The classical Hodgkin lymphoma tumor microenvironment: macrophages and gene expression-based modeling

Spatially Resolved Tumor Microenvironment Predicts Treatment Outcomes in Relapsed/Refractory Hodgkin Lymphoma

PURPOSE

About a third of patients with relapsed or refractory classic Hodgkin lymphoma (r/r CHL) succumb to their disease after high-dose chemotherapy followed by autologous stem-cell transplantation (HDC/ASCT). Here, we aimed to describe spatially resolved tumor microenvironment (TME) ecosystems to establish novel biomarkers associated with treatment failure in r/r CHL.

PATIENTS AND METHODS

We performed imaging mass cytometry (IMC) on 71 paired primary diagnostic and relapse biopsies using a marker panel specific to CHL biology. For each cell type in the TME, we calculated a spatial score measuring the distance of nearest neighbor cells to the malignant Hodgkin Reed Sternberg cells within the close interaction range. Spatial scores were used as features in prognostic model development for post-ASCT outcomes.

RESULTS

Highly multiplexed IMC data revealed shared TME patterns in paired diagnostic and early r/r CHL samples, whereas TME patterns were more divergent in pairs of diagnostic and late relapse samples. Integrated analysis of IMC and single-cell RNA sequencing data identified unique architecture defined by CXCR5+ Hodgkin and Reed Sternberg (HRS) cells and their strong spatial relationship with CXCL13+ macrophages in the TME. We developed a prognostic assay (RHL4S) using four spatially resolved parameters, CXCR5+ HRS cells, PD1+CD4+ T cells, CD68+ tumor-associated macrophages, and CXCR5+ B cells, which effectively separated patients into high-risk versus low-risk groups with significantly different post-ASCT outcomes. The RHL4S assay was validated in an independent r/r CHL cohort using a multicolor immunofluorescence assay.

CONCLUSION

We identified the interaction of CXCR5+ HRS cells with ligand-expressing CXCL13+ macrophages as a prominent crosstalk axis in relapsed CHL. Harnessing this TME biology, we developed a novel prognostic model applicable to r/r CHL biopsies, RHL4S, opening new avenues for spatial biomarker development.

Prognostic Markers within the Tumour Microenvironment in Classical Hodgkin Lymphoma

Classical Hodgkin lymphoma (cHL) accounts for 0.4% of all new cancer cases globally. Despite high cure rates with standard treatment, approximately 15% of patients still experience relapsed or refractory (RR) disease, and many of these eventually die from lymphoma-related causes. Exciting new targeted agents such as anti-PD-1 agents and brentuximab vedotin have changed the therapeutic paradigm beyond chemotherapy and radiotherapy alone. Advances in understanding of the molecular biology are providing insights in the context of novel therapies. The signature histology of cHL requires the presence of scant malignant Hodgkin Reed-Sternberg cells (HRSCs) surrounded by a complex immune-rich tumour microenvironment (TME). The TME cellular composition strongly influences outcomes, yet knowledge of the precise characteristics of TME cells and their interactions with HRSCs is evolving. Novel high-throughput technologies and single-cell sequencing allow deeper analyses of the TME and mechanisms elicited by HRSCs to propagate growth and avoid immune response. In this review, we explore the evolution of knowledge on the prognostic role of immune cells within the TME and provide an up-to-date overview of emerging prognostic data on cHL from new technologies that are starting to unwind the complexity of the cHL TME and provide translational insights into how to improve therapy in the clinic.

Targeting tumour-associated macrophages in hodgkin lymphoma using engineered extracellular matrix-mimicking cryogels

Tumour-associated macrophages are linked with poor prognosis and resistance to therapy in Hodgkin lymphoma; however, there are no suitable preclinical models to identify macrophage-targeting therapeutics. We used primary human tumours to guide the development of a mimetic cryogel, wherein Hodgkin (but not Non-Hodgkin) lymphoma cells promoted primary human macrophage invasion. In an invasion inhibitor screen, we identified five drug hits that significantly reduced tumour-associated macrophage invasion: marimastat, batimastat, AS1517499, ruxolitinib, and PD-169316. Importantly, ruxolitinib has demonstrated recent success in Hodgkin lymphoma clinical trials. Both ruxolitinib and PD-169316 (a p38 mitogen-activated protein kinase (p38 MAPK) inhibitor) decreased the percent of M2-like macrophages; however, only PD-169316 enhanced the percentage of M1-like macrophages. We validated p38 MAPK as an anti-invasion drug target with five additional drugs using a high-content imaging platform. With our biomimetic cryogel, we modeled macrophage invasion in Hodgkin lymphoma and then used it for target discovery and drug screening, ultimately identifying potential future therapeutics.

Tumor Immune Microenvironment Components and Checkpoint Molecules in Anaplastic Variant of Diffuse Large B-Cell Lymphoma

Background

Anaplastic diffuse large B-cell lymphoma(A-DLBCL) is a rare morphological subtype characterized by the presence of polygonal, bizarre-shaped tumor cells. Our previous research found that A-DLBCL displays many genetic alterations and biological features that differ greatly from those of ordinary DLBCL. However, the status of tumor immune microenvironment components and checkpoint molecules in A-DLBCL remains unclear.

Methods

Thirty A-DLBCL patients were enrolled to study tumor immune microenvironment components and checkpoint molecules and their associations with clinicopathological features and prognosis.

Results

Patients with A-DLBCL presented higher expression of PD-L1 (40% vs 10%, P=0.004) than patients with ordinary DLBCL. FISH analysis showed that extra copies of PD-L1 were more frequent in A-DLBCL cases than in ordinary DLBCL cases (23.3% vs 4.0%, P=0.001). The numbers of PD-1⁺ TILs (tumor infiltrating lymphocytes) and CD8⁺T cells were significantly lower in A-DLBCL versus ordinary DLBCL. In contrast, the numbers of GATA3⁺ Th2 cells, FOXP3⁺ Tregs and CD33⁺ myeloid-derived suppressor cells (MDSCs) were significantly higher in A-DLBCL than in ordinary DLBCL. The associations between clinicopathological features and tumor immune microenvironment cell frequency were analyzed in A-DLBCL patients. Briefly, the number of PD-1⁺ TILs was lower and the number of CD33⁺ MDSCs was higher in patients with mutated TP53 compared to those with wild-type TP53. The number of FOXP3⁺ Tregs was much lower in patients with a noncomplete response (CR) to chemotherapy than in those with a complete response. The number of CD8⁺ T cells showed a decreasing trend in patients with high International Prognostic Index (IPI) scores and in those with concurrent MYC and BCL2 and/or BCL6 abnormalities. Univariate survival analysis showed that patients with PD-L1⁺, mPD-L1⁺(PD-L1⁺ nonmalignant stromal cells) or mPD-L1⁺ status had a significantly poorer overall survival (OS) than those with PD-L1^- status. An increase in the number of CD3⁺ T cells, FOXP3⁺ Treg cells and T-bet⁺ Th1 cells was significantly associated with prolonged OS in patients with A-DLBCL.

Conclusion

Our study suggests that A-DLBCL displays a distinct pattern of tumor immune microenvironment components and checkpoint molecules that distinguish it from ordinary DLBCL. The analysis of tumor immune microenvironment components and checkpoint molecules could help in predicting the prognosis of A-DLBCL patients and determining therapeutic strategies targeting the tumor immune microenvironment.

Positron Emission Tomography Imaging of Macrophages in Cancer

Macrophages are large phagocytic cells that can be classified as a type of white blood cell and may be either mobile or stationary in tissues. The presence of macrophages in essentially every major disease makes them attractive candidates to serve as therapeutic targets and diagnostic biomarkers. Macrophages that are found in the microenvironment of solid tumors are referred to as tumor-associated macrophages (TAMs) and have been shown to influence chemoresistance, immune regulation, tumor initiation and tumor growth. The imaging of TAMs through Positron Emission Tomography (PET) has the potential to provide valuable information on cancer biology, tumor progression, and response to therapy. This review will highlight the versatility of macrophage imaging in cancer through the use of PET.

Clinical relevance of NKT cells and soluble MIC-A in Hodgkin lymphoma

Previous studies demonstrated that the majority of Hodgkin lymphoma (HL) patients achieve response after treatment, while 5% become refractory. Studies analyzing the role of lymphocyte subsets in peripheral blood are limited. This investigation sought to evaluate peripheral blood lymphocyte subsets and soluble MHC class I chain-related proteins A and B (sMIC-A/B) and their correlation with survival in patients with newly diagnosed HL. The study recruited 36 patients and 72 healthy donors. HL patients showed a decrease in CD4, B, monocytes, NK, and NKT cells; and an increase in γ-δ T cells and soluble MIC-A serum levels. Higher values of s-MIC-A  >100 ng/mL and NKT cells >40 µL correlated with poor overall survival (OS). In conclusion, in HL peripheral blood CD4 T and B cells, monocytes, NK, and NKT cells were decreased, while s-MIC-A and γ-δ T cells increased. Higher values of s-MIC-A and NKT cells correlated with poor survival.

[Microenvironment in classical Hodgkin lymphoma]

Classical Hodgkin lymphoma (cHL) is histologically characterized by a quantitatively dominating immune cell infiltrate. Its composition differs depending on the histological subtype and EBV (Epstein-Barr-Virus) status. Current pathogenic concepts postulate that the malignant cells, the so-called Hodgkin and Reed-Sternberg (HRS) cells, act as master recruiters, thereby actively shaping the microenvironment to support their proliferation and outgrowth. This view on the pathogenesis of cHL is further solidified by genetic studies, which have identified important mechanisms by which the HRS cells are enabled to escape immune surveillance. Besides an insufficient antigen presentation mediated by mutations and structural chromosomal changes in key components or regulators of major histocompatibility class I and II molecules, copy number gains of the 9p24.1 genomic locus encompassing JAK2 and the ligands of the programmed cell death protein 1 (PD-1), PD-L1 and PD-L2, play an important role in the pathogenesis of this disease as the engagement of those ligands with their cognate receptor leads to suppression of the immune response. Of importance, the reversibility of this inhibitory receptor-ligand interaction is key to the clinical success that checkpoint inhibitors had and continue to have in cHL patients, especially in the relapse setting. In addition, comprehensive assessment of microenvironment composition, integration with results from genetic studies, and correlation with clinical outcomes have led to the development of prognostic models, which may assist in an improved risk stratification, informed selection of treatment regimens, and therefore better outcomes.

Prognostic Impact of Tumor-Associated Macrophages on Survival Is Checkpoint Dependent in Classical Hodgkin Lymphoma

Tumor microenvironment and immune escape affect pathogenesis and survival in classical Hodgkin lymphoma (cHL). While tumor-associated macrophage (TAM) content has been associated with poor outcomes, macrophage-derived determinants with clinical impact have remained undefined. Here, we have used multiplex immunohistochemistry and digital image analysis to characterize TAM immunophenotypes with regard to expression of checkpoint molecules programmed cell death ligand 1 (PD-L1) and indoleamine 2,3-dioxygenase 1 (IDO-1) from the diagnostic tumor tissue samples of 130 cHL patients, and correlated the findings with clinical characteristics and survival. We show that a large proportion of TAMs express PD-L1 (CD68⁺, median 32%; M2 type CD163⁺, median 22%), whereas the proportion of TAMs expressing IDO-1 is lower (CD68⁺, median 5.5%; CD163⁺, median 1.4%). A high proportion of PD-L1 and IDO-1 expressing TAMs from all TAMs (CD68⁺), or from CD163⁺ TAMs, is associated with inferior outcome. In multivariate analysis with age and stage, high proportions of PD-L1⁺ and IDO-1⁺ TAMs remain independent prognostic factors for freedom from treatment failure (PD-L1⁺CD68⁺/CD68⁺, HR = 2.63, 95% CI 1.17–5.88, p = 0.019; IDO-1⁺CD68⁺/CD68⁺, HR = 2.48, 95% CI 1.03–5.95, p = 0.042). In contrast, proportions of PD-L1⁺ tumor cells, all TAMs or PD-L1⁻ and IDO-1⁻ TAMs are not associated with outcome. The findings implicate that adverse prognostic impact of TAMs is checkpoint-dependent in cHL.

High CD206 levels in Hodgkin lymphoma-educated macrophages are linked to matrix-remodeling and lymphoma dissemination

Macrophages (Mφ) are abundantly present in the tumor microenvironment and may predict outcome in solid tumors and defined lymphoma subtypes. Mφ heterogeneity, the mechanisms of their recruitment, and their differentiation into lymphoma‐promoting, alternatively activated M2‐like phenotypes are still not fully understood. Therefore, further functional studies are required to understand biological mechanisms associated with human tumor‐associated Mφ (TAM). Here, we show that the global mRNA expression and protein abundance of human Mφ differentiated in Hodgkin lymphoma (HL)‐conditioned medium (CM) differ from those of Mφ educated by conditioned media from diffuse large B‐cell lymphoma (DLBCL) cells or, classically, by macrophage colony‐stimulating factor (M‐CSF). Conditioned media from HL cells support TAM differentiation through upregulation of surface antigens such as CD40, CD163, CD206, and PD‐L1. In particular, RNA and cell surface protein expression of mannose receptor 1 (MRC1)/CD206 significantly exceed the levels induced by classical M‐CSF stimulation in M2‐like Mφ; this is regulated by interleukin 13 to a large extent. Functionally, high CD206 enhances mannose‐dependent endocytosis and uptake of type I collagen. Together with high matrix metalloprotease9 secretion, HL‐TAMs appear to be active modulators of the tumor matrix. Preclinical in ovo models show that co‐cultures of HL cells with monocytes or Mφ support dissemination of lymphoma cells via lymphatic vessels, while tumor size and vessel destruction are decreased in comparison with lymphoma‐only tumors. Immunohistology of human HL tissues reveals a fraction of cases feature large numbers of CD206‐positive cells, with high MRC1 expression being characteristic of HL‐stage IV. In summary, the lymphoma‐TAM interaction contributes to matrix‐remodeling and lymphoma cell dissemination.

Inhibition of MDR1 Overcomes Resistance to Brentuximab Vedotin in Hodgkin Lymphoma

PURPOSE

In classical Hodgkin lymphoma, the malignant Reed-Sternberg cells express the cell surface marker CD30. Brentuximab vedotin is an antibody-drug conjugate (ADC) that selectively delivers a potent cytotoxic agent, monomethyl auristatin E (MMAE), to CD30-positive cells. Although brentuximab vedotin elicits a high response rate (75%) in relapsed/refractory Hodgkin lymphoma, most patients who respond to brentuximab vedotin eventually develop resistance.

PATIENTS AND METHODS

We developed two brentuximab vedotin-resistant Hodgkin lymphoma cell line models using a pulsatile approach and observed that resistance to brentuximab vedotin is associated with an upregulation of multidrug resistance-1 (MDR1). We then conducted a phase I trial combining brentuximab vedotin and cyclosporine A (CsA) in patients with relapsed/refractory Hodgkin lymphoma.

RESULTS

Here, we show that competitive inhibition of MDR1 restored sensitivity to brentuximab vedotin in our brentuximab vedotin-resistant cell lines by increasing intracellular MMAE levels, and potentiated brentuximab vedotin activity in brentuximab vedotin-resistant Hodgkin lymphoma tumors in a human xenograft mouse model. In our phase I trial, the combination of brentuximab vedotin and CsA was tolerable and produced an overall and complete response rate of 75% and 42% in a population of patients who were nearly all refractory to brentuximab vedotin.

CONCLUSIONS

This study may provide a new therapeutic strategy to combat brentuximab vedotin resistance in Hodgkin lymphoma. This is the first study reporting an effect of multidrug resistance modulation on the therapeutic activity of an ADC in humans. The expansion phase of the trial is ongoing and enrolling patients who are refractory to brentuximab vedotin to confirm clinical activity in this population with unmet need.

Identification of a novel monocytic phenotype in Classic Hodgkin Lymphoma tumor microenvironment

Classic Hodgkin lymphoma (CHL) characteristically shows few malignant cells in a microenvironment comprised of mixed inflammatory cells. Although CHL is associated with a high cure rate, recent studies have associated poor prognosis with absolute monocyte count in peripheral blood and increased monocyte/macrophages in involved lymph nodes. Thus, the role of monocytic infiltration and macrophage differentiation in the tumor microenvironment of CHL may be more relevant than absolute macrophage numbers to defining prognosis in CHL patients and potentially have therapeutic implications. Most studies identify tumor-associated macrophages (TAMs) using markers (e.g., CD68) expressed by macrophages and other mononuclear phagocytes, such as monocytes. In contrast, Class A Scavenger Receptor (SR-A/CD204) is expressed by tissue macrophages but not monocytic precursors. In this study, we examined SR-A expression in CHL (n = 43), and compared its expression with that of other macrophage markers. We confirmed a high prevalence of mononuclear cells that stained with CD68, CD163, and CD14 in CHL lymph nodes. However, SR-A protein expression determined by immunohistochemistry was limited to macrophages localized in sclerotic bands characteristic of nodular sclerosis CHL. In contrast, SR-A protein was readily detectable in lymph nodes with metastatic tumor, extra-nodal CHL, T cell/histiocyte-rich large B cell lymphoma, and resident macrophages in non-malignant tissues, including spleen, lymph node, liver and lung. The results of SR-A protein expression paralleled the expression of SR-A mRNA determined by quantitative RT-PCR. These data provide evidence that tumor-infiltrating monocyte/macrophages in CHL have a unique phenotype that likely depends on the microenvironment of nodal CHL.

Differing reflections of paediatric classical Hodgkin's lymphoma on local and distant immunological microenvironments: a flow cytometric study

AIMS

To compare immunological microenvironments in local and distant lymphoid tissues in Hodgkin's lymphoma (HL) in children.

METHODS

We have analysed diagnostic bone marrow (BM) samples in 22 and corresponding involved lymph node (LN) in eight and peripheral blood (PB) in eight cases of HL by flow cytometry and sought correlations with clinical features retrospectively.

RESULTS

While there were significant differences in lymphocyte compositions of BM and LN tissues, the distribution of lymphocyte subsets mimicked each other in BM and PB. CD8-positive cytotoxic T cells predominate the bone marrow in contrast to CD4-positive helper T cells in LN tissue with corresponding CD4/CD8 ratios (0.85 and 5.3, respectively; p=0.002). Additionally, T-large granular lymphocytes population was much higher in BM in comparison to LN tissue (10.5% vs 4.5%; p=0.036).

CONCLUSIONS

Local immunological microenvironment appears to be highly influenced by HL tumour cells and distant site lymphocyte composition reflects immune response to control the neoplastic process.

CD163 is a predictive biomarker for prognosis of classical Hodgkin's lymphoma in Saudi patients

Hodgkin's lymphoma (HL) is a hematological malignancy characterized by a minority of neoplastic cells outnumbered by tumor-associated macrophages (TAMs). The overexpression of the CD163 antigen by TAMs is considered to be a significant predictive biomarker for risk stratification. This is likely caused by a genetic single-nucleotide polymorphism (SNP) at the gene promoter. The aim of the present retrospective case-control study was to establish a gene expression profile of a specific biomarker for classical HL (CHL) in order to predict the outcome and survival of CHL patients in Saudi Arabia. The protein expression of CD163 on TAMs was studied using immunohistochemistry (IHC). A prognosis index was calculated for the CD163 protein to assess the risk stratification of CHL. Genotyping of selected SNPs of this antigen was performed for 100 CHL cases and controls. The analysis revealed that the CD163 protein expression level was significantly correlated with disease relapse (DR) and overall survival (OS). In addition, the CD163 index threshold (15.0) was found to be significantly correlated with the relapse rate. Among the studied CD163 SNPs, rs75608120 exhibited a significant correlation with the DR rate of CHL patients, but not with OS. The findings of the present study confirmed that CD163 is a specific marker for TAMs, and its overexpression by TAMs is significantly associated with relapse and reduced survival post-therapy. In addition, a new methodology of indexing CD163 protein expression for HL risk stratification was proposed. Thus, the present study identified a specific predictive molecular and antigenic biomarker for CHL prognosis.

Impaired Cytolytic Activity and Loss of Clonal Neoantigens in Elderly Patients With Lung Adenocarcinoma

INTRODUCTION

Whether the efficacy of programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) inhibitors declines with senescence remains controversial for lung adenocarcinoma (LUAD). Responsiveness to anti-PD-1/PD-L1 therapy is thought to rely on neoantigen exposure and immune elements in the tumor microenvironment. In this study, we explored the features of the tumor immune microenvironment in elderly patients with treatment-naïve LUAD.

METHODS

Transcriptome profiles and clinical characteristics of patients with LUAD were retrieved from The Cancer Genome Atlas as a discovery cohort. Immune cell infiltration (quantified by a single-sample gene set enrichment analysis), immunoregulatory molecule expression, and mutational patterns (from The Cancer Immunome Atlas) were compared between young and elderly patients. Immune cell infiltration was verified by immunohistochemistry using a validation cohort including 105 treatment-naïve patients with LUAD. A tissue microarray consisting of 120 LUAD patients was used in the immunohistochemistry validation.

RESULTS

Activated CD8⁺ T cell numbers increased slightly with age, but cytolytic molecules in T cells (granzyme B [GZMB], perforin 1 [PRF1], granzyme A [GZMA], granzyme M [GZMM], and granulysin [GNLY]) gradually declined. PD-L1 expression was not associated with age; however, a number of immunosuppressive elements beyond PD-L1 were upregulated in aging patients, including regulatory T cells and co-inhibitory molecules, for example, TIM-3, TIGIT, and HHLA2. Finally, senescence was accompanied by a loss of clonal neoantigens, which is believed to be correlated with responsiveness to immune checkpoint inhibitors.

CONCLUSIONS

Elderly patients were characterized by increased numbers of CD8⁺ T cells and impaired cytolytic molecule expression. The observed immune signature was also associated with a loss of clonal neoantigens and the accumulation of immunosuppressive elements. These findings show a unique immune microenvironment in senescence and support biomarker-guided candidate identification for anti-PD-1/PD-L1 therapeutic strategies for elderly patients with LUAD.

Overall survival of classical Hodgkins lymphoma in Saudi patients is affected by XPG repair gene polymorphism

In Hodgkin's lymphoma (HL), single nucleotide polymorphisms (SNPs) of specific DNA repair genes have been identified to have an important role in the risk of HL. Consequently, they may also serve an important role in HL prognosis and disease outcome. The present study aimed to define an SNP molecular profile, based on DNA repair genes mutations, as predictive biomarkers for the prognostic outcome of patients with Classical HL (CHL) in Saudi Arabia. Genotyping of selected SNPs located in selected DNA repair genes was performed on 100 CHL cases and an equivalent number of healthy controls. No significant associations between CHL disease relapse (DR) or overall survival (OS) and 4 DNA repair genes were observed, with the exception of xeroderma pigmentosum, complementation group G (XPG) repair gene SNP (rs17655), which revealed a statistically significant association with CHL patient survival (P=0.036). Accordingly, these data suggest that the XPG gene may be a useful predictive molecular genetic biomarker for CHL clinical outcome. The present study also provided valuable insights on the contribution of DNA repair genes in Saudi patients with CHL. To the best of our knowledge, we defined for the first time, a specific genetic pattern associated with CHL outcome was defined in the present study in Saudi patients.

CCR5 antagonism by maraviroc inhibits Hodgkin lymphoma microenvironment interactions and xenograft growth

Classic Hodgkin lymphoma tumor cells express a functional CCR5 receptor, and tumor tissues express high CCL5 levels, suggesting that CCL5-CCR5 signaling is involved in tumor-microenvironment formation and tumor growth. Using the CCR5 antagonist, maraviroc, and a neutralizing anti-CCL5 antibody, we found that CCL5 secreted by classic Hodgkin lymphoma cells recruited mesenchymal stromal cells and monocytes. The “education” of mesenchymal stromal cells by tumor cell-conditioned medium enhanced mesenchymal stromal cells’ proliferation and CCL5 secretion. In turn, educated mesenchymal stromal cell-conditioned medium increased the clonogenic growth of tumor cells and monocyte migration, but these effects were reduced by maraviroc. Monocyte education by tumor cell-conditioned medium induced their growth and reprogrammed them towards immunosuppressive tumor-associated macrophages that expressed IDO and PD-L1 and secreted IL-10, CCL17 and TGF-β. Educated monocyte-conditioned medium slowed the growth of phytohemagglutinin-activated lymphocytes. Maraviroc decreased tumor cell growth and synergized with doxorubicin and brentuximab vedotin. A three-dimensional heterospheroid assay showed that maraviroc counteracted both the formation and viability of heterospheroids generated by co-cultivation of tumor cells with mesenchymal stromal cells and monocytes. In mice bearing tumor cell xenografts, maraviroc reduced tumor growth by more than 50% and inhibited monocyte accumulation, without weight loss. Finally, in classic Hodgkin lymphoma human tumor tissues, CCL5 and CD68 expression correlated positively, and patients with high CCL5 levels had poor prognosis. In conclusion, since the present challenges are to find molecules counteracting the formation of the immunosuppressive tumor microenvironment or new, less toxic drug combinations, the repurposed drug maraviroc may represent a new opportunity for classic Hodgkin lym phoma treatment.

Biology of classical Hodgkin lymphoma: implications for prognosis and novel therapies

Hodgkin lymphoma is considered a prime example of treatment success, with cure rates exceeding 80% using modern combined modality therapies. However, especially in adolescents and young adults, treatment-related toxicity and long-term morbidity still represent persistent challenges. Moreover, outcomes in patients with relapsed or refractory disease remain unfavorable in the era of high-dose chemotherapy and stem-cell transplantation. Hence, there is a high demand for novel and innovative alternative treatment approaches. In recent years, many new therapeutic agents have emerged from preclinical and clinical studies that target molecular hallmarks of Hodgkin lymphoma, including the aberrant phenotype of the tumor cells, deregulated oncogenic pathways, and immune escape. The antibody-drug conjugate brentuximab vedotin and immune checkpoint inhibitors have already shown great success in patients with relapsed/refractory disease, leading to US Food and Drug Administration approval and new trials testing these agents in various clinical settings. The expanding knowledge and understanding of Hodgkin lymphoma biology and disease progression, as well as the development of robust tools for biomarker-driven risk stratification and therapeutic decision making, continue to be fundamentally important for the success of these and other novel agents. We anticipate that the availability and clinical implementation of novel molecular assays will be instrumental in an era of rapid shifts in the treatment landscape of this disease. Here, we review the current knowledge of Hodgkin lymphoma pathobiology, highlighting the related development of novel treatment strategies and prognostic models that hold the promise to continually challenge and change the current standard of care in classical Hodgkin lymphoma.

Interim PET Response-adapted Strategy in Untreated Advanced Stage Hodgkin Lymphoma: Results of GOELAMS LH 2007 Phase 2 Multicentric Trial

BACKGROUND

Patients with advanced stage Hodgkin lymphoma still present unsatisfactory outcomes.

PATIENTS AND METHODS

The Groupe d'étude des Leucémies Aigues et des Maladies du Sang (GOELAMS) group conducted a prospective multicentric trial (NCT00920153) for advanced stage Hodgkin lymphoma to evaluate a positron emission tomography (PET)-adapted strategy. Patients received an intensive regimen (VABEM [vindesine, doxorubicin, carmustine, etoposide, and methylprednisolone]) in front-line and interim ^18FFDG-PET evaluation after 2 courses (PET-2). Patients with negative PET-2 findings received 1 additional course. Patients with positive PET-2 findings underwent early salvage therapy followed by high-dose therapy/autologous stem cell transplantation.

RESULTS

Fifty-one patients were included. The final complete remission rate was 88%. With a median follow up of 5.3 years, 5-year event-free survival and overall survival rates were 75.3% and 85.3%, respectively, for the whole cohort. Patients who were PET-2-negative had 5-year event-free survival and overall survival rates of, respectively, 77.8% and 88.2% versus 85.1% and 91.7% for patients who were PET-2-positive.

CONCLUSION

A PET-guided strategy with early salvage therapy and high-dose therapy/autologous stem cell transplantation for patients with interim PET-2-positive findings is safe and feasible and provide similar outcome as patients with a negative PET-2.

Hodgkin's lymphoma and its association with EBV and HIV infection

Hodgkin's lymphoma (HL) constitutes a clonal expansion of what appears to be malignant B cells. Viruses are involved in its pathogenesis, such as the Epstein-Barr virus (EBV) and human immunodeficiency virus (HIV). Since these viral infections have been shown to play key roles in the pathogenesis of HL, countries with a prevalence of HIV and EBV represent interesting population targets to study the pathogenesis of HL, linking the evolution of the disease with viral infections. Usually, patients present with late stage disease often involving the bone marrow at the time of diagnosis. The present paper discusses the role of viral infection in African countries, as HL is considered to be a malignant disease characterized by an inflammatory reaction to an aberrant B cell clone that is well known as the Reed-Sternberg cell (HRS).

Challenges and perspectives in the immunotherapy of Hodgkin lymphoma

Hodgkin lymphoma (HL) was one of the first few cancers to be cured first with radiotherapy alone and then with a combination of chemotherapy and radiotherapy. Around 80% of the patients with HL will be cured by first-line therapy. However, the ionising radiation not only produces cytotoxicity but also induces alterations in the microenvironment, and patients often struggle with the long-term consequences of these treatments, such as cardiovascular disorders, lung diseases and secondary malignancies. Hence, it is essential to improve treatments while avoiding delayed side-effects. Immunotherapy is a promising new treatment option for Hodgkin lymphoma, and anti- programmed death-1 (PD1) agents have produced striking results in patients with relapsed or refractory disease. The microenvironment of Hodgkin lymphoma appears to be unique in the field of human disease: the malignant Reed-Sternberg cells only constitute 1% of the cells in the lymphoma, but they are surrounded by an extensive immune infiltrate. Reed-Sternberg cells exhibit 9p24.1/PD-L1/PD-L2 copy number alterations and genetic rearrangements associated with programmed cell death ligand 1/ ligand 2 (PD-L1/2) overexpression, together with major histocompatibility complex-I (MHC-I) and major histocompatibility complex-II (MHC-II) downregulation (which may facilitate the tumour's immune evasion). Although HL may be a situation in which defective immune surveillance is restored by anti-PD1 therapy, it challenges our current explanation of how anti-PD1 agents work because MHC-I expression is required for CD8-T-cell-mediated tumour antigen recognition. Here, we review recent attempts to understand the defects in immune recognition in HL and to design an optimal evidence-based treatment for combination with anti-PD1.

High proportions of PD-1+ and PD-L1+ leukocytes in classical Hodgkin lymphoma microenvironment are associated with inferior outcome

Immune checkpoint inhibition targeting the programmed death receptor (PD)-1 pathway is a novel treatment approach in relapsed and refractory classical Hodgkin lymphoma (cHL). Identifying patients with a high risk of treatment failure could support the use of PD-1 inhibitors as front-line treatment. Our aim was to investigate the prognostic impact of PD-1, programmed death-ligand 1 (PD-L1), and PD-L2 in the tumor microenvironment in diagnostic biopsies of patients with cHL. Patients from Denmark and Sweden, diagnosed between 1990 and 2007 and ages 15 to 86 years, were included. Tissue microarray samples were available from 387 patients. Immunohistochemistry was used to detect PD-1, PD-L1, and PD-L2, and the proportions of positive cells were calculated. Event-free survival (EFS; time to treatment failure) and overall survival (OS) were analyzed using Cox proportional hazards regression. High proportions of both PD-1⁺ (hazard ratio [HR], 1.77; 95% confidence interval [CI], 1.10-2.86) and PD-L1⁺ (HR = 1.89; 95% CI, 1.08-3.30) leukocytes in the microenvironment were associated with inferior EFS in a multivariate analysis (adjusted for white blood cell count >15 × 10⁹/L, hemoglobin <105 g/L, albumin <40 g/L, B symptoms, extranodal involvement, stage, bulky tumor, nodular sclerosis subtype, Epstein-Barr virus status, lymphocyte count <0.6 × 10⁹/L, sex, and country). A high proportion of PD-L1⁺ leukocytes was also associated with inferior OS in a multivariate analysis (HR, 3.46; 95% CI, 1.15-10.37). This is the first study to show a correlation after multivariate analysis between inferior outcome in cHL and a high proportion of both PD-1⁺ and PD-L1⁺ leukocytes in the tumor microenvironment.

New Mechanisms of Tumor-Associated Macrophages on Promoting Tumor Progression: Recent Research Advances and Potential Targets for Tumor Immunotherapy

The majority of basic and clinical studies have shown a protumor function of tumor-associated macrophages (TAMs), which represent a large proportion of matrix cells. TAMs promote tumorigenesis, and their number is related to the malignancy degree and poor prognosis of many kinds of tumors. Macrophage plasticity makes it possible to change the tumor microenvironment and remodel antitumor immunity during cancer immunotherapy. Increasing numbers of studies have revealed the effects of TAMs on the tumor microenvironment, for example, via promotion of tumor growth and tumorigenesis and through an increase in the number of cancer stem cells or via facilitation of angiogenesis, lymphangiogenesis, and metastasis. Investigators also proposed tumor-immunological treatments targeting TAMs by inhibiting TAM recruitment and differentiation, by regulating TAM polarization, and by blocking factors and pathways associated with the protumor function of TAMs. This comprehensive review presents recent research on TAMs in relation to prediction of poor outcomes, remodeling of the tumor immune microenvironment, and immunological targeted therapies.

Emerging therapies provide new opportunities to reshape the multifaceted interactions between the immune system and lymphoma cells

The acquisition of a complete neoplastic phenotype requires cancer cells to develop escape mechanisms from the host immune system. This phenomenon, commonly referred to as 'immune evasion,' represents a hallmark of cancers and results from a Darwinian selection of the fittest tumor clones. First reported in solid tumors, cancer immunoescape characterizes several hematological malignancies. The biological bases of cancer immunoescape have recently been disclosed and include: (i) impaired human leukocyte antigen-mediated cancer cell recognition (B2M, CD58, CTIIA, CD80/CD86, CD28 and CTLA-4 mutations); (ii) deranged apoptotic mechanisms (reduced pro-apoptotic signals and/or increased expression of anti-apoptotic molecules); and (iii) changes in the tumor microenvironment involving regulatory T cells and tumor-associated macrophages. These immune-escape mechanisms characterize both Hodgkin and non-Hodgkin (B and T cell) lymphomas and represent a promising target for new anti-tumor therapies. In the present review, the principles of cancer immunoescape and their role in human lymphomagenesis are illustrated. Current therapies targeting these pathways and possible applications for lymphoma treatment are also addressed.

Characterization of the tumor microenvironment in primary cutaneous CD30-positive lymphoproliferative disorders: a predominance of CD163-positive M2 macrophages

BACKGROUND

The tumor microenvironment is essential for tumor survival, growth and progression. There are only a few studies on the tumor microenvironment in cutaneous CD30-positive lymphoproliferative disorders.

METHODS

We assessed the composition of the tumor microenvironment using immunohistochemistry studies in skin biopsies from cases diagnosed with lymphomatoid papulosis (LyP: 18 specimens), primary cutaneous anaplastic large-cell lymphoma (PC-ALCL: 8 specimens), and reactive diseases harboring CD30-positive cells (18 specimens).

RESULTS

The predominant cells present in LyP and PC-ALCL were CD163+ M2 macrophages (44.7%, 35%), followed by CD8+ tumor infiltrating lymphocytes (11%, 15%), FOXP3+ T-regulatory cells (9%, 4.5%) and programmed cell death 1(PD-1) + lymphocytes (2.2%, 6.8%). In contrast, CD30-positive reactive inflammatory and infectious disorders were characterized by higher numbers of CD123+ plasmacytoid dendritic cells (6.3%) when compared to LyP (1%), and PC-ALCL (1.1%).

CONCLUSIONS

Key differences exist between the microenvironment of CD30-positive lymphoproliferative disorders and reactive conditions harboring CD30-positive lymphocytes. The high number of tumor associated macrophages, and the close vicinity of these immune cells to the CD30-positive tumor cells might suggest that tumor associated macrophages have direct influence on tumorigenesis in LyP and ALCL. Therefore, modulation of M2 macrophages may represent a new therapeutic strategy in cutaneous CD30-positive lymphoproliferative disorders.

HLA-G expression and role in advanced-stage classical Hodgkin lymphoma

Non-classical human leucocyte antigen (HLA)-G class I molecules have an important role in tumor immune escape mechanisms. We investigated HLA-G expression in lymphonode biopsies taken from 8 controls and 20 patients with advanced-stage classical Hodgkin lymphoma (cHL), in relationship to clinical outcomes and the HLA-G 14-basepair (14-bp) deletion-insertion (del-ins) polymorphism. Lymphnode tissue sections were stained using a specific murine monoclonal HLA-G antibody. HLA-G protein expression was higher in cHL patients than controls. In the group of PET-2 positive (positron emission tomography carried out after 2 cycles of standard chemotherapy) patients with a 2-year progression-free survival rate (PFS) of 40%, we observed high HLA-G protein expression within the tumor microenvironment with low expression on Hodgkin and Reed-Sternberg (HRS) cells. Conversely, PET-2 negative patients with a PFS of 86% had higher HLA-G protein expression levels on HRS cells compared to the microenvironment. Lower expression on HRS cells was significantly associated with the HLA-G 14-bp ins/ins genotype.

These preliminary data suggest that the immunohistochemical pattern of HLA-G protein expression may represent a useful tool for a tailored therapy in patients with cHL, based on the modulation of HLA-G expression in relation to achievement of negative PET-2.

The favorable role of homozygosity for killer immunoglobulin-like receptor (KIR) A haplotype in patients with advanced-stage classic Hodgkin lymphoma

BACKGROUND

Interim positron emission tomography after 2 cycles of ABVD (iPET-2) is a good predictor of outcome in advanced-stage classic Hodgkin lymphoma. So far, there are no other prognostic biomarkers capable of identifying chemotherapy refractory patients with comparable accuracy. Despite the considerable amount of evidence suggesting that antitumor immune surveillance is downregulated in classic Hodgkin lymphoma (cHL), few data exist on the impairment of natural killer cell function and the role of their killer immunoglobulin-like receptors (KIRs).

METHODS

We investigated KIR gene frequencies, KIR haplotypes, and KIR-ligand combinations in a cohort of 135 patients with advanced-stage classic Hodgkin lymphoma and 221 healthy controls. We furthermore evaluated the correlation of KIR genes and KIR haplotypes with the achievement of negative iPET-2.

RESULTS

In the cohort of patients, the 5-year overall survival and progression-free survival were 93.6 and 79%, respectively. Homozygosity for KIR A haplotype and the HLA-C1 KIR ligand (KIR-AA/C1C1) was significantly higher in healthy controls (15.7 vs. 4.8%, p = 0.001). The KIR-AA genotype resulted to have a significant predictive power for achieving iPET-2 negativity (p = 0.039).

CONCLUSIONS

Homozygosity for KIR A haplotype offers protection against classic Hodgkin lymphoma. The association found for the KIR-AA genotype and achievement of negative iPET-2 suggests that KIR-AA could be used in clinical practice to enhance the chemosensitivity predictive power of iPET-2. Our results point to the possibility of adapting treatment strategies based on the combination of KIR biomarkers and PET scan.

Stromal immune infiltration in HIV-related diffuse large B-cell lymphoma is associated with HIV disease history and patient survival

OBJECTIVE

Understanding tumor microenvironment and its impact on prognosis of HIV-related lymphomas may provide insight into novel therapeutic strategies.

DESIGN

We characterized the relationship between infiltrating immune cells with tumor characteristics, HIV disease history and survival in 80 patients with HIV-related diffuse large B-cell lymphoma (DLBCL) diagnosed in the era of combined antiretroviral therapy (1996-2007) at Kaiser Permanente California. Eighty patients with HIV-unrelated DLBCL were included for comparison.

METHODS

Data on patients' clinical history were obtained from Kaiser Permanente's electronic health records. The density of stromal CD4, CD8 and FOXP3 T cells and CD68 macrophages, as well as tumor molecular characteristics were examined using immunohistochemistry. The associations between stromal immune infiltration and patient's clinical history or tumor characteristics were examined using Kruskal-Wallis tests or Pearson's correlation coefficient. The effect of stromal immune infiltration on 2-year mortality was evaluated in multivariable logistic regression.

RESULTS

Compared with HIV-unrelated DLBCL, patients with HIV-related DLBCL had significantly reduced stromal CD4 and FOXP3 T cells, but increased density of macrophages. Increased density of stromal macrophages was correlated with lower circulating CD4 cell count at DLBCL diagnosis. Tumor molecular characteristics, including BCL6, p53 and cMYC expression, but not Epstein-Barr virus infection status, were significantly correlated with stromal immune infiltration, particularly FOXP3 T cells. A higher density of infiltrating CD8 T cell was significantly associated with reduced mortality in patients with HIV-related DLBCL (odds ratio = 0.30 [0.09-0.97] for ≥25 vs. <10%).

CONCLUSION

These data provide evidence for the prognostic significance of cytotoxic T cells in determining outcomes of HIV-related lymphoma.

Absolute Monocyte Count and Lymphocyte-Monocyte Ratio Predict Outcome in Nodular Sclerosis Hodgkin Lymphoma: Evaluation Based on Data From 1450 Patients

OBJECTIVE

To verify whether absolute monocyte count (AMC) and lymphocyte- monocyte ratio (LMR) at diagnosis are valid prognostic parameters in classical Hodgkin lymphoma (cHL).

PATIENTS AND METHODS

Data were collected from 1450 patients with cHL treated in Israel and Italy from January 1, 1988, through December 31, 2007.

RESULTS

The median age of the patients was 33 years (range, 17-72 years), and 70% (1017) of the patients had nodular sclerosis (NS); the median follow-up duration was 87 months. The best cutoff value for AMC was 750 cells/mm(3), and the best ratio for LMR was 2.1. The adverse prognostic impact of an AMC of more than 750 cells/mm(3) was confirmed for the entire cohort, and its clinical significance was particularly evident in patients with NS histology. The progression-free survival (PFS) at 10 years for an AMC of more than 750 cells/mm(3) was 65% (56%-72%), and the PFS at 10 years for an AMC of 750 cells/mm(3) or less was 81% (76%-84%; P<.001). The overall survival (OS) at 10 years for an AMC of more than 750 cells/mm(3) was 78% (70%-85%), and the OS at 10 years for an AMC of 750 cells/mm(3) or less was 88% (84%-90%; P=.01). In multivariate analysis, both AMC and LMR maintained prognostic significance for PFS (hazard ratio [HR], 1.54, P=.006, and HR, 1.50, P=.006) after adjusting for the international prognostic score, whereas the impact on OS was confirmed (HR, 1.56; P=.04) only in patients with NS and an AMC of more than 750 cells/mm(3).

CONCLUSION

This study confirms that AMC has prognostic value in cHL that is particularly significant in patients with NS subtype histology. This finding links the known impact of macrophages and monocytes in Hodgkin lymphoma with routine clinical practice.