Gene expression profiling defines molecular subtypes of classical Hodgkin's disease

Adult Hodgkin lymphoma incidence trends in the United States from 2000 to 2020

Hodgkin lymphoma (HL) is a rare malignancy affecting the lymphatic system. Our study examined the incidence rates of adult HL based on sex, race/ethnicity, age, and histological subgroups in the United States (US) from 2000 to 2020. Data for this study were extracted from the Surveillance, Epidemiology, and End Results 22 database. HL patients were identified utilizing the International Classification of Diseases for Oncology version 3 and categorized as classical HL, lymphocyte-rich/mixed cell/lymphocyte depleted, nodular sclerosis, classical HL, not otherwise specified, and nodular lymphocyte-predominant HL. The study reported average annual percent change (AAPC). All estimates were presented as counts and age-standardized incidence rates (ASIRs) per 100,000 individuals. Between 2000 and 2019, a total of 70,924 cases of HL were reported in the US. Classical HL was the predominant subtype (94.27%), and most incident cases were among non-Hispanic Whites (66.92%) and those aged 20-29 years (24.86%). The ASIR per 100,000 population was 3.83 for men and 2.92 for women. Both sexes showed declines in the AAPCs between 2000 and 2019 (- 0.64% [- 0.99, - 0.28] and - 0.40% [- 0.77, - 0.03] for men and women, respectively). There was a significant decrease in ASIRs after COVID-19 among both sexes (percent change: - 7.49% [- 11.58, - 3.40]). Throughout all age groups, men had a higher incidence rate compared to women, except for those aged 20-29 years. Although the overall HL incidence rate was lowered in the study period from 2000 to 2019, a dramatic decrease in ASIRs of HL patients following COVID-19 pandemic was observed.

Molecular biomarkers in classic Hodgkin lymphoma

Classic Hodgkin lymphoma is a unique B-cell derived malignancy featuring rare malignant Hodgkin and Reed Sternberg (HRS) cells that are embedded in a quantitively dominant tumor microenvironment (TME). Treatment of classic Hodgkin lymphoma has significantly evolved in the past decade with improving treatment outcomes for newly diagnosed patients and the minority of patients suffering from disease progression. However, the burden of toxicity and treatment-related long-term sequelae remains high in a typically young patient population. This highlights the need for better molecular biomarkers aiding in risk-adapted treatment strategies and predicting response to an increasing number of available treatments that now prominently involve multiple immunotherapy options. Here, we review modern molecular biomarker approaches that reflect both the biology of the malignant HRS cells and cellular components in the TME, while holding the promise to improve diagnostic frameworks for clinical decision-making and be feasible in clinical trials and routine practice. In particular, technical advances in sequencing and analytic pipelines using liquid biopsies, as well as deep phenotypic characterization of tissue architecture at single-cell resolution, have emerged as the new frontier of biomarker development awaiting further validation and implementation in routine diagnostic procedures.

Immune and stromal transcriptional patterns that influence the outcome of classic Hodgkin lymphoma

Classic Hodgkin lymphoma (cHL) is characterized by a rich immune microenvironment as the main tumor component. It involves a broad range of cell populations, which are largely unexplored, even though they are known to be essential for growth and survival of Hodgkin and Reed-Sternberg cells. We profiled the gene expression of 25 FFPE cHL samples using NanoString technology and resolved their microenvironment compositions using cell-deconvolution tools, thereby generating patient-specific signatures. The results confirm individual immune fingerprints and recognize multiple clusters enriched in refractory patients, highlighting the relevance of: (1) the composition of immune cells and their functional status, including myeloid cell populations (M1-like, M2-like, plasmacytoid dendritic cells, myeloid-derived suppressor cells, etc.), CD4-positive T cells (exhausted, regulatory, Th17, etc.), cytotoxic CD8 T and natural killer cells; (2) the balance between inflammatory signatures (such as IL6, TNF, IFN-γ/TGF-β) and MHC-I/MHC-II molecules; and (3) several cells, pathways and genes related to the stroma and extracellular matrix remodeling. A validation model combining relevant immune and stromal signatures identifies patients with unfavorable outcomes, producing the same results in an independent cHL series. Our results reveal the heterogeneity of immune responses among patients, confirm previous findings, and identify new functional phenotypes of prognostic and predictive utility.

Efficacy and Nuances of Precision Molecular Engineering for Hodgkin's Disease to a Gene Therapeutic Approach

Gene therapy is a particularly useful treatment for nervous system genetic diseases, including those induced especially by infectious organisms and antigens, and is being utilized to treat Hodgkin's disease (HD). Due to the possible clonal relationship between both disorders, immunotherapy directed against CD20 positive cells may be a more effective treatment in patients with persistent HD and NHL. HL growth can be inhibited both in vitro and in vivo by AdsIL-13Ralpha2. High-dose treatment combined with stem cell transplantation has been effective in treating HIV-negative lymphoma that has progressed to high-risk or relapsed disease. For therapy, LMP2-specific CTL will be used. Furthermore, it is possible to view the cytotoxicity of genetically modified adenoviruses that express proteins such as p27Kip1, p21Waf1, and p16INK4A as a foundational element for (2,5)-derived ALCL genetic treatment for Hodgkin's disease.

On the challenges of predicting treatment response in Hodgkin's Lymphoma using transcriptomic data

BACKGROUND

Despite the advancements in multiagent chemotherapy in the past years, up to 10% of Hodgkin's Lymphoma (HL) cases are refractory to treatment and, after remission, patients experience an elevated risk of death from all causes. These complications are dependent on the treatment and therefore an increase in the prognostic accuracy of HL can help improve these outcomes and control treatment-related toxicity. Due to the low incidence of this cancer, there is a lack of works comprehensively assessing the predictability of treatment response, especially by resorting to machine learning (ML) advances and high-throughput technologies.

METHODS

We present a methodology for predicting treatment response after two courses of Adriamycin, Bleomycin, Vinblastine and Dacarbazine (ABVD) chemotherapy, through the analysis of gene expression profiles using state-of-the-art ML algorithms. We work with expression levels of tumor samples of Classical Hodgkin's Lymphoma patients, obtained through the NanoString's nCounter platform. The presented approach combines dimensionality reduction procedures and hyperparameter optimization of various elected classifiers to retrieve reference predictability levels of refractory response to ABVD treatment using the regulatory profile of diagnostic tumor samples. In addition, we propose a data transformation procedure to map the original data space into a more discriminative one using biclustering, where features correspond to discriminative putative regulatory modules.

RESULTS

Through an ensemble of feature selection procedures, we identify a set of 14 genes highly representative of the result of an fuorodeoxyglucose Positron Emission Tomography (FDG-PET) after two courses of ABVD chemotherapy. The proposed methodology further presents an increased performance against reference levels, with the proposed space transformation yielding improvements in the majority of the tested predictive models (e.g. Decision Trees show an improvement of 20pp in both precision and recall).

CONCLUSIONS

Taken together, the results reveal improvements for predicting treatment response in HL disease by resorting to sophisticated statistical and ML principles. This work further consolidates the current hypothesis on the structural difficulty of this prognostic task, showing that there is still a considerable gap to be bridged for these technologies to reach the necessary maturity for clinical practice.

Distinctive patterns of marrow involvement by classic Hodgkin lymphoma are clues for diagnosis and subtyping

Classic Hodgkin lymphoma (CHL) is a lymphoid neoplasm deriving from B cells in a rich inflammatory background. There are four histological subtypes with different epidemiological features. Bone marrow involvement by CHL is infrequent, and subtyping CHL from the bone marrow is not suggested as there might be discordant histopathology between the primary tumors and bone marrow specimens. In this study, we aimed to identify the histopathological features of bone marrow involved by CHL and tried to correlate these features with their subtypes. Among the 23 recruited cases, the frequencies of mixed cellularity (MC; 48%, 11/23) and nodular sclerosis (NS; 44%, 10/23) were similar. There were two patterns of marrow involvement: pattern A (fibrous), space-occupying lesions with alternating hypo- and hypercellular areas against a fibrotic background with dilated sinusoids and pattern B (histiocyte-rich), ill-defined granuloma-like lesions in which histiocytes merged with normal hematopoietic and inflammatory cells. Pattern A was more frequent in patients with CHL-NS than CHL-MC (100% vs. 18.2%; p < 0.001). Diagnostic Hodgkin cells and Reed-Sternberg (HRS) cells were identified in all cases, while HRS variant lacunar cells were occasionally discovered, particularly in the CHL-NS subtype (NS 100% vs. MC 9%; p < 0.001). The frequency of EBV association was higher in MC (64%) than that in NS (36%) subtype, but not statistically significant. Of the two patterns of marrow involvement, pattern A was more commonly associated with the NS subtype and less frequently associated with EBV. Recognizing the patterns of marrow involvement is important for diagnosis and may contribute to the subtyping of CHL.

Lysyl-Oxidase Dependent Extracellular Matrix Stiffness in Hodgkin Lymphomas: Mechanical and Topographical Evidence

Simple Summary

Alterations of the composition and architecture of the extracellular matrix (ECM), leading to increased stiffness, is known to condition development, invasiveness and severity of neoplasms. In this study, we report increased lymph node (LN) stiffness in human lymphomas, measured by LN elastometry or by computerized imaging of bioptic specimens. Stiffness matched to lymphoma histotype and grading. The enzyme lysyl oxidase (LOX) is involved in the rise of collagen cross-linking in Hodgkin lymphomas, while altered architecture, shown by scanning electron microscopy and polarized light microscopy is involved in advanced follicular lymphomas. Based on these data, digital pathology may help in the staging of lymphomas, and lysyl oxidase may represent a target for therapy in Hodgkin lymphomas.

Abstract

Purpose: The biochemical composition and architecture of the extracellular matrix (ECM) is known to condition development and invasiveness of neoplasms. To clarify this point, we analyzed ECM stiffness, collagen cross-linking and anisotropy in lymph nodes (LN) of Hodgkin lymphomas (HL), follicular lymphomas (FL) and diffuse large B-cell lymphomas (DLBCL), compared with non-neoplastic LN (LDN). Methods and Results: We found increased elastic (Young’s) modulus in HL and advanced FL (grade 3A) over LDN, FL grade 1–2 and DLBCL. Digital imaging evidenced larger stromal areas in HL, where increased collagen cross-linking was found; in turn, architectural modifications were documented in FL3A by scanning electron microscopy and enhanced anisotropy by polarized light microscopy. Interestingly, HL expressed high levels of lysyl oxidase (LOX), an enzyme responsible for collagen cross-linking. Using gelatin scaffolds fabricated with a low elastic modulus, comparable to that of non-neoplastic tissues, we demonstrated that HL LN-derived mesenchymal stromal cells and HL cells increased the Young’s modulus of the extracellular microenvironment through the expression of LOX. Indeed, LOX inhibition by β-aminopropionitrile prevented the gelatin stiffness increase. Conclusions: These data indicate that different mechanical, topographical and/or architectural modifications of ECM are detectable in human lymphomas and are related to their histotype and grading.

Hodgkin Lymphoma: A Special Microenvironment

Classical Hodgkin's lymphoma (cHL) is one of the most particular lymphomas for the few tumor cells surrounded by an inflammatory microenvironment. Reed-Sternberg (RS) and Hodgkin (H) cells reprogram and evade antitumor mechanisms of the normal cells present in the microenvironment. The cells of microenvironment are essential for growth and survival of the RS/H cells and are recruited through the effect of cytokines/chemokines. We summarize recent advances in gene expression profiling (GEP) analysis applied to study microenvironment component in cHL. We also describe the main therapies that target not only the neoplastic cells but also the cellular components of the background.

The landscape of copy number variations in classical Hodgkin lymphoma: a joint KU Leuven and LYSA study on cell-free DNA

The low abundance of Hodgkin/Reed-Sternberg (HRS) cells in lymph node biopsies in classical Hodgkin lymphoma (cHL) complicates the analysis of somatic genetic alterations in HRS cells. As circulating cell-free DNA (cfDNA) contains circulating tumor DNA (ctDNA) from HRS cells, we prospectively collected cfDNA from 177 patients with newly diagnosed, mostly early-stage cHL in a monocentric study at Leuven, Belgium (n = 59) and the multicentric BREACH study by Lymphoma Study Association (n = 118). To catalog the patterns and frequencies of genomic copy number aberrations (CNAs), cfDNA was sequenced at low coverage (0.26×), and data were analyzed with ichorCNA to yield read depth-based copy number profiles and estimated clonal fractions in cfDNA. At diagnosis, the cfDNA concentration, estimated clonal fraction, and ctDNA concentration were significantly higher in cHL cases than controls. More than 90% of patients exhibited CNAs in cfDNA. The most frequent gains encompassed 2p16 (69%), 5p14 (50%), 12q13 (50%), 9p24 (50%), 5q (44%), 17q (43%), 2q (41%). Losses mostly affected 13q (57%), 6q25-q27 (55%), 4q35 (50%), 11q23 (44%), 8p21 (43%). In addition, we identified loss of 3p13-p26 and of 12q21-q24 and gain of 15q21-q26 as novel recurrent CNAs in cHL. At diagnosis, ctDNA concentration was associated with advanced disease, male sex, extensive nodal disease, elevated erythrocyte sedimentation rate, metabolic tumor volume, and HRS cell burden. CNAs and ctDNA rapidly diminished upon treatment initiation, and persistence of CNAs was associated with increased probability of relapse. This study endorses the development of ctDNA as gateway to the HRS genome and substrate for early disease response evaluation.

Cell-Free DNA for the Management of Classical Hodgkin Lymphoma

Cell-free DNA (cfDNA) testing, is an emerging “liquid biopsy” tool for noninvasive lymphoma detection, and an increased amount of data are now available to use this technique with accuracy, especially in classical Hodgkin lymphoma (cHL). The advantages of cfDNA include simplicity of repeated blood sample acquisition over time; dynamic, noninvasive, and quantitative analysis; fast turnover time; reasonable cost; and established consistency with results from tumor genomic DNA. cfDNA analysis offers an easy method for genotyping the overall molecular landscape of pediatric and adult cHL and may help in cases of diagnostic difficulties between cHL and other lymphomas. cfDNA levels are correlated with clinical, prognostic, and metabolic features, and may serve as a therapeutic response evaluation tool and as a minimal residual disease (MRD) biomarker in complement to positron emission tomography (PET). Indeed, cfDNA real-time monitoring by fast high-throughput techniques enables the prompt detection of refractory disease or may help to address PET residual hypermetabolic situations during or at the end of treatment. The major recent works presented and described here demonstrated the clinically meaningful applicability of cfDNA testing in diagnostic and theranostic settings, but also in disease risk assessment, therapeutic molecular response, and monitoring of cHL treatments.

Hodgkin lymphoma

Hodgkin lymphoma (HL) is a B cell lymphoma characterized by few malignant cells and numerous immune effector cells in the tumour microenvironment. The incidence of HL is highest in adolescents and young adults, although HL can affect elderly individuals. Diagnosis is based on histological and immunohistochemical analyses of tissue from a lymph node biopsy; the tissue morphology and antigen expression profile enable classification into one of the four types of classic HL (nodular sclerosis, mixed cellularity, lymphocyte-depleted or lymphocyte-rich HL), which account for the majority of cases, or nodular lymphocyte-predominant HL. Although uncommon, HL remains a crucial test case for progress in cancer treatment. HL was among the first systemic neoplasms shown to be curable with radiation therapy and multiagent chemotherapy. The goal of multimodality therapy is to minimize lifelong residual treatment-associated toxicity while maintaining high levels of effectiveness. Recurrent or refractory disease can be effectively treated or cured with high-dose chemotherapy followed by autologous haematopoietic stem cell transplantation, and prospective trials have demonstrated the potency of immunotherapeutic approaches with antibody-drug conjugates and immune checkpoint inhibitors. This Primer explores the wealth of information that has been assembled to understand HL; these updated observations verify that HL investigation and treatment remain at the leading edge of oncological research.

Novel Biomarker Approaches in Classic Hodgkin Lymphoma

Classic Hodgkin lymphoma (cHL) is one of the most common lymphomas in the Western world. Advances in the management of cHL have led to high cure rates exceeding 80%. Nevertheless, relapse or refractory disease in a subset of patients and treatment-related toxicity still represents unsolved clinical problems. The introduction of targeted treatments such as PD-1 blockade and the CD30 antibody drug conjugate, brentuximab vedotin, has broadened treatment options in cHL, emphasizing the critical need to identify biomarkers with the goal to provide rationales for treatment selection, increase effective drug utilization, and minimize toxicity. The unique biology of cHL featuring low abundant tumor cells and numerous nonmalignant immune cells in the tumor microenvironment can provide various types of promising biomarkers related to the tumor cells directly, tumor microenvironment cross-talk, and host immune response. Here, we comprehensively review novel biomarkers including circulating tumor DNA and gene expression-based prognostic models that might guide the ideal management of cHL in the future.

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.

Overcoming the Immunosuppressive Tumor Microenvironment of Hodgkin Lymphoma Using Chimeric Antigen Receptor T Cells

Patients with otherwise treatment-resistant Hodgkin lymphoma could benefit from chimeric antigen receptor T-cell (CART) therapy. However, Hodgkin lymphoma lacks CD19 and contains a highly immunosuppressive tumor microenvironment (TME). We hypothesized that in Hodgkin lymphoma, CART should target both malignant cells and the TME. We demonstrated CD123 on both Hodgkin lymphoma cells and TME, including tumor-associated macrophages (TAM). In vitro, Hodgkin lymphoma cells convert macrophages toward immunosuppressive TAMs that inhibit T-cell proliferation. In contrast, anti-CD123 CART recognized and killed TAMs, thus overcoming immunosuppression. Finally, we showed in immunodeficient mouse models that CART123 eradicated Hodgkin lymphoma and established long-term immune memory. A novel platform that targets malignant cells and the microenvironment may be needed to successfully treat malignancies with an immunosuppressive milieu.Significance: Anti-CD123 chimeric antigen receptor T cells target both the malignant cells and TAMs in Hodgkin lymphoma, thereby eliminating an important immunosuppressive component of the tumor microenvironment. Cancer Discov; 7(10); 1154-67. ©2017 AACR.This article is highlighted in the In This Issue feature, p. 1047.

Transcriptome Analysis of Canine Cutaneous Melanoma and Melanocytoma Reveals a Modulation of Genes Regulating Extracellular Matrix Metabolism and Cell Cycle

Interactions between tumor cells and tumor microenvironment are considered critical in carcinogenesis, tumor invasion and metastasis. To examine transcriptome changes and to explore the relationship with tumor microenvironment in canine cutaneous melanocytoma and melanoma, we extracted RNA from formalin-fixed, paraffin-embedded (FFPE) specimens and analyzed them by means of RNA-seq for transcriptional analysis. Melanocytoma and melanoma samples were compared to detect differential gene expressions and significant enriched pathways were explored to reveal functional relations between differentially expressed genes. The study demonstrated a differential expression of 60 genes in melanomas compared to melanocytomas. The differentially expressed genes cluster in the extracellular matrix-receptor interaction, protein digestion and absorption, focal adhesion and PI3K-Akt (phosphoinositide 3-kinase/protein kinase B) signaling pathways. Genes encoding for several collagen proteins were more commonly differentially expressed. Results of the RNA-seq were validated by qRT-PCR and protein expression of some target molecules was investigated by means of immunohistochemistry. We hypothesize that the developing melanoma actively promotes collagen metabolism and extracellular matrix remodeling as well as enhancing cell proliferation and survival contributing to disease progression and metastasis. In this study, we also detected unidentified genes in human melanoma expression studies and uncover new candidate drug targets for further testing in canine melanoma.

The promise of multi-omics and clinical data integration to identify and target personalized healthcare approaches in autism spectrum disorders

Complex diseases are caused by a combination of genetic and environmental factors, creating a difficult challenge for diagnosis and defining subtypes. This review article describes how distinct disease subtypes can be identified through integration and analysis of clinical and multi-omics data. A broad shift toward molecular subtyping of disease using genetic and omics data has yielded successful results in cancer and other complex diseases. To determine molecular subtypes, patients are first classified by applying clustering methods to different types of omics data, then these results are integrated with clinical data to characterize distinct disease subtypes. An example of this molecular-data-first approach is in research on Autism Spectrum Disorder (ASD), a spectrum of social communication disorders marked by tremendous etiological and phenotypic heterogeneity. In the case of ASD, omics data such as exome sequences and gene and protein expression data are combined with clinical data such as psychometric testing and imaging to enable subtype identification. Novel ASD subtypes have been proposed, such as CHD8, using this molecular subtyping approach. Broader use of molecular subtyping in complex disease research is impeded by data heterogeneity, diversity of standards, and ineffective analysis tools. The future of molecular subtyping for ASD and other complex diseases calls for an integrated resource to identify disease mechanisms, classify new patients, and inform effective treatment options. This in turn will empower and accelerate precision medicine and personalized healthcare.

Time Trends in Rates of Hodgkin Lymphoma Histologic Subtypes: True Incidence Changes or Evolving Diagnostic Practice?

BACKGROUND

Histologic subtypes of classical Hodgkin lymphoma [cHL; e.g., nodular sclerosis, mixed cellularity, not otherwise specified (NOS)] are epidemiologically and prognostically distinctive. Therefore, unexplained, ongoing incidence rate declines for mixed cellularity and increases for NOS require examination.

METHODS

We analyzed detailed histology-specific Hodgkin lymphoma incidence rates in 1992 through 2011 U.S. SEER data (n = 21,372) and reviewed a regional subset of 2007 through 2011 NOS pathology reports for insight into diagnostic practices.

RESULTS

cHL rates were stable until 2007, then decreased for whites [annual percent change (APC) and 95% confidence interval (CI), -3.6% (-5.6% to -1.5%)]. Nodular sclerosis rates declined after 2007 by 5.9% annually, with variation by gender, age, and race/ethnicity. In 1992 through 2011, mixed cellularity rates declined [APC -4.0% (-4.7% to -3.3%)], whereas NOS rates rose [5.3% (4.5%-6.2%)] overall and in most patient groups. The 2007-2011 NOS age-specific rates were more similar to mixed cellularity rates for 1992-1996 than 2007-2011. Trends in combined rates were minimal, supporting increasing misclassification of mixed cellularity, lymphocyte depletion, and specific nodular sclerosis subtypes as NOS. Eighty-eight of 165 reviewed NOS pathology reports addressed classification choice. Twenty (12.1%) justified the classification, 21 (12.7%) described insufficient biopsy material, and coders missed specific subtype information for 27 (16.4%).

CONCLUSION

Recent nodular sclerosis rate declines largely represent true incidence changes. Long-term rate decreases for mixed cellularity and other less common subtypes, and increases for NOS (comprising ∼30% of cHL cases in 2011), likely reflect changes in diagnostic and/or classification practice.

IMPACT

Diminishing histologic subtyping undermines future surveillance and epidemiologic study of Hodgkin lymphoma. Guideline-based use of excisional biopsies and more coding quality control are warranted.

CSF1R Protein Expression in Reactive Lymphoid Tissues and Lymphoma: Its Relevance in Classical Hodgkin Lymphoma

Tumour-associated macrophages (TAMs) have been associated with survival in classic Hodgkin lymphoma (cHL) and other lymphoma types. The maturation and differentiation of tissue macrophages depends upon interactions between colony-stimulating factor 1 receptor (CSF1R) and its ligands. There remains, however, a lack of consistent information on CSF1R expression in TAMs. A new monoclonal antibody, FER216, was generated to investigate CSF1R protein distribution in formalin fixed tissue samples from 24 reactive lymphoid tissues and 187 different lymphoma types. We also analysed the distribution of CSF1R+, CD68+ and CD163+ macrophages by double immunostaining, and studied the relationship between CSF1R expression and survival in an independent series of 249 cHL patients. CSF1R+ TAMs were less frequent in B-cell lymphocytic leukaemia and lymphoblastic B-cell lymphoma than in diffuse large B-cell lymphoma, peripheral T-cell lymphoma, angioimmunoblastic T-cell lymphoma and cHL. HRS cells in cHL and, with the exception of three cases of anaplastic large cell lymphoma, the neoplastic cells in NHLs, lacked detectable CSF1R protein. A CSF1R+ enriched microenvironment in cHL was associated with shorter survival in an independent series of 249 cHL patients. CSF1R pathway activation was evident in the cHL and inactivation of this pathway could be a potential therapeutic target in cHL cases.

Identifying gene disruptions in novel balanced de novo constitutional translocations in childhood cancer patients by whole-genome sequencing

Purpose

We applied whole genome sequencing to children diagnosed with neoplasms and found to carry apparently balanced constitutional translocations, to discover novel genic disruptions.

Methods

We applied SV calling programs CREST, Break Dancer, SV-STAT and CGAP-CNV, and developed an annotative filtering strategy to achieve nucleotide resolution at the translocations.

Results

We identified the breakpoints for t(6;12) (p21.1;q24.31) disrupting HNF1A in a patient diagnosed with hepatic adenomas and Maturity Onset Diabetes of the Young (MODY). Translocation as the disruptive event of HNF1A, a gene known to be involved in MODY3, has not been previously reported. In a subject with Hodgkin’s lymphoma and subsequent low-grade glioma, we identified t(5;18) (q35.1;q21.2), disrupting both SLIT3 and DCC, genes previously implicated in both glioma and lymphoma.

Conclusions

These examples suggest that implementing clinical whole genome sequencing in the diagnostic work-up of patients with novel but apparently balanced translocations may reveal unanticipated disruption of disease-associated genes and aid in prediction of the clinical phenotype.

Flow sorting and exome sequencing reveal the oncogenome of primary Hodgkin and Reed-Sternberg cells

Classical Hodgkin lymphoma (cHL) is characterized by sparsely distributed Hodgkin and Reed-Sternberg (HRS) cells amid reactive host background, complicating the acquisition of neoplastic DNA without extensive background contamination. We overcame this limitation by using flow-sorted HRS and intratumor T cells and optimized low-input exome sequencing of 10 patient samples to reveal alterations in genes involved in antigen presentation, chromosome integrity, transcriptional regulation, and ubiquitination. β-2-microglobulin (B2M) is the most commonly altered gene in HRS cells, with 7 of 10 cases having inactivating mutations that lead to loss of major histocompatibility complex class I (MHC-I) expression. Enforced wild-type B2M expression in a cHL cell line restored MHC-I expression. In an extended cohort of 145 patients, the absence of B2M protein in the HRS cells was associated with lower stage of disease, younger age at diagnosis, and better overall and progression-free survival. B2M-deficient cases encompassed most of the nodular sclerosis subtype cases and only a minority of mixed cellularity cases, suggesting that B2M deficiency determines the tumor microenvironment and may define a major subset of cHL that has more uniform clinical and morphologic features. In addition, we report previously unknown genetic alterations that may render selected patients sensitive to specific targeted therapies.

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

Despite the high cure rate in classical Hodgkin lymphoma (CHL), more accurate tailoring of upfront treatment is required to maximize cure while avoiding unnecessary short- and long-term treatment side effects. To this end, the unique tumor microenvironment of CHL has been searched extensively for prognostic biomarkers. Beyond targeted immunohistochemistry (IHC) studies, gene expression profiling (GEP) of diagnostic whole tissue biopsies has allowed a de novo approach to biomarker discovery. Among numerous candidate biomarkers, an association between the number of tumor-associated macrophages in the microenvironment and outcomes after ABVD (doxorubicin + bleomycin + vinblastine + dacarbazine) chemotherapy emerged, and multiple subsequent studies have validated this biological relationship using IHC. These studies have also defined key aspects for macrophage interrogation, including the characteristics of the CD68 and CD163 antibodies, appropriate scoring methodologies, and the identification of specific patient populations in which macrophage IHC may not be prognostic. The GEP studies also led to the development of gene expression-based prognostic models for advanced-stage CHL, with new technologies allowing reliable gene expression quantitation using RNA from routinely produced formalin-fixed paraffin-embedded biopsies. The bridge to predictive biomarkers that can be used reliably to inform upfront treatment selection requires further studies to demonstrate that these biomarkers can identify robustly, at diagnosis, patients at high risk of treatment failure with ABVD and that this risk may be overcome using alternative treatments.

MicroRNA signatures and treatment response in patients with advanced classical Hodgkin lymphoma

Although specific microRNA (miRNA) signatures in classical Hodgkin lymphoma (cHL) have been proposed, their relationship with clinical outcome remains unclear. Despite treatment advances, a substantial subset of patients with advanced cHL are refractory to standard therapies based on adriamycin and its variants. Global miRNA expression data of 29 advanced cHL patients and five cHL-derived cell lines were used to identify profiles from Hodgkin-Reed-Sternberg (HRS) cells and their non-tumoural microenvironment. A cHL-miRNA signature was identified with 234 miRNAs differentially expressed. A subset of these miRNAs was associated with outcome and selected for study in an independent set of 168 cHL samples using quantitative reverse transcription polymerase chain reaction. Multivariate Cox regression analyses including cross-validation with failure-free survival (FFS) as clinical endpoint revealed a miRNA signature with MIR21, MIR30E, MIR30D and MIR92B* that identified two risk-groups with significant differences in 5-year FFS (81% vs. 35.7%; P < 0.001). Additionally, functional silencing of MIR21 and MIR30D in L428 cells showed increased sensitivity to doxorubicin-induced apoptosis, pointing towards abnormalities of mitochondrial intrinsic and TP53-CDKN1A pathways as related to miRNA deregulation in cHL. These results suggest that clinical outcome in cHL is associated with a specific miRNA signature. Moreover, functional analyses suggest a role for MIR21 and MIR30D in cHL pathogenesis and therapeutic resistance.

Tumor associated macrophages in relapsed and refractory Hodgkin lymphoma

BACKGROUND

Growing evidence demonstrates that an increased number of CD68 positive tumor-associated macrophages (TAM) is associated with decreased survival in patients with newly diagnosed classic Hodgkin lymphoma (HL). However, the impact of TAM in relapsed and refractory disease is unknown.

DESIGN AND METHODS

To investigate whether the presence of elevated CD68 retains its prognostic significance in the relapsed and refractory setting, we analyzed pre-salvage biopsy specimens of 81 patients with relapsed and refractory HL using a tissue microarray. Scoring of CD68 was based on the percentage of CD68 positive TAM compared to the total number of cells in representative areas. The final percent of CD68 positivity for each case was based on the average of cores available for examination.

RESULTS

In a univariate analysis, we found that patients with elevated levels of CD68 positive TAM had inferior overall survival (OS) compared with patients who had lower CD68 levels. For patients undergoing autologous stem cell transplant after salvage treatment, elevated CD68 levels were predictive of both adverse OS and event free survival. However, after adjusting for other variables, increased CD68 positive TAM did not retain prognostic significance in a multivariate model.

CONCLUSIONS

In our dataset of primary refractory and relapsed Hodgkin lymphoma biopsy specimens, TAM infiltration is unable to definitively predict outcome. In order to validate these findings, TAM infiltration of relapsed and refractory specimens should be assessed prospectively and paired to initial Hodgkin lymphoma biopsies at diagnosis.

Prognostic role of tumor-associated macrophages and angiogenesis in classical Hodgkin lymphoma

We studied by immunohistochemistry CD68 + tumor-associated macrophages (TAMs) and angiogenesis in 121 consecutive cases of uniformly treated classical Hodgkin lymphoma (cHL). High TAM count showed a significant correlation with age ≥ 45, mixed cellularity subtype and high β₂-microglobulin level. Vessel density (VD) was unrelated to clinicopathological features, while a significant correlation was found between TAM count and VD. Patients with high TAMs showed a trend toward reduced progression-free survival and significantly shorter overall survival (OS). No correlation was found between VD and survival. At multivariate analysis, bulky disease was an independent predictor of reduced progression-free survival, while independent adverse prognostic factors for OS were male sex, age ≥ 45, advanced stage and bulky disease. High TAM count results in an adverse overall outcome in cHL and is significantly correlated to VD. Since VD has no prognostic relevance, the adverse effect of TAMs is presumably unrelated to angiogenesis.

Gene expression-based model using formalin-fixed paraffin-embedded biopsies predicts overall survival in advanced-stage classical Hodgkin lymphoma

PURPOSE

Our aim was to reliably identify patients with advanced-stage classical Hodgkin lymphoma (cHL) at increased risk of death by developing a robust predictor of overall survival (OS) using gene expression measured in routinely available formalin-fixed paraffin-embedded tissue (FFPET).

METHODS

Expression levels of 259 genes, including those previously reported to be associated with outcome in cHL, were determined by digital expression profiling of pretreatment FFPET biopsies from 290 patients enrolled onto the E2496 Intergroup trial comparing doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) and Stanford V regimens in locally extensive and advanced-stage cHL. A model for OS separating patients into low- and high-risk groups was produced using penalized Cox regression. The model was tested in an independent cohort of 78 patients enriched for treatment failure but otherwise similar to patients in a population-based registry of patients treated with ABVD. Weighted analysis methods generated unbiased estimates of predictor performance in the population-based registry.

RESULTS

A 23-gene outcome predictor was generated. The model identified a population at increased risk of death in the validation cohort. There was a 29% absolute difference in 5-year OS between the high- and low-risk groups (63% v 92%, respectively; log-rank P < .001; hazard ratio, 6.7; 95% CI, 2.6 to 17.4). The predictor was superior to the International Prognostic Score and CD68 immunohistochemistry in multivariate analyses.

CONCLUSION

A gene expression-based predictor, developed in and applicable to routinely available FFPET biopsies, identifies patients with advanced-stage cHL at increased risk of death when treated with standard-intensity up-front regimens.

Analyzing primary Hodgkin and Reed-Sternberg cells to capture the molecular and cellular pathogenesis of classical Hodgkin lymphoma

The pathogenesis of classical Hodgkin lymphoma (cHL), the most common lymphoma in the young, is still enigmatic, largely because its Hodgkin and Reed-Sternberg (HRS) tumor cells are rare in the involved lymph node and therefore difficult to analyze. Here, by overcoming this technical challenge and performing, for the first time, a genome-wide transcriptional analysis of microdissected HRS cells compared with other B-cell lymphomas, cHL lines, and normal B-cell subsets, we show that they differ extensively from the usually studied cHL cell lines, that the lost B-cell identity of cHLs is not linked to the acquisition of a plasma cell-like gene expression program, and that Epstein-Barr virus infection of HRS cells has a minor transcriptional influence on the established cHL clone. Moreover, although cHL appears a distinct lymphoma entity overall, HRS cells of its histologic subtypes diverged in their similarity to other related lymphomas. Unexpectedly, we identified 2 molecular subgroups of cHL associated with differential strengths of the transcription factor activity of the NOTCH1, MYC, and IRF4 proto-oncogenes. Finally, HRS cells display deregulated expression of several genes potentially highly relevant to lymphoma pathogenesis, including silencing of the apoptosis-inducer BIK and of INPP5D, an inhibitor of the PI3K-driven oncogenic pathway.

Role of immune escape mechanisms in Hodgkin's lymphoma development and progression: a whole new world with therapeutic implications

Hodgkin's lymphoma represents one of the most frequent lymphoproliferative syndromes, especially in young population. Although HL is considered one of the most curable tumors, a sizeable fraction of patients recur after successful upfront treatment or, less commonly, are primarily resistant. This work tries to summarize the data on clinical, histological, pathological, and biological factors in HL, with special emphasis on the improvement of prognosis and their impact on therapeutical strategies. The recent advances in our understanding of HL biology and immunology show that infiltrated immune cells and cytokines in the tumoral microenvironment may play different functions that seem tightly related with clinical outcomes. Strategies aimed at interfering with the crosstalk between tumoral Reed-Sternberg cells and their cellular partners have been taken into account in the development of new immunotherapies that target different cell components of HL microenvironment. This new knowledge will probably translate into a change in the antineoplastic treatments in HL in the next future and hopefully will increase the curability rates of this disease.

Three-dimensional Telomere Signatures of Hodgkin- and Reed-Sternberg Cells at Diagnosis Identify Patients with Poor Response to Conventional Chemotherapy

In classic Hodgkin lymphoma (HL) the malignant mononuclear Hodgkin (H) and multinuclear Reed-Sternberg (RS) cells are characterized by a distinct three-dimensional nuclear telomere organization with shortening of the telomere length and the formation of telomeric aggregates. We asked if the severity of these telomere changes correlates with the clinical behavior of the disease. We retrospectively evaluated three-dimensional telomere organization by quantitative fluorescent in situ hybridization (Q-FISH) of diagnostic biopsies from 16 patients who were good responders and compared them with 16 diagnostic biopsies of 10 patients with refractory or relapsing HL (eight initial biopsies, four confirming progressions, and four confirming relapses). The H cells from patients with refractory/relapsing disease contained a significantly higher percentage of very small telomeres (P = .027) and telomere aggregates (P = .032) compared with H cells of patients entering rapid remission. These differences were even more significant (P = .002 and P = .013, respectively) when comparing the eight initial diagnostic biopsies of refractory/relapsing HL with diagnostic biopsies of eight patients with ongoing long-lasting remission (mean of 47 months). This specific three-dimensional telomere Q-FISH signature identifies these highly aggressive mononuclear H cells at the first diagnostic biopsy and thus may offer a new molecular marker to optimize initial treatment.

The ratio of the absolute lymphocyte count to the absolute monocyte count is associated with prognosis in Hodgkin's lymphoma: correlation with tumor-associated macrophages

BACKGROUND

Although most patients with classical Hodgkin's lymphoma (cHL) have a long survival duration, the current risk stratification is imperfect. A recent study suggested a prognostic role for the peripheral blood absolute lymphocyte count/absolute monocyte count (ALC/AMC) ratio at diagnosis in cHL. It is intriguing to investigate the significance of the ALC/AMC ratio in relation to tumor-associated macrophages (TAMs), yet another prognostic factor for cHL.

METHODS

We examined the prognostic impact of the ALC, AMC, and ALC/AMC ratio in 312 cHL patients (median age, 37 years) using receiver operating characteristic curve analysis for optimal cutoff values, and compared these with TAM content.

RESULTS

The median follow-up was 65 months (range, 0.1-245 months). On univariate analysis, a low ALC/AMC ratio (<2.9) was correlated with a poorer overall survival (OS) outcome. A subgroup analysis of patients with limited-stage disease showed that the ALC/AMC ratio was significantly correlated with the OS time. Multivariate analysis showed the ALC/AMC ratio to be an independent prognostic factor for OS outcome. A Spearman correlation test of TAM content showed a negative correlation with the ALC/AMC ratio and a positive correlation with the peripheral blood macrophage percentage.

CONCLUSIONS

This study suggests that the ALC/AMC ratio may be a simple, inexpensive, and independent prognostic factor for OS outcome in patients with cHL and may have a role in the stratification of cHL patients in addition to the International Prognostic Score and TAM content.

Immunohistochemical markers for tumor associated macrophages and survival in advanced classical Hodgkin's lymphoma

A subset of patients with advanced classical Hodgkin's lymphoma is refractory to standard therapies. Therefore, it is relevant to identify new biologically-based prognostic markers. Recently, tumor associated macrophages have been proposed as a factor that predicts survival, although contradictory results have also been reported. Here we analyzed four macrophage markers (CD68, CD163, LYZ, and STAT1) using immunohistochemistry and automated quantification, in two independent series of advanced classical Hodgkin's lymphoma (n=266 and 103 patients, respectively). Our results did not confirm that specific macrophage immunohistochemical markers could be used as surrogates for gene expression profiling studies. Survival analyses did not show correlation between CD163, LYZ or STAT1 and either failure-free or disease-specific survival. There was an association between CD68 and disease-specific survival, but it was not consistent in both series. In conclusion, individual tumor associated macrophage markers cannot be used to predict outcome before technical standardization and prospective validation in independent series of patients with comparable stages and treatments.

CD163 versus CD68 in tumor associated macrophages of classical Hodgkin lymphoma

Classical Hodgkin lymphoma (CHL) is a B-cell lymphoproliferative disorder with a relatively good prognosis. A small but significant percentage of patients, however, will respond poorly to therapy. A recent gene expression profiling study has identified a macrophage signature which has been correlated with primary treatment failure, and immunohistochemical tissue microarray for CD68 was shown to reflect the gene signature as a potentially clinically useful marker to predict adverse prognosis.

We examined 44 cases of CHL, mostly nodular sclerosis subtype, in which the immunohistochemical stains for the histiocytic markers CD68 and CD163 were performed. The staining intensity was graded for each stain (< 5, 5-25, and > 25 percent of cells positive in the Hodgkin cell (HC) rich nodules) and background staining characteristics were recorded.

CD163 staining was lower than CD68 in HC rich nodules, with lower background staining (p 0.03). There was no significant difference between either CD68 or CD163 and disease recurrence in a subset (N = 41) of cases.

In conclusion, we demonstrate that CD163 staining is lower than CD68, with less non-specific staining of background inflammatory cells and Hodgkin cells, therefore is a better marker for tumor associated macrophages. However, we did not identify a correlation between staining for CD68 or CD163 and recurrence of disease.

Molecular Pathogenesis of Hodgkin's Lymphoma: Increasing Evidence of the Importance of the Microenvironment

Hodgkin's lymphoma (HL) represents the most common subtype of malignant lymphoma in young people in the Western world. Most patients can be cured with modern treatment strategies, although approximately 20% will die after relapse or progressive disease. The histologic hallmark of the disease is the presence of the characteristic Hodgkin Reed-Sternberg (HRS) cells in classical HL and so-called lymphocyte-predominant (LP) cells in nodular lymphocyte-predominant HL. HL is unique among all cancers because malignant cells are greatly outnumbered by reactive cells in the tumor microenvironment and make up only approximately 1% of the tumor. Expression of a variety of cytokines and chemokines by the HRS and LP cells is believed to be the driving force for an abnormal immune response, perpetuated by additional factors secreted by reactive cells in the microenvironment that help maintain the inflammatory milieu. The malignant HRS and LP cells manipulate the microenvironment, permitting them to develop their malignant phenotype fully and evade host immune attack. Gene expression signatures derived from non-neoplastic cells correlate well with response to initial and subsequent therapies, reflecting their functional relevance. Recent biomarker studies have added texture to clinical outcome predictors, and their incorporation into prognostic models may improve our understanding of the biologic correlates of treatment failure. Moreover, recent preclinical and clinical studies have demonstrated that the tumor microenvironment represents a promising therapeutic target, raising hope that novel treatment strategies focused on the interface between malignant and reactive cells will soon emerge.

Predicting treatment outcome in classical Hodgkin lymphoma: genomic advances

Classical Hodgkin lymphoma is considered a highly curable disease; however, 20% of patients cannot be cured with standard first-line chemotherapy and have a dismal outcome. Current clinical parameters do not allow accurate risk stratification, and personalized therapies are lacking. In fact, Hodgkin lymphoma (HL) is often over- or undertreated because of this lack of accurate risk stratification. In recent years, the early detection of chemoresistance by fluorodeoxyglucose positron emission tomography has become the most important prognostic tool in the management of HL. However, to date, no prognostic scores or molecular markers are available for the early identification of patients at very high risk of failure of induction therapy. In the last decade, many important advances have been made in understanding the biology of HL. In particular, the development of new molecular profiling technologies, such as SNP arrays, comparative genomic hybridization, and gene-expression profiling, have allowed the identification of new prognostic factors that may be useful for risk stratification and predicting response to chemotherapy. In this review, we focus on the prognostic tools and biomarkers that are available for newly diagnosed HL, and we highlight recent advances in the genomic characterization of classical HL and potential targets for therapy.

Targeting the microenvironment

The microenvironment in which cancer arises plays a critical role in tumorigenesis. Although previously regarded as an innocent bystander, evidence has accumulated over the past 10 years that the microenvironment contributes to tumor growth and progression by providing nutrients and survival signals, and protecting the tumor from normal immune responses and anticancer drugs. Exactly how normal stromal cells, whose function should be to suppress malignant growth, become co-opted into facilitating tumor development is only just beginning to be understood, but a complex story is emerging wherein tumor and stromal cells appear to co-evolve. A better understanding of tumor-stromal interactions and the molecular alterations that result in stromal dysfunction may help to identify patients who will benefit from either more aggressive or risk-adapted therapy regimens, and/or novel compounds that disrupt the tumor microenvironment and re-establishing normal control mechanisms.

Recent Advances in the Pathobiology of Hodgkin's Lymphoma: Potential Impact on Diagnostic, Predictive, and Therapeutic Strategies

From its first description by Thomas Hodgkin in 1832, Hodgkin's disease, now called Hodgkin's lymphoma, has continued to be a fascinating neoplasm even to this day. In this review, historical aspects, epidemiology, diagnosis, tumor biology, new observations related to host-microenvironment interactions, gene copy number variation, and gene expression profiling in this complex neoplasm are described, with an exploration of chemoresistance mechanisms and potential novel therapies for refractory disease.

Gene Expression Profiling for In Silico Microdissection of Hodgkin's Lymphoma Microenvironment and Identification of Prognostic Features

Gene expression profiling studies based on DNA microarrays have demonstrated their ability to define the interaction pathways between neoplastic and nonmalignant stromal cells in cancer tissues. During the past ten years, a number of approaches including microdissection have tried to resolve the variability in DNA microarray measurements stemming from cancer tissue sample heterogeneity. Another approach, designated as virtual or in silico microdissection, avoids the laborious and time-consuming step of anatomic microdissection. It consists of confronting the gene expression profiles of complex tissue samples to those of cell lines representative of different cell lineages, different differentiation stages, or different signaling pathways. This strategy has been used in recent studies aiming to analyze microenvironment alterations using gene expression profiling of nonmicrodissected classical Hodgkin lymphoma tissues in order to generate new prognostic factors. These recent contributions are detailed and discussed in the present paper.

A molecular risk score based on 4 functional pathways for advanced classical Hodgkin lymphoma

Despite improvement in the treatment of advanced classical Hodgkin lymphoma, approximately 30% of patients relapse or die as result of the disease. Current predictive systems, determined by clinical and analytical parameters, fail to identify these high-risk patients accurately. We took a multistep approach to design a quantitative reverse-transcription polymerase chain reaction assay to be applied to routine formalin-fixed paraffin-embedded samples, integrating genes expressed by the tumor cells and their microenvironment. The significance of 30 genes chosen on the basis of previously published data was evaluated in 282 samples (divided into estimation and validation sets) to build a molecular risk score to predict failure. Adequate reverse-transcription polymerase chain reaction profiles were obtained from 262 of 282 cases (92.9%). Best predictor genes were integrated into an 11-gene model, including 4 functional pathways (cell cycle, apoptosis, macrophage activation, and interferon regulatory factor 4) able to identify low- and high-risk patients with different rates of 5-year failure-free survival: 74% versus 44.1% in the estimation set (P < .001) and 67.5% versus 45.0% in the validation set (P = .022). This model can be combined with stage IV into a final predictive model able to identify a group of patients with very bad outcome (5-year failure-free survival probability, 25.2%).

Tumor-associated macrophages and survival in classic Hodgkin's lymphoma

BACKGROUND

Despite advances in treatments for Hodgkin's lymphoma, about 20% of patients still die from progressive disease. Current prognostic models predict the outcome of treatment with imperfect accuracy, and clinically relevant biomarkers have not been established to improve on the International Prognostic Score.

METHODS

Using gene-expression profiling, we analyzed 130 frozen samples obtained from patients with classic Hodgkin's lymphoma during diagnostic lymph-node biopsy to determine which cellular signatures were correlated with treatment outcome. We confirmed our findings in an independent cohort of 166 patients, using immunohistochemical analysis.

RESULTS

Gene-expression profiling identified a gene signature of tumor-associated macrophages that was significantly associated with primary treatment failure (P=0.02). In an independent cohort of patients, we found that an increased number of CD68+ macrophages was correlated with a shortened progression-free survival (P=0.03) and with an increased likelihood of relapse after autologous hematopoietic stem-cell transplantation (P=0.008), resulting in shortened disease-specific survival (P=0.003). In multivariate analysis, this adverse prognostic factor outperformed the International Prognostic Score for disease-specific survival (P=0.003 vs. P=0.03). The absence of an elevated number of CD68+ cells in patients with limited-stage disease defined a subgroup of patients with a long-term disease-specific survival of 100% with the use of current treatment strategies.

CONCLUSIONS

An increased number of tumor-associated macrophages was strongly associated with shortened survival in patients with classic Hodgkin's lymphoma and provides a new biomarker for risk stratification.

Inflammation and tissue repair markers distinguish the nodular sclerosis and mixed cellularity subtypes of classical Hodgkin's lymphoma

Background:

Classical Hodgkin's lymphoma (cHL), although a malignant disease, has many features in common with an inflammatory condition. The aim of this study was to establish the molecular characteristics of the two most common cHL subtypes, nodular sclerosis (NS) and mixed cellularity (MC), based on molecular profiling and immunohistochemistry, with special reference to the inflammatory microenvironment.

Methods:

We analysed 44 gene expression profiles of cHL whole tumour tissues, 25 cases of NS and 19 cases of MC, using Affymetrix chip technology and immunohistochemistry.

Results:

In the NS subtype, 152 genes showed a significantly higher expression, including genes involved in extracellular matrix (ECM) remodelling and ECM deposition similar to wound healing. Among these were SPARC, CTSK and COLI. Immunohistochemistry revealed that the NS-related genes were mainly expressed by macrophages and fibroblasts. Fifty-three genes had a higher expression in the MC subtype, including several inflammation-related genes, such as C1Qα, C1Qβ and CXCL9. In MC tissues, the C1Q subunits were mainly expressed by infiltrating macrophages.

Conclusions and interpretations:

We suggest that the identified subtype-specific genes could reflect different phases of wound healing. Our study underlines the potential function of infiltrating macrophages in shaping the cHL tumour microenvironment.

Hodgkin lymphoma: an update on its biology with new insights into classification

In the past few years, there has been a greater understanding of the spectrum and biology of Hodgkin lymphoma (HL). In standard texts, HL is classified as 2 distinct entities, namely nodular lymphocyte-predominant HL and classical HL (CHL). However, recent evidence suggests that CHL is not a single disease. Although the mixed cellularity and lymphocyte-depleted subtypes might be part of a biologic continuum, the nodular sclerosis subtype has a distinct epidemiology, clinical presentation, and histology. Nodular sclerosis HL might also be related to primary mediastinal B-cell lymphoma and mediastinal gray-zone lymphomas. We present an update on the pathobiology of HL and discuss these biologic and clinical differences in this review.

A TaqMan low-density array to predict outcome in advanced Hodgkin's lymphoma using paraffin-embedded samples

PURPOSE

Despite major advances in the treatment of classic Hodgkin's lymphoma (cHL), approximately 30% of patients in advanced stages may eventually die as result of the disease, and current methods to predict prognosis are rather unreliable. Thus, the application of robust techniques for the identification of biomarkers associated with treatment response is essential if new predictive tools are to be developed.

EXPERIMENTAL DESIGN

We used gene expression data from advanced cHL patients to identify transcriptional patterns from the tumoral cells and their nonneoplastic microenvironment, associated with lack of maintained treatment response. Gene-Set Enrichment Analysis was used to identify functional pathways associated with unfavorable outcome that were significantly enriched in either the Hodgkin's and Reed-Sternberg cells (regulation of the G2-M checkpoint, chaperones, histone modification, and signaling pathways) or the reactive cell microenvironment (mainly represented by specific T-cell populations and macrophage activation markers).

RESULTS

To explore the pathways identified previously, we used a series of 52 formalin-fixed paraffin-embedded advanced cHL samples and designed a real-time PCR-based low-density array that included the most relevant genes. A large majority of the samples (82.7%) and all selected genes were analyzed successfully with this approach.

CONCLUSIONS

The results of this assay can be combined in a single risk score integrating these biological pathways associated with treatment response and eventually used in a larger series to develop a new molecular outcome predictor for advanced cHL.