A phase II study of recombinant human interferon-alpha 2a and zidovudine in patients with AIDS-related Kaposi's sarcoma. AIDS Clinical Trials Group

Cytokine-Targeted Therapeutics for KSHV-Associated Disease

Kaposi's sarcoma-associated herpesvirus (KSHV) also known as human herpesvirus 8 (HHV-8), is linked to several human malignancies including Kaposi sarcoma (KS), primary effusion lymphoma (PEL), multicentric Castleman's disease (MCD) and recently KSHV inflammatory cytokine syndrome (KICS). As with other diseases that have a significant inflammatory component, current therapy for KSHV-associated disease is associated with significant off-target effects. However, recent advances in our understanding of the pathogenesis of KSHV have produced new insight into the use of cytokines as potential therapeutic targets. Better understanding of the role of cytokines during KSHV infection and tumorigenesis may lead to new preventive or therapeutic strategies to limit KSHV spread and improve clinical outcomes. The cytokines that appear to be promising candidates as KSHV antiviral therapies include interleukins 6, 10, and 12 as well as interferons and tumor necrosis factor-family cytokines. This review explores our current understanding of the roles that cytokines play in promoting KSHV infection and tumorigenesis, and summarizes the current use of cytokines as therapeutic targets in KSHV-associated diseases.

AIDS-Related Kaposi Sarcoma, Version 2.2019, NCCN Clinical Practice Guidelines in Oncology

As treatment of HIV has improved, people living with HIV (PLWH) have experienced a decreased risk of AIDS and AIDS-defining cancers (non-Hodgkin's lymphoma, Kaposi sarcoma, and cervical cancer), but the risk of Kaposi sarcoma in PLWH is still elevated about 500-fold compared with the general population in the United States. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for AIDS-Related Kaposi Sarcoma provide diagnosis, treatment, and surveillance recommendations for PLWH who develop limited cutaneous Kaposi sarcoma and for those with advanced cutaneous, oral, visceral, or nodal disease.

Interferon-alpha2b with protease inhibitor-based antiretroviral therapy in patients with AIDS-associated Kaposi sarcoma: an AIDS malignancy consortium phase I trial

We evaluated the safety and maximum tolerated dose of interferon (IFN)-alpha2b in combination with protease inhibitor-based highly active antiretroviral therapy (HAART) in a phase 1 study in 14 patients with AIDS-associated Kaposi sarcoma (KS). Planned IFN dose levels were 0, 1, 5, 10, and 15 million IU administered by daily subcutaneous injection. Dose-limiting toxicities were neutropenia and malaise. The maximum tolerated IFN dose was 5 million IU/d. The median CD4 count increased from 260 cells/muL at baseline to a maximum on-study value of 359 cells/muL. In 6 patients with paired baseline and on-study values, the median HIV RNA level decreased from 20,179 copies/mL to a minimum on-study value of 309 copies/mL. Of 13 patients whose KS response could be evaluated, 5 showed objective tumor regression. Responses occurred in HAART-experienced and HAART-naive subjects. Five patients, including 2 responders, 2 with stable KS, and 1 with progression, had serial measurements of Kaposi sarcoma herpesvirus (KSHV) load. None of these patients, irrespective of treatment arm or KS response, showed durable clearance of KSHV from plasma or peripheral blood mononuclear cells. This study establishes a safe dose of IFN that can be used with HAART and, potentially, with other inhibitors of KS in future clinical trials.

Targeting human herpesvirus-8 for treatment of Kaposi??s sarcoma and primary effusion lymphoma

PURPOSE OF REVIEW

Human herpesvirus-8, also called the Kaposi's sarcoma herpesvirus, is present in all cases of Kaposi's sarcoma and primary effusion lymphoma and in some cases of multicentric Castleman's disease. This review discusses mechanisms by which human herpesvirus-8 contributes to tumorigenesis and how this knowledge can be used to target the virus for the treatment of these tumors.

RECENT FINDINGS

Most primary effusion lymphomas and Kaposi's sarcoma tumor cells are latently infected with human herpesvirus-8 and hence resistant to antiherpesvirus drugs that are dependent on lytic replication. In contrast, many of the cells infected with human herpesvirus-8 in multicentric Castleman's disease support lytic replication, so that clinical improvement frequently occurs in response to treatment with antiherpesvirus drugs. The resistance of latently-infected tumor cells to antiherpesvirus drugs can be overcome by inducing human herpesvirus-8 to reenter the lytic cascade in the presence of antiherpesvirus drugs. This leads to apoptosis of virally infected cells without increasing production of infectious virus. Alternatively, the replication and maintenance of the human herpesvirus-8 episome during latency can be disrupted by glycyrrhizic acid or hydroxyurea so that the virus no longer contributes to tumorigenesis. Both the innate and acquired immune systems can also be augmented to help prevent or treat human herpesvirus-8-associated tumors.

SUMMARY

Novel strategies targeting human herpesvirus-8, which is present in all cases of Kaposi's sarcoma and primary effusion lymphoma, provide opportunities for selectively killing tumor cells.

Use of liposomal anthracyclines in Kaposi’s sarcoma

Conventional chemotherapy regimens for the treatment of advanced Kaposi's sarcoma (KS) show limited efficacy and considerable toxicity. Liposomal anthracyclines with potential utility in KS include pegylated liposomal doxorubicin (Doxil/Caelyx [PLD]), daunorubicin citrate liposome (DaunoXome [DNX]), and nonpegylated liposomal doxorubicin (Myocet [NPLD]). Preclinical data showed that pegylated liposomes accumulate preferentially in highly vascularized KS lesions. In randomized clinical trials, PLD induced higher response rates than did the conventional combination chemotherapy regimens, bleomycin + vincristine (BV) and BV + conventional doxorubicin (ABV); DNX produced a response rate comparable to that of ABV. NPLD has not been compared with conventional chemotherapy for KS. PLD and DNX were associated with less toxicity compared with BV or ABV, including less alopecia and fewer gastrointestinal and neurologic side effects. Grade 3/4 myelosuppression was common with both PLD and DNX; stomatitis and infusion reactions occurred with PLD treatment, but hand-foot syndrome was relatively infrequent in the dose schedules used for KS. Health-related quality of life was improved in several domains in patients treated with PLD or DNX compared with ABV.

Inhibition of infectious human herpesvirus 8 production by gamma interferon and alpha interferon in BCBL-1 cells

Human herpesvirus-8 (HHV-8) is aetiologically linked to Kaposi's sarcoma and primary effusion lymphoma. Although interferon-alpha (IFN-alpha) and interferon-gamma (IFN-gamma) are both antiviral cytokines, IFN-alpha blocks entry of HHV-8 into the lytic phase, whereas IFN-gamma induces an increase in the percentage of cells undergoing lytic replication. Multiple events in the lytic cascade must be completed to produce infectious virus. The ability of both types of IFN to affect the production of infectious virus was explored. Both IFN-alpha and IFN-gamma induced expression of the antiviral proteins double-stranded RNA-activated protein kinase (PKR) and 2'5'-oligoadenylate synthetase (2'5'-OAS) in HHV-8-infected BCBL-1 cells. Higher levels resulted from incubation with IFN-alpha than with IFN-gamma, whereas IFN-gamma induced higher levels of IRF-1 than did IFN-alpha. IFN-gamma induced a minor increase in lytic viral gene expression, which was not accompanied by a detectable increase in infectious virus. When lytic replication of HHV-8 was induced using TPA, high levels of infectious virus appeared in the conditioned medium. When IFN-gamma was present during TPA stimulation, the production of infectious virus was reduced by at least a 60 %, and IFN-alpha fully blocked TPA-induced production of infectious virus. The greater reduction of viral production that occurred with IFN-alpha is consistent with the higher levels of the antiviral proteins PKR and 2'5'-OAS induced by IFN-alpha than by IFN-gamma. These studies indicate that the augmentation of cellular antiviral defences by IFN-gamma was sufficient to prevent production of infectious virus despite IFN-gamma-induced entry of some cells into the lytic phase of HHV-8 replication.

Clinical presentations and standard therapy of AIDS-associated Kaposi's sarcoma

The treatment plan for a patient with AIDS-related KS should be based on tumor characteristics, control of HIV infection, comorbidities, and patient treatment goals (see Table 1). Institution of optimal antiretroviral therapy is an essential component of KS therapy. When available, enrollment in a clinical trial should be considered, except for patients who are naive to chemotherapy with symptomatic or life-threatening KS. For a patient with minimal, indolent cutaneous disease, after optimal control of HIV replication, local treatment, investigational treatment, or interferon are reasonable considerations. For the patient with rapidly progressive, cutaneous disease, tumor-related symptoms, or visceral disease, cytotoxic chemotherapy in combination with antiretroviral therapy is the first consideration. Future advances undoubtedly will include pathogenesis-based agents, either alone or in combination with currently available cytotoxic therapy.

Potential of interferon-alpha in solid tumours: part 2

The second part of this review examines the use of recombinant interferon-alpha (rIFNalpha) in the following solid tumours: superficial bladder cancer, Kaposi's sarcoma, head and neck cancer, gastrointestinal cancers, lung cancer, mesothelioma and ovarian, breast and cervical malignancies. In superficial bladder cancer, intravesical rIFNalpha has a promising role as second-line therapy in patients resistant or intolerant to intravesical bacille Calmette-Guérin (BCG). In HIV-associated Kaposi's sarcoma, rIFNalpha is active as monotherapy and in combination with antiretroviral agents, especially in patients with CD4 counts >200/mm(3), no prior opportunistic infections and nonvisceral disease. rIFNalpha has shown encouraging results when used in combination with retinoids in the chemoprevention of head and neck squamous cell cancers. It is effective in the chemoprevention of hepatocellular cancer in hepatitis C-seropositive patients. In neuroendocrine tumours, including carcinoid tumour, low-dosage (</=3 MU) or intermediate-dosage (5 to 10 MU) rIFNalpha is indicated as second-line treatment, either with octreotide or alone in patients resistant to somatostatin analogues. Intracavitary IFNalpha may be useful in malignant pleural effusions from mesothelioma. Similarly, intraperitoneal IFNalpha may have a role in the treatment of minimal residual disease in ovarian cancer. In breast cancer, the only possible role for IFNalpha appears to be intralesional administration for resistant disease. IFNalpha may have a role as a radiosensitising agent for the treatment of cervical cancer; however, this requires confirmation in randomised trials. On the basis of current evidence, the routine use of rIFNalpha is not recommended in the therapy of head and neck squamous cell cancers, upper gastrointestinal tract, colorectal and lung cancers, or mesothelioma. Pegylated IFNalpha (peginterferon-alpha) is an exciting development that offers theoretical advantages of increased efficacy, reduced toxicity and improved compliance. Further data from randomised studies in solid tumours are needed where rIFNalpha has activity, such as neuroendocrine tumours, minimal residual disease in ovarian cancer, and cervical cancer. A better understanding of the biological mechanisms that determine response to rIFNalpha is needed. Studies of IFNalpha-stimulated gene expression, which are now feasible, should help to identify molecular predictors of response and allow us to target therapy more selectively to patients with solid tumours responsive to IFNalpha.

Viral kinetics of hepatitis C virus RNA in patients with chronic hepatitis C treated with 18 MU of interferon alpha daily

BACKGROUND

A rapid decrease of hepatitis C virus (HCV) RNA is interferon (IFN) dose-dependent, and a 3-log decline of HCV-RNA is a strong predictor of sustained virological response. In this study, viral kinetics of HCV RNA in patients treated with 18 MU interferon alpha (IFN-alpha) daily for 2 weeks are presented.

METHODS

Thirteen treatment-naive patients with chronic hepatitis C received 6 MU of IFN-alpha2a every 8 h for 2 weeks. Samples were obtained daily during the treatment period. HCV-RNA levels were determined using the quantitative VERSANT 3.0 bDNA assay (detection limit 520 IU/ml). When results were below the detection limit, HCV-RNA was measured by qualitative polymerase chain reaction (PCR) using the COBAS AMPLICOR HCV test, version 2.0 (detection limit of 50 IU/ml).

RESULTS

In patients infected with genotype non-1, a 3-log decline of viral load was found 2.4 days after the start of induction therapy. Only one of three patients infected with genotype 1 had a 3-log decline in viral load within 14 days of the start of therapy. In four patients, a third phase of viral decline was observed. At the end of treatment, 10/13 (77%) and 7/13 (54%) patients were HCV-RNA-negative in quantitative assay and qualitative PCR, respectively. Only one of 13 patients achieved a sustained virological response (SVR).

CONCLUSION

Daily administration of 18 MU IFN-alpha to patients infected with genotype non-1 induces a 3-log decline of viral load within 2.4 days of the start of treatment. In patients infected with genotype 1, only one-third of patients have a 3-log decline at 11 days.

AIDS and non-AIDS-related malignancies: a new vexing challenge in HIV-positive patients. Part I: Kaposi's sarcoma, non-Hodgkin's lymphoma, and Hodgkin's lymphoma

HIV-infected patients are at an increased risk for developing cancers. Three, in particular, are considered to be AIDS-defining malignancies: Kaposi's sarcoma (KS), non-Hodgkin's lymphoma (NHL), and cervical cancer. Other non-AIDS-defining malignancies have been reported in the setting of HIV infection as having an increased frequency compared with their incidence in the general population. One of those most frequently reported is Hodgkin's disease. As with KS and NHL, the problem of diagnosing and treating immunocompromised patients with cancer represents a formidable challenge. Moreover, a newly discovered human gamma-herpes virus, human herpes virus-8 (HHV-8), has been identified in over 90% of KS lesions from patients with and without AIDS, suggesting its etiological importance in the development of KS and new therapeutic approaches.

Efficacy of low-dose interferon with antiretroviral therapy in Kaposi's sarcoma: a randomized phase II AIDS clinical trials group study

We wished to evaluate the efficacy and safety of a low and an intermediate daily dose of interferon-alpha2b (IFN-alpha2b) with didanosine in patients with acquired immunodeficiency syndrome (AIDS)-associated Kaposi's sarcoma (KS). HIV-seropositive subjects with biopsy-confirmed cutaneous KS were randomized to receive either a low (1 million IU) or an intermediate (10 million IU) dose of IFN-alpha2b once daily with twice daily doses of didanosine. Treatment assignment was stratified by CD4 count. Response, toxicity, changes in CD4 counts, and survival were evaluated. Sixty-eight eligible subjects were accrued, 35 to low-dose and 33 to intermediate-dose IFN-alpha2b. The response rate was 40% in the low-dose group (95% CI, 24-58) and 55% in the intermediate-dose group (95% CI, 36-72) (p = 0.338). The median response duration was approximately 110 weeks in both groups. Intermediate-dose IFN induced grade 3/4 neutropenia more often (21% vs. 3%, p = 0.048) and grade 3/4 toxicity faster (p = 0.0231) and necessitated treatment discontinuation earlier for drug-related toxicities (p = 0.0416) than low-dose IFN. There were no significant differences in survival between the treatment groups. Baseline CD4 count was the only significant factor predicting response. Once-daily low-dose and intermediate-dose IFN-alpha2b induced similar response rates, which were achieved without optimal antiretroviral therapy. The slightly higher response rate in the intermediate-dose group was offset by its significantly poorer tolerance. These findings justify the use of lower, well-tolerated IFN doses for treatment of KS with currently used antiretroviral regimens.

Management of Kaposi sarcoma: the role of interferon and thalidomide

Kaposi sarcoma (KS) remains the most commonly diagnosed cancer in HIV-infected patients. Although several chemotherapeutic agents have proven effective in controlling KS, the growing understanding of the factors contributing to the development of KS has provided a stronger rationale for using noncytotoxic agents that influence the mechanisms involved in KS pathogenesis. Two such agents, interferon and thalidomide, have shown activity against KS in clinical trials and have the potential to influence multiple steps believed to be important in KS development and progression. Studies are ongoing to explore the optimal way to use these agents and their mechanisms of action.

Contradictory Concepts in the Etiology and Regression of Kaposi's Sarcoma. The Ferenc Györkey Memorial Lecture

The Introduction is an overview of 3 decades of works performed by Professor Ferenc Györkey (in many cases in collaboration with the author) and aimed at the elucidation of viral participation in the etiology of arteriosclerosis, SLE, hairy cell leukemia, HD, AIDS and KS. Controversial issues surrounding the etiology, treatment and regression of KS are discussed in terms of paracrine and autocrine loops of growth factors; protooncogene-oncogene activations, immunosuppression and retro- and/or herpesviral etiology. In regressing KS lesions the roles played by Fas, Bcl-2, Bax, TNFß; apoptotic-antiapoptotic events; and antiangiogenesis agents especially that of Hu-r-IFNa are elaborated on.

Antiangiogenic strategies and agents in clinical trials

The understanding that the growth of tumors depends on the acquisition of a blood supply has led to the development of new therapies for cancer and other angiogenic diseases based on inhibition of neovascularization. This review examines the role of angiogenesis in cancer progression and describes various strategies for interfering with this process. The developmental status of angiogenesis inhibitors in human clinical trials is presented, including their proposed mechanisms of action. Standard chemotherapeutic agents and angiogenesis inhibitors are compared, noting that different end points might need to be considered in clinical trials and that drug resistance may be less of a problem with antiangiogenic therapy than with conventional chemotherapy regimens. The suggestion is made that cytotoxic chemotherapy and angiogenesis inhibitors used in combination may produce complementary therapeutic benefits in the treatment of cancer.

Highly active anti-retroviral therapy (HAART) prolongs time to treatment failure in Kaposi's sarcoma

OBJECTIVE

To evaluate the impact of highly active antiretroviral therapy (HAART) on Kaposi's sarcoma.

DESIGN

Retrospective study of patients who had received systemic or local treatment for AIDS-related Kaposi's sarcoma who subsequently commenced HAART.

METHODS

Case note review to determine time to treatment failure for Kaposi's sarcoma before and after starting HAART. Time to treatment failure was calculated from the end of last therapy to the start of the next new treatment for Kaposi's sarcoma.

RESULTS

The cohort contained 78 patients. Only 38% had good risk Kaposi's sarcoma (stage T0I0) at presentation. The median time to treatment failure before starting HAART was 0.5 years. Initial HAART therapy was three or more drugs including a protease inhibitor for 38 (49%), three or more drugs without a protease inhibitor for 27 (35%) and a two-drug protease combination for 13 (16%). The median follow-up after starting HAART was 12 months (range, 0.5-52 months) and anti-Kaposi's sarcoma treatment has been required for 24 (31%) patients. The median time to treatment failure for Kaposi's sarcoma from the start of HAART is 1.7 years. This is statistically longer than the time to treatment failure for the same cohort of patients before they started HAART (log rank chi2 = 16.5, P < 0.0001). The serum HIV RNA viral load (VL) at the time of Kaposi's sarcoma progression revealed virological failure of HAART (defined as VL > 5000 copies/ml) in 14 of 24 (58%) and good control (VL < 200 copies/ml) in five of 24 (21%).

CONCLUSION

HAART is associated with prolonged time to treatment failure in Kaposi's sarcoma. Progression of Kaposi's sarcoma while on HAART is not necessarily associated with virological failure as determined by rising viral RNA titre.

A randomized trial of interferon-α2a and zidovudine versus bleomycin and zidovudine for AIDS-related Kaposi's sarcoma

The efficacy and toxicity of interferon-α2a (9MU/d) and bleomycin (15 mg every 2 weeks), each combined with zidovudine (2 × 250 mg/d), was compared in a randomized study in 26 men with progressing AIDS-related Kaposi's sarcoma (KS). The median CD4 count was 113/μl. Complete or partial response was achieved in one (8%) of 12 evaluable patients on interferon and in 2 (20%) of 10 patients on bleomycin (P=0.43) during 4.7 and 5.3 months of treatment, respectively. The tolerability was comparable. During extended follow up, survival time was 24 and 13 months in the interferon and bleomycin arm, respectively. In a multivariate Cox regression analysis, CD4 lymphocytes <200/μl (relative risk 3.74; 95% CI: 1.30–10.8) and randomization to interferon (relative risk 0.37; 95% CI: 0.15–0.90) were significantly predictive of mortality. New AIDS-related events occurred more frequently in patients who had received bleomycin. The antiviral activity of interferon-α or the chemotherapy-mediated increase in the risk for opportunistic infections may explain these differences.

Phase II, randomized, open-label, community-based trial to compare the safety and activity of combination therapy with recombinant interferon-alpha2b and zidovudine versus zidovudine alone in patients with asymptomatic to mildly symptomatic HIV infection. HIV Protocol C91-253 Study Team

OBJECTIVES

To compare, in a community-based therapeutic setting, the safety, tolerance, and efficacy of combination therapy with recombinant interferon-alpha2b (rIFN-alpha2b) and zidovudine (ZDV) to ZDV monotherapy.

DESIGN

Open-label, two-armed, randomized study.

PATIENTS AND METHODS

Asymptomatic or minimally symptomatic HIV-infected adults without an AIDS-defining illness, a CD4 count of 200 to 500 cells/microl, and < or = 6 months of prior ZDV therapy received ZDV 100 mg orally five times daily. Patients randomized to rIFN-alpha2b received 3 million IU subcutaneously three times weekly for 2 weeks and 5 million IU three times weekly thereafter. The groups were compared with respect to adverse events (AEs), dosing modifications, treatment discontinuation, clinical endpoints and changes in CD4 count. A virology substudy compared the treatments with respect to HIV viral load and development of ZDV resistance.

RESULTS

Between October, 1991 and January, 1993, 139 patients were randomized to combination therapy and 117 to ZDV alone. Of AEs reported at any grade, fatigue, myalgias, and sweating occurred significantly more often with combination therapy (p < .001). Study subjects receiving combination therapy showed modest but significantly greater weight loss (p = .0001), a significantly higher frequency of any abnormal laboratory test result (p = .002), neutropenia (p = .002), and leukopenia (p = .02), and also required dosage reduction for hematologic toxicity significantly more often (p < .05) than those in the ZDV monotherapy arm. No statistically significant differences were found between the groups with respect to development of specific AIDS-defining events, overall event rate, time to events, or change in performance status or CD4+ counts, or percentages or development of ZDV resistance. Viral burden, reflected by serum p24 antigen and quantitative peripheral blood mononuclear cell (PBMC) microcultures, was greater at baseline in the combination therapy group. Baseline SI phenotype predicted progression to AIDS (p = .004, chi2), whereas intermediate susceptibility to ZDV predicted development of ZDV resistance (p < .005, chi2). The annual rate of development of phenotypic resistance to ZDV was 16.8% and was not affected by administration of rIFN-alpha2b.

CONCLUSIONS

At the doses and schedule used in this study, the combination of ZDV with rIFN-alpha2b was not therapeutically superior to ZDV alone and was less well tolerated. The addition of rIFN-alpha2b to ZDV did not prevent or delay the development of ZDV resistance.

Clinical overview: issues in Kaposi's sarcoma therapeutics

Four questions are posed that are critical to the development of improved therapeutic and prophylactic strategies for Kaposi's sarcoma (KS). 1) Can we predict who will develop KS? Accurate identification of high-risk factors for KS development is essential for the development of KS prophylaxis trials. 2) Can developing insights into KS pathogenesis be translated into improved therapeutic and/or new prophylactic strategies for patients at high risk? Several approaches are being developed that target new blood vessel development, inflammatory cytokines, and the viruses that are implicated in KS pathogenesis. 3) How does the improved prognosis for human immunodeficiency virus (HIV)-infected patients affect KS treatment strategy? Improved anti-HIV therapy has implications for the timing of KS therapy, the choice of therapeutic approaches, and the potential for adverse drug interactions. 4) How can we best evaluate benefits from KS treatment? More rigorous, standardized criteria are in development and will be essential not only for accurate documentation of objective tumor regression, but also for assessment of tumor-associated symptom relief in a quantitative, function-oriented way.

Interferons in dermatology. Present-day standard

Since the first clinical trials in the early 1980s with recombinant interferon, it was possible to show for a variety of indications that cytokines, especially interferons, at certain doses and at respective intervals, when applied in combination with other pharmaceutical compounds open new powerful therapeutic possibilities. Worldwide, recombinant interferon is licensed, especially in dermato-oncology, for the indication of HIV-associated Kaposi's sarcoma, cutaneous T-cell lymphoma, and recently for adjuvant therapy of high-risk malignant melanoma. Recombinant interferon is at present not licensed for dermatologic indication (septic granulomatosis). At the end of our century the indication spectrum for interferons as monotherapy and as combination therapy will undoubtedly be extended. Larger and controlled studies will prove the importance of interferons in dermato-oncology as well as in inflammatory and infectious dermatoses. The combination of interferons with standard therapies will surely be of the utmost importance in dermatotherapy.

Acquired immunodeficiency syndrome-associated Kaposi's sarcoma. Biology and management

Kaposi's Sarcoma (KS), the most common AIDS-associated malignancy, occurs with increased frequency in all HIV transmission groups, but at a particularly high rate in homosexual men. Recent studies suggest that KS pathogenesis involves exposure to an infectious agent, altered expression and response to cytokines, and modulation of growth by HIV gene products. KS varies in its clinical presentation from a relatively indolent process to a widely disseminated, aggressive disease. A variety of local and systemic treatments provide effective, but usually temporary, disease palliation. Insights into KS pathogenesis suggest a number of targeted therapeutic approaches that may eventually lead to improved disease management and disease cure.

Antiviral activity of biological response modifiers in a murine model of AIDS. Requirement for augmentation of natural killer cell activity and synergy with oral AZT

We employed the Rauscher murine leukemia virus (RMuLV) as a murine retrovirus model of AIDS, to test biological response modifiers (BRM) and antiviral agents for potential therapeutic activity against the human immunodeficiency virus (HIV). We examined the relationship between the augmentation of natural killer (NK) cell activity and antiviral efficacy of a series of BRM, most of which are known inducers of interferon, in this model. Poly [I,C]-LC, MVE-2, and CL 246,738, but not Ampligen, soluble glucan, or 7-thia-8-oxoguanosine, consistently produced antiviral activity. In addition, the combination of suboptimal doses of oral 3'-azido-3'-deoxythymidine (AZT) (in drinking water) and poly [I,C]-LC produced a synergistic antiviral effect. With all the BRM tested, a consistent pattern emerged, namely that antiviral activity always correlated with the augmentation of splenic NK cell activity in infected animals. For instance, poly [I,C]-LC boosted NK activity much more in infected mice treated therapeutically (treatment initiated after infection) than prophylactically (treatment initiated before infection), and it had greater antiviral activity therapeutically than prophylactically. For the BRM tested, antiviral activity did not occur without augmentation of NK activity in infected mice. In contrast, augmentation of NK activity in uninfected mice bore no relationship to antiviral activity. Furthermore, elimination of NK cells by treating mice with anti-asialo GM1 abolished the antiviral activity of poly [I,C]-LC. Although splenic NK activity was ablated by anti-asialo GM1, serum interferon levels were not affected by this treatment. These results point to a causal connection between the augmentation of NK cell activity and the antiviral efficacy of these BRM in this murine AIDS model. NK cells thus appear to play a key role in resistance to this retrovirus, as has been suggested for HIV.