Lack of intrafollicular memory CD4 + T cells is predictive of early clinical failure in newly diagnosed follicular lymphoma

Minimal residual disease detection in lymphoma: methods, procedures and clinical significance

Lymphoma is a highly heterogeneous lymphohematopoietic tumor. As our understanding of the biological and pathological characteristics of lymphoma improves, we are identifying an increasing number of lymphoma subtypes. Genotyping has enhanced our ability to diagnose, treat, and monitor the prognosis of lymphoma. Despite significant improvements in treatment effectiveness, traditional methods for assessing disease response and monitoring prognosis are imperfect, and there is no significant improvement in overall remission rates for lymphoma patients. Minimal Residual Disease (MRD) is often indicative of refractory disease or early relapse. For lymphoma patients, personalized MRD monitoring techniques offer an efficient means to estimate disease remission levels, predict early relapse risk, and assess the effectiveness of new drug regimens. In this review, we delve into the MRD procedures in lymphoma, including sample selection and requirements, detection methods and their limitations and advantages, result interpretation. Besides, we also introduce the clinical applications of MRD detection in lymphoma.

Identification of genetic subtypes in follicular lymphoma

Follicular lymphoma (FL) exhibits considerable variability in biological features and clinical trajectories across patients. To dissect the diversity of FL, we utilized a Bernoulli mixture model to identify genetic subtypes in 713 pre-treatment tumor tissue samples. Our analysis revealed the existence of five subtypes with unique genetic profiles that correlated with clinicopathological characteristics. The clusters were enriched in specific mutations as follows: CS (CREBBP and STAT6), TT (TNFAIP3 and TP53), GM (GNA13 and MEF2B), Q (quiescent, for low mutation burden), and AR (mutations of mTOR pathway-related genes). The subtype Q was enriched for patients with stage I disease and associated with a lower proliferative history than the other subtypes. The AR subtype was unique in its enrichment for IgM-expressing FL cases and was associated with advanced-stage and more than 4 nodal sites. The existence of subtypes was validated in an independent cohort of 418 samples from the GALLIUM trial. Notably, patients assigned to the TT subtype consistently experienced inferior progression-free survival when treated with immunochemotherapy. Our findings offer insight into core pathways distinctly linked with each FL cluster and are expected to be informative in the era of targeted therapies.

Silencing GNAS enhances HDAC3i efficacy in CREBBP wild type B cell lymphoma

The genetic era has opened the opportunity of using personalized therapeutic approaches, in part based on targeting genes with somatic mutations. For example, lymphomas harboring the highly recurrent CREBBP mutation show dependency on HDAC3, thus selective inhibition of HDAC3 reversed the epigenetic effects of CREBBP mutation, halted lymphoma growth, and induced MHC class II expression, enabling the T-cells to recognize and kill lymphoma cells. However, CREBBP wild type (WT) cells are less sensitive to this approach. In this issue of Leukemia, He et al. have executed a genome-wide CRISPR screening that identified GNAS as a target to maximize the therapeutic activity of HDAC3 inhibition in CREBBP WT lymphoma.

Integrated single cell analysis reveals co-evolution of malignant B cells and tumor micro-environment in transformed follicular lymphoma

Histological transformation of follicular lymphoma (FL) to aggressive forms is associated with poor outcome. Phenotypic consequences of this evolution and its impact on the tumor microenvironment (TME) remain unknown. We perform single-cell whole genome sequencing (scWGS) and transcriptome sequencing (scWTS) of 11 paired pre/post-transformation patient samples and scWTS of additional samples from patients without transformation. Our analysis reveals evolutionary dynamics of transformation at single-cell resolution, highlighting a shifting TME landscape, with an emerging immune-cell exhaustion signature, co-evolving with the shifting malignant B phenotype in a regulatory ecosystem. Integration of scWGS and scWTS identifies malignant cell pathways upregulated during clonal tumor evolution. Using multi-color immunofluorescence, we transfer these findings to a TME-based transformation biomarker, subsequently validated in two independent pretreatment cohorts. Taken together, our results provide a comprehensive view of the combined genomic and phenotypic evolution of malignant cells during transformation and shifting crosstalk between malignant cells and the TME.

Cell cross talk within the lymphoma tumor microenvironment: follicular lymphoma as a paradigm

ABSTRACT

Follicular lymphoma (FL) is an indolent yet incurable germinal center B-cell lymphoma retaining a characteristic follicular architecture. FL tumor B cells are highly dependent on direct and indirect interactions with a specific and complex tumor microenvironment (TME). Recently, great progress has been made in describing the heterogeneity and dynamics of the FL TME and in depicting how tumor clonal and functional heterogeneity rely on the integration of TME-related signals. Specifically, the FL TME is enriched for exhausted cytotoxic T cells, immunosuppressive regulatory T cells of various origins, and follicular helper T cells overexpressing B-cell and TME reprogramming factors. FL stromal cells have also emerged as crucial determinants of tumor growth and remodeling, with a key role in the deregulation of chemokines and extracellular matrix composition. Finally, tumor-associated macrophages play a dual function, contributing to FL cell phagocytosis and FL cell survival through long-lasting B-cell receptor activation. The resulting tumor-permissive niches show additional layers of site-to-site and kinetic heterogeneity, which raise questions about the niche of FL-committed precursor cells supporting early lymphomagenesis, clonal evolution, relapse, and transformation. In turn, FL B-cell genetic and nongenetic determinants drive the reprogramming of FL immune and stromal TME. Therefore, offering a functional picture of the dynamic cross talk between FL cells and TME holds the promise of identifying the mechanisms of therapy resistance, stratifying patients, and developing new therapeutic approaches capable of eradicating FL disease in its different ecosystems.

Follicular lymphoma B cells exhibit heterogeneous transcriptional states with associated somatic alterations and tumor microenvironments

Follicular lymphoma (FL) is an indolent non-Hodgkin lymphoma of germinal center origin, which presents with significant biologic and clinical heterogeneity. Using RNA-seq on B cells sorted from 87 FL biopsies, combined with machine-learning approaches, we identify 3 transcriptional states that divide the biological ontology of FL B cells into inflamed, proliferative, and chromatin-modifying states, with relationship to prior GC B cell phenotypes. When integrated with whole-exome sequencing and immune profiling, we find that each state was associated with a combination of mutations in chromatin modifiers, copy-number alterations to TNFAIP3, and T follicular helper cells (Tfh) cell interactions, or primarily by a microenvironment rich in activated T cells. Altogether, these data define FL B cell transcriptional states across a large cohort of patients, contribute to our understanding of FL heterogeneity at the tumor cell level, and provide a foundation for guiding therapeutic intervention.

Tunable PhenoCycler imaging of the murine pre-clinical tumour microenvironments

BACKGROUND

The tumour microenvironment (TME) consists of tumour-supportive immune cells, endothelial cells, and fibroblasts. PhenoCycler, a high-plex single cell spatial biology imaging platform, is used to characterize the complexity of the TME. Researchers worldwide harvest and bank tissues from mouse models which are employed to model a plethora of human disease. With the explosion of interest in spatial biology, these panoplies of archival tissues provide a valuable resource to answer new questions. Here, we describe our protocols for developing tunable PhenoCycler multiplexed imaging panels and describe our open-source data analysis pipeline. Using these protocols, we used PhenoCycler to spatially resolve the TME of 8 routinely employed pre-clinical models of lymphoma, breast cancer, and melanoma preserved as FFPE.

RESULTS

Our data reveal distinct TMEs in the different cancer models that were imaged and show that cell-cell contacts differ depending on the tumour type examined. For instance, we found that the immune infiltration in a murine model of melanoma is altered in cellular organization in melanomas that become resistant to αPD-1 therapy, with depletions in a number of cell-cell interactions.

CONCLUSIONS

This work presents a valuable resource study seamlessly adaptable to any field of research involving murine models. The methodology described allows researchers to address newly formed hypotheses using archival materials, bypassing the new to perform new mouse studies.

Mapping cancer biology in space: applications and perspectives on spatial omics for oncology

Technologies to decipher cellular biology, such as bulk sequencing technologies and single-cell sequencing technologies, have greatly assisted novel findings in tumor biology. Recent findings in tumor biology suggest that tumors construct architectures that influence the underlying cancerous mechanisms. Increasing research has reported novel techniques to map the tissue in a spatial context or targeted sampling-based characterization and has introduced such technologies to solve oncology regarding tumor heterogeneity, tumor microenvironment, and spatially located biomarkers. In this study, we address spatial technologies that can delineate the omics profile in a spatial context, novel findings discovered via spatial technologies in oncology, and suggest perspectives regarding therapeutic approaches and further technological developments.

Location, location, location: mapping the lymphoma tumor microenvironment using spatial transcriptomics

Lymphomas are a heterogenous group of lymphoid neoplasms with a wide variety of clinical presentations. Response to treatment and prognosis differs both between and within lymphoma subtypes. Improved molecular and genetic profiling has increased our understanding of the factors which drive these clinical dynamics. Immune and non-immune cells within the lymphoma tumor microenvironment (TME) can both play a key role in antitumor immune responses and conversely also support lymphoma growth and survival. A deeper understanding of the lymphoma TME would identify key lymphoma and immune cell interactions which could be disrupted for therapeutic benefit. Single cell RNA sequencing studies have provided a more comprehensive description of the TME, however these studies are limited in that they lack spatial context. Spatial transcriptomics provides a comprehensive analysis of gene expression within tissue and is an attractive technique in lymphoma to both disentangle the complex interactions between lymphoma and TME cells and improve understanding of how lymphoma cells evade the host immune response. This article summarizes current spatial transcriptomic technologies and their use in lymphoma research to date. The resulting data has already enriched our knowledge of the mechanisms and clinical impact of an immunosuppressive TME in lymphoma and the accrual of further studies will provide a fundamental step in the march towards personalized medicine.

Thinking "outside the germinal center": Re-educating T cells to combat follicular lymphoma

There have been significant advancements in the management of follicular lymphoma (FL), the most common indolent lymphoma. These include immunomodulatory agents such as lenalidomide, epigenetic modifiers (tazemetostat), and phosphoinotiside-3 kinase inhibitors (copanlisib). The focus of this review is T cell-engager therapies, namely chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies, have recently transformed the treatment landscape of FL. Two CAR T cell products, axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel), and one bispecific antibody, mosunetuzumab, recently received FDA approvals in FL. Several other new immune effector drugs are being evaluated and will expand the treatment armamentarium. This review focuses on CAR T-cell and bispecific antibody therapies, details their safety and efficacy and considers their evolving role in the current treatment landscape of FL.

T-cell phenotype including CD57+ T follicular helper cells in the tumor microenvironment correlate with a poor outcome in follicular lymphoma

T-lymphocytes are prevalent in the tumor microenvironment of follicular lymphoma (FL). However, the phenotype of T-cells may vary, and the prevalence of certain T-cell subsets may influence tumor biology and patient survival. We therefore analyzed a cohort of 82 FL patients using CyTOF to determine whether specific T-cell phenotypes were associated with distinct tumor microenvironments and patient outcome. We identified four immune subgroups with differing T-cell phenotypes and the prevalence of certain T-cell subsets was associated with patient survival. Patients with increased T cells with early differentiation stage tended to have a significantly better survival than patients with increased T-cells of late differentiation stage. Specifically, CD57+ TFH cells, with a late-stage differentiation phenotype, were significantly more abundant in FL patients who had early disease progression and therefore correlated with an inferior survival. Single cell analysis (CITE-seq) revealed that CD57+ TFH cells exhibited a substantially different transcriptome from CD57- TFH cells with upregulation of inflammatory pathways, evidence of immune exhaustion and susceptibility to apoptosis. Taken together, our results show that different tumor microenvironments among FL patients are associated with variable T-cell phenotypes and an increased prevalence of CD57+ TFH cells is associated with poor patient survival.

Ki67 proliferation index in follicular lymphoma is associated with favorable outcome in patients treated with R-CHOP

Follicular lymphoma (FL) is a common, indolent small B-cell lymphoma. While the Follicular Lymphoma International Prognostic Index is widely used, reliable prognostic and predictive biomarkers are needed. A recent study suggested that architectural patterns of CD10, BCL6, and Ki67 expression may correlate with progression-free survival (PFS) in FL patients treated with chemotherapy-free regimens. We examined the prognostic and predictive utility of architectural patterns of CD10, BCL6, Ki67, and FOXP1 in 90 patients treated with immunochemotherapy (bendamustine-rituximab [BR] and R-cyclophosphamide, doxorubicin, vincristine, prednisone [CHOP]). We found that high follicular Ki67 (≥30%) was associated with longer PFS in the subgroup of patients treated with R-CHOP but not among those treated with BR. Validation of this biomarker may support routine use of Ki67 as a predictive marker in FL.

Interim Positron Emission Tomography During Frontline Chemoimmunotherapy for Follicular Lymphoma

While most patients with follicular lymphoma (FL) have excellent outcomes with frontline chemoimmunotherapy (CIT), a subset of patients will experience early progression, which is associated with poor subsequent outcomes. Novel biomarkers are needed to identify high-risk patients earlier. We hypothesized that interim positron emission tomography (PET) would predict progression-free survival (PFS) in this population. We retrospectively identified 128 patients with grade 1-3A FL who had an interim PET after 2-4 cycles of frontline CIT at 2 academic centers. PET scans were analyzed using Deauville score (DS) and change in maximum standardized uptake value (ΔSUVmax). Interim PET DS was a significant predictor of PFS (P < 0.003). Patients with a DS of 3 had outcomes similar to those of patients with a DS of 4, so were categorized as PET-positive for additional analyses. Interim PET remained a strong predictor of PFS (DS 3-5, hazard ratio [HR] 2.4, P = 0.006) in a multivariable analysis and was also an early predictor of both a positive end-of-treatment PET (P < 0.001) and progression of disease within 24 months (POD24) (P = 0.006). An optimal ΔSUVmax cutoff of 75% was selected using the bootstrap method. ΔSUVmax <75% was also a significant predictor of PFS on univariable and multivariable analyses (HR 2.8, P < 0.003). In a separate cohort of 50 patients with high-grade FL, interim PET interpreted using either DS (P < 0.001) or ΔSUVmax75% (P = 0.034) was also a significant predictor of inferior PFS. In conclusion, interim PET is an independent predictor of PFS and may be useful as a tool for response-adapted treatment strategies in FL.

Follicular lymphoma: The long and winding road leading to your cure?

Follicular lymphoma, the most common indolent lymphoma, though highly responsive to therapy is coupled with multiple relapses for the majority of patients. Advances in biologic understanding of molecular events in lymphoma cells and the tumor microenvironment, along with novel cellular and targeted therapies, suggest this may soon change. Here we first review the development of the molecular concepts and classification of follicular lymphoma, along with therapeutic development of treatments based on chemotherapy plus monoclonal antibodies targeting CD20. We then focus on developments over the last decade in further defining follicular lymphoma pathophysiology, leading to targeted therapeutics, as well as novel immunotherapeutic strategies effective against B cell lymphomas including follicular, particularly patients with advanced stage disease. Additional alterations beyond the hallmark t(14;18) translocation are necessary for development of follicular lymphoma. Epigenetic mutations are almost universally identified in follicular lymphoma, most commonly involving histone-lysine N-methyltransferase 2D (KMT2D, the histone acetyltransferases, cAMP response element-binding protein binding protein (CREBBP) and E1A binding protein P300 (EP300) and the histone methyltransferase enhancer of zeste homologue 2 (EZH2). Mutations are also commonly identified in other proliferation/survival pathways such as B-cell receptor, RAS, mTOR and JAK-STAT pathways, as well as immune escape mutations. The host immune response plays a key role as well, based on studies correlating various immune cell subsets and gene expression signatures with outcomes. Over the last decade, many therapeutic options beyond the commonly used bendamustine-rituximab induction regimen have become available or are being investigated. We focus on these newer agents in the relapsed setting. New antibody-based agents include the naked CD19 directed antibody tafasitamab, the CD79b directed antibody drug conjugate (ADC) polatuzumab vedotin and the CD47 directed antibody magrolimab that targets macrophages rather than FL cells directly. Immune modulation by lenalidomide has moved to earlier lines of therapy and in combinations. Several small molecule inhibitors of proliferation signal pathways involving PI3kinase and BTK have activity against FL. Apoptotic pathway modulators also have activity. With increasing recognition of the high rate of epigenetic mutations in FL, HDAC inhibition has a role. More importantly, the EZH2 inhibitor tazemetostat is FDA approved for FL after 2 prior lines of therapy. The most exciting data currently involve immune attack against follicular lymphoma by chimeric antigen receptor T-cells (CART) or bispecific antibody constructs. Given these multiple potentially non-crossreactive mechanisms, studies of rationally designed combination strategies hold the promise of improving outcomes and possibly cure of follicular lymphoma.

Highly multiplexed spatial profiling with CODEX: bioinformatic analysis and application in human disease

Multiplexed imaging, which enables spatial localization of proteins and RNA to cells within tissues, complements existing multi-omic technologies and has deepened our understanding of health and disease. CODEX, a multiplexed single-cell imaging technology, utilizes a microfluidics system that incorporates DNA barcoded antibodies to visualize 50 + cellular markers at the single-cell level. Here, we discuss the latest applications of CODEX to studies of cancer, autoimmunity, and infection as well as current bioinformatics approaches for analysis of multiplexed imaging data from preprocessing to cell segmentation and marker quantification to spatial analysis techniques. We conclude with a commentary on the challenges and future developments for multiplexed spatial profiling.

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.

Biology of follicular lymphoma: insights and windows of clinical opportunity

Follicular lymphoma (FL) is a heterogeneous disease, both clinically and biologically. The biological behavior and development of FL is a culmination of complex multistep processes underpinned by genetic and nongenetic determinants. Epigenetic deregulation through recurrent genetic alterations is now a recognized major biological hallmark of FL, alongside the t(14;18) translocation. In parallel, there is a strong interplay between the lymphoma B cells and the immune microenvironment, with the microenvironment serving as a critical enabler by creating a tumor-supportive niche and modulating the immune response to favor survival of the malignant B cells. A further layer of complexity arises from the biological heterogeneity that occurs between patients and within an individual, both over the course of the disease and at different sites of disease involvement. Altogether, taking the first steps to bridge the understanding of these various biological components and how to evaluate these clinically may aid and inform future strategies, including logical therapeutic interventions, risk stratification, therapy selection, and disease monitoring.

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.

PARP14 is a novel target in STAT6 mutant follicular lymphoma

The variable clinical course of follicular lymphoma (FL) is determined by the molecular heterogeneity of tumor cells and complex interactions within the tumor microenvironment (TME). IL-4 producing follicular helper T cells (TFH) are critical components of the FL TME. Binding of IL-4 to IL-4R on FL cells activates JAK/STAT signaling. We identified STAT6 mutations (STAT6MUT) in 13% of FL (N = 33/258), all clustered within the DNA binding domain. Gene expression data and immunohistochemistry showed upregulation of IL-4/STAT6 target genes in STAT6MUT FL, including CCL17, CCL22, and FCER2 (CD23). Functionally, STAT6MUT was gain-of-function by serial replating phenotype in pre-B CFU assays. Expression of STAT6MUT enhanced IL-4 induced FCER2/CD23, CCL17 and CCL22 expression and was associated with nuclear accumulation of pSTAT6. RNA sequencing identified PARP14 -a transcriptional switch and co-activator of STAT6- among the top differentially upregulated genes in IL-4 stimulated STAT6MUT lymphoma cells and in STAT6MUT primary FL cells. Quantitative chromatin immunoprecipitation (qChIP) demonstrated binding of STAT6MUT but not STAT6WT to the PARP14 promotor. Reporter assays showed increased IL-4 induced transactivation activity of STAT6MUT at the PARP14 promotor, suggesting a self-reinforcing regulatory circuit. Knock-down of PARP14 or PARP-inhibition abrogated the STAT6MUT gain-of-function phenotype. Thus, our results identify PARP14 as a novel therapeutic target in STAT6MUT FL.

Revealing the evolution of the tumor immune microenvironment in follicular lymphoma patients progressing within 24 months using single-cell imaging mass cytometry

Background

Patients with follicular lymphoma (FL) who experience disease progression within 24 months (POD24) have inferior outcomes. The tumor immune microenvironment (TIME) plays a crucial role in pathogenesis and progression of follicular lymphoma (FL). However, TIME evolution during progression of disease within 24 months (POD24) is elusive.

Methods

Spatially resolved and single-cell image mass cytometry with a panel of 36 metal-tagged antibodies was used to quantitatively analyze the TIME structure in 13 paired FLs at diagnosis and POD24.

Results

Follicles and peri-follicular regions were well dissected in structure. Peri-follicular regions represented a barrier for immune infiltration into the follicles. More FL-cells in the peri-follicular regions suffered CD8⁺T cells attacks under simultaneous protection of regulatory T cells (Tregs) and/or macrophages compared with that in the follicles irrespective of POD24. During POD24, increased CD163⁻ macrophages with PD-1 ligand upregulation and decreased CD8⁺T cells with upregulated LAG-3 expression around FL-cells were observed in the follicles. Spatial analyses demonstrated that FL-cells interacted more intimately with macrophages than with Tregs and less with cytotoxic T cells in both peri-follicular regions and follicles during POD24. In comparison, macrophages also cooperated more frequently with Tregs to simultaneously hijack FL-cells, creating an enhanced immunosuppressive environment in both peri-follicular and follicular regions during POD24.

Conclusions

Peri-follicular regions function as a barrier by recruiting both CD8⁺T cells and immunosuppressive cells, protecting follicular FL-cells from immune attack at diagnosis or POD24. FL-cells reside in a more immune-compromised microenvironment and evade immune cell attacks during POD24. Novel immunotherapeutic approaches harnessing LAG-3, macrophages, and Tregs will be empowered to overcome poor outcomes in patients with FL POD24.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-022-01326-z.

Improving the prognostic ability of PET/CT SUVmax to identify follicular lymphoma with early treatment failure

Follicular lymphoma (FL) has a high degree of heterogeneity both clinically and molecularly. Early treatment failure (ETF), progression or relapse within 24 months of frontline immunochemotherapy is associated with a poor prognosis in FL. However, the clinical utility of ETF at diagnosis is limited. The maximum standardized uptake value (SUVmax) is a metabolic parameter for positron emission tomography/computed tomography (PET/CT); nevertheless, the relationship between SUVmax and ETF remains unclear. Thus, identifying early biomarkers that incorporate SUVmax and other clinical correlative variables could be helpful in identifying patients at high risk of ETF. A nomogram consisted of three independent variables, including SUVmax ≥ 12, beta-2 microglobulin > 3 mg/L, and Ki67 > 40%, was established to predict ETF in 127 patients with grade 1, 2, or 3a FL from the First Hospital of Jilin University (training cohort) and was validated using data from the Duke University Medical Center (validation cohort, n=95). The nomogram demonstrated prognostic accuracy in predicting ETF (sensitivity 70.8% and specificity 83.5% in the training cohort; sensitivity 84.2% and specificity 68.4% in the validation cohort). The patients were stratified into three groups: low-, intermediate-, and high-risk. In the training cohort, the corresponding 5-year progression-free survival (PFS) rates were 81.7%, 73.4%, and 34.9%, and the 5-year overall survival (OS) rates were 97.4%, 87.4%, and 62.3%, respectively. In the validation cohort, the 5-year PFS rates were 77.7%, 52.9%, and 34.8%, and the 5-year OS rates were 96.4%, 94.1%, and 73.7%, respectively. This was the first study to use a nomogram with SUVmax to predict ETF in FL to identify a subset of patients who might benefit from individualized targeted therapy.

Molecular Cytogenetic Profiling Reveals Similarities and Differences Between Localized Nodal and Systemic Follicular Lymphomas

Recently, we have developed novel highly promising gene expression (GE) classifiers discriminating localized nodal (LFL) from systemic follicular lymphoma (SFL) with prognostic impact. However, few data are available in LFL especially concerning hotspot genetic alterations that are associated with the pathogenesis and prognosis of SFL. A total of 144 LFL and 527 SFL, enrolled in prospective clinical trials of the German Low Grade Lymphoma Study Group, were analyzed by fluorescence in situ hybridization to detect deletions in chromosomes 1p, 6q, and 17p as well as BCL2 translocations to determine their impact on clinical outcome of LFL patients. The frequency of chromosomal deletions in 1p and 17p was comparable between LFL and SFL, while 6q deletions and BCL2 translocations more frequently occurred in SFL. A higher proportion of 1p deletions was seen in BCL2-translocation–positive LFL, compared with BCL2-translocation–negative LFL. Deletions in chromosomes 1p, 6q, and 17p predicted clinical outcome of patients with SFL in the entire cohort, while only deletions in chromosome 1p retained its negative prognostic impact in R-CHOP–treated SFL. In contrast, no deletions in one of the investigated genetic loci predicted clinical outcome in LFL. Likewise, the presence or absence of BCL2 translocations had no prognostic impact in LFL. Despite representing a genetic portfolio closely resembling SFL, LFL showed some differences in deletion frequencies. BCL2 translocation and 6q deletion frequency differs between LFL and SFL and might contribute to distinct genetic profiles in LFL and SFL.

CD4+/CD57+/CD69+ T lymphocytes and CD14+ dendritic cells accumulate in advanced follicular lymphoma

Follicular lymphoma is the second most frequent non-Hodgkin's lymphoma, accounting for around 20 % of all lymphomas in Western countries. Initially, it behaves indolently, but in time becomes more aggressive and less susceptible to chemotherapy. Multiple features correlate with the survival of the patients and the progression of the disease, such as therapy with rituximab, tumour microenvironment and the intrafollicular proliferation index. Our research was focused on the association of specific components of tumour microenvironment and the tumour behaviour. The presence and the relative percentage of T lymphocytes, follicular dendritic cells, dendritic cells and macrophages was detected by immunohistochemical staining of the antigens specific for certain cell populations. Our results show that T lymphocytes and dendritic cells affect tumour growth, possibly through interactions with tumour cells. Higher patients' ECOG score and the outcome of the disease are associated with the presence of CD14+ dendritic cells in tumour tissue, while the worse overall survival of patients is associated with the increased number of activated helper T lymphocytes that express marker of exhaustion CD57. Taken together, our results suggest that the efficiency of the immune response against follicular lymphoma depends on more than one type of immune cells. Also, we found that the phenotype of these cells, rather than just their number, affects the tumour behaviour and in consequence survival of the patients.

Tumor Microenvironment and Microvascular Density in Follicular Lymphoma

Follicular lymphoma (FL) is a slowly progressive disease and constitutes the second most common non-Hodgkin lymphoma. Biological factors, such as the tumor microenvironment and the host response, are determinants in the outcome of FL but the experimental data about microenvironment and tumor cells in FL are variable and contradictory. In this morphometric study, we analyzed by immunohistochemistry the cellular components of the tumor microenvironment and correlated these data with the microvascular vascular density in three different grades of FL lymph node biopsies, comparing the results to healthy lymph node controls. The results indicated a significant increase in the number of CD68⁺ and CD163⁺ macrophages in all three analyzed FL grades. Tryptase⁺ mast cells resulted in an increase only in grade 1. PDL-1⁺ cells, CD4- and CD8-lymphocytes number results were reduced in FL samples. The higher number of CD34⁺ microvessels in the FL grades 1 and 2 of samples positively correlated with CD68⁺ and CD163⁺ cells, underlining the important angiogenic potential of this subset of macrophages.

Immune Epigenetic Crosstalk Between Malignant B Cells and the Tumor Microenvironment in B Cell Lymphoma

Epigenetic reprogramming is a hallmark of lymphomagenesis, however its role in reshaping the tumor microenvironment is still not well understood. Here we review the most common chromatin modifier mutations in B cell lymphoma and their effect on B cells as well as on T cell landscape. We will also discuss precision therapy strategies to reverse their aberrant signaling by targeting mutated proteins or counterbalance epigenetic mechanisms.

Tazemetostat: a treatment option for relapsed/refractory follicular lymphoma

INTRODUCTION

Follicular lymphoma (FL) is the second most common form of B cell lymphoma and generally presents as an indolent and relatively slow-growing tumor. However, most FLs are incurable with a shortening of subsequent responses. Therefore, novel and more effective treatments are desperately needed. Tazemetostat is a first-in-class, selective, oral inhibitor of EZH2, a lysine methyltransferase that is mutated in about 25% of FL. Tazemetostat has been recently approved for relapsed/refractory FL after two or more lines of therapy in the presence of an EZH2 mutation or independent of an EZH2 mutation in the absence of other options.

AREAS COVERED

Here, the authors provide a review focusing on the molecular mechanisms of EZH2, clinical development of tazemetostat and other EZH2 inhibitors (EZH2i), as single-agent therapy and in combinatorial regimens. Finally, they provide a futuristic look at therapeutic approaches for this disease.

EXPERT OPINION

Tazemetostat monotherapy showed clinically meaningful and durable responses with a favorable toxicity profile, especially in EZH2 mutant lymphoma. Future studies should explore mechanism-based combinatorial regimens to maximize and prolong the anti-lymphoma effect.

PHOENIX rises: Genomic-based therapies for diffuse large B cell lymphoma

The molecular classification of diffuse large B cell lymphoma has paved the way for precision medicine that targets oncogenic driver pathways and actionable mutations. In this issue of Cancer Cell, Wilson et al. execute a massive genomic analysis in order to identify putative molecular signatures linked to a differential response to ibrutinib plus R-CHOP.