Virologic and immunologic parameters that predict clinical response of AIDS-associated Kaposi's sarcoma to highly active antiretroviral therapy

AMC-070: Lenalidomide Is Safe and Effective in HIV-Associated Kaposi Sarcoma

PURPOSE

Kaposi sarcoma (KS), an endothelial cell tumor associated with KS herpesvirus (KSHV), remains among the most common malignancies occurring with HIV infection (HIV-KS). As an oral anti-inflammatory, antiangiogenic, and immunomodulatory agent, lenalidomide is potentially an attractive alternative to standard chemotherapy for KS.

EXPERIMENTAL DESIGN

The primary objectives of this phase I/II trial were to determine the maximum tolerated dose (MTD) and response rates for lenalidomide in HIV-KS. Secondary objectives included correlating response with natural killer (NK) and T-cell subsets, plasma cytokines, viral copy number, and KSHV gene expression in biopsies. Four dose levels of oral lenalidomide taken 21 consecutive days of 28-day cycles were evaluated in adults with HIV-KS on antiretroviral therapy with controlled viremia.

RESULTS

Fifteen and 23 participants enrolled in phases I and II, respectively, 76% of whom had received prior KS therapy. The MTD was not reached, declaring 25 mg as the recommended phase II dose (RP2D). The most frequent adverse events were neutropenia, fatigue, leukopenia, and diarrhea. Of the 25 evaluable participants receiving RP2D, 60% responded. Correlative studies performed in a subset of participants demonstrated a significant increase in proportions of blood T cells with T-regulatory phenotype, and plasma cytokines trended toward a less inflammatory pattern. Clinical response was associated with loss of KSHV transcription.

CONCLUSIONS

Lenalidomide is active in HIV-KS. The most common adverse events were manageable. With 60% of participants receiving RP2D obtaining a partial response and <10% discontinuing due to adverse events, the response and tolerability to lenalidomide support its use in HIV-KS. See related commentary by Henry and Maki, p. 2485.

Effect of electrochemotherapy on human herpesvirus 8 kinetics in classic Kaposi sarcoma

BACKGROUND

Electrochemotherapy (ECT) has shown to be an effective treatment for cutaneous and subcutaneous Kaposi sarcoma (KS) lesions. However, no study has investigated the impact of ECT treatment on the kinetics of human herpesvirus type 8 (HHV8), which is considered the necessary causal agent of KS. We aimed to evaluate HHV8 viral load and expression levels in patients affected by classic KS who received one or more ECT treatments and have been followed semi annually for up to four years.

METHODS

A total of 27 classic KS patients were enrolled in this study. Tumour biopsies and blood samples were obtained before ECT treatment. Additional blood samples were collected at six month intervals for 12-48 months. HHV8 viral load and expression profiles of latent (ORF72 and ORF73) and lytic (K2, K8, K8.1, K10/K10.1, K10.5/K10.6 and ORF16) genes were assessed in all samples by real-time PCR. HHV8 ORF26 and K1 regions were amplified and subjected to direct nucleotide sequencing followed by phylogenetic analysis for variant identification.

RESULTS

All KS biopsies and 46.4% of peripheral blood mononuclear cells (PBMCs) collected before ECT treatment were positive for HHV8 DNA. Viral load ranged from 0.02 to 2.3 copies per cell in KS lesions and 3.0 × 10^-7 to 6.9 × 10^-4 copies per cell in PBMCs. Overall, latent ORF72 and ORF73 as well as lytic K2, K8 and K10/K10.1 were expressed in all KS biopsies. ORF16 mRNA was detected in 71.4% and both K8.1 and K10.5/K10.6 mRNAs in 57.1% of KS samples. The ORF72, ORF73 and K2 transcripts were amplified in 37.5%, 25% and 25% of PBMCs collected before ECT, respectively. After the first ECT session, complete response was achieved in 20 out of 27 (74.1%) patients and HHV8 DNA was detected in four out of 27 (14.8%) PBMC samples at six month follow up. Phylogenetic analysis of ORF26 amplimers showed that most viral variants belonged to A/C (82.3%), and few to C2 (5.9%) or C3 (11.8%) subtype. The K1/VR1 variants fell into A (33.3%) and C (66.7%) HHV8 clade. No correlation was found between HHV8 subtypes and ECT complete response.

CONCLUSIONS

ECT therapy has a significant effect on HHV8 kinetics in patients with classic KS. The complete remission of patients was accompanied by clearance of circulating virus.

Reactivation and Lytic Replication of Kaposi's Sarcoma-Associated Herpesvirus: An Update

The life cycle of Kaposi’s sarcoma-associated herpesvirus (KSHV) consists of two phases, latent and lytic. The virus establishes latency as a strategy for avoiding host immune surveillance and fusing symbiotically with the host for lifetime persistent infection. However, latency can be disrupted and KSHV is reactivated for entry into the lytic replication. Viral lytic replication is crucial for efficient dissemination from its long-term reservoir to the sites of disease and for the spread of the virus to new hosts. The balance of these two phases in the KSHV life cycle is important for both the virus and the host and control of the switch between these two phases is extremely complex. Various environmental factors such as oxidative stress, hypoxia, and certain chemicals have been shown to switch KSHV from latency to lytic reactivation. Immunosuppression, unbalanced inflammatory cytokines, and other viral co-infections also lead to the reactivation of KSHV. This review article summarizes the current understanding of the initiation and regulation of KSHV reactivation and the mechanisms underlying the process of viral lytic replication. In particular, the central role of an immediate-early gene product RTA in KSHV reactivation has been extensively investigated. These studies revealed multiple layers of regulation in activation of RTA as well as the multifunctional roles of RTA in the lytic replication cascade. Epigenetic regulation is known as a critical layer of control for the switch of KSHV between latency and lytic replication. The viral non-coding RNA, PAN, was demonstrated to play a central role in the epigenetic regulation by serving as a guide RNA that brought chromatin remodeling enzymes to the promoters of RTA and other lytic genes. In addition, a novel dimension of regulation by microPeptides emerged and has been shown to regulate RTA expression at the protein level. Overall, extensive investigation of KSHV reactivation and lytic replication has revealed a sophisticated regulation network that controls the important events in KSHV life cycle.

Kaposi's sarcoma-associated herpesvirus: the role of lytic replication in targeted therapy

PURPOSE OF REVIEW

To discuss the role of Kaposi's sarcoma-associated herpesvirus (KSHV) lytic replication in viral-associated diseases and assess the progress on targeting KSHV lytic replication as a strategy to prevent KSHV-related malignancies.

RECENT FINDINGS

New inhibitors of viral lytic replication are being developed as well as novel modalities are being investigated to target cellular processes that the virus hijacks during its life cycle. Research has also focused on reactivating viral lytic replication in latently infected tumour cells (lytic induction therapy) to promote death of tumour cells.

SUMMARY

KSHV is linked to three malignancies: Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman disease. Despite significant progress in understanding KSHV pathobiology, no therapeutic guidelines for the management of KSHV-related diseases exist, and current treatments are suboptimal and associated with toxicity. Antiherpesvirus drugs have shown inconsistent results in KSHV-associated malignancies that harbour the virus in a latent state. However, lytic replication plays a crucial role in the process of tumorigenesis. Therefore, not only antiviral agents directed against the virus replicative cycle but also agents that target cellular processes that are activated by the virus are being investigated. Antivirals may also be used in combination with inducers of the viral lytic stage.

Human gammaherpesviruses viraemia in HIV infected patients

BACKGROUND

The Epstein-Barr virus (EBV) and Kaposi's sarcoma associated herpesvirus (KSHV) are consistently associated with lymphoproliferative diseases and cancers in humans, notably in patients with HIV.

AIMS

Our aim was to evaluate whether EBV and/or KSHV viral loads regularly assessed in peripheral blood mononuclear cells (PBMC) correlate with clinical or laboratorial parameters retrieved for patients living with HIV.

METHODS

This was a longitudinal study with a cohort of 157 HIV positive patients attending an academic HIV outpatient clinic in São Paulo State, Brazil. For each patient, up to four blood samples were collected over a 1 year clinical follow-up: on enrolment into the study, and after 4, 8 and 12 months. Total DNA was extracted from PBMC, and EBV and KSHV viral loads were assessed by real time quantitative PCR.

RESULTS

Higher viral loads for EBV were significantly associated with high HIV viraemia, a greater number of circulating T CD8+ cells and lack of virological response to the antiretroviral treatment. KSHV viral load was undetectable in virtually all samples.

CONCLUSIONS

EBV viral load in PBMC correlated with the number of circulating T CD8+ lymphocytes and the response to the antiretroviral therapy in HIV infected patients. In contrast, KSHV was undetectable in PBMC, presumably an effect of the antiretroviral treatment. Therefore, either KSHV infection in the population studied was absent or viral load in PBMC was beyond the analytical limit of the assay.

Reduced human herpesvirus-8 oropharyngeal shedding associated with protease inhibitor-based antiretroviral therapy

BACKGROUND

Human herpesvirus 8 (HHV-8) replication increases the risk of Kaposi sarcoma (KS). Highly-active antiretroviral therapy (HAART) reduces the incidence of KS, and regimens that contain protease inhibitors (PIs) may be particularly effective.

OBJECTIVE

To determine whether PI-based HAART regimens may more effectively inhibit HHV-8 shedding compared to regimens without PIs.

STUDY DESIGN

Prospective, observational study of 142 HIV-1 and HHV-8 co-infected men conducted in Seattle, Washington. Quantitative HHV-8 PCR testing was performed on daily swabs of the oropharynx, the primary site of HHV-8 replication. Associations between antiretroviral regimen and detection of HHV-8 DNA in swabs were evaluated using generalized estimating equations.

RESULTS

HHV-8 DNA was detected in 3016 (26%) of 11,608 specimens collected. PI-based HAART was associated with a statistically significantly lower frequency of detection (RR 0.2; 95% CI 0.1-0.5) compared to ART-naïve persons, whereas HAART without a PI was not (RR 0.7; 95% CI 0.4-1.3). Compared to ART-naïve persons, there was also a trend toward lower quantities of HHV-8 detected during treatment with HAART regimens that contained a PI. These associations between PIs and measures of HHV-8 shedding could not be attributed to use of nelfinavir, which inhibits HHV-8 replication in vitro, and were independent of CD4 count and HIV plasma viral load (VL).

CONCLUSIONS

HAART regimens that contain PIs appear to decrease HHV-8 shedding compared to NNRTIs. Further study of PI-based HAART is warranted to determine the optimal regimens for prevention and treatment of KS.

Clinical outcomes of HIV-infected patients with Kaposi's sarcoma receiving nonnucleoside reverse transcriptase inhibitor-based antiretroviral therapy in Uganda

BACKGROUND

Clinical outcomes for patients with Kaposi's sarcoma (KS) using nonnucleoside reverse transcriptase inhibitor (NNRTI)-based highly active antiretroviral therapy (HAART) in resource-limited settings have not previously been described.

METHODS

We evaluated HIV-infected patients aged ≥ 18 years, who initiated HAART in the Home-Based AIDS Care (HBAC) project in Tororo, Uganda, between May 2003 and February 2008 and were diagnosed with KS at baseline or during follow-up. We examined independent risk factors for having either prevalent or incident KS and risk factors for death among patients with KS.

RESULTS

Of 1121 study subjects, 17 (1.5%) were diagnosed with prevalent KS and 18 (1.6%) with incident KS over a median of 56.1 months of follow-up. KS was associated with male sex [adjusted odds ratio (AOR) 2.41; 95% confidence interval (CI) 1.20-4.86] and baseline CD4 cell count < 50 cells/μL (AOR 3.25; 95% CI 1.03-10.3). Eleven (65%) of 17 patients with prevalent KS and 13 (72%) of 18 patients with incident KS experienced complete regression (P = 0.137). Eighteen (64%) of 28 patients who remained on NNRTI-based HAART experienced regression of their KS and six (86%) of seven patients who were switched to protease inhibitor-containing HAART regimens had regression of their KS (P = 0.23). Mortality among those with KS was significantly associated with visceral disease (hazard ratio 19.22; 95% CI 2.42-152).

CONCLUSION

Prevalent or incident KS was associated with 30% mortality. The resolution of KS lesions among individuals who initiated HAART with NNRTI-based regimens was similar to that found in studies using only protease inhibitor-based HAART.

Exposure to HIV-protease inhibitors selects for increased expression of P-glycoprotein (ABCB1) in Kaposi's sarcoma cells

Background:

Given that HIV-protease inhibitors (HIV-PIs) are substrates/inhibitors of the multidrug transporter ABCB1, can induce ABCB1 expression, and are used in combination with doxorubicin for AIDS-Kaposi's Sarcoma (KS) treatment, the role that ABCB1 plays in mediating multidrug resistance (MDR) in a fully transformed KS cell line (SLK) was explored.

Methods:

The KS cells were exposed to both acute and chronic treatments of physiological concentrations of different HIV-PIs (indinavir, nelfinavir, atazanavir, ritonavir, or lopinavir), alone or together with doxorubicin. The ABCB1 mRNA and protein expression levels were then assessed by qRT–PCR and western blotting, flow cytometry, and immunofluorescence.

Results:

Chronic treatment of SLK cells with one of the five HIV-PIs alone or together resulted in increased resistance to doxorubicin. Co-treatment with one of the HIV-PIs in combination with doxorubicin resulted in a synergistic increase in resistance to doxorubicin, and the degree of resistance was found to correlate with the expression of ABCB1. The SLK cells were also revealed to be cross-resistant to the structurally unrelated drug paclitaxel.

Conclusion:

These studies suggest that ABCB1 is primarily responsible for mediating MDR in SLK cells selected with either HIV-PIs alone or in combination with doxorubicin. Therefore, the roles that ABCB1 and drug cocktails play in mediating MDR in KS in vivo should be evaluated.

Human herpesvirus 8-associated neoplasms: the roles of viral replication and antiviral treatment

PURPOSE OF REVIEW

In this review, we highlight the importance of human herpesvirus 8 (HHV-8) lytic replication and the potential for antiviral therapies to prevent or treat HHV-8-related neoplasms.

RECENT FINDINGS

Diseases caused by HHV-8 infection include Kaposi sarcoma, multicentric Castleman disease (MCD), and primary effusion lymphoma (PEL), which occur primarily in patients with HIV infection. Kaposi sarcoma is the most common AIDS-associated malignancy worldwide. MCD and PEL occur less commonly but, like Kaposi sarcoma, are associated with poor treatment outcomes. Like all herpesviruses, HHV-8 is capable of either latent or lytic infection of cells. Although HHV-8 infection of tumor cells is predominately latent, accumulating data point to the importance of both lytic phase viral gene products and production of infectious virus. Antiviral agents that target herpesvirus DNA synthesis, such as ganciclovir, inhibit HHV-8 lytic replication and can prevent Kaposi sarcoma. Several HIV protease inhibitors may interfere with tumor growth and angiogenesis, and one protease inhibitor, nelfinavir, directly inhibits HHV-8 replication in vitro.

SUMMARY

Controlled trials are indicated to determine the clinical utility of antiviral suppression of HHV-8 replication, and identify the optimal antiretroviral regimens, for the prevention and treatment of Kaposi sarcoma.

Risk factors influencing antibody responses to Kaposi's sarcoma-associated herpesvirus latent and lytic antigens in patients under antiretroviral therapy

BACKGROUND

Kaposi's sarcoma-associated herpesvirus (KSHV) seropositivity and lytic antibody titer are predictors for Kaposi's sarcoma.

METHODS

We examined demographic, viral, and immunologic factors that influence KSHV latent and lytic antibodies in HIV-infected patients.

RESULTS

Detection rate of KSHV latent but not lytic antibodies was lower in patients with CD4 cells/mm3 less than 200 than greater than 200 (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.11-0.61) and CD8 cells/mm3 less than 400 than greater than 400 (OR, 0.26; 95% CI, 0.07-0.67). Overall seropositivity rate was higher in patients with CD4 cells/mm3 less than 200 than greater than 200 (OR, 2.34; 95% CI, 1.37-4.02) and HIV copies/mL greater than 400 than less than 400 (OR, 1.70; 95% CI, 1.09-2.65). Lytic antibody level was inversely correlated with CD4 count (P < 0.001). Lytic seropositivity (OR, 2.47; 95% CI, 1.35-4.50) and antibody level (adjusted difference mean optical density, 0.324; 95% CI, 0.16-0.46) were higher in patients with HIV infection greater than 15 than less than 15 years. Hispanics had higher lytic seropositivity rate (OR, 1.71; 95% CI, 1.07-2.73) and antibody level (adjusted difference mean optical density, 0.111; 95% CI, 0.03-0.18) than non-Hispanics.

CONCLUSIONS

Lower CD4 and CD8 counts impair antibody response to KSHV latent antigens. Immune deterioration, long-term HIV infection, and Hispanic status are risk factors for Kaposi's sarcoma predictors.

Risk of classic Kaposi sarcoma with exposures to plants and soils in Sicily

Background

Ecologic and in vitro studies suggest that exposures to plants or soil may influence risk of Kaposi sarcoma (KS).

Methods

In a population-based study of Sicily, we analyzed data on contact with 20 plants and residential exposure to 17 soils reported by 122 classic KS cases and 840 sex- and age-matched controls. With 88 KS-associated herpesvirus (KSHV) seropositive controls as the referent group, novel correlates of KS risk were sought, along with factors distinguishing seronegatives, in multinomial logistic regression models that included matching variables and known KS cofactors - smoking, cortisone use, and diabetes history. All plants were summed for cumulative exposure. Factor and cluster analyses were used to obtain scores and groups, respectively. Individual plants and soils in three levels of exposure with P_trend ≤ 0.15 were retained in a backward elimination regression model.

Results

Adjusted for known cofactors, KS was not related to cumulative exposures to 20 plants [per quartile adjusted odds ratio (OR_adj) 0.96, 95% confidence interval (CI) 0.73 - 1.25, P_trend = 0.87], nor was it related to any factor scores or cluster of plants (P = 0.11 to 0.81). In the elimination regression model, KS risk was associated with five plants (P_trend = 0.02 to 0.10) and with residential exposure to six soils (P_trend = 0.01 to 0.13), including three soils (eutric regosol, chromic/pellic vertisol) used to cultivate durum wheat. None of the KS-associated plants and only one soil was also associated with KSHV serostatus. Diabetes was associated with KSHV seronegativity (OR_adj 4.69, 95% CI 1.97 - 11.17), but the plant and soil associations had little effect on previous findings that KS risk was elevated for diabetics (OR_adj 7.47, 95% CI 3.04 - 18.35) and lower for current and former smokers (OR_adj 0.26 and 0.47, respectively, P_trend = 0.05).

Conclusions

KS risk was associated with exposure to a few plants and soils, but these may merely be due to chance. Study of the effects of durum wheat, which was previously associated with cKS, may be warranted.

Cellular immune responses and disease control in acute AIDS-associated Kaposi's sarcoma

Kaposi's sarcoma-associated herpesvirus (KSHV) specific T cell responses and KSHV viremia were analyzed in seven HIV-infected patients with active Kaposi's sarcoma lesions who initiated highly active antiretroviral therapy, and were compared between patients with improved Kaposi's sarcoma and those with progressive Kaposi's sarcoma requiring further systemic chemotherapy. Patients with controlled Kaposi's sarcoma disease demonstrated undetectable Kaposi's sarcoma viremia together with KSHV-specific CD8 T cells secreting interferon-gamma and tumor necrosis factor-alpha, whereas progressors showed increasing viremia with weak or no T-cell responses. These data point toward a potential role of KSHV-specific immunity in the control of AIDS-associated Kaposi's sarcoma.

A Retrospective Analysis of AIDS-Associated Kaposi’s Sarcoma in Patients With Undetectable HIV Viral Loads and CD4 Counts Greater Than 300 cells/mm3

Objective: To compare the clinical course of patients with AIDS-related Kaposi’s sarcoma (KS) with CD4 counts >300 cells/mm3 and undetectable HIV viral loads (VLs) to patients with AIDS-KS with lesser CD4 counts and detectable HIV VLs.

Methods: We retrospectively analyzed a cohort of 91 patients with AIDS-KS in a multispeciality clinic. We used χ2 and Student t tests to analyze intragroup differences; survival was determined by Kaplan-Meier analysis.

Results: Twenty (22%) of the 91 patients had newly diagnosed, persistent or progressive KS despite CD4 counts >300 cells/mm3 and undetectable HIV VLs. Age, gender, ethnicity, mode and duration of HIV acquisition, type of antiretroviral therapy (ART), and KS therapy did not differ significantly (P ≤ .005) between this group and the remaining 71 patients. Although tumor stage and response to KS therapy were similar, there was a significantly greater risk of death among the patients with CD4 counts <300 cells/mm3 and detectable HIV VLs (P = .048).

Conclusions: In the highly active antiretroviral (HAART) era, a substantial proportion of patients with KS had undetectable HIV VLs and CD4 counts greater than the level typically associated with opportunistic diseases. They required systemic therapy to control their KS but were significantly less likely to die and demonstrated a trend toward better 15-year survival than patients having KS with lesser CD4 counts and detectable HIV VLs.

HHV8 a subtype is associated with rapidly evolving classic Kaposi's sarcoma

The link between human herpesvirus 8 (KSHV) and Kaposi's sarcoma (KS) has been proven, but many important aspects including risk factors, genetic predisposition to tumor development, transmission of KSHV, and the pathogenic potential of different genotypes remain to be elucidated. Possible associations between clinical parameters and antibody levels, viral load fluctuations, and viral genotype were analyzed by quantitative real-time PCR, an in-house developed IFA assay, and sequence analysis of ORF K1-VR1 in blood, serum and saliva of 38 subjects with classic KS (cKS). KSHV lytic antibodies were significantly increased in stage IV compared to stage I and II patients (p = 0.006 and p = 0.041, respectively). KSHV blood, serum, and saliva viral load was comparable in all stages. The highest viral loads were detected in saliva, and they decreased in stages III-IV compared to stages I-II patients. Higher concentrations of lytic antibodies and higher viral loads were observed in fast progressing cKS patients, in whom KSHV detection from blood was also more frequent. Type A KSHV strain was almost exclusively present in rapid progressors (12/17 cases), while C type was mainly present in slow progressing patients (6/7 cases). Finally, detection of type A KSHV strain associated with higher blood viral loads. KSHV lytic antibody levels and viral load can be used to monitor clinical evolution of cKS. Infection supported by KSHV A subtype is associated with more rapid progressive disease. Careful monitoring and aggressive therapeutic protocols should be considered in patients with KSHV A-supported infection.

Long-term prognosis of HIV-infected patients with Kaposi sarcoma treated with pegylated liposomal doxorubicin

INTRODUCTION

Incidence of Kaposi sarcoma (KS) in human immunodeficiency virus (HIV)-infected persons has dramatically decreased in the highly active antiretroviral therapy era. However, this tumor still represents the most common cancer in this population.

OBJECTIVES

The objectives of this study were to evaluate long-term prognosis of HIV-infected patients with KS who had received pegylated liposomal doxorubicin (PLD) and, more specifically, to assess tumor relapse rate, mortality, and cause of death in these subjects.

DESIGN

This study was a retrospective review of all patients with KS who had received PLD in centers belonging to the Caelyx/KS Spanish Group. Kaplan-Meier analysis and univariate and multivariate Cox-regression analysis were used to assess the rate of and factors associated with relapse and death through January 2006.

RESULTS

A total of 98 patients received PLD from September 1997 through June 2002. Median follow-up after initiation of treatment was 28.7 months (interquartile range, 6.6-73.2 months); during follow-up, 29 patients died (a mortality rate of 14.6% per year). In 9 patients (31%), the cause of death was related to the appearance of other tumors (including 7 lymphomas, 1 gastrointestinal adenocarcinoma, and 1 tongue epidermoid cancer). Death caused by progression of KS occurred in 3 cases. Death risk was inversely related to CD4(+) cell counts at the end of follow-up (hazard ratio for every increase in CD4(+) cell count of 100 cells/microL, 0.7; 95% confidence interval, 0.5-0.9). A relapse study was performed for 61 patients who had complete or partial response to PLD and who attended a control visit after treatment completion. After a median follow-up of 50 months (interquartile range, 17.2-76 months), 8 patients (13%) had experienced relapse; 5 of these patient experienced relapse within the first year after stopping PLD. The only factor that was independently related to risk of relapse was having a CD4(+) cell count >200 cells/microL at baseline (hazard ratio, 6.2; 95% confidence interval, 1.2-30). Lower CD4(+) cell count at the end of follow-up was marginally associated with relapse (hazard ratio for every increase in CD4(+) cell count of 100 cells/microL, 0.7; 95% confidence interval, 0.6-1.01).

CONCLUSIONS

Treatment of KS with PLD in HIV-infected patients is followed by a low relapse rate, with most relapses occurring during the first year after stopping chemotherapy. However, the mortality rate in this population was high, in part because of an unexpectedly high incidence of other tumors, mainly lymphomas.

The effects of human herpesvirus 8 infection and interferon-gamma response in cutaneous lesions of Kaposi sarcoma differ among human immunodeficiency virus-infected and uninfected individuals

BACKGROUND

Kaposi sarcoma (KS) is associated with human herpesvirus 8 (HHV-8). The cutaneous immune response in this tumour is not well established and a better understanding is necessary.

OBJECTIVES

To evaluate the HHV-8 expression and immune response in cutaneous lesions of classic KS (CKS) and AIDS-associated KS (AIDS-KS).

METHODS

We performed a quantitative immunohistochemical study of cells expressing HHV-8 latency-associated nuclear antigen (LANA), CD4, CD8 and interferon (IFN)-gamma in skin lesions from patients with CKS and AIDS-KS (with or without highly active antiretroviral therapy, HAART).

RESULTS

CKS showed higher LANA expression compared with AIDS-KS, regardless of HAART. We also found higher LANA expression in nodules compared with patch/plaque lesions. The tissue CD4+ cell proportion was lower in AIDS-KS patients without HAART than in patients with CKS. In CKS lesions, CD4+ and CD8+ cells expressed IFN-gamma, as shown by double immunostaining. AIDS-KS presented low numbers of IFN-gamma-expressing cells. CD8+ cell numbers were similar in all groups, which appeared unrelated to the clinical or epidemiological type of KS.

CONCLUSIONS

Our quantitative data on the pattern of KS lesions in selected groups of patients, as shown by in situ immune response, demonstrated a CD4+ T-cell involvement associated with IFN-gamma, an environment of immune response-modified human immunodeficiency virus (HIV) infection. In our sample, the promotion of KS in patients without HIV appears to be related to higher HHV-8 load or virulence than in those with AIDS. This higher resistance may be explained by a sustained immune response against this herpesvirus, that is only partially restored but effective after HAART.

Predicting the evolution of Kaposi sarcoma, in the highly active antiretroviral therapy era

BACKGROUND

The outcome of Kaposi sarcoma varies. While many patients do well on highly active antiretroviral therapy, others have progressive disease and need chemotherapy. In order to predict which patients are at risk of unfavorable evolution, we established a prognostic score.

METHOD

The survival analysis (Kaplan-Meier method; Cox proportional hazards models) of 144 patients with Kaposi sarcoma prospectively included in the Swiss HIV Cohort Study, from January 1996 to December 2004, was conducted. OUTCOME ANALYZED: use of chemotherapy or death. VARIABLES ANALYZED: demographics, tumor staging [T0 or T1 (16)], CD4 cell counts and HIV-1 RNA concentration, human herpesvirus 8 (HHV8) DNA in plasma and serological titers to latent and lytic antigens.

RESULTS

Of 144 patients, 54 needed chemotherapy or died. In the univariate analysis, tumor stage T1, CD4 cell count below 200 cells/microl, positive HHV8 DNA and absence of antibodies against the HHV8 lytic antigen at the time of diagnosis were significantly associated with a bad outcome. Using multivariate analysis, the following variables were associated with an increased risk of unfavorable outcome: T1 [hazard ratio (HR) 5.22; 95% confidence interval (CI) 2.97-9.18], CD4 cell count below 200 cells/microl (HR 2.33; 95% CI 1.22-4.45) and positive HHV8 DNA (HR 2.14; 95% CI 1.79-2.85). We created a score with these variables ranging from 0 to 4: T1 stage counted for two points, CD4 cell count below 200 cells/microl for one point, and positive HHV8 viral load for one point. Each point increase was associated with a HR of 2.26 (95% CI 1.79-2.85).

CONCLUSION

In the multivariate analysis, staging (T1), CD4 cell count (<200 cells/microl), positive HHV8 DNA in plasma, at the time of diagnosis, predict evolution towards death or the need of chemotherapy.

Persistent Kaposi sarcoma in the era of highly active antiretroviral therapy: characterizing the predictors of clinical response

OBJECTIVES

To evaluate the role of highly active antiretroviral therapy and chemotherapy on tumor response among persons with AIDS-related Kaposi sarcoma and identify factors associated with response in a clinic setting.

DESIGN

Retrospective cohort.

METHODS

One hundred and fourteen patients from two HIV clinics with a diagnosis of Kaposi sarcoma were identified via a clinical database. Records were reviewed to confirm Kaposi sarcoma diagnosis and abstract clinical and chemotherapy information. Demographics, laboratory values, and highly active antiretroviral therapy use were abstracted electronically. Cox's proportional hazards models identified predictors of Kaposi sarcoma improvement and resolution.

RESULTS

Thirty-six months following Kaposi sarcoma diagnosis, the rate of improvement among 64 patients with confirmed Kaposi sarcoma was 77% and that of complete resolution was 51%. In univariate analyses, recent chemotherapy was associated with Kaposi sarcoma improvement, and recent HIV viral load and highly active antiretroviral therapy were associated with both improvement and resolution. No measured baseline characteristics (tumor stage, diagnosis year, CD4 T-cell count, HIV viral load, or prior highly active antiretroviral therapy history) or recent CD4 T-cell counts predicted improvement or resolution. In multivariate analyses, recent chemotherapy (hazard ratio 5.5, 95% confidence interval: 2.7-11.2, P < 0.001) and highly active antiretroviral therapy (hazard ratio 4.1, 95% confidence interval: 1.4-12.6, P = 0.01) were predictors of improvement; only recent highly active antiretroviral therapy was associated with resolution (hazard ratio 6.2, 95% confidence interval: 1.5-26.4, P = 0.01). Response was not associated with type of highly active antiretroviral therapy regimen (non nucleoside reverse transcriptase inhibitor based, protease inhibitor based, or ritonavir-boosted protease inhibitor based).

CONCLUSION

Highly active antiretroviral therapy and chemotherapy are important in clinical Kaposi sarcoma response. Despite widespread availability of these therapies, Kaposi sarcoma continues to be a clinical problem; only half the patients achieved complete resolution of disease. New therapeutic approaches are needed.

Human herpesvirus 8 load and progression of AIDS-related Kaposi sarcoma lesions

INTRODUCTION

Human herpesvirus 8 (HHV8) is necessary for Kaposi sarcoma (KS) to develop, but whether peripheral blood viral load is a marker of KS burden (total number of KS lesions), KS progression (the rate of eruption of new KS lesions), or both is unclear. We investigated these relationships in persons with AIDS.

METHODS

Newly diagnosed patients with AIDS-related KS attending Mulago Hospital, in Kampala, Uganda, were assessed for KS burden and progression by questionnaire and medical examination. Venous blood samples were taken for HHV8 load measurements by PCR. Associations were examined with odds ratio (OR) and 95% confidence intervals (CI) from logistic regression models and with t-tests.

RESULTS

Among 74 patients (59% men), median age was 34.5 years (interquartile range [IQR], 28.5-41). HHV8 DNA was detected in 93% and quantified in 77% patients. Median virus load was 3.8 logs10/10(6) peripheral blood cells (IQR 3.4-5.0) and was higher in men than women (4.4 vs. 3.8 logs; p=0.04), in patients with faster (>20 lesions per year) than slower rate of KS lesion eruption (4.5 vs. 3.6 logs; p<0.001), and higher, but not significantly, among patients with more (>median 20 KS lesions) than fewer KS lesions (4.4 vs. 4.0 logs; p=0.16). HHV8 load was unrelated to CD4 lymphocyte count (p=0.23).

CONCLUSIONS

We show significant association of HHV8 load in peripheral blood with rate of eruption of KS lesions, but not with total lesion count. Our results suggest that viral load increases concurrently with development of new KS lesions.

Insights into pathogenic events of HIV-associated Kaposi sarcoma and immune reconstitution syndrome related Kaposi sarcoma

A decrease in the incidence of human immune deficiency virus-associated Kaposi sarcoma (HIV-KS) and regression of some established HIV-KS lesions is evident after the introduction of highly active anti-retroviral treatment (HAART), and is attributed to generalized immune restoration, to the reconstitution of human herpesvirus (HHV)-8 specific cellular immune responses, and to the decrease in HIV Tat protein and HHV-8 loads following HAART. However, a small subset of HIV-seropositive subjects with a low CD4+ T cell count at the time of introduction of HAART, may develop HIV-KS as immune reconstitution inflammatory syndrome (IRIS) within 8 weeks thereafter.

Phase 2 study of pegylated liposomal doxorubicin in combination with interleukin-12 for AIDS-related Kaposi sarcoma

Thirty-six patients with AIDS-associated Kaposi sarcoma (KS) requiring chemotherapy were treated for six 3-week cycles of pegylated liposomal doxorubicin (20 mg/m(2)) plus interleukin-12 (IL-12; 300 ng/kg subcutaneously twice weekly), followed by 500 ng/kg subcutaneous IL-12 twice weekly for up to 3 years. All received highly active antiretroviral therapy (HAART). Twenty-two had poor-prognosis KS (T(1)S(1)). Thirty patients had a major response, including 9 with complete response, yielding an 83.3% major response rate (95% confidence interval: 67.2%-93.6%). Median time to first response was 2 cycles. Median progression was not reached at median potential follow-up of 46.9 months. Of 27 patients with residual disease when starting maintenance IL-12, 15 had a new major response compared with this new baseline. The regimen was overall well tolerated; principal toxicities were neutropenia, anemia, transaminitis, and neuropsychiatric toxicity. Patients had increases in serum IL-12, interferon gamma, and inducible protein-10 (IP-10), and these remained increased at weeks 18 and 34. The regimen of IL-12 plus liposomal doxorubicin yielded rapid tumor responses and a high response rate in patients with AIDS-KS receiving HAART, and responses were sustained on IL-12 maintenance therapy. A randomized trial of IL-12 in this setting may be warranted. This study is registered at (http://www.clinicaltrials.gov) as no. NCT00020449.

Kaposi's sarcoma-associated herpesvirus-specific immune reconstitution and antiviral effect of combined HAART/chemotherapy in HIV clade C-infected individuals with Kaposi's sarcoma

BACKGROUND

Kaposi's sarcoma-associated herpesvirus (KSHV) is endemic in South Africa and the clinical manifestation of AIDS-associated Kaposi's sarcoma (KS) represents a significant clinical problem. Whereas the positive effects of HAART on the regression of KS have been well established, less is known about the role of herpesvirus-specific cellular immunity in disease improvement.

DESIGN

Thirty-three treatment-naive HIV clade C-infected individuals with KS were randomly assigned into two treatment arms (HAART plus systemic chemotherapy versus HAART alone). KSHV-specific cellular immune responses, viral loads and clinical outcome were evaluated.

METHODS

KSHV, Epstein-Barr virus and HIV-specific cellular immunity was measured using an IFN-gamma enzyme-linked immunospot assay in samples obtained at baseline and up to 11 months after treatment initiation. Cell-associated KSHV viremia was determined by real-time polymerase chain reaction.

RESULTS

Robust increases in CD4 cell counts and suppressed HIV viral loads were seen in parallel with significant increases in the KSHV-specific cellular immune responses over time. Although slowly increasing after 5 months, KSHV-specific T-cell responses were significantly elevated only after 11 months, with both lytic and latent antigens being more frequently targeted. A trend towards better clinical outcome with HAART plus chemotherapy treatment was observed compared with HAART alone, and was accompanied by a significant reduction in cellular KSHV viral load in the HAART plus chemotherapy-treated subjects but not those treated with HAART alone after 11 months of treatment.

CONCLUSION

The data show a temporal association between the clinical improvement of KS and the re-appearance of KSHV-specific cellular immunity, and demonstrate an effective suppression of KSHV viral replication using combination therapy.

Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 ORF50/Rta lytic switch protein functions as a tetramer

The Kaposi's sarcoma-associated herpesvirus open reading frame 50 (ORF50) protein (called Rta), is necessary and sufficient for reactivation of the virus from latency. We previously demonstrated that a truncated mutant of ORF50 lacking its C-terminal transcriptional activation domain, called ORF50DeltaSTAD, formed mixed multimers with wild-type (WT) ORF50 and functioned as a dominant negative inhibitor of reactivation. For this report, we investigated the requirements for multimerization of ORF50/Rta in transactivation and viral reactivation. We analyzed multimerization of WT, mutant, and chimeric ORF50 proteins, using Blue Native polyacrylamide gel electrophoresis and size exclusion chromatography. WT and mutant ORF50 proteins form tetramers and higher-order multimers, but not monomers, in solution. The proline-rich, N-terminal leucine heptapeptide repeat (LR) of ORF50 (amino acids [aa] 244 to 275) is necessary but not sufficient for oligomer formation and functions in concert with the central portion of ORF50/Rta (aa 245 to 414). The dominant negative mutant ORF50DeltaSTAD requires the LR to form mixed multimers with WT ORF50 and inhibit its function. In the context of the WT ORF50/Rta protein, mutagenesis of the LR, or replacement of the LR by heterologous multimerization domains from the GCN4 or p53 proteins, demonstrates that tetramers of Rta are sufficient for transactivation and viral reactivation. Mutants of Rta that are unable to form tetramers but retain the ability to form higher-order multimers are reduced in function or are nonfunctional. We concluded that the proline content, but not the leucine content, of the LR is critical for determining the oligomeric state of Rta.

The use of antiviral drugs in the prevention and treatment of Kaposi sarcoma, multicentric Castleman disease and primary effusion lymphoma

Kaposi sarcoma-associated herpesvirus [KSHV, also known as human herpesvirus 8 (HHV-8)] is the most recently identified member of the human herpesvirus family. Kaposi sarcoma (KS), primary effusion lymphoma, and multicentric Castleman disease are all associated with KSHV infection. Although the incidence of KS has declined dramatically in areas with access to highly active antiretroviral therapy, it remains the most common AIDS-associated malignancy in the developed world and is one of the most common cancers in developing nations. Current treatment options for KSHV-associated disease are ineffective, unavailable, or toxic to many affected persons. A growing body of basic science, preclinical, and observational data suggests that antiviral medications may play an important role in the prevention and treatment of KSHV-associated disease.

Systemic treatment of AIDS-related Kaposi sarcoma: current status and perspectives

Kaposi's sarcoma (KS) is the most frequent type of cancer in patients with Acquired Immune Deficiency Syndrome (AIDS). In the western world, its incidence decreased dramatically in the era of highly active anti-retroviral therapy (HAART). In contrast, the incidence of KS has been steadily climbing in parallel with the AIDS epidemic in Africa over the past 10-15 years, being the most common cancer in adult men in countries like Uganda and Zimbabwe. AIDS-KS can be diagnosed at any stage of HIV infection, although it more commonly occurs in the setting of severe immune suppression, especially with an elevated viral load. Up to now, AIDS-KS is still an incurable disease. Its clinical course is variable, ranging from very indolent cases, requiring no or minimal therapy, to a rapidly progressive disease. Various local therapies are available to control small and asymptomatic lesions, while cytotoxic, immunological and biological therapies can be considered for more aggressive disease. The primary goal of therapy in most of the cases is to provide safe and effective palliation, in order to quality of life. Optimal anti-retroviral therapy is a key component of AIDS-KS management. There are still many questions to be answered in the management of patients with AIDS-KS, such as (1) What are the therapeutic agents that should be used in this disease, and in which sequence? and (2) What are the benefits and risks expected with each treatment option? The aim of this review is to discuss the systemic management of AIDS-KS, with special focus on the above mentioned questions.

Kaposi's sarcoma-associated herpesvirus viremia is associated with the progression of classic and endemic Kaposi's sarcoma

In order to gain further insight on the role of Kaposi's sarcoma-associated herpesvirus (KSHV) in classic and endemic Kaposi's sarcoma (KS) pathogenesis, we aimed to determine (i) whether KSHV is detectable in peripheral blood mononuclear cells (PBMCs), (ii) which PBMCs subpopulation harbor the virus, (iii) which clinical, histologic, and immunologic parameters are associated with KSHV viremia in a population of classic and endemic KS. KSHV viremia and various immunologic parameters were screened on 81 patients. KSHV viremia was positive in 58% of the patients. KSHV was detected in B cells, T cells, and monocytes. CD34+ cells depleted in circulating endothelial cells (CECs) were never infected and 50% of the patients tested had CECs infected by KSHV. We observed a significant increase of IL-2 and IFN-gamma production by CD4 T cells and an increase of IFN-gamma production by CD8 T cells compared to control patients. KS progression (P = 0.001) and KS staging (P = 0.03) were significantly and independently associated with positive KSHV viremia. Our results show that there is no specific immunosuppression in classic or endemic KS. We showed that KSHV can be detected within CECs and that KSHV viremia could be an indicator of circulating mature or precursor spindle cells.

Cutaneous malignancy and human immunodeficiency virus disease

Certain skin cancers occur with increased frequency or altered course in patients infected with HIV. Malignant melanoma and squamous cell carcinoma are examples of cutaneous malignancies that have a more aggressive course in patients with HIV. Others, such as basal cell carcinoma, appear more frequently in this population but do not appear to be more aggressive. The incidence of HIV-associated Kapsosi's sarcoma has markedly decreased since the advent of HIV antiretroviral therapy. Our understanding of the pathogenesis of this malignancy and its unique management issues are fully reviewed. Cutaneous T-cell lymphoma (CTCL) is rare in this population. Other types of cutaneous lymphoma and HIV-associated pseudo-CTCL are discussed. This article addresses prevention, treatment, and follow-up strategies for this at-risk population.

LEARNING OBJECTIVE

At the completion of this learning activity, participants should be familiar with the unique epidemiology, clinical course, and management of cutaneous malignancy in patients infected with HIV.

Biomarkers in cancer staging, prognosis and treatment selection

Advances in genomics, proteomics and molecular pathology have generated many candidate biomarkers with potential clinical value. Their use for cancer staging and personalization of therapy at the time of diagnosis could improve patient care. However, translation from bench to bedside outside of the research setting has proved more difficult than might have been expected. Understanding how and when biomarkers can be integrated into clinical care is crucial if we want to translate the promise into reality.

Approach to the treatment of cutaneous malignancy in HIV-infected patients

Patients infected with human immunodeficiency virus (HIV) have an increased risk of developing skin cancers. These at-risk patients may have atypical presentations and/or altered clinical courses. This article will review and discuss management issues for the following malignancies: lymphomas, malignant melanoma, basal cell carcinoma, squamous cell carcinoma, and Kaposi's sarcoma.

Evidence for both lytic replication and tightly regulated human herpesvirus 8 latency in circulating mononuclear cells, with virus loads frequently below common thresholds of detection

To address whether human herpesvirus 8 (HHV-8) DNA in peripheral blood mononuclear cells (PBMCs) might be the product of latent or lytic infection and to shed light on sporadic detection of HHV-8 DNA in individuals seropositive for the virus, we studied the frequency of infected cells, total virus load, and virus load per infected cell in PBMCs from men coinfected with HHV-8 and human immunodeficiency virus (HIV), some of whom had Kaposi's sarcoma. The low frequencies of infected cells detected (fewer than one per million cells in some individuals) suggest that the prevalence of the virus in circulating leukocytes was underestimated in previous studies that employed more conventional sampling methods (single, small-volume specimens). Mean virus loads ranged from 3 to 330 copies per infected PBMC; these numbers can represent much higher loads in individual lytically infected cells (>10(3) genomes/cell) in mixtures that consist predominantly of latently (relatively few genomes) infected cells. The presence in some subjects of high HHV-8 mean genome copy numbers per infected cell, together with viral DNA being found in plasma only from subjects with positive PBMCs, supports earlier suggestions that the virus can actively replicate in PBMCs. In some individuals, mean virus loads were less than 10 genomes per infected cell, suggesting a tightly controlled purely latent state. HHV-8 genome copy numbers are substantially higher in latently infected cells derived from primary effusion lymphomas; thus, it appears that HHV-8 is able to adopt more than one latency program, perhaps analogous to the several types of Epstein-Barr virus latency.

Antitumour effects of antiretroviral therapy

Infection by human immunodeficiency virus (HIV) is associated with an increased risk of certain tumours, particularly Kaposi's sarcoma, non-Hodgkin's lymphomas and cervical cancer. However, the incidence of these tumours in HIV-infected patients has decreased significantly since the widespread use of highly active antiretroviral therapy (HAART). This effect cannot be solely explained by the ability of these drugs to suppress HIV replication and thereby reconstitute the immune system. Recent studies have shown that inhibitors of the HIV aspartyl protease, which are widely used in HAART, have direct anti-angiogenic and antitumour effects that are unrelated to their antiviral activity. So these drugs might be used to treat cancer in patients who are not infected with HIV.

Multicentric Castleman's disease and Kaposi's sarcoma in a cyclosporin treated, HIV-1 negative patient: case report

Background

Multicentric Castleman's disease (MCD) is a rare disease, but is more frequent in AIDS patients. MCD has only been reported twice before in patients receiving immunosuppressive therapy after renal transplantation, and never in patients receiving immunosuppressive therapy without transplantation. About half of the cases of MCD are human herpesvirus 8 (HHV8) – related, in contrast to Kaposi's sarcoma, a more common complication arising after immunosuppression, where the virus is found in virtually all cases.

Case presentation

We report a HIV-1 negative, non-transplant patient who developed HHV8-associated multicentric Castleman's disease and Kaposi's sarcoma after 17 years of immunosuppressive treatment with cyclosporin A for a minimal change nephropathy. Chemotherapy with liposomal doxorubicin resolved both symptoms of multicentric Castleman's disease and Kaposi's sarcoma in this patient. A concomitant decline in the HHV8 viral load in serum/plasma, as determined by a quantitative real-time PCR assay, was observed.

Conclusions

Multicentric Castleman's disease can be a complication of cyclosporin A treatment. Both multicentric Castleman's disease and Kaposi's sarcoma in this patient were responsive to liposomal doxorubicin, the treatment of choice for Kaposi's sarcoma at the moment, again suggesting a common mechanism linking both disorders, at least for HHV8-positive multicentric Castleman's disease and Kaposi's sarcoma.

HHV8 viral load measurements can be used to monitor effectiveness of therapy.

Isolated intraparotid Kaposi sarcoma in human immunodeficiency virus type 1 infection

Isolated Kaposi sarcoma (KS) of the parotid gland is an uncommon but distinct entity in patients with human immunodeficiency virus type 1 (HIV-1). A 30-year-old white homosexual man in whom HIV-1 had been diagnosed 2 years previously developed right parotid gland enlargement in the absence of constitutional symptoms. He had been taking zidovudine, lamivudine, and indinavir; his CD4 cell count was 0.297 x 10(9)/L, and HIV-1 RNA load was 47 copies/mL. After surgical excision of the parotid gland, biopsy findings disclosed KS of an intraparotid lymph node. A literature review revealed 6 other men with HIV-1 and isolated parotid KS. To our knowledge, our patient is the first to have received triple antiretroviral therapy with excellent immunological and virological response and parotid gland enlargement that might reflect immune reconstitution. Even in the absence of skin or other lesions, KS should be considered in the differential diagnosis of parotid gland enlargement in patients with HIV-1, even in those who are responding to highly active antiretroviral treatment.

AIDS-related Kaposi's Sarcoma: evaluation of potential new prognostic factors and assessment of the AIDS Clinical Trial Group Staging System in the Haart Era--the Italian Cooperative Group on AIDS and Tumors and the Italian Cohort of Patients Naive From Antiretrovirals

PURPOSE

To assess potential new prognostic factors and to validate the AIDS Clinical Trials Group (ACTG) for AIDS-related Kaposi's sarcoma (AIDS-KS) staging system in the highly active antiretroviral therapy (HAART) era.

PATIENTS AND METHODS

We collected epidemiologic, clinical, staging, and survival data from 211 patients with AIDS-KS enrolled in two prospective Italian human immunodeficiency virus (HIV) cohort studies. We included in the analysis all patients with the diagnosis of KS made from January 1996, the time at which HAART became available in Italy.

RESULTS

In the univariate analysis, survival was not influenced by sex, age, level of HIV viremia at KS diagnosis, HAART at KS diagnosis (HAART-naïve v HAART-experienced), or type of HAART combination. Regarding ACTG classification, the 3-year survival rate was 85% for T0 patients and 69% for T1 patients (P =.007), 83% for S0 patients and 63% for S1 patients (P =.003), and 83% for I0 patients and 71% for I1 patients (P =.06). In the multivariate analysis, only the combination of poor tumor stage (T1) and poor systemic disease (S1) risk identified patients with unfavorable prognosis. The 3-year survival rate of patients with T1S1 was 53%, which was significantly lower compared with the 3-year survival rates of patients with T0S0, T1S0, and T0S1, which were 88%, 80%, and 81%, respectively (P =.0001).

CONCLUSION

In the era of HAART, a refinement of the original ACTG staging system is needed. CD4 level does not seem to provide prognostic information. Two different risk categories are identified: a good risk (T0S0, T1S0, T0S1) and a poor risk (T1S1).

Molecular genetics of Kaposi's sarcoma-associated herpesvirus (human herpesvirus-8) epidemiology and pathogenesis

Kaposi's sarcoma had been recognized as unique human cancer for a century before it manifested as an AIDS-defining illness with a suspected infectious etiology. The discovery of Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus-8, in 1994 by using representational difference analysis, a subtractive method previously employed for cloning differences in human genomic DNA, was a fitting harbinger for the powerful bioinformatic approaches since employed to understand its pathogenesis in KS. Indeed, the discovery of KSHV was rapidly followed by publication of its complete sequence, which revealed that the virus had coopted a wide armamentarium of human genes; in the short time since then, the functions of many of these viral gene variants in cell growth control, signaling apoptosis, angiogenesis, and immunomodulation have been characterized. This critical literature review explores the pathogenic potential of these genes within the framework of current knowledge of the basic herpesvirology of KSHV, including the relationships between viral genotypic variation and the four clinicoepidemiologic forms of Kaposi's sarcoma, current viral detection methods and their utility, primary infection by KSHV, tissue culture and animal models of latent- and lytic-cycle gene expression and pathogenesis, and viral reactivation from latency. Recent advances in models of de novo endothelial infection, microarray analyses of the host response to infection, receptor identification, and cloning of full-length, infectious KSHV genomic DNA promise to reveal key molecular mechanisms of the candidate pathogeneic genes when expressed in the context of viral infection.