IPI score >2 and bone marrow involvement. Patients with CD5+ DLBCL had tumours with a higher prevalence of BCL-2 and p53 overexpression than CD5- DLBCL. Patients with CD5+ DLBCL had inferior progression-free survival (PFS) and overall survival (OS) than did patients with CD5- DLBCL. For CD5+ DLBCL, the patients who were treated with rituximab showed significantly better PFS and OS than those treated without rituximab. However, patients treated with RCHOP showed similar PFS and OS when compared with the group treated with intensive therapy. In addition, patients with p53 and CD5 co-expression had the worst PFS and OS. In conclusion, CD5+ DLBCL was associated with unfavorable clinicopathologic variables and with inferior survival. CD5+ DLBCL has a high frequency of p53 overexpression, and CD5 augments the negative effect of p53 overexpression in DLBCL.

Enhancing FcγR-mediated antibody effector function during persistent viral infection

Persistent viral infections can interfere with FcγR-mediated antibody effector functions by excessive immune complex (IC) formation, resulting in resistance to therapeutic FcγR-dependent antibodies. We and others have previously demonstrated that mice persistently infected with lymphocytic choriomeningitis virus (LCMV) are resistant to a wide range of depleting antibodies due to excessive IC formation. Here, we dissect the mechanisms by which two depleting antibodies overcome the obstacle of endogenous ICs and achieve efficient target cell depletion in persistently infected mice. Efficient antibody-mediated depletion during persistent LCMV infection required increased levels of antibody bound to target cells or use of afucosylated antibodies with increased affinity for FcγRs. Antibodies targeting the highly expressed CD90 antigen or overexpressed human CD20 efficiently depleted their target cells in naïve and persistently infected mice, whereas antibodies directed against less abundant antigens failed to deplete their target cells during persistent LCMV infection. In addition, we demonstrate the superior activity of afucosylated antibodies in the presence of endogenous ICs. We generated afucosylated antibodies directed against CD4 and CD8α, which, in contrast to their parental fucosylated versions, efficiently depleted their respective target cells in persistently infected mice. Efficient antibody-mediated depletion can thus be achieved if therapeutic antibodies can outcompete endogenous ICs for access to FcγRs either by targeting highly expressed antigens or by increased affinity for FcγRs. Our findings have implications for the optimization of therapeutic antibodies and provide strategies to allow efficient FcγR engagement in the presence of competing endogenous ICs in persistent viral infections, autoimmune diseases, and cancer.

Development of a simple new flow cytometric antibody-dependent cellular cytotoxicity (ADCC) assay with excellent sensitivity

Antibody-based therapeutic strategies have become recognized as useful clinical options in several types of cancer, often with the expectation that such therapies will trigger target cell elimination via antibody-dependent cellar cytotoxicity (ADCC) by natural killer cells. The successful development of therapeutic monoclonal antibodies (mAbs) requires an assay system that permits a critical evaluation of their physicochemical and biological characteristics. At present a number of ADCC assay systems have been reported, however, there is still room for improvement in terms of usability, operability and sensitivity. Here we report a novel flow cytometric ADCC assay that uses a human natural killer cell line stably transfected with mouse FcγRIII, and Fc receptor common-γ chain (FcRγ) and a reporter gene as effector cells. This assay relies on discriminating effector and target cells by their differential immunofluorescence, which allows for clear-cut gating and accurate calculation of the number of surviving cells in a target population. This assay is easy and quick to perform and provides reliable data even for low frequency target cells in assay samples and with low concentrations of mAbs. Furthermore, our approach allows us to identify synergistic ADCC activity of mAbs with different epitope specificities on the same target antigen.

Successful Treatment of Aggressive Mature B-cell Lymphoma Mimicking Immune Thrombocytopenic Purpura

A 55-year-old woman suffered from hemorrhagic tendency. She had severe thrombocytopenia without any hematological or coagulatory abnormalities, and a bone marrow examination revealed an increased number of megakaryocytes without any abnormal cells or blasts. No lymphadenopathy or hepatosplenomegaly was observed on computed tomography. She was initially diagnosed with immune thrombocytopenic purpura (ITP). None of the treatments administered for ITP produced a response. However, abnormal cells were eventually found during the third bone marrow examination. The pathological diagnosis was mature B-cell lymphoma. Rituximab-containing chemotherapy produced a marked increase in the patient's platelet count, and her lymphoma went into complete remission.

Epstein-Barr Virus–Positive CD20- and CD45-Negative Diffuse Large B-Cell Lymphoma: A Diagnostic Challenge

Diffuse large B-cell lymphoma (DLBCL) is characterized by medium- to large-sized neoplastic cells that express a wide range of B-cell markers including CD19, CD20, CD22, and CD79a. Also, as this is a hematopoietic malignancy, there is expression of the leukocyte common antigen CD45. Lack of CD20 expression occurs in a specific rare heterogeneous subgroup of DLBCL including primary effusion lymphoma, plasmablastic lymphoma, ALK-positive large B-cell lymphoma, and large B-cell lymphoma arising in HHV8+ multicentric Castleman disease. In this article, we report a rare case of CD20- and CD45-negative Epstein-Barr virus–positive DLBCL in which the entities listed above were ruled out, thereby posing a significant diagnostic challenge. Arriving at the correct diagnosis of Epstein-Barr virus–positive DLBCL was supported by immunoreactivity for the B-cell transcription factor Oct-2 and the pan-B cell marker CD79a.

Past, Present, and Future of Rituximab-The World's First Oncology Monoclonal Antibody Therapy

Rituximab is a chimeric mouse/human monoclonal antibody (mAb) therapy with binding specificity to CD20. It was the first therapeutic antibody approved for oncology patients and was the top-selling oncology drug for nearly a decade with sales reaching $8.58 billion in 2016. Since its initial approval in 1997, it has improved outcomes in all B-cell malignancies, including diffuse large B-cell lymphoma, follicular lymphoma, and chronic lymphocytic leukemia. Despite widespread use, most mechanistic data have been gathered from in vitro studies while the roles of the various response mechanisms in humans are still largely undetermined. Polymorphisms in Fc gamma receptor and complement protein genes have been implicated as potential predictors of differential response to rituximab, but have not yet shown sufficient influence to impact clinical decisions. Unlike most targeted therapies developed today, no known biomarkers to indicate target engagement/tumor response have been identified, aside from reduced tumor burden. The lack of companion biomarkers beyond CD20 itself has made it difficult to predict which patients will respond to any given anti-CD20 antibody. In the past decade, two new anti-CD20 antibodies have been approved: ofatumumab, which binds a distinct epitope of CD20, and obinutuzumab, a mAb derived from rituximab with modifications to the Fc portion and to its glycosylation. Both are fully humanized and have biological activity that is distinct from that of rituximab. In addition to these new anti-CD20 antibodies, another imminent change in targeted lymphoma treatment is the multitude of biosimilars that are becoming available as rituximab's patent expires. While the widespread use of rituximab itself will likely continue, its biosimilars will increase global access to the therapy. This review discusses current research into mechanisms and potential biomarkers of rituximab response, as well as its biosimilars and the newer CD20 binding mAb therapies. Increased ability to assess the effectiveness of rituximab in an individual patient, along with the availability of alternative anti-CD20 antibodies will likely lead to dramatic changes in how we use CD20 antibodies going forward.

Distinct Expression and Prognostic Value of MS4A in Gastric Cancer

Gastric cancer has high malignancy and early metastasis, which lead to poor survival rate. In this study, we assessed the expressions and prognostic values of MS4A family, a newly recently discovered family, by two online dataset, GEPIA and Kaplan Meier-plotter. From these results eight members, MS4A2, MS4A6, MS4A7, MS4A8, MS4A14, MS4A15, TMEM176A and TMEM176B showed positive expression in gastric cancer or normal tissues, and these genes were screened for further analysis of prognostic values. We observed that low mRNA expressions of MS4A2, MS4A7, MS4A14, MS4A15, TMEM176A and TMEM176B were correlated with better overall survival (OS) in all gastric cancer patients, while high mRNA expression of MS4A6 was observed to be associated with good prognosis. MS4A8’s high mRNA level was correlated to better OS in diffuse gastric cancer patients. Further, we estimated prognostic values of MS4A family in gastric cancer patients with different clinic-pathological features, including clinical stages, differentiation level, lymph node status and HER2 status. Our results indicate that these eight MS4A members can estimate prognosis in patients with different pathological groups. In conclusion, MS4A family members are potential biomarkers, and may contribute to tumor progression in gastric cancer.

Prognostication of diffuse large B-cell lymphoma in the molecular era: moving beyond the IPI

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease with variable outcomes. Despite the majority of patients being cured with combination chemoimmunotherapy, up to 30% eventually succumb to the disease. Until recently, baseline prognostic assessment has centred on the International Prognostic Index (IPI), although this index is yet to impact strongly on treatment choice. Molecular features such as cell of origin, MYC and BCL-2 genetic alterations and protein overexpression were identified over a decade ago, yet their prognostic value is still not fully elucidated. Adding complexity are the plethora of new clinical, biological and molecular prognostic markers described in the recent literature, most of which lack independent validation, likely act as surrogate markers for those already in common use and have yet to substantially impact on therapeutic decision making. This review comprehensively assesses the value of individual prognostic markers in the clinical setting and their potential to predict response to novel agents, and ways to optimise their use in future research.

Comparison of the algorithms classifying the ABC and GCB subtypes in diffuse large B-cell lymphoma

Different immunohistochemical algorithms for the classification of the activated B-cell (ABC) and germinal center B-cell (GCB) subtypes of diffuse large B-cell lymphoma (DLBCL) are applied in different laboratories. In the present study, 127 patients with DLCBL were investigated, all treated with rituximab and cyclophosphamide, hydroxydaunorubicin, oncovin and prednisone (CHOP) or CHOP-like regimens between April 2004 and December 2010. Multi-tumor tissue microarrays were prepared and were tested according to 4 algorithms: Hans; modified Hans; Choi; and modified Choi. For 39 patients, the flow cytometric quantification of CD19 and CD20 antigen expression was performed and the level of expression presented as molecules of equivalent soluble fluorochrome units. The Choi algorithm was demonstrated to be prognostic for OS and classified patients into the GCB subgroup with an HR of 0.91. No difference in the expression of the CD19 antigen between the ABC and GCB groups was observed, but the ABC subtype exhibited a decreased expression of the CD20 antigen compared with the GCB subtype.

Identification of relevant drugable targets in diffuse large B-cell lymphoma using a genome-wide unbiased CD20 guilt-by association approach

Forty percent of patients with diffuse large B-cell lymphoma (DLBCL) show resistant disease to standard chemotherapy (CHOP) in combination with the anti-CD20 monoclonal antibody rituximab (R). Although many new anti-cancer drugs were developed in the last years, it is unclear which of these drugs can be safely combined to improve standard therapy without antagonizing anti-CD20 efficacy. In this study, we aimed to identify rituximab compatible drug-target combinations for DLBCL. For this, we collected gene expression profiles of 1,804 DLBCL patient samples. Subsequently, we performed a guilt-by-association analysis with MS4A1 (CD20) and prioritized the 500 top-ranked CD20-associated gene probes for drug-target interactions. This analysis showed the well-known genes involved in DLBCL pathobiology, but also revealed several genes that are relatively unknown in DLBCL, such as WEE1 and PARP1. To demonstrate potential clinical relevance of these targets, we confirmed high protein expression of WEE1 and PARP1 in patient samples. Using clinically approved WEE1 and PARP1 inhibiting drugs in combination with rituximab, we demonstrated significantly improved DLBCL cell killing, also in rituximab-insensitive cell lines. In conclusion, as exemplified by WEE1 and PARP1, our CD20-based genome-wide analysis can be used as an approach to identify biological relevant drug-targets that are rituximab compatible and may be implemented in phase 1/2 clinical trials to improve DLBCL treatment.

Cd20 Expression and Effects on Outcome of Relapsed/ Refractory Diffuse Large B Cell Lymphoma after Treatment with Rituximab

Introduction:

Down regulation of CD20 expression has been reported in diffuse large B cell lymphoma (DLBCL)). Therefore, it is important to determine whether chemotherapy with rituximab induces CD20 down regulation and effects survival.

Objectives:

To determine the incidence of down regulation of CD20 expression in relapsed DLBCL after treatment with rituximab and to compare outcomes and assess pattern of relapse between CD20 negative and CD20 positive cases.

Methodology:

We retrospectively reviewed patients with relapsed DLBCL who received rituximab in the first line setting at Aga Khan University Hospital between January 2007 and December 2014. Data were recorded on predesigned questionnaires, with variables including demographics, details regarding date of diagnosis and relapse, histology, staging, international prognostic index, treatment and outcomes at initial diagnosis and at relapse. The Chi square test was applied to determine statistical significance between categorical variables. Survival curves were generated by the Kaplan–Meier method.

Results:

A total of 54 patients with relapsed DLBCL were included in our study, 38 (70 %) males and 16(30%) females. Some 23 (43%) patients were at stage IV at the time of diagnosis and 34 (63%) had B symptoms. The most frequent R-IPI at diagnosis was II in 24 (44%) patients. Only 6 (11%) did not show CD20 expression on re-biopsy for relapsed/refractory disease, 2 with CD20 negative DLBCL responding to second line chemotherapy. A complete response after salvage chemotherapy was noted in 16 (29.6%) cases with relapsed/refractory DLBCL. Seven (13%) patients underwent an autologous bone marrow transplant as consolidation after second line treatment. Median overall survival was 18 months in CD20 positive vs. 13 months in CD20 negative patients.

Conclusion:

This study demonstrated that a small percentage of patients treated with rituximab lose their CD20 expression at the time of relapse. However, it is unclear whether this is associated with an inferior outcome.

Differential gene expression profiling linked to tumor progression of splenic marginal zone lymphoma

The genetic events that lead to aggressive transformation of cases of splenic marginal zone lymphoma (SMZL) after the chronic clinical stage have not been well understood. We aimed to find candidate genes associated with aggressive features of SMZL. We have successfully established two SMZL cell lines, designated SL-15 and SL-22, derived from the same patient's tumor clone in chronic and aggressive phases, respectively. Microarray analysis identified cell cycle-associated genes-specifically PLK1-as the most significantly upregulated in primary aggressive SMZL cells compared with cells from chronic phase. EPHA4 and MS4A1 (CD20) were found to be downregulated dramatically. These gene expression patterns were reproduced in both cell lines. Genetic knockdown of PLK1 resulted in inhibition of cell proliferation and induction of apoptosis in SL-22 cells, which expressed higher levels of PLK1 than SL-15 cells. SL-22 cells needed higher concentrations of chemical PLK1 inhibitors to achieve greater effects. In addition, we found homozygous deletion of the MS4A1 gene as a newly identified molecular mechanism of CD20-negative conversion. Our findings are expected to stimulate further studies on whether PLK1 could be a potential therapeutic target for this tumor. Furthermore, cases with CD20-negatively converted lymphomas should be screened for the genomic loss of MS4A1.

Clinical characteristics and prognostic factors of plasmablastic lymphoma patients: analysis of 135 patients from the LYSA group

Background

Plasmablastic lymphoma (PBL), initially described in 1997 in the oral cavity of HIV positive patients, is now recognized as a distinct aggressive and rare entity of diffuse large B-cells lymphoma by the World Health Organization (WHO) classification. Since the original description, others cases have been reported. However, these are largely derived from case reports or small series limiting any definitive conclusions on clinical characteristics and outcome.

Patients and methods

The clinical, biological, pathological features and outcome of a cohort including 135 patients with PBL, from LYSA centers in France and Belgium, were reported and analyzed.

Results

The median age was 58 years, with a male predominance. The cohort was divided into 56 HIV-positive patients, 17 post-transplant patients and 62 HIV-negative/non-transplanted patients. Within HIV-negative/non-transplanted, a relative immunosuppression was found in most cases (systemic inflammatory disease, history of cancer, increased age associated with weakened immune system). We have also described a new subtype, PBL arising in a chronic localized inflammatory site, without any sign of immunosuppression. At presentation, 19% of patients showed oral involvement. Immunophenotype showed CD138 positivity in 88% of cases and CD20 negativity in 90% of cases. Chemotherapy was administered to 80% of patients, with a complete response (CR) rate of 55%. The median overall survival (OS) was 32 months. In univariate analysis, HIV positive status showed better OS when compared with HIV negative status. In multivariate analysis, International Prognostic Index score, chemotherapy and CR were associated with survival benefit.

Conclusion(s)

This cohort, the largest reported to date, increases the spectrum of knowledge on PBL, rarely described. However, specific guidelines to clarify treatment are lacking, and may improve the poor prognosis of this rare disease.

Genetic and Epigenetic Modulation of CD20 Expression in B-Cell Malignancies: Molecular Mechanisms and Significance to Rituximab Resistance

CD20 is a differentiation related cell surface phosphoprotein that is expressed during early pre-B cell stages until plasma cell differentiation, and is a suitable molecular target for B-cell malignancies by monoclonal antibodies such as rituximab, ofatumumab, obinutuzumab and others. CD20 expression is confirmed in most B-cell malignancies; however, the protein expression level varies in each patient, even in de novo tumors, and down-modulation of CD20 expression after chemoimmunotherapy with rituximab, resulting in rituximab resistance, has been recognized in the clinical setting. Recent reports suggest that genetic and epigenetic mechanisms are correlated with aberrantly low CD20 expression in de novo tumors and relapsed/refractory disease after using rituximab. Furthermore, some targeting drugs, such as lenalidomide, bortezomib and ibrutinib, directly or indirectly affect CD20 protein expression. CD20-negative phenotypically-changed DLBCL after rituximab use tends to show an aggressive clinical course and poor outcome with resistance to not only rituximab, but also conventional salvage chemo-regimens. Understanding of the mechanisms of CD20-negative phenotype may contribute to establish strategies for overcoming chemo-refractory B-cell malignancies. In this manuscript, recent progress of research on molecular and clinical features of CD20 protein and CD20-negative B-cell malignancies was reviewed.

An unusual case of Epstein-Barr virus-positive large B-cell lymphoma lacking various B-cell markers

Backgroud

Epstein-Barr virus (EBV) is associated with B-cell lymphoma in various conditions, such as immunodeficiency and chronic inflammation. We report an unusual case of EBV-positive diffuse large B-cell lymphoma (DLBCL) lacking the expression of many B-cell markers.

Case presentation

An 83-year-old man presented with a submandibular tumor. Histology of a lymph node biopsy specimen revealed diffuse proliferation of centroblast- or immunoblast-like lymphoid cells with plasmacytic differentiation. Scattered Hodgkin/Reed-Sternberg-like cells were also visible. A routine immunohistochemistry antibody panel revealed that the tumor cells were negative for B-cell and T-cell markers (i.e., CD3, CD19, CD20, CD38, CD45RO, CD79a, CD138, and Pax-5), but were positive for CD30 and MUM-1, not defining the lineage of tumor cells. The final diagnosis of EBV-positive DLBCL was confirmed based on the expression of B-cell-specific transcription factors (Oct-2 and BOB.1), PCR-based identification of monoclonal rearrangement of the immunoglobulin genes, and the presence of EBV-encoded small RNAs in the tumor cells (identified using in situ hybridization).

Conclusion

The downregulation of broad band of B-cell markers in the present case with EBV-positive DLBCL posed a diagnostic dilemma, as the possible diagnoses included differentiation from anaplastic large cell lymphoma and CD20-negative B-cell lymphomas. Results of immunohistochemical panel including B-cell-specific transcription factors and gene rearrangement analyses critically support the correct diagnosis.

Recipient-derived EBV-positive Monomorphic Plasmacytoma Type Posttransplant Lymphoproliferative Disorder After Allogeneic Stem Cell Transplant for Severe Aplastic Anemia: A Case Report

Monomorphic plasmacytoma-type posttransplant lymphoproliferative disorder (PTLD) has not been reported after pediatric hematopoietic stem cell transplantation. We present a child with hepatitis-associated severe aplastic anemia who underwent an unrelated allogeneic hematopoietic stem cell transplantation and subsequently developed graft failure and an Epstein-Barr virus-positive monomorphic plasmacytoma-type PTLD of recipient origin. Despite broad-spectrum antimicrobials, weaning immunosuppression, rituximab administration, and a stem cell boost she died from complications of PTLD and a fungal pulmonary infection on day +78.