Treating the AIDS-related cancer Kaposi's sarcoma (KS) became easier with the introduction of HAART. Indeed, sometimes KS lesions would simply fade in HAART users without the need to resort to chemotherapy. As HIV develops resistance to HAART, the immune system again becomes weak, allowing previously controlled problems to flare up. Doctors in Verona and Rome, Italy, recently reported details about two HIV positive men who developed new KS lesions despite long-term use of HAART.
In both cases the men had been taking two nucleoside analogues and the protease inhibitor saquinavir. (We don't know if they were using the older version of the drug, Invirase, or the new, more potent formulation, Fortovase.) When the KS lesions appeared, both men had CD4+ counts greater than 300 and viral load levels below 100 copies. Doctors gave them chemotherapy — vincristine, vinblastine and interferon-alpha — but this had no effect on the KS.
The doctors then prescribed the antiviral drug cidofovir (Vistide) 5mg/kg of body weight, given intravenously once weekly for the first two weeks and later once every two weeks. One of the men received the drug for 10 months and the other for 12 months. After three months of cidofovir, in both men the KS lesions began to fade and eventually disappeared. When the men stopped using cidofovir they remained free from KS for a further six months and 15 months respectively.
The reason cidofovir worked is that is has antiviral activity against many viruses, including the virus that can cause KS — human herpes virus-8 (HHV-8). Normally the immune system keeps this virus under control but HHV-8 levels rise as immunity weakens in people infected with this virus. For most of the time that the men received cidofovir, HHV-8 activity was suppressed. Unfortunately the drug is unable to cure this viral infection, so the lesions eventually returned. Perhaps if their anti-HIV regimen were changed, HHV-8 would again be brought under control. No side effects caused by cidofovir were reported.
In Canada, cidofovir is available to doctors who request the drug via Health Canada's Special Access program. In the U.S., the manufacturer, Gilead Sciences, supplies cidofovir. In many other countries cidofovir is distributed by the pharmaceutical company Pharmacia.
REFERENCES
1. Holkova B, Takeshita K, Cheng DM, et al. Effect of highly active antiretroviral therapy on survival in patients with AIDS-associated pulmonary Kaposi's sarcoma treated with chemotherapy. Journal of Clinical Oncology 2001;19(18):3848-3851.
2. Mazzi R, Parisi SG, Sarmati L, et al. Efficacy of cidofovir on human herpes virus 8 viraemia and Kaposi's sarcoma progression in two patients with AIDS. AIDS 2001;15(15):2061-2062.
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Copyright © 2001 - TreatmentUpdate. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Editor, The Canadian AIDS Treatment Information Exchange, 555 Richmond St. West, Suite 505, Box 1104, Toronto, ON, M5V 3B1 • Phone: 416-203-7122 • Toll Free: 1-800-263-1638 • Fax: 416-203-8284 http://www.catie.ca.
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