Tumor microenvironment contribution to checkpoint blockade therapy: lessons learned from Hodgkin lymphoma.

Classic Hodgkin lymphoma (cHL) is characterized by a tumor microenvironment (TME) containing inflammatory/immune cells. Follicular lymphoma, mediastinal gray zone lymphoma, and diffuse large B-cell lymphomas may show a TME containing inflammatory/immune cells, but the TMEs are quite different. In B-cell lymphomas and cHL, programmed cell death 1 (PD-1)-PD ligand 1 pathway blockade drugs differ in their effectiveness among patients with refractory/relapsed disease. Further research should explore innovative assays that could reveal which molecules influence sensitivity or resistance to therapy in an individual patient.

Hematologic cancers in individuals infected by HIV.

HIV infection increases cancer risk and is linked to cancers associated to infectious agents classified as carcinogenic to humans by the International Agency for Research on Cancer. Lymphomas represent one of the most frequent malignancies among individuals infected by HIV. Diffuse large B-cell lymphoma remains a leading cancer after the introduction of combined antiretroviral therapy (cART). The incidence of other lymphomas including Burkitt lymphoma, primary effusion lymphomas, and plasmablastic lymphoma of the oral cavity remain stable, whereas the incidence of Hodgkin lymphoma and Kaposi sarcoma-associated herpesvirus (KSHV)-associated multicentric Castleman disease has increased. The heterogeneity of lymphomas in individuals infected by HIV likely depends on the complexity of involved pathogenetic mechanisms (ie, HIV-induced immunosuppression, genetic abnormalities, cytokine dysregulation, and coinfection with the gammaherpesviruses Epstein-Barr virus and KSHV) and the dysregulation of the immune responses controlling these viruses. In the modern cART era, standard treatments for HIV-associated lymphoma including stem cell transplantation in relapsed/refractory disease mirror that of the general population. The combination of cART and antineoplastic treatments has resulted in remarkable prolongation of long-term survival. However, oncolytic and immunotherapic strategies and therapies targeting specific viral oncogenes will need to be developed.

HIV-related lymphomas.

PURPOSE OF REVIEW: To summarize the recent evidence on the pathology, current standard of care and recent advances in the treatment of HIV-related lymphomas. RECENT FINDINGS: Lymphomas remain a major cause of morbidity and mortality in people living with HIV, even in the era of combination antiretroviral therapy (cART). However, treatment outcomes for these malignancies have improved in recent decades, due to full-dose chemotherapy, effective cART and supportive care. Recent advances include the identification of novel driving signaling pathways as promising molecular targets to improve lymphoma outcomes. SUMMARY: Patients with HIV-related lymphomas who receive effective cART should be treated like the general population.

Are EBV-related and EBV-unrelated Hodgkin lymphomas different with regard to susceptibility to checkpoint blockade?

Epstein-Barr virus (EBV)-related and EBV-unrelated classical Hodgkin lymphomas (cHLs) are morphologically and phenotypically indistinguishable. However, the tumor microenvironment of EBV-related cHLs contains higher numbers of macrophages and higher expression levels of PD-L1 than that of EBV-unrelated cHLs. Moreover, viral oncoprotein LMP1 may sustain an immunosuppressive microenvironment by inducing/enhancing production of immunosuppressive cytokines and the expression of PD-1. The presence of enhanced immunosuppressive features in EBV-related cHL should make EBV-related cHL patients more susceptible to checkpoint blockade.

A lymphomagenic role for HIV beyond immune suppression?

Despite the immune reconstitution promoted by combined antiretroviral therapy (cART), lymphomas still represent the most common type of cancer in HIV-infected individuals. Cofactors related to immunodeficiency such as oncogenic viruses, chronic antigenic stimulation, and cytokine overproduction are thought to be the main drivers of HIV lymphomagenesis, although the current scenario does not convincingly explain the still-high incidence of lymphomas and the occurrence of peculiar lymphoma histotypes in HIV-infected patients under cART. Recent findings are challenging the current view of a mainly indirect role of HIV in lymphoma development and support the possibility that HIV may directly contribute to lymphomagenesis. In fact, mechanisms other than immune suppression involve biologic effects mediated by HIV products that are secreted and accumulate in lymphoid tissues, mainly within lymph node germinal centers. Notably, HIV-infected patients with lymphomas, but not those not affected by these tumors, were recently shown to carry HIV p17 protein variants with enhanced B-cell clonogenic activity. HIV p17 protein variants were characterized by the presence of distinct insertions at the C-terminal region of the protein responsible for a structural destabilization and the acquisition of novel biologic properties. These data are changing the current paradigm assuming that HIV is only indirectly related to lymphomagenesis. Furthermore, these recent findings are consistent with a role of HIV as a critical microenvironmental factor promoting lymphoma development and pave the way for further studies that may lead to the design of more effective strategies for an early identification and improved control of lymphomas in the HIV setting.

Role of HIV-1 matrix protein p17 variants in lymphoma pathogenesis.

Although in decline after successful anti-HIV therapy, B-cell lymphomas are still elevated in HIV-1-seropositive (HIV+) persons, and the mechanisms are obscure. The HIV-1 matrix protein p17 persists in germinal centers long after HIV-1 drug suppression, and some p17 variants (vp17s) activate Akt signaling and promote growth of transformed B cells. Here we show that vp17s derived from four of five non-Hodgkin lymphoma (NHL) tissues from HIV+ subjects display potent B-cell growth-promoting activity. They are characterized by amino acid insertions at position 117-118 (Ala-Ala) or 125-126 (Gly-Asn or Gly-Gln-Ala-Asn-Gln-Asn) among some other mutations throughout the sequence. Identical dominant vp17s are found in both tumor and plasma. Three of seven plasma samples from an independent set of NHL cases manifested multiple Ala insertions at position 117-118, and one with the Ala-Ala profile also promoted B-cell growth and activated Akt signaling. Ultradeep pyrosequencing showed that vp17s with C-terminal insertions are more frequently detected in plasma of HIV+ subjects with than without NHL. Insertion of Ala-Ala at position 117-118 into reference p17 (refp17) was sufficient to confer B-cell growth-promoting activity. In contrast, refp17 bearing the Gly-Asn insertion at position 125-126 did not, suggesting that mutations not restricted to the C terminus can also account for this activity. Biophysical analysis revealed that the Ala-Ala insertion mutant is destabilized compared with refp17, whereas the Gly-Asn form is stabilized. This finding provides an avenue for further exploration of structure function relationships and new treatment strategies in combating HIV-1-related NHL.

The impact of EBV and HIV infection on the microenvironmental niche underlying Hodgkin lymphoma pathogenesis.

The pathogenesis of classical Hodgkin lymphoma (cHL) is still enigmatic, largely because its tumor cells, the so-called Hodgkin and Reed-Stenberg (HRS) cells, invariably reside in a prominent reactive microenvironment, are rare and therefore difficult to analyze. On the other hand, the broadly investigated cHL-derived cell lines are not unequivocally considered as suitable and representative models for this puzzling disease. Based on current knowledge, it appears that the cross talk between the tumor cells and the reactive infiltrate of the microenvironment is complex and that multiple mechanisms occur, making cHL a very heterogeneous disease. In 20-40% of cHL cases, HRS cells carry a monoclonal infection by Epstein Barr virus (EBV), which is considered a tumor-initiating factor. In these cases, EBV shows a latency type II infection pattern with the expression of latent membrane protein-1 (LMP-1), a viral oncoprotein that mimics CD40 activation. This scenario is particularly intriguing for the pathogenesis of cHL arising in HIV-infected patients, which, for still obscure reasons, is invariably EBV-associated with LMP-1 expression in HRS cells. Recent evidences are consistent with the occurrence of different pathogenic pathways variably triggered by virus infections (EBV and HIV), genetic alterations, and interactions with critical microenvironmental components. This review focuses on the different microenvironmental niches that characterize cHL of the general population as well as cases of HIV-infected patients. A more comprehensive understanding of the complex interplay existing between HRS and tumor microenvironment is pivotal for the development of more effective treatments, particularly for relapsed or refractory diseases.

Microenvironment and HIV-related lymphomagenesis.

Patients with HIV infection are at increased risk of developing non-Hodgkin lymphoma and Hodgkin lymphoma. While the pathogenesis of these lymphomas is incompletely understood, evidence indicates that immune deregulation, genetic alterations and cytokine production play an important role in HIV lymphomagenesis. The lymphoma microenvironment in this heterogeneous group of lymphomas plays an equally critical role in their development, growth and progression. Important components of the microenvironment in HIV-related lymphomas include EBV and/or HHV-8 coinfection, reactive inflammatory cells, tumor microvasculature, and soluble factors. This paper provides a brief overview of HIV-related lymphomas and focuses on their lymphomagenesis and microenvironment.

Microenvironmental abnormalities induced by viral cooperation: Impact on lymphomagenesis.

When stringent criteria have been used, the Epstein Barr virus (EBV), the Kaposi's sarcoma herpesvirus (KSHV), human immunodeficiency virus type 1 (HIV-1) and human hepatitis C virus (HCV) have been identified with sufficient evidence to be causative agents of non-Hodgkin's Lymphomas. Initially, single viral infection was considered fully responsible for the oncogenic properties of each virus, while it is now established that in many cases, multiple viral agents collaborate as cofactors in inducing lymphomas, especially in the presence of HIV-dependent immunodeficiency. Viruses cooperate by using their specific pathogenetic mechanisms in different combinations. The aim of this review is to describe the cooperation between different viruses in the development of lymphomas including the evidences supporting their pathogenetic role. Viral cooperation, a mechanism by which different viruses coinfecting human tissues have synergistic or regulatory effects on carcinogenesis, targets neoplastic B cells as well as cells of the microenvironment, such as reactive T-cells, B cells and macrophages, as well as non-immune cells such as endothelial cells, that contribute to tumor microenvironment. The most important viral genes involved in cooperation include HIV-1 tat and vpu, EBV LMP-1 and EBNA-2 and KSHV KIE2, Rta and LANA. Lymphomagenesis related to viral cooperation represents an interesting topic where microenvironmental abnormalities may be particularly relevant, particularly because antiviral targeted therapies and therapies producing the reconstitution of the immune system may constitute areas of interest aiming at improving the outcome of virus associated lymphomas. While the immune component of the lymphoma microenvironment can be easily studied by immunological and molecular techniques, the definition of the non-immune component of the lymphoma microenvironment is largely incomplete and may be the issue of future investigations. Understanding the pathogenetic role of viral infection in specific malignancies and defining microenvironmental abnormalities and mechanisms of viral carcinogenesis are important steps toward precise diagnosis and accurate treatment strategies for HIV-associated cancers.

Primary refractory and early-relapsed Hodgkin's lymphoma: strategies for therapeutic targeting based on the tumour microenvironment.

Classical Hodgkin's lymphoma (cHL), a distinct disease entity with characteristic clinical and pathological features, accounts for approximately 10% of all malignant lymphomas. cHL can be considered a prototype model for how the tumour microenvironment influences cancer pathogenesis. Cellular components of the cHL microenvironment express molecules involved in cancer cell growth and survival, such as CD30L or CD40L. Moreover, several signal transduction pathways that are critical for the proliferation and survival of neoplastic Hodgkin Reed-Sternberg (HRS) cells, including NF-κB, JAK-STAT, PI3K-AkT and ERK, are deregulated in cHL. Although most patients can be cured with modern treatment strategies, approximately a quarter experience either primary or secondary chemorefractoriness or disease relapse, thus requiring novel treatments. Preclinical and clinical evidence has elucidated a complex crosstalk between malignant HRS cells and the reactive cells of the microenvironment, which suggests that novel therapeutic approaches capable of targeting HRS cells along with reactive cells might overcome chemorefractoriness. In the near future, these novel therapies will also be tested in chemosensitive patients, to reduce the long-term toxicity of chemo-radiotherapy.

KSHV-associated multicentric Castleman disease: A tangle of different entities requiring multitarget treatment strategies.

Multicentric Castleman Disease (MCD) is a lymphoproliferative disorder presenting with heterogeneous pathological and clinical features. It comprises disease entities with a complex aetiology and overlapping pathogenesis. MCD can be found in association with HIV infection, plasma-cell dyscrasias, Kaposi sarcoma (KS), B-cell lymphomas including primary effusion lymphoma (PEL) and its solid variant, and Hodgkin lymphoma. In KSHV-associated MCD cases, a common association is KS and a specific variant of lymphoma referred to as "plasmablastic lymphoma," also called "large B-cell lymphoma arising in KSHV-associated MCD" lacking EBV infection. MCD is often referred to as human interleukin-6 (hIL-6) syndrome, since an overproduction of IL-6 occurs in MCD-associated diseases as well as in MCD itself. hIL-6 and a viral IL-6 (vIL-6) homolog encoded by KSHV can independently or together lead to flares of KSHV-associated MCD. Recently, a new clinical entity was proposed to describe a severe systemic infection/reactivation of KSHV: KSHV inflammatory syndrome (KICS). KICS may contribute in inducing the inflammatory symptoms seen in some patients with severe KS or PEL. The precise relationship of KICS to KSHV-associated MCD is unclear and it is possible that KICS may be prodromal symptoms to frank KSHV-associated MCD. Options for treatment of KSHV-associated MCD and related diseases include monoclonal antibodies, chemotherapy, immune modulators, virus-activated cytotoxic therapy and antiviral therapies. A comprehensive understanding of the intricacies of the HIV-KSHV coinfection will probably lead to additional advances in therapy and managements for these disorders.

A natural HIV p17 protein variant up-regulates the LMP-1 EBV oncoprotein and promotes the growth of EBV-infected B-lymphocytes: implications for EBV-driven lymphomagenesis in the HIV setting.

Human immunodeficiency virus p17 matrix protein is released by infected cells and may accumulate within lymphoid tissues where it may deregulate the biological activities of different cell populations by binding to CXCR1 and CXCR2 cellular receptors. S75X, a natural p17 variant, was recently shown to enhance the malignant properties of lymphoma cells. We investigated a reference p17 protein and the S75X variant for their ability to bind to Epstein-Barr virus (EBV)-infected primary and fully transformed B-lymphocytes and trigger downstream effects of potential pathogenic relevance. We demonstrate that EBV infection of primary B-lymphocytes or the ectopic expression of the latent membrane protein-1 viral oncoprotein in EBV-negative B-cells up-regulates CXCR2, but not CXCR1. Multispectral imaging flow cytometry showed that EBV-infected primary B-cells more efficiently bind and internalize p17 proteins as compared with activated B-lymphocytes. The S75X variant bound more efficiently to EBV-infected primary and fully transformed B-lymphocytes compared with reference p17, because of a higher affinity to CXCR2, and enhanced the proliferation of these cells, an effect associated with cyclin D2 and D3 up-regulation and increased interleukin-6 production. Notably, the S75X variant markedly up-regulated latent membrane protein-1 expression at both mRNA and protein levels and enhanced the activation of Akt, ERK1/2 and STAT3 signaling, thereby contributing to EBV(+) B-cell growth promotion. These results indicate that EBV infection sensitizes B-lymphocytes to CXCR2-mediated effects of p17 proteins and provide evidence supporting a possible contribution of natural p17 variants to EBV-driven lymphomagenesis in the human immunodeficiency virus setting.

Primary effusion lymphoma: secretome analysis reveals novel candidate biomarkers with potential pathogenetic significance.

Primary effusion lymphoma (PEL) is a rare B-cell neoplasm in which tumor cells are consistently infected by Kaposi's sarcoma-associated herpesvirus and usually grow in body cavities without tumor mass formation. To detect new proteins related to pathogenesis, four established cell lines from PEL (CRO-AP2, CRO-AP3, CRO-AP5, and CRO-AP6) were characterized by proteomics analysis of the secretome. The secretomes were analyzed using two complementary mass spectrometry platforms: liquid chromatography-mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight-based approaches. Among 266 proteins identified from the proteomics analysis, 139 were considered as predicted secreted. Twenty proteins were specifically secreted by PEL cell lines after comparison with secretomes of human cell lines representative of diverse solid tumors and leukemias. More important, 27 additional proteins were shared by all CRO-AP PEL cell lines. The presence of these proteins was confirmed by IHC in CRO-AP cell lines and in six other PEL cell lines, four PEL clinical samples, and three extracavitary Kaposi's sarcoma-associated herpesvirus-positive solid lymphomas included for comparative analysis. Functional classification showed that PEL cell secretomes were enriched in proteins specifically involved in inflammation/immune response, growth/cell cycle, and mRNA processing, in addition to structural/matrix proteins and proteins with enzymatic activity.

Activated DDR1 increases RS cell survival.

In this issue of Blood, Cader et al show that tumor microenvironment promotes Epstein-Barr virus (EBV)-driven lymphomagenesis in Hodgkin lymphoma by a novel pathway involving latent membrane protein 1 (LMP1) and discoidin domain receptor 1 (DDR1), which is activated by collagen(s) and contributes to the survival of Reed-Sternberg (RS) cells.

Lymphomas occurring specifically in HIV-infected patients: from pathogenesis to pathology.

Lymphomas that develop in HIV positive patients are predominantly aggressive B-cell malignancies. The most common HIV-associated lymphomas are Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL). Lymphomas that occur specifically in HIV positive patients include primary effusion lymphoma (PEL) and its solid variants, plasmablastic lymphoma of the oral cavity type and lymphoma associated with Kaposi sarcoma herpesvirus (KSHV)-related multicentric Castleman disease. These lymphomas, together with BL and immunoblastic lymphoma subtypes with plasmacytoid differentiation, carry Epstein-Barr virus (EBV) infection and display a phenotype related to plasma cells. Globally, EBV is identified in the neoplastic cells of approximately 40% of HIV-associated lymphomas, but the detection of EBV varies considerably with the site of presentation and the histological subtype. EBV infection occurs in 80-100% of primary central nervous system lymphomas and PELs, 80% of DLBCLs with immunoblastic-plasmacytoid features, and 30-50% of BL-plasmacytoid. KSHV is specifically associated with PEL, which usually occurs in a setting of profound immunosuppression. Current knowledge about HIV-associated lymphomas can be summarized as follows: (1) lymphomas specifically occurring in patients with HIV infection are closely linked to other viral diseases; (2) most of these lymphomas exhibit plasmablastic differentiation.

Interplay among viral antigens, cellular pathways and tumor microenvironment in the pathogenesis of EBV-driven lymphomas.

Epstein-Barr virus (EBV) is a ubiquitous human γ-herpes virus that has established an elegant strategy to persist as a life-long asymptomatic infection in memory B lymphocytes. EBV has potent transforming properties for B lymphocytes and it is pathogenically associated with a variety of lymphomas of B or NK/T cell origin. The viral latency programs expressed can hijack or deregulate cellular pathways critical for cell proliferation and survival, while impairing anti-viral immune responses. Similar effects may also be induced by EBV-encoded micro-RNAs, which may have a pathogenic role particularly in lymphomas showing a restricted expression of viral proteins. Of note, recent data have challenged the view that only the EBV latency is relevant for lymphomagenesis, suggesting that lytic EBV replication may also contribute to the development of EBV-associated lymphoproliferations. The recent advances in the elucidation of the mechanisms underlying EBV-induced cell transformation and immune evasion are providing the rationale for innovative and tailored treatment approaches for EBV-driven lymphomas.

The evolving scenario of non-AIDS-defining cancers: challenges and opportunities of care.

BACKGROUND: The impact of highly active antiretroviral therapies (HAART) on the risk of non-AIDS-defining cancers (NADCs) and the role of biological and clinical factors in their pathogenesis are debated issues. The purpose of this review is to examine the epidemiology, etiology, and not-yet-defined pathogenic characteristics of NADCs and discuss topics such as treatment strategies, comorbidity, and multidrug interactions. Four types of NADCs that deserve special attention are examined: anal cancer, Hodgkin lymphoma (HL), hepatocellular carcinoma, and lung cancer. METHODS: The PubMed database and the Cochrane Library were searched by focusing on NADCs and on the association among NADCs, HAART, aging, and/or chronic inflammation. All articles were reviewed to identify those reporting variables of interest. RESULTS: NADC incidence is twofold higher in patients with HIV/AIDS than in the corresponding general population, and this elevated risk persists despite the use of HAART. The mechanisms that HIV may use to promote the development of NADCs are presently unclear; immunological mechanisms, either immunodeficiency and/or immunoactivation, may play a role. CONCLUSION: Recent clinical studies have suggested that equivalent antineoplastic treatment is feasible and outcome can be similar in HIV-infected patients on HAART compared with uninfected patients for the treatment of HL and anal and lung cancers. However, patients with advanced HIV disease and/or aging-related comorbidities are likely to experience worse outcomes and have poorer tolerance of therapy compared with those with less advanced HIV disease.