A unifying microenvironment model in follicular lymphoma: outcome is predicted by programmed death-1--positive, regulatory, cytotoxic, and helper T cells and macrophages

Impact of positive CD4 cells on event-free survival in follicular lymphoma patients

OBJECTIVE

Previous results about prognostic value of CD4+ T cells in follicular lymphoma (FL) remain controversial.

METHODS

Immunohistochemistry was used to examine expression of positive CD4 cells in 103 patients with FL 1-3A. Early failure was described as failing to achieve event-free survival (EFS) at 12 or 24 months.

RESULTS

There were 49 (47.6%) male and 54 (52.4%) females, with a median age of 54 years. Compared to patients with <20% of positive CD4 cells, patients with ≥20% of positive CD4 cells exhibited a significant lower risk of early failure (2-year EFS rate: 56.7% vs 73.5%, p = 0.047). When patients were stratified based on positive CD4 cell combined with FLIPI, the median EFS (p = 0.002) and median OS (p = 0.007) were significantly different.

CONCLUSIONS

This study demonstrated that higher expression of positive CD4 cells predicts lower risk of early failure in follicular lymphoma, and combination analysis of CD4 and FLIPI could better predict disease relapse and survival outcome.

Proteomics identifies apoptotic markers as predictors of histological transformation in patients with follicular lymphoma

Follicular lymphoma (FL) is an indolent lymphoma with a generally favorable prognosis. However, histological transformation (HT) to a more aggressive disease leads to markedly inferior outcomes. This study aims to identify biological differences predictive of HT at the time of initial FL diagnosis. We show differential protein expression between diagnostic lymphoma samples from patients with subsequent HT (subsequently-transforming FL [st-FL]; n = 20) and patients without HT (nontransforming FL [nt-FL]; n = 34) by label-free quantification nano liquid chromatography-tandem mass spectrometry analysis. Protein profiles identified patients with high risk of HT. This was accompanied by disturbances in cellular pathways influencing apoptosis, the cytoskeleton, cell cycle, and immune processes. Comparisons between diagnostic st-FL samples and paired transformed FL (n = 20) samples demonstrated differential protein profiles and disrupted cellular pathways, indicating striking biological differences from the time of diagnosis up to HT. Immunohistochemical analysis of apoptotic proteins, CASP3, MCL1, BAX, BCL-xL, and BCL-rambo, confirmed higher expression levels in st-FL than in nt-FL samples (P < .001, P = .015, P = .003, P = .025, and P = .057, respectively). Moreover, all 5 markers were associated with shorter transformation-free survival (TFS; P < .001, P = .002, P < .001, P = .069, and P = .010, respectively). Notably, combining the expression of these proteins in a risk score revealed increasingly inferior TFS with an increasing number of positive markers. In conclusion, proteomics identified altered protein expression profiles (particularly apoptotic proteins) at the time of FL diagnosis, which predicted later transformation.

Advances in Monitoring and Prognostication for Lymphoma by Flow Cytometry

Flow cytometry (FC) is a well-established method important in the diagnosis and subclassification of lymphoma. In this article, the role of FC in lymphoma prognostication will be explored, and the clinical role for FC minimal/measurable residual disease testing as a monitoring tool for mature lymphoma will be introduced. Potential pitfalls of monitoring for residual/recurrent disease following immunotherapy will be presented.

Insights into the tumor microenvironment of B cell lymphoma

The standard therapies in lymphoma have predominantly focused on targeting tumor cells with less of a focus on the tumor microenvironment (TME), which plays a critical role in favoring tumor growth and survival. Such an approach may result in increasingly refractory disease with progressively reduced responses to subsequent treatments. To overcome this hurdle, targeting the TME has emerged as a new therapeutic strategy. The TME consists of T and B lymphocytes, tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), cancer-associated fibroblasts (CAFs), and other components. Understanding the TME can lead to a comprehensive approach to managing lymphoma, resulting in therapeutic strategies that target not only cancer cells, but also the supportive environment and thereby ultimately improve survival of lymphoma patients. Here, we review the normal function of different components of the TME, the impact of their aberrant behavior in B cell lymphoma and the current TME-direct therapeutic avenues.

Phenotype, Function, and Clinical Significance of CD26+ and CD161+Tregs in Splenic Marginal Zone Lymphoma

PURPOSE

Regulatory T-cells (Treg) are essential to Tregs homeostasis and modulate the antitumor immune response in patients with lymphoma. However, the biology and prognostic impact of Tregs in splenic marginal zone lymphoma (SMZL) have not been studied.

EXPERIMENTAL DESIGN

Biopsy specimens from 24 patients with SMZL and 12 reactive spleens (rSP) from individuals without lymphoma were analyzed by using CITE-seq (cellular indexing of transcriptomes and epitopes by sequencing), CyTOF (mass cytometry) analysis, and flow cytometry to explore the phenotype, transcriptomic profile, and clinical significance of intratumoral Tregs and their subsets. The biological characteristics and cell signaling pathways of intratumoral Treg subsets were confirmed by in vitro functional assays.

RESULTS

We found that Tregs are more abundant in SMZL patients' spleens than rSP, and Tregs from patients with SMZL and rSP can be separated into CD161+Treg and CD26+Treg subsets. CD161+Tregs are increased in SMZL but have dysregulated immune function. We found that CD161+Treg and CD26+Tregs have unique gene expression and phenotypic profiles and are differentially correlated with patient outcomes. Specifically, increased CD161+Tregs are significantly associated with a favorable prognosis in patients with SMZL, whereas CD26+Tregs are associated with a poor prognosis. Furthermore, activation of the IL2/STAT5 pathway contributes to the induction of CD26+Tregs and can be reversed by STAT5 inhibition.

CONCLUSIONS

IL2/STAT5-mediated expansion of CD26+Tregs contributes to a poor clinical outcome in SMZL and may represent a therapeutic opportunity in this disease.

High inter-follicular spatial co-localization of CD8+FOXP3+ with CD4+CD8+ cells predicts favorable outcome in follicular lymphoma

The spatial architecture of the lymphoid tissue in follicular lymphoma (FL) presents unique challenges to studying its immune microenvironment. We investigated the spatial interplay of T cells, macrophages, myeloid cells and natural killer T cells using multispectral immunofluorescence images of diagnostic biopsies of 32 patients. A deep learning-based image analysis pipeline was tailored to the needs of follicular lymphoma spatial histology research, enabling the identification of different immune cells within and outside neoplastic follicles. We analyzed the density and spatial co-localization of immune cells in the inter-follicular and intra-follicular regions of follicular lymphoma. Low inter-follicular density of CD8+FOXP3+ cells and co-localization of CD8+FOXP3+ with CD4+CD8+ cells were significantly associated with relapse (p = 0.0057 and p = 0.0019, respectively) and shorter time to progression after first-line treatment (Logrank p = 0.0097 and log-rank p = 0.0093, respectively). A low inter-follicular density of CD8+FOXP3+ cells is associated with increased risk of relapse independent of follicular lymphoma international prognostic index (FLIPI) (p = 0.038, Hazard ratio (HR) = 0.42 [0.19, 0.95], but not independent of co-localization of CD8+FOXP3+ with CD4+CD8+ cells (p = 0.43). Co-localization of CD8+FOXP3+ with CD4+CD8+ cells is predictors of time to relapse independent of the FLIPI score and density of CD8+FOXP3+ cells (p = 0.027, HR = 0.0019 [7.19 × 10-6 , 0.49], This suggests a potential role of inter-follicular CD8+FOXP3+ and CD4+CD8+ cells in the disease progression of FL, warranting further validation on larger patient cohorts.

Lymphoma Microenvironment in DLBCL and PTCL-NOS: the key to uncovering heterogeneity and the potential for stratification

Diffuse large B-cell lymphoma (DLBCL) and peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) are the most common subtypes of mature B cell neoplasm and T/NK cell lymphoma, respectively. They share a commonality in that they are, by definition, highly heterogeneous populations. Recent studies are revealing more about the heterogeneity of these diseases, and at the same time, there is an active debate on how to stratify these heterogeneous diseases and make them useful in clinical practice. The various immune cells and non-cellular components surrounding lymphoma cells, i.e., the lymphoma microenvironment, have been the subject of intense research since the late 2000s, and much knowledge has been accumulated over the past decade. As a result, it has become clear that the lymphoma microenvironment, despite its paucity in tissues, significantly impacts the lymphoma pathogenesis and clinical behavior, such as its prognosis and response to therapy. In this article, we review the role of the lymphoma microenvironment in DLBCL and PTCL-NOS, with particular attention given to its impact on the prognosis and stratification.

Genetics of Transformed Follicular Lymphoma

Histological transformation (HT) to a more aggressive disease–mostly diffuse large B-cell lymphoma–is considered one of the most dismal events in the clinical course of follicular lymphoma (FL). Current knowledge has not found a single biological event specific for HT, although different studies have highlighted common genetic alterations, such as TP53 and CDKN2A/B loss, and MYC translocations, among others. Together, they increase genomic complexity and mutational burden at HT. A better knowledge of HT pathogenesis would presumably help to find diagnostic biomarkers allowing the identification of patients at high-risk of transformation, as well as the discrimination from patients with FL recurrence, and those who remain in remission. This would also help to identify new drug targets and the design of clinical trials for the treatment of transformation. In the present review we provide a comprehensive overview of the genetic events frequently identified in transformed FL contributing to the switch towards aggressive behaviour, and we will discuss current open questions in the field of HT.

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.

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.

Prognostic implication of CTLA-4, PD-1, and PD-L1 expression in aggressive adult T-cell leukemia-lymphoma

The prognosis of patients with aggressive adult T cell leukemia-lymphoma (ATLL) is dismal even with intensive chemotherapy. Allogeneic hematopoietic stem cell transplantation (HSCT) is a promising option for patients with aggressive ATLL, but the posttransplant outcome remains unsatisfactory. Hence, to further improve clinical outcomes, novel therapeutic approaches are needed. The clinical significance of immune checkpoint protein expression has not been well-established in aggressive ATLL. This study aims to identify the association between the expression profile of immune checkpoint proteins on ATLL cells and clinical outcomes. This retrospective study cohort included 65 patients with aggressive ATLL diagnosed between 2001 and 2015 at the National Cancer Center Hospital, Tokyo, Japan. Formalin-fixed paraffin-embedded tissue was used to immunohistochemically determine the expression of immune checkpoint proteins and assess the impact of expression profile on the probability of overall survival from diagnosis or HSCT. The current analysis shows that cytotoxic T lymphocyte antigen-4 (CTLA-4), programmed death-1 (PD-1), and programmed death-ligand 1 (PD-L1) expressions were adverse prognostic factors in patients with aggressive ATLL. Experiments that assess the efficacy of immune checkpoint inhibitors are warranted to alleviate the adverse impacts associated with negative immune checkpoints.

The role of B cells in the development, progression, and treatment of lymphomas and solid tumors

B cells are integral components of the mammalian immune response as they have the ability to generate antibodies against an almost infinite array of antigens. Over the past several decades, significant scientific progress has been made in understanding that this enormous B cell diversity contributes to pathogen clearance. However, our understanding of the humoral response to solid tumors and to tumor-specific antigens is unclear. In this review, we first discuss how B cells interact with other cells in the tumor microenvironment and influence the development and progression of various solid tumors. The ability of B lymphocytes to generate antibodies against a diverse repertoire of antigens and subsequently tailor the humoral immune response to specific pathogens relies on their ability to undergo genomic alterations during their development and differentiation. We will discuss key transforming events that lead to the development of B cell lymphomas. Overall, this review provides a foundation for innovative therapeutic interventions for both lymphoma and solid tumor malignancies.

Low CCL19 expression is associated with adverse clinical outcomes for follicular lymphoma patients treated with chemoimmunotherapy

Background

This study aimed to recognize the hub genes associated with prognosis in follicular lymphoma (FL) treated with first-line rituximab combined with chemotherapy.

Method

RNA sequencing data of dataset GSE65135 (n = 24) were included in differentially expressed genes (DEGs) analysis. Weighted gene co-expression network analysis (WGCNA) was applied for exploring the coexpression network and identifying hub genes. Validation of hub genes expression and prognosis were applied in dataset GSE119214 (n = 137) and independent patient cohort from Cancer Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College (n = 32), respectively, by analyzing RNAseq expression data and serum protein concentration quantified by ELISA. The Gene Set Enrichment Analysis (GSEA), gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichments analysis were performed. CIBERSORT was applied for tumor-infiltrating immune cells (TIICs) subset analysis.

Results

A total of 3260 DEGs were obtained, with 1861 genes upregulated and 1399 genes downregulated. Using WGCNA, eight hub genes, PLA2G2D, MMP9, PTGDS, CCL19, NFIB, YAP1, RGL1, and TIMP3 were identified. Kaplan–Meier analysis and multivariate COX regression analysis indicated that CCL19 independently associated with overall survival (OS) for FL patients treated with rituximab and chemotherapy (HR = 0.47, 95% CI [0.25–0.86], p = 0.014). Higher serum CCL19 concentration was associated with longer progression-free survival (PFS, p = 0.014) and OS (p = 0.039). TIICs subset analysis showed that CCL19 expression had a positive correlation with monocytes and macrophages M1, and a negative correlation with naïve B cells and plasma cells.

Conclusion

CCL19 expression was associated with survival outcomes and might be a potential prognostic biomarker for FL treated with first-line chemoimmunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03078-9.

New Insights into the Biology and Diagnosis of Splenic Marginal Zone Lymphomas

Splenic marginal zone lymphoma (SMZL) is a small B-cell lymphoma, which has been recognized as a distinct pathological entity since the WHO 2008 classification. It classically presents an indolent evolution, but a third of patients progress rapidly and require aggressive treatments, such as immuno-chemotherapy or splenectomy, with all associated side effects. In recent years, advances in the comprehension of SMZL physiopathology have multiplied, thanks to the arrival of new devices in the panel of available molecular biology techniques, allowing the discovery of new molecular findings. In the era of targeted therapies, an update of current knowledge is needed to guide future researches, such as those on epigenetic modifications or the microenvironment of these lymphomas.

An Immune-Clinical Prognostic Index (ICPI) for Patients With De Novo Follicular Lymphoma Treated With R-CHOP/CHOP Chemotherapy

Purpose

Although the role of tumor-infiltrating T cells in follicular lymphoma (FL) has been reported previously, the prognostic value of peripheral blood T lymphocyte subsets has not been systematically assessed. Thus, we aim to incorporate T-cell subsets with clinical features to develop a predictive model of clinical outcome.

Methods

We retrospectively screened a total of 1,008 patients, including 252 newly diagnosed de novo FL patients with available peripheral blood T lymphocyte subsets who were randomized to different sets (177 in the training set and 75 in the internal validation set). A nomogram and a novel immune-clinical prognostic index (ICPI) were established according to multivariate Cox regression analysis for progression-free survival (PFS). The concordance index (C-index), Akaike’s information criterion (AIC), and likelihood ratio chi-square were employed to compare the ICPI’s discriminatory capability and homogeneity to that of FLIPI, FLIPI2, and PRIMA-PI. Additional external validation was performed using a dataset (n = 157) from other four centers.

Results

In the training set, multivariate analysis identified five independent prognostic factors (Stage III/IV disease, elevated lactate dehydrogenase (LDH), Hb <120g/L, CD4+ <30.7% and CD8+ >36.6%) for PFS. A novel ICPI was established according to the number of risk factors and stratify patients into 3 risk groups: high, intermediate, and low-risk with 4-5, 2-3, 0-1 risk factors respectively. The hazard ratios for patients in the high and intermediate-risk groups than those in the low-risk were 27.640 and 2.758. The ICPI could stratify patients into different risk groups both in the training set (P < 0.0001), internal validation set (P = 0.0039) and external validation set (P = 0.04). Moreover, in patients treated with RCHOP-like therapy, the ICPI was also predictive (P < 0.0001). In comparison to FLIPI, FLIPI2, and PRIMA-PI (C-index, 0.613-0.647), the ICPI offered adequate discrimination capability with C-index values of 0.679. Additionally, it exhibits good performance based on the lowest AIC and highest likelihood ratio chi-square score.

Conclusions

The ICPI is a novel predictive model with improved prognostic performance for patients with de novo FL treated with R-CHOP/CHOP chemotherapy. It is capable to be used in routine practice and guides individualized precision therapy.

Hepatitis B surface antigen positivity is associated with progression of disease within 24 months in follicular lymphoma

PURPOSE

Studies have reported a positive association between hepatitis B surface antigen (HBsAg)-positive hepatitis B virus (HBV) infection and follicular lymphoma (FL). Nevertheless, clinical information concerning chronic HBV infection in FL is sparse.

METHODS

This retrospective cohort study investigated the prognostic impact of HBsAg in immunocompetent patients with FL treated with frontline rituximab-containing chemoimmunotherapy in an HBV-endemic area between 2006 and 2016.

RESULTS

Among the 149 analyzed patients, 32 (21.5%) were HBsAg-positive. HBsAg positivity was positively associated with symptomatic splenomegaly, significant serous effusions, and peritreatment hepatic dysfunction. HBsAg-positive patients had a trend of lower complete remission rate (59.4% vs. 76.9%, P = 0.07), significantly poorer overall survival (hazard ratio for death, 2.68; 95% confidence interval, 1.21-5.92), and shorter progression-free survival than had HBsAg-negative patients. Multivariate analysis revealed that HBsAg is an independent adverse prognostic factor for overall survival. Intriguingly, HBsAg-positive patients had a higher incidence of progression of disease within 24 months (POD24) than had HBsAg-negative patients (cumulative incidence rate, 25.8% vs. 12.4%, P = 0.045).

CONCLUSION

This study revealed that patients with FL and chronic HBV infection represent a distinct subgroup with a markedly poor prognosis. HBsAg was positively associated with POD24 and might serve as a new prognostic predictor of the survival of FL patients in endemic regions for HBV infection.

Expression of KLRG1 and CD127 defines distinct CD8+ subsets that differentially impact patient outcome in follicular lymphoma

Background

CD8⁺ T-lymphocyte subsets defined by killer lectin-like receptor G1 (KLRG1) and CD127 expression have been reported to have an important role in infection, but their role in the setting of lymphoid malignancies, specifically follicular lymphoma (FL), has not been studied.

Methods

To characterize the phenotype of KLRG1/CD127-defined CD8⁺ subsets, surface and intracellular markers were measured by flow cytometry and Cytometry by time of flight (CyTOF), and the transcriptional profile of these cells was determined by CITE-Seq (Cellular Indexing of Transcriptomes and Epitopes by Sequencing). The functional capacity of each subset was determined, as was their impact on overall survival (OS) and event-free survival (EFS) of patients with FL.

Results

We found that intratumoral CD8⁺ cells in FL are skewed toward effector cell subsets, particularly KLRG⁺CD127^- and KLRG1^-CD127^- cells over memory cell subsets, such as KLRG1^-CD127⁺ and KLRG1⁺CD127⁺ cells. While effector subsets exhibited increased capacity to produce cytokines/granules when compared with memory subsets, their proliferative capacity and viability were found to be substantially inferior. Clinically, a skewed distribution of intratumoral CD8⁺ T cells favoring effector subtypes was associated with an inferior outcome in patients with FL. Increased numbers of CD127⁺KLRG1^- and CD127⁺KLRG1⁺ were significantly associated with a favorable OS and EFS, while CD127^-KLRG1^- correlated with a poor EFS and OS in patients with FL. Furthermore, we demonstrated that interleukin (IL)-15 promotes CD127^-KLRG1⁺ cell development in the presence of dendritic cells via a phosphoinositide 3-kinase (PI3K)-dependent mechanism, and treatment of CD8⁺ T cells with a PI3K inhibitor downregulated the transcription factors responsible for CD127^-KLRG1⁺ differentiation.

Conclusions

Taken together, these results reveal not only a biological and prognostic role for KLRG1/CD127-defined CD8⁺ subsets in FL but also a potential role for PI3K inhibitors to manipulate the differentiation of CD8⁺ T cells, thereby promoting a more effective antitumor immune response.

PD-1 and LAG-3 Checkpoint Blockade: Potential Avenues for Therapy in B-Cell Lymphoma

The dependence of cancer on an immunotolerant tumor microenvironment (TME) is well established. Immunotherapies that overcome tumor-induced immune suppression have been central to recent advancements in oncology. This is highlighted by the success of agents that interrupt PD-1 mediated immune suppression in a range of cancers. However, while PD-1 blockade has been paradigm-shifting in many malignancies, the majority of cancers show high rates of primary resistance to this approach. This has led to a rapid expansion in therapeutic targeting of other immune checkpoint molecules to provide combination immune checkpoint blockade (ICB), with one such promising approach is blockade of Lymphocyte Activation Gene 3 (LAG-3). Clinically, lymphoproliferative disorders show a wide spectrum of responses to ICB. Specific subtypes including classical Hodgkin lymphoma have demonstrated striking efficacy with anti-PD-1 therapy. Conversely, early trials of ICB have been relatively disappointing in common subtypes of Non-Hodgkin lymphoma. In this review, we describe the TME of common lymphoma subtypes with an emphasis on the role of prominent immune checkpoint molecules PD-1 and LAG3. We will also discuss current clinical evidence for ICB in lymphoma and highlight key areas for further investigation where synergistic dual checkpoint blockade of LAG-3 and PD-1 could be used to overcome ICB resistance.

Clinicopathological factors and tumor microenvironment markers predicting watch-and-wait discontinuation in 82 patients with follicular lymphoma

OBJECTIVES

In this study, we aimed to determine the clinicopathological factors influencing the treatment-free period in patients with follicular lymphoma (FL) using a watch-and-wait (WW) strategy.

METHODS

We retrospectively assessed histopathological parameters of 82 patients with FL.

RESULTS

The median time from diagnosis to WW discontinuation was 62 months (range, 3-138), and median follow-up was 86 months (range, 3-183). Intermediate or high-risk Follicular Lymphoma International Prognostic Index score (P = .012), non-duodenal-type (P = .011), higher numbers of interfollicular CD4⁺ (P = .038) and intrafollicular FOXP3⁺ cells (P = .024) in the tumor microenvironment, and Ki-67 index ≥10% (P = .031) were significant adverse factors for WW discontinuation in univariate analyses.

CONCLUSION

Patients with adverse factors for WW discontinuation should be carefully observed during follow-up.

PD-1 Expression in Pre-Treatment Follicular Lymphoma Predicts the Risk of Subsequent High-Grade Transformation

Purpose

Follicular lymphoma (FL) is an indolent, yet generally incurable neoplasia with a median survival exceeding 10 years. However, a subset of FL patients experiences histological transformation (HT) to a more aggressive lymphoma, in the majority of cases to diffuse large B-cell lymphoma (DLBCL). This affects both the clinical course and the prognostic outcome, resulting in a markedly reduced survival after transformation. Thus, early risk stratification and prediction of patients at risk of HT would be highly valuable in the clinical setting. Here, we investigated the potential of the immune inhibitory programmed death 1 (PD-1) receptor as a biomarker predictive of HT.

Patients and Methods

Immunohistochemical staining and quantification by digital image analysis of PD-1 was performed on diagnostic tumor-tissue samples from FL patients with and without subsequent transformation (n=34 and n=46, respectively), and on paired samples from the transformed lymphoma (n=34).

Results

At the time of initial FL diagnosis, samples from patients with subsequent HT had significantly higher tumor-tissue expression of PD-1 compared with diagnostic FL samples from patients without subsequent HT (p=0.010). At the time of transformation, PD-1 expression was significantly reduced (p<0.001). No difference was observed in intra-follicular PD-1 expression at FL diagnosis between samples from patients with or without HT; however, high intra-follicular levels of PD-1 were associated with significantly shorter transformation-free survival times (p<0.043).

Conclusion

Our data suggest that pre-treatment tumor-tissue PD-1 expression already predicts the risk of subsequent transformation to DLBCL, as early as the time of FL diagnosis.

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.

Overcoming the Hurdles of Autologous T-Cell-Based Therapies in B-Cell Non-Hodgkin Lymphoma

Simple Summary

The activity of novel therapies that utilize patient’s own T-cells to induce remission of B-cell non-Hodgkin lymphoma (B-NHL), including chronic lymphocytic leukemia (CLL), is still suboptimal. In this review, we summarize the clinical efficacy of T-cell-based therapies in B-NHL and provide a biologic rationale for the observed (lack of) responses. We describe and compare the acquired T-cell dysfunctions that occur in the different subtypes of B-NHL. Furthermore, we discuss new insights that could enhance the efficacy of T-cell-based therapies for B-NHL and CLL.

Abstract

The next frontier towards a cure for B-cell non-Hodgkin lymphomas (B-NHL) is autologous cellular immunotherapy such as immune checkpoint blockade (ICB), bispecific antibodies (BsAbs) and chimeric antigen receptor (CAR) T-cells. While highly successful in various solid malignancies and in aggressive B-cell leukemia, this clinical success is often not matched in B-NHL. T-cell subset skewing, exhaustion, expansion of regulatory T-cell subsets, or other yet to be defined mechanisms may underlie the lack of efficacy of these treatment modalities. In this review, a systematic overview of results from clinical trials is given and is accompanied by reported data on T-cell dysfunction. From these results, we distill the underlying pathways that might be responsible for the observed differences in clinical responses towards autologous T-cell-based cellular immunotherapy modalities between diffuse large B-cell lymphoma (DLBCL), chronic lymphocytic leukemia (CLL), follicular lymphoma (FL), mantle cell lymphoma (MCL), and marginal zone lymphoma (MZL). By integration of the clinical and biological findings, we postulate strategies that might enhance the efficacy of autologous-based cellular immunotherapy for the treatment of B-NHL.

The effect of PD-1 expression on tumor-associated macrophage in T cell lymphoma

PURPOSE

Our study aimed to explore the programmed death 1 (PD-1) expression on tumor-associated macrophage (TAM) in T cell non-Hodgkin lymphoma (T-NHL) and its relationship with lymphoma prognosis. The effect of PD-1 expression on the function of macrophages was also studied.

METHODS

Multispectral image quantitative analysis was applied for detecting PD-1 expression on macrophages in T cell lymphoma tissues. The Kaplan-Meier analysis was performed to evaluate the value of PD-1 expression of TAM in predicting the overall survival of T-NHL. PD-1 overexpression THP-1-derived macrophage was constructed and was cocultured with Jurkat cells to explore the effect of PD-1 on macrophage function.

RESULTS

In 17 T cell lymphoma cases, the 1-year overall survival rate was significantly lower in patients with higher PD-1 expression on TAMs (0.25 vs 0.86, p < 0.05). After co-cultured with Jurkat cells, classically activated (M1)-related markers on PD-1 overexpressed macrophages were significantly lower than those on controls, while the expressions of alternatively activated (M2) related markers were similar. The PD-1 overexpressed macrophages showed inhibited phagocytosis (4.42% vs 40.7%, p < 0.001) and increased IL-10 secretion (144.48 pg/ml vs 32.32 pg/ml, p < 0.001).

CONCLUSION

High PD-1 expression on TAMs in T-NHL may predict poor prognosis. The PD-1 overexpression of macrophages significantly inhibited polarization of M1 macrophages and phagocytosis, and more IL-10 was excreted. These changes may enhance the pro-tumor effects of tumor microenvironment.

MiR-7e-5p downregulation promotes transformation of low-grade follicular lymphoma to aggressive lymphoma by modulating an immunosuppressive stroma through the upregulation of FasL in M1 macrophages

BACKGROUND

In follicular lymphoma (FL), histologic transformation to high-grade FL and diffuse large B-cell lymphoma (DLBCL) is a critical adverse step in disease progression. Activation of the oncogene c-MYC and tumor microenvironment remodeling account for FL progression. A panel of microRNA (miRNA) was downregulated in transformed FL (tFL).

METHODS

Differentially expressed miRNAs were systematically compared in 11 lymph nodes from patients at different stages of disease. Expression of miR-7e-5p was analyzed in 46 B-cell lymphomas, including 30 FL tissues and 16 DLBCL tissues. In FL cells, transcriptional regulation of the oncogene c-MYC on its target miR-7e-5p was revealed by Chromatin Immunoprecipitation (ChIP) assay. Exosome, carrying differentially expressed miR-7e-5p was isolated and visualized by transmission electron microscope and fluorescence tracing. The effect of miR-7e-5p on recipient macrophage was determined by target gene quantification, flow cytometry, and TUNEL method in a cocultured system with miR-7e-5p-mimics or inhibitors treatment. Expression of miR-7e-5p targets, macrophage proportions, and clinical parameters were included for correlation analysis.

RESULTS

We determined that downregulation of miR-7e-5p, driven by c-MYC overexpression, was associated with poorer prognosis in FL patients. The decreased expression of miR-7e-5p in lymphoma cells led to a reduced exosomal transfer to surrounding macrophages. As a result, the target gene of miR-7e-5p, Fas ligand (FasL), was upregulated and activated the caspase signaling, which led to the apoptosis of M1 macrophages in tumor stroma. Finally, in transformed FL tissues, overexpression of FasL and activation of caspase proteins was detected in tumor stromal macrophages. Downregulation of miR-7e-5p was associated with poorer clinical outcomes.

CONCLUSION

Downregulation of exosomal miR-7e-5p induces stromal M1 macrophage apoptosis, which leads to immunosurveillance and transformation of FL.

Current Clinical Applications and Future Perspectives of Immune Checkpoint Inhibitors in Non-Hodgkin Lymphoma

Cancer cells escape immune recognition by exploiting the programmed cell-death protein 1 (PD-1)/programmed cell-death 1 ligand 1 (PD-L1) immune checkpoint axis. Immune checkpoint inhibitors that target PD-1/PD-L1 unleash the properties of effector T cells that are licensed to kill cancer cells. Immune checkpoint blockade has dramatically changed the treatment landscape of many cancers. Following the cancer paradigm, preliminary results of clinical trials in lymphoma have demonstrated that immune checkpoint inhibitors induce remarkable responses in specific subtypes, most notably classical Hodgkin lymphoma and primary mediastinal B-cell lymphoma, while in other subtypes, the results vary considerably, from promising to disappointing. Lymphomas that respond to immune checkpoint inhibitors tend to exhibit tumor cells that reside in a T-cell-rich immune microenvironment and display constitutive transcriptional upregulation of genes that facilitate innate immune resistance, such as structural variations of the PD-L1 locus, collectively referred to as T-cell-inflamed lymphomas, while those lacking such characteristics are referred to as noninflamed lymphomas. This distinction is not necessarily a sine qua non of response to immune checkpoint inhibitors, but rather a framework to move the field forward with a more rational approach. In this article, we provide insights on our current understanding of the biological mechanisms of immune checkpoint evasion in specific subtypes of B-cell and T-cell non-Hodgkin lymphomas and summarize the clinical experience of using inhibitors that target immune checkpoints in these subtypes. We also discuss the phenomenon of hyperprogression in T-cell lymphomas, related to the use of such inhibitors when T cells themselves are the target cells, and consider future approaches to refine clinical trials with immune checkpoint inhibitors in non-Hodgkin lymphomas.

An integrative microenvironment approach for follicular lymphoma: roles of inflammatory cell subsets and immune-response polymorphisms on disease clinical course

The study of the tumor microenvironment (TME) in follicular lymphoma (FL) has produced conflicting results due to assessment of limited TME subpopulations, and because of heterogeneous treatments among different cohorts. Also, important genetic determinants of immune response, such as single-nucleotide polymorphisms (SNPs), remain underexplored in this disease. We performed a detailed study of the TME in 169 FL biopsies using immunohistochemistry, encompassing lymphocytes, macrophages, and cytokines. We also genotyped 16 SNPs within key immune-response genes (IL12A, IL2, IL10, TGFB1, TGFBR1, TGFBR2, IL17A, and IL17F) in 159 patients. We tested associations between SNPs, clinicopathological features and TME composition, and proposed survival models in R-CHOP/R-CVP-treated patients. Presence of the IL12A rs568408 "A" allele associated with the follicular pattern of FOXP3+ cells. The IL12A AA haplotype included rs583911 and rs568408 and was an independent predictor of worse survival, together with the follicular patterns of T-cells (FOXP3+ and CD8+) and high IL-17F tumor levels. The patterns of CD3+, CD4+ and CD8+ cells, displayed as a principal component, also associated with survival. Hierarchical clustering of the TME proteins demonstrated a cluster that was associated with worse prognosis (tumors enriched in IL-17A, IL-17F, CD8, PD1, and Ki-67). The survival of FL patients who were treated in the rituximab era shows a strong dependence on TME signals, especially the T-cell infiltration patterns and IL-17F tumor levels. The presence of the AA haplotype of IL12A in the genome of FL patients is an additional prognostic factor that may modulate the composition of T-reg cells in this disease.

The Biological Basis of Histologic Transformation

Histologic transformation of follicular lymphoma remains the leading cause of follicular lymphoma-related mortality in the rituximab era. Both the diverse timing of transformation and heterogeneity in associated genomic events suggest that histologic transformation may itself comprise distinct disease entities. Successive indolent and transformation episodes occur by divergent clonal evolution from an inferred common progenitor cell, representing a potential therapeutic target. Existing biological knowledge largely pre-dates anti-CD20 therapy, and further prospective validation is essential. Inclusion of transformation cases in clinical trials incorporating biomarker discovery, and an integrated understanding of the genetic and microenvironmental factors underpinning transformation, may unearth renewed clinical opportunities.

PD1 distribution pattern, regardless of the cell origin, is an independent microenvironmental prognostic factor for progression-free survival in follicular lymphoma

Follicular lymphoma (FL) is a well-studied microenvironment-dependent hematological malignancy, but the crosstalk between various involved cell subtypes is still not fully understood. Recent promising results of immunotherapy in recurrent FL warrant the need for an in-depth analysis of the expression and role of immune system-related proteins in the FL microenvironment. Seventy-one patients with FL and available diagnostic paraffin blocks were enrolled in the retrospective analysis. Histopathological diagnoses were revised according to the World Health Organization recommendations. Patients were either observed (watch and wait/W&W group) or immediately treated with chemo(immuno)therapy regimens according to their clinical status. Immunohistochemical assessment of PD1, PDL1, CD4, CD8, CD163, CD68-KP1, CD68-PGM1 was performed. The scoring methods included both semi-quantitative estimation of positive cells and architectural pattern distribution. The differences between PD1 staining distribution and intensity were classified as intra/perifollicular vs. interfollicular/diffuse cells and presented bright vs. dim immunoreactivity, respectively. No statistically significant differences in the density distribution of the immunohistochemical stainings were found between W&W and chemo(immuno)therapy groups. Interfollicular/diffuse pattern of PD1 expression had significantly decreased progression-free survival when analyzing the whole cohort and patients on chemo(immuno)therapy (p = 0.014 and p = 0.07, respectively). The high dependence was not significant in the W&W group. PD1 positivity of cells did not correlate with CD4 or CD8 immunophenotype. Morphologically FL neoplastic cells were entirely PDL1 negative, but granular and membranous staining was detected in the FL microenvironment. In line with previous studies, PD1/PDL1 expression was predominantly localized in the FL microenvironment, indicating that FL cells might not be the direct target for anti-PDL1 therapy. However, we show that the localization of PD1 expression could be a viable progression-free survival biomarker for FL.

The architecture of neoplastic follicles in follicular lymphoma; analysis of the relationship between the tumor and follicular helper T cells

CD4+ T-follicular helper cells are essential for the survival, proliferation, and differentiation of germinal center B cells and have been implicated in the pathogenesis of follicular lymphoma (FL). To further define the role of these cells in FL, we used multiparameter confocal microscopy to compare the architecture of normal and neoplastic follicles and next generation sequencing to analyze the T-cell receptor repertoire in FL lymph nodes (LN). Multiparameter analysis of LN showed that the proportion of T-follic-ular helper cells (TFH) in normal and neoplastic follicles is the same and that the previously reported increase in TFH numbers in FL is thus due to an increase in the number and not content of follicles. As in normal germinal centers, TFH were shown to have a close spatial correlation with proliferating B cells in neoplastic follicles, where features of immunological synapse formation were observed. The number of TFH in FL correlate with the rate of B-cell proliferation and TFH co-localized to activation induced cytidine deaminase expressing proliferating B cells. T-cell receptor repertoire analysis of FL LN revealed that follicular areas are significantly more clonal when compared to the rest of the LN. These novel findings show that neoplastic follicles and germinal centers share important structural features and provide further evidence that TFH may play a role in driving B-cell proliferation and genomic evolution in TFH Our results also suggest that targeting this interaction would be an attractive therapeutic option.

Mass Cytometry Analysis Reveals that Specific Intratumoral CD4+ T Cell Subsets Correlate with Patient Survival in Follicular Lymphoma

Follicular lymphoma (FL) is an indolent B cell malignancy characterized by an extensive but poorly functional T cell infiltrate in the tumor microenvironment. Using mass cytometry, we identified at least 12 subsets of intratumoral CD4⁺ T cells, 3 of which were unique to FL biopsies versus control tissues. Of these subsets, the frequency of naive T cells correlated with improved patient survival. Although total PD-1⁺ T cell numbers were not associated with patient outcome, specific PD-1⁺ T cell subpopulations were associated with poor survival. Intratumoral T cells lacking CD27 and CD28 co-stimulatory receptor expression were enriched in FL and correlated with inferior patient outcomes. In vitro models revealed that CD70⁺ lymphoma cells played an important role in expanding this population. Taken together, our mass cytometry results identified CD4⁺ memory T cell populations that are poorly functional due to loss of co-stimulatory receptor expression and are associated with an inferior survival in FL.

Yang et al. utilize mass cytometry (CyTOF) to characterize intratumoral T cells and explore the clinical relevance of T cell subsets in follicular lymphoma (FL). Clustering analysis reveals an immune signature with reduced expression of co-stimulatory molecules on intratumoral T cells that correlated with a poor prognosis in FL.

Advances in targeted therapy for malignant lymphoma

The incidence of lymphoma has gradually increased over previous decades, and it ranks among the ten most prevalent cancers worldwide. With the development of targeted therapeutic strategies, though a subset of lymphoma patients has become curable, the treatment of refractory and relapsed diseases remains challenging. Many efforts have been made to explore new targets and to develop corresponding therapies. In addition to novel antibodies targeting surface antigens and small molecular inhibitors targeting oncogenic signaling pathways and tumor suppressors, immune checkpoint inhibitors and chimeric antigen receptor T-cells have been rapidly developed to target the tumor microenvironment. Although these targeted agents have shown great success in treating lymphoma patients, adverse events should be noted. The selection of the most suitable candidates, optimal dosage, and effective combinations warrant further investigation. In this review, we systematically outlined the advances in targeted therapy for malignant lymphoma, providing a clinical rationale for mechanism-based lymphoma treatment in the era of precision medicine.

Recovery of central memory and naive peripheral T cells in Follicular Lymphoma patients receiving rituximab-chemotherapy based regimen

Preclinical models and clinical studies have shown that anti-CD20-based treatment has multifaceted consequences on T-cell immunity. We have performed a prospective study of peripheral T-cell compartment in FL patients, all exhibiting high tumor burden and receiving rituximab-chemotherapy-based regimen (R-CHOP). Before treatment, FL patients harbor low amounts of peripheral naive T cells, but high levels of CD4⁺ T_EM, CD4⁺ T_reg and CD8⁺ T_EMRA subsets and significant amounts of CD38⁺ HLA-DR⁺ activated T cells. A portion of these activated/differentiated T cells also expressed PD-1 and/or TIGIT immune checkpoints. Hierarchical clustering of phenotyping data revealed that 5/8 patients with only a partial response to R-CHOP induction therapy or with disease progression segregate into a group exhibiting a highly activated/differentiated T cell profile and a markedly low proportion of naive T cells before treatment. Rituximab-based therapy induced a shift of CD4⁺ and CD8⁺ T cells toward a central memory phenotype and of CD8⁺ T cells to a naive phenotype. In parallel, a decrease in the number of peripheral T cells expressing both PD-1 and TIGIT was detected. These observations suggest that the standard rituximab-based therapy partially reverts the profound alterations observed in T-cell subsets in FL patients, and that blood T-cell phenotyping could provide a better understanding of the mechanisms of rituximab-based treatment.

Progression of Disease Within 24 Months in Follicular Lymphoma Is Associated With Reduced Intratumoral Immune Infiltration

PURPOSE

Understanding the immunobiology of the 15% to 30% of patients with follicular lymphoma (FL) who experience progression of disease within 24 months (POD24) remains a priority. Solid tumors with low levels of intratumoral immune infiltration have inferior outcomes. It is unknown whether a similar relationship exists between POD24 in FL.

PATIENTS AND METHODS

Digital gene expression using a custom code set—five immune effector, six immune checkpoint, one macrophage molecules—was applied to a discovery cohort of patients with early- and advanced-stage FL (n = 132). T-cell receptor repertoire analysis, flow cytometry, multispectral immunofluorescence, and next-generation sequencing were performed. The immune infiltration profile was validated in two independent cohorts of patients with advanced-stage FL requiring systemic treatment (n = 138, rituximab plus cyclophosphamide, vincristine, prednisone; n = 45, rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone), with the latter selected to permit comparison of patients experiencing a POD24 event with those having no progression at 5 years or more.

RESULTS

Immune molecules showed distinct clustering, characterized by either high or low expression regardless of categorization as an immune effector, immune checkpoint, or macrophage molecule. Low programmed death-ligand 2 (PD-L2) was the most sensitive/specific marker to segregate patients with adverse outcomes; therefore, PD-L2 expression was chosen to distinguish immune infiltration^HI (ie, high PD-L2) FL biopsies from immune infiltration^LO (ie, low PD-L2) tumors. Immune infiltration^HI tissues were highly infiltrated with macrophages and expanded populations of T-cell clones. Of note, the immune infiltration^LO subset of patients with FL was enriched for POD24 events (odds ratio [OR], 4.32; c-statistic, 0.81; P = .001), validated in the independent cohorts (rituximab plus cyclophosphamide, vincristine, prednisone: OR, 2.95; c-statistic, 0.75; P = .011; and rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone: OR, 7.09; c-statistic, 0.88; P = .011). Mutations were equally proportioned across tissues, which indicated that degree of immune infiltration is capturing aspects of FL biology distinct from its mutational profile.

CONCLUSION

Assessment of immune-infiltration by PD-L2 expression is a promising tool with which to help identify patients who are at risk for POD24.

Low number of intrafollicular T cells may predict favourable response to rituximab-based immuno-chemotherapy in advanced follicular lymphoma: a secondary analysis of a randomized clinical trial

Background

First-line rituximab therapy together with chemotherapy is the standard care for patients with advanced follicular B-cell lymphoma, as rituximab together with chemotherapy prolongs progression-free and overall survival (Herold et al. 2007; Marcus et al. 2005). However, as not all patient subgroups benefit from combined immuno-chemotherapy, we asked whether the microenvironment may predict benefit from rituximab-based therapy.

Design

To address this question, we performed a retrospective immunohistochemical analysis on pathological specimens of 18 patients recruited into a randomized clinical trial, where patients with advanced follicular lymphoma were randomized into either chemotherapy or immuno-chemotherapy with rituximab (Herold et al. 2007).

Results

We show here that rituximab exerts beneficial effects, especially in the subgroup of follicular lymphoma patients with low intrafollicular CD3, CD5, CD8, and ZAP70 and high CD56 and CD68 expression.

Conclusion

Rituximab may overcome immune-dormancy in follicular lymphoma in cases with lower intrafollicular T-cell numbers and higher CD56 and CD68 cell counts. As this was a retrospective analysis on a small subgroup of patients, these data need to be corroborated in larger clinical trials.

Electronic supplementary material

The online version of this article (10.1007/s00432-019-02961-9) contains supplementary material, which is available to authorized users.

Divergent immunohistochemical expression of CD21 and CD23 by follicular dendritic cells with increasing grade of follicular lymphoma

BACKGROUND

Ultrastructural and immunohistochemical differences have been described in FDCs of primary and secondary follicles, illustrating the highly compartmentalized structure of lymph follicles. Differences in FDC immunophenotype in different grades of FL may reflect some parallelism between reactive and neoplastic conditions in terms of FDC-B cell interaction and may be used as a valuable additional tool for grading FL.

METHODS

A total of 60 paraffin blocks from patients with follicular lymphoma, 30 cases each of grade 1 and 3, were retrieved from our archive. Immunohistochemical analysis was carried out for CD21, CD23, cyclin A, and Ki-67.

RESULTS

Our study demonstrates that during evaluation, six patterns of FDC distribution were distinguished. The intensity of stain for CD21 was not statistically significant in grade 1 and grade 3 FL (p = 0.340). In contrast, grade 3 FLs exhibited a significant decrease of CD23 expression by the FDCs (p < 0.001). By CD21 stain, there was no significant difference in the distribution of pattern 1 in grades 1 and 3 (p = 0.098). In contrast, in grade 3, this pattern was significantly less observed by CD23 stain (p = 0.016). The same was observed for pattern 2 for CD21 (p = 0.940) and CD23 (p = 0.010) and pattern 4 for CD21 (p = 0.305) and CD23 (p = 0.005), respectively. Distribution of pattern 5 was significantly different between grades 1 and 3 both for CD21 (p = 0.005) and CD23 (p < 0.001). Distribution of patterns 2 and 6 was not significantly different between grades 1 and 3 for CD21 and CD23. The values of cyclin A and Mib-1 were also significantly different between grades 1 and 3 (p < 0.001).

CONCLUSIONS

The observed patterns of FDCs lead us to believe that similar to reactive lymph node follicles, neoplastic follicles in FL, at least in early stages, have an organized structure. Hypothetically, with CD21, CD23, and cyclin A immunohistochemistry, the sequence of events in FL progression may be traced.

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.

High TNFRSF14 and low BTLA are associated with poor prognosis in Follicular Lymphoma and in Diffuse Large B-cell Lymphoma transformation

The microenvironment influences the behavior of follicular lymphoma (FL) but the specific roles of the immunomodulatory BTLA and TNFRSF14 (HVEM) are unknown. Therefore, we examined their immunohistochemical expression in the intrafollicular, interfollicular and total histological compartments in 106 FL cases (57M/49F; median age 57-years), and in nine relapsed-FL with transformation to DLBCL (tFL). BTLA expression pattern was of follicular T-helper cells (TFH) in the intrafollicular and of T-cells in the interfollicular compartments. The mantle zones were BTLA+ in 35.6% of the cases with similar distribution of IgD. TNFRSF14 expression pattern was of neoplastic B lymphocytes (centroblasts) and “tingible body macrophages”. At diagnosis, the averages of total BTLA and TNFRSF14-positive cells were 19.2%±12.4STD (range, 0.6%-58.2%) and 46.7 cells/HPF (1-286.5), respectively. No differences were seen between low-grade vs. high-grade FL but tFL was characterized by low BTLA and high TNFRSF14 expression. High BTLA correlated with good overall survival (OS) (total-BTLA, Hazard Risk=0.479, P=0.022) and with high PD-1 and FOXP3+Tregs. High TNFRSF14 correlated with poor OS and progression-free survival (PFS) (total-TNFRSF14, HR=3.9 and 3.2, respectively, P<0.0001), with unfavorable clinical variables and higher risk of transformation (OR=5.3). Multivariate analysis including BTLA, TNFRSF14 and FLIPI showed that TNFRSF14 and FLIPI maintained prognostic value for OS and TNFRSF14 for PFS. In the GSE16131 FL series, high TNFRSF14 gene expression correlated with worse prognosis and GSEA showed that NFkB pathway was associated with the “High-TNFRSF14/dead-phenotype”.

In conclusion, the BTLA-TNFRSF14 immune modulation pathway seems to play a role in the pathobiology and prognosis of FL.

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.

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.

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.

Expression of programmed cell death 1/programmed cell death ligand 1 in the tumor microenvironments of primary gastrointestinal diffuse large B cell lymphomas

BACKGROUND

Gastrointestinal diffuse large B cell lymphoma (GI DLBCL) is the most common gastrointestinal lymphoma. However, there has not been a comprehensive investigation into the expression patterns of programmed cell death 1 (PD-1) and programmed cell death ligand 1(PD-L1) in GI DLBCL tissues.

METHODS

PD-1 protein expression in tumor-infiltrating lymphocytes (TILs) was evaluated by immunohistochemical staining, and expression of PD-L1 was evaluated by using PD-L1/PAX5 immunohistochemical double staining in 92 GI DLBCL specimens.

RESULTS

The prevalence of positive PD-L1 expression (PD-L1 + ) in GI DLBCL cells and positive PD-L1 expression in non-cancer cells of the GI DLBCL microenvironment (microenvironmental PD-L1, mPD-L1) were 11.96% (11 of 92) and 41.98% (34 of 81), respectively. PD-L1 expression in GI DLBCL was significantly associated with involvement of extranodal sites ≥ 2 (P = 0.034) and mPD-L1 expression was significantly associated with ECOG performance status (score ≥ 2) (P = 0.041). PD-L1 expression and mPD-L1 expression had no prognostic significance (P > 0.05) on disease outcome. PD-1+ TILs were significantly lower in patients with extranodal site involvement (P = 0.011) and the quantity of PD-1 + TILs correlated positively with the level of PDL1 expression in non malignant microenvironment cells (P = 0.001). Patients with high levels of PD-1+ TILs had better prognosis (P = 0.0005).

CONCLUSIONS

The expression patterns of PD-L1 in patients with GI DLBCL are different from patients with common DLBCL. Immunotherapies that target the PD-1/PD-L1 pathway may have therapeutic potential in GI DLBCL.

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.

T follicular helper cells: a potential therapeutic target in follicular lymphoma

Follicular lymphoma (FL), the most common indolent B-cell non-Hodgkin lymphoma (B-NHL), is a germinal center (GC)-derived lymphoma. The mechanisms underlying B-cell differentiation/maturation in GCs could be also involved in their malignant transformation. Moreover, the non-malignant cell composition and architecture of the tumor microenvironment can influence FL development and outcome. Here, we review recent research advances on CD4 helper T cells in FL that highlight the pivotal role of T follicular helper (TFH) cells in a complex multicellular system where they interact with B cells during GC dynamics. After describing the mechanism of FL lymphomagenesis, we discuss the emerging evidence about TFH cell enrichment and involvement in FL tumorigenesis and in B-T cell interaction, TFH regulation by T follicular regulatory cells (TFR) and its potential effect on FL. Then, we provide an overview on the flexible interplay between the different CD4 T-cell subtypes and how this may be predicted in normal and pathologic contexts, according to the cell epigenetic state. Finally, we highlight the importance of targeting TFH cells in the clinic, summarize the main outstanding questions about TFH and TFR cells in FL, and describe strategies to potentiate FL therapy by taking into account TFH cells.

Chromatin modifying gene mutations in follicular lymphoma

Follicular lymphoma (FL) is an indolent malignancy of germinal center B cells. Although the overall survival of FL patients has recently improved with the introduction of novel therapies, there is significant heterogeneity in patient outcome and a need for rationally designed therapeutic strategies that target disease biology. Next-generation sequencing studies have identified chromatin modifying gene (CMG) mutations as a hallmark of FL, highlighting epigenetic modifiers as an attractive therapeutic target in this disease. Understanding the complex roles of these mutations will be central to identifying and adaptively targeting associated vulnerabilities. Recent studies have provided insight into the functional consequences of the most frequently mutated CMGs (KMT2D, CREBBP, and EZH2) and point to a role for these events in modifying normal B-cell differentiation programs and impeding germinal center exit. However, the majority of FL tumors serially acquire multiple CMG mutations, suggesting that there is a level of cross talk or cooperation between these events that has not yet been defined. Here, I review the current state of knowledge on CMG mutations in FL, discuss their potential as therapeutic targets, and offer my perspective on unexplored areas that should be considered in the future.

Sites of extranodal involvement are prognostic in patients with stage 1 follicular lymphoma

Objectives

Follicular lymphoma (FL) is the most common indolent B cell lymphoma in the United States and a quarter of patients present with stage I disease. The objective of this study was to examine if primary site of disease influences survival in early stage lymphoma.

Results

The most common extranodal primary sites were the integumentary system (8%), followed by the GI tract (6.4%) and head & neck (5.6%). We stratified patients into a pre-rituximab era (1983-1998) and the rituximab era (1999-2011). In multivariable analysis, integumentary disease was associated with better overall survival (Hazard Ratio [HR], 0.77; Confidence Interval [CI], 0.66-0.9) while primary site FL of the nervous system (HR, 2.40; CI, 1.72-3.38) and the musculoskeletal system (HR, 2.14; CI, 1.44-3.18) were associated with worse overall survival when compared to primary nodal FL. Treatment in the pre-rituximab era, male gender and older age at diagnosis were associated with worse survival.

Methods

We queried the SEER database from 1983 to 2011. We included all adult patients (>18 years) with histologically confirmed stage I FL, active follow-up, and a single primary tumor. A total of 9,865 patients met eligibility criteria, with 2520 (25%) having an extranodal primary site. We classified the primary sites by organ or anatomic location into 11 sites.

Conclusion

Primary site of disease is a prognostic factor for patients with early stage FL and may help identify subsets of patients that could benefit from early, aggressive treatment.

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.