SAN FRANCISCO — The first randomized, controlled clinical study of an antiviral medication's effects on human herpesvirus 8 found a 79% reduction in viral shedding in the oropharynx of 26 men taking 900 mg/day of valganciclovir, Dr. Corey Casper reported.
Human herpesvirus 8 (HHV-8) causes Kaposi's sarcoma, multicentric Castleman disease, and primary effusion lymphoma. The virus must actively replicate to cause and maintain Kaposi's sarcoma and multicentric Castleman disease. The study's results suggest that valganciclovir may be an effective and safe way to both prevent and treat these HHV-8-related diseases, he said at the annual meeting of the Infectious Diseases Society of America.
Sixteen of the 26 participants had HIV infection. Subjects were randomized to 8 weeks of oral valganciclovir or placebo, followed by a 2-week washout period. Then participants took the alternative treatment for an additional 8 weeks.
All 26 subjects completed the study, and all but 1 adhered to the study regimen, according to pill counts. Participants collected oropharyngeal secretions daily at home.
While patients were taking valganciclovir, the median percentage of days with HHV-8 DNA detected decreased to 9%, compared with 43% on placebo—a 79% reduction, said Dr. Casper of the University of Washington, Seattle.
The effect was seen regardless of HIV status. The median shedding rate decreased from 63% to 23% in HIV-positive men and from 15% to 5% in HIV-negative men, a 64% drop in each subgroup. The greatest suppression in viral shedding was seen at 2 weeks, after which the effect remained stable until the drug was stopped. Shedding rates returned to baseline levels within 1 week of stopping valganciclovir.
The study was funded by Roche Laboratories Inc., which makes valganciclovir, and the National Institutes of Health.
Seven men on valganciclovir and four on placebo developed diarrhea—the only significant difference in side effects observed between the groups.
It's not yet known whether a different dose of valganciclovir, or another antiviral medication, might more effectively limit HHV-8 replication, he said.