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Gel Cuts AIDS, Herpes Risk for Women
2010 Vienna XVIII International AIDS Conference; July 2010
“The study was randomized, double-blind and placebo-controlled—the gold standard for clinical research—and the results were statistically significant. "It's a really well-done study," said Bruce Walker, director of the Ragon Institute of MGH, MIT and Harvard dedicated to immunology and HIV vaccine research. The herpes virus, HSV2, renders women more susceptible to HIV, so blocking that virus could add to the gel's ability to prevent HIV. "This is a potential game changer," said Dr. Walker, who was briefed on the results but wasn't involved in the study. Still, because it is the first study to show the gel works, "I would like to see a confirmatory study," said one of the leaders of the trial, Salim Abdool Karim. The gel, which the researchers estimate could prevent half a million infections over the next 10 years in South Africa, contained the antiretroviral drug tenofovir, provided free by California-based Gilead Sciences Inc., which markets it in the U.S. as Viread. Administered as a pill in cocktails, the drug is widely used to treat people already infected with the AIDS virus.
Tenofovir didn't show any activity against the herpes virus, HSV2, in test tube studies conducted by the company, so it is a mystery why the gel protected women against that virus, said Gilead Foundation President and Chairman Howard Jaffe. Mr. Jaffe, the person Gilead referred questions to, said the company would support continuing research and any attempt to win regulatory approval. A Desperate Need Young women in many parts of Africa have extremely high HIV rates. Below, the prevalence of HIV in pregnant women in rural Vulindlela, South Africa, near Durban, between 2005 and 2008. The gel—applied on the skin and containing less drug than pills—may cause fewer side effects. The South African trial found only a slight increase of mild diarrhea in patients using the tenofovir gel compared with placebo, and no evidence of drug resistance. This gel is the first one armed with an antiretroviral drug to complete an efficacy study. There are caveats. Many women at risk for HIV become pregnant. There is no evidence the drug causes birth defects, but the researchers want it tested. There was a wide margin of error in the results, in part because the trial was only medium-sized. It followed 889 women at an urban and rural site for between one and two and a half years. Sixty out of the 444 women using the placebo gel contracted HIV, versus 38 among the 445 on the tenofovir gel, a benefit of 39%. With the margin of error, the gel could have reduced infection rates by as much as 60% or as little as 6%. Halting a Cellular Invasion At 12, 18, 24 and 30 months, the gel showed statistically significant protection against HIV, and women who used the gel consistently appeared better protected than those who used it off and on. While such consistent findings are impressive, the trial wasn't designed to have enough statistical power to win regulatory approval for the gel, said Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, who wasn't involved in the study. It is "a proof of concept that needs to be validated" by a second trial, he said. A larger trial of approximately 5,000 women, using the same gel but with a different dosing regimen, is being conducted in several African countries. Results aren't expected until 2013."
Jimbo’s Opinion
Viread (Tenofovir) is ineffective against HSV2 (genital herpes virus), but it provided 51% protection against genital herpes according to this study which was touted as a “breakthrough study,” for 39% chance of HIV protection to women; (protected 22 more women as compared to the placebo) in this meaningless small study in terms of studying a major public health problem. |