Three clinical trials starting this year will test the effectiveness of Viread (tenofovir disoproxil fumarate) in preventing HIV. Viread, a nucleotide reverse transcriptase inhibitor, is currently approved to treat patients already infected with HIV. Clinical studies showed that Viread is relatively less toxic and less prone to the development of resistance towards it. Gilead Sciences, Foster City, CA makes and markets Viread since 2001 with estimated sales of $550 to $570 million in 2003.
Several years ago, a research team headed by Dr. Roberta Black at the University of Washington’s Regional Primate Research Center in Seattle, published a report in Science demonstrating Viread’s effectiveness in preventing simian immunodeficiency virus (SIV) infection in monkeys (Tsai CC et al., Science 270:1197-1199, Nov. 17, 1995). The effectiveness of Viread [then called (R)-9-(2-phosphonylmethoxypropyl)adenine (PMPA)] was tested both pre- and post-exposure in preventing SIV in macaques as a model for HIV prevention in humans. Viread was administered beginning 48 hours before, 4 hours after, or 24 hours after virus inoculation. The once daily treatment was continued for 4 weeks. Virologic, immunologic, and clinical parameters of the macaques were monitored for up to 56 weeks. Viread prevented SIV infection in all macaques without toxicity, whereas all control macaques became infected. The results indicated that Viread was able to prevent the SIV infections in monkeys and suggested that it may have similar effects on HIV in humans.
The Bill and Melinda Gates Foundation will pay $6.5 million to test Viread in 2,000 people in Cambodia, Ghana, and other countries. The U.S. National Institutes of Health has awarded a $2.1 million grant to the University of California to evaluate Viread in 960 Cambodian women including many at-risk prostitutes. The U.S. Centers for Disease Control is paying $3.5 million for testing in 400 uninfected gay and bisexual men.
HIV has so far infected about 40 million people worldwide and is spreading rampantly in parts of Africa and Asia. Because it does not have to be taken repeatedly, a vaccine would be a more effective means to slow the rate of transmission but development has proven elusive and no vaccine is predicted to be available for at least the next decade. At the present time, a drug may be the best means to slow the spread of HIV.
Several years ago, a research team headed by Dr. Roberta Black at the University of Washington’s Regional Primate Research Center in Seattle, published a report in Science demonstrating Viread’s effectiveness in preventing simian immunodeficiency virus (SIV) infection in monkeys (Tsai CC et al., Science 270:1197-1199, Nov. 17, 1995). The effectiveness of Viread [then called (R)-9-(2-phosphonylmethoxypropyl)adenine (PMPA)] was tested both pre- and post-exposure in preventing SIV in macaques as a model for HIV prevention in humans. Viread was administered beginning 48 hours before, 4 hours after, or 24 hours after virus inoculation. The once daily treatment was continued for 4 weeks. Virologic, immunologic, and clinical parameters of the macaques were monitored for up to 56 weeks. Viread prevented SIV infection in all macaques without toxicity, whereas all control macaques became infected. The results indicated that Viread was able to prevent the SIV infections in monkeys and suggested that it may have similar effects on HIV in humans.
The Bill and Melinda Gates Foundation will pay $6.5 million to test Viread in 2,000 people in Cambodia, Ghana, and other countries. The U.S. National Institutes of Health has awarded a $2.1 million grant to the University of California to evaluate Viread in 960 Cambodian women including many at-risk prostitutes. The U.S. Centers for Disease Control is paying $3.5 million for testing in 400 uninfected gay and bisexual men.
HIV has so far infected about 40 million people worldwide and is spreading rampantly in parts of Africa and Asia. Because it does not have to be taken repeatedly, a vaccine would be a more effective means to slow the rate of transmission but development has proven elusive and no vaccine is predicted to be available for at least the next decade. At the present time, a drug may be the best means to slow the spread of HIV.
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