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Competing Interests: The authors have no conflicts of interest to disclose.

Although the genomic and immune microenvironmental landscape of follicular lymphoma (FL) has been extensively investigated, little is known about the potential biological differences between stage I and stage III/IV disease. Using next-generation sequencing and immunohistochemistry, 82 FL nodal stage I cases were analyzed and compared with 139 FL stage III/IV nodal cases. Many similarities in mutations, chromosomal copy number aberrations, and microenvironmental cell populations were detected. However, there were also significant differences in microenvironmental and genomic features. CD8+ T cells (P = .02) and STAT6 mutations (false discovery rate [FDR] <0.001) were more frequent in stage I FL. In contrast, programmed cell death protein 1-positive T cells, CD68+/CD163+ macrophages (P < .001), BCL2 translocation (BCL2trl+) (P < .0001), and KMT2D (FDR = 0.003) and CREBBP (FDR = 0.04) mutations were found more frequently in stage III/IV FL. Using clustering, we identified 3 clusters within stage I, and 2 clusters within stage III/IV. The BLC2trl+ stage I cluster was comparable to the BCL2trl+ cluster in stage III/IV. The two BCL2trl- stage I clusters were unique for stage I. One was enriched for CREBBP (95%) and STAT6 (64%) mutations, without BLC6 translocation (BCL6trl), whereas the BCL2trl- stage III/IV cluster contained BCL6trl (64%) with fewer CREBBP (45%) and STAT6 (9%) mutations. The other BCL2trl- stage I cluster was relatively heterogeneous with more copy number aberrations and linker histone mutations. This exploratory study shows that stage I FL is genetically heterogeneous with different underlying oncogenic pathways. Stage I FL BCL2trl- is likely STAT6 driven, whereas BCL2trl- stage III/IV appears to be more BCL6trl driven., (© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

It has been unclear what role metabolism is playing in the pathophysiology of chronic lymphocytic leukemia (CLL). One reason is that the study of CLL metabolism is challenging due to the resting nature of circulating CLL cells. Also, it is not clear if any of the genomic aberrations observed in this disease have any impact on metabolism. Here, we demonstrate that CLL cells in proliferation centers exhibit upregulation of several molecules involved in glycolysis and mitochondrial metabolism. Comparison of CXCR4/CD5 intraclonal cell subpopulations showed that these changes are paralleled by increases in the metabolic activity of the CXCR4 low CD5 high fraction that have recently egressed from the lymph nodes. Notably, anti-IgM stimulation of CLL cells recapitulates many of these metabolic alterations, including increased glucose uptake, increased lactate production, induction of glycolytic enzymes, and increased respiratory reserve. Treatment of CLL cells with inhibitors of B-cell receptor (BCR) signaling blocked these anti-IgM-induced changes in vitro, which was mirrored by decreases in hexokinase 2 expression in CLL cells from ibrutinib-treated patients in vivo. Interestingly, several samples from patients with 17p-deletion manifested increased spontaneous aerobic glycolysis in the unstimulated state suggestive of a BCR-independent metabolic phenotype. We conclude that the proliferative fraction of CLL cells found in lymphoid tissues or the peripheral blood of CLL patients exhibit increased metabolic activity when compared with the bulk CLL-cell population. Although this is due to microenvironmental stimulatory signals such as BCR-engagement in most cases, increases in resting metabolic activity can be observed in cases with 17p-deletion., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the European Hematology Association.)

The synthesis of serine from glucose is a key metabolic pathway supporting cellular proliferation in healthy and malignant cells. Despite this, the role that this aspect of metabolism plays in germinal center biology and pathology is not known. Here, we performed a comprehensive characterization of the role of the serine synthesis pathway in germinal center B cells and lymphomas derived from these cells. We demonstrate that upregulation of a functional serine synthesis pathway is a metabolic hallmark of B cell activation and the germinal center reaction. Inhibition of phosphoglycerate dehydrogenase (PHGDH), the first and rate-limiting enzyme in this pathway, led to defective germinal formation and impaired high-affinity antibody production. In addition, overexpression of enzymes involved in serine synthesis was a characteristic of germinal center B cell-derived lymphomas, with high levels of expression being predictive of reduced overall survival in diffuse large B cell lymphoma. Inhibition of PHGDH induced apoptosis in lymphoma cells, reducing disease progression. These findings establish PHGDH as a critical player in humoral immunity and a clinically relevant target in lymphoma.

In follicular lymphoma, studies addressing the prognostic value of microenvironment-related immunohistochemical markers and tumor cell-related genetic markers have yielded conflicting results, precluding implementation in practice. Therefore, the Lunenburg Lymphoma Biomarker Consortium performed a validation study evaluating published markers. To maximize sensitivity, an end of spectrum design was applied for 122 uniformly immunochemotherapy-treated follicular lymphoma patients retrieved from international trials and registries. The criteria were: early failure, progression or lymphoma-related death <2 years versus long remission, response duration of >5 years. Immunohistochemical staining for T cells and macrophages was performed on tissue microarrays from initial biopsies and scored with a validated computer-assisted protocol. Shallow whole-genome and deep targeted sequencing was performed on the same samples. The 96/122 cases with complete molecular and immunohistochemical data were included in the analysis. EZH2 wild-type ( P =0.006), gain of chromosome 18 ( P =0.002), low percentages of CD8+ cells ( P =0.011) and CD163+ areas ( P =0.038) were associated with early failure. No significant differences in other markers were observed, thereby refuting previous claims of their prognostic significance. Using an optimized study design, this Lunenburg Lymphoma Biomarker Consortium study substantiates wild-type EZH2 status, gain of chromosome 18, low percentages of CD8+ cells and CD163+ area as predictors of early failure to immunochemotherapy in follicular lymphoma treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP [-like]), while refuting the prognostic impact of various other markers., (Copyright© 2017 Ferrata Storti Foundation.)

Blockade of the programmed cell death 1 (PD-1)/programmed death-ligand 1 (PD-L1) immune checkpoint augments antitumor immunity and induces durable responses in patients with solid cancers, but data on clinical efficacy in leukemias are sparse. Chronic lymphocytic leukemia (CLL) is associated with a tumor-supportive microenvironment and a dysfunctional immune system, as shown by "exhausted" T cells, defective immunologic synapse formation, and immunosuppressive myeloid cells. These defects involve aberrant expression of PD-L1 and are closely mirrored in the Eµ-TCL1 mouse model for CLL. In this study, we treated mice after adoptive transfer of Eµ-TCL1 CLL with PD-L1-blocking antibodies, which prevented CLL development and was accompanied by a reactivation of immune effector functions. This included restoration of mature macrophages and major histocompatibility complex class II-expressing dendritic cells and prevention of aberrant and exhaustion-like T-cell phenotypes. In addition, PD-L1 blockade restored CD8 T-cell cytotoxicity and immune synapse formation and normalized T-cell cytokines and proliferation ex vivo and in vivo. Our data demonstrate that early PD-L1 blockade effectively corrects leukemia-induced immune dysfunction and thus prevents CLL development in mice. Targeting PD-L1/PD-1 interactions should therefore be further explored in clinical studies with CLL patients, ideally in combination with novel compounds to help eliminate CLL., (© 2015 by The American Society of Hematology.)

Gene expression studies have identified the microenvironment as a prognostic player in diffuse large B-cell lymphoma. However, there is a lack of simple immune biomarkers that can be applied in the clinical setting and could be helpful in stratifying patients. Immunohistochemistry has been used for this purpose but the results are inconsistent. We decided to reinvestigate the immune microenvironment and its impact using immunohistochemistry, with two systems of image analysis, in a large set of patients with diffuse large B-cell lymphoma. Diagnostic tissue from 309 patients was arrayed onto tissue microarrays. Results from 161 chemoimmunotherapy-treated patients were used for outcome prediction. Positive cells, percentage stained area and numbers of pixels/area were quantified and results were compared with the purpose of inferring consistency between the two semi-automated systems. Measurement cutpoints were assessed using a recursive partitioning algorithm classifying results according to survival. Kaplan-Meier estimators and Fisher exact tests were evaluated to check for significant differences between measurement classes, and for dependence between pairs of measurements, respectively. Results were validated by multivariate analysis incorporating the International Prognostic Index. The concordance between the two systems of image analysis was surprisingly high, supporting their applicability for immunohistochemistry studies. Patients with a high density of CD3 and FoxP3 by both methods had a better outcome. Automated analysis should be the preferred method for immunohistochemistry studies. Following the use of two methods of semi-automated analysis we suggest that CD3 and FoxP3 play a role in predicting response to chemoimmunotherapy in diffuse large B-cell lymphoma., (Copyright© Ferrata Storti Foundation.)

The leukocyte adhesion cascade is important in chronic lymphocytic leukemia (CLL), as it controls migration of malignant cells into the pro-survival lymph node microenvironment. Circulating trisomy 12 CLL cells have increased expression of the integrins CD11a and CD49d, as well as CD38, but the tissue expression of these and other molecules, and the functional and clinical sequelae of these changes have not been described. Here, we demonstrate that circulating trisomy 12 CLL cells also have increased expression of the integrins CD11b, CD18, CD29, and ITGB7, and the adhesion molecule CD323. Notably, there was reduced expression of CD11a, CD11b, and CD18 in trisomy 12 cases with NOTCH1 mutations compared with wild type. Trisomy 12 cells also exhibit upregulation of intracellular integrin signaling molecules CALDAG-GEFI, RAP1B, and Ras-related protein ligand, resulting in enhanced very late antigen-4 [VLA-4] directed adhesion and motility. CD38 expression in CLL has prognostic significance, but the increased CD38 expression in trisomy 12 CLL cells must be taken into account in this subgroup, and the threshold of CD38 positivity should be raised to 40% for this marker to retain its prognostic value. In conclusion, trisomy 12 CLL cells exhibit functional upregulation of integrin signaling, with β2-integrin expression being modulated by NOTCH1 mutation status., (© 2014 by The American Society of Hematology.)

Purpose: The opportunity to improve therapeutic choices on the basis of molecular features of the tumor cells is on the horizon in diffuse large B-cell lymphoma (DLBCL). Agents such as bortezomib exhibit selective activity against the poor outcome activated B-cell type (ABC) DLBCL. In order for targeted therapies to succeed in this disease, robust strategies that segregate patients into molecular groups with high reliability are needed. Although molecular studies are considered gold standard, several immunohistochemistry (IHC) algorithms have been published that claim to be able to stratify patients according to their cell-of-origin and to be relevant for patient outcome. However, results are poorly reproducible by independent groups., Experimental Design: We investigated nine IHC algorithms for molecular classification in a dataset of DLBCL diagnostic biopsies, incorporating immunostaining for CD10, BCL6, BCL2, MUM1, FOXP1, GCET1, and LMO2. IHC profiles were assessed and agreed among three expert observers. A consensus matrix based on all scoring combinations and the number of subjects for each combination allowed us to assess reliability. The survival impact of individual markers and classifiers was evaluated using Kaplan-Meier curves and the log-rank test., Results: The concordance in patient's classification across the different algorithms was low. Only 4% of the tumors have been classified as germinal center B-cell type (GCB) and 21% as ABC/non-GCB by all methods. None of the algorithms provided prognostic information in the R-CHOP (rituximab plus cyclophosphamide-adriamycin-vincristine-prednisone)-treated cohort., Conclusion: Further work is required to standardize IHC algorithms for DLBCL cell-of-origin classification for these to be considered reliable alternatives to molecular-based methods to be used for clinical decisions., (©2013 AACR.)

Background & Aims: Pancreatic ductal adenocarcinoma (PDAC) is characterized by a prominent desmoplastic microenvironment that contains many different immune cells. Activated pancreatic stellate cells (PSCs) contribute to the desmoplasia. We investigated whether distinct stromal compartments are differentially infiltrated by different types of immune cells., Methods: We used tissue microarray analysis to compare immune cell infiltration of different pancreaticobiliary diseased tissues (PDAC, ampullary carcinoma, cholangiocarcinoma, mucinous cystic neoplasm, chronic inflammation, and chronic pancreatitis) and juxtatumoral stromal (<100 μm from tumor) and panstromal compartments. We investigated the association between immune infiltrate and patient survival times. We also analyzed T-cell migration and tumor infiltration in LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mice and the effects of all-trans retinoic acid (ATRA) on these processes., Results: Juxtatumoral compartments in PDAC samples from 2 independent groups of patients contained increased numbers of myeloperoxidase(+) and CD68(+) cells compared with panstromal compartments. However, juxtatumoral compartments of PDACs contained fewer CD8(+), FoxP3(+), CD56(+), or CD20(+) cells than panstromal compartments, a distinction absent in ampullary carcinomas and cholangiocarcinomas. Patients with PDACs that had high densities of CD8(+) T cells in the juxtatumoral compartment had longer survival times than patients with lower densities. In KPC mice, administration of ATRA, which renders PSCs quiescent, increased numbers of CD8(+) T cells in juxtatumoral compartments. We found that activated PSCs express cytokines, chemokines, and adhesion molecules that regulate T-cell migration. In vitro migration assays showed that CD8(+) T cells, from patients with PDAC, had increased chemotaxis toward activated PSCs, which secrete CXCL12, compared with quiescent PSCs or tumor cells. These effects could be reversed by knockdown of CXCL12 or treatment of PSCs with ATRA., Conclusions: Based on studies of human PDAC samples and KPC mice, activated PSCs appear to reduce migration of CD8(+) T cells to juxtatumoral stromal compartments, preventing their access to cancer cells. Deregulated signaling by activated PSCs could prevent an effective antitumor immune response., (Copyright © 2013 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Cancer immune evasion is an emerging hallmark of disease progression. We have demonstrated previously that impaired actin polymerization at the T-cell immunologic synapse is a global immune dysfunction in chronic lymphocytic leukemia (CLL). Direct contact with tumor cells induces defective actin polarization at the synapse in previously healthy T cells, but the molecules mediating this dysfunction were not known. In the present study, we show via functional screening assays that CD200, CD270, CD274, and CD276 are coopted by CLL cells to induce impaired actin synapse formation in both allogeneic and autologous T cells. We also show that inhibitory ligand-induced impairment of T-cell actin dynamics is a common immunosuppressive strategy used by both hematologic (including lymphoma) and solid carcinoma cells. This immunosuppressive signaling targets T-cell Rho-GTPase activation. Of clinical relevance, the immunomodulatory drug lenalidomide prevented the induction of these defects by down-regulating tumor cell-inhibitory molecule expression. These results using human CLL as a model cancer establish a novel evasion mechanism whereby malignant cells exploit multiple inhibitory ligand signaling to down-regulate small GTPases and lytic synapse function in global T-cell populations. These findings should contribute to the design of immunotherapeutic strategies to reverse T-cell tolerance in cancer.

Follicular lymphoma has considerable clinical heterogeneity, and there is a need for easily quantifiable prognostic biomarkers. Microvessel density has been shown to be a useful prognostic factor based on numerical assessment of vessel numbers within histologic sections in some studies, but assessment of tumor neovascularization through angiogenic sprouting may be more relevant. We therefore examined the smallest vessels, single-staining structures measuring less than 30 microm(2) in area, seen within histologic sections, and confirmed that they were neovascular angiogenic sprouts using extended focal imaging. Tissue microarrays composing diagnostic biopsies from patients at the extremes of survival of follicular lymphoma were analyzed with respect to numbers of these sprouts. This analysis revealed higher angiogenic activity in the poor prognostic group and demonstrated an association between increased sprouting and elevated numbers of infiltrating CD163(+) macrophages within the immediate microenvironment surrounding the neovascular sprout.

An important hallmark of cancer progression is the ability of tumor cells to evade immune recognition. Understanding the relationship between neoplastic cells and the immune microenvironment should facilitate the design of improved immunotherapies. Here we identify impaired T-cell immunologic synapse formation as an active immunosuppressive mechanism in follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL). We found a significant reduction in formation of the F-actin immune synapse in tumor-infiltrating T cells (P < .01) from lymphoma patients compared with age-matched healthy donor cells. Peripheral blood T cells exhibited this defect only in patients with leukemic-phase disease. Moreover, we demonstrate that this T-cell defect is induced after short-term tumor cell contact. After 24-hour coculture with FL cells, previously healthy T cells showed suppressed recruitment of critical signaling proteins to the synapse. We further demonstrate repair of this defect after treatment of both FL cells and T cells with the immunomodulatory drug lenalidomide. Tissue microarray analysis identified reduced expression of the T-cell synapse signature proteins, including the cytolytic effector molecule Rab27A associated with poor prognosis, in addition to reduced T-cell numbers and activity with disease transformation. Our results highlight the importance of identifying biomarkers and immunotherapeutic treatments for repairing T-cell responses in lymphoma.

The role of TP53 mutation in transformation of follicular lymphoma (FL) to diffuse large B-cell lymphoma (t-FL) was examined in a panel of 91 lymph node biopsies derived from 29 patients pre- and post-transformation. The entire TP53 coding sequence was screened and immunocytochemistry performed to determine expression of p53 and its key regulator MDM2. A total of 10 mutations were detected in eight patients (28%), although none were present at FL diagnosis. Mutations were not detected solely at the time of transformation; in three patients, mutated TP53 arose in at least one antecedent FL sample (6 months, 2.5 years and 4 years prior to transformation). Loss of heterozygosity at the TP53 locus occurred in 2/20 informative patients (only in t-FL samples). p53 staining was positive in 82% (9/11) of available biopsies with a missense mutation, and negative in 71% (45/63) with wtTP53. MDM2 expression was significantly higher in t-FL samples (mean 72% positive; 95% confidence interval (95% CI) 68-76%) than FL (mean 58% positive; 95% CI 54-62%) (P<0.001) but did not correlate with TP53 status. TP53 mutation has only a limited role in the transformation of FL, exerting a heterogeneous influence upon phenotypic change. In contrast, dysregulation of MDM2 is frequent and may provide a more rational therapeutic target.., (Leukemia (2005) 19, 1459-1465.)