High-dose zidovudine plus valganciclovir for Kaposi sarcoma herpesvirus-associated multicentric Castleman disease: a pilot study of virus-activated cytotoxic therapy

Local radiotherapy for chemotherapy-refractory Kaposi's sarcoma in an HIV-infected patient: A case report and literature review

Human immunodeficiency virus-associated Kaposi's sarcoma (HIV-KS) is a well-documented vascular tumor with a pathogenesis involving human herpesvirus-8 (HHV-8) infection. While antiretroviral therapy (ART) and chemotherapy are effective for treating most KS cases, some become refractory. In this report, we present a case of a 58-year-old man with refractory HIV-KS treated with ART and chemotherapy. Chemotherapy was eventually discontinued due to an adverse reaction, and the patient presented with painful plantar lesions that impaired ambulation. With the exclusion of visceral metastases, localized radiotherapy was administered, which resulted in significant cosmetic and functional improvements. The patient regained ambulation and lived independently, receiving additional radiotherapy as needed. This case underscores the potential use of radiotherapy for the treatment of ART-resistant KS, particularly when the patient is unresponsive to conventional chemotherapy. It also highlights the need for future research in this area.

Discovery of a small-molecule inhibitor of KSHV lytic replication from the MMV pandemic response box

Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent for primary effusion lymphoma (PEL), multicentric Castleman's disease (MCD) and Kaposi's sarcoma (KS). KSHV is one of the oncoviruses that contribute to 1.5 million new infection-related cancer cases annually. Currently, there are no targeted therapies for KSHV-associated diseases. Through the development of a medium-throughput phenotype-based ELISA screening platform based on KSHV ORF57 protein detection, we screened the Medicines for Malaria Venture (MMV) Pandemic Response Box for non-cytotoxic inhibitors of KSHV lytic replication. MMV1645152 was identified as a promising inhibitor of KSHV lytic replication, suppressing KSHV immediate-early and late lytic gene expression and blocking the production of infectious KSHV virion particles at non-cytotoxic concentrations in cell line models of KSHV infection with or without EBV coinfection. MMV1645152 is a promising hit compound for the development of future therapeutic agents against KSHV-associated malignancies.

The clinical picture of Castleman disease: a systematic review and meta-analysis

ABSTRACT

Castleman disease (CD) encompasses a spectrum of rare disorders, including unicentric CD (UCD), idiopathic multicentric CD (iMCD), and human herpesvirus 8-associated MCD (HHV8+ MCD). We performed a systematic review of publications reporting ≥5 cases of CD between 1995 and 2021, following preferred reporting items for systematic reviews and meta-analyses guidelines, to describe and compare subtypes. We extracted data on clinical symptoms and laboratory parameters as stated in international consensus diagnostic criteria for iMCD and estimated the frequency of each criterion using meta-analyses. We analyzed 32 studies describing 559 UCD, 1023 iMCD, and 416 HHV8+ MCD cases. Although many symptoms and laboratory abnormalities occurred at similar rates in patients with iMCD and HHV8+ MCD, patients with HHV8+ MCD had significantly higher rates of constitutional symptoms (46.6% vs 98.6%; P = .038) and splenomegaly (48.2% vs 89.2%; P = .031). Renal dysfunction was significantly more common in patients with iMCD than in patients with HHV8+ MCD before adjustment (36.9% vs 17.4%; P = .04; adjusted P = .1). Patients with UCD had lower rates of symptoms and laboratory abnormalities, although these were present in 20% of patients and were particularly pronounced in pediatric UCD. There are many similarities in the symptomatology of iMCD and HHV8+ MCD; many patients experience constitutional symptoms and organ dysfunction. Differences between these subtypes likely reflect differences in pathophysiology and/or comorbidity burdens.

HIV-associated cancers and lymphoproliferative disorders caused by Kaposi sarcoma herpesvirus and Epstein-Barr virus

SUMMARYWithin weeks of the first report of acquired immunodeficiency syndrome (AIDS) in 1981, it was observed that these patients often had Kaposi sarcoma (KS), a hitherto rarely seen skin tumor in the USA. It soon became apparent that AIDS was also associated with an increased incidence of high-grade lymphomas caused by Epstein-Barr virus (EBV). The association of AIDS with KS remained a mystery for more than a decade until Kaposi sarcoma-associated herpesvirus (KSHV) was discovered and found to be the cause of KS. KSHV was subsequently found to cause several other diseases associated with AIDS and human immunodeficiency virus (HIV) infection. People living with HIV/AIDS continue to have an increased incidence of certain cancers, and many of these cancers are caused by EBV and/or KSHV. In this review, we discuss the epidemiology, virology, pathogenesis, clinical manifestations, and treatment of cancers caused by EBV and KSHV in persons living with HIV.

The complete Kaposi sarcoma-associated herpesvirus genome induces early-onset, metastatic angiosarcoma in transgenic mice

Kaposi sarcoma (KS) is the most common cancer in persons living with HIV. It is caused by KS-associated herpesvirus (KSHV). There exists no animal model for KS. Pronuclear injection of the 170,000-bp viral genome induces early-onset, aggressive angiosarcoma in transgenic mice. The tumors are histopathologically indistinguishable from human KS. As in human KS, all tumor cells express the viral latency-associated nuclear antigen (LANA). The tumors transcribe most viral genes, whereas endothelial cells in other organs only transcribe the viral latent genes. The tumor cells are of endothelial lineage and exhibit the same molecular pattern of pathway activation as KS, namely phosphatidylinositol 3-kinase (PI3K)/Akt/mTOR, interleukin-10 (IL-10), and vascular endothelial growth factor (VEGF). The KSHV-induced tumors are more aggressive than Ha-ras-induced angiosarcomas. Overall survival is increased by prophylactic ganciclovir. Thus, whole-virus KSHV-transgenic mice represent an accurate model for KS and open the door for the genetic dissection of KS pathogenesis and evaluation of therapies, including vaccines.

Clinical Significance of Elevated KSHV Viral Load in HIV-Related Kaposi's Sarcoma Patients in South Africa

Kaposi's sarcoma (KS) is an AIDS-defining illness caused by Kaposi's sarcoma-associated herpesvirus (KSHV) predominantly in the context of HIV-related immune suppression. We aimed to explore the usefulness of KSHV DNA viral load (VL) measurement in predicting the severity, response to treatment and outcome of KS. We retrospectively assessed a cohort of KS patients (n = 94) receiving treatment at Groote Schuur Hospital, Cape Town, South Africa. Demographic and clinical data, KS staging and response to treatment were extracted from patient files, while long-term survival was ascertained from hospital records. KSHV serology and VL and hIL-6 were determined empirically from patients' blood. All patients were HIV-positive adults, the majority of whom were on HAART at the time of recruitment. KSHV VL was detectable in 65 patients' blood (median: 280.5/106 cells (IQR: 69.7-1727.3)) and was highest in patients with S1 HIV-related systemic disease (median 1066.9/106 cells, IQR: 70.5-11,269.6). KSHV VL was associated with the S1 stage in a binomial regression controlling for confounders (adjusted odds ratio 5.55, 95% CI: 1.28-24.14, p = 0.022). A subset of six patients identified to have extremely high KSHV VLs was predominantly T1 stage with pulmonary KS, and most had died at follow-up. In our cohort, elevated KSHV VL is associated with systemic HIV-related illness in KS disease. Extremely high KSHV VLs warrant further investigation for patients potentially requiring intensive treatment and investigation for progression or diagnosis of concurrent KSHV lytic syndromes.

Hypoxia and hypoxia-inducible factors in Kaposi sarcoma-associated herpesvirus infection and disease pathogenesis

Kaposi sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi sarcoma and several other tumors and hyperproliferative diseases seen predominantly in human immunodeficiency virus-infected and other immunocompromised persons. There is an increasing body of evidence showing that hypoxia and hypoxia-inducible factors (HIFs) play important roles in the biology of KSHV and in the pathogenesis of KSHV-induced diseases. Hypoxia and HIFs can induce lytic activation of KSHV and KSHV can in turn lead to a hypoxic-like state in infected cells. In this review, we describe the complex interactions between KSHV biology, the cellular responses to hypoxia, and the pathogenesis of KSHV-induced diseases. We also describe how interference with HIFs can lead to decreased tumor growth and/or death of infected cells and KSHV-induced tumors. Finally, we show how these observations may lead to novel strategies for the treatment of KSHV-induced diseases.

A Challenging Case of Kaposi Sarcoma Inflammatory Cytokine Syndrome

Kaposi Sarcoma Inflammatory Cytokine Syndrome (KICS) is a serious, uncommon disease that occurs in patients who are positive for HIV and human herpesvirus-8 (HHV-8). It is characterized by a constellation of clinical findings, including fever, weight loss, and fluid retention, as well as a lack of multicentric Castleman disease (MCD) features on histopathology and an elevated serum HHV-8 viral load. Diagnosis is often delayed, and treatment options are limited, culminating in high mortality rates. We hereby present a 32-year-old male patient with HIV who was untreated for a few years and came with fever, night sweats, pancytopenia, and widespread adenopathy. A thorough evaluation of opportunistic infections was unremarkable. Clinically MCD was suspected, but lymph node biopsy only showed Kaposi sarcoma (KS) with no characteristic features of MCD. However, with clinical deterioration, KICS was strongly suspected. Kaposi sarcoma immune reconstitution syndrome (KS-IRIS) was also a possibility as the patient was restarted on antiretroviral therapy. Rituximab was commenced, but the patient suffered a cardiac arrest and could not be revived. Alternative diagnosis must be explored in patients with HIV presenting with constitutional symptoms, cytopenia, and adenopathy after opportunistic infections and malignancies are ruled out. If they have KS with HHV-8 positivity and there is a lack of characteristic features of MCD in lymph node biopsy, prompt suspicion of KICS should be made, and treatment with rituximab and/or chemotherapy should be instituted rapidly. KS-IRIS is also possible if patients have recently received antiretroviral therapy and have a rapid decline in viral load and increase in CD4 counts (immunological recovery). HHV8 viral load levels may help to distinguish between these two inflammatory conditions.

Clinical management of Kaposi sarcoma herpesvirus-associated diseases: an update on disease manifestations and treatment strategies

INTRODUCTION

Kaposi sarcoma herpes virus (KSHV) is associated with several diseases including Kaposi sarcoma, a form of multicentric Castleman's disease, primary effusion lymphoma, and an inflammatory cytokine syndrome. These KSHV-associated diseases (KAD) can present with heterogenous signs and symptoms that are often associated with cytokine dysregulation that may result in multiorgan dysfunction. The inability to promptly diagnose and treat these conditions can result in long-term complications and mortality.

AREAS COVERED

Existing epidemiological subtypes of existing KSHV-associated diseases, specifically Kaposi sarcoma as well as the incidence of several KSHV-associated disorders are described. We review the KSHV latent and lytic phases as they correlate with KSHV-associated diseases. Given the complicated presentations, we discuss the clinical manifestations, current diagnostic criteria, existing treatment algorithms for individual KAD, and when they occur concurrently. With emerging evidence on the virus and host interactions, we evaluate novel approaches for the treatment of KAD. An extensive literature search was conducted to support these findings.

EXPERT OPINION

KSHV leads to complex and concurrent disease processes that are often underdiagnosed both in the United States and worldwide. New therapies that exist for many of these conditions focus on chemotherapy-sparing options that seek to target the underlying viral pathogenesis or immunotherapy strategies.

High Seroprevalence of Kaposi Sarcoma-Associated Herpesvirus in Men Who Have Sex With Men With HIV in the Southern United States

Background

Disparities in mortality in human immunodeficiency virus (HIV)-associated Kaposi sarcoma have been described, particularly in Black men in the southern United States. It is unclear if there are racial/ethnic differences in the seroprevalence of Kaposi sarcoma-associated herpesvirus (KSHV) that may be contributing.

Methods

This is a cross-sectional study of men who have sex with men (MSM) and transgender women with HIV. Participants were recruited from an outpatient HIV clinic in Dallas, Texas, for a 1-time study visit and were excluded from analysis if they had any history of KSHV disease. Plasma was tested for antibodies to KSHV K8.1 or ORF73 antigens, and KSHV DNA was measured in oral fluids and blood by polymerase chain reaction. KSHV seroprevalence and viral shedding in blood and oral fluids were calculated. Additionally, independent risk factors for KSHV seropositivity were assessed by multivariable logistic regression analysis.

Results

Two hundred five participants were included in our analysis. Overall, KSHV seroprevalence was high (68%) with no significant difference between racial/ethnic groups. Among seropositive participants, KSHV DNA was detected in 28.6% of oral fluids and 10.9% of peripheral blood specimens, respectively. The factors most strongly associated with KSHV seropositivity were oral-anal sex (odds ratio [OR], 3.02), oral-penile sex (OR, 4.63), and methamphetamine use (OR, 4.67).

Conclusions

High local seroprevalence of KSHV is likely a key driver of the high burden of KSHV-associated diseases regionally, though it does not explain the observed disparities in KSHV-associated disease prevalence among racial/ethnic groups. Our findings support that KSHV is primarily transmitted via exchange of oral fluids.

KSHV Viral Protein Kinase Interacts with USP9X to Modulate the Viral Lifecycle

Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi sarcoma (KS), the plasmablastic form of multicentric Castleman's disease, and primary effusion lymphoma. In sub-Saharan Africa, KS is the most common HIV-related malignancy and one of the most common childhood cancers. Immunosuppressed patients, including HIV-infected patients, are more prone to KSHV-associated disease. KSHV encodes a viral protein kinase (vPK) that is expressed from ORF36. KSHV vPK contributes to the optimal production of infectious viral progeny and upregulation of protein synthesis. To elucidate the interactions of vPK with cellular proteins in KSHV-infected cells, we used a bottom-up proteomics approach and identified host protein ubiquitin-specific peptidase 9X-linked (USP9X) as a potential interactor of vPK. Subsequently, we validated this interaction using a co-immunoprecipitation assay. We report that both the ubiquitin-like and the catalytic domains of USP9X are important for association with vPK. To uncover the biological relevance of the USP9X/vPK interaction, we investigated whether the knockdown of USP9X would modulate viral reactivation. Our data suggest that depletion of USP9X inhibits both viral reactivation and the production of infectious virions. Understanding how USP9X influences the reactivation of KSHV will provide insights into how cellular deubiquitinases regulate viral kinase activity and how viruses co-opt cellular deubiquitinases to propagate infection. Hence, characterizing the roles of USP9X and vPK during KSHV infection constitutes a first step toward identifying a potentially critical interaction that could be targeted by future therapeutics. IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi sarcoma (KS), the plasmablastic form of multicentric Castleman's disease, and primary effusion lymphoma. In sub-Saharan Africa, KS is the most common HIV-related malignancy. KSHV encodes a viral protein kinase (vPK) that aids viral replication. To elucidate the interactions of vPK with cellular proteins in KSHV-infected cells, we used an affinity purification approach and identified host protein ubiquitin-specific peptidase 9X-linked (USP9X) as a potential interactor of vPK. Depletion of USP9X inhibits both viral reactivation and the production of infectious virions. Overall, our data suggest a proviral role for USP9X.

Approche thérapeutique des maladies de Castleman : l’émergence des thérapies ciblées

The spectrum of Castleman disease encompasses several different disorders. Nowadays three different forms of the disease are individualized: unicentric Castleman disease, multicentric HHV-8 associated Castleman disease and idiopathic multicentric Castleman disease. In the latter a severe form called TAFRO syndrome (thrombocytopenia, anasarca, myelofibrosis, renal dysfunction, and organomegaly) tend to be individualized. Improvement in the classification and understanding of the physiopathology of CD have allowed improvement in treatment strategies. Treatment of rare but often severe manifestations, such as paraneoplastic pemphigus and bronchiolitis obliterans in unicentric CD and hemophagocytic syndrome and/or Kaposi' sarcoma in HHV8 associated CD, are better adapted. Most of current treatment strategies are based on retrospective and very few prospective studies. Both anti-IL6/6R and anti-CD20 biotherapies have greatly improved the management of certain forms of the disease. We report in this review the most relevant studies and national or international expert consensus statements for the treatment in the different types of CD. © 2022 Published by Elsevier Masson SAS on behalf of Société nationale française de médecine interne (SNFMI).

Cancers associated with human gammaherpesviruses

Epstein-Barr virus (EBV; human herpesvirus 4; HHV-4) and Kaposi sarcoma-associated herpesvirus (KSHV; human herpesvirus 8; HHV-8) are human gammaherpesviruses that have oncogenic properties. EBV is a lymphocryptovirus, whereas HHV-8/KSHV is a rhadinovirus. As lymphotropic viruses, EBV and KSHV are associated with several lymphoproliferative diseases or plasmacytic/plasmablastic neoplasms. Interestingly, these viruses can also infect epithelial cells causing carcinomas and, in the case of KSHV, endothelial cells, causing sarcoma. EBV is associated with Burkitt lymphoma, classic Hodgkin lymphoma, nasopharyngeal carcinoma, plasmablastic lymphoma, lymphomatoid granulomatosis, leiomyosarcoma, and subsets of diffuse large B-cell lymphoma, post-transplant lymphoproliferative disorder, and gastric carcinoma. KSHV is implicated in Kaposi sarcoma, primary effusion lymphoma, multicentric Castleman disease, and KSHV-positive diffuse large B-cell lymphoma. Pathogenesis by these two herpesviruses is intrinsically linked to viral proteins expressed during the lytic and latent lifecycles. This comprehensive review intends to provide an overview of the EBV and KSHV viral cycles, viral proteins that contribute to oncogenesis, and the current understanding of the pathogenesis and clinicopathology of their related neoplastic entities.

Mechanism of herpesvirus protein kinase UL13 in immune escape and viral replication

Upon infection, the herpes viruses create a cellular environment suitable for survival, but innate immunity plays a vital role in cellular resistance to viral infection. The UL13 protein of herpesviruses is conserved among all herpesviruses and is a serine/threonine protein kinase, which plays a vital role in escaping innate immunity and promoting viral replication. On the one hand, it can target various immune signaling pathways in vivo, such as the cGAS-STING pathway and the NF-κB pathway. On the other hand, it phosphorylates regulatory many cellular and viral proteins for promoting the lytic cycle. This paper reviews the research progress of the conserved herpesvirus protein kinase UL13 in immune escape and viral replication to provide a basis for elucidating the pathogenic mechanism of herpesviruses, as well as providing insights into the potential means of immune escape and viral replication of other herpesviruses that have not yet resolved the function of it.

The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Lymphoid Neoplasms

We herein present an overview of the upcoming 5^th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the revised 4^th edition. These include reorganization of entities by a hierarchical system as is adopted throughout the 5^th edition of the WHO classification of tumours of all organ systems, modification of nomenclature for some entities, revision of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities, as well as inclusion of tumour-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms.

Efficacy and Safety of Regimens Used for the Treatment of Multicentric Castleman Disease: A Systematic Review

OBJECTIVES

Treatment options for multicentric Castleman disease (MCD) remain limited. The only FDA-approved drug is siltuximab for idiopathic MCD (iMCD), but the response rate with siltuximab is less than 50%. We performed a systematic review to examine the efficacy and safety of various regimens used for the treatment of MCD.

METHODS

A database search on PubMed, Embase, Cochrane, Web of Science, and Clinicaltrials.gov using the terms "Castleman disease," "treatment outcome" and "patient safety" was done.

RESULTS AND CONCLUSIONS

Results from a randomized controlled trial (RCT) and an extension study highlighted the efficacy and long-term safety of siltuximab for iMCD; other trials showed tocilizumab to be a suitable alternative. A recent trial reported high response rates with thalidomide in iMCD patients. Promising results were reported for bortezomib in relapsed/ refractory MCD. For human herpesvirus 8 (HHV-8) associated MCD, rituximab along with doxorubicin therapy followed by maintenance with zidovudine and valganciclovir is the most effective therapy. A single-arm trial has highlighted the potential role of tocilizumab in HHV-8 MCD. Data for these regimens are limited and mostly comprise non-randomized trials. Further research on emerging agents could have a major impact on the treatment of this rare disease.

KSHV/HHV8-mediated hematologic diseases

Kaposi sarcoma (KS) herpesvirus (KSHV), also known as human herpesvirus 8, is the causal agent of KS but is also pathogenetically related to several lymphoproliferative disorders, including primary effusion lymphoma (PEL)/extracavitary (EC) PEL, KSHV-associated multicentric Castleman disease (MCD), KSHV+ diffuse large B-cell lymphoma, and germinotropic lymphoproliferative disorder. These different KSHV-associated diseases may co-occur and may have overlapping features. KSHV, similar to Epstein-Barr virus (EBV), is a lymphotropic gammaherpesvirus that is preferentially present in abnormal lymphoid proliferations occurring in immunecompromised individuals. Notably, both KSHV and EBV can infect and transform the same B cell, which is frequently seen in KSHV+ EBV+ PEL/EC-PEL. The mechanisms by which KSHV leads to lymphoproliferative disorders is thought to be related to the expression of a few transforming viral genes that can affect cellular proliferation and survival. There are critical differences between KSHV-MCD and PEL/EC-PEL, the 2 most common KSHV-associated lymphoid proliferations, including viral associations, patterns of viral gene expression, and cellular differentiation stage reflected by the phenotype and genotype of the infected abnormal B cells. Advances in treatment have improved outcomes, but mortality rates remain high. Our deepening understanding of KSHV biology, clinical features of KSHV-associated diseases, and newer clinical interventions should lead to improved and increasingly targeted therapeutic interventions.

Therapeutic Perspectives in the Systemic Treatment of Kaposi's Sarcoma

In patients with Kaposi's sarcoma (KS), the therapeutic goal is to achieve a durable remission in the size and number of skin and visceral lesions. Although most patients show tumor regression in response to standard systemic chemotherapy regimens, alternative systemic treatments are needed for patients who develop refractory KS. Anti-angiogenic therapies represent attractive therapeutic targets in this context, due to the central role of angiogenesis in KS pathogenesis. Pomalidomide, which exhibits such anti-angiogenic activity through inhibition of VEGF, currently constitutes the most promising agent of this class and has been recently approved by the FDA. In addition, immune checkpoint blockade also represents an interesting alternative therapeutic approach through the restoration of immunity against HHV-8, the causative agent of KS, and improvement of tumor control. Although small series of cases treated successfully with these drugs have been reported, there is no marketing approval for anti-immune checkpoint antibodies for KS to date. In the present review, we will discuss potential therapeutic options for patients with recurrent or refractory KS, including systemic chemotherapies, immune checkpoint inhibitors, anti-herpesvirus agents, and anti-angiogenic drugs. Well-conducted clinical trials in this population are urgently needed to correctly address the efficacy of targeted agents and immunomodulators, while monitoring for adverse effects.

[HHV-8 Related immunological and hematological diseases]

HHV-8 is an oncogenic Gammaherpesvirinae discovered in 1994 during the HIV pandemic. It is the causative agent of Kaposi's sarcoma, and is also associated with the occurrence of several aggressive B lymphoproliferative disorders. Most of them occur in an immunosuppression setting, usually due to HIV infection. Multicentric HHV8-associated Castleman's disease and KSHV Inflammatory Cytokine Syndrome (KICS) are primarily reactive entities with prominent systemic features. They illustrate the cytokinic storm induced by HHV-8 in its cell host. On the other hand, HHV-8 can drive proliferation and lymphomagenesis of its plasmablastic cell host, and is associated with a risk to develop aggressive lymphomas with plasmacytic differenciation. Primary effusion lymphoma usually localizes in body cavities and may affect other extra-nodal sites ; its prognostic is poor. Diffuse large B-cell lymphoma HHV-8, NOS affect more commonly nodes and blood and evolve from infected cell of HHV-8 associated Castleman disease. On the contrary, germinotropic lymphoproliferative disorders presents mainly as localized adenopathy with indolent course, and show polyclonality. Histology plays a key role in distinguishing these different entities and need expert reviewing, especially since they may be associated with each other. Besides lymphoproliferative disorders, HHV8 is associated with various hematological manifestations. The aim of this review is to provide an update on the presentation, diagnosis, and management of immunologic and hematologic complications associated with HHV-8.

Castleman disease

Castleman disease (CD), a heterogeneous group of disorders that share morphological features, is divided into unicentric CD and multicentric CD (MCD) according to the clinical presentation and disease course. Unicentric CD involves a solitary enlarged lymph node and mild symptoms and excision surgery is often curative. MCD includes a form associated with Kaposi sarcoma herpesvirus (KSHV) (also known as human herpesvirus 8) and a KSHV-negative idiopathic form (iMCD). iMCD can present in association with severe syndromes such as TAFRO (thrombocytopenia, ascites, fever, reticulin fibrosis and organomegaly) or POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder and skin changes). KSHV-MCD often occurs in the setting of HIV infection or another cause of immune deficiency. The interplay between KSHV and HIV elevates the risk for the development of KSHV-induced disorders, including KSHV-MCD, KSHV-lymphoproliferation, KSHV inflammatory cytokine syndrome, primary effusion lymphoma and Kaposi sarcoma. A CD diagnosis requires a multidimensional approach, including clinical presentation and imaging, pathological features, and molecular virology. B cell-directed monoclonal antibody therapy is the standard of care in KSHV-MCD, and anti-IL-6 therapy is the recommended first-line therapy and only treatment of iMCD approved by the US FDA and EMA.

KSHV/HHV8-Associated Lymphoproliferative Disorders: Lessons Learnt from People Living with HIV

In 1992, Kaposi sarcoma herpesvirus (KSHV/HHV8) was discovered and identified as the causative agent for Kaposi sarcoma. Subsequently, the presence of this virus has been detected in a number of lymphoproliferative disorders in people living with HIV (PLWH), including: KSHV-associated multicentric Castleman disease, primary effusion lymphoma, KSHV-positive diffuse large B-cell lymphoma, and germinotropic lymphoproliferative disorder. Each of these rare entities has subsequently been diagnosed in HIV-negative individuals. The recognition of some of these KSHV/HHV8-associated lymphoproliferative disorders has led to their inclusion in the WHO classification of lymphomas in 2008 and the revision of 2016; however, further revision is under way to update the classification. The relatively recent recognition of these lymphoproliferative disorders and their low incidence, particularly in the HIV-negative population, means that there is little published evidence and consensus on their clinical features and management. The publication of a new WHO classification of lymphomas should yield diagnostic clarity, providing an impetus for retrospective case series and prospective clinical trials in these KSHV/HHV8-associated lymphoproliferative disorders.

Recent Advances in Developing Treatments of Kaposi's Sarcoma Herpesvirus-Related Diseases

Kaposi-sarcoma-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV-8) is the causative agent of several malignancies, including Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD). Active KSHV replication has also been associated with a pathological condition called KSHV inflammatory cytokine syndrome (KICS), and KSHV may play a role in rare cases of post-transplant polyclonal lymphoproliferative disorders. Several commonly used herpesviral DNA polymerase inhibitors are active against KSHV in tissue culture. Unfortunately, they are not always efficacious against KSHV-induced diseases. To improve the outcome for the patients, new therapeutics need to be developed, including treatment strategies that target either viral proteins or cellular pathways involved in tumor growth and/or supporting the viral life cycle. In this review, we summarize the most commonly established treatments against KSHV-related diseases and review recent developments and promising new compounds that are currently under investigation or on the way to clinical use.

Multicentric Castleman's disease in HIV patients: a single-center cohort diagnosed from 2008 to 2018

Purpose

Castleman’s disease (CD) is a well-established entity but there is a lack of available data regarding the management and therapy of HIV- and HHV-8-positive multicentric CD (MCD). We provide our own single-center experience with HIV-associated MCD.

Methods

We performed a retrospective, descriptive study on a cohort of patients with MCD, diagnosed and admitted to the infectious diseases or intensive care unit in the University Hospital Düsseldorf between 2008 and 2018. Included patients had a previous or new HIV diagnosis and clinical signs resembling MCD with evidence of HHV-8 replication or histological diagnosis for MCD.

Results

Nine male patients were included in the study. All patients were treated with Rituximab after diagnosis of MCD, with six of them acquiring resolution of symptoms. Three patients received tocilizumab additionally. Other treatment options included: splenectomy (2/9), valganciclovir (2/9), vincristine and siltuximab (1/9), ruxolitinib and Cytosorb^® (2/9). The relapse rate was 44% (4/9) and the survival rate 87.5% after 1 year (8/9) and 71.4% after 3 years (5/7).

Conclusion

The most effective first-line therapy and retreatment option remains rituximab. The effectiveness of other treatment options like splenectomy or different immunotherapeutic approaches requires confirmation in larger-scale studies.

Characteristics and outcomes of KSHV-associated multicentric Castleman disease with or without other KSHV diseases

Kaposi sarcoma (KS)-associated herpesvirus (KSHV)-associated multicentric Castleman disease (MCD) is a relapsing and remitting systemic lymphoproliferative disorder characterized by severe inflammatory symptoms most common among people living with HIV (PLWH). Patients with KSHV-MCD may present with concurrent KSHV-associated diseases, such as KS and/or primary effusion lymphoma (PEL). We evaluated clinical and immunologic characteristics, the effects of concurrent KSHV malignancies, and treatments from the largest prospective natural history study of participants with KSHV-MCD within the United States. Treatment options administered at investigator discretion included high-dose zidovudine with valganciclovir (AZT/VGC), rituximab, or rituximab with liposomal doxorubicin (R-Dox) during KSHV-MCD flares. Survival analyses and prognostic factors were explored for all participants. Sixty-two participants with HIV were enrolled, including 20 with KSHV-MCD alone, 34 with KSHV-MCD and KS, 1 with KSHV-MCD and PEL, and 7 with all KSHV-associated diseases. Forty-four percent of KSHV-MCD diagnoses were made at our institution. Forty-four participants received rituximab-based therapies, 20 of whom had maintenance AZT/VGC or interferon. Participants receiving R-Dox and then maintenance AZT/VGC had the highest 5-year progression-free survival (89%). Cytokine profiles during KSHV-MCD flares did not differ by the presence of concurrent KSHV-associated diseases. The 10-year survival was 71% (95% confidence interval [CI], 56% to 82%) for all participants. A concurrent diagnosis of PEL negatively impacted survival (PEL hazard ratio, 5.4; 95% CI, 1.8 to 16.8). KSHV-MCD is an underdiagnosed condition among PLWH, including those with KS. KSHV-MCD has an excellent prognosis with appropriate treatment. Physicians should be alert for patients with multiple KSHV diseases, which impact optimal treatment and survival outcomes. This study was registered at www.clinicaltrials.gov as #NCT00099073.

Chapter XX Antiviral Treatment and Cancer Control

Hepatitis B virus (HBV), hepatitis C virus (HCV), human papilloma virus (HPV), Epstein-Barr virus (EBV), human T-cell lymphotropic virus type 1 (HTLV-1), Kaposi's sarcoma-associated herpesvirus (KSHV), and Merkel cell polyomavirus (MCV) contribute to about 10-15% global burden of human cancers. Conventional chemotherapy or molecular target therapies have been used to treat virus-associated cancers. However, a more proactive approach would be the use of antiviral treatment to suppress or eliminate viral infections to prevent the occurrence of cancer in the first place. Antiviral treatments against chronic HBV and HCV infection have achieved this goal, with significant reduction in the incidence of hepatocellular carcinoma in treated patients. Antiviral treatments for EBV, KSHV, and HTLV-1 had limited success in treating refractory EBV-associated lymphoma and post-transplant lymphoproliferative disorder, KSHV-associated Kaposi's sarcoma in AIDS patients, and HTLV-1-associated acute, chronic, and smoldering subtypes of adult T-cell lymphoma, respectively. Therapeutic HPV vaccine and RNA interference-based therapies for treating HPV-associated infection or cervical cancers also showed some encouraging results. Taken together, antiviral therapies have yielded promising results in cancer prevention and treatment. More large-scale studies in a real-world setting are necessary to confirm the efficacy of antiviral therapy. Further investigation for more effective and convenient antiviral regimens warrants more attention.

Proteomic approaches to investigate gammaherpesvirus biology and associated tumorigenesis

The DNA viruses, Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are members of the gammaherpesvirus subfamily, a group of viruses whose infection is associated with multiple malignancies, including cancer. The primary host for these viruses is humans and, like all herpesviruses, infection with these pathogens is lifelong. Due to the persistence of gammaherpesvirus infection and the potential for cancer formation in infected individuals, there is a driving need to understand not only the biology of these viruses and how they remain undetected in host cells but also the mechanism(s) by which tumorigenesis occurs. One of the methods that has provided much insight into these processes is proteomics. Proteomics is the study of all the proteins that are encoded by a genome and allows for (i) identification of existing and novel proteins derived from a given genome, (ii) interrogation of protein-protein interactions within a system, and (iii) discovery of druggable targets for the treatment of malignancies. In this chapter, we explore how proteomics has contributed to our current understanding of gammaherpesvirus biology and their oncogenic processes, as well as the clinical applications of proteomics for the detection and treatment of gammaherpesvirus-associated cancers.

Overview of Castleman disease

Castleman disease (CD) describes a group of at least 4 disorders that share a spectrum of characteristic histopathological features but have a wide range of etiologies, presentations, treatments, and outcomes. CD includes unicentric CD (UCD) and multicentric CD (MCD), the latter of which is divided into idiopathic MCD (iMCD), human herpes virus-8 (HHV8)-associated MCD (HHV8-MCD), and polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, skin changes (POEMS)-associated MCD (POEMS-MCD). iMCD can be further subclassified into iMCD-thrombocytopenia, ascites, reticulin fibrosis, renal dysfunction, organomegaly (iMCD-TAFRO) or iMCD-not otherwise specified (iMCD-NOS). Advances in diagnosis, classification, pathogenesis, and therapy are substantial since the original description of UCD by Benjamin Castleman in 1954. The advent of effective retroviral therapy and use of rituximab in HHV8-MCD have improved outcomes in HHV8-MCD. Anti-interleukin-6-directed therapies are highly effective in many iMCD patients, but additional therapies are required for refractory cases. Much of the recent progress has been coordinated by the Castleman Disease Collaborative Network (CDCN), and further progress will be made by continued engagement of physicians, scientists, and patients. Progress can also be facilitated by encouraging patients to self-enroll in the CDCN's ACCELERATE natural history registry (#NCT02817997; www.CDCN.org/ACCELERATE).

Dual infection and recombination of Kaposi sarcoma herpesvirus revealed by whole-genome sequence analysis of effusion samples

Kaposi sarcoma herpesvirus (KSHV) is the etiological agent of three malignancies, Kaposi sarcoma (KS), primary effusion lymphoma (PEL) and KSHV-associated multicentric Castelman disease. KSHV infected patients may also have an interleukin six-related KSHV-associated inflammatory cytokine syndrome. KSHV-associated diseases occur in only a minority of chronically KSHV-infected individuals and often in the setting of immunosuppression. Mechanisms by which KSHV genomic variations and systemic co-infections may affect the pathogenic pathways potentially leading to these diseases have not been well characterized in vivo. To date, the majority of comparative genetic analyses of KSHV have been focused on a few regions scattered across the viral genome. We used next-generation sequencing techniques to investigate the taxonomic groupings of viruses from malignant effusion samples from fourteen participants with advanced KSHV-related malignancies, including twelve with PEL and two with KS and elevated KSHV viral load in effusions. The genomic diversity and evolutionary characteristics of nine isolated, near full-length KSHV genomes revealed extensive evidence of mosaic patterns across all these genomes. Further, our comprehensive NGS analysis allowed the identification of two distinct KSHV genome sequences in one individual, consistent with a dual infection. Overall, our results provide significant evidence for the contribution of KSHV phylogenomics to the origin of KSHV subtypes. This report points to a wider scope of studies to establish genome-wide patterns of sequence diversity and define the possible pathogenic role of sequence variations in KSHV-infected individuals.

A Rare Case of the Newly Recognized Kaposi Sarcoma Herpesvirus-Associated Disease

Kaposi sarcoma herpesvirus (KSHV) is associated with Kaposi sarcoma (KS), primary effusion lymphoma, and multicentric Castleman disease (KSHV-MCD) in patients infected with human immunodeficiency virus (HIV). We present a case consistent with a newly recognized KSHV inflammatory cytokine syndrome (KICS), distinct from KSHV-MCD. Although both disorders exhibit signs of substantial inflammation, KICS has minimal lymphadenopathy/splenomegaly and negative pathologic nodal changes in the setting of low CD4 count. KICS is easily misdiagnosed as severe sepsis or other KS-related diseases in HIV/AIDS patients and carries a high mortality. ​Standard therapy is still under investigation due to its rarity, whereas the treatment regimen for KSHV-MCD may lead to clinical remission. Early recognition and prompt management are crucial to improve the survival of the under-recognized KICS.

The Anti-Angiogenic Effects of Anti-Human Immunodeficiency Virus Drugs

The growth and metastasis of malignant tumors benefit from the formation of blood vessels within the tumor area. There, new vessels originate from angiogenesis (the sprouting of pre-existing neighboring vessels) and/or vasculogenesis (the mobilization of bone marrow-derived endothelial cell precursors which incorporate in tumor vasculature and then differentiate into mature endothelial cells). These events are induced by soluble molecules (the angiogenic factors) and modulated by endothelial cell interactions with the perivascular matrix. Given angiogenesis/vasculogenesis relevance to tumor progression, anti-angiogenic drugs are often employed to buttress surgery, chemotherapy or radiation therapy in the treatment of a wide variety of cancers. Most of the anti-angiogenic drugs have been developed to functionally impair the angiogenic vascular endothelial growth factor: however, this leaves other angiogenic factors unaffected, hence leading to drug resistance and escape. Other anti-angiogenic strategies have exploited classical inhibitors of enzymes remodeling the perivascular matrix. Disappointingly, these inhibitors have been found toxic and/or ineffective in clinical trials, even though they block angiogenesis in pre-clinical models. These findings are stimulating the identification of other anti-angiogenic compounds. In this regard, it is noteworthy that drugs utilized for a long time to counteract human immune deficiency virus (HIV) can directly and effectively hamper molecular pathways leading to blood vessel formation. In this review the mechanisms leading to angiogenesis and vasculogenesis, and their susceptibility to anti-HIV drugs will be discussed.

The Potential Clinical Benefit of Tocilizumab Therapy for Patients with HHV-8-infected AIDS-related Multicentric Castleman Disease: A Case Report and Literature Review

Castleman disease (CD), also known as angiofollicular hyperplasia, is a rare disorder characterized by nonmalignant mediastinal lymph node enlargement provoked by excess interleukin-6 (IL-6) secretion. It could be unicentric or multicentric (MCD). Here, we describe a 27-year-old man with a prior history of AIDS, Kaposi sarcoma (KS), and latent syphilis who presented to the ED for persistent fatigue, fever, chills, night sweats, and productive cough. Infectious workup was negative, and the patient continued to have a high fever despite empiric antibiotic therapy. Bone marrow biopsy was performed and was negative for malignancy. The patient eventually underwent a left clavicular lymph node biopsy, which showed a plasma cell variant CD with positive immunostaining for human herpesvirus 8 (HHV-8), and high HHV-8 viral load. We started the patient on rituximab and liposomal doxorubicin, but unfortunately, the patient had a severe anaphylactic reaction to the rituximab, so we could not proceed with this treatment. We, therefore, started tocilizumab treatment, which improved the patient's general condition, and he was eventually discharged from our hospital. Upon follow-up 11-months later, a repeat CT scan of the chest and abdomen showed a near-complete treatment response with decreased lymphadenopathy throughout and hepatosplenomegaly. IL-6 overproduction in patients with CD is linked to the production of inflammatory cytokines and has a role in tumor angiogenesis, which makes it potential for IL-6 targeted therapy. The diagnosis of CD, especially MCD, requires a high index of suspicion, and a lymph node biopsy is essential in the diagnosis. Tocilizumab, an IL-6 receptor antibody, could potentially be considered as a practical therapeutic approach in managing HHV-8 positive MCD patients who do not tolerate or respond to initial rituximab therapy.

Induction of Kaposi's Sarcoma-Associated Herpesvirus-Encoded Thymidine Kinase (ORF21) by X-Box Binding Protein 1

Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent for Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman disease (MCD). Like other herpesviruses, it has latent and lytic repertoires. However, there is evidence that some lytic genes can be directly activated by certain cellular factors. Cells undergoing endoplasmic reticulum stress express spliced X-box binding protein 1 (XBP-1s). XBP-1s is also present in large amounts in germinal center B cells. XBP-1s can activate the KSHV replication and transcription activator (RTA) and lytic replication. It can also directly activate KSHV-encoded viral interleukin-6 (vIL-6) and, thus, contribute to the pathogenesis of KSHV MCD. KSHV thymidine kinase (TK), the ORF21 gene product, can enhance the production of dTTP and is important for lytic replication. It can also phosphorylate zidovudine and ganciclovir to toxic moieties, enabling treatment of KSHV-MCD with these drugs. We show here that XBP-1s can directly activate ORF21 and that this activation is mediated primarily through two XBP-response elements (XRE) on the ORF21 promoter region. Deletion or mutation of these elements eliminated XBP-1s-induced upregulation of the promoter, and chromatin immunoprecipitation studies provide evidence that XBP-1s can bind to both XREs. Exposure of PEL cells to a chemical inducer of XBP-1s can induce ORF21 within 4 hours, and ORF21 expression in the lymph nodes of patients with KSHV-MCD is predominantly found in cells with XBP-1. Thus, XBP-1s may directly upregulate KSHV ORF21 and, thus, contribute to the pathogenesis of KSHV-MCD and the activity of zidovudine and valganciclovir in this disease.IMPORTANCE Spliced X-box binding protein 1 (XBP-1s), part of the unfolded protein response and expressed in developing germinal center B cells, can induce Kaposi's sarcoma-associated herpesvirus (KSHV) lytic replication and directly activate viral interleukin-6 (vIL-6). We show here that XBP-1s can also directly activate KSHV ORF21, a lytic gene. ORF21 encodes KSHV thymidine kinase (TK), which increases the pool of dTTP for viral replication and enhances lytic replication. Direct activation of ORF21 by XBP-1s can enhance viral replication in germinal center B cells and contribute to the pathogenesis of KSHV multicentric Castleman disease (MCD). KSHV-MCD is characterized by systemic inflammation caused, in part, by lytic replication and overproduction of KSHV vIL-6 in XBP-1s-expressing lymph node plasmablasts. KSHV thymidine kinase can phosphorylate zidovudine and ganciclovir to toxic moieties, and direct activation of ORF21 by XBP-1s may also help explain the effectiveness of zidovudine and valganciclovir in the treatment of KSHV-MCD.

Targeting Kaposi's Sarcoma-Associated Herpesvirus ORF21 Tyrosine Kinase and Viral Lytic Reactivation by Tyrosine Kinase Inhibitors Approved for Clinical Use

Kaposi's sarcoma-associated herpesvirus (KSHV) is the cause of three human malignancies: Kaposi's sarcoma, primary effusion lymphoma, and the plasma cell variant of multicentric Castleman disease. Previous research has shown that several cellular tyrosine kinases play crucial roles during several steps in the virus replication cycle. Two KSHV proteins also have protein kinase function: open reading frame (ORF) 36 encodes a serine-threonine kinase, while ORF21 encodes a thymidine kinase (TK), which has recently been found to be an efficient tyrosine kinase. In this study, we explore the role of the ORF21 tyrosine kinase function in KSHV lytic replication. By generating a recombinant KSHV mutant with an enzymatically inactive ORF21 protein, we show that the tyrosine kinase function of ORF21/TK is not required for the progression of the lytic replication in tissue culture but that it is essential for the phosphorylation and activation to toxic moieties of the antiviral drugs zidovudine and brivudine. In addition, we identify several tyrosine kinase inhibitors, already in clinical use against human malignancies, which potently inhibit not only ORF21 TK kinase function but also viral lytic reactivation and the development of KSHV-infected endothelial tumors in mice. Since they target both cellular tyrosine kinases and a viral kinase, some of these compounds might find a use in the treatment of KSHV-associated malignancies.IMPORTANCE Our findings address the role of KSHV ORF21 as a tyrosine kinase during lytic replication and the activation of prodrugs in KSHV-infected cells. We also show the potential of selected clinically approved tyrosine kinase inhibitors to inhibit KSHV TK, KSHV lytic replication, infectious virion release, and the development of an endothelial tumor. Since they target both cellular tyrosine kinases supporting productive viral replication and a viral kinase, these drugs, which are already approved for clinical use, may be suitable for repurposing for the treatment of KSHV-related tumors in AIDS patients or transplant recipients.

Runaway Kaposi Sarcoma-associated herpesvirus replication correlates with systemic IL-10 levels

KSHV-associated inflammatory cytokine syndrome (KICS) is caused by Kaposi's sarcoma-associated herpesvirus (KSHV). KICS is associated with high-level, systemic replication of KSHV. This study characterized the clinical and virologic features of a KICS patient over time. Additionally, it compared the cytokine profiles of the KICS case to Kaposi's sarcoma (KS) (n = 11) and non-KS (n = 6) cases. This KICS case presented with elevated levels of KSHV and IL-10, as expected. Surprisingly, this case did not have elevated levels of IL-6 or human immunodeficiency virus 1 (HIV-1). Nevertheless, treatment with anti-IL6 receptor antibody (tocilizumab) reduced KSHV viral load and IL-10. The KSHV genome sequence showed no significant changes over time, except in ORF24. Phylogenetic analysis established this isolate as belonging to KSHV clade A and closely related to other US isolates. These findings suggest IL-10 as potential biomarker and therapy target for KICS.

Tumor Microenvironment Conditioning by Abortive Lytic Replication of Oncogenic γ-Herpesviruses

Epstein Barr virus (EBV) and Kaposi sarcoma-associated herpesvirus (KSHV) constitute the human γ-herpesviruses and two of the seven human tumor viruses. In addition to their viral oncogenes that primarily belong to the latent infection programs of these viruses, they encode proteins that condition the microenvironment. Many of these are early lytic gene products and are only expressed in a subset of infected cells of the tumor mass. In this chapter I will describe their function and the evidence that targeting them in addition to the latent oncogenes could be beneficial for the treatment of EBV- and KSHV-associated malignancies.

Kaposi sarcoma

Kaposi sarcoma (KS) gained public attention as an AIDS-defining malignancy; its appearance on the skin was a highly stigmatizing sign of HIV infection during the height of the AIDS epidemic. The widespread introduction of effective antiretrovirals to control HIV by restoring immunocompetence reduced the prevalence of AIDS-related KS, although KS does occur in individuals with well-controlled HIV infection. KS also presents in individuals without HIV infection in older men (classic KS), in sub-Saharan Africa (endemic KS) and in transplant recipients (iatrogenic KS). The aetiologic agent of KS is KS herpesvirus (KSHV; also known as human herpesvirus-8), and viral proteins can induce KS-associated cellular changes that enable the virus to evade the host immune system and allow the infected cell to survive and proliferate despite viral infection. Currently, most cases of KS occur in sub-Saharan Africa, where KSHV infection is prevalent owing to transmission by saliva in childhood compounded by the ongoing AIDS epidemic. Treatment for early AIDS-related KS in previously untreated patients should start with the control of HIV with antiretrovirals, which frequently results in KS regression. In advanced-stage KS, chemotherapy with pegylated liposomal doxorubicin or paclitaxel is the most common treatment, although it is seldom curative. In sub-Saharan Africa, KS continues to have a poor prognosis. Newer treatments for KS based on the mechanisms of its pathogenesis are being explored.

Kaposi sarcoma-associated herpesvirus/human herpesvirus 8-associated lymphoproliferative disorders

Kaposi sarcoma-associated herpesvirus/human herpesvirus 8 is associated with multicentric Castleman disease (MCD) and primary effusion lymphoma (PEL). In MCD, infected B cells, although polyclonal, express a monotypic immunoglobulin Mλ phenotype, probably through editing toward λ light chain in mature B cells. They are considered to originate from pre-germinal center (GC) naive B cells. Both viral and human interleukin-6 contribute to the plasmacytic differentiation of these cells, and viral replication can be observed in some infected cells. PEL cells are clonal B cells considered as GC/post-GC B cells. One can also hypothesize that they originate from the same infected naive B cells and that additional factors could be responsible for their peculiar phenotype.

Kaposi's Sarcoma-Associated Herpesvirus (KSHV)-Associated Disease in the AIDS Patient: An Update

In this book chapter, we review the current knowledge of the biology and pathogenesis of Kaposi's sarcomaassociated herpesvirus (KSHV). We describe the lifecycle of KSHV, the cancers associated with this virus, as well as current treatment modalities.

Isolated retroperitoneal Castleman's disease: A case report and literature review

Unicentric Castleman's disease (CD) may rarely present as an isolated retroperitoneal tumor. Even experienced surgeons may misdiagnose CD because of its rarity. Surgeons should consider this disease when faced with an isolated retroperitoneal tumor. Unicentric CD is usually cured with surgical resection. In contrast, multicentric CD need numerous systemic therapies.

Renal failure in pediatric Castleman disease: Four French cases with thrombotic microangiopathy

Pediatric Castleman disease (CD) is an uncommon and poorly understood disorder of the lymph nodes. Renal failure has not been described in pediatric multicentric CD (MCD). We report four cases, who presented with polyadenopathy, organomegaly, edema and fluid accumulations, high blood pressure, and acute renal failure. In all cases, renal biopsy confirmed diffuse thrombotic microangiopathy. Definitive diagnosis of MCD was made by a biopsy of an affected lymph node located by computer tomography before initiation of corticosteroid therapy. Treatment of CD with corticosteroid therapy and rituximab was rapidly effective without relapse to date.

Human herpesvirus-encoded kinase induces B cell lymphomas in vivo

Kaposi's sarcoma-associated herpesvirus (KSHV) is a gammaherpesvirus that is the etiological agent of the endothelial cell cancer Kaposi's sarcoma (KS) and 2 B cell lymphoproliferative disorders, primary effusion lymphoma (PEL) and multicentric Castleman's disease (MCD). KSHV ORF36, also known as viral protein kinase (vPK), is a viral serine/threonine kinase. We previously reported that KSHV vPK enhances cell proliferation and mimics cellular S6 kinase to phosphorylate ribosomal protein S6, a protein involved in protein synthesis. We created a mouse model to analyze the function of vPK in vivo. We believe this is the first mouse tumor model of a viral kinase encoded by a pathogenic human virus. We observed increased B cell activation in the vPK transgenic mice compared with normal mice. We also found that, over time, vPK transgenic mice developed a B cell hyperproliferative disorder and/or a high-grade B cell non-Hodgkin lymphoma at a greatly increased incidence compared with littermate controls. This mouse model shows that a viral protein kinase is capable of promoting B cell activation and proliferation as well as augmenting lymphomagenesis in vivo and may therefore contribute to the development of viral cancers.

Kaposi sarcoma herpesvirus pathogenesis

Kaposi sarcoma herpesvirus (KSHV), taxonomical name human gammaherpesvirus 8, is a phylogenetically old human virus that co-evolved with human populations, but is now only common (seroprevalence greater than 10%) in sub-Saharan Africa, around the Mediterranean Sea, parts of South America and in a few ethnic communities. KSHV causes three human malignancies, Kaposi sarcoma, primary effusion lymphoma, and many cases of the plasmablastic form of multicentric Castleman's disease (MCD) as well as occasional cases of plasmablastic lymphoma arising from MCD; it has also been linked to rare cases of bone marrow failure and hepatitis. As it has colonized humans physiologically for many thousand years, cofactors are needed to allow it to unfold its pathogenic potential. In most cases, these include immune defects of genetic, iatrogenic or infectious origin, and inflammation appears to play an important role in disease development. Our much improved understanding of its life cycle and its role in pathogenesis should now allow us to develop new therapeutic strategies directed against key viral proteins or intracellular pathways that are crucial for virus replication or persistence. Likewise, its limited (for a herpesvirus) distribution and transmission should offer an opportunity for the development and use of a vaccine to prevent transmission.

This article is part of the themed issue ‘Human oncogenic viruses’.

HIV-Associated Cancers and Related Diseases

Clusters of cases of pneumocystis pneumonia and Kaposi’s sarcoma in New York and California in men who had sex with men were early harbingers of the acquired immunodeficiency syndrome (AIDS) epidemic.1 The syndrome was also soon noted to be associated with a high incidence of aggressive B-cell lymphomas. As the AIDS definition crystallized, Kaposi’s sarcoma, aggressive B-cell lymphomas, and invasive cervical cancer were considered to be AIDS-defining cancers when they developed in patients with human immunodeficiency virus (HIV) infection.2 Additional cancers are now known to be associated with HIV (Table 1 ). The term HIV-associated cancer is used here to describe this larger group of cancers (both AIDS-defining and non–AIDS-defining cancers) that have an increased incidence among patients with HIV infection. In addition, incidental cancers also may develop in patients with HIV infection.

GESIDA/PETHEMA recommendations on the diagnosis and treatment of lymphomas in patients infected by the human immunodeficiency virus

The incidence of non-Hodgkin's lymphoma and Hodgkin's lymphoma is higher in patients with HIV infection than in the general population. Following the introduction of combination antiretroviral therapy (cART), the prognostic significance of HIV-related variables has decreased, and lymphoma-related factors have become more pronounced. Currently, treatments for lymphomas in HIV-infected patients do not differ from those used in the general population. However, differentiating characteristics of seropositive patients, such as the need for cART and specific prophylaxis and treatment of certain opportunistic infections, should be considered. This document updates recommendations on the diagnosis and treatment of lymphomas in HIV infected patients published by GESIDA/PETHEMA in 2008.

Treatment of Kaposi Sarcoma Herpesvirus-Associated Multicentric Castleman Disease

Kaposi sarcoma herpesvirus (KSHV)-associated multicentric Castleman disease (MCD) is a rare, polyclonal lymphoproliferative disorder characterized by flares of inflammatory symptoms, edema, cytopenias, lymphadenopathy, and splenomegaly. Diagnosis requires a lymph node biopsy. Pathogenesis is related to dysregulated inflammatory cytokines, including human and viral interleukin-6. Rituximab alone or in combination with chemotherapy, such as liposomal doxorubicin, has led to an overall survival of over 90% at 5 years. Experimental approaches to treatment include virus activated cytotoxic therapy with high-dose zidovudine and valganciclovir and targeting human interleukin-6 activity. Despite successful treatment of KSHV-MCD, patients remain at high risk for developing non-Hodgkin lymphomas.