Low-dose interferon alpha combined with zidovudine in patients with AIDS-associated Kaposi's sarcoma

Interferons: role in cancer therapy

Interferons (IFNs) are a group of signaling cytokines, secreted by host cells to induce protection against various disorders. IFNs can directly impact on tumor cells or indirectly induce the immune system to protect host cells. The expression levels of IFNs and its functions of are excellently modulated in a way to protect host cells from probable toxicities caused by extreme responses. The efficacy of anticancer therapies is correlated to IFNs signaling. Although IFN signaling is involved in induction of antitumor responses, chronic stimulation of the IFN signaling pathway can induce resistance to various antineoplasm therapies. Hence, IFNs are expressed by both cancer and immune cells, and modulate their biological function. Understanding this mechanism of action might be a key target of combination therapies.

Gene therapy with plasmids encoding IFN-β or IFN-α14 confers long-term resistance to HIV-1 in humanized mice

Because endogenous interferon type I (IFN-I) produced by HIV-1 infection might complicate the analysis of therapeutically administered IFN-I, we tested different humanized mouse models for induction of IFN-I during HIV-1 infection. While HIV-1 induced high levels of IFN-α in BLT mice, IFN-I was undetectable following infection in the Hu-PBL mouse model, in which only T cells expand. We therefore tested the effect of treatment with Pegylated IFN-2 (pegasys), in Hu-PBL mice. Pegasys prevented CD4 T cell depletion and reduced the viral load for 10 days, but the effect waned thereafter. We next expressed IFN-I subsets (IFN-α2, −α6, −α8, −α14, and −β) in Hu-PBL mice by hydrodynamic injection of plasmids encoding them and 2 days later infected the mice with HIV-1. CD4 T cell depletion was prevented in all subtypes of IFN-I-expressing mice by day 10. However, at day 40 post-infection, protection was seen in IFN-β- and IFN-α14-expressing mice, but not the others. The viral load followed an inverse pattern and was highest in control mice and lowest in IFN-β- and IFN-α14-expressing mice until day 40 after infection. These results show that gene therapy with plasmids encoding IFN-β and −α14, but not the commonly used −α2, confers long-term suppression of HIV-1 replication.

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.

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.

The antiviral drug docosanol as a treatment for Kaposi's sarcoma lesions in HIV type 1-infected patients: a pilot clinical study

Docosanol inhibits a broad spectrum of lipid-enveloped viruses in vitro including HSV-1, HSV-2, VZV, CMV, HHV-6, and HIV-1. These observations led us to conduct a pilot clinical study with docosanol 10% cream as a topical treatment for Kaposi's sarcoma (KS) in HIV-1-infected patients. In this open-label study 28 cutaneous KS lesions in 10 HIV-1-infected patients were treated topically five times daily for 4 weeks with evaluation of lesion characteristics of area, edema, and color. All patients elected to enroll in an extended treatment protocol and continued to treat for up to 35 weeks. Within 28 days, 2 of 10 patients exhibited a partial response based on standardized criteria exhibiting 74 to 83% reductions in total target lesion areas. With extended treatment, a partial response was exhibited in two additional patients where total target lesion area was reduced by 52% in one patient and target lesions in another patient that had been large, swollen, and painful at study initiation were no longer visible. No patient experienced disease progression or signs of visceral disease. The average percent decrease in lesion area for all target lesions was 20% (p < 0.01). A patient's response to therapy appeared to be independent of anti-HIV regimen, HIV viral load, or previous KS treatments. These results suggest that docosanol merits further investigation as a potential topical therapy in the treatment of AIDS-associated Kaposi's sarcoma lesions.

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.

Response to treatment of chronic hepatitis C with interferon alpha in patients infected with HIV-1 is associated with higher CD4+ cell count

The aim of this study was to assess the efficacy and tolerance of interferon alpha (IFN alpha) treatment of chronic hepatitis C in HIV-seropositive patients. Seventeen patients with actively replicating hepatitis C were consecutively enrolled and treated with IFN alpha 5 MIU three times a week and followed up for at least 6 months after cessation of treatment. Eight patients responded to IFN alpha therapy with a complete remission of signs of active hepatitis and viral replication (ALT, HCV-RNA) at the end of treatment with IFN alpha. A sustained complete remission (ALT, HCV-RNA) for at least 6 months after the end of treatment was achieved in five of these eight patients. Complete responders had higher CD4+ cell counts (median 525/microliter) compared to non-responders (median 245/microliter) (p < 0.001). All patients but one completed at least 4 months of treatment. No severe toxicity (> WHO grade 2) due to IFN alpha treatment occurred. The results indicate that IFN alpha treatment of chronic hepatitis C in HIV-seropositive patients is successful in a considerable number of cases. Success of treatment with IFN alpha is related to higher CD4+ cell counts.

Drug treatment of HIV-related opportunistic infections

The AIDS epidemic has led to the emergence of several disease entities which in the pre-AIDS era were rare or seemingly innocuous. Experience of treating these diseases varies. In some instances, such as Pneumocystis carinii pneumonia, there is an abundance of published literature to direct our course of action. However, for many of these newly recognised diseases our treatment experience is limited. Furthermore, in many instances, well controlled trials evaluating treatment modalities in the AIDS population are lacking. We have identified 13 disease entities (P. carinii pneumonia, toxoplasmosis, cryptococcosis, histoplasmosis, Mycobacterium tuberculosis, Mycobacterium avium complex, cytomegalovirus, coccidioidomycosis, isosporiasis, candidosis, Kaposi's sarcoma, herpes simplex virus, and varicella zoster virus) and have reviewed the current literature with regard to their treatment.

Kaposi's sarcoma and its management in AIDS patients. Recommendations from a Scandinavian Study Group

KS is the most frequent malignancy in homo/bisexual male AIDS patients, affecting more than 30% of these patients. KS may present itself as a few innocent cutaneous lesions or may show progression resulting in severe morbidity and mortality. Approximately half of the patients may develop severe progressive disease. The prognosis of patients with progressive disease is poor, with a median survival of less than 6 months. There is no cure for AIDS-related KS, but several therapies are available for palliation. The treatment options may be applied locally or systemically. Radiotherapy is efficacious and safe, but only a few lesions may be treated at one time. For severe progressive KS, systemic therapy with various forms of chemotherapy is used. Three regimes in particular have been focused on, namely bleomycin/vincristine (BV), doxorubicin + BV (DBV), or liposomal daunorubicin (LD) administered every 2 weeks. The agents result in a clinically relevant response (in 50-80% of patients) 2-4 weeks after initiation, but few patients have complete remission of the KS (< 10%), and the tumour may relapse after 4-6 months despite continued therapy. BV is less effective but also less toxic compared with the other regimens. Time to response for DBV may be slightly better than for LD, but the overall efficacy of these 2 regimes is similar. LD treatment is associated with significantly fewer episodes of peripheral neuropathy and alopecia than treatment with DBV. Thus, the recommended order of use of chemotherapeutic agents is BV, LD and DBV. Alpha-interferon may have a role in the small percentage of patients with CD4 cell count > 200 mill/L. In conclusion, several therapeutic options are available for palliation of KS. All systemically applied therapies are associated with severe side-effects and the optimal choice of treatment is a careful balance between response and toxicity. The recent discovery of human herpes virus 8 as a putative causative agent for KS and new potent groups of anti-retroviral agents, may lead to the development of more effective treatments of KS.

Overview of the management of AIDS-related Kaposi's sarcoma

OBJECTIVE

To review the epidemiology, pathogenesis, clinical presentation, diagnosis, and staging of Kaposi's sarcoma (KS), as well as the current role of local and systemic therapies in the management of AIDS-related KS (AIDS-KS).

DATA SOURCES AND STUDY SELECTION

MEDLINE and CANCERLIT searches of the English-language medical literature were conducted. Emphasis was placed on studies published since the onset of the AIDS epidemic in the early 1980s. A manual review of selected bibliographies was also completed.

DATA SYNTHESIS

AIDS-KS is a disease with a heterogeneous presentation that affects approximately 20% of patients with AIDS. Although the proportion of AIDS patients developing this disease during the course of their illness is declining, the actual number of AIDS-KS cases is increasing. The etiology of AIDS-KS is not clear, but a sexually transmitted cofactor has been implicated. Recent reports demonstrate that a herpes-like virus may be responsible for the development of KS in patients with and without AIDS. Furthermore, the cellular origin of KS has not been identified and questions remain about whether KS represents a true malignancy. The system used in staging patients with AIDS-KS has changed dramatically since initial therapeutic trials were conducted; this may account for observed differences in outcome among trials. The immunologic status of patients is now included as part of the staging system, since it has prognostic significance. Since specific therapy for AIDS-KS is not curative and does not prolong survival, it should be directed at improving patient cosmesis and palliation of disease-related symptoms. Local therapy, such as radiation, cryotherapy, and intralesional chemotherapy, is recommended for the management of limited disease. Systemic interferon alfa or chemotherapy is indicated for disseminated disease. Interferon alfa is useful in patients with predominantly mucocutaneous disease and is most effective in patients with good prognostic factors, such as absence of B symptoms, no history of opportunistic infections, and a CD4 count of more than 200 cells/mm3. Interferon alfa alone or in combination with zidovudine produces responses in approximately 30% of AIDS-KS patients with good prognostic factors. Single-agent or combination chemotherapy is indicated for rapidly progressive or advanced AIDS-KS. Commonly used agents include doxorubicin, daunorubicin, bleomycin, vincristine, and vinblastine. Responses can be expected in at least 50% of patients treated with single-agent or combination chemotherapy. However, many patients are unable to tolerate the toxicity associated with systemic AIDS-KS therapy. Future research will focus on therapies that target the underlying pathogenesis of this disease.

CONCLUSIONS

The optimal therapy for patients with AIDS-KS has not been determined. Treatment is appropriately directed at palliation of disease-related symptoms as no therapy has been unequivocally proven to impact survival. Local therapies should be used in the management of localized disease, while systemic therapy is appropriate for disseminated disease. Interferon alfa is useful in patients with primarily mucocutaneous disease or asymptomatic visceral involvement. Chemotherapy is indicated in patients who have rapidly progressive or advanced disease. Therapy must be individualized according to the patient's disease course and other patient-specific factors.

Phase II study of 5-fluoruracil leucovorin and azidothymidine in patients with metastatic colorectal cancer

The primary objective of this study was to determine the response rate of patients with metastatic colorectal cancer to combined therapy with 5-fluorouracil (5-FU), leucovorin, and intravenous azidothymidine (AZT), a thymidine nucleoside analog. By itself, AZT has limited antineoplastic efficacy. However, experimental studies indicate that 5-FU enhances the antitumor activity of AZT by inhibiting synthesis of normal thymidine nucleotides with which AZT competes for incorporation into nucleic acids. A phase I study defined the maximum tolerated dose of AZT as 7 g/m2 with hypotension during the infusion being the dose-limiting toxicity. A phase II study was performed with oral leucovorin (100 mg p.o. hourly for 4 h prior to 5-FU and 4 h and 8 h after 5-FU), bolus 5-FU (400 mg/m2) followed 1 h later by a 2-h infusion of AZT (7 g/m2). Treatment was given weekly for 4 weeks followed by a 1-week break, which constituted a cycle of therapy. Responses were evaluated after every two cycles. Patients continued on therapy as long as they tolerated treatment and did not have progressive disease. Of 15 evaluable patients who had received no chemotherapy there was 1 complete response and 4 partial responses (a 33% response rate), whereas only 1 of 6 patients who had received prior adjuvant chemotherapy had a partial response (17%). An additional 10 patients had stable disease lasting 2-14 months. Therapy was well tolerated with the only one instance each of grade 3 nausea and vomiting, diarrhea, anemia, and hypotension. Approximately 50% of treatments were accompanied by mild hypotension, which was easily corrected by increasing the rate of normal saline infusion. There was no difficulty administering this regimen in the outpatient setting. While the overall response rate (29%) is comparable to that seen with combinations of 5-FU and leucovorin alone, in most reported series a considerably higher dose of 5-FU was utilized than in this study. Since patients in the present study experienced relatively little 5-FU toxicity, increasing the dose of 5-FU in this regimen would appear to be feasible and might result in a higher response rate.

Kaposi's sarcoma: advances and perspectives

Kaposi's sarcoma (KS) is an unusual neoplasm that has proved to be an enigma in many ways since its original description by Kaposi in 1872. Its epidemiology has stimulated tremendous interest, amplified markedly in 1981 when it became known as an original defining part of the complex of immune disorders now known as AIDS. The cell of origin, etiology, and therapy for both AIDS-associated and AIDS-unassociated KS continue as matters of intense investigation. In fact, whether it is a reactive hyperplasia or a true malignancy is still a matter of debate, as is the concept of multicentricity versus metastases. Epidemiologic studies suggest that a separate agent apart from HIV-1 may cause KS. A newly postulated KS-associated herpes virus may be linked. The role of the HIV-1 tat gene product, basic fibroblast growth factor, scatter factor, oncostatin M, and other factors that regulate the growth of KS cells are discussed, as well as therapeutic options.

Immune-based therapies for treatment of HIV infection

OBJECTIVE

To review the in vitro, animal, and clinical data on immune-based therapies for treatment of HIV infection.

DATA SOURCES

An extensive MEDLINE search was performed for interleukins, interferons, immunotoxins, tumor necrosis factor (TNF)-directed agents, vaccines, and gene therapy.

STUDY SELECTION

In vitro experiments with immune-based agents in cell lines infected with HIV were included. In addition, all human studies and case reports that used these agents in patients infected with HIV were selected. Additional literature included abstracts from international meetings on HIV and AIDS.

DATA EXTRACTION

Data regarding activity, efficacy, and toxicity were extracted from in vitro and in vivo studies. When conflicting data were observed, both viewpoints were stated to give an unbiased analysis. Because HIV research involves multiple social, ethical, and scientific issues, perspectives on these problems were addressed, where appropriate.

DATA SYNTHESIS

Current antiretroviral therapy is limited to short-term responses and has minimal effect on overall survival. Because the human immune response to HIV infection is effective at keeping the virus suppressed for a number of years, a focus of HIV research has been to examine immune-based therapies for treatment of HIV infection that attempt to augment enhance, or boost the patient's immune system. Interleukins, interferons, immunotoxins, TNF-directed therapies, vaccines, and gene therapy have been studied in patients infected with HIV. Properties shared among these therapeutic modalities include adverse effect profiles, response rates dependent on baseline immunocompetence, the potential to activate viral replication, the need for supportive care, and sensitive laboratory tests required for monitoring.

CONCLUSIONS

Immune-based agents represent a new approach to the treatment of HIV infection. Whereas antiretrovirals only inhibit viral replication, these agents are designed to enhance the immune system of the patient. Future attempts to manage HIV infection may combine standard nucleoside analogs with immune-based therapies.

Zidovudine. An update of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy

Zidovudine remains the mainstay in the treatment of patients infected with human immunodeficiency virus (HIV). The drug delays disease progression to acquired immunodeficiency syndrome (AIDS) and to AIDS-related complex (ARC), reduces opportunistic infections, and increases survival in patients with advanced HIV infection. There is evidence to suggest that zidovudine also delays disease progression in patients with mild symptomatic disease. Although one study has shown zidovudine to have no significant beneficial effects on survival or disease progression in patients with asymptomatic HIV infection, several other studies have shown zidovudine to delay disease progression in this patient group. Results from related ongoing studies are awaited with interest. Zidovudine reduces the incidence of AIDS dementia complex (ADC) and appears to prolong survival in these patients, and improves other neurological complications of HIV infection. The drug also appears to enhance the efficacy of interferon-alpha in patients with Kaposi's sarcoma. Although zidovudine is widely used as postexposure prophylaxis following accidental exposure to HIV, its efficacy in preventing seroconversion is unclear. Whether zidovudine prevents vertical transmission also remains to be determined. The overall efficacy of zidovudine in the treatment of children with HIV infection appears similar to that in adults despite more rapid disease progression in younger patients. Zidovudine-resistant isolates can emerge as early as after 2 months' therapy, and primary infection with zidovudine-resistant strains has been documented. Both zidovudine resistance and the syncytium-inducing HIV phenotype appear to be associated with poor clinical outcome. However, zidovudine resistance may revert on drug withdrawal or switching to an alternative therapy. Zidovudine-associated haematotoxicity may be dose-limiting. Nonhaematological adverse events associated with zidovudine therapy are generally mild and usually resolve spontaneously. Dosages of approximately 500 to 600 mg/day appear to be at least as effective as dosages of 1200 to 1500 mg/day and are better tolerated in patients with less advanced disease. However, optimal dosage are unclear. Despite beneficial effects, zidovudine monotherapy is not curative. There is evidence to suggest that the concomitant administration of zidovudine with didanosine or zalcitabine is effective in patients with HIV disease progression despite receiving zidovudine monotherapy, and there is some evidence that concomitant zidovudine plus didanosine therapy is more effective than alternating monotherapy. However, results from studies of combination therapy in asymptomatic patients, and from comparative combination therapy studies are awaited. Cotherapy with agents that augment haematopoiesis allows the continuation of therapeutic zidovudine dosages.(ABSTRACT TRUNCATED AT 400 WORDS)