Expression of PD-1 (CD279) and FoxP3 in diffuse large B-cell lymphoma

Non-neoplastic cells as prognostic biomarkers in diffuse large B-cell lymphoma: A system review and meta-analysis

The microenvironment of diffuse large B-cell lymphoma (DLBCL) is composed of various components, including immune cells and immune checkpoints, some of which have been correlated with the prognosis of DLBCL, but their results remain controversial. Therefore, we conducted a systematic review and meta-analysis to investigate the association between the microenvironment and prognosis in DLBCL. We searched PubMed, Web of Science, and EMBASE for relevant articles between 2001 and 2022. Twenty-five studies involving 4495 patients with DLBCL were included in the analysis. This meta-analysis confirmed that high densities of Foxp3+Tregs and PD-1+T cells are good indicators for overall survival (OS) in DLBCL, while high densities of programmed cell death protein ligand1(PD-L1)-positive expression cells and T-cell immunoglobulin-and mucin domain-3-containing molecule 3 (TIM-3)-positive expression tumor-infiltrating cells (TILs) play a contrary role in OS. Additionally, higher numbers of T-cell intracytoplasmic antigen-1(TIA-1)-positive expression T cells imply better OS and progression-free survival (PFS), while high numbers of lymphocyte activation gene(LAG)-positive expression TILs predict bad OS and PFS. Various non-tumoral cells in the microenvironment play important roles in the prognosis of DLBCL.

The Prognostic Impact of Tumor Microenvironment and Checkpoint Blockade-Associated Molecules (PD-1, PD-L1, CD163 and CD14) in Nodal Diffuse Large B-cell Lymphoma, NOS

It is aimed to determine expression of programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), CD163 and CD14 in diffuse large B-cell lymphomas (DLBCL), and whether these markers may predict prognosis in DLBCL cases. A total of 52 nodal DLBCL, NOS cases with no known extranodal involvement at the time of diagnosis were evaluated. PD-1, PD-L1, CD163, and CD14 were studied by immunohistochemistry. The relationships between the results and clinical and laboratory prognostic markers were investigated. It was observed that patients with PD-1 expression < 5 positive cells/HPF had worse overall survival. No significant relationship was found between survival and PD-L1, CD163 and CD14 expressions. In addition, cases that are > 60 years of age, that have Eastern Cooperative Oncology Group (ECOG) performance score ≥ 2, stage IV disease, high International Prognostic Index score score (≥ 3), elevation of LDH, low albumin level, low hemoglobin level, low peripheral blood lymphocyte count, high peripheral blood neutrophil/lymphocyte ratio, high peripheral blood platelet/lymphocyte ratio were found to have worse overall survival. It was concluded that in patients with low number of PD-1 positive tumor-infiltrating lymphocytes have low survival rates and therefore PD-1 expression may be useful in indicating prognosis.

Expression of the immune checkpoint molecules PD‑L1 and PD‑1 in EBV‑associated lymphoproliferative disorders: A meta‑analysis

Epstein-Barr virus (EBV) has been implicated in the development of a wide range of lymphoproliferative disorders. In this process, the role of programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) has remained to be clarified. A meta-analysis of 20 studies was performed and risk ratios (RRs) with 95% confidence intervals (CIs) were used to evaluate the association between PD-L1/PD-1 expression and the status of EBV infection. The results showed that the expression level of PD-L1 in tumor cells was significantly higher in EBV+ cases with a pooled RR of 2.26 (95% CI, 1.63-3.14; P<0.01), particularly in subtypes of diffuse large B-cell lymphoma (DLBCL) and classical Hodgkin lymphoma. Similarly, EBV infection increased the expression of PD-L1 in immune cells with a pooled RR of 2.20 (95% CI, 1.55-3.12; P<0.01). In subtypes of DLBCL and post-transplant lymphoproliferative disorder, the expression of PD-L1 in immune cells is increased in EBV+ cases. Regarding the expression level of PD-1 in tumor-infiltrating lymphocytes (TILs), no significance was found between EBV infection and PD-1 expression, with a pooled RR of 1.10 (95% CI, 0.81-1.48; P>0.05). The present meta-analysis demonstrated that in EBV-associated lymphoproliferative disorders, EBV infection was associated with the expression level of PD-L1 in tumor cells and immune cells but was not associated with the expression of PD-1 in TILs.

PD-L1 expression predicts efficacy in the phase II SPiReL trial with MVP-S, pembrolizumab, and low-dose CPA in R/R DLBCL

BACKGROUND

Patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) have limited treatment options.

METHODS

R/R DLBCL patients, who were mostly ineligible for ASCT due to age or comorbidities, were treated with maveropepimut-S (MVP-S, previously DPX-Survivac) a survivin directed T cell educating therapy, pembrolizumab, and intermittent low-dose cyclophosphamide.

FINDINGS

We identified, using univariate analysis, a subset of patients with enhanced ORR, PFS and DOR. Patients with baseline CD20+/PD-L1 expression had an ORR of 46% (6/13) and the disease control rate was 10/13 (77%). The PFS and OS of the positive CD20+/PD-L1 patients were 7.1 months and 17.4 months, whereas in the intent-to-treat (ITT) population of 25 enrolled patients, the ORR was 28% (7/25), median PFS and OS were 4.2 months and 10.1 months respectively. A total of 6/7 clinical responders occurred in CD20+/PD-L1 patients. The regimen was well-tolerated, requiring only minor dose modifications and one discontinuation. Grade 1 or 2 injection site reactions occurred in 14/25, (56%). Statistically significant associations were also seen between PFS and; injection site reactions; and ELISpot response to survivin peptides, both identifying the mechanistic importance of specific immune responses to survivin.

INTERPRETATION

This immunotherapy combination was found to be active and safe in this clinically challenging patient population.

Identification and Development of a 4-Gene Ferroptosis Signature Predicting Overall Survival for Diffuse Large B-Cell Lymphoma

Background: Diffuse large B-cell lymphoma (DLBCL) is a well-differentiated disease, which makes the diagnosis and therapeutic strategy a difficult problem. While ferroptosis, as an iron-dependent form of regulated cell death, it plays an important role in causing several types of cancer. This study is aimed at exploring the prognostic value of ferroptosis-related genes in DLBCL. Methods: In our study, mRNA expression and matching clinical data of DLBCL patients were derived from Gene Expression Omnibus (GEO) database. First, multivariate cox regression model and nomogram which can predict the DLBCL patients' prognosis were built and validated. The multigene signature was constructed and optimized by the least absolute shrinkage and selection operator (LASSO) cox regression model. Also, ferroptosis-related subtypes were developed by consistent cluster. Last but not least, we explored the association between categories of infiltrating immune cells and model genes' expression. Results: Our results showed that 27 gene expressions were correlated with overall survival (OS) in the univariate cox regression analysis. A 4-gene signature was constructed through these genes to stratify patients into high-low risk groups using risk score derived from model (model 1:gene expression model). The OS of patients in the high-risk group was shorter than that of patients in the low-risk group in the TNM stage and clinically distinct subtypes (activated B cell [ABC], germinal center B cell [GCB]) (P < .001). Furthermore, it was shown that the risk score was an independent factor in clinical cox regression model for OS (model 2:clinical model) (HR>1, P < .010). Besides, in consistent cluster analysis, ferroptosis prognosis status was different among 3 subtypes. Moreover, the correlation analysis between 4-gene with immune cells showed dendritic cells may be significantly associated with DLBCL. Conclusion: This research constructed an innovative ferroptosis-related gene signature for prognostic estimation of DLBCL patients. Solutions targeting ferroptosis could be an important therapeutic intervention for DLBCL.

Increased PD-1+Foxp3+ γδ T cells associate with poor overall survival for patients with acute myeloid leukemia

Problems

γδ T cells are essential for anti-leukemia function in immunotherapy, however, γδ T cells have different functional subsets, including regulatory cell subsets expressing the Foxp3. Whether they are correlated with immune-checkpoint mediated T cell immune dysfunction remains unknown in patients with acute myeloid leukemia (AML).

Methods

In this study, we used RNA-seq data from 167 patients in TCGA dataset to analyze the correlation between PD-1 and FOXP3 genes and these two genes' association with the prognosis of AML patients. The expression proportion of Foxp3⁺/PD-1⁺ cells in γδ T cells and two subgroups Vδ1 and Vδ2 T cells were performed by flow cytometry. The expression level of FOXP3 and PD-1 genes in γδ T cells were sorted from peripheral blood by MACS magnetic cell sorting technique were analyzed by quantitative real-time PCR.

Results

We found that PD-1 gene was positively correlated with FOXP3 gene and highly co-expressed PD-1 and FOXP3 genes were associated with poor overall survival (OS) from TCGA database. Then, we detected a skewed distribution of γδ T cells with increased Vδ1 and decreased Vδ2 T cell subsets in AML. Moreover, significantly higher percentages of PD-1⁺ γδ, Foxp3⁺ γδ, and PD-1⁺Foxp3⁺ γδ T cells were detected in de novo AML patients compared with healthy individuals. More importantly, AML patients containing higher PD-1⁺Foxp3⁺ γδ T cells had lower OS, which might be a potential therapeutic target for leukemia immunotherapy.

Conclusion

A significant increase in the PD-1⁺Foxp3⁺ γδ T cell subset in AML was associated with poor clinical outcome, which provides predictive value for the study of AML patients.

Prognostic value of FOXP3+ regulatory T cells in patients with diffuse large B-cell lymphoma: a systematic review and meta-analysis

OBJECTIVES

We aimed to comprehensively evaluate the relationship between forkhead box P3 (FOXP3+) regulatory T cell (Treg) expression and diffuse large B-cell lymphoma (DLBCL) prognosis and to explore the sources of heterogeneity of the results.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

We searched the Cochrane Library, PubMed, Embase and Web of Science databases up to 5 December 2021.

ELIGIBILITY CRITERIA

We included studies that analysed the prognostic significance of FOXP3+ Tregs in DLBCL. We included studies reported in Chinese or English that reported HRs and related 95% CIs for prognosis.

DATA EXTRACTION AND SYNTHESIS

We extracted data from eligible studies. HRs and 95% CIs were used to assess the prognostic value.

RESULTS

Fourteen eligible studies were identified. FOXP3+ Treg expression was not associated with overall survival (OS) (HR=0.72, 95% CI 0.45 to 1.16) or progression-free survival (HR=0.86, 95% CI 0.54 to 1.38). The three approaches used to measure FOXP3+ Treg expression (pinteraction<0.001) may be the source of the heterogeneity of the results. Subgroup analysis found that a higher expression of FOXP3+ Tregs was associated with better OS in all populations and in Asians when FOXP3+ Treg expression was measured by the number of positive cells (HR=0.36 (95% CI 0.22 to 0.58) in the former, HR=0.33 (95% CI 0.20 to 0.55) in the latter) or the percentage of positive cells (HR=0.49 (95% CI 0.27 to 0.89) in the former, HR=0.38 (95% CI 0.21 to 0.70) in the latter). However, when measured by the score, inverse results were found (HR=1.56, 95% CI 1.01 to 2.42).

CONCLUSIONS

Approaches to measuring FOXP3+ Treg expression might be the major source of heterogeneity in studies of the prognostic significance of FOXP3+ Tregs in DLBCL. FOXP3+ Treg expression might be used to predict the prognosis of patients with DLBCL when FOXP3+ Treg expression is calculated by the number or the percentage of positive cells, especially in Asian populations.

Regulatory T cells (Tregs) in lymphoid malignancies and the impact of novel therapies

Regulatory T cells (Tregs) are responsible for maintaining immune homeostasis by controlling immune responses. They can be characterized by concomitant expression of FoxP3, CD25 and inhibitory receptors such as PD-1 and CTLA-4. Tregs are key players in preventing autoimmunity and are dysregulated in cancer, where they facilitate tumor immune escape. B-cell lymphoid malignancies are a group of diseases with heterogenous molecular characteristics and clinical course. Treg levels are increased in patients with B-cell lymphoid malignancies and correlate with clinical outcomes. In this review, we discuss studies investigating Treg immunobiology in B-cell lymphoid malignancies, focusing on clinical correlations, mechanisms of accumulation, phenotype, and function. Overarching trends suggest that Tregs can be induced directly by tumor cells and recruited to the tumor microenvironment where they suppress antitumor immunity to facilitate disease progression. Further, we highlight studies showing that Tregs can be modulated by novel therapeutic agents such as immune checkpoint blockade and targeted therapies. Treg disruption by novel therapeutics may beneficially restore immune competence but has been associated with occurrence of adverse events. Strategies to achieve balance between these two outcomes will be paramount in the future to improve therapeutic efficacy and safety.

Immune Checkpoint Inhibitors in Peripheral T-Cell Lymphoma

Peripheral T-cell lymphomas (PTCLs) are highly heterogeneous and present significant treatment challenges. Immune checkpoint therapies, such as PD-1 and CTLA-4 inhibitors, have significantly changed the clinical management paradigm of tumors. The roles of immune checkpoints in PTCL and related agents have been actively explored over recent years. PD-1 and PD-L1 expression is detectable in both PTCL and immune cells within the tumor microenvironment and forms the basis for the exploration of antibodies targeting these proteins. Such antibodies are currently being investigated in clinical trials to guide individualized therapy. PD-1/PD-L1 inhibitors alone and in combination with chemotherapy, radiotherapy, or targeted therapy have shown broad clinical efficacy and improved the survival of cancer patients. Studies of other immune checkpoint proteins, such as CTLA-4, TIM-3, LAG-3, and TIGIT, are likely to provide potential novel targets for immunotherapy. Here, we review the role of and recent advances in immune checkpoint blockade in common subtypes of PTCL, focusing on the anti-tumor immune responses to PD-1/PD-L1 blockers.

Diffuse large B-cell lymphoma (DLBCL) is infiltrated with activated CD8+ T-cells despite immune checkpoint signaling

Background

B-cell non-Hodgkin lymphomas (NHL) are hematologic malignancies that arise in the lymph node. Despite this, the malignant cells are not cleared by the immune cells present. The failure of anti-tumor immunity may be due to immune checkpoints such as the PD-1/PDL-1 axis, which can cause T-cell exhaustion. Unfortunately, unlike Hodgkin lymphoma, checkpoint blockade in NHL has shown limited efficacy.

Methods

We performed an extensive functional analysis of malignant and non-malignant lymph nodes using high dimensional flow cytometry. We compared follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL), and lymph nodes harboring reactive hyperplasia (RH).

Results

We identified an expansion of CD8⁺PD1⁺ T-cells in the lymphomas relative to RH. Moreover, we demonstrate that these cells represent a mixture of activated and exhausted T-cells in FL. In contrast, these cells are nearly universally activated and functional in DLBCL. This is despite expression of counter-regulatory molecules such as PD-1, TIM-3, and CTLA-4, and the presence of regulatory T-cells.

Conclusion

These data may explain the failure of single-agent immune checkpoint inhibitors in the treatment of DLBCL. Accordingly, functional differences of CD8⁺ T-cells between FL and DLBCL may inform future therapeutic targeting strategies.

Genetic characteristics involving the PD-1/PD-L1/L2 and CD73/A2aR axes and the immunosuppressive microenvironment in DLBCL

Background

Targeting the PD-1/PD-L1/L2 (programmed cell death protein 1/programmed cell death ligand 1/ligand 2) pathway combined with other immunosuppressive signalings, such as CD73/A2aR (A2a adenosine receptor) adenosine signaling, has emerged as a promising strategy for cancer treatment. The genetic characteristics of these immune checkpoints need to be further investigated in diffuse large B-cell lymphoma (DLBCL).

Methods

We performed whole-exome sequencing/targeted deep sequencing to investigate the genetic characteristics of PD-1/PD-L1/L2 and CD73/A2aR. The immunosuppressive effect of these two pathways on the tumor microenvironment was evaluated via RNA sequencing. Single-cell RNA sequencing was further applied to investigate the dysfunctional CD8+ T cells. In addition, multiplex immunofluorescence staining was used to quantitatively assess the expression of dysfunctional CD8⁺ T cells in DLBCL.

Results

SP140 was identified as a novel translocation partner for PD-L1, and a new inversion was detected between PD-L1 and PD-L2, both leading to the upregulation of PD-L1 expression. CD73 genetic mutations did not increase mRNA and protein expression. Patients with genetically altered CD73 tended to have a better overall survival than patients with wild-type CD73. Both PD-1/PD-L1 and CD73/A2aR signaling mediated the immunosuppressive microenvironment in DLBCL. The numbers of CD8⁺ T cells with PD-1 and A2aR expression were positively correlated with the number of dysfunctional CD8⁺ T cells (R²=0.974, p=0.013). According to the grades of dysfunctional CD8⁺ T cells we defined, grade 1 dysfunctional CD8⁺ T cells, with either PD-1⁺ or A2aR⁺, were significantly associated with poorer survival than grade 0 dysfunctional CD8⁺ T cells, with both PD-1⁻ and A2aR⁻; and patients with grade 2 dysfunctional CD8⁺ T cells showed the worst clinical outcomes.

Conclusions

This study describes the additional genetic basis of PD-L1 overexpression and characterizes certain genetic alterations of CD73/A2aR in DLBCL. The degree of T-cell dysfunction is correlated with clinical outcomes. Strategies that reverse T-cell dysfunction by inhibiting PD-1/PD-L1/L2, particularly in combination with CD73/A2aR, may show potential as effective therapeutic options for DLBCL.

Epigenetic, Metabolic, and Immune Crosstalk in Germinal-Center-Derived B-Cell Lymphomas: Unveiling New Vulnerabilities for Rational Combination Therapies

B-cell non-Hodgkin lymphomas (B-NHLs) are highly heterogenous by genetic, phenotypic, and clinical appearance. Next-generation sequencing technologies and multi-dimensional data analyses have further refined the way these diseases can be more precisely classified by specific genomic, epigenomic, and transcriptomic characteristics. The molecular and genetic heterogeneity of B-NHLs may contribute to the poor outcome of some of these diseases, suggesting that more personalized precision-medicine approaches are needed for improved therapeutic efficacy. The germinal center (GC) B-cell like diffuse large B-cell lymphomas (GCB-DLBCLs) and follicular lymphomas (FLs) share specific epigenetic programs. These diseases often remain difficult to treat and surprisingly do not respond advanced immunotherapies, despite arising in secondary lymphoid organs at sites of antigen recognition. Epigenetic dysregulation is a hallmark of GCB-DLBCLs and FLs, with gain-of-function (GOF) mutations in the histone methyltransferase EZH2, loss-of-function (LOF) mutations in histone acetyl transferases CREBBP and EP300, and the histone methyltransferase KMT2D representing the most prevalent genetic lesions driving these diseases. These mutations have the common effect to disrupt the interactions between lymphoma cells and the immune microenvironment, via decreased antigen presentation and responsiveness to IFN-γ and CD40 signaling pathways. This indicates that immune evasion is a key step in GC B-cell lymphomagenesis. EZH2 inhibitors are now approved for the treatment of FL and selective HDAC3 inhibitors counteracting the effects of CREBBP LOF mutations are under development. These treatments can help restore the immune control of GCB lymphomas, and may represent optimal candidate agents for more effective combination with immunotherapies. Here, we review recent progress in understanding the impact of mutant chromatin modifiers on immune evasion in GCB lymphomas. We provide new insights on how the epigenetic program of these diseases may be regulated at the level of metabolism, discussing the role of metabolic intermediates as cofactors of epigenetic enzymes. In addition, lymphoma metabolic adaptation can negatively influence the immune microenvironment, further contributing to the development of immune cold tumors, poorly infiltrated by effector immune cells. Based on these findings, we discuss relevant candidate epigenetic/metabolic/immune targets for rational combination therapies to investigate as more effective precision-medicine approaches for GCB lymphomas.

Effect of TU-100 on Peyer's patches in a bacterial translocation rat model

BACKGROUND

Daikenchuto (TU-100), a Japanese herbal medicine, is widely used for various gastrointestinal diseases. We have previously reported that TU-100 suppresses CPT-11-induced bacterial translocation (BT) by maintaining the diversity of the microbiome. In this study we show that TU-100 modulates the immune response during BT by inducing PD-1 expression in Peyer's patches.

METHODS

Eighteen male Wistar rats were divided into four groups: a control group; a control + TU-100 group, given TU-100 1000 mg/kg orally for 5 d; a BT group, given CPT-11 250 mg/kg intra-peritoneal for 2 d; and a TU-100 group, given TU-100 1000 mg/kg orally for 5 d with CPT-11 250 mg/kg intra-peritoneal on days 4 and 5.

RESULTS

The size of Peyer's patch was significantly bigger in the BT group compared to the control group (9.0 × 104 µm2 vs 29.4 × 104 µm2, P < .05), but improved in the TU-100 group (15.4 × 104 µm2, P < .005). TU-100 significantly induced PD-1 expression in Peyer's patch compared to the control group and the BT group (control vs BT vs TU-100 = 4.3 ± 4.9 vs 5.1 ± 10.3 vs 17.9 ± 17.8). The CD4+ cells were increased in the BT group (P < .05) compared to the control group but decreased in the TU-100 group. The Foxp3+ cells were increased in the BT group compared to the control group (P < .05), and further increased in the TU-100 group compared to the BT group. CPT-11 significantly increased TLR4, NF-κβ, TNF-α mRNA expressions in the BT group. TU-100 cotreatment significantly reversed these mRNA expressions.

CONCLUSION

TU-100 may have a protective effect against BT through PD-1 expression in Peyer's patch.

EOMES and IL-10 regulate antitumor activity of T regulatory type 1 CD4+ T cells in chronic lymphocytic leukemia

The transcription factor eomesodermin (EOMES) promotes interleukin (IL)-10 expression in CD4+ T cells, which has been linked to immunosuppressive and cytotoxic activities. We detected cytotoxic, programmed cell death protein-1 (PD-1) and EOMES co-expressing CD4+ T cells in lymph nodes (LNs) of patients with chronic lymphocytic leukemia (CLL) or diffuse large B-cell lymphoma. Transcriptome and flow cytometry analyses revealed that EOMES does not only drive IL-10 expression, but rather controls a unique transcriptional signature in CD4+ T cells, that is enriched in genes typical for T regulatory type 1 (TR1) cells. The TR1 cell identity of these CD4+ T cells was supported by their expression of interferon gamma and IL-10, as well as inhibitory receptors including PD-1. TR1 cells with cytotoxic capacity accumulate also in Eµ-TCL1 mice that develop CLL-like disease. Whereas wild-type CD4+ T cells control TCL1 leukemia development after adoptive transfer in leukopenic Rag2-/- mice, EOMES-deficient CD4+ T cells failed to do so. We further show that TR1 cell-mediated control of TCL1 leukemia requires IL-10 receptor (IL-10R) signaling, as Il10rb-deficient CD4+ T cells showed impaired antileukemia activity. Altogether, our data demonstrate that EOMES is indispensable for the development of IL-10-expressing, cytotoxic TR1 cells, which accumulate in LNs of CLL patients and control TCL1 leukemia in mice in an IL-10R-dependent manner.

Immune-Checkpoint Inhibitors in B-Cell Lymphoma

Simple Summary

Immune-based treatment strategies, which include immune checkpoint inhibition, have recently become a new frontier for the treatment of B-cell-derived lymphoma. Whereas checkpoint inhibition has given oncologists and patients hope in specific lymphoma subtypes like Hodgkin lymphoma, other entities do not benefit from such promising agents. Understanding the factors that determine the efficacy and safety of checkpoint inhibition in different lymphoma subtypes can lead to improved therapeutic strategies, including combinations with various chemotherapies, biologics and/or different immunologic agents with manageable safety profiles.

Abstract

For years, immunotherapy has been considered a viable and attractive treatment option for patients with cancer. Among the immunotherapy arsenal, the targeting of intratumoral immune cells by immune-checkpoint inhibitory agents has recently revolutionised the treatment of several subtypes of tumours. These approaches, aimed at restoring an effective antitumour immunity, rapidly reached the market thanks to the simultaneous identification of inhibitory signals that dampen an effective antitumor response in a large variety of neoplastic cells and the clinical development of monoclonal antibodies targeting checkpoint receptors. Leading therapies in solid tumours are mainly focused on the cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed death 1 (PD-1) pathways. These approaches have found a promising testing ground in both Hodgkin lymphoma and non-Hodgkin lymphoma, mainly because, in these diseases, the malignant cells interact with the immune system and commonly provide signals that regulate immune function. Although several trials have already demonstrated evidence of therapeutic activity with some checkpoint inhibitors in lymphoma, many of the immunologic lessons learned from solid tumours may not directly translate to lymphoid malignancies. In this sense, the mechanisms of effective antitumor responses are different between the different lymphoma subtypes, while the reasons for this substantial difference remain partially unknown. This review will discuss the current advances of immune-checkpoint blockade therapies in B-cell lymphoma and build a projection of how the field may evolve in the near future. In particular, we will analyse the current strategies being evaluated both preclinically and clinically, with the aim of fostering the use of immune-checkpoint inhibitors in lymphoma, including combination approaches with chemotherapeutics, biological agents and/or different immunologic therapies.

Activating the Antitumor Immune Response in Non-Hodgkin Lymphoma Using Immune Checkpoint Inhibitors

Non-Hodgkin lymphomas comprise a heterogenous group of disorders which differ in biology. Although response rates are high in some groups, relapsed disease can be difficult to treat, and newer approaches are needed for this patient population. It is increasingly apparent that the immune system plays a significant role in the propagation and survival of malignant cells. Immune checkpoint blocking agents augment cytotoxic activity of the adaptive and innate immune systems and enhance tumor cell killing. Anti-PD-1 and anti-CTLA-4 antibodies have been tested as both single agents and combination therapy. Although success rates with anti-PD-1 antibodies are high in patients with Hodgkin lymphoma, the results are yet to be replicated in those with non-Hodgkin lymphomas. Some lymphoma histologies, such as primary mediastinal B cell lymphoma (PMBL), central nervous system, and testicular lymphomas and gray zone lymphoma, respond favorably to PD-1 blockade, but the response rates in most lymphoma subtypes are low. Other agents including those targeting the adaptive immune system such as TIM-3, TIGIT, and BTLA and innate immune system such as CD47 and KIR are therefore in trials to test alternative ways to activate the immune system. Patient selection based on tumor biology is likely to be a determining factor in treatment response in patients, and further research exploring optimal patient populations, newer targets, and combination therapy as well as identifying biomarkers is needed.

The tumor microenvironment of lymphomas: Insights into the potential role and modes of actions of checkpoint inhibitors

The tumor microenvironment (TME) - a term comprising non-neoplastic cells and extracellular matrix as well as various cytokines, chemokines, growth factors, and other substances in the vicinity of tumor cells - is an integrative part of most tumors including lymphomas. Interactions between lymphoma cells and the TME are vital for survival and proliferation of the former. In addition, lymphoma cells often reprogram the TME to protect them from defense mechanisms of the host's immune system. In this review, we will introduce the role of the tumor microenvironment (TME) for lymphoma cells looking at direct cell-cell interactions as well as cytokine-related communications. The immunomodulative/immunosuppressive role of the TME is more and more coming into the focus of potential new targeted therapies, and thus a special attention will be given to the interactions of immune checkpoints such as programed cell death protein 1 and L1 (PD-1/PD-L1), T-cell immunoglobulin and mucin-domain containing protein-3 (TIM-3), lymphocyte-activation gene 3 (LAG-3), and cytotoxic T-lymphocyte-associated protein-4 (CTLA4) with the TME, as well as their expression by both lymphoma cells and cells of the TME. Aspects of the TME will be discussed for indolent and aggressive B-cell lymphomas, Hodgkin lymphomas, and T-cell lymphomas. In addition, the potential influence of other immunomodulators such as lenalidomide will be briefly touched. The complex role of the TME is in the focus of new therapeutic options. In order to exploit its full therapeutic potential, however, a thorough understanding of TME biology and interaction between lymphoma cells and the TME, as well as the host's immune system and the TME is necessary.

The influence of programmed cell death ligand 2 (PD-L2) expression on survival outcome and tumor microenvironment in diffuse large B cell lymphoma

The frequency and significance of programmed cell death ligand (PD-L) 2 expression in diffuse large B cell lymphoma (DLBCL) remain undefined. We described the expression pattern of PD-L/PD-1 in 88 DLBCL patients using immunohistochemistry. The association between PD-L expression and clinical characteristics/outcomes were analyzed. PD-L1 and PD-L2 were expressed in 14.8% and 68.2% of DLBCL patients with median positivity on tumor cells of 100% and 90%, respectively. PD-1 on tumor-infiltrating lymphocytes (TILs) was expressed in 12.5% of patients. Interestingly, 45.5% of patients had PD-L2 expressing TILs which were significantly associated with bulky disease (p = .046) and elevated lactate dehydrogenase (p = .048). PD-L1 and/or PD-L2 expression on lymphoma cells was associated with inferior progression-free survival (Hazard ratio [HR] 2.20; 95% Confidence Interval [CI] 1.004-4.84, p = .049) and overall survival (HR 2.27; 95%CI 1.03-4.98, p = .042), using multivariate analysis. In summary, PD-L2 expression on DLBCL is common and, together with PD-L1, were related to poor outcomes.

Inflammatory Cells in Diffuse Large B Cell Lymphoma

Diffuse large B cell lymphoma (DLBCL), known as the most common non-Hodgkin lymphoma (NHL) subtype, is characterized by high clinical and biological heterogeneity. The tumor microenvironment (TME), in which the tumor cells reside, is crucial in the regulation of tumor initiation, progression, and metastasis, but it also has profound effects on therapeutic efficacy. The role of immune cells during DLBCL development is complex and involves reciprocal interactions between tumor cells, adaptive and innate immune cells, their soluble mediators and structural components present in the tumor microenvironment. Different immune cells are recruited into the tumor microenvironment and exert distinct effects on tumor progression and therapeutic outcomes. In this review, we focused on the role of macrophages, Neutrophils, T cells, natural killer cells and dendritic cells in the DLBCL microenvironment and their implication as target for DLBCL treatment. These new therapies, carried out by the induction of adaptive immunity through vaccination or passive of immunologic effectors delivery, enhance the ability of the immune system to react against the tumor antigens inducing the destruction of tumor cells.

Immunological microenvironment gene expression in patients with diffuse large B cell non Hodgkin lymphoma

Background

Non Hodgkin lymphoma (NHL) is one of the immune system cancers. The occurrence and progression of malignant lymphomas depends on cellular pathways deregulation. Understanding the relationship between the immune system at the genetic level and malignant transformation is critical to reach its etiology.

Objective

The aim of this work is to evaluate the expression of five immune related genes (PD-1, FOXP3, GrA, GrB and CD11c) in patients with diffuse large B cell non Hodgkin lymphoma (DLBCL).

Materials and methods

This study was conducted on fifty patients with DLBCL and fifty sex and age matched apparently healthy subjects. The participants were subjected to these laboratory investigations: complete blood count, serum lactate dehydrogenase and β2microglobulin (β₂M) levels and determination of PD-1, FOXP3, GrA, GrB and CD11c gene expressions.

Results

The results of this study revealed that PD-1, FOXP3, GrA, GrB and CD11c gene expressions were significantly increased in DLBCL patients.

Conclusion

Patients with DLBCL have variablePD-1, FOXP3,GrA, GrB and CD11cgene expressions levels, which are correlated with the overall survival (OS) indicating that they can be good predictors of outcome in these patients.

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

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

Prognostic and clinicopathological significance of PD-1/PD-L1 expression in the tumor microenvironment and neoplastic cells for lymphoma

BACKGROUND

Recently, unprecedented clinical efficacy was observed during treatment of many solid tumors because of the introduction of programmed cell death 1 (PD-1)/programmed cell death 1 ligand 1 (PD-L1) immune checkpoint inhibitors. Preliminary clinical data indicates that checkpoint inhibition also represents a promising therapeutic strategy for certain lymphoid malignancies. However, PD-1/PD-L1 expression levels on neoplastic cells and in the tumor microenvironment vary among subtypes and their prognostic implications remain uncertain.

MAIN BODY

Here, we review the clinicopathological significance of PD-1/PD-L1 expression in lymphomas. Increased infiltration of PD-1+ tumor-infiltrating lymphocytes (TILs) is a favorable prognostic factor in diffuse large B-cell lymphoma (DLBCL) but not in Hodgkin's lymphoma (HL). Higher numbers of PD-1+ TILs were observed in follicular lymphoma (FL) than in other subtypes of B-cell lymphoma; however, its prognostic significance remains controversial. Infiltration of PD-L1+ immune cells showed a trend toward better overall survival in nasal natural killer (NK)/T-cell lymphoma and adult T-cell leukemia/lymphoma, more likely to be classified as activated macrophages and dendritic cells in microenvironment but its biological effect is not clarified. Peripheral PD-1+ T cells could be detected in blood samples from DLBCL and chronic lymphocytic leukemia (CLL) and correlated with disease progression and poor prognosis. PD-1+ neoplastic T cells were more frequently observed in cutaneous T-cell lymphoma, including Sézary syndrome and mycosis fungoides, which may be involved in the progression of epithelial-derived T lymphoma. Studies on PD-L1 expression in neoplastic cells mostly focused on DLBCL. PD-L1+ neoplastic cells were observed only in a small subset of DLBCL, mainly associated with activated B cell (ABC) subtypes and Epstein-Barr virus (EBV) positivity; however, its prognostic role remains controversial. In either T or B lymphoma, elevated serum or plasma levels of soluble PD-L1 represent adverse prognostic factors. Notably, in clinical trials of classical HL, the frequency of 9p24.1 chromosome alterations increases the abundance of PD-1 ligand expression, appearing to predict responses to anti-PD-1/PD-L1 therapy. The cytogenetic alterations affecting chromosome 9p24.1 including the CIITA rearrangement were also frequently observed in certain specific subtypes of large B-cell lymphomas.

CONCLUSIONS

The clinical roles of PD-1/PD-L1 expression vary between subtypes of lymphoma. Future studies should delineate the prognostic and predictive roles of PD-1 and PD-L1 expression.

Clinicopathological evaluation of the programmed cell death 1 (PD1)/programmed cell death-ligand 1 (PD-L1) axis in post-transplant lymphoproliferative disorders: association with Epstein-Barr virus, PD-L1 copy number alterations, and outcome

AIMS

The clinical implications of the programmed cell death 1 (PD1)/programmed cell death-ligand 1 (PD-L1) axis in patients with post-transplant lymphoproliferative disorders are largely unknown, and its association with Epstein-Barr virus (EBV) status and PD-L1 copy number alterations (CNAs) has not been thoroughly studied.

METHODS AND RESULTS

PD1/PD-L1 expression was studied in 50 adult post-transplant lymphoproliferative disorders, and the correlations with PD-L1 CNAs, EBV, clinicopathological features and outcome were evaluated. Thirty-seven (74%) cases were classified as diffuse large B-cell lymphoma (DLBCL), nine (18%) cases were classified as polymorphic, and four (8%) cases were classified as classic Hodgkin lymphoma. Thirty-four cases were EBV-positive, with 29 of 34 (85%) having latency II or III, and 15 of 34 (44%) having viral replication. PD-L1 expression in tumour cells and tumour-associated macrophages was observed in 30 (60%) and 37 (74%) cases, respectively. PD1 positivity was seen in 16 (32%) cases. PD-L1 expression was associated with EBV with latency II or III (P = 0.001) and organ rejection (P = 0.04), and, in DLBCL, with non-germinal centre type DLBCL (P < 0.001). Cases with PD-L1-positive tumour cells showed a higher number of PD-L1 CNAs than PD-L1-negative cases (P = 0.001). Patients with EBV/latency III/replication and simultaneous PD-L1 expression showed the worst overall survival (P < 0.001).

CONCLUSIONS

The PD1/PD-L1 axis is deregulated in post-transplant lymphoproliferative disorders, with frequent PD-L1 expression and PD1 negativity. PD-L1 expression is associated with EBV latency II or III and PD-L1 CNAs, and probably reflects a proinflammatory tumour microenvironment. The combined analysis of EBV status and PD-L1 expression may help to identify deeply immunosuppressed patients who can benefit from immune reconstitution approaches.

Pembrolizumab for the treatment of diffuse large B-cell lymphoma

Introduction: Pembrolizumab is a novel monoclonal antibody that targets the interaction between programmed cell death protein 1 (PD-1) and its ligand (PD-L1). Pembrolizumab has shown significant clinical efficacy in Hodgkin Lymphoma (HL), but results in non Hodgkin Lymphoma (NHL) are mixed. Some NHL subtypes, which share certain genetic features with HL, such as alterations in chromosome 9p24.1 and expression of PD-L1, have shown promising responses in early phase trials. Areas covered: In this review, we provide an overview of pembrolizumab as a compound, and present the available clinical efficacy and safety data in the treatment of diffuse large B cell lymphomas. Expert opinion: Current early phase data suggest that single agent pembrolizumab in NHL demonstrates both efficacy and a favorable safety profile. However, it is anticipated that future treatment strategies will be biomarker-driven and incorporate pembrolizumab into combination therapies with chemotherapy and/or immunotherapy agents.

Targeting the Immune Microenvironment in Lymphomas of B-Cell Origin: From Biology to Clinical Application

In lymphomas of B-cell origin, cancer cells orchestrate an inflammatory microenvironment of immune and stromal cells that sustain the tumor cell survival and growth, known as a tumor microenvironment (TME). The features of the TME differ between the different lymphoma types, ranging from extremely inflammatory, such as in Hodgkin lymphoma, to anergic, leading to immune deficiency and susceptibility to infections, such as in chronic lymphocytic leukemia. Understanding the characteristic features of the TME as well as the interactions between cancer and TME cells has given insight into the pathogenesis of most lymphomas and contributed to identify novel therapeutic targets. Here, we summarize the preclinical data that contributed to clarifying the role of the immune cells in the TME of different types of lymphomas of B-cell origin, and explain how the understanding of the biological background has led to new clinical applications. Moreover, we provide an overview of the clinical results of trials that assessed the safety and efficacy of drugs directly targeting TME immune cells in lymphoma patients.

PD-1/PD-L1 expression and interaction by automated quantitative immunofluorescent analysis show adverse prognostic impact in patients with diffuse large B-cell lymphoma having T-cell infiltration: a study from the International DLBCL Consortium Program

Programmed cell death protein 1/programmed cell death protein ligand1 (PD-1/PD-L1) interaction is an important immune checkpoint targeted by anti-PD-1/PD-L1 immunotherapies. However, the observed prognostic significance of PD-1/PD-L1 expression in diffuse large B-cell lymphoma treated with the standard of care has been inconsistent and even contradictory. To clarify the prognostic role of PD-1/PD-L1 expression and interaction in diffuse large B-cell lymphoma, in this study we used 3-marker fluorescent multiplex immunohistochemistry and Automated Quantitative Analysis Technology to assess the CD3⁺, PD-L1⁺, and PD-1⁺CD3⁺ expression in diagnostic samples and PD-1/PD-L1 interaction as indicated by presence of PD-1⁺CD3⁺ cells in the vicinity of PD-L1⁺ cells, analyzed their prognostic effects in 414 patients with de novo diffuse large B-cell lymphoma, and examined whether PD-1/PD-L1 interaction is required for the prognostic role of PD-1⁺/PD-L1⁺ expression. We found that low T-cell tissue cellularity, tissue PD-L1⁺ expression (irrespective of cell types), PD-1⁺CD3⁺ expression, and PD-1/PD-L1 interaction showed hierarchical adverse prognostic effects in the study cohort. PD-1/PD-L1 interaction showed higher sensitivity and specificity than PD-1⁺ and PD-L1⁺ expression in predicting inferior prognosis in patients with high CD3⁺ tissue cellularity ("hot"/inflammatory tumors). However, both PD-1⁺ and PD-L1⁺ expression showed adverse prognostic effects independent of PD-1/PD-L1 interaction, and PD-1/PD-L1 interaction showed favorable prognostic effect in PD-L1⁺ patients without high CD3⁺ tissue cellularity. Macrophage function and tumor-cell MYC expression may contribute to the PD-1-independent adverse prognostic effect of PD-L1⁺ expression. In summary, low T-cell tissue cellularity has unfavorable prognostic impact in diffuse large B-cell lymphoma, and tissue PD-L1⁺ expression and T-cell-derived PD-1⁺ expression have significant adverse impact only in patients with high T-cell infiltration. PD-1/PD-L1 interaction in tissue is essential but not always responsible for the inhibitory effect of PD-L1⁺/PD-1⁺ expression. These results suggest the benefit of PD-1/PD-L1 blockade therapies only in patients with sufficient T-cell infiltration, and the potential of immunofluorescent assays and Automated Quantitative Analysis in the clinical assessment of PD-1/PD-L1 expression and interaction.

Safety and Efficacy of Anti-PD-1 Monoclonal Antibodies in Patients With Relapsed or Refractory Lymphoma: A Meta-Analysis of Prospective Clinic Trails

Background: Immune checkpoint inhibition therapy with monoclonal antibody against programmed cell death protein 1 (PD-1), including nivolumab and pembrolizumab, has demonstrated powerful clinical efficacy in the treatment of advanced cancers. However, there is no evidence-based systematic review on the safety and efficacy of anti-PD-1 antibody in treating lymphoma.

Methods: To evaluate the safety and efficacy of nivolumab/pembrolizumab, we analyzed clinical trials from PUBMED, EMBASE, and The Cochrane Library. For safety analysis, the incidence and exhibition of any grade and grade ≥3 adverse events (AEs) were evaluated. Overall response rate (ORR), 6-month progression-free survival (PFS) and 6-month overall survival (OS) were calculated for efficacy analysis.

Results: Overall ten studies and 718 patients (114 non-Hodgkin lymphomas, 604 Hodgkin lymphomas) were enrolled, including 4 phase I studies and 6 phase II studies. The pooled incidences of any grade and grade ≥3 adverse events (AEs) were 74 and 24%, respectively. Drug-related deaths occurred in two patients. The most common any grade AEs were fatigue (14.91%), rash (14.8%), hypothyroidism (13.77%), platelet count decreased (13.54%), pyrexia (13%). The most common grade ≥3 AEs were neutropenia (4.79%), pneumonitis (3.58%), rash (3.38%), and leukopenia (3.31%). Fatigue (p = 0.0072) and rash (p = 0.0078) in any grade AEs were less observed in patients treated with pembrolizumab than nivolumab. The pooled ORR, PFS rate and OS rate were 58, 73, and 96%, respectively. The ORR in patients with Hodgkin lymphomas (HL) was higher than patients with non-Hodgkin lymphomas (NHL) (69.08 vs. 30.77%, p < 0.0001). However, there was no significant difference of efficacy between nivolumab and pembrolizumab.

Conclusions: Nivolumab and pembrolizumab have promising outcomes with tolerable AEs and drug-related deaths in patients with relapsed or refractory lymphoma. Pembrolizumab caused less any grade AEs like fatigue and rash than nivolumab. Patients with HL got better response than NHL.

Understanding Immune Evasion and Therapeutic Targeting Associated with PD-1/PD-L1 Pathway in Diffuse Large B-cell Lymphoma

In tumor microenvironment, the programmed death 1 (PD-1) immune checkpoint has a crucial role of mechanism of T cell exhaustion leading to tumor evasion. Ligands of PD-1, programmed death ligand 1/2 (PD-L1/L2) are over-expressed in tumor cells and participate in prolonged tumor progression and survivals. Recently, clinical trials for patients who failed to obtain an optimal response prior to standardized chemotherapy in several solid cancers have been focused on targeting therapy against PD-1 to reduce disease progression rates and prolonged survivals. Since various inhibitors targeting the immune checkpoint in PD-1/PD-L1 pathway in solid cancers have been introduced, promising approach using anti-PD-1 antibodies were attempted in several types of hematologic malignances. In diffuse large B cell lymphoma (DLBCL) as the most common and aggressive B cell type of non-Hodgkin’s lymphoma, anti-PD-1 and anti-PD-L1 antibodies were studies in various clinical trials. In this review, we summarized the results of several studies associated with PD-1/PD-L1 pathway as an immune evasion mechanism and described clinical trials about targeting therapy against PD-1/PD-L1 pathway in DLBCL.

The immune checkpoint molecules PD-1, PD-L1, TIM-3 and LAG-3 in diffuse large B-cell lymphoma

Signaling through immune checkpoint receptors may lead to T-cell exhaustion and function as immune escape mechanisms in cancer. For diffuse large B-cell lymphoma (DLBCL), the mechanistic and prognostic importance of these markers on tumor cells and the tumor microenvironment remains unclear. We determined the immunohistochemical expression of PD-1, PD-L1, TIM-3, and LAG-3 on tumor cells and on tumor infiltrating lymphocytes (TILs) among 123 DLBCL patients. TIM-3 showed positive staining on tumor cells in 39% of DLBCL cases and PD-L1 expression was noted in 15% of cases. Both PD-1 and LAG-3 were positive on tumor cells in a minority of DLBCL cases (8.3% and 7.5%, respectively), but were more widely expressed on TILs in a correlated manner. With median follow-up of 44 months (n = 70, range 5-85), 4-year progression-free survival (PFS) and overall survival (OS) rates were significantly inferior among DLBCL patients with high vs low/negative TIM-3 expression (PFS: 23% [95% CI 7% to 46%] vs 60% [95% CI 43% to 74%], respectively, P = 0.008; OS: 30% [95% CI 10% to 53%] vs 74% [95% CI 58% to 85%], respectively, P = 0.006). Differences in OS remained significant when controlling for International Prognostic Index in Cox regression analyses (HR 3.49 [95% CI 1.40-6.15], P = 0.007). In addition, we observed that co-culture of DLBCL cell lines with primed T cells in the presence of anti-LAG-3 and anti-TIM-3 induced potent dose-dependent increases in in vitro cell death via AcellaTox and IL-2 ELISA assays, suggesting potent anti-tumor activity of these compounds.

Programmed cell death protein receptor and ligands in haematological malignancies - Current status

The checkpoint inhibitors have been continuously present in haematology for 20 years. From the first description, several of them were enrolled to the list of the oncological drugs. The research on nivolumab, avelumab, durvolumab is still in progress. In the treatment of some diseases, for instance, Hodgkin lymphoma, the programmed death cell pathway has already an important role. During the last years, the guidelines were enriched by using these drugs, both in solid and haematological malignancies. In this review, we present a history of discovery, research and clinical use of this new class of drugs potentially providing a significant change in curability rates of some haematological malignancies.

PD1hi cells associate with clusters of proliferating B-cells in marginal zone lymphoma

Background

Abnormally sustained immune reactions drive B-cell proliferation in some cases of marginal zone lymphoma but the CD4⁺ T-cell subsets, which are likely to contribute to the B-cell responses in the tumour microenvironment, are not well characterised and neither has the spatial distribution of the different subsets in involved lymph nodes been investigated.

Methods

Employing a workflow of multiplex semi-automated immunohistochemistry combined with image processing we investigated association between infiltrating T-cells and proliferating lymphoma B-cells.

Results

Both total numbers of activating follicular helper (Tfh) cells (defined by high expression of PD1) and suppressive regulatory (Treg) T-cells (defined by FOXP3⁺ expression) and the Tfh:Treg ratio, assessed over relatively large areas of tissue, varied among cases of marginal zone lymphoma. We determined spatial distribution and demonstrated that PD1^hi cells showed significantly more clustering than did FOXP3⁺. To investigate the association of infiltrating T-cells with lymphoma B-cells we employed Pearson correlation and Morisita-Horn index, statistical measures of interaction. We demonstrated that PD1^hi cells were associated with proliferating B-cells and confirmed this by nearest neighbour analysis.

Conclusions

The unexpected architectural complexity of T-cell infiltration in marginal zone lymphoma, revealed in this study, further supports a key role for Tfh cells in driving proliferation of lymphoma B-cells. We demonstrate the feasibility of digital analysis of spatial architecture of T-cells within marginal zone lymphoma and future studies will be needed to determine the clinical importance of these observations.

Intratumoral FOXP3+ Regulatory T Cells in Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma in Egypt and worldwide. Gene expression profiling classifies DLBCL into: germinal center B cell-like (GCB) and non germinal center B cell-like (non-GCB) DLBCL. Hans' algorithm has high concordance with gene expression profiling results. Regulatory T cells (Tregs) represent important modulators for the interaction between lymphoma cells and host microenvironment. FOXP3 is a popular single marker for Tregs. There is little information about the possible role of Tregs in high-grade lymphoma such as DLBCL. This study aims to assess the prognostic impact of FOXP3+ Tregs in DLBCL. The study was carried out on 70 archival cases (61 de novo DLBCL and 9 reactive follicular hyperplasia cases). DLBCL cases were classified into GCB and non-GCB groups using Hans' algorithm. All studied cases are subjected to FOXP3 immunostaining. Density of FOXP3+ Tregs was higher in reactive cases compared with DLBCL (P=0.000). In DLBCL cases, FOXP3 expression was associated with free spleen (P=0.02), early stage (P=0.05), centroblastic variant (P=0.003), and absence of necrosis (P=0.05). In germinal cases, density of FOXP3 was significantly higher in cases with good PS (P=0.02), very good and good revised international prognostic index (P=0.002), and low-risk age-adjusted international prognostic index >60 (P=0.01). Non germinal DLBCL cases with negative FOXP3 were significantly associated with splenic involvement (P=0.005). DLBCL cases with high FOXP3 have longer survival (P=0.03). T cells in the background of DLBCL may play a role in modulation of tumor progression. Their presence is associated with favorable prognostic parameters in DLBCL.

MicroRNA signatures and Foxp3+ cell count correlate with relapse occurrence in follicular lymphoma

First line drug treatment of follicular lymphoma (FL) patients is followed by a highly variable disease-free time before relapse in about one third of patients. No molecular marker is able to predict efficiently the risk of relapse. We investigated the expression profile of microRNAs (miRNAs) by microarrays and of the tumor microenvironment by immunohistochemistry in 26 FLs and 12 reactive lymph nodes (rLN) as reference. Twenty-nine miRNAs were differentially expressed in FLs compared to rLNs and some of them discriminated grade 1 from 3a FLs. Both FLs and rLNs displayed molecular heterogeneity. FLs grouped into two clusters mostly driven by the tumor T-cell content. Among 21 drug-treated FL patients with an average follow-up of 13.5 years, eight cases relapsed. Twenty-six miRNAs discriminated between relapsed and non-relapsed FLs. Ten miRNAs also correlated with Foxp3⁺ cells number. Notably, Foxp3⁺ cells were significantly less in relapsed patients and lower Foxp3⁺ cell number associated with shorter time-to-relapse. Foxp3⁺ cells did not co-expressed follicular helper T-cell markers and were therefore classified as regulatory T cells rather than follicular regulatory T-cells. These findings introduce new knowledge about the relationship between miRNA alterations and infiltrating immune cells and show that Foxp3⁺ cells might be predictive of disease relapse.

Mechanisms of PD-1/PD-L1 expression and prognostic relevance in non-Hodgkin lymphoma: a summary of immunohistochemical studies

Immune checkpoint blockade therapeutics, notably antibodies targeting the programmed death 1 (PD-1) receptor and its PD-L1 and PD-L2 ligands, are currently revolutionizing the treatment of cancer. For a sizeable fraction of patients with melanoma, lung, kidney and several other solid cancers, monoclonal antibodies that neutralize the interactions of the PD-1/PD-L1 complex allow the reconstitution of long-lasting antitumor immunity. In hematological malignancies this novel therapeutic strategy is far less documented, although promising clinical responses have been seen in refractory and relapsed Hodgkin lymphoma patients. This review describes our current knowledge of PD-1 and PD-L1 expression, as reported by immunohistochemical staining in both non-Hodgkin lymphoma cells and their surrounding immune cells. Here, we discuss the multiple intrinsic and extrinsic mechanisms by which both T and B cell lymphomas up-regulate the PD-1/PD-L1 axis, and review current knowledge about the prognostic significance of its immunohistochemical detection. This body of literature establishes the cell surface expression of PD-1/PD-L1 as a critical determinant for the identification of non-Hodgkin lymphoma patients eligible for immune checkpoint blockade therapies.

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.

Prognostic implications of tumor-infiltrating macrophages, M2 macrophages, regulatory T-cells, and indoleamine 2,3-dioxygenase-positive cells in primary diffuse large B-cell lymphoma of the central nervous system

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

Lymphocyte-to-monocyte ratio is associated with prognosis of diffuse large B-cell lymphoma: correlation with CD163 positive M2 type tumor-associated macrophages, not PD-1 positive tumor-infiltrating lymphocytes

The research aims to examine the prognostic value of the lymphocyte-to-monocyte ratio (LMR), neutrophil-to- lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in diffuse large B-cell lymphoma (DLBCL). The relation of these hematologic indicators to poor antitumor immunity and prognosis must be investigated. Clinicopathologic data and survival information of 355 patients with DLBCL was retrospectively analyzed. Univariate analysis revealed that lower LMR (<2.71), higher NLR (≥2.81), CD163+ M2 tumor-associated macrophages (TAM) content ≥9.5% and programmed cell death 1 (PD-1)+ tumor-infiltrating lymphocytes (TILs) content < 4.5 cells per high power field(HPF) were significantly related to unfavorable overall survival (OS) and progression free survival (PFS). When considering the prognostic indexes of IPI, multivariate analysis confirmed that LMR of <2.71 and CD163⁺ M2 TAM content ≥9.5% significantly affected the prognosis of DLBCL. Spearman correlation test showed LMR was negatively correlated with CD163⁺ M2 TAM content. However, there were no correlation was found between LMR and PD-1+ TIL as well as between NLR and PD-1+ TIL content. These results indicated that decreased LMR lead to a weak anti-tumor immunity and could be used as a bad prognosis biomarker of DLBCL.

PD-1 /PD-L1 checkpoint in hematological malignancies

Programmed cell death protein 1 (PD-1), is a cell surface receptor with an important role in down-regulating the immune system and promoting self-tolerance by suppressing T cell inflammatory activity. PD-1/PDL1 axis represents a checkpoint to control immune responses and it is often used as a mechanism of immune escaping by cancers and infectious diseases. Many data demonstrate its important role in solid tumors and report emerging evidences in lymphoproliferative disorders. In this review, we summarized the available data on the role of PD-1/PD-L1 checkpoint in lymphoproliferative diseases and the therapeutics use of monoclonal blocking antibodies.

PD-1 expression and clinical PD-1 blockade in B-cell lymphomas

Programmed cell death protein 1 (PD-1) blockade targeting the PD-1 immune checkpoint has demonstrated unprecedented clinical efficacy in the treatment of advanced cancers including hematologic malignancies. This article reviews the landscape of PD-1/programmed death-ligand 1 (PD-L1) expression and current PD-1 blockade immunotherapy trials in B-cell lymphomas. Most notably, in relapsed/refractory classical Hodgkin lymphoma, which frequently has increased PD-1+ tumor-infiltrating T cells, 9p24.1 genetic alteration, and high PD-L1 expression, anti-PD-1 monotherapy has demonstrated remarkable objective response rates (ORRs) of 65% to 87% and durable disease control in phase 1/2 clinical trials. The median duration of response was 16 months in a phase 2 trial. PD-1 blockade has also shown promise in a phase 1 trial of nivolumab in relapsed/refractory B-cell non-Hodgkin lymphomas, including follicular lymphoma, which often displays abundant PD-1 expression on intratumoral T cells, and diffuse large B-cell lymphoma, which variably expresses PD-1 and PD-L1. In primary mediastinal large B-cell lymphoma, which frequently has 9p24.1 alterations, the ORR was 35% in a phase 2 trial of pembrolizumab. In contrast, the ORR with pembrolizumab was 0% in relapsed chronic lymphocytic leukemia (CLL) and 44% in CLL with Richter transformation in a phase 2 trial. T cells from CLL patients have elevated PD-1 expression; CLL PD-1+ T cells can exhibit a pseudo-exhaustion or a replicative senescence phenotype. PD-1 expression was also found in marginal zone lymphoma but not in mantle cell lymphoma, although currently anti-PD-1 clinical trial data are not available. Mechanisms and predictive biomarkers for PD-1 blockade immunotherapy, treatment-related adverse events, hyperprogression, and combination therapies are discussed in the context of B-cell lymphomas.

Tailoring front-line therapy in diffuse large B-cell lymphoma: who should we treat differently?

Although there have been significant insights into the biology of diffuse large B-cell lymphoma (DLBCL) over recent years, progress in our therapeutic approach has been disappointing over the same timeframe. This is not for want of trying. In 2017, R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone) remains the "gold standard," despite all of our insights into cell-of-origin and other subgroups. We have traditionally used clinical risk factors to tailor our therapies and have tested intensification of chemotherapy with little success. We are now in an era of testing therapies according to the molecular phenotype of the individual's tumor. Many phase 1/2 studies have looked at adding targeted agents to conventional R-CHOP with some promise. The phase 3 data are now starting to emerge. Are we ready yet to modify our standard of care and have we reached an era of precision medicine in DLBCL? The answer to this is "not yet." The exception is perhaps patients with the newly defined World Health Organization category of high-grade B-cell lymphoma with rearrangements of MYC and BCL2 and/or BCL6, the so-called double- and triple-hit lymphomas. In these tumors there has been a move away from R-CHOP to more intensified regimens, however, has not been based upon rigorous prospective evaluation but review of retrospective datasets. This article will review the molecular subgroups of DLBCL, interventional strategies, and the outcomes of these interventions to date.

Cytotoxic response against Epstein Barr virus coexists with diffuse large B-cell lymphoma tolerogenic microenvironment: clinical features and survival impact

Epstein-Barr Virus (EBV) is present in neoplastic cells of 15% of Asian and Latin-American diffuse large B-cell lymphoma (DLBCL) patients. Even though a tolerogenic microenvironment was recently described in DLBCL, little is known concerning immunomodulatory features induced by EBV. As suggested in Hodgkin lymphoma, EBV-specific cytotoxic T-cells are increased but showing immune exhaustion features. Hence, host immunity suppression may play a critical role in tumor progression. This study aimed to investigate, whether an association between tumor microenvironment features and EBV presence is taking place, and its clinical correlate. The incidence of EBV+DLBCL NOS was 12.6% in this cohort. Cytokine and chemokine transcripts expression and immunophenotype analysis showed that EBV infection was associated with increased gene expression of immunosuppressive cytokine (IL-10) together with increased CD8+ T-cells and granzyme B+ cytotoxic effector cells. However, this specific response coexists with a tolerogenic milieu, by PD-1 expression, in EBV+ and EBV-DLBCL cases. High PD-1+ cell counts, EBV presence and low CCL22 expression were associated with worse survival, supporting our hypothesis that EBV-specific response is mounted locally and its inhibition by, for example PD-1+ cells, may negatively affect outcome. The better understanding of the interplay between lymphoma cells and microenvironment in a viral framework could thereby facilitate the discovery of new targets for innovative anti-lymphoma treatment strategies.

Catching up with solid tumor oncology: what is the evidence for a prognostic role of programmed cell death-ligand 1/programmed cell death-1 expression in B-cell lymphomas?

Therapeutic strategies targeting the programmed cell death-ligand 1/programmed cell death-1 pathway have shown significant responses and good tolerability in solid malignancies. Although preclinical studies suggest that inhibiting programmed cell death-ligand 1/programmed cell death-1 interactions might also be highly effective in hematological malignancies, remarkably few clinical trials have been published. Determining patients who will benefit most from programmed cell death-ligand 1/programmed cell death-1-directed immunotherapy and whether programmed cell death-ligand 1/programmed cell death-1 are adequate prognostic markers becomes an increasingly important clinical question, especially as aberrant programmed cell death-ligand 1/programmed cell death-1 expression are key mediators of impaired anti-tumor immune responses in a range of B-cell lymphomas. Herein, we systematically review the published literature on the expression and prognostic value of programmed cell death-ligand 1/programmed cell death-1 in these patients and identify considerable differences in expression patterns, distribution and numbers of programmed cell death-ligand 1⁺/programmed cell death-1⁺cells, both between and within lymphoma subtypes, which is reflected in conflicting findings regarding the prognostic value of programmed cell death-ligand 1⁺/programmed cell death-1⁺ cells. This can be partly explained by differences in methodologies (techniques, protocols, cutoff values) and definitions of positivity. Moreover, lymphomagenesis, disease progression, and prognosis appear to be determined not only by the presence, numbers and distribution of specific subtypes of T cells, but also by other cells and additional immune checkpoints. Collectively, our findings indicate that programmed cell death-ligand 1/programmed cell death-1 interactions play an essential role in B-cell lymphoma biology and are of clinical importance, but that the overall outcome is determined by additional components. To categorize the exact prognostic value of programmed cell death-ligand 1/programmed cell death-1 expressing cells and cell types, efforts should be made to harmonize their assessment and interpretation, optimally within ongoing clinical immune checkpoint inhibitor trials, and to identify and validate novel high-throughput platforms.

The expression and clinical relevance of PD-1, PD-L1, and TP63 in patients with diffuse large B-cell lymphoma

Latest study showed that a novel translocation between programmed cell death ligand 1 (PD-L1) (cluster of differentiation 274) and TP63 (tumor protein 63) can be found in diffuse large B-cell lymphoma (DLBCL), resulting in their conjunct overexpression in tumor cells at RNA level. However, the expressed pattern of these 2 genes at protein level in DLBCL remains largely unknown, and the clinical relevance of PD-L1 and TP63 expression in DLBCL are also unclear.Tumor tissues from 76 Chinese DLBCL patients were immunostained for programmed cell death 1 (PD-1), PD-L1, and TP63 using the EnVision system. Clinical relevance of PD-1, PD-L1, and TP63 in 74 DLBCL were analyzed by chi-square test, the Kaplan-Meier curves with log rank test, and Cox's proportional hazards regression model.PD-1 was mainly expressed in tumor-infiltrating lymphocytes (TILs) of 39.5% patients. PD-L1 was expressed in tumor cells of 26.3% patients, and TP63 was immunostained in nucleoli of tumor cells of 31.6% cases. PD-1 expression was significantly associated with the patients' gender and B symptoms (P = 0.032, P = 0.026). DLBCL with PD-L1 or TP63 expression in tumor cells showed low International Prognostic Index (IPI) score (P = 0.007, P = 0.009). PD-1 TILs was related to prolonged overall survival rate (OS) of DLBCL patients (P = 0.02), whereas PD-L1 expression was associated with worse clinical outcome of patients (P = 0.049). Immunoreactivity of TP63 was not correlated with patients' survival time. Besides, PD-1 expression, patients' age, Ann Arbor stage, and IPI score were significant prognostic markers for OS, but PD-L1 and TP63 had no prognostic significance.PD-1, PD-L1, and TP63 are frequently expressed in DLBCL. PD-1/PD-L1/TP63 blockade may be a potential therapeutic strategy for some patients.

[Immune-checkpoint and hemopathies]

Immune-checkpoint inhibitors represent potent new therapies for most lymphomas, particularly for refractory diseases. Contrasting with solid tumors the majority of lymphoma are sensitive to conventional therapies and immunotherapies such as anti-CD20 or anti-CD30. But relapsing lymphoma or refractory disease have a very poor prognosis and new drugs are mandatory. Immune-checkpoint inhibitors targeting CTLA4, PD-1 et PD-L1 demonstrated efficiency with prolonged survivals even after bone marrow allograft for aggressive disease. Lymphomas differ from solid tumors as tumor cells belong to the immune compartment and therefore molecules targeting immune cells may act on both immune environment and tumor cells. Furthermore, PD-L1 expression in most lymphomas is related to tumor cell molecular alterations such as PD-L1 gene amplification or mutation. PD-L1 protein expression on tumor cells and immune cells, particularly it frequency and distribution vary according to different lymphoma subtype and it may help to assess diagnosis as it may predict therapeutical response.

PD-1-PD-L1 immune-checkpoint blockade in B-cell lymphomas

Cancer cells can escape T-cell-mediated cellular cytotoxicity by exploiting the inhibitory programmed cell-death protein 1 (PD-1)/programmed cell death 1 ligand 1 (PD-L1) immune checkpoint. Indeed, therapeutic antibodies that block the PD-1-PD-L1 axis induce durable clinical responses against a growing list of solid tumours. B-cell lymphomas also leverage this checkpoint to escape immune recognition, although the outcomes of PD-1-PD-L1 blockade, and the correlations between PD-L1 expression and treatment responses, are less-well elucidated in these diseases than in solid cancers. Nevertheless, in patients with Hodgkin lymphoma, amplification of the gene encoding PD-L1 is commonly associated with increased expression of this protein on Reed-Sternberg cells. Correspondingly, PD-1 blockade with nivolumab has been demonstrated to result in response rates as high as 87% in unselected patients with relapsed and/or refractory Hodgkin lymphoma, leading to the FDA approval of nivolumab for this indication in May 2016. The PD-1/PD-L1 axis is probably also important for immune evasion of B-cell lymphomas with a viral aetiology, including those associated with human immunodeficiency virus (HIV) and Epstein-Barr virus (EBV). This Review is focused on the role of PD-1-PD-L1 blockade in unleashing host antitumour immune responses against various B-cell lymphomas, and summarizes the clinical studies of this approach performed to date.